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Kernig’s Sign

What Is it, How It’s Used, and More

Author: Alyssa Haag

Editors: Ahaana Singh, Ian Mannarino, MD, MBA

Illustrator: Abbey Richard

Copyeditor: Joy Mapes


What is Kernig’s sign?

Kernig’s sign is a physical maneuver used to evaluate an individual for a suspected case of meningitis, a condition characterized by inflammation of the membranes (i.e., meninges) that surround the brain and spinal cord. Meningitis is typically caused by a viral infection, but it can also result from bacterial, parasitic, or fungal infections. Common symptoms of meningitis include a stiff neck and back; pain in the back, muscles, or neck; light sensitivity; and constitutional symptoms, such as a fever, nausea, vomiting, and headache. More severe symptoms include confusion and seizures.

A positive Kernig’s sign raises suspicion for meningitis. Still, further diagnostic testing, like a lumbar puncture, should be conducted in order to ensure a prompt and accurate diagnosis of meningitis.

How is Kernig’s sign performed?

Kernig’s sign is performed with the individual lying on their back with their hips and knees flexed and bent at a 90-degree angle. Next, the clinician will slowly extend and straighten one knee at a time. Resistance, pain, or an inability to extend the knee is indicative of a positive Kernig’s sign. Pain felt during this maneuver is usually experienced in the lower back. 

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Why does Kernig’s sign happen?

Kernig’s sign occurs as a result of meningeal inflammation caused by movement of the spinal cord or nerves against the meninges. Extension of the leg while performing Kernig’s sign stretches the hamstring, which pulls on the surrounding tissue near the inflamed spinal canal and meninges. This results in the inability to fully straighten a leg without pain or resistance when the hip is flexed at a 90-degree angle.

What are the most important facts to know about Kernig’s sign?

Kernig’s sign is an exam maneuver conducted when meningitis is suspected in an individual. Meningitis causes severe stiffness and inflammation around the brain and spinal cord. Kernig’s sign assesses for this stiffness and inflammation by stretching the hamstring muscle. Kernig’s sign is performed with the individual lying on their back with their hips and knees bent. The clinician will then slowly attempt to straighten the leg. If pain or resistance is felt, the Kernig’s sign is said to be positive. Further diagnostic testing is required in order to confirm the diagnosis of meningitis. 

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Related links

https://www.osmosis.org/learn/Meningitis
Neisseria meningitidis
Meningitis, encephalitis and brain abscesses: Clinical practice

Resources for research and reference

Kernig's sign. (n.d). In Physiopedia. Retrieved from https://www.physio-pedia.com/Kernig%27s_Sign 

Mayo Clinic staff. (2020, October 1). Meningitis. In Mayo Clinic: Health information, diseases & conditions A-Z. Retrieved February 1, 2021, from https://www.mayoclinic.org/diseases-conditions/meningitis/symptoms-causes/syc-20350508