Type of Surgery
Last updated: 02/17/2009
Pallidotomy requires the insertion of a long needle-like probe deep into the brain through a hole in the top of the skull. In order to precisely locate the GPi target, and to ensure the probe is precisely placed in the target, a "stereotactic frame"...
is used. This device is a rigid frame attached to the patient's head, providing an immobile three-dimensional coordinate system, which can be used to precisely track the location of the GPi and the movement of the probe.
For unilateral pallidotomy, a single "burr hole" is made in the top of the skull; bilateral pallidotomy requires two holes. A strong topical anesthetic is used to numb the shaved area before this hole is drilled. Since there are no pain receptors in the brain, there is no need for deeper anesthetic. In addition, the patient must remain awake in order to report any sensory changes during the surgery. The lesion made in the GPi is very close to the optic tract that carries visual information from the eyes to the rear of the brain. Visual changes may indicate the probe is too close to this region.
Once the burr hole is made, the surgeon inserts a microelectrode probe, which is used to more precisely locate the GPi. Electrical stimulation of the brain through the electrode can help determine exactly which structure is being stimulated. This is harmless, but may cause twitching, light flashes, or other sensations. A contrast dye may also be injected into the spinal fluid, which allows the surgeon to visualize the brain's structure using one or more imaging techniques. During the procedure, the patient will be asked to make various movements to assist in determining the location of the electrode.
When the proper target is located, the electrode tip is briefly heated, carefully destroying the surrounding tissue to about the size of a pearl. If bilateral pallidotomy is being performed, the localizing and lesioning will be repeated on the other side.
Pallidotomy is a procedure where a tiny electrical probe is placed in the globus pallidus (one of the basal ganglia of the brain), which is then heated to 80 degrees celsius for 60 s, to destroy a small area of brain cells. Pallidotomy is used to treat dyskinesias in patients with Parkinson's disease.
Surgery for removal is generally advised for patients with limited cancer elsewhere in the body and a single brain metastasis.
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