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Updated: Jun 22, 2026

Comprehensive Autopsy Program for Individuals with Multiple Sclerosis
Published on: July 19, 2019
[Long-lasting and isolated Uhthoff's phenomenon after effort preceding multiple sclerosis]
A Fromont1, I Bénatru, L Gignoux
1Service de neurologie, hôpital Général, 3, rue du Faubourg-Raines, 21000 Dijon, France.
Introduction:
Described in 1890, Uhthoff's symptom corresponds to a transient blurred vision provoked by physical exercise or an increase of temperature. It is a frequent symptom occurring during the course of multiple sclerosis.
Patients And Method:
We report here four cases of patients presenting isolated Uhthoff phenomenon preceding multiple sclerosis by several years.
Results:
These four patients presented transient neurological symptoms induced by intensive sporting activity for 1 to 6 years before diagnosis of multiple sclerosis. These symptoms were often visual but sometimes motor or sensorial. All symptoms appeared above a certain threshold specific to each patient, after 15 to 30minutes of intense physical exercise (bike, running or handball) and all disappeared after a few minutes to one hour rest with full recovery to baseline.
Discussion:
Uhthoff's phenomenon is explained by a conduction block. It is due to axonal demyelization that provokes a reorganization of sodium channels induced by a decrease in a safety factor highly sensitive to temperature, or by release of soluble blocking substances (oxide nitric or cytokines).
Conclusion:
Without being specific, this symptom is strongly suggestive of this disease. Our case reports confirm the existence of "infraclinic multiple sclerosis".
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