OBSERVATIONS ON SEVERE ULNAR NEUROPATHY IN DIABETES

We describe the clinical and neurophysiologic findings in a group of d iabetic patients with a severe ulnar neuropathy. All patients attendin g a large inner-city diabetes center were prospectively screening for hand wasting and weakness due to ulnar nerve disease. Twenty diabetic patients fulfilling the clinical criteria underwent nerve conduction s tudies and electromyography. All but one patient with a motor ulnar ne uropathy had systemic complications, mostly severe: ten were amputees, four had had a renal transplant, and two were blind. The onset of han d weakness was sudden in five. All patients had a classical ''ulnar ha nd'' (bilateral in five) but forearm muscles were little affected. Sen sory loss was prominent in only one-half. Nerve conduction studies sho wed markedly reduced ulnar motor responses (mean, 1.2 mV versus 7.4 mV in controls) and ulnar/median motor ratios. Motor conduction was disp roportionately slowed across the elbows, with or without conduction bl ock, in only eight of 34 affected ulnar nerves. Five of these patients had a habit of leaning on their elbows and/or a Tinel's sign. Median sensory action potentials (SAPs) were recordable in 12 patients but ul nar SAPs were absent in 30 of 34 affected nerves. Electromyography rev ealed advanced denervation of ulnar supplied hand muscles. We conclude that motor ulnar neuropathy is not uncommon in patients with diabetes of long standing, especially in those with severe systemic complicati ons. Nerve entrapment at the elbows occurs in some, but in many the le sion is axonal, and damage may occur through ischemia. (C) 1998 Elsevi er Science Inc.