Babinski reflex

Babinski Reflex

The Babinski reflex, also known as the plantar reflex, is a physical reflex that is observed in the foot. It is an important neurological examination tool used to assess the integrity of the central nervous system, particularly the corticospinal tract. The reflex is named after the French neurologist Joseph Babinski, who first described it in 1896.

Physiology

The Babinski reflex is elicited by stimulating the sole of the foot with a blunt instrument. The normal response in adults is plantar flexion of the toes, meaning the toes curl downward. However, in infants and in cases of neurological damage, the response may be dorsiflexion of the big toe and fanning of the other toes, which is considered a positive Babinski sign.

Developmental Aspects

In infants, a positive Babinski sign is normal and is due to the incomplete myelination of the corticospinal pathways. This reflex typically disappears by the age of 12 to 24 months as the nervous system matures. Persistence of the Babinski sign beyond this age may indicate neurological problems.

Clinical Significance

A positive Babinski sign in adults is considered abnormal and may indicate damage to the corticospinal tract. Conditions that may cause a positive Babinski sign include:

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

Examination Technique

To test for the Babinski reflex, the examiner uses a blunt object, such as the handle of a reflex hammer, to stroke the lateral aspect of the sole of the foot, starting from the heel and moving towards the toes. The examiner observes the movement of the toes in response to the stimulus.

Interpretation

• Normal response: Plantar flexion of the toes.
• Positive Babinski sign: Dorsiflexion of the big toe and fanning of the other toes.

Related Reflexes

The Babinski reflex is part of a group of reflexes known as the "primitive reflexes," which also include the Moro reflex, Palmar grasp reflex, and Rooting reflex. These reflexes are typically present in infants and disappear as the nervous system matures.

History

Joseph Babinski first described the reflex in 1896. His work laid the foundation for the use of the Babinski sign as a diagnostic tool in neurology. The reflex is sometimes referred to as the "Babinski sign" when it is used in a clinical context to indicate neurological dysfunction.

See Also

• Neurological examination
• Corticospinal tract
• Upper motor neuron lesion

References

• Babinski, J. (1896). "Sur le réflexe cutané plantaire dans certaines affections organiques du système nerveux central". Comptes Rendus Hebdomadaires des Séances et Mémoires de la Société de Biologie. 48: 207–208.
• Patten, J. (1996). Neurological Differential Diagnosis. Springer.