Uhthoff's symptom is seen in:

Heat sensitivity refers to neurologic symptoms produced by an elevation of the body's core temperature. Uhthoff's symptom is the unilateral visual blurring that may occur during a hot shower or with physical exercise. It is also common in Multiple sclerosis. Such heat-related symptoms probably result from transient conduction block. Ref: Harrisons principles of internal medicine, 18th edition, Page: 3398.