Long-term clinical and neurologic recovery in the hand after surgery for severe cubital tunnel syndrome

Abstract

Purpose Functional outcomes of cubital tunnel surgery may decline as the severity of preoperative ulnar neuropathy increases. When functional recovery will be adequate, or whether tendon transfers should be required, may be unclear. We investigated the extent of functional recovery, the duration of the recovery process, and the necessity of restoring intrinsic muscle function in patients with severe cubital tunnel syndrome after surgery. Methods We retrospectively studied outcomes after cubital tunnel release in 15 patients with marked intrinsic muscle atrophy, claw-hand deformity, immeasurable (electrically silent) sensory and motor nerve conduction velocities, and Semmes-Weinstein test (SWT) results ranging from purple (3.84–4.31) to red (4.56–6.65). We evaluated subjective (numbness and activities of daily living [ADL] disturbances), objective (manual muscle testing [MMT] of index-finger abduction, and SWT), and neurophysiologic (nerve conduction velocity) outcomes. Overall functional outcome was evaluated by Akahori’s criteria. Results At a median follow-up evaluation of 4.5 years all outcomes had improved. Numbness was gone in 5 patients and greatly reduced in 9 patients; 6 patients reported slight difficulties in ADLs; and 9 patients had no difficulties. Motor nerve conduction velocity was measurable (mean, 35.3 m/s) in all 15 patients and sensory nerve conduction velocity was measurable (mean, 43.4 m/s) in 12. Recoveries in nerve conduction velocities persisted beyond 2 years. The SWT results were blue (3.22–3.61) in 6 patients, purple (3.84–4.31) in 8 patients, and red (4.56–6.65) in 1 patient. MMT of index finger abduction was grade 4 or 5 in 11 of 15 patients. Half the patients over 70 years old, however, were grade 3 or less. Akahori’s criteria were excellent in 3 patients, good in 6 patients, and fair in 6 patients. Conclusions Patients with severe intrinsic muscle atrophy and absent motor and sensory nerve conduction velocities can expect satisfactory long-term functional results after surgery. Function continues to improve beyond 2 years. Restoring index finger abduction is not always necessary for ADLs, although recovery requires several years and is poorer in the elderly.