A nurse is reviewing the record of a child with increased ICP and notes that the child has exhibited signs of decerebrate posturing. On assessment of the child, the nurse would expect to note which of the following if this type of posturing was present?
A. Abnormal flexion of the upper extremities and extension of the lower extremities.
B. Rigid extension and pronation of the arms and legs.
C. Rigid pronation of all extremities.
D. Flaccid paralysis of all extremities.
Correct Answer: B. Rigid extension and pronation of the arms and legs.
Decerebrate posturing is characterized by the rigid extension and pronation of the arms and legs. Synonymous terms for decerebrate posturing include abnormal extension, decerebrate rigidity, extensor posturing, or decerebrate response. Decerebrate posturing can be seen in patients with large bilateral forebrain lesions with progression caudally into the diencephalon and midbrain. It can also be caused by a posterior fossa lesion compressing the midbrain or rostral pons.
Option A: Synonymous terms for decorticate posturing include abnormal flexion, decorticate rigidity, flexor posturing, or decorticate response. The mechanism for decorticate posturing is not as well studied as that of decerebrate. Phylogenetically, the region of the red nucleus within the midbrain plays a significant part in locomotion. In primates, the rubrospinal tract influences primitive grasp reflexes, particularly in infants, and is, incidentally, responsible for crawling.
Option C: Pronation is a natural movement of the foot that occurs during foot landing while running or walking. Composed of three cardinal plane components: subtalar eversion, ankle dorsiflexion, and forefoot abduction. These three distinct motions of the foot occur simultaneously during the pronation phase.
Option D: Flaccid paralysis is a neurological condition characterized by weakness or paralysis and reduced muscle tone without other obvious cause (e.g., trauma). This abnormal condition may be caused by disease or by trauma affecting the nerves associated with the involved muscles.
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