What is Kernig’s sign?
Kernig’s sign: A sign that indicates the presence of meningitis (inflammation of the meninges that line the brain and spinal cord). The Kernig sign test is performed by having the person lie on the back, flex the thigh so that it is at a right angle to the trunk, and fully extend the leg at the knee joint. If the leg cannot be fully extended due to pain, this is Kernig’s sign.
Kernig’s sign is used to diagnose meningitis.
To obtain the Kernig sign
Step 1. The patient is positioned supine with the hip and knee flexed to 90 degrees.
Step 2. Then the examiner slowly extends the knee (repeat with both legs)
Step 3. Resistance or pain and the inability to extend the patient’s knee more than 135 degrees due to pain bilaterally indicates a positive Kernig’s sign.
How to recognize Kernig’s sign?
Meningitis is a dangerous medical emergency characterized by inflammation of the membranes that border the spinal cord and brain.
Prompt diagnosis and treatment of meningitis are important to prevent further complications.
In 1882, a Russian physician named Vladimir Mikhailovich Kernig discovered that many people with meningitis could not extend their knees beyond a 90 ° angle without pain. This was called the Kernig sign.
However, more recent research shows that many people with meningitis do not have a Kernig sign. So, this is what you need to know:
How to find the Kernig sign?
To look for the Kernig sign:
- Lie on your back
- Bend your knee and hip at a 90 ° angle while another person slowly extends the knee
- If you feel resistance or pain, see a doctor immediately for treatment
- The patient is in a supine position
- The examiner flexes the hip and knee to 90 degrees
- Next, the examiner attempts to passively straighten the leg at the knee
- In a patient with a positive Kernig sign, the patient experiences pain along the spinal cord, and the pain limits passive knee extension
- Occurs when the patient does not “allow” the examiner to extend the knee of the elevated leg due to pain along the spinal cord
- Bilateral Kernig’s sign is more likely to imply meningitis
- Paresthesias can also be experienced in the hands and feet