Submitted by: Elliot Bodofsky, MD
Edited by: Rocio Carolina Garcia Santibanez, MD
Pelosi L, Ming Yin Tse D, Eoin M, Chancellor A, Boland M. (2018). Ulnar neuropathy with abnormal non-localizing electrophysiology: Clinical, electrophysiological and ultrasound findings. Clinical Neurophysiology
. 129. 10.1016/j.clinph.2018.07.020.
Ulnar mono-neuropathy is non-localizable (NL-UN) when there is clinical ulnar neuropathy, reduced ulnar distal sensory and/or motor amplitude, but no focal slowing or focal loss of amplitude. This study investigated the frequency and severity (clinical and electrophysiologic) of NL-UN, and whether ultrasound of the nerve could assist in the diagnosis of NL-UN. One hundred thirteen patients referred for electrodiagnostic testing with signs and symptoms of ulnar neuropathy had electrodiagnostic testing. Sixty-four patients had reduced ulnar distal motor or sensory amplitude, 48 localizable (75%) and 16 (25%) non-localizable. The NL-UN patients were predominately male, had significantly more severe clinical findings and greater amplitude reduction than the localizable patients.
All NL-UN patients received ultrasound scanning of the ulnar nerve from the wrist to mid humerus. The ulnar diameter was measured at the widest area, and compared with normal values. All ultrasound studies were abnormal. Most of the patients (13/16, 81%) had evidence of focal enlargement at the elbow. The other 3 (19%) had evidence of diffuse ulnar enlargement. All 3 were diabetic, indicating probable diabetic neuropathy.
There is a fairly high incidence of NL-UN. Previous studies have shown some variation in incidence. All patients with NL-UN showed ulnar pathology on ultrasound, some quite severe, most with focal ulnar enlargement across the elbow. This strongly suggests that ultrasound evaluation should be considered in any case of non-localizable ulnar neuropathy.