TY - JOUR T1 - Patterns of Intrathecal Ossification in Arachnoiditis Ossificans: A Retrospective Case Series JF - American Journal of Neuroradiology JO - Am. J. Neuroradiol. SP - 228 LP - 234 DO - 10.3174/ajnr.A7764 VL - 44 IS - 2 AU - B. Thejeel AU - C.S. Geannette AU - M. Roytman AU - D.J. Pisapia AU - J.L. Chazen AU - S.T. Jawetz Y1 - 2023/02/01 UR - http://www.ajnr.org/content/44/2/228.abstract N2 - SUMMARY: Arachnoiditis ossificans is an uncommon end-stage appearance of chronic adhesive arachnoiditis. Imaging features of arachnoiditis ossificans are characteristic and should be diagnosed to avoid unnecessary intervention and guide prognosis and management. In this case series, we retrospectively analyzed CT and MR imaging of 41 patients to identify common patterns of intrathecal ossification and present the common etiologies. Thirty-two patients had a confirmed history of spinal instrumentation, 7 were discovered on imaging without prior surgical history, 1 had a history of ankylosing spondylitis, and 1 had trauma. The most frequent site of ossification was at the conus and cauda equina. Four patterns of ossification were identified, including central, nerve root encasing, weblike, and peripheral. Arachnoiditis ossificans is an important, likely under-recognized consideration in patients who present with back pain. Diagnosis can be made readily on CT; MR imaging diagnosis is also possible but may be challenging.AOarachnoiditis ossificans ER -