Kernig

Kernig sign, also known as Kernig’s sign, is a clinical sign of meningeal irritation used in the assessment of suspected meningitis and related disorders. It is named after Vladimir Kernig, a Russian physician who described the sign in the late 19th century. While historically prominent, it is one of several bedside maneuvers rather than a definitive test.

To perform the examination, the patient lies supine. The clinician flexes the patient’s hip and knee to 90 degrees and then attempts to extend the knee. A positive Kernig sign is marked by resistance to extending the knee or by pain in the lower back and/or posterior thigh, sometimes accompanied by a hamstring spasm. The presence of a positive sign suggests meningeal irritation, which can occur with meningitis, subarachnoid hemorrhage, or other inflammatory or infectious processes affecting the meninges.

Nevertheless, Kernig’s sign is not specific or highly sensitive. False negatives occur, especially early in disease or in elderly or immunocompromised patients, and false positives can arise from musculoskeletal pathology or hip flexion limitations. It should be interpreted in the context of other findings, including the Brudzinski signs and clinical presentation, and confirmed with cerebrospinal fluid analysis when meningitis is suspected.

History and usage: Kernig sign remains part of traditional neurological examination, though modern practice increasingly relies on imaging and laboratory tests. See also Brudzinski sign for complementary meningeal irritation signs.