Cerebellar stimulation for the treatment of dystonia: preclinical studies

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DESCRIPTION (provided by applicant): Dystonia is characterized by excessive involuntary muscle contractions that cause abnormal postures and twisting movements. Current treatments for dystonia are largely unsatisfactory or palliative. Small molecule drugs are ineffective in most patients. Botulinum toxin is effective but requires injection into affected muscles, limiting its ue to the treatment of dystonias that affect a small number of muscles. Deep brain stimulation (DBS) of the internal globus pallidus is another treatment option. Some patients, particularly those suffering from primary generalized dystonia experience tremendous benefits from pallidal DBS. However, many other patients, particularly those with secondary dystonias, experience little or no improvement, demonstrating a need for the identification and exploration of new treatment targets. Strong evidence implicates cerebellar abnormalities in dystonia and supports the idea that electrical stimulation of the cerebellum is an effective treatment for dystonia. Autopsy studies established a link between cervical dystonia and tumors of the cerebellum. Further, abnormal activity of the cerebellum is observed in many different forms of dystonia additionally, some cerebral palsy patients, who also often suffer from dystonia in addition to spasticity, have experienced improvement after cerebellar electrical stimulation. However, there are currently no studies examining the use of cerebellar stimulation in dystonia per se. Animal studies demonstrate that cerebellar abnormalities can cause dystonia. Abnormal cerebellar activity is observed in mouse and rat models of dystonia. In rat and mouse models, ablation of the cerebellum ameliorates dystonia. The effects of cerebellar stimulation have not yet been explored in animal models to test the idea that dystonia can be ameliorated using the non-ablative approach of electrical stimulation to interrupt abnormal signaling. Although cerebellar stimulation has been used in humans for decades, the use of cerebellar stimulation for the treatment of dystonia is surprisingly limited despite the strong evidence linking cerebellar dysfunction to dystonia in both human and animal studies. This proposal will systematically examine cerebellar stimulation for the treatment of dystonia in mouse models as preclinical proof-of-concept. The specific aims of this proposal are: Aim 1. To determine parameters of cerebellar stimulation that ameliorates dystonia. The effects of methodically varying stimulation parameters, including location, frequency, and amplitude and pulse width on dystonic and baseline activity are assessed in alert unrestrained mouse models of dystonia. Aim 2. to map the anatomical extent of stimulation. Because c-fos expression is routinely used to map electrical stimulation in brain, we will use the fos reporter TetTag mice to map extent of cerebellar stimulation. The success of this proposal will provide preclinical evidence to support an exploratory clinical study in humans for the use of cerebellar stimulation as a treatment for dystonia.