Destructive dural ectasia of dorsal and lumbar spine with cauda equina syndrome in a patient with ankylosing spondylitis.

We present a patient with longstanding ankylosing spondylitis complicated with cauda equina syndrome. The patient suffered from increasing pain in the leg with reduced sensitivity and extremely cold feet associated with incontinence. Diagnostic workup revealed dural ectasia, arachnoiditis and a spinal inflammatory mass leading to extensive vertebral bone destruction. Of interest, this was not only found in the lumbar spine region (which is typical in cases of cauda equina syndrome associated with ankylosing spondylitis) but also in the lower cervical spine (C7) and upper dorsal spine. Moreover, the bone destructive phenotype of this complication of long-standing AS contrasts with the usual characteristics of new bone formation and ankylosis. As initial treatment with anti-inflammatory drugs was not sufficiently successful, infliximab therapy was started which resulted in manifest clinical improvement as chronic pain, incontinence and laboratory signs of inflammation progressively disappeared.