Arachnoid veils and the Chiari I malformation.
OBJECTIVE
The literature contains scant data regarding variations in anatomy at the level of the foramen of Magendie in patients with Chiari I malformation and syringomyelia.


METHODS
Based on their operative experience and hospital data, the authors detailed the incidence of arachnoid veils found in juxtaposition to the foramen of Magendie in patients with hindbrain herniation. Additionally, radiological studies were retrospectively reviewed in cases in which such an anomaly was noted intraoperatively. Of 140 patients with Chiari I malformation who underwent decompressive surgery, an associated syrinx was demonstrated in 80 (57%). The foramen of Magendie was obstructed by an arachnoid veil in 10 (12.5%) of these patients; once the lesion was punctured, the cerebrospinal fluid drained freely from this median aperture. On retrospective review of imaging studies, none of these anomalous structures was evident. In all patients with an arachnoid veil and syringomyelia resolution of syringomyelia was revealed on postoperative imaging.


CONCLUSIONS
In the absence of a clear pathophysiology of syrinx production, the authors would recommend that patients with syringomyelia and Chiari I malformation undergo duraplasty so that, if present, these veils can be fenestrated.
Department of Cell Biology, University of Alabama at Birmingham, USA. richard.tubbs@ccc.uab.edu
R Shane
RS
Tubbs
Matthew D
MD
Smyth
John C
JC
Wellons
W Jerry
WJ
Oakes
D000293:Adolescent; D000328:Adult; D001099:Arachnoid / Q000002:abnormalities* / Q000601:surgery; D001139:Arnold-Chiari Malformation / Q000150:complications* / Q000601:surgery*; D002648:Child; D002675:Child, Preschool; D003388:Cranial Fossa, Posterior; D019299:Decompression, Surgical; D005260:Female; D005539:Foramen Magnum / Q000002:abnormalities* / Q000601:surgery; D006801:Humans; D008297:Male; D012189:Retrospective Studies; D013595:Syringomyelia / Q000150:complications* / Q000601:surgery*