The Babinski reflex is a reflex response in the bottom part of the foot. It occurs as a reaction to stroking the sole of the foot with a blunt object.
The Babinski reflex is one part of the neurological testing that doctors use to check for healthy development or underlying neurological conditions.
Irregular reflex reactions may be a sign of an underlying neurological condition, which will require further testing for a diagnosis.
Keep reading to learn more.
The Babinski reflex, also called the Babinski sign or plantar reflex, is an automatic reflex in the foot in response to stimulation. Joseph Babinski, a French neurologist, first documented the reflex in 1896.
Testing for the Babinski reflex involves stroking the sole of the foot and assessing the response in the toes. If the Babinski reflex is present, the big toe will move upward as the other toes fan outward.
Although it took some time for the reflex to gain recognition, it is now one of the most important signs in clinical neurology. Doctors still use the Babinski reflex as a standard part of neurological testing.
The Babinski reflex is a marker for the health of the cortical spinal tract, which is a nerve channel sending information between the brain and the body and limbs. It is primarily responsible for motor control in the body and limbs.
The Babinski reflex is one type of standard check for neurological health. In very young children, a Babinski reflex is normal.
A study in the International Journal of Physiology found that the Babinski reflex occurs in about 62–75% of newborns. As newborns generally do not yet have a fully developed nervous system, the reflex is not necessarily a sign of a neurological condition.
While the reflex response is normal in infants, it should be absent after 24 months of age. In some cases, the reflex response disappears earlier — potentially as early as 1 year of age.
Doctors consider a Babinski reflex response that appears in adults or children over the age of 2 years to be an abnormal reflex response. It may be a sign of an underlying neurological condition or nervous system disorder.
In adults and children over the age of 2 years, the Babinski reflex may be a sign of an underlying central nervous system disorder or another issue in the cortical spinal tract.
Possible associated disorders include:
- spinal cord injury
- tumors in the spinal cord
- defects in the spinal cord or spinal column
- brain tumors
- multiple sclerosis (MS)
- Lou Gehrig disease
- cerebral palsy
As the reflex response is not a diagnosis in itself, anyone displaying an abnormal reflex response will still need additional testing so that doctors can diagnose the underlying cause.
To check for the Babinski reflex, a doctor will use a blunt object, such as a tongue depressor. Before the test, they will make sure that the person is in a relaxed and comfortable state. They may warn the person about the sensation of the test, which may vary from ticklish to uncomfortable and unpleasant.
The doctor will then firmly stroke the bottom of the foot with the object in a curved line, moving from the heel of the foot up toward the toes and over to the big toe. The standard response is automatic, causing the toes to flex down toward the pressure and stimulation. This normal response confirms that the Babinski reflex is absent.
The Babinski reflex occurs when the big toe extends up toward the top of the foot. Simultaneously, the other toes fan out away from each other. If this occurs in response to the test, it means that the Babinski reflex is present.
If nothing occurs and there is no response, this is a neutral result. The test, therefore, has no significance, and doctors will move to other methods of testing.
Doctors will also check for the sign in both feet. A reflex that is present in one foot and absent in the other can help show which side of the nervous system the underlying condition is affecting.
The Babinski reflex is not foolproof. False positives and negatives are possible with this test, especially if the technique is incorrect. For this reason, doing a Babinski reflex test in the home is not reliable.
Additional factors, such as someone having very ticklish feet, can also affect the test or make it difficult to complete correctly.
No matter the outcome of the test, doctors will still move on to other tests to continue their diagnosis. These may include other neurological tests or reflex, imaging, or blood tests.
The Babinski reflex occurs in response to someone passing a blunt object across the bottom of the foot from the heel to the big toe. When the reflex is present, the big toe flexes up, and the other toes spread out.
The reflex may be present in infants without any underlying conditions. After the age of 2 years, though, the Babinski reflex should be absent. A positive result in adults or children over the age of 2 years may be a sign of an underlying issue in the central nervous system.
False positives and negatives are possible with the Babinski reflex test, which is only one indicator. Doctors will still move on to other testing to help continue their diagnosis.
An annual general checkup for adults and children over the age of 2 years may include a Babinski reflex test, along with other reflex tests. Anyone uncertain about their results should see a doctor for a diagnosis.