Determining the Pathway of the Blink Reflex through Transcutaneous Electrical Stimulation of the Facial Nerve over the Stylomastoid Foramen

Abstract

The afferent pathway of the late response (R2 component) of the blink reflex in response to transcutaneous electrical stimulation of the facial nerve over the stylomastoid foramen remains uncertain. The two major hypotheses regarding the afferent pathway of R2 are that it may consist of either the trigemino-facial or the facio-facial reflex. This study was performed to determine the afferent pathway of R2. Ninety-one patients with acute unilateral peripheral facial palsy and 21 controls were studied. The degree of facial nerve damage was classified into three groups: mild, moderate, and severe according to their electroneurographic value. In each group, the appearance rate, latency, and area under the curve of contralateral R2 elicited by electrical stimulation of the injured facial nerve over the stylomastoid foramen were measured and compared with those of controls. The contralateral R2 parameters did not differ between the patient groups and the controls. The results indicate that the afferent pathway of R2 is mediated not only through the facial nerve. We conclude that the auriculotemporal nerve (V3) and the great auricular nerve (C2, C3) may also contribute to the afferent pathway of R2.