Antidyskinetic effect of stereotactic interventions in the ventrointermedial nucleus of the thalamus in patients with Parkinson’s disease

Abstract

Objective. To investigate the peculiarities of the antidyskinetic effect of stereotactic interventions in ventrointermedial (Vim) thalamic nucleus in patients with Parkinson’s disease (PD).Materials and methods. Ventrointermedial thalamotomy (Vim-thalamotomy) for resistant tremor was performed in 10 patients with initial levodopa-induced dyskinesias (LIDs), which were considered as the secondary symptoms and were not taken into account when selecting the nucleus target (group 1). The study also includes 8 patients with LIDs developed due to disease progression after the Vim-thalamotomy performed earlier (group 2).Results. In group 1 after Vim-thalamotomy, 9 out of 10 patients had LIDs control in the contralateral limbs. A similar clinical observation was found in all 8 patients in group 2: while LIDs manifested on the ipsilateral side of the previously performed Vim-thalamotomy, they did not develop on the contralateral side. Such apparent antidyskinetic effects of our Vim-thalamotomіes contradict contemporary knowledge about the anatomical and pathophysiological features of LIDs.Conclusions. The control of LIDs after Vim-thalamotomy in patients with PD may indicate the afferent pallidal projections of ventrolateral thalamus involvement into the lesion. Combined anti-tremor and antidyskinetic effects are possible with the localization of the stereotactic target 3 mm behind the midcommissural point and/or with the diagonal trajectory of the electrode with an uninsulated tip of 4 mm in length. Appropriate stereotactic coordinates can be recommended for the operation of choice for patients with PD with tremor — LID symptom complex.