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.
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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Article adapted by Medical
News Today from original press release.----------------------------
Other UT Southwestern researchers involved in the study were lead author
Scott Davis, assistant professor of neurology; Teresa Frohman, clinical research
manager in neurology; Dr. Craig Crandall, associate professor of internal
medicine; Douglas Mills, former research assistant; and Dr. Olaf Stüve,
assistant professor of neurology. A researcher from the New Jersey Neuroscience
Institute and a nurse from Presbyterian Hospital of Dallas also participated.
The work was supported by the National Multiple Sclerosis Society, Once
Upon A Time …, the Cain/Denius Comprehensive Center for Mobility Research, the
Sparrow Foundation, and the Hawn Foundation.
Click
here to learn more about UT Southwestern's clinical services in neurology.
Dr. Elliot Frohman Source: Aline McKenzie
UT Southwestern
Medical Center
