A change in posture which takes place in some comatose patients, consisting of episodes of opisthotonos (a condition, caused by a tetanic spasm of the back muscles, in which the trunk is arched forward while the head and lower limbs are bent backward), rigid extension of the limbs, internal rotation of the upper extremities, and marked plantar flexion (turning the feet or toes toward the plantar surface or bottom) of the feet.

This can be produced by a variety of metabolic and structural brain disorders.