O100 CMAP scan in diagnosis and follow-up of patients with amyotrophic lateral sclerosis

Abstract

Objective Compound muscle action potential scanning (CMAP scan) is a non-invasive electrophysiological tool that allows observation of the whole-range of the functional motor unites in a muscle. The objective of this study is to assess the changes in CMAP scan from abductor pollicis brevis (APB) and abductor digiti minimi (ADM) muscles during the diagnosis and follow up period in amyotrophic lateral sclerosis (ALS) patients. Method Seventeen patients with ALS and 15 healthy controls (HCs), were included in the study. Five hundred stimuli were applied with equal steps in descending order at 2 Hz, in order to generate a CMAP scan curve. The data were exported to Microsoft Excel 2007. Backward step% step%, gap%, D50 were calculated. Results Backward step% step%, gap%, D50 values for ADM muscle were 264, 22.6, 27.9, 23.4 in ALS and 179.3, 1.9, 1.8, 46.7 in the control group, respectively (p ⩽ 0.05, between ALS and HC groups). Backward step% step%, gap%, D50 values for APB muscle were 500.6, 41.3, 39.9, 20.5 for ALS group and 241.7, 3.6, 3, 46.4 for the control group (p ⩽ 0.05, between ALS and HC groups). In ALS patients, backward step%, step%, gap% were found to be more severely affected in APB muscle. Follow-up studies of 6 patients showed significant difference in step%, gap% in APB muscle and D50, step% in ADM muscle. Conclusion CMAP scan is a sensitive electrophysiological method for showing the motor unit changes caused by ALS and for observing the effects of split-hand phenomenon.