Histologic correlation of the degenerating facial nerve with electroneurography

The myogenic compound action potential (CAP) measured by electroneurography (EnoG) is hypothesized to correlate directly with the number of viable motoneurons in the facial nerve. In an animal model (cat), two independent ENoG techniques, standardized recording lead placement (SRLP) and optimized recording lead placement (ORLP), were used to record CAPs evoked from nerves undergoing degeneration. Normal test-retest variability simulated human studies. Peripheral counts of viable axons correlated with N1 amplitude (ORLP ENoG), peak-to-peak (absolute) amplitude (both ENoG techniques), and area under the negative phase of the diphasic CAP waveform (both ENoG techniques) recorded over the whisker pad. These results validate ENoG as a reliable indicator of neural integrity following traumatic lesions of the facial nerve.