DIAGN�STICO DE PARKINSON II
Maryse Schild, ass�dua colaboradora da Parkliste, ( http://www.parkliste.org/) enviou uma mensagem anexando uma outra de um participante (Hanz) que discute a quest�o do diagn�stico na DP, assunto objeto do blog do dia 4 �ltimo. � voz corrente que a DP s� se confirma na aut�psia, mas h� uma forte discuss�o sobre o emprego das t�cnicas de diagn�stico por imagem, as famosas �tomografias computadorizadas� (Tomografia computadorizada por emiss�o de p�sitrons - PET Scan). Apesar de considerar a hist�ria cl�nica e a sintomatologia do paciente como a parte principal de um diagn�stico de DP, Hans acaba admitindo que a tecnologia de imagem avan�ou e hoje, apesar do alto custo e de sua complexidade, pode ser uma ferrametna importante sobretudo para tirar d�vidas.
-----Mensagem Original-----
De: M.Schild
Enviado: ter�a-feira, 10 de setembro de 2002 08:42
Para: Parkliste
Assunto: Re:anxi�t� g�n�ralis�e et MP le bondiagnostique

Tout le monde peut se tromper, encore et encore. On dit que le Parkinson se
confirme a l'autopsie!
Sur la liste anglo, il y a en ce moment un mouvement pour demander un PET
scan ou un SPECT scan avec un reactif au Fluor dopa qui montre la
concentration de dopamine dans le cerveau dans les cas de diagnostic douteux.
Un membre de la liste a fait un bon resume de ce test. Je jpoins son message,
il est en anglias mais il y a maintenant plusieurs sites de traductions
Maryse




This is as I understand it, but of course this is also based upon the
opinions of some (IMO rather knowledgable) neurologists, and others may
(partly) disagree.

Parkinson's Disease is mainly diagnosed upon the story of the symptoms that
the patient tells to the doctor.
Only after death an autopsy can for certain confirm the diagnosis PD. In
about 15-20% of the cases investigated after death, the diagnosis is found
to have been something else than PD.

It is hard to diagnose PD, though symptoms appear to be clearly pointing in
that direction. It is even more difficult in the beginning and/or with
younger patients.

So the doctor looks for other ways to support the diagnosis PD. These
investigations do NOT diagnose PD either, but enlarge the probability of the
(in)correctness of the diagnosis.

Time is one of the factors. In time the symptoms get worse and support the
diagnosis.
Also a positive response to levodopa is support for a diagnosis of PD.
MRI is mainly used to exclude other illnesses like braintumors and other
anatomical disorders in the brain.

What then remains are the SPECT and PET scans. The main difference
between a SPECT and a PET scan is, that a PET scans the brain while the
patient is active, like walking on a treadmill or a making large movements.
SPECT scans the brain while the patient is in rest, like lying on his back.
Because of the more complicated technique the PET is (much) more expensive
and the SPECT is more commonly used and available. For (supporting) the PD
diagnosis SPECT is (almost) as good as a PET.

SPECT & PET scans can be used for two purposes, using different radioactive
agents called "tracers" (fluor-dopa and 1,2,3-Iodine are examples of
tracers):
1 is it PD or something like that or NOT (targetting the dopamine
concentrations).
2 is it PD or MSA (targetting the numbers of dopamine-receptors).

Note that also a PET or SPECT scan is not capable of definitely diagnosing
PD or MSA, it is only an enhancing tool for making the diagnosis (when
doubted after -several- visits to the neurologist considering symptoms and
progress) more (or less) probable. Some neurologists attach great importance
to a SPECT (or PET), while others do not find the results of a SPECT (or
PET) that significant. Research in the reliability of SPECT & PET scans are
not conclusive about that. In practice the results of a SPECT (or PET) scan
are either confirming or denying the doctors opinion, and accordingly the
further treatment is set out.

Besides the point that (only) a SPECT (or PET) is not able to give a
definite diagnosis, MONEY plays a major part in why they don't give every
suspected PWP a SPECT (or PET) scan. Waiting for a year and meanwhile
giving levodopa is much cheaper and (most of the time) as conclusive
regarding the correct diagnosis as a SPECT (or PET). Note also that in a
starting PWP the alterations in the substantia nigra are still very little
and not easy to interprete.

Problem cases (difficulty in diagnosis and/or treatment) after a few years
often DO get a SPECT (or PET) scan (probably not only for the patients, but
also for the doctors peace of mind). But problem cases often get second,
third or fourth, etc opinions with different doctors and they may (all) come
up with different diagnoses !! That can happen, because the main part of
diagnosis is still the story of the patient about his symptoms and the
interpretation of each doctor of those gathered data. Obvious is that the
patient gets very confused.

Hans.

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