Spinal Arachnoiditis Ossificans: Report of Quadruple-Triggered Case

BACKGROUND: Arachnoiditis ossificans (AO) is a rare condition often associated with previous spine surgery. Here we describe a unique case of a patient affected by ankylosing spondylitis (AS), presenting with progressive neurologic deterioration due to AO. We also review the literature on evaluation and management of patients suffering from AO. CASE DESCRIPTION: The 65-year-old patient had a history of previous spinal trauma and related thoracolumbar surgery. Magnetic resonance imaging revealed multiloculated intradural/extramedullary cysts on the posterior surface of the spinal cord at Th9-L1, with clustered nerve roots. Computed tomography, with 3-dimensional reconstruction, demonstrated a likely ossification of both the dura and arachnoid from Th9 to S1. Microsurgical debridement of scar tissue from previous surgery, drilling of posterior ossified plaques at Th11-Th12-L1, and marsupialization and drainage of arachnoid cysts at Th11-Th12 were performed. CONCLUSIONS: We submit that AS, spinal trauma, epidural hematoma, and related surgery may be synergistic and independent factors in the etiopatho-genesis of AO. This should be considered in patients with AS and/or a history of spinal surgery who present neurologic worsening.