Answer 3

Decerebellate posture characterised by opisthotonus with the thoracic limbs extended, flexion of the hips and normal mentation. Such abnormal posture indicate a lesion affecting the rostral part of the cerebellum which inhibits the stretch reflex mechanism of antigravity muscles (extensor muscle tone). The flexion of the hips is caused by increased tone in the iliopsoas muscles. In the absence of history of head trauma and taking into account the acute onset, differentials include mainly cerebro-vascular accident (particularly cerebellar infarct) and less likely decompensation from progressive intra-cranial diseases such as brain neoplasm or malformation.

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