Plantar reflex

In medicine and neurology, the Babinski response to the plantar reflex is a reflex, named after Joseph Babinski (1857-1932), a Polish neurologist, that can identify disease of the spinal cord and brain and also exists as a primitive reflex in infants.^[1][2] When non-pathological, it is called the plantar reflex, while the term Babinski's sign (or Koch's sign) refers to its pathological form.

Methods

Babinski's Sign

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^[3] (metatarsal pads).

There are three responses possible:

• Flexor: the toes curve inward and the foot everts; this is the response seen in healthy adults (aka a "negative" Babinski)
• Indifferent: there is no response.
• Extensor: the hallux dorsiflexes and the other toes fan out – the "positive Babinski's sign" indicating 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 response is also normal while asleep and after a long period of walking.

Interpretation

Babinski's Sign in a healthy newborn

The Babinski’s sign can indicate upper motor neuron damage to the spinal cord in the thoracic or lumbar region, or brain disease – constituting damage to the corticospinal tract. 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 neurological investigations, including CT scanning of the brain or MRI of the spine, as well as lumbar puncture for the study of cerebrospinal fluid.

In infants

Infants 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 brain down the spinal cord are not fully myelinated at this age, so the reflex is not inhibited by the cerebral cortex. The extensor response disappears and gives way to the flexor response around 12-18 months of age.

Relationship to Hoffmann sign

The Hoffmann's sign is sometimes described as the upper limb equivalent of the Babinski's sign^[4] because both indicate upper motor neuron dysfunction. Mechanistically, they differ significantly; the finger flexor reflex is a simple monosynaptic spinal reflex involving the flexor digitorum profundus that is normally fully inhibited by upper motor neurons. The pathway producing the plantar response is more complicated, and is not monosynaptic. This difference has led some^[who?] neurologists to reject strongly any analogies between the finger flexor reflex and the plantar response.^{[citation needed]}

Babinski-like responses

The plantar reflex can be elicited in a number of ways, which were described in the late 19th and early 20th century. These have their own eponyms.^[5]

Abnormal reflex seen as extension of the big toe

• Bing's sign – multiple pinpricks on the dorsum of the foot
• Cornell's sign – scratching the dorsum of the foot
• Chaddock's sign – stroking the lateral malleolus
• Gonda's sign – flexing and suddenly releasing the 4th toe
• Gordon's sign – squeezing the calf muscle
• Moniz sign – forceful passive plantar flexion of the ankle
• Oppenheim's sign – applying pressure to the medial side of the tibia
• Schaefer's sign – squeezing the Achilles tendon
• Stransky's sign – vigorously abducting and suddenly releasing the little toe
• Strümpell's sign – patient attempts to flex the knee against resistance
• Throckmorton's reflex – percussion over the metatarsopahalangeal joint of the big toe

Abnormal reflex seen as flexion of toes

• Bekhterev-Mendel reflex – flexion of the 2nd to 5th toes on percussion of the dorsum of the foot
• Rossolimo's sign – exaggerated flexion of the toes induced by rapid percussion on the tips of the toes

Notes and references

1. ^ synd/366 at Who Named It?
2. ^ Comptes rendus de la Société de Biologie, 1896, volume 48, page 207.
3. ^ plantar reflex at Dorland's Medical Dictionary
4. ^ Harrop JS, Hanna A, Silva MT, Sharan A (2007). "Neurological manifestations of cervical spondylosis: an overview of signs, symptoms, and pathophysiology". Neurosurgery 60 (1 Supp1 1): S14–20. doi:10.1227/01.NEU.0000215380.71097.EC. PMID 17204875. 
5. ^ Kumar SP, Ramasubramanian D (December 2000). "The Babinski sign--a reappraisal". Neurol India 48 (4): 314–8. PMID 11146592. http://www.neurologyindia.com/article.asp?issn=0028-3886;year=2000;volume=48;issue=4;spage=314;epage=8;aulast=Kumar. Retrieved 2009-04-13. 

External links

• "Video of reflex on google video". http://video.google.com/videoplay?docid=-1862844561537172698.