The Hindu News Update Service
News Update Service
Friday, March 21, 2008 : 1600 Hrs
Sci. & Tech.
Eye test peers into heat-related multiple sclerosis symptoms
DALLAS: A bodysuit that heats or cools a patient, combined with painless
measurements of eye movements, is providing multiple sclerosis researchers at UT
Southwestern Medical Center with a new tool to study the mysterious link
between body temperature and severity of MS symptoms, according to Eurekalert,
the news service of the American Association for the Advancement of Science.
The researchers studied an aspect of MS called Uhthoff's phenomenon, named for
the German ophthalmologist who reported in 1889 that some people have temporary
vision problems after exercise or in hot weather. This and other symptoms of
MS, such as fatigue or problems with coordination, worsen in the heat for
most people with the disease.
Although doctors and researchers have long known about Uhthoff's phenomenon,
there has been no way to objectively measure its severity or how it is related
to body temperature.
The UT Southwestern study, available online and appearing in the March 25
edition of the journal Neurology, demonstrated that as body temperature rises,
the severity of an eye-movement disorder called INO, or internuclear
ophthalmoparesis, also increases. When a person with INO looks rapidly from one
object
to another, one eye moves more slowly than the other. Normally, the eyes move
at the same speed.
INO can serve as an easy-to-measure "canary in a coal mine," acting as a
surrogate for other heat-related symptoms that are harder to measure, such as
fatigue,
mental confusion or bladder or bowel problems, said Dr. Elliot Frohman,
professor of neurology and ophthalmology, director of the Multiple Sclerosis
Program
and Multiple Sclerosis Clinical Center at UT Southwestern and senior author of
the study.
The researchers' tools were a whole-body suit, riddled with tubes for
circulation of water, that can change body temperature; a pill-like thermometer
that
measures core body temperature after being swallowed; and an infrared camera
that painlessly tracks eye movements.
The study, conducted at UT Southwestern, included eight patients with MS who
have INO, eight with MS but not INO, and eight healthy control subjects. Warm
water in the body garment raised each subject's normal temperature by one-half
of a degree Celsius, and the cool water brought it down by one-half of a
degree.
The subjects also wore a lightweight device, fitted on a headband, that used
infrared light to track their eye movements as they followed a random sequence
of blinking lights.
In the subjects with INO, increasing the body temperature worsened the
differences between their two eyes' relative motion. Conversely, cooling the
body
made the eyes synchronize better.
Monitoring INO in a clinical setting could provide a sensitive test to
determine a patient's susceptibility to other heat-related MS symptoms, as well
as
a way to monitor the effectiveness of treatments, Dr. Frohman said.
"With this new technique, we can objectively test new therapies that
specifically treat a host of MS-related symptoms," said Dr. Frohman.
The next step in the research, Dr. Frohman said, is to use this system to
measure the effectiveness of a drug that appears to relieve heat-induced
symptoms
in people with MS.
"We've shown that by this method we can model the principal mechanisms that
cause certain symptoms to worsen in people with MS," he said.
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