What Is Kernig’s Sign?

Kernig’s sign is a physical indication that meningitis may be present. It is one of the clinical signs used by healthcare providers to diagnose meningitis. Kernig’s sign is often looked for along with Brudzinski’s sign when someone is suspected of having meningitis. 

While a positive Kernig’s sign alone does not guarantee a meningitis diagnosis, it, along with a positive Brudzinski’s sign, increases the likelihood of a meningitis diagnosis. 

This article talks about what Kernig’s sign means, how it works, and why it is a significant clinical tool.

What Is Kernig's Sign?

Kernig’s sign is a clinical indication that meningitis may be present.

Kernig’s sign is named after neurologist and neurologist Vladimir Mikhailovich Kernig, who described the first signs of meningitis. He saw that many people with meningitis had problems with extending their legs due to spasms in the hamstring muscles. This physical symptom was named Kernig’s sign and was first published in medical literature in 1882.

Kernig’s sign is still used today as a way to assess the likelihood of meningitis.

How Does Kernig's Sign Work?

To check for Kernig’s sign, a healthcare provider will: 

1. Ask the patient to lie on their back and bring up their knees to a 90-degree angle, like a tabletop
2. Try to straighten the patient's legs one at a time 
3. Note a positive Kernig's sign if the muscles resist this extension of the leg or if there is pain in this movement

Kernig’s sign is often used with Brudzinski’s, another clinical sign of meningitis.

Brudzinski’s sign is noted when a person's knees and hips reflexively bend when their head is raised from the table while lying face up.

Why Is Kernig's Sign Important?

Looking for Kernig’s sign is simple and effective, which makes it a useful clinical tool to help diagnose meningitis.

While the presence of Kernig’s sign and Brudzinski’s sign alone doesn’t guarantee that meningitis is present, it provides enough justification to investigate further. Likewise, the absence of Kernig’s and Brudzinski’s signs is reassuring, but it does not totally exclude meningitis from the list of conditions that may be going on if someone has meningitis-like symptoms.

The bottom line is that Kernig’s sign, along with Brudzinski’s sign, increases the likelihood of a meningitis diagnosis, while the absence of these signs reduces the chances that meningitis is present.

When combined with a patient's medical history, other examinations, and diagnostic tests, Kernig’s sign contributes to a comprehensive diagnostic assessment for meningitis.

Many studies have evaluated the value and accuracy of clinical signs of meningitis, like Kernig’s sign. The results are mixed due to inconsistencies in standards used and low sample sizes, limiting these studies' findings.

Nonetheless, a 2019 study found that despite the variable findings of studies Kernig’s sign can be a useful clinical tool.

Summary

Kernig’s sign is a physical indicator used by healthcare providers to diagnose meningitis. Along with a positive Brudzinski’s sign, a positive Kernig’s sign increases the likelihood of a meningitis diagnosis. Testing for Kernig’s sign is a simple and effective way to help get to a meningitis diagnosis quickly so that treatment can be started sooner.

A Word From Verywell

Kernig’s sign is a useful tool to help a healthcare provider reach a meningitis diagnosis. However, it alone cannot detect meningitis. Rather, Kernig’s sign is a tool in a toolbox to help narrow down the causes when someone has meningitis-like symptoms.

As with any sort of diagnosis, Kernig’s sign should be considered alongside other clinical findings to ensure a comprehensive diagnosis.