[The determination of the sum potential amplitude for the prognostication of facial paresis of viral etiology].

In 29 patients with facial pareses of viral etiology the sum potential amplitude of the M. orbicularis oris was determined in a comparison of the two sides for prognostication purposes. If the sum potential amplitude is reduced by less than 70 per cent a return of good functions can be expected within 6-8 weeks. If the reduction of the sum potential amplitude lies between 70 and 95 per cent, a reliable prognosis is not possible, whereas with values below 95 per cent the paresis does not improve at all or hardly improves within 6-8 weeks. An evaluation of the returned function, about 1 year after the beginning of the paresis, i.e. at a time when the regeneration is basically completed, shows that all cases with an originally poor function (judged 6-8 weeks after onset of paresis) had changed into cases with a moderate function, and all cases with an originally moderate function had turned into cases with a good function. In another study concerning patients with idiopathic facial paresis the same method yielded results comparable to those of the above-mentioned study, so that the conclusion can be drawn that in the prognostication of the peripheral facial paresis by means of determining the sum potential amplitude-regardless of whether the facial paresis is of viral or idiopathic etiology-the same yardsticks have to be applied.