bye,bye l-dopa? (fwd)

Stephen Black sblack at UBISHOPS.CA
Thu Aug 28 09:58:01 EST 1997


I just posted the following response to a query on my psychology list 
(TIPS). I'm re-posting it here for further comments from people with 
knowledge of this area, who are more likely to be on this list than on 
the psychology one.

-Stephen

On Tue, 26 Aug 1997, Michael Sylvester wrote:

> I can remember viewing footage of how individuals with Parkinson's
> disease would control their tremors by taking the drug l-dopa.
> Now medical researchers can perform operations on some of those
> individuals and apply a laser to some part of the brain and
> the tremors are virtually eliminated.
> In cases like this,what eventually becomes of the l-dopa treatment paradigm?
snip>

First, I'm surprised to hear that laser surgery is involved because the
structures involved are subcortical and unlikely to be accessible by
laser. But certainly there has been recent interest in using more
conventional means of destroying brain tissue (usually electrocoagulation,
I believe) to control Parkinson's. My impression, though, was that this
surgery (lesioning the globus pallidus or its projections to the thalamus)
eliminated only the tremors but not the akinesia (inability to initiate
movement). I did some browsing with that great resource, PubMed, and it
seems I was wrong. 

The abstracts of some recent papers (cited below) suggest that the surgery
is effective against all of the major symptoms of Parkinson's disease.
Curiously, not only lesioning seems to work, but the apparently opposite
procedure, brain stimulation, as well (Pahwa, 1997).  However, given the
risks asssociated with brain surgery, I would think that l-dopa or the
newer drugs now being introduced are going to continue to be the first
choice, with surgery kept as a last resort when they fail. 

-Stephen

Tasker, T. (1997). Pallidal and thalamic surgery for Parkinson's
  disease. Experimental Neurology, 144, 35-40.

Pahwa, R. et al (1997). High-frequency stimulation of the globus
  pallidus for the treatment of Parkinson's disease. Neurology, 
  49, 249-253.

Gilbert, M. et al (1996). Pallidotomy: a surgical intervention for
  control of Parkinson's disease. Journal of Neuroscience Nursing, 
  28, 215-216

Laitinen, L. (1995). Pallidotomy for Parkinson's disease. Neurosurgery
  Clinics of North America, 6, 105-112

Kopyov, K. et al (1997). Microelectrode-guided posteroventral medial
  radiofrequency pallidotomy for Parkinson's disease. Journal of
  Neurosurgery, 87, 52-59.


------------------------------------------------------------------------
Stephen Black, Ph.D.                      tel: (819) 822-9600 ext 2470
Department of Psychology                  fax: (819) 822-9661
Bishop's University                    e-mail: sblack at ubishops.ca
Lennoxville, Quebec               
J1M 1Z7                    Bishop's Department of Psychology web page at:                                                      
Canada                        http://www.ubishops.ca/ccc/div/soc/psy
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