Answer: The worsening of symptoms in MS with heat or high temperature is called the Uhthoff phenomenon, also known as Uhthoff sign or Uhthoff syndrome. This decompensation is known for all demyelinating disorders. This can occur after exposure to hot weather, fever, hot shower, or exercise. Usual cooling methods are usually sufficient to resolve the symptoms.
Nystagmus and other visual disorders are particularly prone to worsen in patients with MS after increase body temperature. Prophylactic 4-aminopyridine may help to reduce sensitivity to visual impairments. This can be applied in ICU (like the patient in this question) or as an outpatient (like before exercise in MS patients).
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