Babinski Reflex (Plantar Reflex)

What is the Babinski sign?

The Babinski sign (reflex) is a reflex present when you stroke the bottom of your baby’s foot. Their big toe lifts and their other toes fan out.

Reflexes are involuntary muscle reactions to a stimulus. For the Babinski reflex, the stimulus is the physical movement of a finger or object along the bottom of the foot. Reflexes are automatic— you aren’t thinking about moving your muscles. Instead, your body reacts when something touches it in a certain way.

To understand the Babinski sign, it helps to understand how the reflex works. The Babinski’s sign can be seen in some babies as a response to the plantar reflex. The plantar reflex is one of the many tests that your baby’s physician might do as a part of the neurological examination to learn more about your child’s brain, nerve and spinal cord functioning.

The plantar reflex is performed by applying upward directed firm pressure to the sole of the foot. The test involves applying pressure from the heel, moving to the small toe and then sweeping to the big toe. The Babinki’s sign is said to be present when the plantar reflex causes the person’s big toe to go up while the rest of the toes fan outward.

The Babinki sign is normal in young babies but is abnormal in children older than 2 years of age or adults. When this reflex is present after age 2 or in adults, it indicates damage to your motor nervous system (brain and spinal cord).

Neurologist Joseph Babinski discovered the Babinski sign in 1896. The Babinski sign is also known as the extensor plantar reflex.

What causes the Babinski sign?

The corticospinal tract (CST) is a fibrous (white matter) pathway extending from your brain through your spinal cord. It helps you move. It’s an important structure that transmits motor (movement) commands originating in your brain that travels the length of your spinal cord.

Your physician evaluates the integrity of your CST by testing your plantar reflex, looking for the Babinski sign. Your baby’s physician will apply a firm pressure to the bottom of their foot. Nerve fibers send information to their spinal cord and brain along this pathway. Their brain responds by telling their foot to move.

Because the CST is immature in young children, the Babinski sign is present. But the CST matures as children grow. This causes the Babinski sign to disappear after two years.

What is the plantar grasp reflex?

The plantar grasp reflex is what replaces the Babinski reflex after age 2. When you gently place your finger below your baby’s toes, they’ll curl their toes down toward your finger. You’ll retain this reflex through adulthood. This is the normal response to the plantar reflex in this age group. It lets your provider know that your motor system is functioning as expected.

The main difference between the Babinski sign and the plantar grasp reflex is the direction of movement. It’s like turning a light switch on and off:

• Babinski sign: The toes fan out like flipping a light switch up to turn it on.
• Plantar grasp: The toes curl down like flipping a light switch off.

When does the Babinski sign disappear?

The Babinski sign usually disappears when your child turns 2 years old. It doesn’t always last until their second birthday — in some cases, your child may lose this reflex earlier, like within their first year.

When do adults have the Babinski sign?

If an adult has the Babinski sign, it indicates that there is damage to the part of their central nervous system (CNS) that controls movement (motor systems of the brain and spinal cord).

CNS conditions that cause the Babinski reflex after age 2 include:

• ALS (amyotrophic lateral sclerosis).
• Brain tumor.
• Meningitis.
• Multiple sclerosis.
• Neurodegenerative conditions like Alzheimer’s disease.
• Spinal cord injury.
• Stroke.

What is the plantar reflex test?

The plantar reflex test is a quick and painless test to verify if the Babinski sign is present. A pediatrician or neurologist may perform this test during a newborn examination or wellness visit in their first 2 years. A provider may also offer this test to adults with a suspected central nervous system condition during a neurological examination.

To perform this test, a provider will:

1. Ask you to remove you or your child’s shoes and socks and sit or lie down.
2. Use a dull instrument, like a tongue depressor or reflex hammer, and move it gently from your heel to the base of their big toe, in a sweeping manner.
3. They’ll watch for an upward movement (dorsiflexion) of the big toe and the other toes to fan out.

Other methods of testing the Babinski reflex are available if you or your child have fewer than five toes or other circumstances affecting your foot.

The reflex movement should happen immediately after your provider moves an instrument along your or your child’s foot. The outcome is either positive or negative.

What does a positive Babinski sign mean?

A positive Babinski sign means that during the plantar reflex test, your big toe lifted and your other toes spread out.

A positive Babinski sign is normal for children under 2 years of age. It’s abnormal for children older than 2 years or adults. It may be a sign of an underlying central nervous system condition.

What does a negative plantar reflex mean?

A negative plantar reflex means that your toes don’t respond at all during a plantar reflex test or they curl downward instead of up (plantar grasp reflex).

A negative plantar reflex test is normal after age 2. Some children lose this reflex and gain the plantar grasp reflex before age 2.

No movement may indicate that you or your child have a condition that affects how well your spinal cord sends messages to different parts of your body.