Electroneuronography (ENoG) is a test that measures and evaluates facial nerve function. The facial nerve is the 7th cranial nerve and is comprised of motor and sensory fibers. An ENoG is typically ordered by your physician when you are experiencing facial paralysis usually resulting from viral infections, trauma, neurological conditions or surgical intervention. Patients with facial paralysis can experience any of the following symptoms, which usually develop within the first 24 to 48 hours:
• Pain, numbness, or tenderness in the face/jaw/ear area
• Difficulty with eating, speaking or drinking (swallowing)
• Difficulty making facial expressions and smiling
• Difficulty closing the eye on the affected side
Typically, initial testing is performed at about 72 hours (or more) after the onset of symptoms.
The patient is seated in a comfortable recliner and electrodes are attached to the face and forehead. A mild electrical stimulation is briefly passed over the facial nerve. This electrical stimulation feels like a tapping on the face and sometimes causes the face to twitch. Although the test can be slightly uncomfortable for some patients, for others it is not bothersome at all. The entire test is very brief.
The purpose of the test is to compare the involved side (the side with paralysis) to the uninvolved side. Sometimes, the physician orders repeated ENoG testing over time to determine whether the problem is improving or worsening. ENoG testing enables the physician to make decisions regarding the need for surgical intervention and to determine prognosis. Repeat testing, if necessary, is usually performed at 3 to 5-day intervals until it is no longer required for diagnosis.
Bell’s Palsy is perhaps the most common cause of facial paralysis requiring an ENoG. The exact cause of Bell’s Palsy is unknown, but it is thought that it may be viral, bacterial, environmental or genetic in nature. Most patients experience spontaneous recovery within three to four weeks of developing Bell’s Palsy, but a small percentage of patients can experience a permanent weakness.
The prognosis of facial paralysis depends in part on its cause. The paralysis can sometimes resolve on its own, or it may require the help of medical or surgical intervention.