Ocular motor dysfunction in stupor and coma.

Ocular motor disorders in stupor and coma are important clinical signs which are easily accessible with observation and a few bedside manoeuvres. Although the manifold signs of ocular motor dysfunction may be confusing to most clinicians, many of the signs can be attributed to clear pathophysiological mechanisms. This holds for conjugate eye deviations as well as for most spontaneous eye movements in coma. Using simple methods to elicit reflex eye movements, in most cases a lesion site within or outside the brain stem can be determined. It is stressed that an exact description and documentation of the ocular motor deficit is necessary. The following key aspects should be included in such a documentation: pupil size and reaction, conjugate or disconjugate eye position, spontaneous eye movements and VOR elicited either by head rotation or caloric irrigation. The latter allows assessment of the ocular motor integrator. The VOR may be intact, indicated by full compensatory eye movements, but the gaze-holding mechanism (integrator) can be defective, thus permitting the eyes to drift back to the primary position.