Which motor postures are classic abnormal responses to stimuli in brain stem abnormalities?

Which motor postures are classic abnormal responses to stimuli in brain stem abnormalities?

• A. Decorticate posturing
• B. Spastic hemiparesis
• C. Flaccid paralysis
• D. Decorticate and decerebrate posturing

Answer: (D)

Abnormal motor posturing in response to stimulation reflects disruption of brainstem control of posture and tonu. Decorticate posturing shows arms flexed and adducted with legs extended, arising from damage above the red nucleus (cerebral hemispheres or diencephalon). Decerebrate posturing is an extension pattern of all limbs, indicating brainstem involvement at or below the red nucleus. When brainstem abnormalities are present, these two postures are classic reflexive responses to stimuli, signaling severe injury and a poor prognosis. Spastic hemiparesis is a unilateral UMN deficit rather than a stereotyped postural response. Flaccid paralysis describes loss of muscle tone, not a characteristic posturing to stimuli. Decorticate posturing alone covers one pattern, but the combination of decorticate and decerebrate posturing best reflects brainstem involvement across the spectrum.

Abnormal motor posturing in response to stimulation reflects disruption of brainstem control of posture and tonu. Decorticate posturing shows arms flexed and adducted with legs extended, arising from damage above the red nucleus (cerebral hemispheres or diencephalon). Decerebrate posturing is an extension pattern of all limbs, indicating brainstem involvement at or below the red nucleus. When brainstem abnormalities are present, these two postures are classic reflexive responses to stimuli, signaling severe injury and a poor prognosis. Spastic hemiparesis is a unilateral UMN deficit rather than a stereotyped postural response. Flaccid paralysis describes loss of muscle tone, not a characteristic posturing to stimuli. Decorticate posturing alone covers one pattern, but the combination of decorticate and decerebrate posturing best reflects brainstem involvement across the spectrum.