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· Subject: Ischemic brain seen in chronic fatigue patients
Sorry about the delay in posting this.
A couple of definitions are included for all those like me who didn't know what
the terms were.
-------
Perfusion - force a fluid through an organ especially by way of
the blood vessels.
Ischemic - localized anemia due to obstruction of the inflow of
arterial bloood.
133Xe rCBF - the 133 is a superscript
99mTc-HMPAO - the 99 is a superscript
---------------------------------------------------------------------
Ischemic brain seen in chronic fatigue patients
The Medical Post, January 19, 1993
Toronto - Patients suffering from chronic fatigue syndrome (CFS)
do so because of cerebral function abnormalities as a result of
diminution of brain blood flow, says a California nuclear
medicine specialist.
Dr. Ismael Mena of the Harbor-UCLA Center in Los Angeles said:
"All adult patients with chronic fatigue have abnormal diminution
of blood flow to different areas of the brain - mostly in the
frontal lobes."
He told a meeting on CFS held here recently that this diminished
blood flow could reflect damage to those areas, but might also be
the result of damage to another area of the brain that is
expressed in the frontal lobes.
He said the primary damage bay be in the limbic system,
particularly in the hippocampus. "This is the one that projects
directly in the frontal lobes where most of the damage is seen in
patients with chronic fatigue."
The diminutions of blood flow to the temporal lobes could also
explain why patients with chronic fatigue complain of cognitive
impairment as that is where the memory resides.
Using brain Single Photon Emission Computer Tomography (SPECT),
Dr. Mena studied the brain flow patterns of 19 normal people with
an average age of 66; 33 CFS patients with an average age of 55;
and 26 patients with depression and a mean age of 62.
Great Precision
Although computed tomography (CT) and magnetic resonance imaging
(MRI) can denote with great precision the structures of the
brain, with brain SPECT the functions of the brain can be
examined. Dr. Mena said he examined the brain blood flow because
it is directly related to brain function.
Two sets of measurements were taken - one using 133Xe rCBF to
measure the amount of blood flow in the brain tissue, the other,
99mTc-HMPAO, to provide images of the brain blood flow.
Dr. Mena said in a normal person the blood flow, when measured
using 133Xe rCBF, fluctuates between 50 and 67 mL/min/100g of
brain tissue.
However, patients with CFS don't exhibit a uniformity in blood
flow.
For example, in one patient, aged 42, blood flow was 37
mL/min/100g in the right frontal lobe.
"For a person of this age it should be 55, +/-5," he said.
In another example, a 48 year-old woman, there was extensive
hypoperfusion in the frontal lobes. "But more extensively in the
dorsal frontal lobes with blood flow between 38 mL and 47 mL," he
said.
The 99Tc-HMPAO data also showed patients had both frontal
perfusion and temporal hypoperfusion, but to provide a more
precise analysis of the data, Dr. Mena said regions of interest
were set and a computer was used to calculate the mount of blood
flowing in them. Approximately 100 measurements were taken per
patient.
Dr. Mena said when this type of analysis was done, the
distribution of 133Xe rCBF in a normal elderly person is close to
45 mL/min/100g.
Again, this data showed in patients with CFS there was diminution
of blood flow in the right hemisphere. With the 99mTc-HMPAO
data, Dr. Mena said there was significant hypoperfusion
throughout the frontal lobes as well as the right temporal lobe.
Dr. Mena also examined the effect of exercise on patients with
CFS. Patients were given the standard cardiac stress test.
While a normal person usually gets his wind back within five
minutes after doing the test, those with CFS had to wait at least
one hour before their levels of carbon dioxide returned to their
pre-exercise levels.
"There's a marked worsening of blood flow in both hemispheres,
but mostly in the right hemisphere, and these abnormalities
persist up to 24 hours," he said.
After 24 hours, sometimes even 48 hours, patient's brain blood
flow returned to where it was at normal activity level.
=========================================================================
· Subject: Ischemic brain seen in chronic fatigue patients
> If I read this correctly, they're saying that brain blood flow gets worse afte
> exercise. Is this really what the article said?
>
> ++PLS
I'm not sure I understood everything that was described, particularly
with regard to what carbon dioxide levels are supposed to do normally
vs. in CFS patients, but my interpretation of what was described is that
if patients are exercised beyond their tolerable level of stress, then
Dr. Mena's study shows a lowered circulation of blood in the brain.
The article didn't refer to "beyond their tolerable level of stress",
I'm just reading that into it.
Thanks once again to Barry Drodge, who has previously provided us with
news about CFS. And I welcome Matt Straznitskas to CFS-L. Matt has
been active on the Fiodnet CFS Echo, especially in promoting an exchange
of newsletter material by CFS groups on the echo.
Roger Burns bfu@cu.nih.gov / bfu@nihcu.bitnet / fidonet 1:279/14
List-owner, Chronic Fatigue Syndrome discussion
CFS-L on LISTSERV at NIHLIST.BITNET or LIST.NIH.GOV
Newsgroup: alt.med.cfs
=========================================================================