Lumbar radiculopathy in ankylosing spondylitis with dural ectasia.

We present a 57-year-old man with ankylosing spondylitis (AS) and significant dorsal lumbar dural ectasia (diverticulum). An L5 nerve root monoradiculopathy associated with AS has not been previously reported. The quantity and extent of such ectasia is variable but may be related to cauda equina syndrome. Long-term follow-up of these cases may reveal whether or not solitary nerve lesions gradually lead to cauda equina syndrome. We recommend that asymptomatic or symptomatic patients with dural ectasia should be closely observed without need for immediate surgical intervention.