Chapter 38 - Bell's palsy and vestibular neuronitis

Abstract

Abstract Bell's palsy and vestibular neuritis are uncommon conditions but can be the cause of significant acute neurologic disability. Bell's palsy is the most common cause of facial weakness, whereas vestibular neuritis ranks second or third as the most frequent cause of sudden onset of dizziness and vertigo. The two conditions can occur either singly or in combination to cause facial weakness and debilitating dizziness. The disorders have been shown to be caused by a number of conditions, with the most frequent being idiopathic. The etiology of the disorders is also frequently presumed to be inflammatory and potentially related to reactivation of latent viral infection, most notably infection with herpes simplex virus type 1 (HSV-1). Bell's palsy has an incidence of 15–30 per 100 000, whereas the incidence of vestibular neuritis is less common, at 3.5 per 100 000. Men and women are equally affected, with a peak age of onset at 40 years of age. Individuals may spontaneously recover if left untreated; however, many do not fully recover from either disorder. Anatomically, connections between the facial and vestibular nerve bundles have been demonstrated, which may explain the occasional concurrent involvement of the nerves. Many histopathologic studies done for both conditions have identified the presence of latent HSV-1 infection in the geniculate ganglia as well as the vestibular ganglia, suggesting that the infection may contribute to causality of both entities, although evidence still remains circumstantial. The treatment is similar for the two conditions. Recent randomized double-blinded control studies done in both diseases using corticosteroids, antiviral agents, and the combination of both demonstrated that only the use of steroids as single therapy was effective in improving outcomes for both Bell's palsy and vestibular neuritis. The use of antiviral agents alone and in combination with steroids did not provide additional benefit.