MRI of the facial nerve during paralysis.

Gadolinium-enhanced MRI was used to evaluate 10 patients with Bell's palsy and one patient with facial paralysis secondary to Lyme disease. Nine of the eleven patients showed increased signal intensity of their facial nerve with gadolinium-enhanced MRI. In all nine patients, the facial nerve was involved at the labyrinthine, geniculate ganglion and proximal tympanic portions of the facial nerve, while two of the nine patients also had involvement of the mastoid segment of the facial nerve. Patients whose facial nerve enhancement was limited to the labyrinthine, geniculate ganglion and proximal tympanic facial nerve ultimately had complete return of facial function. Patients whose facial nerve enhanced in the mastoid segment experienced incomplete return of facial function. Gadolinium is effective in localizing the site of inflammation during facial paralysis. Those patients with enhancement localized to the labyrinthine, geniculate ganglion and proximal tympanic segments were more likely to regain complete facial function. In contrast, patients who had enhancement of the mastoid segment of the facial nerve had poorer prognoses for complete return of facial function.