Uhthoff ’s Phenomenon
Uhthoff ’s phenomenon (symptom) is the worsening of visual acuity ("amblyopia" in Uhthoff ’s 1890 description) with exercise in optic neuritis, reflecting the temperature sensitivity of demyelinated axons (i.e., reduced safety factor for faithful transmission of action potentials). The term has subsequently been applied to exercise and/or temperature related symptoms in other demyelinated pathways. It has also been described in the context of other optic nerve diseases, including Leber’s hereditary optic neuropathy, sarcoidosis and tumor.
Evidence suggesting that Uhthoff ’s phenomenon is associated with an increased incidence of recurrent optic neuritis, and may be a prognostic indicator for the development of multiple sclerosis, has been presented.
Inverse Uhthoff sign, improved vision with warming, has been described.
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Scholl GB, Song HS, Wray SH. Uhthoff ’s symptom in optic neuritis: relationship to magnetic resonance imaging and development of multiple sclerosis. Annals of Neurology 1991; 30: 180-184
Selhorst JB, Saul RF. Uhthoff and his symptom. Journal of Neuro-Ophthalmology 1995; 15: 63-69 (erratum: Journal of Neuro-Ophthalmology 1995; 15: 264)
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