Definition of Babinski response
< b>Babinski response: An important neurologic examination based upon what
the big toe does when the sole of the foot is stroked. If the big toe goes up, that
may mean trouble.
The Babinski response is obtained by stimulating the external portion (the outside)
of the sole. The examiner begins the stimulation back at the heel and goes forward
to the base of the toes. There are diverse ways to elicit the Babinski response.
A useful way that requires no special equipment is with firm pressure from the examiner's
thumb. Just stroke the sole firmly with the thumb from back to front along the outside
edge.
Too vigorous stimulation may cause withdrawal of the foot or toe, which can be
mistaken as a Babinski response.
The normal mature Babinski response also by fanning of the other toes.
Most newborn babies are not neurologically mature so they show a Babinski response.
Upon stimulation of the sole, they extend the great toe. Many young infants do this,
too, and it is perfectly normal. However, in time during infancy the Babinski response
vanishes and, under normal circumstances, should never return.
A Babinski response in an older child or adult is abnormal. It is a sign of a
problem in the central nervous system (CNS), most likely in a part of the CNS called
the pyramidal tract.
Asymmetry of the Babinski response -- when it is present on one side but not
the other -- is abnormal. It is a sign not merely of trouble but helps to lateralize
that trouble (tell which side of the CNS is involved).
The Babinski response is known by a number of other names: the plantar response
(because the sole is the plantar surface of the foot), the toe or big toe sign or
phenomenon, and the Babinski reflex, sign or phenomenon.
It is wrong to say that the Babinski response is positive or negative; it is
present or absent.
Babinski, despite the Slavic sound of the name, was French: Joseph Francois Felix
Babinski (1857-1932). His name will not soon be forgotten in medicine, thanks to
the reflex he described.
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