Acute peripheral unilateral vestibulopathy of the whole nerve causes increased impairment of spatial orientation and poorer long-term outcome.

Background: Acute peripheral unilateral vestibulopathy (UVP) is the third most common cause of peripheral vestibular vertigo. Etiologically, a viral inflammation is assumed. In most cases, an isolated dysfunction of the superior part of the vestibular nerve can be found (superior part UVP = sUVP), but an additional involvement of the inferior part has also been shown (whole nerve UVP = s+iUVP). The aim of the study was (a) to determine the prevalence of an additional inferior part involvement, (b) to quantify the extent of vestibular deficit comparing sUVP vs. s+iUVP and (c) to examine the long-term outcome focusing on psychological distress as well as long-lasting symptoms associated with dizziness.

Methods: 96 UVP patients were enrolled. They underwent a neuro-otological examination including measurements of cervical vestibular evoked myogenic potentials (cVEMP), subjective visual vertical (SVV), ocular torsion (OT), caloric testing and the clinical head impulse test (HIT) in the acute phase. The Symptom Checklist-90 R and the Vertigo Symptom Scale were examined at a mean follow-up interval of 4.0 years (± 0.4 years) after disease onset.

Results: Among the 96 patients (47 female; mean age 58 ± 14 years), additional involvement of the inferior nerve part was found in 35 cases (36%). These patients showed a significantly greater tilt of SVV (6.3° ± 4.4° vs. 4.2° ± 3.7°; F = 5.581, p = 0.020) and a more pronounced OT (15.1° ± 8.2° vs. 11.3° ± 7.4°; F = 4.770, p = 0.032) in the acute stage of the disease. The proportion of pathological HIT was significantly higher in the s+iUVP group (82.9% vs. 67.2%; Chi-Square = 20.167, p < 0.001). cVEMPs showed significantly decreased amplitude on the affected side (124.8 µV (± 10.3 µV) vs. 408.4 µV (± 26.6 µV); F = 61.911; p < 0.001). At long-term follow-up, the patients with s+iUVP had significantly increased anxiety scores as compared to patients with isolated sUVP (SCL-90 score for anxiety: 48.4 ± 3.8 vs. 41.6 ± 0.5; F = 4.231, p = 0.026).

Discussion: An additional lesion of the inferior part of the vestibular nerve led to increased vestibular dysfunction in acute UVP and might trigger long-lasting symptom persistence. Identifying these patients early might improve the clinical outcome, lead to a faster improvement and prevent secondary psychosomatic symptoms.