Drug-Induced Ophthalmoplegia

The evaluation of reflex activity has proved to be the most accurate way of clinically establishing the degree of unconsciousness in the comatose patient. Most clinicians examine the corneal reflexes, the pupillary reactions to light, and the deep tendon reflexes for this purpose. In some patients, however, these reflexes have not been an adequate indication of the true depth of coma; hence, in recent years, the ocular movements in response to head rotation or flexion (oculocephalic reflex, doll's head response) or to ice-water stimulation of the ears (oculovestibular response, caloric response) have been used as a more accurate indicator both of the depth of unconsciousness and of the absence or presence of structural brainstem disease. As an example of this, full conjugate excursion of the eyes elicited by either of these two stimuli in a comatose patient generally indicates an intact brainstem at or below the level of the third nerve nucleus. The converse is also generally believed; i.e., failure of eye movement is taken to mean that the substrate of unconsciousness is a primary of secondary parenchymal brainstem lesion.