Which sign is elicited by passively flexing the neck to cause hip and knee flexion?

Which sign is elicited by passively flexing the neck to cause hip and knee flexion?

• A. Kernig sign
• B. Oppenheim sign
• C. Babinski sign
• D. Brudzinski sign

Answer: (D)

When the neck is passively flexed, this sign appears as an involuntary flexion of the hips and knees. That response is characteristic of Brudzinski sign, a manifestation of meningeal irritation such as in meningitis or subarachnoid hemorrhage. The neck flexion stretches the meninges, and the protective stretch reflex brings the hips and knees into flexion to relieve tension. Other signs test different mechanisms: Kernig sign involves resistance or pain when trying to straighten the leg with the hip flexed and knee extended, not simply neck movement; Babinski sign is an upward response of the great toe with fanning of the other toes upon plantar stimulation, indicating corticospinal tract involvement; Oppenheim sign is a similar upper motor neuron sign elicited by firm palmar or anterior tibial stimulation along the shin. These are not produced by passively flexing the neck.

When the neck is passively flexed, this sign appears as an involuntary flexion of the hips and knees. That response is characteristic of Brudzinski sign, a manifestation of meningeal irritation such as in meningitis or subarachnoid hemorrhage. The neck flexion stretches the meninges, and the protective stretch reflex brings the hips and knees into flexion to relieve tension.

Other signs test different mechanisms: Kernig sign involves resistance or pain when trying to straighten the leg with the hip flexed and knee extended, not simply neck movement; Babinski sign is an upward response of the great toe with fanning of the other toes upon plantar stimulation, indicating corticospinal tract involvement; Oppenheim sign is a similar upper motor neuron sign elicited by firm palmar or anterior tibial stimulation along the shin. These are not produced by passively flexing the neck.