Intra-operative Hypertension as a Predictor of Surgical Outcomes in Microvascular Decompression Surgery for Trigeminal Neuralgia

Intra-operative Hypertension as a Predictor of Surgical Outcomes in Microvascular Decompression Surgery for Trigeminal Neuralgia | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Intra-operative Hypertension as a Predictor of Surgical Outcomes in Microvascular Decompression Surgery for Trigeminal Neuralgia Bhavika Gupta, Mohammadmahdi Sabahi, Romel Corecha Santos, Yatin Srinivash, and 4 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-3949568/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Objective: The trigeminocardiac reflex (TCR) has traditionally been characterized by a sudden decrease in heart rate, asystole, or hypotension during the manipulation of the trigeminal nerve (MTN) or its branches. While this classical TCR is well-documented, there is limited literature on alternative forms of TCR, such as the development of intraoperative hypertension (HTN) or tachycardia, and the underlying pathogenesis. Furthermore, a gap exists in understanding the correlation between intraoperative blood pressure readings and postoperative outcomes, particularly regarding pain relief in patients with trigeminal neuralgia (TN). Our study aims to examine intraoperative blood pressure trends during microvascular decompression (MVD) for TN and assess their impact on postoperative outcomes. Methods: We selected 90 patients who underwent MVD for TN treatment. Blood pressure and heart rate were recorded both preoperatively and during the procedure, specifically during the MTN period, using an arterial line. The Barrow Neurological Institute (BNI) Pain Scale was calculated for all patients both pre- and post-operatively to evaluate pain relief after surgery. Results: The mean age of the patients was 61.0±12.35 years, with 64.4% being females. Classical TCR (hypotension) was observed in only 2.2% of patients, whereas 80% of patients developed hypertension (≥140/90) during MTN. The mean preoperative systolic blood pressure was 128 ± 22.25, and the mean intraoperative systolic blood pressure during MTN was 153.1± 20.2. An analysis of covariance, utilizing either preoperative BNI or duration of symptoms as covariate variables, revealed a statistically significant association between intraoperative HTN and postoperative BNI. A linear regression model demonstrated that intraoperative HTN following MTN significantly predicted a lower postoperative BNI score (p=0.006). Conclusions: Intraoperative HTN during MTN, an observed yet underexplored phenomenon, demonstrated a correlation with improved postoperative outcomes. Furthermore, it is recommended to conduct additional investigations into potential neurovascular conflicts in patients not manifesting intraoperative HTN following MTN. A comprehensive understanding of TCR, encompassing its various forms, is vital for optimizing surgical management. This study underscores the imperative for further research to unravel the mechanisms linking intraoperative HTN to surgical outcomes in TN patients. Trigeminal nerve Hypertension Trigeminocardiac reflex microvascular decompression pain Figures Figure 1 Figure 2 Figure 3 1. Introduction Trigeminal Neuralgia (TN) is a facial pain disorder and is characterized by sudden, severe episodes of facial pain that typically last for a few seconds. The pain is usually triggered by normal activities like speaking or eating [ 1 ]. The most common etiology for TN is believed to be related to compression or irritation of the trigeminal nerve by the surrounding vasculature [ 2 ]. Microvascular Decompression (MVD) is the most common treatment for medically refractory TN. The Trigeminal Cardiac Reflex (TCR) is a complex reflex involving the trigeminal nerve and the autonomic nervous system and is often triggered by stimulation of the trigeminal nerve, which sends signals to the brainstem and the cardiovascular centers, resulting in changes in heart rate and blood pressure [ 3 ]. When the trigeminal nerve is activated, it sends a signal to the brain which can result in several different outcomes. Sensory stimulation of the nerve is done via the Gasserian ganglion, which activates the cardioinhibitory parasympathetic vagal neurons. The sensory nucleus of the trigeminal neve is connected to the reticular formation via polysynaptic connections mediated endogenously by cholinergic and serotonin receptors [ 4 ]. Furthermore, the central circuit reflex lies within the brainstem which further mediates cardiac responses. While these underlying pathways describe the pathogenesis of TCR, the clinical manifestation, from mild reflexive response to severe life-threatening bradycardia, varies significantly. There are several forms of TCR, including excitatory and inhibitory reflexes. Classical TCR is defined as hypotension, bradycardia, and loss of consciousness, during manipulation of the trigeminal nerve (MTN) or its branches and is observed in up to 18% of MVDs performed for TN [ 5 ]. The TCR can also be modulated by other reflexes, such as the baroreceptor reflex [ 6 ]. Additionally, the TCR can be influenced by various factors, such as age, stress, and underlying disease. Understanding the role of the TCR is important for the management of various cardiovascular risk factors such as perioperative myocardial infarction and acute kidney injury during microvascular decompression [ 7 ]. While TCR is a protective physiological reflex, the exaggeration of responses can be deemed pathological. Understanding the mechanisms behind TCR, and the different outcomes it can cause is essential for the effective management of patients with certain medical conditions, such as trigeminal neuralgia. The appearance of TCR is widely reported in the literature [ 5 , 6 , 8 ], there are no reports on the different patterns of TCR observed during microvascular decompression surgery. Additionally, there is a paucity of literature on how developing TCR during surgery correlates with outcomes. To our knowledge, this is the first study of its kind to report on the surgical outcomes and post-surgical effects of developing intraoperative hypertension (HTN) during microvascular decompression surgery. 2. Material and Methods 2.1. Data collection We conducted a retrospective study with 90 patients who underwent MVD for medically refractory TN at our center from January 2013 to January 2023. Patient demographics such as age, sex, prior history of HTN, comorbidities, medications, involved trigeminal nerve branches, pre-operative vital signs, and intra-operative vital signs were collected via manual chart review. Changes in blood pressure and heart rate were recorded pre-operatively and during the procedure, specifically at the time of MTN. Both an arterial line, as well as a non-invasive blood pressure cuff, were used. This data was collected by reviewing the anesthesiologist’s intra-operative report. Additionally, the occurrence of TCR, if any, was recorded by the anesthesiologist at the time of the MTN. Additionally, the pre-and post-operative Barrow Neurological Index (BNI) pain scores for trigeminal neuralgia were calculated for all patients and used as the primary outcome measure for post-operative symptom relief. 2.2. Statistical analysis SPSS 29.0 statistical software (IBM Corp., Armonk, NY) was used for data analysis. Means and standard deviation were computed between the two groups with a Mann Whitney test for nonparametric continuous data, and with Chi square or Fisher exact test when appropriate for categorical data. Analysis of covariance (ANCOVA) and linear regression were performed. We checked the assumptions of ANCOVA, including homogeneity of regression (HOR) slopes, homogeneity of variances, and normality of residuals. None of the assumptions were violated. A p-value of 0.05 or less was defined as statistically significant. 3. Results 3.1 Patient characteristics Our study included a total of 90 patients. Table 1 shows the demographic and clinical data of the patients. The mean age of the population was 61.0±12.35 years and included 32 (35.6%) males and 58 (64.4%) females. 35 patients (38%) had a prior history of HTN, and 25 patients (28%) had high blood pressure just prior to surgery. As documented by the anesthesiologist, only 2 (2.2%) patients developed the classical TCR (hypotension) whereas 88 (80%) patients experienced the hypertensive variant of TCR (BP>140/90) during MTN. The mean pre-operative systolic BP was 128±22.24 mmHg, and the mean intraoperative systolic BP was 153.1±20.2 mmHg. Mean arterial pressure, systolic and diastolic BP following MTN in both groups has been demonstrated in Figure 1 . Minimum and maximum intra-operative pulse recordings were 60±12.27 beat per minute (BPM) and 78.15±12.67 BPM, respectively. Changes in BP from pre-operative assessment to intra-operative assessment during MTN have been illustrated in Figure 2 for both groups. 3.2 Outcome Evaluation The distribution of systolic blood pressure in both groups, categorized according to post-operative BNI, is depicted in Figure 3 . The main aim of the analysis was to study the relationship between developing intra-operative HTN and post-operative BNI score, while controlling for the pre-operative BNI score and duration of symptoms. Some other factors that are thought to affect outcomes of MVD such as laterality of symptoms, branches of trigeminal nerve involved, etiology of nerve compression and duration of symptoms prior to surgery were also analyzed [9-11]. Additional univariate analyses of covariance were performed to study the effect of demographic variables such as age, sex, history of HTN, history of diabetes, smoking status, and obesity on post operative BNI scores. For the analysis, patients were divided into two groups. The first group did not develop intra-operative HTN during MTN, while the second group developed sustained HTN during MTN for few minutes. Initially, we performed a univariate ANCOVA between intraoperative HTN and pre-operative BNI. The results showed no significant difference between the two groups regarding the BNI, thus allowing us to choose the pre-operative BNI as a covariate. Next, we performed HOR, which did not show any significant relationship either. After satisfying both these prerequisites an analysis of covariance performed. This process was repeated for duration of symptoms as the covariate, with post-operative BNI as the outcome. In the first model with preoperative BNI as the covariate variable there was a statistically significant (p=0.021) association between intraoperative HTN and postoperative BNI. A linear regression model for the same showed that patients who experienced intra-operative HTN have a 0.5-point decrease in post operative BNI as compared to patients who do not have intra-operative HTN, thus predicting that intraoperative HTN is associated with a lower postoperative BNI score. The second model with duration of symptoms as the covariate, also showed a significant association (p=0.007) between intra-operative HTN and post-operative BNI. Similarly, linear regression showed that patients who experienced intra-operative HTN have a 0.6-point decrease in post operative BNI as compared to patients who do not have intra-operative HTN, thus predicting that intraoperative HTN is associated with a lower postoperative BNI score, when controlling for duration of symptoms. Additional univariate analyses demonstrated a significant relationship between past medical history of HTN and post operative BNI (p=0.040), while controlling for pre-operative BNI. Further analyses of covariance with pre-operative BNI and duration of symptoms as covariates did not show any significant relationship between age, sex, pre-operative HTN, past medical history of diabetes, obesity, smoking status, laterality of symptoms, branches involved, etiology of compression and duration of symptoms with the post-operative BNI ( Table 2 ). 4. Discussion In our study of 90 patients, 72 (80%) developed episodes of HTN upon MTN during MVD. These patients had statistically significantly lower post-operative Barrow Neurological Index (BNI) scores and theoretically better outcomes post decompression, even after controlling for pre-operative BNI and duration of symptoms. Additionally, patients with a past medical history of HTN also had lower post-operative BNI scores when compared to patients who did not. The mean post-operative BNI scores was 1.46 for the group that developed intra-operative HTN as opposed to 2 for the group that did not develop HTN during the surgery (p = 0.006). The classical TCR in humans was first described by Schaller et al. in 1999 during cerebellopontine angle surgery [ 8 ]. Since then, he has defined TCR as a drop in mean arterial blood pressure by more than 20% upon stimulation of the trigeminal nerve complex. 12 To understand the different ways in which the TCR may present, it is important to understand the anatomy and the different trigger points available for the activation of the reflex. Schaller and his colleagues have further subdivided this reflex into three categories, depending on the anatomical location. The reflex includes the Central, Peripheral, and Ganglion subtype [ 8 ]. The afferent limb of the TCR is made up by the sensory nerve fibers traveling to the Gasserian ganglion located in the 4th ventricle. However, the afferent limb changes depending on the subtype of TCR (central, peripheral, or ganglion) [ 6 , 8 , 12 ]. The efferent limb is made up by the motor nuclei of the Vagus nerve and its parasympathetic nerve fibers. Naturally, the most common effect of activating this response would be a decrease in blood pressure or heart rate, as is seen in classical TCR [ 8 , 12 , 13 ]. Review of the literature demonstrates the effects of TCR on both the parasympathetic (PNS) and sympathetic nervous system (SNS). Chen et al. showed that pre-treating with labetalol or anti-cholinergic agents prevented bradycardia and hypertension during balloon compression rhizotomy (BCR) [ 14 ]. Studies in animal models show that MTN can also lead to an increase in adrenaline release, thus activating the SNS. Additionally, HTN during MTN has also been described in radiofrequency thermocoagulation (RFT). Foramen ovale puncture led to an increase in BP and heart rate (HR) in all the patients in a study done by Meng et al. Thermal energy was considerably stronger than electrical energy for causing increases in BP and HR and was found to be directly proportional to the amount of current that is directed at the lesioned site [ 15 ]. As the frequency of the thermal current increased, the depressor response converted to a stressor response. Additionally, the electrical stimulation and heating during RFT also heated up the C fibers leading to rises in the BP and pulse [ 15 ]. Additionally, if a patient has lighter anesthesia, the pain of the operation can lead to a severe sympathetic nervous response. Direct stimulation of the trigeminal ganglion may lead to a vasoconstrictive response, thus leading to HTN [ 16 ]. As shown by Schaller et al. the TCR has three components and, depending on the component stimulated, may have a different physiologic response [ 13 ]. Studies have demonstrated that the peripheral variant of the TCR has bradycardia, HTN and bouts of apnea. Whereas a more central manipulation leads to hypotension. Thus, depending on the area and degree of compression, MVD for TN may produce a different type of TCR [ 4 , 8 , 12 , 13 , 17 ]. Most MVD procedures involve MTN near the Gasserian ganglion around Meckel’s cave. This ganglion is surrounded by sympathetic and parasympathetic nerve fibers originating from the carotid plexus. This anatomic relationship may explain the variations in the TCR [ 18 ]. While developing the hypertensive variant of the TCR during MVD is not well studied, it is commonly observed and well-reported during other procedures involving MTN. Additionally, the balance of which the autonomic nervous system gets activated could vary from patient to patient making the response variable and unreliable. A study performed by Liu et al. showed that more than 80% of patients experienced hypertension, during trigeminal nerve combing [ 19 ]. Additionally, these patients had an increase in the level of epinephrine, inferring that the increase in BP was directly related to the activation of the sympathetic nervous system. The authors concluded that the increased HTN was a result of vasoconstriction secondary to the sympathetic nervous system. Most interestingly, Patients who did not develop HTN during combing did not benefit from the procedure. They hypothesized, that the TN in these patients was likely due to a central complex, rather than peripheral compression syndrome. Further support for this theory was strengthened by the underlying diagnosis of multiple sclerosis (MS) in these sub-set of patients. Thus, these patients would not have benefited from the MVD. The major takeaway from their study was that it is important to consider this factor and be prepared for this occurrence, as such high increases in blood pressure can lead to severe intraoperative morbidity. Finally, one must be careful to avoid intracerebral hemorrhage, during MVD with such high blood pressures [ 19 ]. Like our results of improved outcomes in patients with blood pressure spikes, Zuo et al. reported that developing intra-operative HTN during BCR meant that the compression was successful, and further supported the use of continuous intra-operative blood pressure monitoring [ 20 ]. While most surgeons believe that it is best to prevent TCR rather than treat it intra-operatively, due to its various forms, pre-treatment with atropine is not recommended. However, there are limiting certain risk factors that can decrease the incidence of TCR. The best strategy is to prevent these risk factors and thus prevent the TCR from occurring. 6 In addition, the anesthesiology team should be alerted when the neurosurgeon is MTN and the neurosurgeon must always use gentle retraction while doing so. Finally, acknowledging the prognostic significance of intraoperative HTN subsequent to MTN, it is recommended to explore alternative neurovascular conflicts in patients who do not manifest this response. This ensures a thorough investigation, confirming that the surgeon has considered all potential sites for decompression in the treatment of trigeminal nerve. Limitations The major limitation of this study is the small sample size and retrospective nature of this study. While our results were statistically significant, to deme their clinical significance and influence on surgical decision-making, a larger sample size and prospective studies must be conducted to determine the true effect of developing intra-operative HTN on outcomes of the procedure. 5. Conclusion As previously believed, the TCR exists in many forms. It is important to know the different anatomical locations of the trigeminal complex to understand what variant of the reflex will be evoked during surgery. The development of intra-operative HTN during MTN, regardless of either pre-operative BNI pain scale or duration of symptoms, may lead to better post-operative BNI scores and outcomes. As a result, the occurrence of intraoperative HTN subsequent to MTN may function as a prognostic indicator for surgical outcomes in patients with TN. Furthermore, it is recommended to conduct additional investigations into potential neurovascular conflicts in patients not manifesting intraoperative HTN following MTN. Further research is warranted to investigate the mechanisms underlying this association. Declarations Funding: None Conflicts of interest/Competing interests: All authors certify that they have no affiliations with or involvement in any organization or entity with any financial interest (such as honoraria; educational grants; participation in speakers' bureaus; membership, employment, consultancies, stock ownership, or other equity interest; and expert testimony or patent-licensing arrangements), or non-financial interest (such as personal or professional relationships, affiliations, knowledge or beliefs) in the subject matter or materials discussed in this manuscript. Ethics approval: All procedures performed in this study involving human participants were in accordance with the ethical standards and the 1964 Helsinki Declaration and its later amendments or comparable ethical standards and approved by the Institutional Review Board of Cleveland Clinic (IRB number: 23-327, 329/2023). Informed consent: Informed consent was obtained from all individual participants included in the study. Consent to participate: Informed consent to participate in this study was obtained from participants included in the study. Availability of data and material: The authors confirm that the data supporting the findings of this study are available within the article. References Green, A., et al., Post-herpetic trigeminal neuralgia treated with deep brain stimulation. Journal of clinical neuroscience, 2003. 10 (4): p. 512-514. Esmaeilzadeh, M., et al., When the nerve keeps firing: an institutional experience and systematic review on delayed response after microvascular decompression for trigeminal neuralgia. Neurological Sciences, 2023: p. 1-10. Chowdhury, T., R.B. Cappellani, and B. Schaller, Chronic trigemino-cardiac reflex in patient with orbital floor fracture: role of surgery and first description. Journal of Neurosurgical Anesthesiology, 2014. 26 (1): p. 91-92. Gorini, C., et al., Endogenous inhibition of the trigeminally evoked neurotransmission to cardiac vagal neurons by muscarinic acetylcholine receptors. Journal of neurophysiology, 2010. 104 (4): p. 1841-1848. Shibao, S., et al., The trigeminocardiac reflex during the anterior transpetrosal approach. World neurosurgery, 2017. 106 : p. 939-944. Meuwly, C., et al., Trigeminal cardiac reflex: new thinking model about the definition based on a literature review. Medicine, 2015. 94 (5). Kouz, K., et al., Intraoperative hypotension: Pathophysiology, clinical relevance, and therapeutic approaches. Indian journal of anaesthesia, 2020. 64 (2): p. 90. Schaller, B., Trigemino-cardiac reflex during microvascular trigeminal decompression in cases of trigeminal neuralgia. Journal of neurosurgical anesthesiology, 2005. 17 (1): p. 45-48. Cheng, J., et al., Nerve atrophy in trigeminal neuralgia due to neurovascular compression and its association with surgical outcomes after microvascular decompression. Acta Neurochirurgica, 2017. 159 : p. 1699-1705. Loayza, R., et al., Outcome after microvascular decompression for trigeminal neuralgia in a single center—relation to sex and severity of neurovascular conflict. Acta Neurochirurgica, 2023: p. 1-8. Duan, Y., et al., Degree of distal trigeminal nerve atrophy predicts outcome after microvascular decompression for Type 1a trigeminal neuralgia. Journal of neurosurgery, 2015. 123 (6): p. 1512-1518. Meuwly, C., et al., Definition and diagnosis of the trigeminocardiac reflex: a grounded theory approach for an update. Frontiers in neurology, 2017. 8 : p. 533. Schaller, B., Trigeminocardiac reflex: a clinical phenomenon or a new physiological entity? Journal of neurology, 2004. 251 : p. 658-665. Chen, C.-Y., et al., Comparison of the effects of atropine and labetalol on trigeminocardiac reflex-induced hemodynamic alterations during percutaneous microballoon compression of the trigeminal ganglion. Acta Anaesthesiologica Taiwanica, 2012. 50 (4): p. 153-158. Meng, Q., et al., Cardiovascular responses during percutaneous radiofrequency thermocoagulation therapy in primary trigeminal neuralgia. Journal of Neurosurgical Anesthesiology, 2008. 20 (2): p. 131-135. Kehler, C.H., et al., Blood pressure response during percutaneous rhizotomy for trigeminal neuralgia. Neurosurgery, 1982. 10 (2): p. 200-202. McCulloch, P.F., K.M. Faber, and W.M. Panneton, Electrical stimulation of the anterior ethmoidal nerve produces the diving response. Brain research, 1999. 830 (1): p. 24-31. Borghei-Razavi, H., et al., Unusual Appearance of Trigemino-Cardiac Reflex During Cerebellopontine Angle Surgery. World Neurosurgery, 2018. 112 : p. 298-299. Liu, J., et al., Relationship between arterial blood pressure during trigeminal nerve combing and surgical outcome in patients with trigeminal neuralgia. World Neurosurgery, 2020. 137 : p. e98-e105. Zuo, Y., et al., Continuous Intra-Arterial Blood Pressure Monitoring Improves the Efficiency of Percutaneous Balloon Compression of the Trigeminal Ganglion for Trigeminal Neuralgia. Pain Research and Management, 2022. 2022 . Tables Table 1: Comparison of demographic and clinical features between the two groups in the study population Intra-operative HTN (n=72) No Intra-operative HTN (n=18) p-value Sex Male Female 24 (33.3%) 48 (66.7%) 8 (8.6%) 10 (10.8%) 0.378 Age # 65 years (26-83 years) 60 years (34-74 years) 0.073 PMH of HTN 30 (41.7%) 5 (5.4%) 0.280 PMH of DM 9 (23.6%) 1 (1.1%) 0.680 Obesity 17 (23.6%) 7 (7.5%) 0.235 Smoking 33 (45.8%) 9 (9.7%) 0.751 Type of Compression Arterial Venous Mixed Nerve 49 (68.1%) 14 (19.4%) 5 (6.9%) 4 (5.6%) 11 (7.5%) 3 (3.2%) 4 (4.3%) 0 0.210 Symptom Laterality Right Left 38 (52.8%) 33 (45.8%) 11 (11.8%) 7 (7.5%) 0.745 Branch V1 V2 V3 Mixed 1 (1.4%) 24 (33.3%) 20 (27.8%) 27 (37.5) 1 (1.1%) 2 (2.2%) 3 (6%) 9 (9.7%) 0.231 Pre-operative HTN 21 (29.2%) 4 (4.3%) 0.556 Pre-operative BNI # 5 (3-5) 4 (3-5) 0.128 Post-operative BNI # 1 (1-4) 2 (1-4) 0.006 Length of symptoms # 36 days (1-360 days) 36 days (2-240 days) 0.266 # Continuous data is presented as median (Range) Abbreviations. BNI: Barrow Neurological Institute Pain Scale, HTN: Hypertension, PMH: Past medical history, DM: Diabetes Mellitus Boldface type indicates statistical significance (p < 0.05). Table 2 : Relationship between patient factors and post-operative BNI Fixed Factor p-value *Pre-operative BNI *Duration of symptoms Intra-operative HTN 0.021 0.007 Sex 0.815 0.695 PMH of HTN 0.040 0.066 Immediate pre-operative HTN 0.865 0.862 Laterality 0.528 0.581 Branch 0.821 0.768 PMH of DM 0.275 0.361 Obesity 0.622 0.568 Smoking 0.685 0.472 Type of compression 0.507 0.518 Age 0.332 0.368 Duration of symptoms 0.252 - *Covariates in each individual univariate model. Abbreviations. BNI: Barrow Neurological Institute Pain Scale, HTN: Hypertension, PMH: Past medical history, DM: Diabetes Mellitus Boldface type indicates statistical significance (p < 0.05). Additional Declarations No competing interests reported. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-3949568","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":273596293,"identity":"a88ec154-a87a-48ab-984b-bca5720c61d1","order_by":0,"name":"Bhavika Gupta","email":"","orcid":"","institution":"Allegheny General Hospital","correspondingAuthor":false,"prefix":"","firstName":"Bhavika","middleName":"","lastName":"Gupta","suffix":""},{"id":273596294,"identity":"88540013-2c9f-4e36-8e65-889c8e39cf8d","order_by":1,"name":"Mohammadmahdi Sabahi","email":"","orcid":"","institution":"Cleveland Clinic Florida","correspondingAuthor":false,"prefix":"","firstName":"Mohammadmahdi","middleName":"","lastName":"Sabahi","suffix":""},{"id":273596295,"identity":"a950cbcd-fbd0-4893-bb02-c55675dca3e1","order_by":2,"name":"Romel Corecha Santos","email":"","orcid":"","institution":"Cleveland Clinic Florida","correspondingAuthor":false,"prefix":"","firstName":"Romel","middleName":"Corecha","lastName":"Santos","suffix":""},{"id":273596296,"identity":"224ecd53-cd1c-48cb-a95d-c48910b8ef65","order_by":3,"name":"Yatin Srinivash","email":"","orcid":"","institution":"Dr. Kiran C. Patel College of Osteopathic Medicine, Nova Southeastern University, Fort Lauderdale, FL, USA.","correspondingAuthor":false,"prefix":"","firstName":"Yatin","middleName":"","lastName":"Srinivash","suffix":""},{"id":273596297,"identity":"73d85d62-9d9c-4cb2-b299-0bb8dee89c29","order_by":4,"name":"Raphael Augusto Correa Bastianon Santiago","email":"","orcid":"","institution":"Cleveland Clinic Florida","correspondingAuthor":false,"prefix":"","firstName":"Raphael","middleName":"Augusto Correa Bastianon","lastName":"Santiago","suffix":""},{"id":273596298,"identity":"2f131255-edf1-4e2e-af55-a81fc067ebca","order_by":5,"name":"Rocco Dabecco","email":"","orcid":"","institution":"Allegheny General Hospital","correspondingAuthor":false,"prefix":"","firstName":"Rocco","middleName":"","lastName":"Dabecco","suffix":""},{"id":273596299,"identity":"272595a4-df94-4b54-9aac-4c01a72d7a73","order_by":6,"name":"Badih Adada","email":"","orcid":"","institution":"Cleveland Clinic Florida","correspondingAuthor":false,"prefix":"","firstName":"Badih","middleName":"","lastName":"Adada","suffix":""},{"id":273596300,"identity":"6af66508-90ec-449c-8dea-532fd73a4d49","order_by":7,"name":"Hamid Borghei-Razavi","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAx0lEQVRIiWNgGAWjYBACAyBmZmA4IMcPZHwgSYuxZAMD4wyStCRuOECsFnP23sevCyruMG4+fvhhA0PFPbsGQlose46bWc8484zZ7EyaYQPDmeJkgloMbqSxGfO2HWYzu8HD/oCxLSGZoMMgWv4d5jGewcPYQKwW5se8DYclDCQgWuwIarHsOcbGzHPssIEEyC8JZxISCGoxZ29j/sxTc7i+vx0YYh8qEuwJagECNgk4E2hFYgMRWphR0glRtoyCUTAKRsHIAgCqkD8YF1TFAAAAAABJRU5ErkJggg==","orcid":"","institution":"Cleveland Clinic Florida","correspondingAuthor":true,"prefix":"","firstName":"Hamid","middleName":"","lastName":"Borghei-Razavi","suffix":""}],"badges":[],"createdAt":"2024-02-11 22:44:50","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-3949568/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-3949568/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":51443218,"identity":"305328d9-d471-40cd-8aa8-14e9fcbb8208","added_by":"auto","created_at":"2024-02-21 17:59:29","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":141838,"visible":true,"origin":"","legend":"\u003cp\u003eMean arterial pressure (MAP), systolic, and diastolic blood pressure following manipulation of trigeminal nerve (MTN) in both groups. HTN: hypertension\u003c/p\u003e","description":"","filename":"Figure1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-3949568/v1/d7c2f56f3cf4220f8972cc05.jpg"},{"id":51443249,"identity":"7c78ceae-fbc6-4907-8246-5cb8e1ef3aad","added_by":"auto","created_at":"2024-02-21 17:59:31","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":65390,"visible":true,"origin":"","legend":"\u003cp\u003eBlood pressure variations from pre-operative to intra-operative assessment during manipulation of trigeminal nerve (MTN) for both study groups. HTN: hypertension, BP: blood pressure\u003c/p\u003e","description":"","filename":"Figure2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-3949568/v1/6b1a467149c21b847e0b1b20.jpg"},{"id":51444653,"identity":"6aabe0f8-713f-445f-9974-f9da87864230","added_by":"auto","created_at":"2024-02-21 18:07:29","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":226482,"visible":true,"origin":"","legend":"\u003cp\u003eDistribution of systolic blood pressure in both groups, categorized according to post-operative Barrow Neurological Institute (BNI) pain scores. HTN: hypertension, BP: blood pressure\u003c/p\u003e","description":"","filename":"Figure3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-3949568/v1/a7475884e4cf4da3cccab240.jpg"},{"id":52045515,"identity":"9f322b94-cd7c-4757-946b-339393838e43","added_by":"auto","created_at":"2024-03-05 19:40:47","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":447770,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-3949568/v1/fb697365-12ef-4f54-a057-172fc97daf6f.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Intra-operative Hypertension as a Predictor of Surgical Outcomes in Microvascular Decompression Surgery for Trigeminal Neuralgia","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eTrigeminal Neuralgia (TN) is a facial pain disorder and is characterized by sudden, severe episodes of facial pain that typically last for a few seconds. The pain is usually triggered by normal activities like speaking or eating [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. The most common etiology for TN is believed to be related to compression or irritation of the trigeminal nerve by the surrounding vasculature [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. Microvascular Decompression (MVD) is the most common treatment for medically refractory TN. The Trigeminal Cardiac Reflex (TCR) is a complex reflex involving the trigeminal nerve and the autonomic nervous system and is often triggered by stimulation of the trigeminal nerve, which sends signals to the brainstem and the cardiovascular centers, resulting in changes in heart rate and blood pressure [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. When the trigeminal nerve is activated, it sends a signal to the brain which can result in several different outcomes. Sensory stimulation of the nerve is done via the Gasserian ganglion, which activates the cardioinhibitory parasympathetic vagal neurons. The sensory nucleus of the trigeminal neve is connected to the reticular formation via polysynaptic connections mediated endogenously by cholinergic and serotonin receptors [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Furthermore, the central circuit reflex lies within the brainstem which further mediates cardiac responses. While these underlying pathways describe the pathogenesis of TCR, the clinical manifestation, from mild reflexive response to severe life-threatening bradycardia, varies significantly. There are several forms of TCR, including excitatory and inhibitory reflexes. Classical TCR is defined as hypotension, bradycardia, and loss of consciousness, during manipulation of the trigeminal nerve (MTN) or its branches and is observed in up to 18% of MVDs performed for TN [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. The TCR can also be modulated by other reflexes, such as the baroreceptor reflex [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Additionally, the TCR can be influenced by various factors, such as age, stress, and underlying disease. Understanding the role of the TCR is important for the management of various cardiovascular risk factors such as perioperative myocardial infarction and acute kidney injury during microvascular decompression [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. While TCR is a protective physiological reflex, the exaggeration of responses can be deemed pathological. Understanding the mechanisms behind TCR, and the different outcomes it can cause is essential for the effective management of patients with certain medical conditions, such as trigeminal neuralgia. The appearance of TCR is widely reported in the literature [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e], there are no reports on the different patterns of TCR observed during microvascular decompression surgery. Additionally, there is a paucity of literature on how developing TCR during surgery correlates with outcomes. To our knowledge, this is the first study of its kind to report on the surgical outcomes and post-surgical effects of developing intraoperative hypertension (HTN) during microvascular decompression surgery.\u003c/p\u003e"},{"header":"2. Material and Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1. Data collection\u003c/h2\u003e \u003cp\u003eWe conducted a retrospective study with 90 patients who underwent MVD for medically refractory TN at our center from January 2013 to January 2023. Patient demographics such as age, sex, prior history of HTN, comorbidities, medications, involved trigeminal nerve branches, pre-operative vital signs, and intra-operative vital signs were collected via manual chart review. Changes in blood pressure and heart rate were recorded pre-operatively and during the procedure, specifically at the time of MTN. Both an arterial line, as well as a non-invasive blood pressure cuff, were used. This data was collected by reviewing the anesthesiologist\u0026rsquo;s intra-operative report. Additionally, the occurrence of TCR, if any, was recorded by the anesthesiologist at the time of the MTN. Additionally, the pre-and post-operative Barrow Neurological Index (BNI) pain scores for trigeminal neuralgia were calculated for all patients and used as the primary outcome measure for post-operative symptom relief.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2. Statistical analysis\u003c/h2\u003e \u003cp\u003eSPSS 29.0 statistical software (IBM Corp., Armonk, NY) was used for data analysis. Means and standard deviation were computed between the two groups with a Mann Whitney test for nonparametric continuous data, and with Chi square or Fisher exact test when appropriate for categorical data. Analysis of covariance (ANCOVA) and linear regression were performed. We checked the assumptions of ANCOVA, including homogeneity of regression (HOR) slopes, homogeneity of variances, and normality of residuals. None of the assumptions were violated. A p-value of 0.05 or less was defined as statistically significant.\u003c/p\u003e \u003c/div\u003e"},{"header":"3. Results","content":"\u003cp\u003e\u003cstrong\u003e3.1 Patient characteristics\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eOur study included a total of 90 patients. \u003cstrong\u003eTable 1\u003c/strong\u003e shows the demographic and clinical data of the patients. The mean age of the population was 61.0\u0026plusmn;12.35 years and included 32 (35.6%) males and 58 (64.4%) females. 35 patients (38%) had a prior history of HTN, and 25 patients (28%) had high blood pressure just prior to surgery. As documented by the anesthesiologist, only 2 (2.2%) patients developed the classical TCR (hypotension) whereas 88 (80%) patients experienced the hypertensive variant of TCR (BP\u0026gt;140/90) during MTN.\u003c/p\u003e\n\u003cp\u003eThe mean pre-operative systolic BP was 128\u0026plusmn;22.24 mmHg, and the mean intraoperative systolic BP was 153.1\u0026plusmn;20.2 mmHg. Mean arterial pressure, systolic and diastolic BP following\u003cspan dir=\"RTL\"\u003e\u0026nbsp;\u003c/span\u003eMTN in both groups has been demonstrated in \u003cstrong\u003eFigure 1\u003c/strong\u003e. Minimum and maximum intra-operative pulse recordings were 60\u0026plusmn;12.27 beat per minute (BPM) and 78.15\u0026plusmn;12.67 BPM, respectively. Changes in BP from pre-operative assessment to intra-operative assessment during MTN have been illustrated in \u003cstrong\u003eFigure 2\u003c/strong\u003e for both groups.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.2 Outcome Evaluation\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe distribution of systolic blood pressure in both groups, categorized according to post-operative BNI, is depicted in \u003cstrong\u003eFigure 3\u003c/strong\u003e. The main aim of the analysis was to study the relationship between developing intra-operative HTN and post-operative BNI score, while controlling for the pre-operative BNI score and duration of symptoms. Some other factors that are thought to affect outcomes of MVD such as laterality of symptoms, branches of trigeminal nerve involved, etiology of nerve compression and duration of symptoms prior to surgery were also analyzed [9-11]. Additional univariate analyses of covariance were performed to study the effect of demographic variables such as age, sex, history of HTN, history of diabetes, smoking status, and obesity on post operative BNI scores.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eFor the analysis, patients were divided into two groups. The first group did not develop intra-operative HTN during MTN, while the second group developed sustained HTN during MTN for few minutes. Initially, we performed a univariate ANCOVA between intraoperative HTN and pre-operative BNI. The results showed no significant difference between the two groups regarding the BNI, thus allowing us to choose the pre-operative BNI as a covariate. Next, we performed HOR, which did not show any significant relationship either. After satisfying both these prerequisites an analysis of covariance performed. This process was repeated for duration of symptoms as the covariate, with post-operative BNI as the outcome.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eIn the first model with preoperative BNI as the covariate variable there was a statistically significant (p=0.021) association between intraoperative HTN and postoperative BNI. A linear regression model for the same showed that patients who experienced intra-operative HTN have a 0.5-point decrease in post operative BNI as compared to patients who do not have intra-operative HTN, thus predicting that intraoperative HTN is associated with a lower postoperative BNI score.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe second model with duration of symptoms as the covariate, also showed a significant association (p=0.007) between intra-operative HTN and post-operative BNI. Similarly, linear regression showed that patients who experienced intra-operative HTN have a 0.6-point decrease in post operative BNI as compared to patients who do not have intra-operative HTN, thus predicting that intraoperative HTN is associated with a lower postoperative BNI score, when controlling for duration of symptoms.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAdditional univariate analyses demonstrated a significant relationship between past medical history of HTN and post operative BNI (p=0.040), while controlling for pre-operative BNI. Further analyses of covariance with pre-operative BNI and duration of symptoms as covariates did not show any significant relationship between age, sex, pre-operative HTN, past medical history of diabetes, obesity, smoking status, laterality of symptoms, branches involved, etiology of compression and duration of symptoms with the post-operative BNI (\u003cstrong\u003eTable 2\u003c/strong\u003e).\u0026nbsp;\u003c/p\u003e"},{"header":"4. Discussion","content":"\u003cp\u003eIn our study of 90 patients, 72 (80%) developed episodes of HTN upon MTN during MVD. These patients had statistically significantly lower post-operative Barrow Neurological Index (BNI) scores and theoretically better outcomes post decompression, even after controlling for pre-operative BNI and duration of symptoms. Additionally, patients with a past medical history of HTN also had lower post-operative BNI scores when compared to patients who did not. The mean post-operative BNI scores was 1.46 for the group that developed intra-operative HTN as opposed to 2 for the group that did not develop HTN during the surgery (p\u0026thinsp;=\u0026thinsp;0.006).\u003c/p\u003e \u003cp\u003eThe classical TCR in humans was first described by Schaller et al. in 1999 during cerebellopontine angle surgery [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Since then, he has defined TCR as a drop in mean arterial blood pressure by more than 20% upon stimulation of the trigeminal nerve complex.\u003csup\u003e12\u003c/sup\u003e To understand the different ways in which the TCR may present, it is important to understand the anatomy and the different trigger points available for the activation of the reflex.\u003c/p\u003e \u003cp\u003eSchaller and his colleagues have further subdivided this reflex into three categories, depending on the anatomical location. The reflex includes the Central, Peripheral, and Ganglion subtype [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. The afferent limb of the TCR is made up by the sensory nerve fibers traveling to the Gasserian ganglion located in the 4th ventricle. However, the afferent limb changes depending on the subtype of TCR (central, peripheral, or ganglion) [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. The efferent limb is made up by the motor nuclei of the Vagus nerve and its parasympathetic nerve fibers. Naturally, the most common effect of activating this response would be a decrease in blood pressure or heart rate, as is seen in classical TCR [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. Review of the literature demonstrates the effects of TCR on both the parasympathetic (PNS) and sympathetic nervous system (SNS). Chen et al. showed that pre-treating with labetalol or anti-cholinergic agents prevented bradycardia and hypertension during balloon compression rhizotomy (BCR) [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. Studies in animal models show that MTN can also lead to an increase in adrenaline release, thus activating the SNS.\u003c/p\u003e \u003cp\u003eAdditionally, HTN during MTN has also been described in radiofrequency thermocoagulation (RFT). Foramen ovale puncture led to an increase in BP and heart rate (HR) in all the patients in a study done by Meng et al. Thermal energy was considerably stronger than electrical energy for causing increases in BP and HR and was found to be directly proportional to the amount of current that is directed at the lesioned site [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. As the frequency of the thermal current increased, the depressor response converted to a stressor response. Additionally, the electrical stimulation and heating during RFT also heated up the C fibers leading to rises in the BP and pulse [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. Additionally, if a patient has lighter anesthesia, the pain of the operation can lead to a severe sympathetic nervous response. Direct stimulation of the trigeminal ganglion may lead to a vasoconstrictive response, thus leading to HTN [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eAs shown by Schaller et al. the TCR has three components and, depending on the component stimulated, may have a different physiologic response [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. Studies have demonstrated that the peripheral variant of the TCR has bradycardia, HTN and bouts of apnea. Whereas a more central manipulation leads to hypotension. Thus, depending on the area and degree of compression, MVD for TN may produce a different type of TCR [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. Most MVD procedures involve MTN near the Gasserian ganglion around Meckel\u0026rsquo;s cave. This ganglion is surrounded by sympathetic and parasympathetic nerve fibers originating from the carotid plexus. This anatomic relationship may explain the variations in the TCR [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. While developing the hypertensive variant of the TCR during MVD is not well studied, it is commonly observed and well-reported during other procedures involving MTN. Additionally, the balance of which the autonomic nervous system gets activated could vary from patient to patient making the response variable and unreliable.\u003c/p\u003e \u003cp\u003eA study performed by Liu et al. showed that more than 80% of patients experienced hypertension, during trigeminal nerve combing [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. Additionally, these patients had an increase in the level of epinephrine, inferring that the increase in BP was directly related to the activation of the sympathetic nervous system. The authors concluded that the increased HTN was a result of vasoconstriction secondary to the sympathetic nervous system. Most interestingly, Patients who did not develop HTN during combing did not benefit from the procedure. They hypothesized, that the TN in these patients was likely due to a central complex, rather than peripheral compression syndrome. Further support for this theory was strengthened by the underlying diagnosis of multiple sclerosis (MS) in these sub-set of patients. Thus, these patients would not have benefited from the MVD. The major takeaway from their study was that it is important to consider this factor and be prepared for this occurrence, as such high increases in blood pressure can lead to severe intraoperative morbidity. Finally, one must be careful to avoid intracerebral hemorrhage, during MVD with such high blood pressures [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. Like our results of improved outcomes in patients with blood pressure spikes, Zuo et al. reported that developing intra-operative HTN during BCR meant that the compression was successful, and further supported the use of continuous intra-operative blood pressure monitoring [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eWhile most surgeons believe that it is best to prevent TCR rather than treat it intra-operatively, due to its various forms, pre-treatment with atropine is not recommended. However, there are limiting certain risk factors that can decrease the incidence of TCR. The best strategy is to prevent these risk factors and thus prevent the TCR from occurring.\u003csup\u003e6\u003c/sup\u003e In addition, the anesthesiology team should be alerted when the neurosurgeon is MTN and the neurosurgeon must always use gentle retraction while doing so. Finally, acknowledging the prognostic significance of intraoperative HTN subsequent to MTN, it is recommended to explore alternative neurovascular conflicts in patients who do not manifest this response. This ensures a thorough investigation, confirming that the surgeon has considered all potential sites for decompression in the treatment of trigeminal nerve.\u003c/p\u003e \u003cp\u003e \u003cb\u003eLimitations\u003c/b\u003e \u003c/p\u003e \u003cp\u003eThe major limitation of this study is the small sample size and retrospective nature of this study. While our results were statistically significant, to deme their clinical significance and influence on surgical decision-making, a larger sample size and prospective studies must be conducted to determine the true effect of developing intra-operative HTN on outcomes of the procedure.\u003c/p\u003e"},{"header":"5. Conclusion","content":"\u003cp\u003eAs previously believed, the TCR exists in many forms. It is important to know the different anatomical locations of the trigeminal complex to understand what variant of the reflex will be evoked during surgery. The development of intra-operative HTN during MTN, regardless of either pre-operative BNI pain scale or duration of symptoms, may lead to better post-operative BNI scores and outcomes. As a result, the occurrence of intraoperative HTN subsequent to MTN may function as a prognostic indicator for surgical outcomes in patients with TN. Furthermore, it is recommended to conduct additional investigations into potential neurovascular conflicts in patients not manifesting intraoperative HTN following MTN. Further research is warranted to investigate the mechanisms underlying this association.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eFunding:\u0026nbsp;\u003c/strong\u003eNone\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflicts of interest/Competing interests:\u0026nbsp;\u003c/strong\u003eAll authors certify that they have no affiliations with or involvement in any organization or entity with any financial interest (such as honoraria; educational grants; participation in speakers\u0026apos; bureaus; membership, employment, consultancies, stock ownership, or other equity interest; and expert testimony or patent-licensing arrangements), or non-financial interest (such as personal or professional relationships, affiliations, knowledge or beliefs) in the subject matter or materials discussed in this manuscript.\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics approval:\u0026nbsp;\u003c/strong\u003eAll procedures performed in this study involving human participants were in accordance with the ethical standards and the 1964 Helsinki Declaration and its later amendments or comparable ethical standards and approved by the Institutional Review Board of Cleveland Clinic (IRB number: 23-327, 329/2023).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eInformed consent:\u0026nbsp;\u003c/strong\u003eInformed consent was obtained from all individual participants included in the study.\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent to participate:\u0026nbsp;\u003c/strong\u003eInformed consent to participate in this study was obtained from participants included in the study.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and material:\u0026nbsp;\u003c/strong\u003eThe authors confirm that the data supporting the findings of this study are available within the article.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eGreen, A., et al., \u003cem\u003ePost-herpetic trigeminal neuralgia treated with deep brain stimulation.\u003c/em\u003e Journal of clinical neuroscience, 2003. \u003cstrong\u003e10\u003c/strong\u003e(4): p. 512-514.\u003c/li\u003e\n\u003cli\u003eEsmaeilzadeh, M., et al., \u003cem\u003eWhen the nerve keeps firing: an institutional experience and systematic review on delayed response after microvascular decompression for trigeminal neuralgia.\u003c/em\u003e Neurological Sciences, 2023: p. 1-10.\u003c/li\u003e\n\u003cli\u003eChowdhury, T., R.B. Cappellani, and B. Schaller, \u003cem\u003eChronic trigemino-cardiac reflex in patient with orbital floor fracture: role of surgery and first description.\u003c/em\u003e Journal of Neurosurgical Anesthesiology, 2014. \u003cstrong\u003e26\u003c/strong\u003e(1): p. 91-92.\u003c/li\u003e\n\u003cli\u003eGorini, C., et al., \u003cem\u003eEndogenous inhibition of the trigeminally evoked neurotransmission to cardiac vagal neurons by muscarinic acetylcholine receptors.\u003c/em\u003e Journal of neurophysiology, 2010. \u003cstrong\u003e104\u003c/strong\u003e(4): p. 1841-1848.\u003c/li\u003e\n\u003cli\u003eShibao, S., et al., \u003cem\u003eThe trigeminocardiac reflex during the anterior transpetrosal approach.\u003c/em\u003e World neurosurgery, 2017. \u003cstrong\u003e106\u003c/strong\u003e: p. 939-944.\u003c/li\u003e\n\u003cli\u003eMeuwly, C., et al., \u003cem\u003eTrigeminal cardiac reflex: new thinking model about the definition based on a literature review.\u003c/em\u003e Medicine, 2015. \u003cstrong\u003e94\u003c/strong\u003e(5).\u003c/li\u003e\n\u003cli\u003eKouz, K., et al., \u003cem\u003eIntraoperative hypotension: Pathophysiology, clinical relevance, and therapeutic approaches.\u003c/em\u003e Indian journal of anaesthesia, 2020. \u003cstrong\u003e64\u003c/strong\u003e(2): p. 90.\u003c/li\u003e\n\u003cli\u003eSchaller, B., \u003cem\u003eTrigemino-cardiac reflex during microvascular trigeminal decompression in cases of trigeminal neuralgia.\u003c/em\u003e Journal of neurosurgical anesthesiology, 2005. \u003cstrong\u003e17\u003c/strong\u003e(1): p. 45-48.\u003c/li\u003e\n\u003cli\u003eCheng, J., et al., \u003cem\u003eNerve atrophy in trigeminal neuralgia due to neurovascular compression and its association with surgical outcomes after microvascular decompression.\u003c/em\u003e Acta Neurochirurgica, 2017. \u003cstrong\u003e159\u003c/strong\u003e: p. 1699-1705.\u003c/li\u003e\n\u003cli\u003eLoayza, R., et al., \u003cem\u003eOutcome after microvascular decompression for trigeminal neuralgia in a single center\u0026mdash;relation to sex and severity of neurovascular conflict.\u003c/em\u003e Acta Neurochirurgica, 2023: p. 1-8.\u003c/li\u003e\n\u003cli\u003eDuan, Y., et al., \u003cem\u003eDegree of distal trigeminal nerve atrophy predicts outcome after microvascular decompression for Type 1a trigeminal neuralgia.\u003c/em\u003e Journal of neurosurgery, 2015. \u003cstrong\u003e123\u003c/strong\u003e(6): p. 1512-1518.\u003c/li\u003e\n\u003cli\u003eMeuwly, C., et al., \u003cem\u003eDefinition and diagnosis of the trigeminocardiac reflex: a grounded theory approach for an update.\u003c/em\u003e Frontiers in neurology, 2017. \u003cstrong\u003e8\u003c/strong\u003e: p. 533.\u003c/li\u003e\n\u003cli\u003eSchaller, B., \u003cem\u003eTrigeminocardiac reflex: a clinical phenomenon or a new physiological entity?\u003c/em\u003e Journal of neurology, 2004. \u003cstrong\u003e251\u003c/strong\u003e: p. 658-665.\u003c/li\u003e\n\u003cli\u003eChen, C.-Y., et al., \u003cem\u003eComparison of the effects of atropine and labetalol on trigeminocardiac reflex-induced hemodynamic alterations during percutaneous microballoon compression of the trigeminal ganglion.\u003c/em\u003e Acta Anaesthesiologica Taiwanica, 2012. \u003cstrong\u003e50\u003c/strong\u003e(4): p. 153-158.\u003c/li\u003e\n\u003cli\u003eMeng, Q., et al., \u003cem\u003eCardiovascular responses during percutaneous radiofrequency thermocoagulation therapy in primary trigeminal neuralgia.\u003c/em\u003e Journal of Neurosurgical Anesthesiology, 2008. \u003cstrong\u003e20\u003c/strong\u003e(2): p. 131-135.\u003c/li\u003e\n\u003cli\u003eKehler, C.H., et al., \u003cem\u003eBlood pressure response during percutaneous rhizotomy for trigeminal neuralgia.\u003c/em\u003e Neurosurgery, 1982. \u003cstrong\u003e10\u003c/strong\u003e(2): p. 200-202.\u003c/li\u003e\n\u003cli\u003eMcCulloch, P.F., K.M. Faber, and W.M. Panneton, \u003cem\u003eElectrical stimulation of the anterior ethmoidal nerve produces the diving response.\u003c/em\u003e Brain research, 1999. \u003cstrong\u003e830\u003c/strong\u003e(1): p. 24-31.\u003c/li\u003e\n\u003cli\u003eBorghei-Razavi, H., et al., \u003cem\u003eUnusual Appearance of Trigemino-Cardiac Reflex During Cerebellopontine Angle Surgery.\u003c/em\u003e World Neurosurgery, 2018. \u003cstrong\u003e112\u003c/strong\u003e: p. 298-299.\u003c/li\u003e\n\u003cli\u003eLiu, J., et al., \u003cem\u003eRelationship between arterial blood pressure during trigeminal nerve combing and surgical outcome in patients with trigeminal neuralgia.\u003c/em\u003e World Neurosurgery, 2020. \u003cstrong\u003e137\u003c/strong\u003e: p. e98-e105.\u003c/li\u003e\n\u003cli\u003eZuo, Y., et al., \u003cem\u003eContinuous Intra-Arterial Blood Pressure Monitoring Improves the Efficiency of Percutaneous Balloon Compression of the Trigeminal Ganglion for Trigeminal Neuralgia.\u003c/em\u003e Pain Research and Management, 2022. \u003cstrong\u003e2022\u003c/strong\u003e.\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Tables","content":"\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" align=\"\" width=\"751\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd width=\"100%\" colspan=\"4\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eTable 1:\u0026nbsp;\u003c/strong\u003eComparison of demographic and clinical features between the two groups in the study population\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"22.37017310252996%\" valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"28.495339547270305%\" valign=\"top\"\u003e\n \u003cp\u003eIntra-operative HTN (n=72)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25.03328894806924%\" valign=\"top\"\u003e\n \u003cp\u003eNo Intra-operative HTN (n=18)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"24.101198402130493%\" valign=\"top\"\u003e\n \u003cp\u003ep-value\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"22.37017310252996%\" valign=\"top\"\u003e\n \u003cp\u003eSex\u003c/p\u003e\n \u003cp\u003eMale\u003c/p\u003e\n \u003cp\u003eFemale\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"28.495339547270305%\" valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e24 (33.3%)\u003c/p\u003e\n \u003cp\u003e48 (66.7%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25.03328894806924%\" valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e8 (8.6%)\u003c/p\u003e\n \u003cp\u003e10 (10.8%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"24.101198402130493%\" valign=\"top\"\u003e\n \u003cp\u003e0.378\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"22.37017310252996%\" valign=\"top\"\u003e\n \u003cp\u003eAge\u003csup\u003e#\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"28.495339547270305%\" valign=\"top\"\u003e\n \u003cp\u003e65 years (26-83 years)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25.03328894806924%\" valign=\"top\"\u003e\n \u003cp\u003e60 years (34-74 years)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"24.101198402130493%\" valign=\"top\"\u003e\n \u003cp\u003e0.073\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"22.37017310252996%\" valign=\"top\"\u003e\n \u003cp\u003ePMH of HTN\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"28.495339547270305%\" valign=\"top\"\u003e\n \u003cp\u003e30 (41.7%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25.03328894806924%\" valign=\"top\"\u003e\n \u003cp\u003e5 (5.4%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"24.101198402130493%\" valign=\"top\"\u003e\n \u003cp\u003e0.280\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"22.37017310252996%\" valign=\"top\"\u003e\n \u003cp\u003ePMH of DM\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"28.495339547270305%\" valign=\"top\"\u003e\n \u003cp\u003e9 (23.6%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25.03328894806924%\" valign=\"top\"\u003e\n \u003cp\u003e1 (1.1%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"24.101198402130493%\" valign=\"top\"\u003e\n \u003cp\u003e0.680\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"22.37017310252996%\" valign=\"top\"\u003e\n \u003cp\u003eObesity\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"28.495339547270305%\" valign=\"top\"\u003e\n \u003cp\u003e17 (23.6%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25.03328894806924%\" valign=\"top\"\u003e\n \u003cp\u003e7 (7.5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"24.101198402130493%\" valign=\"top\"\u003e\n \u003cp\u003e0.235\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"22.37017310252996%\" valign=\"top\"\u003e\n \u003cp\u003eSmoking\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"28.495339547270305%\" valign=\"top\"\u003e\n \u003cp\u003e33 (45.8%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25.03328894806924%\" valign=\"top\"\u003e\n \u003cp\u003e9 (9.7%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"24.101198402130493%\" valign=\"top\"\u003e\n \u003cp\u003e0.751\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"22.37017310252996%\" valign=\"top\"\u003e\n \u003cp\u003eType of Compression\u0026nbsp;\u003c/p\u003e\n \u003cp\u003eArterial\u0026nbsp;\u003c/p\u003e\n \u003cp\u003eVenous\u0026nbsp;\u003c/p\u003e\n \u003cp\u003eMixed\u0026nbsp;\u003c/p\u003e\n \u003cp\u003eNerve\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"28.495339547270305%\" valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e49 (68.1%)\u003c/p\u003e\n \u003cp\u003e14 (19.4%)\u003c/p\u003e\n \u003cp\u003e5 (6.9%)\u003c/p\u003e\n \u003cp\u003e4 (5.6%) \u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25.03328894806924%\" valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e11 (7.5%)\u003c/p\u003e\n \u003cp\u003e3 (3.2%)\u003c/p\u003e\n \u003cp\u003e4 (4.3%)\u003c/p\u003e\n \u003cp\u003e0\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"24.101198402130493%\" valign=\"top\"\u003e\n \u003cp\u003e0.210\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"22.37017310252996%\" valign=\"top\"\u003e\n \u003cp\u003eSymptom Laterality\u0026nbsp;\u003c/p\u003e\n \u003cp\u003eRight\u0026nbsp;\u003c/p\u003e\n \u003cp\u003eLeft\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"28.495339547270305%\" valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e38 (52.8%)\u003c/p\u003e\n \u003cp\u003e33 (45.8%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25.03328894806924%\" valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e11 (11.8%)\u003c/p\u003e\n \u003cp\u003e7 (7.5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"24.101198402130493%\" valign=\"top\"\u003e\n \u003cp\u003e0.745\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"22.37017310252996%\" valign=\"top\"\u003e\n \u003cp\u003eBranch\u0026nbsp;\u003c/p\u003e\n \u003cp\u003eV1\u003c/p\u003e\n \u003cp\u003eV2\u003c/p\u003e\n \u003cp\u003eV3\u003c/p\u003e\n \u003cp\u003eMixed\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"28.495339547270305%\" valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e1 (1.4%)\u003c/p\u003e\n \u003cp\u003e24 (33.3%)\u003c/p\u003e\n \u003cp\u003e20 (27.8%)\u003c/p\u003e\n \u003cp\u003e27 (37.5)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25.03328894806924%\" valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e1 (1.1%)\u003c/p\u003e\n \u003cp\u003e2 (2.2%)\u003c/p\u003e\n \u003cp\u003e3 (6%)\u003c/p\u003e\n \u003cp\u003e9 (9.7%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"24.101198402130493%\" valign=\"top\"\u003e\n \u003cp\u003e0.231\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"22.37017310252996%\" valign=\"top\"\u003e\n \u003cp\u003ePre-operative HTN\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"28.495339547270305%\" valign=\"top\"\u003e\n \u003cp\u003e21 (29.2%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25.03328894806924%\" valign=\"top\"\u003e\n \u003cp\u003e4 (4.3%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"24.101198402130493%\" valign=\"top\"\u003e\n \u003cp\u003e0.556\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"22.37017310252996%\" valign=\"top\"\u003e\n \u003cp\u003ePre-operative BNI\u003csup\u003e#\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"28.495339547270305%\" valign=\"top\"\u003e\n \u003cp\u003e5 (3-5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25.03328894806924%\" valign=\"top\"\u003e\n \u003cp\u003e4 (3-5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"24.101198402130493%\" valign=\"top\"\u003e\n \u003cp\u003e0.128\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"22.37017310252996%\" valign=\"top\"\u003e\n \u003cp\u003ePost-operative BNI\u003csup\u003e#\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"28.495339547270305%\" valign=\"top\"\u003e\n \u003cp\u003e1 (1-4)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25.03328894806924%\" valign=\"top\"\u003e\n \u003cp\u003e2 (1-4)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"24.101198402130493%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.006\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"22.37017310252996%\" valign=\"top\"\u003e\n \u003cp\u003eLength of symptoms \u003csup\u003e#\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"28.495339547270305%\" valign=\"top\"\u003e\n \u003cp\u003e36 days (1-360 days)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25.03328894806924%\" valign=\"top\"\u003e\n \u003cp\u003e36 days (2-240 days)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"24.101198402130493%\" valign=\"top\"\u003e\n \u003cp\u003e0.266\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e# Continuous data is presented as median (Range)\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAbbreviations. BNI:\u0026nbsp;Barrow Neurological Institute Pain Scale, HTN: Hypertension, PMH: Past medical history, DM: Diabetes Mellitus\u003c/p\u003e\n\u003cp\u003eBoldface type indicates statistical significance (p \u0026lt; 0.05).\u0026nbsp;\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"582\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd width=\"100%\" colspan=\"3\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eTable 2\u003c/strong\u003e: Relationship between patient factors and post-operative BNI\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"32.98969072164948%\" valign=\"top\"\u003e\n \u003cp\u003eFixed Factor\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"67.01030927835052%\" colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003ep-value\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"32.98969072164948%\" valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"28.8659793814433%\" valign=\"top\"\u003e\n \u003cp\u003e*Pre-operative BNI\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"38.144329896907216%\" valign=\"top\"\u003e\n \u003cp\u003e*Duration of symptoms\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"32.98969072164948%\" valign=\"top\"\u003e\n \u003cp\u003eIntra-operative HTN\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"28.8659793814433%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.021\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"38.144329896907216%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.007\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"32.98969072164948%\" valign=\"top\"\u003e\n \u003cp\u003eSex\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"28.8659793814433%\" valign=\"top\"\u003e\n \u003cp\u003e0.815\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"38.144329896907216%\" valign=\"top\"\u003e\n \u003cp\u003e0.695\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"32.98969072164948%\" valign=\"top\"\u003e\n \u003cp\u003ePMH of HTN\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"28.8659793814433%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.040\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"38.144329896907216%\" valign=\"top\"\u003e\n \u003cp\u003e0.066\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"32.98969072164948%\" valign=\"top\"\u003e\n \u003cp\u003eImmediate pre-operative HTN\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"28.8659793814433%\" valign=\"top\"\u003e\n \u003cp\u003e0.865\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"38.144329896907216%\" valign=\"top\"\u003e\n \u003cp\u003e0.862\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"32.98969072164948%\" valign=\"top\"\u003e\n \u003cp\u003eLaterality\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"28.8659793814433%\" valign=\"top\"\u003e\n \u003cp\u003e0.528\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"38.144329896907216%\" valign=\"top\"\u003e\n \u003cp\u003e0.581\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"32.98969072164948%\" valign=\"top\"\u003e\n \u003cp\u003eBranch\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"28.8659793814433%\" valign=\"top\"\u003e\n \u003cp\u003e0.821\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"38.144329896907216%\" valign=\"top\"\u003e\n \u003cp\u003e0.768\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"32.98969072164948%\" valign=\"top\"\u003e\n \u003cp\u003ePMH of DM\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"28.8659793814433%\" valign=\"top\"\u003e\n \u003cp\u003e0.275\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"38.144329896907216%\" valign=\"top\"\u003e\n \u003cp\u003e0.361\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"32.98969072164948%\" valign=\"top\"\u003e\n \u003cp\u003eObesity\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"28.8659793814433%\" valign=\"top\"\u003e\n \u003cp\u003e0.622\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"38.144329896907216%\" valign=\"top\"\u003e\n \u003cp\u003e0.568\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"32.98969072164948%\" valign=\"top\"\u003e\n \u003cp\u003eSmoking\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"28.8659793814433%\" valign=\"top\"\u003e\n \u003cp\u003e0.685\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"38.144329896907216%\" valign=\"top\"\u003e\n \u003cp\u003e0.472\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"32.98969072164948%\" valign=\"top\"\u003e\n \u003cp\u003eType of compression\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"28.8659793814433%\" valign=\"top\"\u003e\n \u003cp\u003e0.507\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"38.144329896907216%\" valign=\"top\"\u003e\n \u003cp\u003e0.518\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"32.98969072164948%\" valign=\"top\"\u003e\n \u003cp\u003eAge\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"28.8659793814433%\" valign=\"top\"\u003e\n \u003cp\u003e0.332\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"38.144329896907216%\" valign=\"top\"\u003e\n \u003cp\u003e0.368\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"32.98969072164948%\" valign=\"top\"\u003e\n \u003cp\u003eDuration of symptoms\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"28.8659793814433%\" valign=\"top\"\u003e\n \u003cp\u003e0.252\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"38.144329896907216%\" valign=\"top\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u0026nbsp;*Covariates in each individual univariate model.\u003c/p\u003e\n\u003cp\u003eAbbreviations. BNI:\u0026nbsp;Barrow Neurological Institute Pain Scale, HTN: Hypertension, PMH: Past medical history, DM: Diabetes Mellitus\u003c/p\u003e\n\u003cp\u003eBoldface type indicates statistical significance (p \u0026lt; 0.05).\u0026nbsp;\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Trigeminal nerve, Hypertension, Trigeminocardiac reflex, microvascular decompression, pain","lastPublishedDoi":"10.21203/rs.3.rs-3949568/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-3949568/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eObjective:\u003c/strong\u003e The trigeminocardiac reflex (TCR) has traditionally been characterized by a sudden decrease in heart rate, asystole, or hypotension during the manipulation of the trigeminal nerve (MTN) or its branches. While this classical TCR is well-documented, there is limited literature on alternative forms of TCR, such as the development of intraoperative hypertension (HTN) or tachycardia, and the underlying pathogenesis. Furthermore, a gap exists in understanding the correlation between intraoperative blood pressure readings and postoperative outcomes, particularly regarding pain relief in patients with trigeminal neuralgia (TN). Our study aims to examine intraoperative blood pressure trends during microvascular decompression (MVD) for TN and assess their impact on postoperative outcomes.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods:\u003c/strong\u003e We selected 90 patients who underwent MVD for TN treatment. Blood pressure and heart rate were recorded both preoperatively and during the procedure, specifically during the MTN period, using an arterial line. The Barrow Neurological Institute (BNI) Pain Scale was calculated for all patients both pre- and post-operatively to evaluate pain relief after surgery.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults:\u003c/strong\u003e The mean age of the patients was 61.0±12.35 years, with 64.4% being females. Classical TCR (hypotension) was observed in only 2.2% of patients, whereas 80% of patients developed hypertension (≥140/90) during MTN. The mean preoperative systolic blood pressure was 128 ± 22.25, and the mean intraoperative systolic blood pressure during MTN was 153.1± 20.2. An analysis of covariance, utilizing either preoperative BNI or duration of symptoms as covariate variables, revealed a statistically significant association between intraoperative HTN and postoperative BNI. A linear regression model demonstrated that intraoperative HTN following MTN significantly predicted a lower postoperative BNI score (p=0.006).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusions:\u003c/strong\u003e Intraoperative HTN during MTN, an observed yet underexplored phenomenon, demonstrated a correlation with improved postoperative outcomes. Furthermore, it is recommended to conduct additional investigations into potential neurovascular conflicts in patients not manifesting intraoperative HTN following MTN. A comprehensive understanding of TCR, encompassing its various forms, is vital for optimizing surgical management. This study underscores the imperative for further research to unravel the mechanisms linking intraoperative HTN to surgical outcomes in TN patients.\u003c/p\u003e","manuscriptTitle":"Intra-operative Hypertension as a Predictor of Surgical Outcomes in Microvascular Decompression Surgery for Trigeminal Neuralgia","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-02-21 17:59:23","doi":"10.21203/rs.3.rs-3949568/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"bad814c8-2f88-4ad6-b21b-2c68416fc399","owner":[],"postedDate":"February 21st, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2024-03-05T19:32:40+00:00","versionOfRecord":[],"versionCreatedAt":"2024-02-21 17:59:23","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-3949568","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-3949568","identity":"rs-3949568","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}