Persistent vegetative state--clinical and electrophysiologic observations of 5 cases

Five patients who met the criteria of the persistent vegetative state (PVS), were studied for ten years. Among them, two had fallen into a deep coma after cardiopulmonary resuscitation, and the other three cases were due to cerebrovascular disorders. Four patients died within 10 years. Clinically, all five cases showed characteristic features of wakefulness without cognitive function and movement of the extremities. The brain stem reflexes, such as light reflexes of the pupils and corneal reflexes, were present. The electroencephalograms showed ample low amplitude and nonspecific slow waves. None revealed an isoelectric pattern. Brain stem auditory evoked potential (BAEP) studies were normal or slightly abnormal. Median nerve somatosensory evoked potential (SSEP) studies showed absence of a cortical response. These features suggest that the damage in PVS patients is mainly located in the cerebral cortex. Although electrophysiologic examinations are useful diagnostic procedures for PVS, clinical observation remains the basis of the diagnosis.