The effects of induced hyperthermia on patients with multiple sclerosis.

Several authors have reported that induced hyperthermia causes new neurological signs to develop in patients with multiple sclerosis. Collins (1938) observed that a patient with multiple sclerosis while receiving fever therapy developed a series of neurological signs that reversed when the fever therapy was terminated. Simons (1937) pointed out that 62% of patients with multiple sclerosis gave a history of becoming weak when exposed to heat. Guthrie (1951) found that neurological signs can develop in a patient with multiple sclerosis when only a leg or arm is immersed in hot water, and he pointed out the frequent diminution in visual acuity and the appearance of scotomata when patients are totally or partially immersed in hot water. In an earlier study (Nelson, Jeffreys, and McDowell, 1958), we investigated the effects of induced hyperthermia by hot baths not only on patients with multiple sclerosis but on patients with a variety of other diseases of the nervous system. It was found that each of the 12 patients with multiple sclerosis developed neurological changes and that these were usually multiple (an average of 2-8 per patient). It was also found, however, that 550% of patients with diseases other than multiple sclerosis developed neurological changes. These were usually single signs and tended to occur at higher elevations of body temperature than in patients with multiple sclerosis. Patients with multiple sclerosis frequently developed alterations in extraocular movements, including the appearance of nystagmus, signs of dysfunction of the medial longitudinal fasciculus, and paralysis of extraocular muscles. Visual acuity also frequently decreased. It was found that three patients with multiple sclerosis developed signs before any elevation of body temperature was recorded. Because of the possibility that this may