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TORONTO, CANADA. It is estimated that more than one per cent of all Americans
over 60 years of age suffer from Parkinson's disease (PD). There is no medical
cure for the disease and some of the drugs used to treat its symptoms (levo-
dopa) may ultimately speed its progression. This fact has rekindled the
interest in using brain surgery to stop the disease or at least ameliorate its
effects. Dr. Anthony Lang MD, a specialist in Parkinson's disease at the
University of Toronto, has just published an excellent review of the current
state-of-the-art surgery for PD. Dr. Lang warns that none of the surgical
procedures used for PD today have been exposed to rigorous, double-blind,
randomized clinical trials. Says Dr. Lang "As long as there are willing
neurologists and surgeons and desperate patients, this problem will persist
until the professional community decides to regulate the practice of its members
or until external regulations are imposed." He lists the example of adrenal
medullary transplantation which was quite popular for awhile, but which has now
been abandoned as useless and dangerous.
Surgery for PD can involve incisions (lesions) made in various parts of the
brain in an attempt to reduce tremors and other symptoms of the disease.
Thalamotomy has now been used for 40 years. It is somewhat effective in
reducing tremors, but can have serious side effects. Pallidotomy (surgery
involving the globus pallidus region of the basal ganglia) was reintroduced in
1992, but is still the subject of great controversy; as a matter of fact, there
is still no consensus as to where the incision should actually be made.
Pallidotomy may help with dyskinesias (involuntary muscle movements) caused by
leva-dopa, but its effects are short-lived (less than two years). Deep brain
stimulation (DBS) involves the implantation of electrodes in the thalamus or
globus pallidus areas of the brain. The electrodes are activated by an
electronic device (similar to a pacemaker) installed in the chest cavity. Some
preliminary results are promising, but again, there is no actual agreement as to
where the electrodes should be placed and the only reasonably valid trial of
this technique involved only 13 patients. Transplantation of human fetal tissue
into the brains of PD patients is an emerging approach. This procedure requires
the use of six to eight or more fetuses for each patient and, not surprisingly,
is fraught with controversy. It may provide some benefits in patients younger
than 60 years (none in patients older than 60 years) and can have serious side
effects. Dr. Lang concludes his review with the observation that "Despite
numerous claims, the evidence for benefit from surgical therapies in patients
with PD is relatively weak." NOTE: This study was partly funded by Medtronic,
Inc., a manufacturer of DBS equipment. [75 references]
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