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Bilateral vestibulopathy can have various causes: ototoxicity (mainly caused by aminoglycosides), meningitis, bilateral tumours, neuropathies, bilateral sequential vestibular neuritis, or Meniére’s disease. Some types of bilateral vestibulopathy seem to arise from systemic autoimmune processes—for example, systemic lupus erythematosus, polychondritis, Cogan’s syndrome, or rheumatoid arthritis. About 20% of cases of bilateral vestibulopathy, however, remain “idiopathic” despite extensive diagnostic workup.1 Prompted by studies on immune mediated sensorineural hearing loss,2,3 we previously demonstrated IgG antibodies against the membranous labyrinth (ampulla, semicircular canal, saccule, and utricle) in sera from eight of 12 patients with “idiopathic” bilateral vestibulopathy, compared with one of 22 healthy controls and none of six patients with systemic autoimmune disease.4 Although the pathogenicity of these antibodies remains unclear, their appearance seems to indicate organ specific immune dysregulation.
Here we report a patient with a possible autoimmune bilateral vestibulopathy without hearing problems who recovered after steroid treatment. The recovery correlated with the disappearance of serum autoantibodies against inner ear structures.
Case report
A 55 year old man was admitted to the hospital with recurrent sudden monosymptomatic attacks of rotational vertigo lasting for 30 to 60 seconds over three years. For one year he had experienced unsteadiness of gait, particularly in the dark and on uneven ground, as well as blurred vision during head movement or when walking. He reported no disturbances of hearing. His medical history was otherwise normal; in particular there was no evidence of other neurological, otological, or rheumatological disorders, nor had there been any previous treatment with ototoxic drugs.
Clinical examination showed that the head impulse test (Halmagyi and Curthoys) was pathological on both sides. There was no evidence of oculomotor, central vestibular, or cerebellar disorders. Hearing function was also normal. Caloric irrigation (30°C and 44°C) showed a peak slow phase velocity of horizontal nystagmus of < 5°/s on both sides. The per- and postrotatory nystagmus lasted less than five seconds. An audiogram was normal. High resolution magnetic resonance imaging of the brain stem and computed tomography of the temporal bones were also normal. Testing for serum autoantibodies (determined as described previously4) against the inner ear structures, the semicircular canals, and otolith organs was positive (titre > 1:100). No antinuclear, anticytoplasmic, or antineural antibodies were detected.
On the assumption that an immune dysregulation caused the bilateral vestibular dysfunction, the patient was treated with steroids for six weeks, beginning with 100 mg/day methylprednisolone, and tapering the dose every third day by 20 mg/day until the patient was receiving only 20 mg/day for a duration of four weeks. Follow up examination at the end of this treatment showed that vestibular function had improved on both sides, with a peak slow phase velocity of 14°/s after caloric irrigation with warm water (44°C), and 12°/s on the right and 10°/s on the left with cold water (30°C). At that time serum autoantibodies remained positive.
Two years later the patient was seen again for follow up examination. The head impulse test was normal. Caloric vestibular testing showed a complete recovery of vestibular function with a peak slow phase velocity of > 25°/s (30°C/44°C) on both sides. Per- and postrotatory nystagmus were longer than 50 seconds on both sides. Serum autoantibodies against the vestibular organ had disappeared.
Comment
Immune mediated inner ear disease is characterised by sensorineural hearing loss that is most often rapidly progressive and bilateral, and may be accompanied by vestibular symptoms. Diagnosis of autoimmune inner ear disorders, however, is problematic as there is no universally accepted set of diagnostic criteria or diagnostic test.5 Our patient had only isolated vestibular signs and symptoms, typical of a bilateral vestibulopathy (the reported recurrent attacks of vertigo at the beginning of the disease are often found in this condition1). An autoimmunological aetiology was likely, as other causes had been excluded and raised titres of inner ear specific antibodies were detected. These decreased in parallel with clinical improvement after immunomodulatory treatment.
The treatment trials on autoimmune inner ear disorders that have so far been published have focused only on hearing loss.2 This single case shows that isolated vestibular dysfunction may also be improved by steroids.
We had hypothesised in our earlier study4 that some of the so called idiopathic vestibulopathies might be caused by autoimmune inner ear disorders. From the clinical course and response of this patient, we conclude that a short course of steroids may have an effect in patients with incomplete autoimmune induced bilateral vestibulopathy. We therefore recommend that inner ear autoantibodies be determined in bilateral vestibulopathy, and if there is evidence of an autoimmune disorder and vestibular failure is not complete, a short term treatment trial should be started to preserve or even improve vestibular function. This, however, needs to be further evaluated in a prospective study on a large group of patients.