Babinski sign

Babinski sign (also known as the plantar reflex) is a reflex action in which the big toe moves upward or toward the top surface of the foot and the other toes fan out when the sole of the foot is stimulated. This response is normal in infants but abnormal in adults, where it indicates damage to the central nervous system, specifically the corticospinal tract.

History

The Babinski sign is named after the French neurologist Joseph Babinski, who first described the reflex in 1896. Babinski's work significantly contributed to the understanding of neurological disorders and the diagnostic process.

Physiology

The Babinski sign is elicited by stroking the lateral aspect of the sole of the foot with a blunt instrument. In infants, the upward movement of the big toe and fanning of the other toes is a normal response due to the incomplete myelination of the nervous system. In adults, however, the presence of the Babinski sign is indicative of an upper motor neuron lesion affecting the corticospinal tract.

Clinical Significance

The presence of the Babinski sign in adults is a critical diagnostic indicator of neurological conditions such as:

• Multiple sclerosis
• Amyotrophic lateral sclerosis
• Stroke
• Spinal cord injury
• Brain tumor

Related Reflexes

Other reflexes related to the Babinski sign include:

• Hoffmann's reflex
• Chaddock reflex
• Oppenheim's reflex

Diagnostic Procedure

To test for the Babinski sign, the patient should be in a relaxed position, either lying down or sitting. The examiner uses a blunt object to stroke the sole of the foot from the heel along the outer edge to the base of the toes. The response is observed and recorded.

Interpretation

• Positive Babinski sign: Upward movement of the big toe and fanning of the other toes, indicating a possible upper motor neuron lesion.
• Negative Babinski sign: Downward movement or no movement of the toes, which is the normal response in adults.

See Also

• Neurology
• Reflexes
• Upper motor neuron lesion
• Lower motor neuron lesion