What condition does a positive Kernig's sign indicate?

A positive Kernig's sign is indicative of meningeal irritation, which is most commonly associated with meningitis. This clinical sign is elicited when the patient is lying supine, and the examiner flexes the patient's hip and knee to 90 degrees, followed by an attempt to extend the knee. A positive response occurs if this extension causes pain in the back or neck, suggesting irritation of the meninges.

Meningitis can be caused by infections (such as viral, bacterial, or fungal) that lead to inflammation of the protective membranes covering the brain and spinal cord. The presence of a positive Kernig's sign, in conjunction with other clinical findings such as rigidity and fever, assists healthcare providers in making a diagnosis of meningitis. Understanding this sign's relevance highlights the underlying pathology of meningitis and differentiates it from other neurological conditions which may not exhibit such specific signs of meningeal irritation.