[Accuracy of the prognostic diagnosis in acute peripheral facial palsy]

The important factors in the prognostic diagnosis of acute peripheral facial palsy are (1) the causal disease, (2) the site of injury and (3) the degree of injury, although the age of the patient, complication, treatment method and initial day of treatment are also important. Among these 3 factors, the degree of injury is most strongly related to the prognosis. However, the diagnosis of etiology is the most important for the selection of the treatment method. Above all, the differential diagnosis between Bell's palsy and zoster sine herpete (Ramsay Hunt syndrome), is the most significant. However, it is impossible to diagnose all patients with complete accuracy within 3 days after the onset of palsy, even using molecular biological examination including polymerase chain reaction analysis. The diagnosis of the site of injury does not contribute to the prediction of prognosis or the selection of treatment method, except for the determination of the approaching route of the facial nerve decompression for traumatic facial palsy. The scoring system of facial movement (40-point method), nerve excitability test (NET), electroneurography (ENoG), transcranial magnetic stimulation (TMS) and stapedial reflex (SR) are commonly used to estimate the degree of injury. To estimate the accuracy of these examinations, sensitivity and specificity of the tests were calculated according to the findings within 3 days after the onset of palsy and the outcome of 116 patients with Bell's palsy and 31 with Ramsay Hunt syndrome. According to the results, none of these tests seem to be a perfect diagnostic examination for the completely precise prediction of prognosis. However, a patient is predicted to have a good prognosis, if the following 3 findings are observed: (1) more than 10 points in the 40-point scoring system of facial movement, (2) a positive response to TMS and (3) a positive response to SR. An antidromic facial nerve response probably contributes to a precise prediction of prognosis within 3 days after the onset of facial palsy.