Babinski sign
An abnormal plantar reflex indicating upper motor neuron dysfunction, characterized by dorsiflexion of the great toe.
Full Definition
The Babinski sign is a pathological reflex elicited by stroking the lateral aspect of the sole of the foot from heel to toe. In healthy adults, this stimulus normally causes plantar flexion of all toes (normal plantar reflex). When the Babinski sign is present, the great toe extends (dorsiflexes) and the other toes may fan out. This indicates dysfunction of the corticospinal tract (upper motor neuron lesion) and is normal only in infants under two years of age. The presence of a Babinski sign suggests lesions anywhere along the corticospinal pathway from the motor cortex to the spinal cord.
Usage
Usage note: Always specify unilateral or bilateral findings; normal in infants.
In Context
- "Bilateral Babinski signs were elicited, suggesting corticospinal tract involvement." — Neurological examination
- "The absence of a Babinski sign helped rule out upper motor neuron pathology." — Clinical documentation