EMG Analysis in Disorders of Extrapyramidal Systems (About Basal ganglia and cerebellum)

Seo, Man Wook; Dubinsky, Richard

Abstract

BACKGROUND: Although several investigators have been studying EMG activity in projected movment, a complete and satisfactory understanding of the EMG patterns is still lacking. This present study is an attempt to define these patterns for certain stereotyped movement in a normal population, and to investigate the electrophysiologic mechanisms of abnormal movements in extrapyramidal disorders.
METHODS
5 Patients with Parkinson's disease and 5 patients with cerebellar disease performed several different stereotyped elbow flexion tasks, and the EMG patterns from biceps and triceps were compared with control group.
RESULTS
In patients with Parkinson's disease characterized, EMG pattern during a smooth felxion task was almost always abnormal and was chracterised by alternating activity in biceps and triceps. The EMG patterns during a fast flexion task were also usually abnormal although they were always composed of bursts of EMG activity of normal duration appearing alternately in the agonist and antagonist muscles. So, This study demonstrates that both slow and fast movement are clearly abnormal in these patients with diesase of the basal ganglia. In a task designed to investigate antagonist inhibition before agonist activity, a majority of the patients performed normally.
CONCLUSIONS
This study suggest that, contrary to previous claims, slowness of movement is not due either to failure to relax or to rigidity of agtagonist muscles. In patients with cerebellar disease, EMG pattern during a fast flexion task showed prolongation of the initial biceps and/or triceps components, and it is suggested that this abnormality might be an elemental featrure of dysmetria. 3 of 5 patients showed the normal pattern of smooth felxion indicating that, with cerebellar deficits, smooth movements are better preserved than fast movements. The timing of the cessation of triceps activity before the initiation of biceps activity in an alternating movement was abnormal in 4 of 5 patients; this abnormality might be an elemental feature of dysdiadochokinesia.