[Usefulness of multimodal evoked potentials and the electroretinogram in the early diagnosis of brain death].

INTRODUCTION AND METHODS

We studied 72 patients fulfilling all the criteria for brain death (BD) by means of a series of tests: brain stem auditory visual evoked potentials (VEP), short latent period somatosensory evoked potentials (SEV) and electroretinogram (ERG).

RESULTS

Three characteristic PEATC patterns were identified: bilaterally flat (73.34%), bilateral I wave (16.66%) and unilateral I wave (10%). The N20 wave of the SEV and other later cortical components were not seen in any patients, whilst the so-called subcortical components were partially or totally maintained. The use of non-cephalic data permitted discussion as to the origin of the subcortical components. When cephalic data was used to obtain the ERG and the VEP, the a and b waves of the ERG were recorded in all cases, whilst in the VEP channel waves of inverse polarity appeared of similar morphology and the same latency, but of lower amplitude than those of ERG. When a non-cephalic reference was used, the morphology and latency of the ERG components were unchanged, whilst no response was obtained from the VEP channel. This electrophysiological pattern indicates that the only part of the visual pathway of patients with BD to maintain electrical activity is the retina.

CONCLUSION

The application of this set of tests permits early diagnosis of BD, which is basic for transplantation.