Understanding the Plantar Reflex (or Babinski Sign)

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A question that comes up frequently in our EMT class is, “How do we assess distal motor function in altered or unconscious patients?” It’s a fair question. We usually drill our EMT students on checking that distal neuro function before and after c-spine immobilization. You remember the drill, “Can you squeeze my hands? Can you push down with your feet?” But how do we check motor function when the patient can’t or won’t respond to our requests?

One helpful assessment tool is the test for plantar flexion. This is sometimes referred to as the Babinski reflex although, the Babinski reflex is actually a little different than a simple plantar reflex. Both are useful to understand, so lets talk about them.

1) Plantar Reflex

If you’re ticklish on the bottom of your feet, you’re familiar with the Plantar reflex. That uncontrollable urge that some people have to move and jerk when an external stimuli is scraped up the bottom of their foot is rooted in the body’s plantar reflex. While this reflex can be illicited from both conscious and unconscious patients, it becomes particularly helpful in our unconscious subjects (when our other motor assessment options are limited).

To evaluate the plantar reflex, take a blunt, somewhat pointed object and run it up the medial aspect of the underside of the foot. (I prefer the business end of a pair of tightly closed trauma shears.) The movement should start at the heal and end up somewhere in the neighborhood of the little piggy that had roast beef…or even the little piggy that had none.

In the normal adult patient, the toes should point downward and inward and the foot should flex (point).

A strong plantar flexion movement indicates normal motor-neuro function in that leg. If the patient’s reflex is delayed, sluggish or absent, it should be noted for further examination. A sluggish plantar reflex may indicate neurological depression from sedation or an underlying disease process and an absent reflex may indicate some degree of neurological insult (head or spine injury).

One other abnormal finding that the caregiver should watch for is the extension of the toes (fanning out) and an extension of the top of the foot toward the head (dorsiflexion). This is an abnormal finding that is known as…

2) Babinski Sign

When the foot and toes abnormally extend upward toward the head during a plantar reflex assessment, this is called Babinski sign or Babinski reflex. It can be benign. Sleeping adults and children under two tend to have Babinski sign with no underlying pathology. But it is also present in head injury and some degrees of spinal cord injury.

If your patient has a suspected head or neck injury, checking for plantar reflex and noting the normal or abnormal results is certainly worth adding to your patient assessment toolbox.

Now it’s your turn: Do you use the plantar reflex assessment in your patient assessments? How well does it work? Leave us a comment and let us know.