Electroneuronography

Electroneuronography or electroneurography (ENoG) is a neurological non-invasive test used to study the facial nerve in cases of muscle weakness in one side of the face (Bell's palsy). The technique of electroneuronography was first used by Esslen and Fisch in 1979 to describe a technique that examines the integrity and conductivity of peripheral nerves. In modern use, ENoG is used to describe study of the facial nerve, while the term nerve conduction study is employed for other nerves. Electroneuronography or electroneurography (ENoG) is a neurological non-invasive test used to study the facial nerve in cases of muscle weakness in one side of the face (Bell's palsy). The technique of electroneuronography was first used by Esslen and Fisch in 1979 to describe a technique that examines the integrity and conductivity of peripheral nerves. In modern use, ENoG is used to describe study of the facial nerve, while the term nerve conduction study is employed for other nerves. It consists of a brief electrical stimulation of the nerve in one point underneath the skin, and at the same time recording the electrical activity (compound action potentials) at another point of the nerve's trajectory in the body. The response is displayed in a cathode ray tube (CRT) or through the video monitor of a computer. The stimulation as well as the recording are carried out by disc electrodes taped to the skin, and the technician may use electrically conducting gel or paste to bolster the signals being input and output. Alternatively, the recording electrodes may also be used to pick up the electrical activity of a muscle innervated by that nerve. In such instances electroneuronography is closely related to electromyography. It is performed by an audiologist, who carries out tests to compare the two sides of the face. The stimulation electrode is located at the stylomastoid foramen and the recording electrode is located near the nasolabial fold. The ENoG test is the only objective measure of facial nerve integrity.