Nerve dermatome: S1
Method (each foot tested separately):
(1) Select a dull instrument (edge of tongue blade, blunt end of reflex hammer, etc).
(2) Hold the ankle of the selected lower extremity firmly with one hand.
(3) Stroke the plantar surface of the foot with the dull instrument, starting at the lateral side of the heel, along the lateral side of the foot, then diagonally to the ball of the foot near the base of the great toe.
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Variation
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Difference
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Chaddock sign
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scratching with a dull point
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Oppenheim sign
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pressure over the anterior tibia
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Features of a complete Babinski sign ("positive"):
(1) dorsiflexion of the great toe (moves upwards and medial)
(2) fanning of toes 2 to 5
(3) dorsiflexion of the ankle (moves upwards)
(4) flexion of the knee and hip with withdrawal
A positive sign indicates involvement of upper motor neurons (often through involvement of the pyramidal tracts). The absence of one or more features indicates an incomplete Babinski sign.
Features of a "negative" Babinski sign (normal):
(1) plantar flexion of the toes
(2) plantar flexion of the foot
The absence of any flexion (neither plantar nor dorsal ) can be seen with loss of sensory or motor nerve supply, as in a peripheral neuropathy.
