[Electromyography and electroneurography in peripheral facial nerve paralysis (author's transl)]

The function of the facial nerve can be examined by 4 electrodiagnostic methods. In the nerve excitability test and electroneurography the facial nerve itself is stimulated over the stylomastoid foramen, whereas chronaximetry and electromyography are performed in the muscles. In the majority of patients with Bell's palsy it is possible to make a more or less favourable prognosis by clinical examination alone. As soon as the paralysis is evident only these diagnostic tests give an accurate prediciton. The early realisation of a poor prognosis is surgically important. Chronaximetry and electromyography do not facilitate early assessment of the prognosis. The nerve excitability test and electroneurography can assist in the prognosis within the first 6 days after the onset. This is especially so with electroneurography, in which the muscle action potentials are examined during facial stimulation. A continual decrease of amplitude of the action potential of 50% in 2 days and a complete loss of potential in 4 to 6 days indicate a total nerve degeneration with an unfavourable prognosis.