Effect of 25 Hz Repetitive Transcranial Magnetic Stimulation on Motor Performance and Cortical ' ) , Excitability on Patients with Parkinson's disease; /•-., Neurophysiological and Laboratory study

Abstract

Parkinson's disease (PD) is the second most common age-related, progressive neurodegenerative disorder after Alzheimer's disease affects nearly 2% of the population over age 65 (Corti et al., 2005). Although the motor symptoms of PD are mainly treated with drugs, the clinical utility of these medications tends to become limited over the years, often due to adverse effects such as dyskinesia (Olanow et al., 2001). Repetitive transcranial magnetic stimulation (rTMS) ts a tool that allows noninvasive stimulation of the cerebral cortex and although many researchers have used TMS to understand PD pathophysiology, only a few have used it in therapeutic trials (Lomarev et al., 2006). Transcranial magnetic stimulation can be used to measure various parameters in motor cortex, allowing us to evaluate different aspects of cortical excitability (Hallett et al., 1999). Such measures are useful in understanding the changes in brain physiology seen in the setting of cortical plasticity and brain disorders (Hallett, 2000).

The aims of the present study are: (I) To study the effects of rTMS (frequency dependent and position dependent) on motor performance on large sample of unmedicated PD patients. (2) To study the after effects of 25Hz rTMS over the primary motor cortex on the corticospinal excitability. (3) To investigate whether rTMS could change the serum dopamine level in PD patients and correlate the changes of dopamine level with the changes in clinical score and cortical excitability.