Reconsideration of Ventrolateral Thalamotomy for Hyperkinesis

Abstract

Publisher Summary This chapter discusses the different aspects of ventrolateral (VL) thalamotomy for hyperkinesis. It is known that stimulation of the VL nucleus in both human and experimental animals evokes rhythmic potentials in the various cortical areas. The nerve is stimulated through two directly inserted needles or through two surface plate electrodes around it. Evoked electromyography is simultaneously recorded bipolarly through needles from the muscles innervated by the ulnar nerve. The recording electrode from the thalamus is the same one that is used for the thalamic stimulation. In cerebral palsied patients wherein general anesthesia was introduced, the negative-positive complex with diffuse distribution was not observed on stimulation of any areas within the thalamus. Instead, the specific complex was clearly observed on stimulations of several to 10 mm above the SP. The location capable of inducing the evoked potential similar to the augmenting response of the experimental animal in each case was considered as the physiologically determined VL nucleus, which enabled us to differentiate an area below the VL from the VL nucleus in observing the effects on motor symptoms by high frequency stimulation of parkinsonian patients.