Parvocellular Red Nucleus - A Neuromodulation Target for Medically Refractory Meige Syndrome? (P01.239)

Abstract

Objective: To study the behavioral and motor responses following chemical modulation of parvocellular red nucleus in primates. Background Craniocervical dystonias are the most common forms of adult-onset focal dystonia. Blepharospasm, oromandibular, lingual, laryngeal and cervical dystonia are the various form of craniocervical dystonia. Meige syndrome is characterized by blepharospasm, cervical dystonia, and facial oromandibular dystonia. There is a growing interest in the use of deep brain stimulation (DBS) in medically refractory forms of dystonia but the optimal target for Meige syndrome remains unclear. Design/Methods: Experiments were performed using Cynomaglous monkey (Macaca Fascicularis). Monkey was trained to perform a self initiated behavioral task of reaching out and grabbing presented food reward for 6 weeks. After behavioral training implant surgery was performed. Neural activity within parvocellular red nucleus was identified and mapped using tungsten microelectrodes (10-30 m tip exposure length). Micropipettes ( 10μ m tip opening diameter) were used to record neural activity and to perform activation of parvocellular red nucleus by injecting Bicuculline(100nl), Kainic Acid(200nl,0.25 Mmol) and Gabazine (250 nl,0.2 Mmol). To avoid any residual effects injections were made at weekly intervals. Ten minutes after the injection, micropipette was removed and monkey was observed for any behavioral change. Results: Following Bicuculline injection dystonic tremors were noticed in the contralateral distal hindlimb. Contralateral focal dystonia of the neck and oro-facial dystonia including jaw deviation was noted with Gabazine injection. Kainic acid stimulation caused hypervigilence and contralateral focal dystonia of neck along with circling motion to side contralateral to injection. These motor responses were short lasting and reversible. Topography of stimulation site was correlated with histology after completion of experiments. Conclusions: Chemical neuromodulation of parvocellular red nucleus causes cervical and oromandibular dystonia. Further studies are needed to verify these changes and evaluate the target as potential site for neuromodulation of medically refractory Meige syndrome. Disclosure: Dr. Deep has nothing to disclose. Dr. Pati has nothing to disclose. Dr. Dhall has received personal compensation for activities with Teva Pharmacuticals as a speaker. Dr. Lieberman has nothing to disclose. Dr. Horn has nothing to disclose. Dr. Horn has nothing to disclose.