{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,29]],"date-time":"2026-01-29T22:31:39Z","timestamp":1769725899501,"version":"3.49.0"},"reference-count":18,"publisher":"Journal of Neurosurgery Publishing Group (JNSPG)","issue":"14","license":[{"start":{"date-parts":[[2025,10,6]],"date-time":"2025-10-06T00:00:00Z","timestamp":1759708800000},"content-version":"unspecified","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by-nc-nd\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["J Neurosurg Case Lessons"],"published-print":{"date-parts":[[2025,10,6]]},"abstract":"<jats:sec>\n                    <jats:title>BACKGROUND<\/jats:title>\n                    <jats:p>Chiari malformation type I (CM-I) is characterized by the descent of the cerebellar tonsils through the foramen magnum. In some patients, this condition can be acquired secondarily due to another condition that alters the dynamics of CSF in the foramen magnum, leading to tonsillar herniation. In this report, the authors describe a case of an acquired CM-I occurring 3 years after a traumatic atlanto-occipital dislocation (AOD).<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>OBSERVATIONS<\/jats:title>\n                    <jats:p>The authors report the case of a 31-year-old male who initially presented with traumatic AOD associated with a craniocervical hematoma and subsequently developed CM-I. MRI revealed herniation of the cerebellar tonsils through the foramen magnum and extensive cervical spinal cord hyperintensity indicative of a presyrinx state. The patient underwent a suboccipital craniectomy, partial laminectomies of C1 and C2, and duraplasty. After surgery, he exhibited progressive improvement, achieving complete neurological recovery. Postoperative MRI demonstrated complete resolution of the cerebellar descent and the signal changes in the cord.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>LESSONS<\/jats:title>\n                    <jats:p>The authors describe the case of a patient presenting with CM-I after experiencing an AOD and a circumferential hematoma in the cervicomedullary junction. Although rare, clinicians should consider CM-I in the differential diagnosis of patients who present with delayed neurological symptoms after sustaining traumatic injury to the craniovertebral region.<\/jats:p>\n                    <jats:p>\n                      <jats:ext-link xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" ext-link-type=\"uri\" xlink:href=\"https:\/\/thejns.org\/doi\/10.3171\/CASE25473\">https:\/\/thejns.org\/doi\/10.3171\/CASE25473<\/jats:ext-link>\n                    <\/jats:p>\n                  <\/jats:sec>","DOI":"10.3171\/case25473","type":"journal-article","created":{"date-parts":[[2025,10,7]],"date-time":"2025-10-07T00:01:37Z","timestamp":1759795297000},"source":"Crossref","is-referenced-by-count":0,"title":["Acquired Chiari malformation type I after atlanto-occipital dislocation: illustrative case"],"prefix":"10.3171","volume":"10","author":[{"given":"Luis A.","family":"Robles","sequence":"first","affiliation":[{"name":"Department of Neurosurgery, University of Arizona College of Medicine, Tucson, Arizona"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0009-0007-0010-8061","authenticated-orcid":true,"given":"Ibrahim","family":"Alhalal","sequence":"additional","affiliation":[{"name":"Department of Neurosurgery, University of Arizona College of Medicine, Tucson, Arizona"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"R. John","family":"Hurlbert","sequence":"additional","affiliation":[{"name":"Department of Neurosurgery, University of Arizona College of Medicine, Tucson, Arizona"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1754","reference":[{"issue":"5","key":"bib1","series-title":"Neurosurgery","first-page":"1005","article-title":"Chiari I malformation redefined: clinical and radiographic findings for 364 symptomatic patients","volume":"44","author":"Milhorat","year":"1999","unstructured":"Milhorat THChou MWTrinidad EMChiari I malformation redefined: clinical and radiographic findings for 364 symptomatic patients. Neurosurgery. 1999;44(5):1005-1017."},{"issue":"23","key":"bib2","series-title":"N Engl J Med","first-page":"2191","article-title":"Congenital and acquired Chiari syndrome","volume":"390","author":"Friedlander","year":"2024","unstructured":"Friedlander RM.Congenital and acquired Chiari syndrome. N Engl J Med. 2024;390(23):2191-2198."},{"issue":"9","key":"bib3","series-title":"J Clin Med","first-page":"3287","article-title":"Overview of spontaneous intracranial hypotension and differential diagnosis with Chiari I malformation","volume":"12","author":"Bin Wan Hassan","year":"2023","unstructured":"Bin Wan Hassan WMNMistretta FMolinaro SOverview of spontaneous intracranial hypotension and differential diagnosis with Chiari I malformation. J Clin Med. 2023;12(9):3287."},{"key":"bib4","series-title":"Spinal Cord Ser Cases","first-page":"65","article-title":"Acquired Chiari malformation following spinal cord injury\u2014a case series","volume":"5","author":"McKean","year":"2019","unstructured":"McKean DZishan USBillingsley SAcquired Chiari malformation following spinal cord injury\u2014a case series. Spinal Cord Ser Cases. 2019;5:65."},{"issue":"3","key":"bib5","series-title":"Neurosurgery","first-page":"429","article-title":"Acquired Chiari malformations: incidence, diagnosis, and management","volume":"34","author":"Payner","year":"1994","unstructured":"Payner TDPrenger EBerger TSCrone KR.Acquired Chiari malformations: incidence, diagnosis, and management. Neurosurgery. 1994;34(3):429-434."},{"issue":"23","key":"bib6","series-title":"N Engl J Med","first-page":"2173","article-title":"Spontaneous intracranial hypotension","volume":"385","author":"Schievink","year":"2021","unstructured":"Schievink WI.Spontaneous intracranial hypotension. N Engl J Med. 2021;385(23):2173-2178."},{"key":"bib7","series-title":"World Neurosurg","first-page":"800","article-title":"Acquired Chiari malformation and syringomyelia secondary to space-occupying lesions: a systematic review","volume":"98","author":"Wang","year":"2017","unstructured":"Wang JAlotaibi NMSamuel NIbrahim GMFallah ACusimano MD.Acquired Chiari malformation and syringomyelia secondary to space-occupying lesions: a systematic review. World Neurosurg. 2017;98:800-808.e2."},{"issue":"4","key":"bib8","series-title":"J Neurosurg","first-page":"553","article-title":"Elucidating the pathophysiology of syringomyelia","volume":"91","author":"Heiss","year":"1999","unstructured":"Heiss JDPatronas NDeVroom HLElucidating the pathophysiology of syringomyelia. J Neurosurg. 1999;91(4):553-562."},{"issue":"1","key":"bib9","series-title":"AJNR Am J Neuroradiol","first-page":"7","article-title":"The \u201cpresyrinx\u201d state: a reversible myelopathic condition that may precede syringomyelia","volume":"20","author":"Fischbein","year":"1999","unstructured":"Fischbein NJDillon WPCobbs CWeinstein PR.The \u201cpresyrinx\u201d state: a reversible myelopathic condition that may precede syringomyelia. AJNR Am J Neuroradiol. 1999;20(1):7-20."},{"issue":"5","key":"bib1","series-title":"Neurosurgery","first-page":"1005","article-title":"Chiari I malformation redefined: clinical and radiographic findings for 364 symptomatic patients","volume":"44","author":"Milhorat","year":"1999","unstructured":"Milhorat THChou MWTrinidad EMChiari I malformation redefined: clinical and radiographic findings for 364 symptomatic patients. 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J Clin Med. 2023;12(9):3287."},{"key":"bib4","series-title":"Spinal Cord Ser Cases","first-page":"65","article-title":"Acquired Chiari malformation following spinal cord injury\u2014a case series","volume":"5","author":"McKean","year":"2019","unstructured":"McKean DZishan USBillingsley SAcquired Chiari malformation following spinal cord injury\u2014a case series. Spinal Cord Ser Cases. 2019;5:65."},{"issue":"3","key":"bib5","series-title":"Neurosurgery","first-page":"429","article-title":"Acquired Chiari malformations: incidence, diagnosis, and management","volume":"34","author":"Payner","year":"1994","unstructured":"Payner TDPrenger EBerger TSCrone KR.Acquired Chiari malformations: incidence, diagnosis, and management. 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World Neurosurg. 2017;98:800-808.e2."},{"issue":"4","key":"bib8","series-title":"J Neurosurg","first-page":"553","article-title":"Elucidating the pathophysiology of syringomyelia","volume":"91","author":"Heiss","year":"1999","unstructured":"Heiss JDPatronas NDeVroom HLElucidating the pathophysiology of syringomyelia. J Neurosurg. 1999;91(4):553-562."},{"issue":"1","key":"bib9","series-title":"AJNR Am J Neuroradiol","first-page":"7","article-title":"The \u201cpresyrinx\u201d state: a reversible myelopathic condition that may precede syringomyelia","volume":"20","author":"Fischbein","year":"1999","unstructured":"Fischbein NJDillon WPCobbs CWeinstein PR.The \u201cpresyrinx\u201d state: a reversible myelopathic condition that may precede syringomyelia. 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