Ulnar neuropathy. Incidence, outcome, and risk factors in sedated or anesthetized patients

Ulnar neuropathy is well-recognized as a potential complication of procedures performed on anesthetized patients. However, reported outcomes and risk factors for this problem are based on small series and anecdotes.

We retrospectively reviewed the perioperative courses of 1,129,692 consecutive patients who underwent diagnostic and noncardiac surgical procedures with concurrent anesthetic management at the Mayo Clinic from 1957 through 1991 (inclusive). The medical diagnoses of patients who had these procedures were scanned for 26 diagnoses associated with neuropathy. Persistent neuropathy of an ulnar nerve was defined as a sensory or motor deficit of greater than 3 months' duration. Risk factors anecdotally associated with persistent neuropathy were analyzed by comparing patients with an ulnar neuropathy with control subjects in a 1:3 case-control study.

Persistent ulnar neuropathies were identified in 414 patients, a rate of 1 per 2,729 patients. Of these, 38 (9%) patients had bilateral neuropathies. Approximately equal numbers of the neuropathies included sensory loss only or mixed sensory and motor loss. Initial symptoms form most neuropathies were noted more than 24 h after the procedure. Factors associated with persistent ulnar neuropathy included male gender and a duration of hospitalization of more than 14 days (P < 0.01). Neuropathy was more likely to develop in very thin and obese patients than in patients with average body habitus. Neither the type of anesthetic technique nor the patient position was found to be associated with this neuropathy. Of the 382 patients who survived the 1st postoperative yr, 53% regained complete motor function and sensation and were asymptomatic. Of those with neuropathies persisting for more than 1 yr, most had moderate or greater disability from pain or weakness.

These data suggest that perioperative ulnar neuropathies are associated with factors other than general anesthesia and intraoperative positioning. Men at the extremes of body habitus who have prolonged hospitalizations are particularly susceptible to development of ulnar neuropathies.