Case of the Week
Section Editors: Matylda Machnowska1 and Anvita Pauranik2
1University of Toronto, Toronto, Ontario, Canada
2BC Children's Hospital, University of British Columbia, Vancouver, British Columbia, Canada
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March 26, 2012
Erosive Arachnoiditis
- Erosive arachnoiditis is a late and relatively infrequently recognized complication of ankylosing spondylitis.
- The main clinical manifestation is cauda equina syndrome.
- The pathogenesis of cauda equina is not well understood. It is likely secondary to chronic arachnoiditis, which results in nerve root inflammation/degeneration, fibrosis, and adhesions. Arterial/respiratory pulsatile forces transmitted through the CSF in a chronically inflammed thecal sac likely lead to formation of arachnoid pouches/diverticulae and erosive changes in the posterior elements of the vertebrae.
- Key Diagnostic Features: Empty appearance of the thecal sac, clumping of the nerve roots, arachnoid diverticulae formation with erosion of the posterior elements in a patient with ankylosing spondylitis
- DDx: Arachnoid cyst
- Rx: Lumboperitoneal shunting, symptomatic Rx
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