The Motor Network in Essential Tremor: Mechanisms of Therapy

Study Summary

Essential tremor (ET) is among the most common movement disorders, and is the most prevalent tremor disorder. It is a progressive, degenerative brain disorder that results in increasingly debilitating tremor, and afflicts an estimated 7 million people in the US (2.2% of the population) and estimates from population studies worldwide range from 0.4% to 6.3%. ET is directly linked to progressive functional impairment, social embarrassment, and even depression. Intention (kinetic) tremor of the arms occurs in approximately half of ET patients, and is typically a slow tremor (\~5-10Hz) that occurs at the end of a purposeful movement, and is insidiously progressive over many years. Based on direct and indirect neurophysiological studies, it has been suggested that a pathological synchronous oscillation in a neuronal network involving the ventral intermediate nucleus (Vim) of the thalamus, the premotor (PM), primary motor (M1) cortices, and the cerebellum, may result in the production of ET. In spite of the numerous therapeutic modalities available, 65% of those suffering from upper limb tremor report serious difficulties during their daily lives. Deep brain stimulation (DBS) has emerged as an effective treatment option for those suffering from medically refractory ET. The accepted target for ET DBS therapy is the Vim thalamus. Vim projects to PM, M1, and supplementary motor areas (SMA) and receives afferents from the ipsilateral cerebellum. Moreover, electrophysiological recordings from Vim during stereotactic surgery have identified "tremor cells" that synchronously discharge with oscillatory muscle activity during tremor. Clinical and computational findings indicate that DBS suppresses tremor by masking these "burst driver" inputs to the thalamus. The overall goal is to investigate the neural signatures of tremor generation in the thalamocortical network by recording data during DBS implantation surgery. Investigators will record data from the macroelectrode implanted

Primary Outcome

FHC Guideline 4000+ system or Medtronic devices will be connected to Ad-Tech Medical Instrumentation Corp. electrodes and deep brain electrodes to measure brain signals between the groups

Conditions Studied

Interventions

• PROCEDURE Deep brain stimulation implantation surgery
• DEVICE Ad-Tech Medical Instrumentation Corp. electrodes/subdural strips
• DEVICE FHC Guideline 4000+ system and/or Medtronic RC+S

Study Locations (1)