Posttraumatic arachnoidal diverticula.

Arachnoidal diverticula of the spinal cord and nerve roots are relatively common lesions. Many of these lesions are congenital, but some may occur as a result of trauma or spinal surgery. This report reviews the Mayo Clinic experience with postsurgical and traumatic lesions. Of the 17 patients in the series, 11 had previous operation in the region of the lesion and 6 had nonsurgical trauma.