16. Deep Brain Stimulation

Deep brain stimulation is used as a substitute for permanent neuroablative procedures (destruction/inactivation of nerve tissue by surgery, injections, lasers, etc.) in the management of disorders associated with movement, notably Parkinson’s disease, essential tremor, and dystonia. The technique involves stereotactic placement of an electrode into the identified area of the brain and delivering electrical pulses to that area. “Stereotactic surgery or stereotaxy” relates to “stereo-axis,” a combination of “stereo” and “taxis,” originating from “stereo” meaning “three-dimensional” + Greek “taxis” meaning “orientation,” to direct the tip of an electrode in the brain. For the treatment of Parkinson’s disease in sophisticated phase, the target area of the brain is subthalamic nucleus (STN). For medically refractory tremor, the focal area is ventral intermediate nucleus (Vim) of the thalamus. For both cervical and generalized dystonias and Parkinson’s disease, the area of interest is the globus pallidus internus (GPi). Therapeutic stimulation parameters generally used are amplitude, pulse duration, and frequency. The high-frequency stimulation (100–200 Hz) given in this method impersonates the effects of surgical ablation. The method combines the advantages of adjustability of stimulus parameters with the reversibility of treatment. These merits have enabled deep brain stimulation to largely supersede the ablation practice.