Movement Disorders: Anatomy and Physiology Relevant to Deep Brain Stimulation

This chapter focuses on the anatomy and physiology of various movement disorders that is relevant to deep brain stimulation (DBS). Functional neurosurgery has revolutionized the treatment of various movement disorders such as Parkinson's disease, essential tremor and dystonia. Concurrent with the development of deep brain stimulation have been advances in the understanding of the physiology of the target structures and the pathophysiological basis of movement disorders. Common targets for DBS are the subthalamic nucleus, the globus pallidus pars internus, and the ventralis intermedius nucleus of the thalamus. DBS is regarded as the gold standard for the surgical treatment of Parkinson's disease and other movement disorders as programmers can reverse or minimize side effects and optimize clinical benefit by modifying the contacts at which electrical pulses are delivered and altering the stimulation parameters of those pulses. The insights gained from the MPTP model of PD led first to the development of the “rate model” and then later recognition of abnormal oscillations and increased synchronization between structures that normally fire independently in the presence of dopamine. Improved insight into the pathophysiology of a neurological disorder has led to an evolution of DBS from experimental modality to the treatment of choice in advanced movement disorders.