Over time, the brains of multiple
sclerosis (MS) patients shrink, and in some patients the degree of shrinkage can
predict the worsening of symptoms, researchers report.
"Our major findings were that total brain (shrinkage) was significantly
greater in the patients with MS than in the (healthy) control subjects,"
according to Dr. Robert L. Grossman from the University of Pennsylvania in
Philadelphia, and associates.
The authors used sophisticated magnetic resonance imaging (MRI) software to
determine the percentage of area within the skull occupied by brain tissue (PBV,
a measure of brain atrophy or shrinkage) in 36 patients with MS and in 20
healthy individuals. The MS patients were retested over periods ranging from 1
to 7 years. The authors also compared the MRI results with disability scores
measured by the expanded disability status scale (EDSS).
At the outset of the study, the average PBV was significantly smaller in the
MS patients (85.5%) than in the controls (88.2%), the authors report.
There were no significant differences in any measure between the two types
of MS patients (27 patients with relapsing-remitting MS and 9 patients with
secondary progressive MS), according to the results.
The average PBV fell significantly over time for all patients (1.6% loss per
year), for patients with relapsing-remitting MS (1.5% loss per year), and for
patients with secondary progressive MS (2.0% loss per hear), the researchers
observe.
Only for the patients with secondary progressive MS, though, did EDSS scores
change in line with their brain shrinkage, the report indicates.
Even though they did not measure brain shrinkage in the control subjects
over time, the investigators explain, the average loss of brain tissue in MS
patients (about 18 mL or two-thirds of an ounce a year) appears to be nine times
greater than that seen with normal aging (0.7-2.0 mL per year), but less than
half that with Alzheimer's disease (40.0 mL per year).
Chronic, progressive brain shrinkage in patients with long-standing MS may
be a predictor of increasing disability, Grossman and colleagues conclude.
"Longitudinal (measurement) of brain volume loss in patients with MS may
therefore represent a sensitive and highly reproducible means of following and
predicting clinical response to drug therapy in MS treatment trials."
