Results of treatment of carpal tunnel syndrome with associated hourglass deformity of the median nerve.

Two hundred twenty-seven successive cases of carpal tunnel syndrome confirmed by abnormal electrodiagnostic studies were reviewed. All cases underwent open carpal tunnel release by a single surgeon over a 3-year period. Thirty-two hands (14% of all cases) in 29 patients demonstrated an hourglass deformity at the time of surgery. Electrodiagnostic tests revealed no evidence of any other type of peripheral neuropathy in any patient. Postoperative electrodiagnostic studies were obtained in all cases on completion of therapy. The length of the follow-up period averaged 11 months (range, 3-35 months). The duration of preoperative symptoms ranged from 2 years to more than 10 years. Twenty-eight of the 32 hands (88%) with hourglass deformities demonstrated subjective clinical improvement or complete resolution of symptoms. Chronicity of symptoms and electrophysiologic severity did not correlate with the presence of the hourglass deformity. Presence of hourglass compression of the median nerve in carpal tunnel syndrome is therefore not a negative prognostic indicator.