{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,6]],"date-time":"2026-02-06T05:34:29Z","timestamp":1770356069328,"version":"3.49.0"},"reference-count":20,"publisher":"Journal of Neurosurgery Publishing Group (JNSPG)","issue":"2","license":[{"start":{"date-parts":[[2021,1,11]],"date-time":"2021-01-11T00:00:00Z","timestamp":1610323200000},"content-version":"unspecified","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2021,1,11]]},"abstract":"<jats:sec>\n                    <jats:title>BACKGROUND<\/jats:title>\n                    <jats:p>Secondary Chiari malformation can be caused by various disorders associated with cerebrospinal fluid (CSF) leakage at the spinal level. In this report, the authors describe a rare case of secondary Chiari malformation caused by excessive CSF absorption through the enlarged spinal arachnoid villi\u2013like structure.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>OBSERVATIONS<\/jats:title>\n                    <jats:p>A 20-year-old woman presented with progressive severe headache and posterior neck pain. Magnetic resonance imaging showed tonsillar herniation and decreased subarachnoid space around the spinal cord. A hypointense signal area was observed in the ventral spinal canal on a T2-weighted image. An axial image revealed multiple small, arachnoid cyst\u2013like structures at the right T1 nerve root sleeve. Direct surgery revealed that the cyst-like structures were continuous with the arachnoid membrane and protruded into the abnormally large epidural venous sinus. The cyst-like structures were resected, and the dural sleeve was repaired using fascia. The patient showed good improvement of symptoms after surgery.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>LESSONS<\/jats:title>\n                    <jats:p>Excessive CSF absorption through the enlarged spinal arachnoid villi\u2013like structure can cause secondary Chiari malformation. Neurosurgeons should be aware of this unusual mechanism of CSF leakage. Simple posterior fossa decompression will be ineffective or even harmful.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.3171\/case2049","type":"journal-article","created":{"date-parts":[[2021,1,29]],"date-time":"2021-01-29T15:32:32Z","timestamp":1611934352000},"source":"Crossref","is-referenced-by-count":0,"title":["Secondary Chiari malformation due to enlarged spinal arachnoid villi\u2013like structure: illustrative case"],"prefix":"10.3171","volume":"1","author":[{"given":"Izumi","family":"Koyanagi","sequence":"first","affiliation":[{"name":"Department of Neurosurgery, Hokkaido Neurosurgical Memorial Hospital, Sapporo, Hokkaido, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yasuhiro","family":"Chiba","sequence":"additional","affiliation":[{"name":"Department of Neurosurgery, Hokkaido Neurosurgical Memorial Hospital, Sapporo, Hokkaido, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Hiroyuki","family":"Imamura","sequence":"additional","affiliation":[{"name":"Department of Neurosurgery, Hokkaido Neurosurgical Memorial Hospital, Sapporo, Hokkaido, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Masami","family":"Yoshino","sequence":"additional","affiliation":[{"name":"Department of Neurosurgery, Hokkaido Neurosurgical Memorial Hospital, Sapporo, Hokkaido, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Toshimitsu","family":"Aida","sequence":"additional","affiliation":[{"name":"Department of Neurosurgery, Hokkaido Neurosurgical Memorial Hospital, Sapporo, Hokkaido, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1754","reference":[{"key":"b1","series-title":"J Clin Neurosci","doi-asserted-by":"publisher","first-page":"486","DOI":"10.1016\/j.jocn.2019.12.033","article-title":"Multifocal Gorham-Stout disease associated with Chiari I malformation and recurrent aseptic meningitis: case report and review of literature","volume":"72","author":"Stephens S","year":"2020","unstructured":"Stephens S, Squires L, Campbell R, . 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