Signs, Syndromes, and Phenomena: The Language of Neurological Disease

Multiple sclerosis distinguishes itself in many ways, not the least of which is its odd collection of physical reactions to the scraping, poking, hammering and prodding by our doctors during a neurologic exam. Lhermitte’s sign, Babinski response, and Uhthoff’s phenomenon are well-known terms. We might forget which is which sometimes, so here’s a reminder of what weird thing goes on where in the body when certain things happen.

Uhthoff’s Phenomenon occurs when a rise in body temperature causes MS symptoms to temporarily worsen. Worsened eyesight in those of us with optic neuritis is a very common manifestation, causing vision to blur or darken. Uhthoff’s belongs in the broader category of pseudo-exacerbation, which, by definition, imitates a relapse but isn’t a result of immune cells attacking myelin and will not cause lasting damage. More than 50 percent of MS patients experience Uhthoff’s Phenomenon when exposed to extreme heat and humidity. Others of us suffer a pseudo-exacerbation from the opposite temperature extreme, and some experience both.

Stress, both physical and emotional, is also a common cause of pseudo-exacerbations, often bringing on sudden and severe fatigue. Various medical conditions can also cause MS symptoms to worsen, including infections, thyroid abnormalities, allergies, and pain. A pseudo-exacerbation can involve sudden and dramatic worsening of foot-drop, balance, weakness, cognitive dysfunction, speech, hearing, vision, numbness, and spasticity. Although this worsening is temporary and does not damage the myelin, overheating in particular can be dangerous if the patient is driving or walking outside when suddenly stricken and loses her balance, coordination and/or vision. Moving into a cool environment will usually bring the patient’s symptoms back to baseline within an hour. As always, if you experience worsening symptoms that don’t resolve within 24-48 hours, you might be having an actual relapse and your neurologist should be notified.

Lhermitte’s Sign is a sensation that occurs when the head is bent forward, causing flexion of the neck. An electric shock feeling travels down arms or legs, or can be felt in the torso. A lesser known phenomenon is Reverse Lhermitte’s, where the same symptoms are brought on not by neck flexion, but its opposite, neck extension.

Some interesting trivia:

  • Though this phenomenon was named after French neurologist Jean Llermitte, he was not the one who discovered it. Neurologist Pierre Marie first described it in 1917 in connection with multiple sclerosis. In 1924, Llermitte published a paper on the phenomenon that happened to make it much more widely known and thus his name was forever attached to it. (That paper must have been a real page-turner even if the plot was a bit thin!)
  • Lhermitte’s Sign was formerly called barber chair phenomenon because the image of a man sitting in a chair and dropping his chin to his chest to have his hair cut illustrated the stance that brings on the sensation. Perhaps we could update it to salon chair phenomenon?

Babinski sign/reflex/response, also known as plantar reflex, occurs when the sole of the foot is stroked, causing the big toe to extend upwards and the other toes to spread out. The presence of this reflex in adults indicates nerve damage in the spine.

Finally, here’s a list of some interesting-sounding neurological terms you might not have heard before, most of which are associated with the symptoms of MS. Can you guess what they mean without reading the descriptions? Have you experienced any of these symptoms?

Clasp-knife response

Coital headache

Fried egg artifact

Ice cream headache

Ice pick headache


clasp knife: Spring-like resistance to passive extension at the elbow or flexion at the knee that increases up to a certain length and force before suddenly relaxing as the Golgi tendon organ is activated; sign of spasticity.

coital headache: Indomethacin-responsive headache disorder characterized by sudden, severe, throbbing, occipital headache that occurs just before or during orgasm .

fried egg artifact: Perinuclear halo around oligodendrocytes caused by formalin fixation artifact...characterized by weakness, ataxia, sensory loss, scoliosis, and cardiomyopathy.

ice cream headache: Nickname given to headaches that are cold induced; common in migraine.

ice-pick headache:Indomethacin-responsive headache disorder characterized by momentary, sharp, and/or jabbing pain that occurs either once or several times a day at irregular intervals.

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