[Value of evoked somatosensory potentials of the facial nerve]

Abstract

We assessed the somatosensory evoked potentials (SEP) contribution to the evaluation of peripheral pathologies of the facial nerve. SEPs to electrical stimulation of the internal face of the auricle (Ramsay-Hunt zone) were recorded in 8 normal subjects and in 6 patients with unilateral peripheral facial palsy. Significant and reproducible cortical responses were obtained in all normal subjects and to stimulation of the healthy facial nerve in all patients. Brain mapping performed in one normal subject allowed us to locate the different activities on the cortex and to differentiate those from a possible auditory nerve response to electrical stimulation. When stimulating the pathological side, the cortical activities were altered when compared with those obtained by stimulation of the healthy side. In conclusion, the stimulation of the Ramsay-Hunt zone evokes a cortical response like those obtained by somatosensory stimulation of other cutaneous territories. These responses are significantly altered in peripheral facial palsy. Additional studies are needed to establish the prognostic value of these abnormalities.