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Decerebrate rigidity

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Definition

noun

An involuntary posturing whereby the arms are extended on the sides while the head is arched back, as exhibited by an individual with lesions or compression in the midbrain


Supplement

Abnormal posturing associated with severe brain injury are of three types: (1) decorticate posturing, (2) decerabrate posturing, and (3) opisthotonus (where the head and the back are arched backward).

In decerebrate posturing (also called decerebrate response or rigidity), the abnormal posturing is characterized by the arms extending at the sides. It differs from the decorticate posturing wherein the arms are flexed over the chest. The decorticate posturing is an indication of a lesion or injury in the cortex. However, it can progress to decerebrate posturing, which means that the lesion progresses from the cortex to the brainstem. Further progression could lead to the final phase where the muscles lose rigidity and become flaccid, in which in this case the condition becomes an indication of fatality or death.

Decerebrate posturing is characterized by an involuntary extension of the upper extremities (arms) while the head is arched back. The legs are also extended. The arms may rotate internally. The body of the patient appears rigid and the teeth are clenched.

Decerebrate posturing indicates brain stem damage, particularly below the level of the red nucleus. It is manifested by people with midbrain lesions or compression.



Synonym(s):

  • decerebrate response
  • extensor posturing
  • decerebrate posturing