Definition of Babinski sign
Babinski sign definition - medical term An important neurologic examination based upon what the
big toe does when the sole of the foot is stimulated. If the big toe goes up, that
may mean trouble.
The Babinski sign 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 sign.
The Babinski sign is manifest by the upturning of the big toe and also by fanning
of the other toes.
Most newborn babies are not neurologically mature so they normally show a Babinski
sign. 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 sign 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 sign -- 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 sign 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, response or phenomenon.
It is common but wrong to say that the Babinski sign 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 never be forgotten in medicine.
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