Objective: The goal of the study was to find differences in spontaneous and neck-related activity of pallidal and cerebellar receiving thalamic nuclei in patients with cervical dystonia.

Background: Contemporary hypotheses for cervical dystonia (CD) suggest the role of altered neuronal activity in basal ganglia and thalamus to play the key role in the development of dystonic movement disorders, whereby distorted outflow of pallidal receiving area of thalamus appear to have resulted in dystonic postures, whereas the cerebellar receiving area contribute to myoclonic jerks (Guehl et al., 2000). At the same time, ventrooral internus nucleus as a component of the vestibulo-interstitial-thalamo-cortical circuit is known to be involved in head turning. Thus, analysis of neck-related activity in ventral thalamic nuclei in CD patients is of particular interest.

Methods: We analyzed single-unit activity of ventraoral thalamic nuclei recorded during the micro-electrode-guided surgical ablation procedures in patients with cervical dystonia under local anesthesia. We separated neurons to burst and tonic type of activity and performed parametric analysis of each cells. Neuronal responses to neck movement performance, passive and abnormal involuntary dystonic movements were analyzed in relation to EMG changes of neck muscles.

Results: We found both tonic and burst activity in cerebellar and pallidal receiving nuclei. Most burst cells of pallidal receiving nuclei was characterized as rhythmic LTS burst. In contrast, burst cells of cerebellar receiving nuclei was characterized by sparse non-rhythmic activity. We found neck-related cells mainly in cerebellar receiving nuclei. Unit responses was characterized by prolonged excitation on active, passive and involuntary neck muscle exertion. The pallidal receiving ventrooral thalamic nuclei responded more nonspecifically to different motor tasks.

Conclusions: We found neck-related activity mostly in cerebellar receiving nuclei of human ventral thalamus in CD patients. These findings confirm the assumption of cerebellar participation in pathophysiology of cervical dystonia.

References: 1) Guehl D, et al. Bicuculline injections into the rostral and caudal motor thalamus of the monkey induce different types of dystonia. Eur J Neurosci 2000;12(3):1033-7.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/neuronal-responses-of-pallidal-and-cerebellar-receiving-thalamic-nuclei-to-neck-exertion-in-cervical-dystonia-patients/