Plantar reflex

In medicine(neurology), the Babinski reflex or Babinski sign is a reflexthat can identify diseaseof the spinal cordand brain. It is more properly called the plantar reflex, as Babinski's sign in reality only refers to the pathological form.

Methods

The lateral side of the sole of the foot is rubbed with a sharp or hard implement (usually the tip of a tendon hammer), running from the heel along a curve to the metatarsal pads. It is an unpleasant sensation for most. There are roughly three responses possible:

• Flexor: the toes curve inwards and the foot pronates; this is the response seen in healthy adults. This is not a reflex; it is under voluntary control.
• Indifferent: there is no response (sometimes a feature of peripheral neuropathy).
• Extensor: the hallux (large toe) extends upwards, and the other toes to a lesser extent; this response is Babinski's sign.

In decerebratepatients, a more complex reflex is observed, which includes the lifting of the whole leg. This is a primitive reflex, indicating that the brainhas been damaged severely.

Interpretation

The extensor response can indicate damage of the spinal cordin the thoracal or lumbar region, or brain disease. Occasionally, a pathological plantar reflex is the first (and only) indication of a serious disease process, and a clearly abnormal plantar reflex often prompts detailed neurologicalinvestigations, including CT scanningof the brain or MRIof the spine, as well as lumbar puncturefor the study of cerebrospinal fluid.

Young babies (less than a few months of age) will also show an extensor response. A baby's smaller toes will fan out, and their big toe will dorsiflex slowly. This happens because the corticospinal pathways(that run from the braindown the spinal cord) are not fully myelinatedat this age, so the reflex is not inhibited by the cerebral cortex.

Relationship to Hoffmann sign

The Hoffmann sign, also known as the finger flexor reflex, is occasionally said to be the upper limbequivalent of the Babinski's sign because both indicate upper motor neurondysfunction. Mechanistically, they differ significantly; the finger flexor reflex is a simple monosynaptic spinal reflexinvolving the flexor digitorum profundusthat is normally fully inhibited by upper motor neurons. The pathway producing the plantar response is more complicated, and is certainly not monosynaptic. This difference has led some neurologists to reject strongly any analogies between the finger flexor reflex and the plantar response.

Eponym

The pathological reflex is named after Joseph Jules François Félix Babinski(1857-1932), a French neurologistof Polishdescent.

See also

• Hoffmann's sign
• Neurology
• Reflex action

External links

• Who Named Itdoctor/370da:Babinskirefleks

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This article is licensed under the GNU Free Documentation License.
It uses material from the http://en.wikipedia.org/wiki/Plantar+reflex Wikipedia article Plantar reflex.