Babinski Sign: What It Means and Why It’s Abnormal

All humans are born with reflexes — predictable, automatic movements your body makes in response to a stimulus, such as touch or cold. Some reflexes fade during infancy, while others remain throughout life.

Testing the Babinski reflex is one way clinicians can evaluate nervous system function.

The Babinski reflex is normal in babies and young children and usually disappears by age 2. The plantar reflex test is painless, though it may feel ticklish because it involves touching the bottom of the foot.

In this guide, we’ll cover what the Babinski sign is, how it’s tested, and what abnormal results can mean.

How the Babinski Sign Is Tested

Pediatricians and neurologists check for the Babinski sign with a simple plantar reflex test. To perform the test, the clinician asks you to remove your child’s shoes and socks and then runs a dull instrument, such as a reflex hammer or tongue depressor, along the sole of the foot. The clinician applies firm pressure, starting at the heel, moving along the outer side of the foot, and then sweeping toward the base of the big toe.

Because the response is automatic, the person being examined doesn’t need to follow instructions or deliberately move. This allows clinicians to use the test when someone can’t cooperate with other parts of a neurological exam. The Babinski reflex may still be present during sleep.

How the Babinski Sign Works

During a plantar reflex test, your child’s pediatrician or neurologist watches how the toes respond to pressure on the sole of the foot. A positive Babinski sign means the four smaller toes fan out while the big toe moves upward.

With a negative plantar reflex, the toes may not move or may curl downward rather than fan out. Downward curling is associated with the plantar grasp reflex.

When the Babinski Sign Should Be Present

A positive Babinski sign is generally normal in children under 2, although the reflex can disappear as early as 12 months, and some children develop the plantar grasp reflex before age 2. In children older than 2 and in adults, a positive Babinski sign is considered abnormal.

What Normal Test Results Show

The plantar reflex test helps clinicians assess a part of the central nervous system (CNS) that controls movement. The corticospinal tract (CST) is a bundle of nerve fibers that carries movement signals from the brain through the spinal cord.

In babies and young children, a Babinski sign within the expected age range reflects the immaturity of the CST. As the CST matures, the Babinski sign usually disappears.

When the Babinski Sign Is Abnormal

The Babinski sign is usually normal in babies and young children, and the exact age when it disappears can vary. In adults and children over 2, a positive Babinski sign is considered abnormal.

What Abnormal Results Mean

A positive Babinski sign after age 2 can indicate a problem involving the CST in the CNS. In adults and older children, a persistent Babinski sign may reflect damage to the motor pathways of the brain or spinal cord.

Some forms of ataxia can include Babinski signs. Tell your child’s pediatrician if your child has been diagnosed with ataxia or if you’re concerned about an unexpected Babinski response.

Conditions That Can Cause an Abnormal Babinski Sign

Multiple conditions affecting the CNS can cause a positive Babinski sign after age 2. Because the plantar reflex test is only one part of a neurological examination, an abnormal result doesn’t diagnose any one condition by itself.

Conditions in Children 2 and Under

If a child under 2 shows no toe movement during the plantar reflex test, it may suggest a problem with how the spinal cord sends messages to different parts of your body. However, age matters because the Babinski reflex may disappear as early as 12 months in children whose nervous systems are developing normally.

A foot infection or another lesion on the sole can make the standard plantar reflex test inappropriate or unreliable rather than changing the reflex itself. A clinician may inspect the foot and use another method to assess the response if needed.

Conditions in Older Children and Adults

If a child older than 2 still shows the Babinski sign or if the sign is present in an adult, the pediatrician or neurologist may evaluate for several conditions affecting the CNS. A Babinski sign after age 2 can be associated with:

• Multiple sclerosis
• Neurodegenerative diseases
• Meningitis (an infection of the membranes around the brain and spinal cord)
• A brain tumor
• Amyotrophic lateral sclerosis (ALS), also called Lou Gehrig’s disease
• Brain or spinal cord injuries
• Stroke
• Friedreich ataxia (an inherited ataxia that can include extensor plantar responses) along with other symptoms, such as vision or hearing loss
• Some rare inherited types of ataxia, including autosomal recessive spastic ataxia of Charlevoix-Saguenay

When To Talk to Your Child’s Doctor

If you’ve tried the plantar reflex test on your baby or young child and the response seems unusual for their age, let your child’s care team know.

Your child’s pediatrician can test the Babinski reflex in the office and interpret the response in the context of your child’s age and overall neurological exam. If needed, they may continue with other parts of a neurological exam to assess the brain, spinal cord, and nervous system.