Kernig’s test and Brudzinski’s sign

Definition:
Kernig’s test and Brudzinski’s sign are clinical tests used to assess the integrity and inherent tension residing within the spinal cord and it’s meningeses. These tests are often performed to assess a patient suspected to have meningitis and other spino-cerebellar lesions capable of affecting the spinal cord.

Test procedure:
Kenig’s sign:
1. The patient lies supine.
2. The hip and knee is flexed by the examiner up to 90 degrees..
3. The examiner then attempts to passively straighten the leg at the knee.
4. In a patient with a positive Kernig’s sign, the patient experiences pain along the spinal cord and the pain limits passive extension of the knee.

Brudzinki’s sign
1. The patient lies supine in extension.
2. The examiner gently grasps the patients head in the occipital lobe region and attempts flexion of the neck.
3. Brudzinski’s sign occurs when flexion of the neck causes involuntary flexion of the knee and hip (an attempt by the patient to lessen the stretching of the inflamed meninges).

Although Kernig’s and Brudzinski’s signs are both commonly used to screen for meningitis, the sensitivity of these tests is limited.

Test findings:
Kernig’s Sign
1. Occurs when the patient does not ‘allow’ the examiner to extend the knee of the elevated leg due to pain along the spinal cord.
2. Bilateral Kernig’s sign is more likely to implicate meningitis.
3. Paraesthesiae may also be experienced in the hands and feet.

Brudzinki’s Sign
1. Neck stiffness upon test movement causes the involuntary flexion of the knee & hip.
2. The patient experiences pain along the cervical spine and thoracic spine.
3. Paraesthesiae may also be experienced in the hands and feet.

Considerations:
These tests are used to assess for any sign of meningeal irritation. Any inability to incomplete the test movement due to pain or discomfort may be linked to spinocerebellar lesions. These tests are not highly sensitive, further investigations are often needed. Exclude local spinal pathologies such as myelopathies and prolapsed intervertebral disks.