Pallidotomy

Until the late 1990s, pallidotomy was the most common type of PD surgery; deep brain stimulation or DBS is now being performed more often. A pallidotomy involves destruction of part of the globus pallidus (GPi), a region of the brain involved with the control of movement. Destroying part of the GPi may help to restore the balance in that area of brain, which normal movement requires. Pallidotomy is performed by insertion of a wire probe into the GPi. Once its placement has been confirmed by electrical tests, the probe heats surrounding tissue by emission of radio waves. The heat destroys nearby tissue. Effects of the surgery are apparent almost immediately. Improvements from pallidotomy range from 70% to 90% reduction of dyskinesias and dystonia, and 25% to 50% for tremor, rigidity, bradykinesia, and gait disturbance. Levodopa dose may be reduced after the surgery, and dyskinesia improvement is based partly on this reduction.

Pallidotomy may be unilateral (one-sided) or bilateral (two-sided). Following a unilateral pallidotomy, improvements are primarily to the side of the body opposite to the lesioned side of the brain. Bilateral surgery is possible and improves dyskinesias further, but greatly increases the risk for worsening effects on cognition, swallowing, and speech; hence, it is done very rarely if at all.

Adverse effects of pallidotomy may include hemorrhage, weakness, visual deficits, speech deficits, and confusion, but the risk of these is relatively low in centers with an experienced surgical team. Weight gain is very common following surgery.

	Thalamotomy