[Experience with flash-evoked visual potentials in unconscious patients in the neurologic intensive care station]

Evoked potential monitoring has become a widely used procedure in the evaluation of stuporous patients on neurological intensive care units. Currently BAEP and SEP are preferentially employed. VEP monitoring is a relatively uncommon procedure, because late evoked potentials tend to be relatively unstable, varying in amplitude to a moderate extend from changes of temperature, drugs, attention and the level of consciousness. A valuable approach of VEP monitoring on intensive care units are structures of the visual system at risk in vascular disease of the vertebrobasilar system or during evaluated intracranial pressure (EIP). This study uses the data of 20 stuporous patients presenting with either intracranial mass lesions or vascular diseases of the vertebrobasilar system and 20 control persons. Light emitting diode (LED)-VEP are compared with checkerboard stimulation in control persons using the technique of cross-correlation. The comparison of the control group with patients using LED-VEP allows definition of limits for normal variation as a base for identification of significant changes. Despite methodical restrictions of LED-VEP, our results are in favour of serial studies in patients with EIP. There are no corresponding findings in LED-VEP and vascular lesions of the retrochiasmatic visual system.