Plantar reflex / Babinski sign

Definition:
The Babinksi response to the plantar reflex is a test which can identify pathological processes affecting the spinal cord and brain, and that also exists as a primitive reflex in neonates. The superficial plantar reflex also evaluates the integrity of a reflex arc involving the L5 and S1 spinal segments.

Test procedure:
Perform the test with the patient supine, and explain to them what you are going to do. Use a pointed but blunt object such as the handle of a reflex hammer or the handle end of a throat swab stick. Holding the foot steady, draw a line on the sole of the foot up the lateral border and across the pad, watching the toes for movement. If patient withdraws their foot, the pressure may be too light or too heavy.

Test findings:
A normal plantar reflex response involves toe flexion, or even no movement. A positive test, also known as a Babinski sign, involves the hallux extending with all other toes flexing and / or spreading. A positive response is associated with an upper motor neurone lesion. Note that a Babinski response is normal in children under 2 years old.

Considerations:
The plantar surface can be very sensitive: ensure that a withdrawal response involving knee and hip flexion is not mistaken for the reflex itself.