On Sunday August 23, the Cleveland Clinic Foundation sponsored a
symposium, "New Discoveries: Parkinson's Disease and Tremor Disorders".
Speakers from the Cleveland Clinic included: Gene H Barnett, M.D., Vice
Chairman, Department of Neurosurgery; R. Stanley Burns, M.D., Director,
Movement Disorders Program; and Erwin B. Montgomery, M.D., Director of
Research, Movement Disorders Program. Ray Watts, M.D., Associate Professor,
Department of Neurology at Emory University School of Medicine, also spoke.
(William C. Koller, M.D., Ph.D., of the University of Kansas Medical Center,
scheduled to speak, was unable to appear.) Each spoke for about 20 minutes
and a question and answer period followed.
Dr. Montgomery, in his opening remarks, noted that a research project
concerning the genetic factor in Parkinson's Disease will be conducted at
the Clinic. To aid in this project, the Clinic is seeking as participants,
families in which more than one member has Parkinson's Disease. Anyone
meeting this criterion is urged to contact the Cleveland Clinic Movement
Disorders Program, Department of Neurology, at 216-445-1108, or call the
Clinic at 1-800-223-2273.
Dr. Burns, speaking on New Medications for Parkinson's Disease,
centered his remarks on Mirapex, Requip, and Tasmar, all introduced within
the last year or so. He explained that Mirapex, which he described as "the
simplest of the drugs to use", produces the effect of dopamine, but is a
synthetic agent, as opposed to levadopa (Sinemet), a natural chemical. Dr.
Burns noted that Mirapex is a long-acting drug which complements Sinemet in
aiding tremor, balance, and postural problems, but also has some unique
properties, providing both anti-depressant and anti-fatigue effects. He
remarked that the "down side" of the drug is its capacity to cause
confusion, hallucinations, psychosis and paranoia in some patients, and
noted that, for these reasons, its use should be monitored.
Dr. Burns characterized Requip as a "sister to Mirapex", with the
distinction of more difficulty in adjusting dosage, but less likelihood of
producing side effects.
Tasmar was described by Burns as a complex drug with no intrinsic
anti-Parkinson's Disease activity. By itself, Tasmar will do nothing, he
noted; Tasmar must be used in combination with Sinemet. As the newest drug,
learning how to adjust dosage is key , and it will take longer to optimize
its effect. Tasmar's primary benefit is decreasing fluctuations (on/off
periods); its primary challenge will be refinement in its use.
Dr. Burns commented on new drugs now in the laboratory stage, noting
that the goal is to improve the function of dopamine-producing cells still
intact and to reduce the rate of progression of the disease.
Dr. Barnett, speaking on Surgical Options for Movement Disorders,
stated that surgery for Parkinson's Disease was not new, but was popular in
the '50's and '60's, with thalamotomy being the most used, but then
abandoned. In l992, the surgical treatment, pallidotomy, was developed, and
interest in fetal transplant of dopamine-producing cells increased. In
1997, the deep brain stimulation procedure was approved by the FDA.
Presently, thalamotomy is the procedure preferred for control of
tremor. Pallidotomy, which destroys selected cells in the thalamus, globus
pallidum, and sub-thalamic nucleus which have become hyper-active due to the
death of cells in the substantia nigra, is more effective for other symptoms
such as dyskinesea.
The newest development, deep brain stimulation (DBS), implants electrodes in
the brain, connected to a pacemaker located under the clavicle.
Dr. Barnett distinguished DBS from the pallidotomy procedure by noting
that the gamma knife, used in the pallidotomy, is "often but not always"
perfect, and involves destruction of cells, whereas DBS is both adjustable
and reversible.
Dr. Ray Watts, discussing the future of surgery for Parkinson's
Disease, explained that the fundamental problem is the death of
dopamine-producing cells, and that the goal is to stop progression of the
loss of such cells and, ideally, to restore their function.
Early Swedish experiments in transplanting human fetal
dopamine-producing cells found the area of the brain which develops dopamine
was increased, to the extent that some patients no longer needed to take
Sinemet. However, in the US, use of human cells has been controversial.
Further, the need for an infinite supply of brain cells for transplantation
cannot at this time be met.
Presently, controlled trials of the use of pig fetal cells have shown
that porcine cells are, at best, as good as human cells for this purpose.
Dr. Montgomery, in distinguishing Essential Tremor (ET) from
Parkinson's Disease, explained that ET tends to involve tremors of the head
and is familial, unlike Parkinson's. He noted that, though ET is more
common than Parkinson's, research in development of new treatments for ET
has lagged, because no animal model is available; scientists have been
unable to produce ET in animals. Dr. Montgomery remarked that, though a
number of medications have been used to treat ET, none has been effective
for more than a small percentage of patients, and side effects preclude
their use for many. However, both Thalamotomy and DBS have proved to be
useful surgical treatments for ET.
Another movement disorder, Multiple Sclerosis, also involves tremor in
approximately 15-20% of patients. Dr. Montgomery, while noting that the
prognosis for MS is much better now than previously, explained that surgical
interventions are not as successful for MS, since physicians are reluctant
to destroy the thalamus, and adjustments of DBS are necessary repeatedly for
MS patients.
In general, Dr. Montgomery noted that the pace of developments in
treatment of movement disorders is now so rapid that regulatory agencies
can't keep up with it; the FDA is years behind, in many instances.
It was notable that each of the speakers was "upbeat" and optimistic about
the future.
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Sid Roberts 68/3 <[log in to unmask] > Youngstown, Ohio
