Isolated brain stem death: case report with demonstration of preserved cerebral perfusion in 99-TC biscicinate brain death study.

Isolated brain stem death: case report with demonstration of preserved cerebral perfusion in 99-TC biscicinate brain death study. | 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 Case Report Isolated brain stem death: case report with demonstration of preserved cerebral perfusion in 99-TC biscicinate brain death study. Ghazal Shadmani, Amin Haghighat Jahromi This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4889425/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 Background The brainstem anatomy is complex, and the diagnosis of brain death (BD) in patients with isolated catastrophic posterior fossa lesions may pose a diagnostic dilemma. This is because all brainstem reflexes (which are the basis of neurologic examination) are lost; however, from an anatomical standpoint, the mesopontine tegmental reticular formation (MPT-RF) can theoretically be intact in patients with brainstem death. Moreover, supratentorial perfusion and electrical activity may be present. The significance of preserved supratentorial perfusion in the context of isolated catastrophic brainstem damage is not clear. We report the outcomes of an adult patient with catastrophic basilar artery thrombosis with preserved cerebral perfusion on brain scintigraphy. Patient presentation: A 47-year-old woman presented in an obtunded state and was found to have distal basilar artery thrombosis. After mechanical thrombectomy, her condition deteriorated, and a head CT scan revealed brain stem edema. Subsequently, brain death was suspected, and a 99mTc bicisate brain blood flow study was performed, which revealed the complete absence of blood flow to the cerebellum despite intact circulation to the cerebral hemispheres. Accordingly, life support continued. The next day, the patient was declared clinically brain dead with no follow-up imaging. Conclusions The significance of preserved supratentorial brain perfusion in the context of isolated catastrophic posterior fossa lesions is unclear. In keeping with a few additional cases in the literature, preserved supratentorial perfusion in our patient quickly evolved. The complex brain stem anatomy warrants further ancillary tests for the confirmation of brain death in patients with isolated fatal posterior fossa lesions. Nuclear Medicine & Medical Imaging Neurology Brain death Brainstem death 99mTc bicisate brain blood flow study basilar artery occlusion Figures Figure 1 Figure 2 Figure 3 Figure 4 Introduction The fundamental concept of brain death (BD) involves a comatose state and the irreversible loss of spontaneous respiration. Before a diagnosis is made, it is crucial to establish the underlying disorder that results in brain injury and to rule out confounders and reversible causes of coma and apnea, such as drug intoxication, hypothermia, acute metabolic disturbances, and neuromuscular disorders [ 1 , 2 ]. Brain death (BD) is primarily a clinical diagnosis, and whenever a patient meets the two aforementioned criteria, they can be considered dead from a biological standpoint [ 3 ]. Even though the definition of BD is the same across different countries, the criteria for its determination and the need for ancillary tests, such as EEG and brain perfusion scintigraphy, are not uniform worldwide. In some countries, such as the UK and several states in the USA, the presence of coma and proven apnea, in combination with the loss of brainstem reflexes, are sufficient for the diagnosis of BD, regardless of the location of the brain lesion, and ancillary tests are not needed. Case reports of patients with infratentorial lesions exhibiting clinical signs of brain death (BD) but with preserved EEG activity in the cerebral cortex necessitate stricter criteria for diagnosing brain death in patients with infratentorial lesions [ 4 , 5 ]. The debate centers around whether the whole brain or the brainstem should be considered dead as the criterion for brain death [ 6 , 7 ]. Owing to the complex anatomy of the brainstem, which contains multiple critical nuclei (Fig. 1), insults to this region can cause catastrophic sequelae, resulting in the loss of all brainstem reflexes. However, the brain cortex may still be viable, and the reticular activating system, located posterior to the pons, may remain uninjured, at least at the beginning of the injury, as evidenced by preserved electrical activity on EEG or VEP or preserved perfusion on CT angiography or brain scintigraphy. As such, this situation may pose a diagnostic dilemma since these patients fulfill the clinical criteria for brain death, but ancillary tests may reveal perfusion and electrical activity in the brain cortex, which argues against the definition of brain death. Herein, we present the clinical course, imaging, and outcome of a patient with basilar artery thrombosis, no brainstem reflexes, and preserved cortical brain perfusion on brain perfusion scintigraphy. Case report A 47-year-old woman was transported to the emergency department in an obtunded state after the sudden onset of right facial droop and aphasia. Her history was notable for 1 week of migraines and recent heavy loose tobacco use via pipe "all day". She had no history of seizures. In the emergency department, she had continuous seizures, quickly decompensated, and was intubated. Her natural institutional health stroke score (NIHSS) was at least 31. After the family was able to confirm that her last known normal was 3 hours prior, she received tPA and Keppra. A head CT revealed a dense basilar artery suggestive of thrombosis (Fig. 2). A head CTA was obtained and revealed distal basilar occlusion extending into the right P1 (Fig. 3). She underwent mechanical thrombectomy and was TICI 2B after 2 passes. The patient was then taken to the neuroICU after the procedure, and due to poor awakening from anesthesia, a head CT was obtained. Head CT revealed increased brainstem edema as well as obstructive hydrocephalus with decreased size of the 4th ventricle and increased sizes of the 3rd and lateral ventricles. Upon neurosurgical evaluation, she was not considered a good candidate for possible intervention because of a very poor neurologic exam and recent tPA administration. Follow-up head CT revealed evolving edema and infarction in the bilateral cerebellar hemispheres, brainstem, and right occipital lobe. The patient’s clinical condition continued to deteriorate. The patient clinically appeared to be ‘‘brain dead’’, but no formal apnea test was ever performed. A confirmatory 99mTc bicisate brain blood flow study was performed (Fig. 4). Imaging was performed immediately and 20 minutes after the administration of 99mTc bicisate. Despite the complete absence of blood flow to the posterior fossa/cerebellum (arrows), there was diffuse uptake in both cerebral hemispheres. Medicolegally, the patient’s condition did not meet the definition of brain death; therefore, life support was continued. One-day follow-up brain CT revealed extensive cytotoxic edema involving the brainstem, bilateral cerebellar hemispheres, and occipital lobes as well as the development of upper transtentorial and descending tonsillar herniation and obstructive hydrocephalus. The same day, the patient was declared clinically brain dead with no follow-up images. The potential for organ donation was discussed with her family, who confirmed that this would respect the patient’s expressed wishes. Her kidneys and liver recovered successfully. Autopsy was not performed. Discussion An isolated catastrophic brain stem lesion leading to “brain death” scenario is uncommon. From a series of 161 BD cases, Varela et al. reported three cases with isolated posterior fossa injury, accounting for a 1.9% prevalence among BD cases [ 8 ]. Isolated brainstem lesions can be observed in basilar artery thrombosis, such as in our case, subarachnoid hemorrhage, massive trauma, and complications of posterior fossa surgery [ 9 – 11 ]. There are two other mechanisms that may impair posterior fossa function: first, large supratentorial lesions (e.g., ischemia, trauma, hemorrhage) with progressive transtentorial herniation and gradual loss of brainstem function. The second mechanism is diffuse brain parenchymal injury, such as hypoxia after cardiac arrest [ 7 ]. Both of these mechanisms are associated with loss of function in both the supratentorial brain parenchyma and the brainstem, meeting the criteria for whole-brain death. Hence, in patients with fatal supratentorial lesions and in the absence of confounders, brain death can be reliably diagnosed on the basis of a thorough neurological examination. On the other hand, in patients with isolated catastrophic posterior fossa lesions, even though all brainstem reflexes are lost, the supratentorial brain is still viable. Furthermore, from an anatomical standpoint, the brainstem reflexes and the mesopontine tegmental reticular formation are located in different topographical regions, with the theoretical possibility of impaired brainstem reflexes while retaining reticular formation function—a situation known as total locked-in syndrome [ 12 ]. As such, diagnosing brain death in patients with fatal isolated posterior fossa lesions may be challenging because of the need for a thorough neurological examination. However, in our patient, the injury was extensive and involved the posterior midbrain. Preserved supratentorial perfusion in the absence of infratentorial perfusion has been described in the literature in patients with catastrophic isolated posterior fossa lesions [ 13 ]. It has also been described in a patient with fatal subarachnoid hemorrhage without isolated posterior fossa lesions [ 14 ]. The significance of preserved supratentorial perfusion in the context of catastrophic brainstem damage is not clear. All these patients were ultimately declared brain dead within a few days, with or without further imaging. The inevitable supratentorial brain tissue injury can be explained by occlusion of the aqueduct secondary to brainstem edema, leading to progressive supratentorial hydrocephalus and gradual loss of supratentorial brain perfusion. Moreover, ongoing brain edema, resulting in the collapse of the vein of Galen, exacerbates this process, eventually leading to the inability of blood pressure to compensate for the disease. In accordance with prior case reports, our case showed the inevitability of the process, which eventually led to the declaration of brain death. Conclusion The significance of preserved supratentorial brain perfusion in the context of isolated catastrophic posterior fossa lesions is not clear. In keeping with a few additional cases in the literature, preserved supratentorial perfusion in our patient quickly evolved. The complex brain stem anatomy warrants further ancillary tests for the confirmation of brain death in patients with isolated fatal posterior fossa lesions. Declarations Consent to publish: The patient's next of kin (her adult daughter) was contacted by our clinic and provided consent for her mother's case to be reported in a medical journal. References Varelas PN, Lewis A (2016) Modern Approach to Brain Death. Semin Neurol 36:625–630. https://doi.org/10.1055/s-0036-1592317 Rizvi T, Batchala P, Mukherjee S (2018) Brain Death: Diagnosis and Imaging Techniques. Seminars in Ultrasound, CT and MRI. ;39:515–29. https://doi.org/10.1053/j.sult.2018.01.006 Wijdicks EFM (2010) The case against confirmatory tests for determining brain death in adults. Neurology 75:77–83. https://doi.org/10.1212/WNL.0b013e3181e62194 DARBY J, YONAS H, BRENNER RP (1987) Brainstem death with persistent EEG activity Evaluation by xenon-enhanced computed tomography. Crit Care Med 15:519–521 Ferbert A, Buchner H, Ringelstein EB, Hacke W ISOLATED BRAIN-STEM DEATH. CASE REPORT WITH DEMONSTRATION OF PRESERVED VISUAL EVOKED POTENTIALS (VEPs) Discussion. n.d Machado C (2022) Brain Death Diagnosis in Primary Posterior Fossa Lesions. Neurol India 70:670–675. https://doi.org/DOI: 10.4103/0028-3886.344634 Walter U, Fernández-Torre JL, Kirschstein T, Laureys S (2018) When is brainstem death brain death? The case for ancillary testing in primary infratentorial brain lesion. Clin Neurophysiol 129:2451–2465. https://doi.org/10.1016/j.clinph.2018.08.009 Varelas PN, Brady P, Rehman M, Afshinnik A, Mehta C, Abdelhak T et al (2017) Primary Posterior Fossa Lesions and Preserved Supratentorial Cerebral Blood Flow: Implications for Brain Death Determination. Neurocrit Care 27:407–414. https://doi.org/10.1007/s12028-017-0442-3 Zwarts MJ, Kornips FHMVO (2001) Clinical Brainstem Death with Preserved Electroencephalographic Activity and Visual Evoked Response. Arch Neurol 58:1010. https://doi.org/10.1016/0032-5910(72)80020-2 Ogata J, Imakita MYC (1988) Primary brainstem death: a clinico-pathological study. J Neurol Neurosurg Psychiatry 51:646–650 Schmidt MQ, Schraml FV (2017) Absent Cerebellar Circulation with Intact Cerebral Blood Flow on a 99mTc Bicisate Brain Death Study. Clin Nucl Med 42:983–984. https://doi.org/10.1097/RLU.0000000000001866 Parvizi J, Damasio AR (2003) Neuroanatomical correlates of brainstem coma. Brain 126:1524–1536. https://doi.org/10.1093/brain/awg166 Varelas PN, Paul Brady P, Rehman M, Afshinnik A, Mehta C, Abdelhak T et al (2017) Primary Posterior Fossa Lesions and Preserved Supratentorial Cerebral Blood Flow: Implications for Brain Death Determination. Neurocrit Care 27:404–407 Schmidt MQ, Schraml FV (2017) Absent Cerebellar Circulation with Intact Cerebral Blood Flow on a 99mTc Bicisate Brain Death Study. Clin Nucl Med 42:983–984. https://doi.org/10.1097/RLU.0000000000001866 Additional Declarations The authors declare no competing interests. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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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-4889425","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Case Report","associatedPublications":[],"authors":[{"id":338356959,"identity":"ffd058ba-6648-4e96-9e6a-933828c05de8","order_by":0,"name":"Ghazal Shadmani","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAwklEQVRIiWNgGAWjYDACCRBRYAMiGQ8wMDATq8UgjQGkmiQth0nQIh/d/PjDD4PziRvOnz9wgKHCOrGBkBbDO8cMDHsMbiduuJEMtOVMOhFaZiQYJPAY3M7dcAPoMMa2w8RoSf9w8I/BudwN5w8DtfwjQou8RI5hM4/BgdwNB4AOY2wgQouBRE4xs4xBcv3MG8kGBxKOpRsTtmVG+uaPbyrsjPnOH3z44EONtSxhWw4g8xIIKQfbQtDQUTAKRsEoGAUAhopF4ONMOVEAAAAASUVORK5CYII=","orcid":"https://orcid.org/0000-0003-1951-8240","institution":"Washington university in Saint louis","correspondingAuthor":true,"prefix":"","firstName":"Ghazal","middleName":"","lastName":"Shadmani","suffix":""},{"id":338357017,"identity":"e4c35533-9261-4758-884c-74e47097c603","order_by":1,"name":"Amin Haghighat Jahromi","email":"","orcid":"","institution":"Washington university in Saint Louis","correspondingAuthor":false,"prefix":"","firstName":"Amin","middleName":"Haghighat","lastName":"Jahromi","suffix":""}],"badges":[],"createdAt":"2024-08-10 00:52:19","currentVersionCode":1,"declarations":{"humanSubjects":true,"vertebrateSubjects":false,"conflictsOfInterestStatement":false,"humanSubjectEthicalGuidelines":true,"humanSubjectConsent":true,"humanSubjectClinicalTrial":true,"humanSubjectCaseReport":true,"vertebrateSubjectEthicalGuidelines":false},"doi":"10.21203/rs.3.rs-4889425/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4889425/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":63057999,"identity":"7830dfae-96ff-4fc8-ab53-32a64a889ad9","added_by":"auto","created_at":"2024-08-22 15:36:31","extension":"tiff","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":170854,"visible":true,"origin":"","legend":"\u003cp\u003eSchematic illustration of anatomical relationship between different brain stem nuclei and mesopontine reticular formation which is shown in gray. The anatomy of the tested brainstem reflexes is shown with distinct colors: yellow (pupillary light reflex), green (vestibulo-ocular reflex), red (corneal reflex, trigeminal nerve), and blue (gag reflex). The area outlined by the dotted red line represents a primary infratentorial (isolated brainstem) lesion resulting in an apneic total locked-in syndrome, clinically mimicking the \"brainstem death\" syndrome.\u003c/p\u003e","description":"","filename":"Figure1.tiff","url":"https://assets-eu.researchsquare.com/files/rs-4889425/v1/b2dd74fba4467ffebb888f7f.tiff"},{"id":63057468,"identity":"f5e699e3-822e-4e6b-ad67-e77bf9849f35","added_by":"auto","created_at":"2024-08-22 15:28:31","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":971527,"visible":true,"origin":"","legend":"\u003cp\u003eAxial(A) and sagittal(B)images of head CT showing dense distal basilar artery (wite arrow), suggestive of thrombosis.\u003c/p\u003e","description":"","filename":"Fig2.png","url":"https://assets-eu.researchsquare.com/files/rs-4889425/v1/bea695cc0955e03abda62146.png"},{"id":63057467,"identity":"d4fd5b42-6a41-4b43-b841-c5c2349beb34","added_by":"auto","created_at":"2024-08-22 15:28:31","extension":"tiff","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":144142,"visible":true,"origin":"","legend":"\u003cp\u003eCoronal head CT angiography shows hypodense clot within the distal basilar artery extending into the first segment of posterior cerebral artery, P1(white arrow).\u003c/p\u003e","description":"","filename":"Figure3.tiff","url":"https://assets-eu.researchsquare.com/files/rs-4889425/v1/7e4d34ac3a6ab6e1c2a8400a.tiff"},{"id":63057465,"identity":"d2ecabc6-cafc-44f6-9b43-7b6815b9a6fd","added_by":"auto","created_at":"2024-08-22 15:28:31","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":958358,"visible":true,"origin":"","legend":"\u003cp\u003eLateral (A) and anterior (B) views of 99mTc bicisate brain scintigraphy shows complete absence of blood flow to the cerebellum (white arrow-heads) with intact circulation to the cerebral hemispheres.\u003c/p\u003e","description":"","filename":"Fig4.png","url":"https://assets-eu.researchsquare.com/files/rs-4889425/v1/be0f88ff1e2a54d9e2389e7d.png"},{"id":63058031,"identity":"7141e628-6ba3-4dce-897e-e6eda943fc33","added_by":"auto","created_at":"2024-08-22 15:36:41","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2964777,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4889425/v1/9d1454d0-f3b7-44e7-87ef-146c96716f55.pdf"}],"financialInterests":"The authors declare no competing interests.","formattedTitle":"\u003cp\u003e\u003cstrong\u003eIsolated brain stem death: case report with demonstration of preserved cerebral perfusion in 99-TC biscicinate brain death study.\u003c/strong\u003e\u003c/p\u003e","fulltext":[{"header":"Introduction","content":"\u003cp\u003eThe fundamental concept of brain death (BD) involves a comatose state and the irreversible loss of spontaneous respiration. Before a diagnosis is made, it is crucial to establish the underlying disorder that results in brain injury and to rule out confounders and reversible causes of coma and apnea, such as drug intoxication, hypothermia, acute metabolic disturbances, and neuromuscular disorders [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. Brain death (BD) is primarily a clinical diagnosis, and whenever a patient meets the two aforementioned criteria, they can be considered dead from a biological standpoint [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. Even though the definition of BD is the same across different countries, the criteria for its determination and the need for ancillary tests, such as EEG and brain perfusion scintigraphy, are not uniform worldwide. In some countries, such as the UK and several states in the USA, the presence of coma and proven apnea, in combination with the loss of brainstem reflexes, are sufficient for the diagnosis of BD, regardless of the location of the brain lesion, and ancillary tests are not needed. Case reports of patients with infratentorial lesions exhibiting clinical signs of brain death (BD) but with preserved EEG activity in the cerebral cortex necessitate stricter criteria for diagnosing brain death in patients with infratentorial lesions [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe debate centers around whether the whole brain or the brainstem should be considered dead as the criterion for brain death [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. Owing to the complex anatomy of the brainstem, which contains multiple critical nuclei (Fig.\u0026nbsp;1), insults to this region can cause catastrophic sequelae, resulting in the loss of all brainstem reflexes. However, the brain cortex may still be viable, and the reticular activating system, located posterior to the pons, may remain uninjured, at least at the beginning of the injury, as evidenced by preserved electrical activity on EEG or VEP or preserved perfusion on CT angiography or brain scintigraphy. As such, this situation may pose a diagnostic dilemma since these patients fulfill the clinical criteria for brain death, but ancillary tests may reveal perfusion and electrical activity in the brain cortex, which argues against the definition of brain death. Herein, we present the clinical course, imaging, and outcome of a patient with basilar artery thrombosis, no brainstem reflexes, and preserved cortical brain perfusion on brain perfusion scintigraphy.\u003c/p\u003e"},{"header":"Case report","content":"\u003cp\u003eA 47-year-old woman was transported to the emergency department in an obtunded state after the sudden onset of right facial droop and aphasia. Her history was notable for 1 week of migraines and recent heavy loose tobacco use via pipe \"all day\". She had no history of seizures. In the emergency department, she had continuous seizures, quickly decompensated, and was intubated. Her natural institutional health stroke score (NIHSS) was at least 31. After the family was able to confirm that her last known normal was 3 hours prior, she received tPA and Keppra. A head CT revealed a dense basilar artery suggestive of thrombosis (Fig.\u0026nbsp;2). A head CTA was obtained and revealed distal basilar occlusion extending into the right P1 (Fig.\u0026nbsp;3). She underwent mechanical thrombectomy and was TICI 2B after 2 passes. The patient was then taken to the neuroICU after the procedure, and due to poor awakening from anesthesia, a head CT was obtained. Head CT revealed increased brainstem edema as well as obstructive hydrocephalus with decreased size of the 4th ventricle and increased sizes of the 3rd and lateral ventricles. Upon neurosurgical evaluation, she was not considered a good candidate for possible intervention because of a very poor neurologic exam and recent tPA administration. Follow-up head CT revealed evolving edema and infarction in the bilateral cerebellar hemispheres, brainstem, and right occipital lobe. The patient\u0026rsquo;s clinical condition continued to deteriorate. The patient clinically appeared to be \u0026lsquo;\u0026lsquo;brain dead\u0026rsquo;\u0026rsquo;, but no formal apnea test was ever performed. A confirmatory 99mTc bicisate brain blood flow study was performed (Fig.\u0026nbsp;4). Imaging was performed immediately and 20 minutes after the administration of 99mTc bicisate. Despite the complete absence of blood flow to the posterior fossa/cerebellum (arrows), there was diffuse uptake in both cerebral hemispheres. Medicolegally, the patient\u0026rsquo;s condition did not meet the definition of brain death; therefore, life support was continued. One-day follow-up brain CT revealed extensive cytotoxic edema involving the brainstem, bilateral cerebellar hemispheres, and occipital lobes as well as the development of upper transtentorial and descending tonsillar herniation and obstructive hydrocephalus. The same day, the patient was declared clinically brain dead with no follow-up images. The potential for organ donation was discussed with her family, who confirmed that this would respect the patient\u0026rsquo;s expressed wishes. Her kidneys and liver recovered successfully. Autopsy was not performed.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eAn isolated catastrophic brain stem lesion leading to \u0026ldquo;brain death\u0026rdquo; scenario is uncommon. From a series of 161 BD cases, Varela et al. reported three cases with isolated posterior fossa injury, accounting for a 1.9% prevalence among BD cases [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Isolated brainstem lesions can be observed in basilar artery thrombosis, such as in our case, subarachnoid hemorrhage, massive trauma, and complications of posterior fossa surgery [\u003cspan additionalcitationids=\"CR10\" citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. There are two other mechanisms that may impair posterior fossa function: first, large supratentorial lesions (e.g., ischemia, trauma, hemorrhage) with progressive transtentorial herniation and gradual loss of brainstem function. The second mechanism is diffuse brain parenchymal injury, such as hypoxia after cardiac arrest [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. Both of these mechanisms are associated with loss of function in both the supratentorial brain parenchyma and the brainstem, meeting the criteria for whole-brain death. Hence, in patients with fatal supratentorial lesions and in the absence of confounders, brain death can be reliably diagnosed on the basis of a thorough neurological examination. On the other hand, in patients with isolated catastrophic posterior fossa lesions, even though all brainstem reflexes are lost, the supratentorial brain is still viable. Furthermore, from an anatomical standpoint, the brainstem reflexes and the mesopontine tegmental reticular formation are located in different topographical regions, with the theoretical possibility of impaired brainstem reflexes while retaining reticular formation function\u0026mdash;a situation known as total locked-in syndrome [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. As such, diagnosing brain death in patients with fatal isolated posterior fossa lesions may be challenging because of the need for a thorough neurological examination. However, in our patient, the injury was extensive and involved the posterior midbrain.\u003c/p\u003e \u003cp\u003ePreserved supratentorial perfusion in the absence of infratentorial perfusion has been described in the literature in patients with catastrophic isolated posterior fossa lesions [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. It has also been described in a patient with fatal subarachnoid hemorrhage without isolated posterior fossa lesions [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. The significance of preserved supratentorial perfusion in the context of catastrophic brainstem damage is not clear. All these patients were ultimately declared brain dead within a few days, with or without further imaging. The inevitable supratentorial brain tissue injury can be explained by occlusion of the aqueduct secondary to brainstem edema, leading to progressive supratentorial hydrocephalus and gradual loss of supratentorial brain perfusion. Moreover, ongoing brain edema, resulting in the collapse of the vein of Galen, exacerbates this process, eventually leading to the inability of blood pressure to compensate for the disease. In accordance with prior case reports, our case showed the inevitability of the process, which eventually led to the declaration of brain death.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThe significance of preserved supratentorial brain perfusion in the context of isolated catastrophic posterior fossa lesions is not clear. In keeping with a few additional cases in the literature, preserved supratentorial perfusion in our patient quickly evolved. The complex brain stem anatomy warrants further ancillary tests for the confirmation of brain death in patients with isolated fatal posterior fossa lesions.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003eConsent to publish: The patient's next of kin (her adult daughter) was contacted by our clinic and provided consent for her mother's case to be reported in a medical journal.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eVarelas PN, Lewis A (2016) Modern Approach to Brain Death. Semin Neurol 36:625\u0026ndash;630. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1055/s-0036-1592317\u003c/span\u003e\u003cspan address=\"10.1055/s-0036-1592317\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRizvi T, Batchala P, Mukherjee S (2018) Brain Death: Diagnosis and Imaging Techniques. 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J Neurol Neurosurg Psychiatry 51:646\u0026ndash;650\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSchmidt MQ, Schraml FV (2017) Absent Cerebellar Circulation with Intact Cerebral Blood Flow on a 99mTc Bicisate Brain Death Study. Clin Nucl Med 42:983\u0026ndash;984. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1097/RLU.0000000000001866\u003c/span\u003e\u003cspan address=\"10.1097/RLU.0000000000001866\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eParvizi J, Damasio AR (2003) Neuroanatomical correlates of brainstem coma. Brain 126:1524\u0026ndash;1536. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1093/brain/awg166\u003c/span\u003e\u003cspan address=\"10.1093/brain/awg166\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eVarelas PN, Paul Brady P, Rehman M, Afshinnik A, Mehta C, Abdelhak T et al (2017) Primary Posterior Fossa Lesions and Preserved Supratentorial Cerebral Blood Flow: Implications for Brain Death Determination. Neurocrit Care 27:404\u0026ndash;407\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSchmidt MQ, Schraml FV (2017) Absent Cerebellar Circulation with Intact Cerebral Blood Flow on a 99mTc Bicisate Brain Death Study. Clin Nucl Med 42:983\u0026ndash;984. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1097/RLU.0000000000001866\u003c/span\u003e\u003cspan address=\"10.1097/RLU.0000000000001866\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"Washington University in St. Louis","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":"Brain death, Brainstem death, 99mTc bicisate brain blood flow study, basilar artery occlusion","lastPublishedDoi":"10.21203/rs.3.rs-4889425/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4889425/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cb\u003eBackground\u003c/b\u003e\u003c/p\u003e \u003cp\u003eThe brainstem anatomy is complex, and the diagnosis of brain death (BD) in patients with isolated catastrophic posterior fossa lesions may pose a diagnostic dilemma. This is because all brainstem reflexes (which are the basis of neurologic examination) are lost; however, from an anatomical standpoint, the mesopontine tegmental reticular formation (MPT-RF) can theoretically be intact in patients with brainstem death. Moreover, supratentorial perfusion and electrical activity may be present. The significance of preserved supratentorial perfusion in the context of isolated catastrophic brainstem damage is not clear. We report the outcomes of an adult patient with catastrophic basilar artery thrombosis with preserved cerebral perfusion on brain scintigraphy.\u003c/p\u003e\u003cp\u003e\u003cb\u003ePatient presentation:\u003c/b\u003e\u003c/p\u003e \u003cp\u003eA 47-year-old woman presented in an obtunded state and was found to have distal basilar artery thrombosis. After mechanical thrombectomy, her condition deteriorated, and a head CT scan revealed brain stem edema. Subsequently, brain death was suspected, and a 99mTc bicisate brain blood flow study was performed, which revealed the complete absence of blood flow to the cerebellum despite intact circulation to the cerebral hemispheres. Accordingly, life support continued. The next day, the patient was declared clinically brain dead with no follow-up imaging.\u003c/p\u003e\u003cp\u003e\u003cb\u003eConclusions\u003c/b\u003e\u003c/p\u003e \u003cp\u003eThe significance of preserved supratentorial brain perfusion in the context of isolated catastrophic posterior fossa lesions is unclear. In keeping with a few additional cases in the literature, preserved supratentorial perfusion in our patient quickly evolved. The complex brain stem anatomy warrants further ancillary tests for the confirmation of brain death in patients with isolated fatal posterior fossa lesions.\u003c/p\u003e","manuscriptTitle":"Isolated brain stem death: case report with demonstration of preserved cerebral perfusion in 99-TC biscicinate brain death study.","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-08-22 15:28:26","doi":"10.21203/rs.3.rs-4889425/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":"50f2e4d9-0807-469e-bf15-7aabda52cbf8","owner":[],"postedDate":"August 22nd, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":35850553,"name":"Nuclear Medicine \u0026 Medical Imaging"},{"id":35850554,"name":"Neurology"}],"tags":[],"updatedAt":"2024-08-22T15:28:26+00:00","versionOfRecord":[],"versionCreatedAt":"2024-08-22 15:28:26","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-4889425","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4889425","identity":"rs-4889425","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}