Kernig's sign is a test used in physical examination to look for evidence of
irritation of the meninges. The test involves flexing the thighs at the hip, and the knees, at 90 degree angles, and assessing whether subsequent extension of the knee is painful (leading to resistance), in which case it is deemed positive. This may indicate
subarachnoid haemorrhage
Subarachnoid hemorrhage (SAH) is bleeding into the subarachnoid space—the area between the arachnoid membrane and the pia mater surrounding the brain. Symptoms may include a severe headache of rapid onset, vomiting, decreased level of cons ...
or
meningitis
Meningitis is acute or chronic inflammation of the protective membranes covering the brain and spinal cord, collectively called the meninges. The most common symptoms are fever, headache, and neck stiffness. Other symptoms include confusion or ...
. Patients may also show
opisthotonus
Opisthotonus or opisthotonos (from grc, ὄπισθεν, translit=opisthen, lit=behind and grc, τόνος, translit=tonos, lit=tension, label=none) is a state of severe hyperextension and spasticity in which an individual's head, neck and spinal ...
—spasm of the whole body that leads to legs and head being bent back and body bowed forward.
Karl et al. noted much of the literature on Kernig's sign is old and they could find no randomised trials of it. They also noted low
Sensitivity of 5% meaning absence of Kernig's sign does not rule out meningitis, specificity however is 95% so if positive then meningitis is very likely. Kernig's should not be relied on when meningitis is suspected and a
Lumbar puncture
Lumbar puncture (LP), also known as a spinal tap, is a medical procedure in which a needle is inserted into the spinal canal, most commonly to collect cerebrospinal fluid (CSF) for diagnostic testing. The main reason for a lumbar puncture is to ...
should be performed.
Name
The test is named after
Woldemar Kernig
Woldemar Kernig, better known as Vladimir Mikhailovich Kernig ( lv, Voldemārs Kernigs; russian: Владимир Михайлович Керниг; 28 June 1840 – 18 April 1917) was a notable Russian and Baltic German internist and neurologis ...
(1840–1917), a Russian neurologist.
See also
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Brudziński's sign
Brudziński's sign or a Brudziński sign is any of three medical signs, all of which may occur in meningitis or meningism. All three are named after Józef Brudziński. In English, the name is often written without the diacritic (like many borrow ...
References
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Medical signs