Vestibular Function Test of Vestibular Neuritis in Acute and Compensated Stage

ABSTRACT

BACKGROUND: Vestibular neuritis (VN) is a common peripheral vestibulopathy. VN is most likely a partial rather than a complete vestibular paralysis, It has a natural history of gradual recovery within 1-6weeks. The investigation of vestibulo-ocular reflex (VOR) change in acute and compensated VN are relatively few in Korea. We performed the vestibular function test including electronystagmography (ENG) and rotary chair test (RCT) in the patients with acute and compensated VN, and evaluated the efficacy of ENG and RCT to know the degree of compensation. METHODS: Tweenty-four patients with acute VN, 14 patients who had cllinically compensated VN during follow-up period and 30 normal controls were studied. Mean intervals from symptom onset to test were 3.6 days (acute) and 102.5 days (com-pensated). RESULTS: Eight patients had asymmetrically impaired pursuit, and ten patients had asymmetrcally impaired OKN during acute stage. The degree of side differences in pursuit and OKN gain was correlated with intensity of spon-taneous nystagmus. In the acute stage, the gain of the VOR was reduced at low frequency (0.01-0.16Hz), but it was normal at high frequency (0.32Hz). Prolonged phase lead and gain asymmetries were present at all range of frequency. In the compensated stage, the gain, phase and symmetry of the VOR at all range of frequency were not different from those of controls, except for prolonged phase lead and asymmetry at 0.01 Hz. The rate of the patients with unilateral canal paresis was 100% at acute stage and 50% at compensated stage in mono-thermal cold caloric stimulation. CONCLUSIONS: These results suggested that pursuit and OKN abnormalities may be found in acute peripheral vestibu-lopathy, in which coarse spontaneous nystagmus may contribute to the development of these abnormality. Absence of caloric response does not indicate an complete absence of vestibular function and RCT is a useful method in evaluation of VOR status in patients with acute and compensated VN.