Babinski
Formal Definition
The Babinski sign (plantar reflex): extension (dorsiflexion) of the great toe with fanning of the other toes in response to firm stimulation along the lateral plantar surface of the foot; abnormal (positive) in adults and indicates upper motor neuron (corticospinal tract) dysfunction.
How It's Used on the Ward
"Babinski is up" or "upgoing toes" or "positive Babinski" — a classic hard sign of CNS pathology, from stroke to spinal cord compression.
Example
""Patient presenting with acute paraplegia after falling from height: bilateral upgoing toes, absent rectal tone, sensation gone at T10 — cord injury at thoracic level until proven otherwise. Trauma surgery and neurosurgery both paged.""
Clinical Context
Normal in infants under 2 years (corticospinal tracts not yet myelinated). Abnormal in any adult: think cord compression, stroke, demyelination, TBI, meningitis, brain mass, ALS, hypoglycemia (metabolic encephalopathy). Elicited with a firm stroke from heel to ball of foot along the lateral sole using a key or tongue blade. False positives: ticklish patients, superficial stimulation. A neutral (no movement) response is not pathological — only extension is.