Kernig's sign is a test for irritation of which structure?

Kernig's sign is a test for irritation of which structure?

• A. Meninges
• B. Brain parenchyma
• C. Peripheral nerves
• D. Cerebellum

Answer: (A)

Kernig's sign tests irritation of the meninges. When the patient lies flat, you flex the hip and knee to 90 degrees and then try to straighten the knee. If extending the knee provokes pain and resistance, that indicates meningeal irritation. This occurs because inflamed meninges, as seen in meningitis or subarachnoid hemorrhage, are stretched and irritate the nerve roots in the subarachnoid space during knee extension. By contrast, brain parenchyma problems usually present with changes in consciousness or focal deficits, peripheral nerve issues cause radicular pain along a nerve distribution, and cerebellar problems produce ataxia or coordination abnormalities rather than a positive Kernig sign.

Kernig's sign tests irritation of the meninges. When the patient lies flat, you flex the hip and knee to 90 degrees and then try to straighten the knee. If extending the knee provokes pain and resistance, that indicates meningeal irritation. This occurs because inflamed meninges, as seen in meningitis or subarachnoid hemorrhage, are stretched and irritate the nerve roots in the subarachnoid space during knee extension. By contrast, brain parenchyma problems usually present with changes in consciousness or focal deficits, peripheral nerve issues cause radicular pain along a nerve distribution, and cerebellar problems produce ataxia or coordination abnormalities rather than a positive Kernig sign.