Objective: To reveal the electrophysiological mechanism of voluntary movements with and without neck muscle exertion in patients with cervical dystonia.

Background: Globus pallidus, as part of the basal ganglia, participates both in direct and indirect pathways allowing movement to proceed. It has been proposed that the hyperkinetic symptoms seen in dystonia arise from abnormally low firing rates (FR) of the neurons in the globus pallidus internus (GPi). Improvement of cervical dystonia during continuous bilateral stimulation of the globus pallidus internus was demonstrated. However, neuronal mechanism of motor signal transmission in globus pallidus remains unclear.

Methods: Extracellular recordings were obtained during stereotactic surgery for bilateral implantation of DBS electrodes in the GPi from 7 patients with cervical dystonia. Operations were performed under local anesthesia. EMGs of hand and neck muscles as well as phonogram were recorded simultaneously with microelectrode recording. Patients were presented motor tests with and without the involvement of the neck muscles.

Results: It has been shown that neuronal activity of external (GPe) segment of the globus pallidus was characterized by predominantly burst patterns of activity (FR=50, Cv=1,1) while internal (GPi) segment was characterized by the same firing rate but predominantly tonic patterns of activity (FR=43, Cv=0,7). GPe neurons were reacted on voluntary movement by complicated multicomponent responses. First short-term activatory or inhibitory response as a rule was observed before the onset of EMG changes, while second tonic response was observed during movement performance. GPi neurons were reacted by single component tonic activation during movement performance. Neurons selectively responded to voluntary movement without and with neck muscle exertion were found in both segments of globus pallidus.

Conclusions: The obtained data suggest from one side that globus pallidus involved in both function – preparation and realization of voluntary movement from another side both segments of the globus pallidus involved in the mechanisms of head movement in patients with cervical dystonia.

Neural mechanisms of sensory and motor signals transmission in the interstitial nucleus of Cajal in patients with cervical dystonia were previously demonstrated.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/single-unit-activity-of-globus-pallidus-during-voluntary-movements-in-patients-with-cervical-dystonia/