Incidental Detection of Pneumorrhachis in a Young Trauma Patient Following Combined Spinal–Epidural Anaesthesia: A Case Report and Literature Review

Incidental Detection of Pneumorrhachis in a Young Trauma Patient Following Combined Spinal–Epidural Anaesthesia: A Case Report and Literature Review | 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 Incidental Detection of Pneumorrhachis in a Young Trauma Patient Following Combined Spinal–Epidural Anaesthesia: A Case Report and Literature Review Pranati Yerramilli, Anand Kuppusamy, Venkata Padmavathi This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9206378/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 9 You are reading this latest preprint version Abstract Background Pneumorrhachis — the presence of gas within the spinal canal — is an uncommon radiological finding that most clinicians encounter only once or twice during a career. At one end of the spectrum, it resolves without a trace, and the patient never knows it was there; at the other, it signals neurological trouble that demands prompt attention. In patients who have sustained trauma and subsequently require neuraxial anaesthesia, the aetiology of intraspinal air is rarely straightforward, since both mechanisms can independently contribute. Case Report: A 19-year-old male presented following a road traffic accident with fractures of the left femoral shaft and multiple foot and hand bones. He was taken for open reduction and internal fixation under combined spinal–epidural anaesthesia. On the first postoperative day, he developed bilateral lower limb paraesthesia and left-sided motor weakness (3/5). Urgent CT of the dorsolumbar spine demonstrated epidural air at L2–L4 with paraspinal extension from L3 to S1. Subsequent MRI revealed paraspinal muscle oedema and an L4–L5 disc bulge indenting the thecal sac. The epidural catheter was removed, and high-flow oxygen with supportive analgesia was commenced. Neurological improvement was evident by the third postoperative day, and the patient was discharged on day 12 neurologically intact. Conclusion This case draws attention to pneumorrhachis as an underappreciated complication at the intersection of trauma and regional anaesthesia. Conservative management produced a complete recovery, but the diagnosis required a structured clinical and radiological approach. Anaesthesiologists working with multiply injured patients should maintain awareness of this entity, particularly when postoperative neurological signs do not follow an expected pattern. Pneumorrhachis Anesthesia Epidural Anesthesia Spinal Postoperative Complications Multiple Trauma Accidents Traffic Figures Figure 1 Figure 2 INTRODUCTION The spinal canal is ordinarily a closed, fluid-filled compartment in which the presence of gas is distinctly abnormal. When air is detected within this space — pneumorrhachis — clinicians face a narrow but diagnostically important differential. The reported incidence is difficult to quantify precisely because many cases are detected only on cross-sectional imaging obtained for other indications; the true frequency in trauma populations is therefore likely underestimated. [ 1 , 2 ] Aetiologically, pneumorrhachis is broadly divided into traumatic and non-traumatic subtypes. Traumatic cases most often arise from blunt thoracic injury, in which disrupted paraspinal tissues and elevated intrathoracic pressure create pathways for air to enter the spinal canal through the intervertebral foramina. [ 2 , 4 , 7 ] Non-traumatic causes include epidural and intrathecal air introduced during neuraxial procedures, infection with gas-forming organisms, and spontaneous pneumomediastinum dissecting along cervicothoracic fascial planes. [ 1 , 5 , 6 ] Anatomically, air may accumulate in the epidural space, within the subarachnoid space, or in both simultaneously, with the epidural variety generally regarded as carrying a more favourable prognosis. [ 3 , 5 ] The clinical spectrum is wide. Asymptomatic cases discovered on imaging represent one extreme; at the other end, neurological deficits can develop when sufficient air accumulates to exert a mass effect on neural structures. [ 3 , 5 ] Although most published accounts describe benign, self-limiting courses, clinicians must retain a low threshold for investigation because early detection directly influences management decisions. The following report describes an unusual clinical scenario in which pneumorrhachis arose in a young trauma patient who required neuraxial anaesthesia, creating diagnostic ambiguity about the primary source of intraspinal air. This case contributes to the small but growing body of literature on dual-mechanism pneumorrhachis and offers practical guidance for anaesthesiologists managing similar patients. CASE REPORT Patient background and initial assessment A 19-year-old male was brought to the emergency department following a road traffic accident. Injuries on primary survey included a closed fracture of the left femoral shaft, fractures of the 3rd through 5th left metatarsals, and fractures of the 1st and 2nd left metacarpals. There was no loss of consciousness, and on arrival, his Glasgow Coma Scale score was 15/15. Neurological examination of the lower limbs was normal. Haematological and biochemical investigations fell within reference ranges, and chest radiography showed no evidence of pneumothorax or pulmonary contusion. He was haemodynamically stable throughout the admission workup. Anaesthetic management The planned surgery was open reduction and internal fixation of the femoral fracture using an intramedullary interlocking nail, combined with wound debridement of the foot injury. A combined spinal–epidural technique was selected for anaesthesia: an epidural catheter was inserted at the L4–L5 interspace using a standard loss-of-resistance approach, followed by a subarachnoid block at L3–L4. The intraoperative course was entirely uneventful, with stable haemodynamics throughout and no technical difficulties during catheter placement. An epidural infusion of low-concentration local anaesthetic with opioid was commenced for postoperative pain control. Postoperative course On the first postoperative day (POD 1), the patient reported back pain and bilateral lower limb numbness. Although epidural infusion was promptly discontinued, the paraesthesia persisted and was accompanied by demonstrable left lower limb weakness, with motor power graded at 3/5 on the Medical Research Council scale. The neurological picture was inconsistent with a residual local anaesthetic block, both in its distribution and in its failure to resolve after cessation of infusion. Heparin thromboprophylaxis was withheld, the epidural catheter was removed, and urgent CT of the dorsolumbar spine was requested. CT imaging demonstrated epidural air at the L2–L3 and L4 levels with paraspinal gas collections extending from L3 to S1. No haematoma or abscess was identified. High-flow oxygen therapy was commenced alongside analgesic support. Figures 1 and 2 . On POD 2, a neurology consultation was obtained. MRI of the lumbar spine was performed and revealed paraspinal muscle oedema at multiple levels, along with a disc bulge at L4–L5 with mild indentation of the thecal sac. No signal change within the cord was noted. Serial neurological assessments were continued. By POD 3–4, the patient's lower limb strength had recovered to 4/5 bilaterally, and the paraesthesia was diminishing. On POD 6, he underwent further fixation of the hand and foot fractures under general anaesthesia, which was uneventful. He was discharged on POD 12 with full neurological recovery and no residual sensory or motor deficits. No further imaging was deemed necessary at discharge, given his complete clinical resolution. DISCUSSION The case presented here sits at a clinically awkward intersection: a young patient whose spinal canal air could plausibly have originated from trauma, from the neuraxial procedure, or from some combination of both. Unravelling this question has implications not just for understanding what happened in this individual, but for how similar cases should be approached prospectively. Pneumorrhachis following blunt trauma is most commonly linked to thoracic cage injuries in which rib fractures, pulmonary lacerations, or pneumothorax generate positive pressure gradients that push air centripetally through the intervertebral foramina into the epidural space. [ 2 , 4 ] Goh and Yeo, in their review of traumatic pneumorrhachis, consistently identified thoracic pathology as the anatomical conduit through which air reached the spinal canal. [ 2 ] Newbold and colleagues drew attention to the radiological pattern of paraspinal air tracking inward from the site of thoracic injury, reinforcing the pressure-gradient hypothesis. [ 4 ] Akay and Bayram further emphasised that this mechanism tends to operate rapidly after injury, often resulting in air visible on the initial trauma CT. [ 7 ] In our patient, the absence of chest trauma, rib fractures, or pleural pathology substantially weakens the case for a purely traumatic aetiology. The peripheral fractures sustained — femoral shaft, metatarsals, metacarpals — do not generate the intrathoracic pressure changes required for the classical foraminal entry mechanism. This absence redirects clinical suspicion toward the epidural procedure as the dominant source. Air introduced during loss-of-resistance testing or through micro-injections during catheter advancement can accumulate in the epidural space and, under certain circumstances, migrate to adjacent levels or into the paraspinal soft tissues. [ 1 , 6 ] Shaikh and colleagues described this pattern precisely following epidural analgesia, with air disseminating beyond the immediate injection site to produce both pneumorrhachis and pneumothorax. [ 1 ] Fountoulaki et al. reported an even more dramatic case in which epidural air caused pneumomediastinum with haemodynamic instability, demonstrating that the anatomical spread of injected air is not reliably predictable. [ 6 ] A further consideration is that the periosteal and paraspinal disruption from the original trauma may have altered the normal tissue barriers around the lumbar spine, potentially facilitating wider distribution of epidural air than would occur in an anatomically intact patient. The combination of a mechanically disrupted tissue environment and an exogenous air source may therefore be synergistic in a way that neither mechanism alone would produce. The predominant clinical finding in published cases of pneumorrhachis is no finding at all — the condition is asymptomatic in the majority, surfacing only because imaging was obtained for another reason. [ 2 , 5 ] When symptoms do manifest, back pain and sensory disturbance are the most frequent, with frank motor deficits representing a smaller subset. [ 3 , 7 ] Kim and Seo, reporting a case of symptomatic epidural pneumorrhachis with objective neurological signs, noted that even patients with demonstrable motor weakness typically recover fully with conservative management and that the initial severity of the deficit does not reliably predict the ultimate outcome. [ 3 ] This observation was borne out in our patient, who presented with 3/5 power but achieved full recovery without surgical intervention. What made diagnosis here more demanding than a straightforward pneumorrhachis was the concurrent MRI finding of an L4–L5 disc bulge with thecal sac indentation. The symptoms began on POD 1 in close association with the CT-confirmed air, and they improved in parallel with the expected reabsorption timeline for epidural gas rather than following the fluctuating or persistent course more typical of disc-mediated radiculopathy. The disc finding was therefore interpreted as an incidental or contributory element rather than the primary driver of the deficit. CT of the lumbar spine remains the investigation of choice when pneumorrhachis is suspected, offering high sensitivity even for small gas volumes and enabling precise localisation within the epidural or intradural compartments. [ 2 , 5 ] MRI, while less sensitive for air itself, provides important information about associated soft tissue pathology, disc disease, and critically, whether the spinal cord shows signal changes suggesting contusion or ischaemia. [ 3 , 5 ] In any patient where the neurological examination raises concern beyond what the CT air distribution alone would explain, MRI should follow without delay. Oertel and colleagues, in their analysis of pneumorrhachis management, proposed that the CT extent of air and the neurological examination together constitute the two most clinically actionable parameters when deciding between conservative and surgical pathways. [ 5 ] Conservative management has emerged as the default strategy for pneumorrhachis across both traumatic and procedural aetiologies, supported by the consistent observation that intraspinal air reabsorbs spontaneously in most cases without lasting neurological consequence. [ 1 , 3 , 5 ] High-flow oxygen is the pharmacological cornerstone of this approach: by flooding the alveoli and lowering the partial pressure of nitrogen in the blood, it establishes a diffusion gradient that draws nitrogen out of the epidural space and into the circulation, resulting in resolution compared with breathing ambient air. [ 5 ] Analgesic support addresses the back pain that accompanies most symptomatic cases. Removal of the epidural catheter was undertaken early in this case and represents sound practice when the catheter is a plausible source of ongoing air introduction. Retaining an epidural catheter in situ while intraspinal air is accumulating and producing neurological signs would be difficult to justify, regardless of its analgesic utility. The indications for surgical decompression remain narrow and are confined to patients in whom motor deficits are rapidly progressive, fail to stabilise, or continue to worsen despite conservative measures. [ 3 , 5 ] None of these criteria were met in our patient, whose trajectory was one of steady improvement from the outset. The multidisciplinary approach — involving anaesthesiology, neurology, and the surgical team — facilitated structured decision-making and prevented premature escalation to invasive management. The single most modifiable risk factor for iatrogenic pneumorrhachis during epidural anaesthesia is the choice of loss-of-resistance medium. Air-based techniques carry an inherent risk of introducing variable volumes of gas into the epidural space; saline eliminates this risk entirely while maintaining equivalent reliability for identifying the epidural space. [ 1 , 6 ] The existing literature, including the cases of Shaikh et al. [ 1 ] and Fountoulaki et al. [6] consistently support saline as the preferred medium, and this recommendation is particularly compelling in patients with disrupted paraspinal anatomy from prior trauma. Beyond technique, this case illustrates the value of a structured postoperative neurological assessment protocol following neuraxial procedures in trauma patients. Lower limb symptoms that fail to resolve within the expected timeframe after cessation of epidural infusion, or that appear in a distribution inconsistent with the block level, should prompt early cross-sectional imaging rather than a period of watchful waiting. The differential in this context includes epidural haematoma, abscess, and pneumorrhachis, all of which require imaging to distinguish and carry different management implications. CONCLUSION Pneumorrhachis occupies a tiny but instructive corner of the spinal pathology literature. This case adds to the evidence that the condition can arise through overlapping mechanisms, in this instance, a traumatic background combined with an epidural procedure in a young patient, and that it may produce neurological deficits that, while alarming on presentation, resolve fully with conservative care. For anaesthesiologists, the practical takeaways are straightforward: saline-based loss-of-resistance reduces procedural risk; unexplained postoperative neurological signs in a trauma patient warrant prompt CT imaging; and most patients with confirmed pneumorrhachis, even those with motor deficits, can be managed without surgical intervention provided the clinical course is monitored carefully. The self-limiting nature of this condition should not, however, be taken lightly, as the capacity to deteriorate exists, and the threshold for escalation must remain clearly defined before it is needed. Declarations Ethics approval: Not applicable Consent for publication: The authors certify that they have obtained all appropriate patient consent forms. The patient has provided written consent for his clinical information and images to be reported in the journal. His name and initials will not be published, and all reasonable efforts have been made to conceal his identity, though complete anonymity cannot be guaranteed. Availability of data and materials: Not applicable Competing interests: The authors declare no competing interests. Funding: Nil. Authors’ contributions: All authors contributed equally to case management, data collection, and manuscript preparation. Acknowlegments: Not applicable References Shaikh N, Nawaz S, Mathias R, Ma R, Lance M, Ummunissa F, Khalifa Tellisi A. Pneumorrhachis and pneumothorax after epidural analgesia: a case report and review. Qatar Med J. 2020;2021(1):1. Goh BK, Yeo AW. Traumatic pneumorrhachis. J Trauma Acute Care Surg. 2005;58(4):875–9. Kim SW, Seo HJ. Symptomatic epidural pneumorrhachis: a rare entity. J Korean Neurosurg Soc. 2013;54(1):65–7. Newbold RG, Wiener MD, Vogler JB 3rd, Martinez S. Traumatic pneumorrhachis. AJR Am J Roentgenol. 1987;148(3):615–6. Oertel MF, Korinth MC, Reinges MH, Krings T, Terbeck S, Gilsbach JM. Pathogenesis, diagnosis and management of pneumorrhachis. Eur Spine J. 2006;15(Suppl 5):636–43. Fountoulaki M, Kapetanakis EI, Kouna N, Papagiannis N, Sidiropoulou T. Hemodynamic instability caused by pneumorrachis and pneumomediastinum following epidural analgesia: a case report. J Med Case Rep. 2024;18(1):263. Akay S, Bayram B. Traumatic pneumorrhachis: a rare entity of trauma. Int J Emerg Med. 2008;1(1):53. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Reviews received at journal 09 May, 2026 Reviews received at journal 03 May, 2026 Reviewers agreed at journal 27 Apr, 2026 Reviewers agreed at journal 22 Apr, 2026 Reviewers invited by journal 21 Apr, 2026 Editor invited by journal 27 Mar, 2026 Editor assigned by journal 25 Mar, 2026 Submission checks completed at journal 25 Mar, 2026 First submitted to journal 23 Mar, 2026 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. We do this by developing innovative software and high quality services for the global research community. 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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-9206378","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Case Report","associatedPublications":[],"authors":[{"id":630967608,"identity":"eadb487d-2a55-4cb4-84ea-90eff7a1ec51","order_by":0,"name":"Pranati Yerramilli","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA6ElEQVRIiWNgGAWjYFAC/ucfPv6zATIYGxggJISBB/CwMc5gS4MoPkCsFmYetsMQ9gEGwuoZzCVyjz3m4Tlvbz7tcPPnDww2shsOMLc9wKfFckZeuuEciduJc24ntkkcYEgz3nCAsd0AnxaDGwkGEm8MbidISCe2AR12OBGopU2CoBaehHP2QC3NHw4w/CdGS46ZJM+BA4wzpBMbgA47QFiLZc+zZMOZDcmJQC1tEmcMko1nHiagxZw9+eCDjw12QIelP/5QUWEn23e8/Rl+hwkkoHCBmBmfepAa/gMEVIyCUTAKRsEoAACexlDZb9jVGAAAAABJRU5ErkJggg==","orcid":"","institution":"SRM Institute of Science and Technology","correspondingAuthor":true,"prefix":"","firstName":"Pranati","middleName":"","lastName":"Yerramilli","suffix":""},{"id":630967609,"identity":"ccb033ce-cd34-4884-8aab-297f96ba0004","order_by":1,"name":"Anand Kuppusamy","email":"","orcid":"","institution":"SRM Institute of Science and Technology","correspondingAuthor":false,"prefix":"","firstName":"Anand","middleName":"","lastName":"Kuppusamy","suffix":""},{"id":630967610,"identity":"275629dc-b38b-40f9-ae7a-d52c42acdf4b","order_by":2,"name":"Venkata Padmavathi","email":"","orcid":"","institution":"SRM Institute of Science and Technology","correspondingAuthor":false,"prefix":"","firstName":"Venkata","middleName":"","lastName":"Padmavathi","suffix":""}],"badges":[],"createdAt":"2026-03-24 03:53:56","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9206378/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9206378/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":108389416,"identity":"00a33b4b-c62e-42e7-bdda-dd125e8566e7","added_by":"auto","created_at":"2026-05-04 06:49:29","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":20116,"visible":true,"origin":"","legend":"\u003cp\u003eCT scan of the patient showing air in the epidural space\u003c/p\u003e","description":"","filename":"Figure1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-9206378/v1/a08afa6a840cda021f974ce1.jpg"},{"id":108389417,"identity":"dbf334a8-2cfe-4b7d-a263-584c9f9c13ae","added_by":"auto","created_at":"2026-05-04 06:49:29","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":20210,"visible":true,"origin":"","legend":"\u003cp\u003eCT scan of the patient showing air in the epidural space\u003c/p\u003e","description":"","filename":"Figure2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-9206378/v1/c0772ecc0267b3ccf6d1e5e2.jpg"},{"id":108493494,"identity":"512947c1-15fb-4860-99ef-679bc3d79d03","added_by":"auto","created_at":"2026-05-05 10:00:42","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":192310,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9206378/v1/43557170-1bd2-446b-9dce-f6ed0dcfaa30.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Incidental Detection of Pneumorrhachis in a Young Trauma Patient Following Combined Spinal–Epidural Anaesthesia: A Case Report and Literature Review","fulltext":[{"header":"INTRODUCTION","content":"\u003cp\u003eThe spinal canal is ordinarily a closed, fluid-filled compartment in which the presence of gas is distinctly abnormal. When air is detected within this space \u0026mdash; pneumorrhachis \u0026mdash; clinicians face a narrow but diagnostically important differential. The reported incidence is difficult to quantify precisely because many cases are detected only on cross-sectional imaging obtained for other indications; the true frequency in trauma populations is therefore likely underestimated.\u003csup\u003e[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eAetiologically, pneumorrhachis is broadly divided into traumatic and non-traumatic subtypes. Traumatic cases most often arise from blunt thoracic injury, in which disrupted paraspinal tissues and elevated intrathoracic pressure create pathways for air to enter the spinal canal through the intervertebral foramina.\u003csup\u003e[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]\u003c/sup\u003e Non-traumatic causes include epidural and intrathecal air introduced during neuraxial procedures, infection with gas-forming organisms, and spontaneous pneumomediastinum dissecting along cervicothoracic fascial planes.\u003csup\u003e[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]\u003c/sup\u003e Anatomically, air may accumulate in the epidural space, within the subarachnoid space, or in both simultaneously, with the epidural variety generally regarded as carrying a more favourable prognosis.\u003csup\u003e[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eThe clinical spectrum is wide. Asymptomatic cases discovered on imaging represent one extreme; at the other end, neurological deficits can develop when sufficient air accumulates to exert a mass effect on neural structures.\u003csup\u003e[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]\u003c/sup\u003e Although most published accounts describe benign, self-limiting courses, clinicians must retain a low threshold for investigation because early detection directly influences management decisions. The following report describes an unusual clinical scenario in which pneumorrhachis arose in a young trauma patient who required neuraxial anaesthesia, creating diagnostic ambiguity about the primary source of intraspinal air. This case contributes to the small but growing body of literature on dual-mechanism pneumorrhachis and offers practical guidance for anaesthesiologists managing similar patients.\u003c/p\u003e"},{"header":"CASE REPORT","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003ePatient background and initial assessment\u003c/h2\u003e \u003cp\u003eA 19-year-old male was brought to the emergency department following a road traffic accident. Injuries on primary survey included a closed fracture of the left femoral shaft, fractures of the 3rd through 5th left metatarsals, and fractures of the 1st and 2nd left metacarpals. There was no loss of consciousness, and on arrival, his Glasgow Coma Scale score was 15/15. Neurological examination of the lower limbs was normal. Haematological and biochemical investigations fell within reference ranges, and chest radiography showed no evidence of pneumothorax or pulmonary contusion. He was haemodynamically stable throughout the admission workup.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eAnaesthetic management\u003c/h3\u003e\n\u003cp\u003eThe planned surgery was open reduction and internal fixation of the femoral fracture using an intramedullary interlocking nail, combined with wound debridement of the foot injury. A combined spinal\u0026ndash;epidural technique was selected for anaesthesia: an epidural catheter was inserted at the L4\u0026ndash;L5 interspace using a standard loss-of-resistance approach, followed by a subarachnoid block at L3\u0026ndash;L4. The intraoperative course was entirely uneventful, with stable haemodynamics throughout and no technical difficulties during catheter placement. An epidural infusion of low-concentration local anaesthetic with opioid was commenced for postoperative pain control.\u003c/p\u003e\n\u003ch3\u003ePostoperative course\u003c/h3\u003e\n\u003cp\u003eOn the first postoperative day (POD 1), the patient reported back pain and bilateral lower limb numbness. Although epidural infusion was promptly discontinued, the paraesthesia persisted and was accompanied by demonstrable left lower limb weakness, with motor power graded at 3/5 on the Medical Research Council scale. The neurological picture was inconsistent with a residual local anaesthetic block, both in its distribution and in its failure to resolve after cessation of infusion. Heparin thromboprophylaxis was withheld, the epidural catheter was removed, and urgent CT of the dorsolumbar spine was requested.\u003c/p\u003e \u003cp\u003eCT imaging demonstrated epidural air at the L2\u0026ndash;L3 and L4 levels with paraspinal gas collections extending from L3 to S1. No haematoma or abscess was identified. High-flow oxygen therapy was commenced alongside analgesic support. Figures\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e and \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eOn POD 2, a neurology consultation was obtained. MRI of the lumbar spine was performed and revealed paraspinal muscle oedema at multiple levels, along with a disc bulge at L4\u0026ndash;L5 with mild indentation of the thecal sac. No signal change within the cord was noted. Serial neurological assessments were continued.\u003c/p\u003e \u003cp\u003eBy POD 3\u0026ndash;4, the patient's lower limb strength had recovered to 4/5 bilaterally, and the paraesthesia was diminishing. On POD 6, he underwent further fixation of the hand and foot fractures under general anaesthesia, which was uneventful. He was discharged on POD 12 with full neurological recovery and no residual sensory or motor deficits. No further imaging was deemed necessary at discharge, given his complete clinical resolution.\u003c/p\u003e"},{"header":"DISCUSSION","content":"\u003cp\u003eThe case presented here sits at a clinically awkward intersection: a young patient whose spinal canal air could plausibly have originated from trauma, from the neuraxial procedure, or from some combination of both. Unravelling this question has implications not just for understanding what happened in this individual, but for how similar cases should be approached prospectively.\u003c/p\u003e \u003cp\u003ePneumorrhachis following blunt trauma is most commonly linked to thoracic cage injuries in which rib fractures, pulmonary lacerations, or pneumothorax generate positive pressure gradients that push air centripetally through the intervertebral foramina into the epidural space.\u003csup\u003e[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]\u003c/sup\u003e Goh and Yeo, in their review of traumatic pneumorrhachis, consistently identified thoracic pathology as the anatomical conduit through which air reached the spinal canal.\u003csup\u003e[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]\u003c/sup\u003e Newbold and colleagues drew attention to the radiological pattern of paraspinal air tracking inward from the site of thoracic injury, reinforcing the pressure-gradient hypothesis.\u003csup\u003e[\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]\u003c/sup\u003e Akay and Bayram further emphasised that this mechanism tends to operate rapidly after injury, often resulting in air visible on the initial trauma CT.\u003csup\u003e[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eIn our patient, the absence of chest trauma, rib fractures, or pleural pathology substantially weakens the case for a purely traumatic aetiology. The peripheral fractures sustained \u0026mdash; femoral shaft, metatarsals, metacarpals \u0026mdash; do not generate the intrathoracic pressure changes required for the classical foraminal entry mechanism. This absence redirects clinical suspicion toward the epidural procedure as the dominant source. Air introduced during loss-of-resistance testing or through micro-injections during catheter advancement can accumulate in the epidural space and, under certain circumstances, migrate to adjacent levels or into the paraspinal soft tissues.\u003csup\u003e[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]\u003c/sup\u003e Shaikh and colleagues described this pattern precisely following epidural analgesia, with air disseminating beyond the immediate injection site to produce both pneumorrhachis and pneumothorax.\u003csup\u003e[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]\u003c/sup\u003e Fountoulaki et al. reported an even more dramatic case in which epidural air caused pneumomediastinum with haemodynamic instability, demonstrating that the anatomical spread of injected air is not reliably predictable.\u003csup\u003e[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eA further consideration is that the periosteal and paraspinal disruption from the original trauma may have altered the normal tissue barriers around the lumbar spine, potentially facilitating wider distribution of epidural air than would occur in an anatomically intact patient. The combination of a mechanically disrupted tissue environment and an exogenous air source may therefore be synergistic in a way that neither mechanism alone would produce.\u003c/p\u003e \u003cp\u003eThe predominant clinical finding in published cases of pneumorrhachis is no finding at all \u0026mdash; the condition is asymptomatic in the majority, surfacing only because imaging was obtained for another reason.\u003csup\u003e[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]\u003c/sup\u003e When symptoms do manifest, back pain and sensory disturbance are the most frequent, with frank motor deficits representing a smaller subset.\u003csup\u003e[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]\u003c/sup\u003e Kim and Seo, reporting a case of symptomatic epidural pneumorrhachis with objective neurological signs, noted that even patients with demonstrable motor weakness typically recover fully with conservative management and that the initial severity of the deficit does not reliably predict the ultimate outcome.\u003csup\u003e[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]\u003c/sup\u003e This observation was borne out in our patient, who presented with 3/5 power but achieved full recovery without surgical intervention.\u003c/p\u003e \u003cp\u003eWhat made diagnosis here more demanding than a straightforward pneumorrhachis was the concurrent MRI finding of an L4\u0026ndash;L5 disc bulge with thecal sac indentation. The symptoms began on POD 1 in close association with the CT-confirmed air, and they improved in parallel with the expected reabsorption timeline for epidural gas rather than following the fluctuating or persistent course more typical of disc-mediated radiculopathy. The disc finding was therefore interpreted as an incidental or contributory element rather than the primary driver of the deficit.\u003c/p\u003e \u003cp\u003eCT of the lumbar spine remains the investigation of choice when pneumorrhachis is suspected, offering high sensitivity even for small gas volumes and enabling precise localisation within the epidural or intradural compartments.\u003csup\u003e[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]\u003c/sup\u003e MRI, while less sensitive for air itself, provides important information about associated soft tissue pathology, disc disease, and critically, whether the spinal cord shows signal changes suggesting contusion or ischaemia.\u003csup\u003e[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]\u003c/sup\u003e In any patient where the neurological examination raises concern beyond what the CT air distribution alone would explain, MRI should follow without delay. Oertel and colleagues, in their analysis of pneumorrhachis management, proposed that the CT extent of air and the neurological examination together constitute the two most clinically actionable parameters when deciding between conservative and surgical pathways.\u003csup\u003e[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eConservative management has emerged as the default strategy for pneumorrhachis across both traumatic and procedural aetiologies, supported by the consistent observation that intraspinal air reabsorbs spontaneously in most cases without lasting neurological consequence.\u003csup\u003e[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]\u003c/sup\u003e High-flow oxygen is the pharmacological cornerstone of this approach: by flooding the alveoli and lowering the partial pressure of nitrogen in the blood, it establishes a diffusion gradient that draws nitrogen out of the epidural space and into the circulation, resulting in resolution compared with breathing ambient air.\u003csup\u003e[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]\u003c/sup\u003e Analgesic support addresses the back pain that accompanies most symptomatic cases.\u003c/p\u003e \u003cp\u003eRemoval of the epidural catheter was undertaken early in this case and represents sound practice when the catheter is a plausible source of ongoing air introduction. Retaining an epidural catheter in situ while intraspinal air is accumulating and producing neurological signs would be difficult to justify, regardless of its analgesic utility.\u003c/p\u003e \u003cp\u003eThe indications for surgical decompression remain narrow and are confined to patients in whom motor deficits are rapidly progressive, fail to stabilise, or continue to worsen despite conservative measures.\u003csup\u003e[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]\u003c/sup\u003e None of these criteria were met in our patient, whose trajectory was one of steady improvement from the outset. The multidisciplinary approach \u0026mdash; involving anaesthesiology, neurology, and the surgical team \u0026mdash; facilitated structured decision-making and prevented premature escalation to invasive management.\u003c/p\u003e \u003cp\u003eThe single most modifiable risk factor for iatrogenic pneumorrhachis during epidural anaesthesia is the choice of loss-of-resistance medium. Air-based techniques carry an inherent risk of introducing variable volumes of gas into the epidural space; saline eliminates this risk entirely while maintaining equivalent reliability for identifying the epidural space.\u003csup\u003e[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]\u003c/sup\u003e The existing literature, including the cases of Shaikh et al.\u003csup\u003e[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]\u003c/sup\u003e and Fountoulaki et al. [6] consistently support saline as the preferred medium, and this recommendation is particularly compelling in patients with disrupted paraspinal anatomy from prior trauma.\u003c/p\u003e \u003cp\u003eBeyond technique, this case illustrates the value of a structured postoperative neurological assessment protocol following neuraxial procedures in trauma patients. Lower limb symptoms that fail to resolve within the expected timeframe after cessation of epidural infusion, or that appear in a distribution inconsistent with the block level, should prompt early cross-sectional imaging rather than a period of watchful waiting. The differential in this context includes epidural haematoma, abscess, and pneumorrhachis, all of which require imaging to distinguish and carry different management implications.\u003c/p\u003e"},{"header":"CONCLUSION","content":"\u003cp\u003ePneumorrhachis occupies a tiny but instructive corner of the spinal pathology literature. This case adds to the evidence that the condition can arise through overlapping mechanisms, in this instance, a traumatic background combined with an epidural procedure in a young patient, and that it may produce neurological deficits that, while alarming on presentation, resolve fully with conservative care. For anaesthesiologists, the practical takeaways are straightforward: saline-based loss-of-resistance reduces procedural risk; unexplained postoperative neurological signs in a trauma patient warrant prompt CT imaging; and most patients with confirmed pneumorrhachis, even those with motor deficits, can be managed without surgical intervention provided the clinical course is monitored carefully. The self-limiting nature of this condition should not, however, be taken lightly, as the capacity to deteriorate exists, and the threshold for escalation must remain clearly defined before it is needed.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval:\u0026nbsp;\u003c/strong\u003eNot applicable\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication:\u0026nbsp;\u003c/strong\u003eThe authors certify that they have obtained all appropriate patient consent forms. The patient has provided written consent for his clinical information and images to be reported in the journal. His name and initials will not be published, and all reasonable efforts have been made to conceal his identity, though complete anonymity cannot be guaranteed.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials:\u0026nbsp;\u003c/strong\u003eNot applicable\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests:\u0026nbsp;\u003c/strong\u003eThe authors declare no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding:\u0026nbsp;\u003c/strong\u003eNil.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026rsquo; contributions:\u0026nbsp;\u003c/strong\u003eAll authors contributed equally to case management, data collection, and manuscript preparation.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowlegments:\u0026nbsp;\u003c/strong\u003eNot applicable\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eShaikh N, Nawaz S, Mathias R, Ma R, Lance M, Ummunissa F, Khalifa Tellisi A. Pneumorrhachis and pneumothorax after epidural analgesia: a case report and review. Qatar Med J. 2020;2021(1):1.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGoh BK, Yeo AW. Traumatic pneumorrhachis. J Trauma Acute Care Surg. 2005;58(4):875\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKim SW, Seo HJ. Symptomatic epidural pneumorrhachis: a rare entity. J Korean Neurosurg Soc. 2013;54(1):65\u0026ndash;7.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNewbold RG, Wiener MD, Vogler JB 3rd, Martinez S. Traumatic pneumorrhachis. AJR Am J Roentgenol. 1987;148(3):615\u0026ndash;6.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eOertel MF, Korinth MC, Reinges MH, Krings T, Terbeck S, Gilsbach JM. Pathogenesis, diagnosis and management of pneumorrhachis. Eur Spine J. 2006;15(Suppl 5):636\u0026ndash;43.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFountoulaki M, Kapetanakis EI, Kouna N, Papagiannis N, Sidiropoulou T. Hemodynamic instability caused by pneumorrachis and pneumomediastinum following epidural analgesia: a case report. J Med Case Rep. 2024;18(1):263.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAkay S, Bayram B. Traumatic pneumorrhachis: a rare entity of trauma. Int J Emerg Med. 2008;1(1):53.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"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":"bmc-anesthesiology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bane","sideBox":"Learn more about [BMC Anesthesiology](http://bmcanesthesiol.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/bane","title":"BMC Anesthesiology","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Pneumorrhachis, Anesthesia, Epidural, Anesthesia, Spinal, Postoperative Complications, Multiple Trauma, Accidents, Traffic","lastPublishedDoi":"10.21203/rs.3.rs-9206378/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9206378/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e \u003cp\u003ePneumorrhachis \u0026mdash; the presence of gas within the spinal canal \u0026mdash; is an uncommon radiological finding that most clinicians encounter only once or twice during a career. At one end of the spectrum, it resolves without a trace, and the patient never knows it was there; at the other, it signals neurological trouble that demands prompt attention. In patients who have sustained trauma and subsequently require neuraxial anaesthesia, the aetiology of intraspinal air is rarely straightforward, since both mechanisms can independently contribute.\u003c/p\u003e\u003ch2\u003eCase Report:\u003c/h2\u003e \u003cp\u003eA 19-year-old male presented following a road traffic accident with fractures of the left femoral shaft and multiple foot and hand bones. He was taken for open reduction and internal fixation under combined spinal\u0026ndash;epidural anaesthesia. On the first postoperative day, he developed bilateral lower limb paraesthesia and left-sided motor weakness (3/5). Urgent CT of the dorsolumbar spine demonstrated epidural air at L2\u0026ndash;L4 with paraspinal extension from L3 to S1. Subsequent MRI revealed paraspinal muscle oedema and an L4\u0026ndash;L5 disc bulge indenting the thecal sac. The epidural catheter was removed, and high-flow oxygen with supportive analgesia was commenced. Neurological improvement was evident by the third postoperative day, and the patient was discharged on day 12 neurologically intact.\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e \u003cp\u003eThis case draws attention to pneumorrhachis as an underappreciated complication at the intersection of trauma and regional anaesthesia. Conservative management produced a complete recovery, but the diagnosis required a structured clinical and radiological approach. Anaesthesiologists working with multiply injured patients should maintain awareness of this entity, particularly when postoperative neurological signs do not follow an expected pattern.\u003c/p\u003e","manuscriptTitle":"Incidental Detection of Pneumorrhachis in a Young Trauma Patient Following Combined Spinal–Epidural Anaesthesia: A Case Report and Literature Review","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-05-04 06:49:25","doi":"10.21203/rs.3.rs-9206378/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"editorInvitedReview","content":"","date":"2026-05-09T14:36:58+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-05-03T12:41:24+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"62663184661679493930740821350118533433","date":"2026-04-27T12:49:50+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"299673987010650823917855245156647972830","date":"2026-04-22T08:53:19+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-04-21T13:36:27+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2026-03-27T11:13:45+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-03-25T05:41:43+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-03-25T05:40:55+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Anesthesiology","date":"2026-03-24T03:36:33+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-anesthesiology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bane","sideBox":"Learn more about [BMC Anesthesiology](http://bmcanesthesiol.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/bane","title":"BMC Anesthesiology","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"f876f57f-ee02-41e5-a907-ad47e2baeebc","owner":[],"postedDate":"May 4th, 2026","published":true,"recentEditorialEvents":[{"type":"editorInvitedReview","content":"","date":"2026-05-09T14:36:58+00:00","index":57,"fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-05-03T12:41:24+00:00","index":56,"fulltext":""}],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-05-04T06:49:26+00:00","versionOfRecord":[],"versionCreatedAt":"2026-05-04 06:49:25","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9206378","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9206378","identity":"rs-9206378","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}