[Selection of electrophysiological investigations for diagnosis in idiopathic facial palsy. Twenty years experience in an ENT department]

Abstract

Electrophysiological exploration of the facial nerve requires different tests to differetciate the importance of the block, denervation and canal conduction. We must answer five questions: 1) Assessing the degree and the phase of the nerve lesion, 2) Deciding on the advisability of a facial decompression in the early stage of the palsy, 3) Evaluating the prognosis, 4) Choosing the best therapeutic approach, 5) Detecting facial hyperkinesis in an infraclinic period. In order to answer these questions, we select the following methods: 1) Quantified Electroneuronography should be applied as early as the 2nd day after onset, repeated on the 7th and 10th days. Unfortunately this is not always possible for practical reasons. In any case a minimum of two investigations should be performed during the 12 first days. 2) We add Computer EMG in order to control the evolution of the blocked fibers with regard to denervated fibers. 3) Blink reflex and Stapedius reflex are investigated from the 3rd day. After the acute phase of the palsy, recovery is detected by the reappearance of the blink and stapedius reflexes and the evolution of the computed EMG. These tests are sufficient for answering the five questions mentioned above without discomfort for the patient.