The Babinski reflex is elicited by stimulating the lateral plantar aspect of the foot and normally causes plantar flexion of the toes. A positive Babinski sign, in which the big toe extends upward, suggests damage to the corticospinal tract in the brain or spinal cord. This allows abnormal spread of sensory input beyond the typical dermatome, causing the extension response. The presence of an intact Babinski reflex is normal in infants under 2 years old.

1. Babinski Reflex
• Described by the neurologist Joseph Babinski in 1896.
• Tests the integrity of the corticospinal tract (CST)
• Fibers from the CST synapse with the alpha motor neuron in the spinal cord and
help direct motor function.
• The CST is considered the upper motor neuron (UMN), and the alpha motor
neuron is considered the lower motor neuron (LMN).
• Damage anywhere along the CST can result in the presence of a Babinski sign.

2. • Stimulation of the lateral plantar aspect of the foot (S1 dermatome) normally leads to
plantar flexion of the toes (due to stimulation of the S1 myotome).
• The response results from nociceptive fibers in the S1 dermatome detecting the
stimulation.
• Nociceptive input travels up the tibial and sciatic nerve to the S1 region of the spine and
synapses with anterior horn cells.
• The motor response which leads to the plantar flexion is mediated through the S1 root
and tibial nerve.
• The toes curl down and inward.
• Sometimes there is no response to stimulation.
• This is called a neutral response. This response does not rule out pathology.

3. • Babinski sign occurs when stimulation of the lateral plantar aspect of the foot leads to
extension (dorsiflexion or upward movement) of the big toe (hallux).
• There may be fanning of the other toes.
• This suggests that there is been spread of the sensory input beyond the S1 myotome to
L4 and L5. An intact CST prevents such spread.
• In infants with CST, which is not fully myelinated, the presence of a Babinski sign in the
absence of other neurological deficits is considered normal up to 24 months of age.
• Babinski’s may be present when a patient is asleep

4. • Contraindication - lesion (such as an infection) in the affected area of the foot that
precludes the effective performance of the reflex
• Elicited by a dull, blunt instrument that does not cause pain or injury. Sharp objects
should be avoided. The dull point of a reflex hammer, a tongue depressor, or the edge of
a key is often utilized.
• The instrument is run up the lateral plantar side of the foot from the heel to the toes and
across the metatarsal pads to the base of the big toe.
• Variations - Chaddock (stimulating under lateral malleolus), Gordon (squeezing calf),
Oppenheim (applying pressure to the medial side of the tibia), and Throckmorton (hitting
the metatarsophalangeal joint of the big toe).
• The Hoffman reflex in the upper extremity - nearest equivalent of the Babinski sign