Diagnostic and Prognostic Usefulness of Proximal Radial Motor Nerve Conduction Study in Acute Compressive Radial Neuropathy

J Korean Assoc EMG Electrodiagn Med 2011;13(1):12-17.
Published online June 1, 2011.

Abstract

Objective: To demonstrate diagnostic and prognostic usefulness of electrodiagnostic study in evaluating acute compressive radial neuropathy. Methods: We reviewed the medical records of acute compressive radial neuropathy with electrodiagnostic study between January 2007 and December 2009, and we recruited 28 patients. We interviewed all the patients by telephone to find out the final neurologic status. Results: Female to male ratio was 4:24 and most of them had normal body mass index. The entire patient had good recovery and we could dichotomize to ‘Almost normal (24 cases)’ and ‘Good (4)’ group. Only 2 patients showed low amplitude of sensory nerve action potential of superficial radial nerve, but conduction block of radial nerve was demonstrated on 18 cases (64.3%) between elbow and Erb’s point. In clinical evaluation, initial motor grade of wrist and finger joint (MPJ) was important because recovery time of patients with MRC grade 2 or less showed significantly longer than that with MRC grade 3 or more (83.8 ±57.6 days vs. 37.1±19.7 days, p<0.05). The degree of radial nerve conduction block was related with recovery time of motor weakness (linear regression; β=-0.43 p<0.05). Conclusion: Radial motor nerve conduction study including Erb’s point stimulation is useful method to evaluate acute compressive radial neuropathy. Furthermore, it is also useful to predict the duration of motor weakness.

Key Words: Saturday night palsy, Nerve conduction study, Radial nerve