Electrophysiological study of patients with spinocerebellar and Friedreich's ataxia

Abstract

Objective: Spinocerebellar (SCA) and Friedreich’s ataxia (FRDA) patients were selected in order to undergo standardized protocol for the evaluation of bioelectrical activity of their nerves and muscles. We aimed to gather information on the severity anddistribution of their peripheral nerve involvement.Methods: Eighteen genetically proven SCA and FRDA patients were examined during this study and a control group of 31 agematched healthy individuals was formed. Both groups underwent conduction studies of sensory and motor nerves, F waves,needle EMG of proximal and distal muscles, and motor unit number estimations (MUNE) of selected muscles on upper and lowerextremities.Results: Amplitudes of all sensory nerves, as well median and peroneal motor amplitudes were low. Median, ulnar, tibial, andperoneal motor conduction velocities were significantly slowed. MUNE in abductor pollicis brevis and tibialis anterior muscleswere significantly lower. Needle EMG testing of respective muscles showed neurogenic involvement in the third of the patients.Conclusion: Polyneuropathy is frequently detected in SCA and FRDA patients. The sensory nerves in lower extremities werepredominantly involved; however motor dysfunction was also noted. MUNE can offer quantitative information on motor nervefiber and motor neuron involvement. Nerve conduction studies and needle EMG demonstrate clinical or subclinical polyneuropathy in patients with SCA and FRDA ataxia. MUNE might present another parameter for peripheral involvement.