Definition of Kernig sign

Kernig sign: A sign indicating the presence of meningitis (inflammation of the meninges covering the brain and spinal cord). The test for Kernig sign is done by having the person lie flat on the back, flex the thigh so that it is at a right angle to the trunk, and completely extend the leg at the knee joint. If the leg cannot be completely extended due to pain, this is Kernig sign.

Source: MedTerms™ Medical Dictionary
http://www.medterms.com/script/main/art.asp?articlekey=7305
Last Editorial Review: 3/19/2012