Decerebrate posturing indicates which of the following?

• A. Mild concussion
• B. Severe brain stem injury
• C. Cerebellar damage
• D. Spinal cord injury

Answer: (B)

Decerebrate posturing is a sign of brainstem involvement. When the brainstem is severely damaged, the balance of signals that normally regulate muscle tone is lost, leading to an almost rigid, extensor posture of the arms and legs with the wrists pronated and the head arched. This pattern reflects disruption of pathways in the brainstem that control extensor tone and reflexes, and it is considered a poor prognostic indicator in a patient with altered consciousness.

Mild concussion would not produce this abnormal posturing; symptoms are typically transient and include headache, dizziness, and confusion without fixed motor postures. Cerebellar damage mainly causes coordination problems, ataxia, and intention tremor rather than a fixed extensor posture. Spinal cord injury can cause weakness or spasticity below the level of injury, but decerebrate posturing specifically points to dysfunction within the brainstem rather than the spinal cord.