Kernig's sign is indicative of which condition?

Kernig's sign is a clinical indicator often used in the diagnosis of meningitis, particularly when there is a suspicion of meningeal irritation or inflammation. This sign is tested by having the patient lie supine and flexing one of their legs at the knee and hip. If there is resistance to straightening the leg or if doing so causes pain in the lower back or neck, this is considered a positive Kernig's sign. The presence of this sign points toward irritation of the meninges, which is common in infections such as viral or bacterial meningitis.

While the other conditions listed may cause neurological symptoms, they do not specifically present with Kernig's sign. Stroke may present with varying motor deficits, concussion with altered mental status or headaches, and herniation could lead to distinct signs of increased intracranial pressure or abnormal posturing, but none of these conditions specifically correlate with a positive Kernig's sign as seen in meningitis. Thus, identifying Kernig's sign helps clinicians narrow down the differential diagnosis towards meningitis as a likely underlying cause.