[Mesodiencephalic level of severe head injuries (author's transl)].

From the study of 65 severe traumatic comas, the authors describe the syndrome of mesodiencephalic dysfunction, because of its frequency and its particular clinical signs. This peculiar level of loss of consciousness is characterized by a coma without mimic and without awakening after painful stimulation, by a stereotyped motor pattern in extension, by a perseverance of the photomotor reflex, while fronto-orbicular and vertical oculo-vestibular reflexes are lacking. This level of deterioration appears to be a critical point in the natural history of comatose patients. If this level is not surpassed, the probability of early death due to evolutive neurological lesion is low (18%). One half of these patients have a good prognosis, more than 75% have an excellent recovery. This high probability of recovery is decreased by a half when the level of mesencephalic dysfunction is reached.