When multiple sclerosis (MS) symptoms worsen from overheating, it’s called Uhthoff’s phenomenon. Learn more about prevention and treatment.
Some people with multiple sclerosis (MS) feel their symptoms worsen when they become overheated. When elevated body temperature impairs vision, it’s called Uhthoff’s phenomenon.
Uhthoff’s occurs because of damage to the optic nerve due to MS. It interferes with the transmission of signals between the eyes and the brain. Symptoms include blurry or reduced vision, and it’s often one of the first symptoms of MS.
Uhthoff’s phenomenon is sometimes called “Uhthoff’s syndrome” or “Uhthoff’s sign.” The condition was named for Wilhelm Uhthoff, a German professor of ophthalmology who lived from 1853 to 1927.
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Demyelinated fibers in the CNS are hypersensitive to a rise in body temperature. This makes it more difficult for the body to receive internal signals. This can result in a worsening of MS-related symptoms and cause blurred vision.
The good news is that heat sensitivity and the related worsening of MS symptoms are only temporary. This is called pseudo-exacerbation. It doesn’t mean new lesions, lasting neurological damage, or a more rapid progression of MS.
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