Reliability of diagnostic procedures in facial paralysis with special reference to magnetic resonance tomography

Facial nerve palsy is commonly examined using a variety of topodiagnostic and electrophysiological tests. More recently, MRI has also been used to study lesions of the facial nerve. Due to varying time intervals between the onset of symptoms and clinical examination, however, the diagnostic value of these procedures remains limited. In the present study, 30 patients with facial nerve palsy of diverse origin were examined with MRI (1.5 Tesla magnetom) using a special surface coil and 30 degrees parasagittal slices of 3 mm thickness. These special modifications enabled us to visualize the nerve in its entire course through the temporal bone. After the application of Gd-DTPA the enhancement of the contrast medium could be verified in all cases. A moderate enhancement in the geniculate ganglion as well as in the labyrinthine segment correlated with a good prognosis in terms of complete restoration of facial nerve activity, while an increased enhancement correlated with a poor prognosis. Our results indicate that MRI is of superior diagnostic value as compared to clinical and electrodiagnostic tests, at least in the patients we examined in this study. Still, further evaluations are necessary to justify a possible routine clinical use of this procedure.