Sunday, 20 November 2011

Babinski's sign

Level 1: The plantar or Babinski reflex is a 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 flexor or downward response of the big toe. 

An upward response (extension) of the hallux is known as Babinski response or Babinski sign, after Joseph Babinski (1857–1932), a French neurologist of Polish origin. 

The presence of the Babinski sign is indicative of an upper motor neurone lesion. 

A Babinski sign is normal in infants and typically disappears when they start walking. 

The following YouTube clip shows you how to perform a plantar response:

Please use the back of neurotip or disposable orange stick (originally made from wood of the orange tree) to test the plantar response. The use of a tendon hammer or other non-disposable item (keys) are discouraged in the modern era as they are a potential source of hospital acquired infections. 

"In my personal experience the plantar response is not a very good sign; i.e. when there are obvious upper motor neurone signs it tends to be positive and when the plantar response is equivocal the other supporting signs (tone, power and tendon reflexes) are also equivocal."

"I was once told that 'you haven't completed your training as a neurologist unless you can make the plantar response go up or down'; this sums up the clinical utility of the sign."

"In my experience a strikingly postive or exaggerated Babinski response is typically associated with demyelinating disease. However, many other upper motor neurone lesions can cause an exaggerated response."

"Babinski actually described extension of the toe whilst walking barefoot as being the sign; I am not sure of the modern derivation."

Level 3+: There are a lot of other signs that have been described that essentially mean the same as the Babinski reflex; the following is a partial list:
  1. Bing sign – multiple pinpricks on the dorsum of the foot
  2. Cornell sign – scratching along the inner side of the extensor hallucis longus tendon
  3. Chaddock sign – stroking the lateral malleolus
  4. Gorda sign – flexing and suddenly releasing the 4th toe
  5. Gordon sign – squeezing the calf muscle
  6. Moniz sign – forceful passive plantar flexion of the ankle
  7. Oppenheim sign – applying pressure to the medial side of the tibia
  8. Schaeffer sign – squeezing the Achilles tendon
  9. Stransky sign – vigorously abducting and suddenly releasing the little toe
  10. Strümpell sign – patient attempts to flex the knee against resistance
  11. Throckmorton reflex – percussion over the metatarsophalangeal joint of the big toe
For those of you interested in the history of neurology will find the following article of interest: Joseph Babinski.

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