-----Original Message-----
From: Henry Buchtel [mailto:gusb@umich.edu]
Sent: Monday, September 13, 1999 8:44 PM
Subject: Re: Wada Test Details

--- snip ----

The "how" of the procedure depends on the medical center doing the test.
We do it as described on the web page you found. Basically, a
neuroradiologist places a thin tube in the person's femoral artery
(located in the groin region - local anesthesia is used so there is no
pain involved in placing the tube into this artery) and maneuvers it up to
one of the arteries in the neck (the internal carotid artery), where the
anesthesia will be injected. Most patients do not feel anything during the
maneuvering of the tube. Then a picture of the arrangement of the arteries
is made by injecting a substance into the arteries that is relatively
opaque to x-rays. The person gets some baseline language and memory tests,
and then the anesthesia is injected, which knocks out the functions of the
injected hemisphere for several minutes. The person's abilities during the
drug effect demonstrate the functions of the tissue in that part of the
brain.

The "why" in your mother's case has to do with the possibility that if the
surgery were done without regard to the functions of the brain involved in
the periphery of the tumor this could leave her without essential
functions, like speech or memory. The Wada test, by knocking out most of
the cerebral hemisphere in which the tumor is situated, can tell the
surgeon what might happen if functional tissue in or near the tumor is
removed (and the surgeon would want to know, at a minimum, if the
hemisphere involved is responsible for speech or not).

The risks of the test are more or less those of a cerebral angiogram
(which vary as a function of the person's age, medical history, and the
like), plus the additional (rare) allergy to the barbiturate used in the
test. The neuroradiologist will be able to tell you about this at the time
of the consent for the Wada test.

I hope this all goes well. Let me know if you have other questions.  --HB

H.A. Buchtel
U-M Departments of Psychiatry and Psychology and VAMC
http://www-personal.umich.edu/~gusb/