High frequency stimulation of the subthalamic nucleus and levodopa induced dyskinesias in Parkinson's disease

Open Access
Publisher Website
Google Scholar
Abstract
Reduction in the neuronal activity of the subthalamic nucleus leading to diminished excitation of the globus pallidum internum is associated with chorea-ballism in monkeys.1 Levodopa induced dyskinesias are currently thought to share a similar pathophysiology2 but recent findings also suggest that abnormal patterns of neuronal firing in the globus pallidum internum may be as relevant.3 Data from both parkinsonian monkeys and patients with Parkinson's disease submitted to lesion4 5 or functional blockade of the subthalamic nucleus6 are in keeping with such a general principle, but the threshold to induce dyskinesias in the parkinsonian state is higher than in intact animals.7 The case recently described by Figueiras-Mendez et al 8 is extremely interesting as it suggests that functional inhibition of the subthalamic nucleus by high frequency stimulation blockades levodopa induced dyskinesias. This is clearly at odds with the current pathophsyiological model of the basal ganglia.9 Thus, the finding of Figueiras-Mendez et al 8 rises the intriguing possibility that dyskinesias depend or are mediated by neuronal firing in a given region of the subthalamic nucleus, which was blocked by high frequency stimulation. Measurement of afferent synaptic activity by the technique of 2-deoxylucose (2-DG) uptake showed an increment in the subthalamic nucleus (compatible with increased inhibition from the globus pallidum externum), particularly in the ventromedial tip of the nucleus.9 This contrasts with the findings in monkeys with chorea induced by pharmacological blockade of the globus pallidum externum, in which 2-DG uptake was maximal in the dorsolateral portion of the subthalamic nucleus, where the sensorimotor region lies. A recent anatomical study10 also showed that the cortical-subthalamic … Dr F Jiménez-Jiménez, C/Corregidor, Jose de Pasamonte 24 3°D, E 28030 Madrid, Spain

This publication has 0 references indexed in Scilit: