HOW TO ELICIT REFLEXES

You are seeing a patient for possible stroke, and find no reflexes, on either side, upper or lower limb. Does that mean you didn’t do it right?

 

First of all, finding absent reflexes bilaterally in at least one pair of muscles is quite common. It happens in up to half of the ankles of normal elderly patients.(McGee, Evidence-Based Physical Diagnosis) Of course, some neurology texts, such as DeJong’s, state that one should be able to obtain reflexes, and that 97% of reflexes are obtainable. Perhaps it varies with the population. I have seen neurologists go to great lengths to find occult reflexes, such as whacking the tendon really hard, or using 4 foot long collapsable reflex hammers.

 

In the ED, it is probably sufficient to apply a consistent strike and document findings.

 

MUSCLE STRETCH

The muscle should be extended enough that there is no slack, but not overextended.

 

KEEP THE WRISTS LOOSE

For the swing, let gravity do the work, and like golf, make sure you have follow through. When you swing hard there isn’t much bounce. Your arm and shoulder absorbs some of the effect. That is why I suggest letting gravity do the work. What I am really saying here is to let it bounce. Don’t cushion it at all. If you swing hard, sometimes you inadvertently cushion. If you have ever split firewood you will know what I mean. The hard grip is not as effective as the loose grip.

PATIENT MUST NOT HAVE MUSCLE TONE

The patient should be relaxed. If they have muscle tone it blunts the reflex

 

ACCENTUATION MANEUVERS

The Jendrassik maneuver of clasping hands and pulling apart can accentuate lower extremity reflexes. Clenching teeth accentuates upper extremity reflexes.

 

Take home points:

Extend the limb to remove slack

Let gravity do the swing

Use accentuation maneuvers (Jendrassik/teeth clench) when needed

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