A positive Babinski sign is best described by which plantar response?

A positive Babinski sign is best described by which plantar response?

• A. Flexion of the toes
• B. Dorsiflexion of the big toe with fanning of the toes
• C. No response
• D. Inversion of the foot

Answer: (B)

Stroking the sole triggers the plantar reflex, which in adults is normally a curling of the toes (flexion). A positive Babinski sign is the opposite: the big toe dorsiflexes and the other toes fan outward. This occurs because loss of corticospinal tract inhibition lets an adult’s plantar stimulus produce an extensor response, indicating an upper motor neuron lesion. The normal toe flexion is not a positive sign, so that option isn’t correct. No response isn’t typical for a Babinski sign, and inversion of the foot isn’t the characteristic plantar reflex pattern.

Stroking the sole triggers the plantar reflex, which in adults is normally a curling of the toes (flexion). A positive Babinski sign is the opposite: the big toe dorsiflexes and the other toes fan outward. This occurs because loss of corticospinal tract inhibition lets an adult’s plantar stimulus produce an extensor response, indicating an upper motor neuron lesion. The normal toe flexion is not a positive sign, so that option isn’t correct. No response isn’t typical for a Babinski sign, and inversion of the foot isn’t the characteristic plantar reflex pattern.