Utility of EMLA in the relief of pain associated with electroneurography

Electroneurography (ENoG) is an electrodiagnostic procedure used to evaluate facial nerve deficit. A problem with application, however, is pain. Several studies have demonstrated that topical application of the eutectic mixture of lidocaine and prilocaine has an anesthetic effect on superficial and deep tissues. The present study was intended to determine if successful anesthesia of the trigeminal nerve could be achieved without altering the impulse transmission on the facial nerve. ENoG responses were measured at stimulation levels of 8, 16, 24, and 30 to 40 ma before and after Eutectic Mixture of Local Anesthetic (EMLA) application. A significant reduction in pain sensation was observed at stimulation levels of 8 and 16 ma while the amplitude of the response was not significantly changed. At the higher stimulation levels, namely, 24 and 30 to 40 ma, no significant reduction in pain or amplitude was observed. We concluded that, at moderate stimulation levels (> or =16 ma), EMLA reduces the pain associated with ENoG testing without affecting the amplitude of the muscular response.