ABSTRACT
In this chapter the author describes his experience and that of others in the use
of the Gamma Knife (Gamma Knife is a registered trademark of Elekta, Inc., Norcross,
GA, USA) radiosurgical instrument to make lesions in the ventral intermediate thalamic
nucleus to treat tremor of a variety of causes or in the internal segment of the globus
pallidus to treat rigidity, bradykinesia, and L-dopa-induced dyskinesias in Parkinsonian
patients. Patient selection for gamma knife procedures to treat movement disorders
is similar to that for radiofrequency thalamotomy or deep brain stimulation except
that patients of advanced age, those with other serious medical illnesses, and those
utilizing anticoagulants may be treated safely with the Gamma Knife. Between 85 and
90% of patients with Parkinsonian tremor or essential tremor are rendered either tremor-free
or nearly so following radiosurgical thalamotomy. These improvements are maintained
in patients who have been followed between 4 and 8 years after the procedures. About
50% of patients with tremors of other origins may be improved although complete freedom
from tremor has not been identified. Significant improvements in bradykinesia and
rigidity occur in Parkinsonian patients, particularly in the ``off'' state, following
radiosurgical pallidotomy. More than 85% of patients are rendered free of L-dopa-induced
dyskinesias following radiosurgical pallidotomy. These improvements are maintained
in patients followed more than 4 years after the procedures. Only 5 patients of more
than 300 treated (1.7%) developed any side effects from the procedures. Radiosurgical
thalamotomy and pallidotomy are effective and safe procedures for the treatment of
movement disorders. For patients who take chronic anticoagulants, they may be the
only form of surgical therapy available. Radiosurgical procedures are as effective
as radiofrequency procedures or deep brain stimulation procedures and should be considered
and presented as surgical options to patients who are surgical candidates for the
treatment of movement disorders.
KEYWORD
Radiosurgery - Parkinson's disease - essential tremor
