Retro-labyrinthine disorder in cases with peripheral facial palsy

In some previously reported cases, facial palsy, even in Bell's palsy, involved vestibular dysfunction. Vestibular dysfunction in facial palsy is considered to be due to a retro-labyrinthine disorder such as vestibular neuronitis or acoustic neuromas. For the past 9 years we have been using the galvanic body sway test (GBST) routinely for differential diagnosis of the vestibular system. This paper reports GBST detected, retro-labyrinthine disorders in facial palsy. From 1981 to 1989, equilibrium examinations were performed in 33 cases with Bell's palsy and in 12 cases with Hunt's syndrome within 2 weeks after the onset. GBST was tested in 10 out of the 17 cases showing canal paresis (CP) in the caloric test. Abnormal GBST responses were detected in 9 cases (90%), 4 (80%) with Bell's palsy and 5 (100%) with Hunt's syndrome. The incidence of abnormal GBST was very high not only in Hunt's syndrome but also in Bell's palsy. The results indicate that vestibular dysfunction combined with facial palsy is mainly due to a retro-labyrinthine disorder and suggest that what is called vestibular neuronitis might be caused by a pathogenesis similar to that of facial palsy.