DBS

Thalamic stimulation is an invasive surgical procedure that seems to mimic the positive effects of surgical ablation performed during a thalamotomy. In general, the results are equal to or better than those reported in patients with ET who have had a thalamotomy, and thalamic stimulation is believed to be an effective means of treating ET in selected patients. Thalamic deep brain stimulation may effectively improve limb tremor in patients with ET. However, in other patients, tremor may not be eliminated and may continue to cause some degree of impairment.

During this procedure, electrodes are implanted in a specific area of the brain (i.e., ventral intermediate [Vim] nucleus of the thalamus). In addition, a device known as an implantable pulse generator (IPG) is placed under the skin (subcutaneous) in the area of the collarbone. After appropriate postoperative testing, leads from the implanted electrodes are connected to the pulse generator, which then delivers continuous high frequency electrical stimulation to the thalamus via the implanted electrodes. This form of stimulation helps the thalamus "rebalance" the control messages in the movement control centers of the brain, serving to suppress the tremor. Patients may turn the pulse generator off and on by passing a hand-held magnet over the device. The batteries that power the pulse generator need to be surgically replaced every 3 to 5 years.

In ET patients, adverse events due to thalamic stimulation are generally mild. The intensity of complications or side effects usually correlates with the intensity of stimulation. The possible complications of thalamic stimulation include mild dysarthria, weakness on one or both sides of the body, or disturbance of normal balance (dysequilibrium). In most cases, unusual sensations (paresthesias) such as numbness or tingling in the head and hands may occur after surgery; however, these sensations typically resolve with ongoing adjustment of the stimulator settings. About 6% of patients experience marked dysarthria or permanent, though tolerable, paresthesias.

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