Babinski Reflex Video:
The plantar reflex aka Babinski reflex is a reflex elicited when the sole of the foot is stimulated with a blunt instrument. The reflex can take one of two forms. In normal adults the plantar reflex causes a downward response of the hallux (flexion). An upward response (extension) of the hallux is known as Koch sign, Babinski response or Babinski sign, named after the neurologist Joseph Babinski. The presence of the Babinski sign can identify disease of the spinal cord and brain in adults, and also exists as a primitive reflex in infants.
The lateral side of the sole of the foot is rubbed with a blunt instrument or device so as not to cause pain, discomfort, or injury to the skin; the instrument is run from the heel along a curve to the toes (metatarsal pads). Many reflex hammers taper at the end of the handle to a point which was used for testing the plantar response in the past, however, due to the tightening of infection control regulation this is no longer recommended. Either a single use orange stick or the thumb nail should be used.
There are three responses possible:
- Flexor: the toes curve down and inwards, and the foot everts; this is the response seen in healthy adults.
- Indifferent: there is no response.
- Extensor: the hallux dorsiflexes, and the other toes fan out; this is Babinski’s sign, which indicates damage to the central nervous system.
As the lesion responsible for the sign expands, so does the area from which the afferent Babinski response may be elicited. The Babinski reflex is also normal while asleep and after a long period of walking.
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USMLE Step 2 CS Mnemonics: