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THE EFFECTS OF COLD ON POLIO SURVIVORS
Dr. Richard L. Bruno
Polio survivors are extremely sensitive to changes in temperature. At
merely cool temperatures, most polio survivors report that their feet have
always been cold to the touch, their skin a purplish color. However, as
polio survivors have aged, 50% report "intolerance to cold" and that their
limbs have become more sensitive to pain as the temperature decreases (Owen,
1985). Cold was reported to cause muscle weakness in 62% of polio
survivors, muscle pain in 60%, and fatigue in 39%. (Bruno & Frick, 1987).
When polio survivors were cooled in the laboratory from 86o F to 68o F,
motor nerves functioned as if they were at 50o F and polio survivors lost
75% of their hand muscle strength. (Bruno, et al., 1985a) But, although
polio survivors are twice as sensitive to pain as those without polio, no
increase in pain sensitivity was found at lower temperatures. (Bruno, et
al., 1985b)
The reason polio survivors have such trouble with cold is that the parts of
the central nervous system that should control body temperature were damaged
by the poliovirus. In the brain the hypothalamus (the "automatic computer"
that controls the inner bodily environment) was damaged by the poliovirus,
including the body's "thermostat" and the brain area that tells your blood
vessels to constrict. (Bodian, 1949) In the spinal cord, the nerves that
carry the message from the brain that tells the capillaries in the skin to
contract when it's cold were also killed by the poliovirus. (Bodian, 1949)
Thus, polio survivors are unable to stop warm blood from flowing to the
surface of the skin as the outside temperature drops. This allows loss of
heat from the blood near the surface of the skin and causes the limbs to
cool. When the limbs cool, arteries carrying blood to the skin and veins
that should carry blood out of the skin narrow passively as they get cold,
trapping blue venous blood in the capillaries and causing the feet to look
blue and to become even colder. The cold skin chills the motor nerves,
causing them to conduct more slowly and to be less efficient in making
muscles contract. The cold also chills tendons and ligaments (like putting
a rubber band in the freezer) making movement of weak muscles more
difficult. As polio survivors know, it takes hours under an electric
blanket or a long, hot bath to warm cold legs and regain strength.
However, when polio survivors take a hot bath, blood vessels do exactly the
opposite of what they do in the cold. Polio feet and legs become bright red
as arteries and veins relax and blood rushes to the skin. Then, when polio
survivors stand to get out of the tub, they can feel dizzy or even faint as
blood pools in their legs and causes their blood pressure to drop (see
Bruno, 1997). The pooling of blood in the feet also explains why polio
survivors' feet swell, swelling that increases as they get older. And polio
survivors' easily losing body heat explains why they have an increase in
symptoms, especially cold-induced muscle pain, as the seasons change.
Polio survivors need to dress as if it were 20o F colder than the outside
temperature. They need to dress in layers and wear heat retaining socks or
undergarments made of polypropylene (marketed as Gortex or Thinsulate) that
should be put on immediately after showering when the skin is warm. Polio
survivors need to remind doctors that EMGs or nerve conduction tests must be
performed in a room that is at least 75o F to prevent false abnormal
readings and that a heated blanket is necessary in the
recovery room after polio survivors have surgery (Bruno, 1996).
Dr. Richard L. Bruno is chairperson of the International Post-Polio Task Force and director of The Post-Polio Institute and The International Centre for Post-Polio Education and Research at Englewood (New Jersey) Hospital and Medical Center.
Bodian, D. (1949) Histopathological basis of clinical findings in
poliomyelitis. American Journal of Medicine, 6, 563-578.