Ulnar neuropathy in the forearm: A possible complication of diabetes mellitus

Ulnar neuropathy in the forearm is an unusual cause of hand weakness and sensory loss that is most often attributed to compression of the nerve distally within the humero-ulnar arcade (cubital tunnel). An association with diabetes mellitus, however, has not been reported. We identified four patients with type I diabetes mellitus and clinical findings suggestive of ulnar neuropathy in whom electrophysiologic testing revealed partial conduction block or abnormal temporal dispersion within the forearm segment of the ulnar nerve. Although evidence for a mild underlying polyneuropathy was present in three patients, the ulnar nerve abnormalities were disproportionately severe. In all cases, a Martin-Gruber anastomosis was excluded. Whether this lesion is due to an increased propensity to focal compression of the ulnar nerve within the humero-ulnar arcade or whether it represents a localized manifestation of the generalized polyneuropathy remains to be determined.