surgeries

A brain operation shown to be helpful for many Parkinson's patients,especially those in late stages of the disease, is called pallidotomy. Doctors are not sure why the procedure works, but an October 1997 report in the
New England Journal of Medicine stated that half of the patients in a pallidotomy study at Toronto Hospital, who before the surgery needed help in eating, dressing, and personal hygiene, were able to resume these
activities independently. The study cautioned, however, that some of the surgery's effects diminished after two years and that the long-term effectiveness of the procedure still is unknown.

In pallidotomy, a surgeon makes a tiny hole in the skull and uses a tiny electric probe to destroy a small portion of the globus pallidus, which experts believe is overactive in Parkinson's patients. Before operating, the
surgeon has "mapped" the patient's brain with imaging techniques such as magnetic resonance and knows precisely where the probe should go. The patient is kept awake, but under sedation, so the surgeon can note
responses to stimuli. Though both sides of the brain have a globus pallidus,pallidotomies typically are performed on one side at a time. After the patient has recuperated, a second procedure is done if needed.

Thalamotomy is a neurosurgical procedure, first introduced in the 1950s for the treatment of Parkinson's type tremor, that selectively lesions a part of the ventrolateral thalamus. Patients with benign essential tremor and dystonia are also candidates for thalamotomy.This lesion relieves tremor of PD but it does not prevent the progression or alleviate the predominantly more incapacitating symptoms of akinesia, off phenomenon, postural instability or bradykinesia. The rationale for lesioning a particular nucleus, the Vim, of the ventrolateral thalamus is based on accumulated neurophysiological research and past surgical experience. The effect of Vim thalamotomy has been attributed to the interruption of the connection between the thalamus and the motor cortex.
Thalamotomy historically superseded pallidotomy. The first pallidotomies were attempted in the 1930s, but without the stereotactic frames in use since the 1950s. Obviously with the tools of the time, this type of neurosurgery was difficult and risky. The advent of levodopa therapy for PD in the 1960s caused a decline in
the use of neurosurgery as a treatment option.