Understanding Physical Exam Findings Associated With FND - Part 2

In part two of this four-part series, Casey Kozak discusses Hover's sign, the most well-known test for FND. 

Show transcript: 

Casey Kozak: 

Welcome back to Neurology Minute. My name is Casey Kozak with Rutgers, and today we're continuing our examination of functional neurological disorder. That is physical examination. This episode is dedicated to Hoover's sign, probably the most well-known test for FND, and in my humble opinion, one of the most confusing maneuvers to learn.

So today, we're going back to the origin using Dr. Charles Franklin Hoover's original description. Maybe you've heard of Hoover's Sign, but when do we use it? Hoover's sign is useful when a patient presents with one-sided lower extremity weakness, and FND is on the differential. Because the test relies on one healthy leg, you can't perform Hoover's test on a patient with total lower-body paralysis.

Now, how to perform Hoover's test. First, have the patient lie on their back and place their hand under the heel of the patient's weak leg. Then ask the patient to raise their strong leg off the plane of the bed. What do you expect to happen? Dr. Hoover made the astute observation that muscular resistance offered by the leg on the bed will be pressed onto the bed with the same force which is exhibited in lifting the strong leg off the bed. This is based on the principle that when one limb flexes, the contralateral limb extends. In this way, the leg on the bed acts as a sort of counterbalance to assist the action of raising the other leg.

Okay, but what does this mean for our examination? Well, if a patient's leg was paralyzed as the result of a stroke, for example, the patient would not be able to create that downward resistance. In a patient with functional leg weakness, however, this action is still possible. Therefore, Hoover's sign is present if the weak leg produces a downward force into the bed while the strong leg is lifted, which you will be able to feel as their heel pressing into your hand.

So to summarize, you're looking for a down pressure from the patient's weak leg when you ask them to raise their unaffected leg.

Time to break for some practice. Join us in our next episode when we'll look at some other helpful maneuvers for functional weakness.