Which sign is positive when the neck is flexed causing hip and knee flexion?

Which sign is positive when the neck is flexed causing hip and knee flexion?

• A. Brudzinski's sign
• B. Babinski's sign
• C. Kernig's sign
• D. Nuchal rigidity sign

Answer: (A)

Brudzinski's sign is positive when passive neck flexion leads to involuntary flexion of the hips and knees. This reflexive movement happens because bending the neck stretches the meninges; in the setting of meningeal irritation from conditions like meningitis or subarachnoid hemorrhage, the stretch triggers a flexor response in the lower limbs. It directly ties neck movement to lower-limb reflexes, which is why this sign uniquely fits the description. Kernig's sign is the one where attempting to extend the knee with the hip flexed provokes pain or resistance, not the neck flexion–driven reflex described here. Babinski's sign is an abnormal plantar reflex indicating corticospinal tract involvement, not meningeal irritation. Nuchal rigidity describes stiffness of the neck itself, not a reflexive movement pattern when the neck is flexed.

Brudzinski's sign is positive when passive neck flexion leads to involuntary flexion of the hips and knees. This reflexive movement happens because bending the neck stretches the meninges; in the setting of meningeal irritation from conditions like meningitis or subarachnoid hemorrhage, the stretch triggers a flexor response in the lower limbs. It directly ties neck movement to lower-limb reflexes, which is why this sign uniquely fits the description.

Kernig's sign is the one where attempting to extend the knee with the hip flexed provokes pain or resistance, not the neck flexion–driven reflex described here. Babinski's sign is an abnormal plantar reflex indicating corticospinal tract involvement, not meningeal irritation. Nuchal rigidity describes stiffness of the neck itself, not a reflexive movement pattern when the neck is flexed.