What Is Kernig’s Sign of Meningitis? Everything to Know

Medically Reviewed By Meredith Goodwin, MD, FAAFP
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Kernig’s sign is a diagnostic sign of meningitis. The Kernig’s sign test involves extending the knee to check for resistance that may be associated with meningitis. Named after Russian physician Vladimir Kernig, Kernig’s sign dates back to the 19th century. Kernig noted that individuals with bacterial or tuberculous meningitis could not completely extend their legs when sitting in an upright position.

Kernig concluded that pain or resistance when extending the knees beyond 135 degrees was a sign of meningitis. Experts believe that inflammation from meningitis causes this resistance.

This guide explains how to perform the test for Kernig’s sign of meningitis. This guide also discusses meningitis symptoms, when to contact a doctor, other diagnostic tests, and more.

How do I perform the Kernig’s sign test?

A clinician is holding a person's leg.
ALTO IMAGES/Stocksy United

To perform the Kernig’s sign test:

  1. Ensure that the individual is lying on their back.
  2. Position the hips so that they are flexed to 90 degrees.
  3. Extend the individual’s bent knee.

A positive Kernig’s sign is pain or resistance when you extend the individual’s knee.

Why is Kernig’s sign a diagnostic sign of meningitis?

Meningitis occurs when the meningeal layers in the brain become inflamed. The meningeal layers include the dura mater, arachnoid mater, and pia mater.

Meningitis causes the muscles in your lower limbs to become tight. You may also experience increased sensitivity in the nerves of your lower limbs. Stretching the inflamed, hypersensitive nerve roots during the Kernig’s sign test may cause the pain. The movement triggers a protective response. This response helps to prevent pain and spasms in your lower extremities.

What is a positive Kernig’s sign?

Pain upon passive extension of the knee is a positive Kernig’s sign.

If your Kernig’s sign test is positive, your doctor will arrange for other tests to assist with diagnosis.

When is Kernig’s sign not suitable?

Kernig’s sign can be a useful diagnostic sign of meningitis. However, in certain cases, it should be avoided.

Kernig’s sign may not be advisable for the following people:

  • infants with high muscle tone
  • infants who are tense
  • individuals with paraplegia, paralysis of the lower body
  • individuals who are comatose or very lethargic
  • individuals with hip, knee, or leg injuries

What are other signs and symptoms of meningitis?

Kernig’s sign is a diagnostic sign of meningitis. Your doctor may carry out the test if you experience other symptoms of meningitis, including:

You may not experience all symptoms of meningitis. Symptoms may also appear in any order.

When should I contact a doctor?

Contact your doctor or the child’s doctor as soon as you have concerns about meningitis.

Do not wait for a rash to appear. Not everyone with meningitis develops a rash.

Seek medical advice as soon as possible.

How do doctors diagnose meningitis?

Your doctor will not diagnose meningitis with the Kernig’s sign test alone. If Kernig’s sign is positive, your doctor may arrange for a CT scan and lumbar puncture. Learn about lumbar puncture.

Laboratory analysis of cerebrospinal fluid following lumbar puncture helps to determine the type of infection.

Find out more about how doctors test for and diagnose meningitis.

What is Brudzinski’s sign?

Like Kernig’s sign, Brudzinski’s sign may help in assessing an individual with suspected meningitis.

Brudzinski’s sign test involves the individual lying on their back while a medical professional flexes the individual’s neck. The test is positive if the hips and knees flex when the neck is flexed forward.

Limitations of Brudzinski’s sign include low sensitivity. The Brudzinski’s sign test alone is not suitable for diagnosing or ruling out meningitis.

Where can I learn more about meningitis?

See the links below for more information about meningitis.

Summary

Kernig’s sign is a diagnostic sign of meningitis. Pain upon passive extension of the knee may indicate that an individual has meningitis.

It is not possible to diagnose meningitis with Kernig’s sign alone. Your doctor may arrange for other tests including a CT scan and lumbar puncture.

Not everyone with meningitis will develop a rash. You should not wait for a rash to appear before seeking medical advice.

Contact a doctor as soon as you experience symptoms of meningitis or notice the symptoms in a child.

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Medical Reviewer: Meredith Goodwin, MD, FAAFP
Last Review Date: 2022 Aug 8
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THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.
  1. Karl, A., et al. (2022). Kernig sign. https://www.ncbi.nlm.nih.gov/books/NBK470365/
  2. Meningitis. (2019). https://www.nhs.uk/conditions/meningitis/
  3. Stribos, M. P., et al. (2022). Brudzinski sign. https://www.ncbi.nlm.nih.gov/books/NBK539911/
  4. Tracy, A., et al. (2020). How to use clinical signs of meningitis. https://ep.bmj.com/content/105/1/46.info