Which statement describes the Uhthoff phenomenon in multiple sclerosis?

Which statement describes the Uhthoff phenomenon in multiple sclerosis?

• A. Symptom worsening with increased body temperature
• B. Symptom improvement with rest
• C. Symptoms due to dehydration
• D. Symptoms due to low blood pressure

Answer: (B)

The main idea here is that heat can temporarily worsen neurological symptoms in multiple sclerosis. When body temperature rises—due to fever, exercise, hot weather, or a hot bath—conduction in demyelinated nerves becomes less efficient, so existing MS symptoms (like vision changes, weakness, numbness, or fatigue) can become more noticeable. This effect is usually short-lived and improves again with cooling or rest as temperature returns to normal. That’s why the statement about symptoms worsening with increased body temperature best describes the Uhthoff phenomenon. Rest by itself isn’t what defines this phenomenon, and dehydration or low blood pressure describe other issues, not the specific heat-related conduction change seen in MS.

The main idea here is that heat can temporarily worsen neurological symptoms in multiple sclerosis. When body temperature rises—due to fever, exercise, hot weather, or a hot bath—conduction in demyelinated nerves becomes less efficient, so existing MS symptoms (like vision changes, weakness, numbness, or fatigue) can become more noticeable. This effect is usually short-lived and improves again with cooling or rest as temperature returns to normal. That’s why the statement about symptoms worsening with increased body temperature best describes the Uhthoff phenomenon. Rest by itself isn’t what defines this phenomenon, and dehydration or low blood pressure describe other issues, not the specific heat-related conduction change seen in MS.