Vascular Etiology in Idiopathic Labyrinthitis: Implication of NLR and PLR and White Matter Changes.

Abstract

Objective.: Vascular mechanisms have been implicated in idiopathic acute unilateral audiovestibulopathy (iAUAV, also known as labyrinthitis), especially in older patients. We investigated the platelet-to-lymphocyte ratio (PLR), neutrophil-to-lymphocyte ratio (NLR), and white matter changes in patients with iAUAV/labyrinthitis to determine the potential vascular etiology in this disorder.

Methods.: We retrospectively analyzed complete blood count (CBC) data from patients aged over 50 years and diagnosed with iAUAV/labyrinthitis at a tertiary hospital in South Korea between March 2018 and June 2025. CBC data, Fazekas scores for white matter changes, video head-impulse tests (vHIT), and bithermal caloric test results were compared with those of patients with acute unilateral peripheral vestibulopathy (AUVP, i.e., vestibular neuritis [AUVP/VN]) and age- and sex-matched healthy controls.

Results.: A total of 74 patients with iAUAV/labyrinthitis (mean age± standard deviation [SD] = 68± 9 years; 34 male), 84 with AUVP/VN (65± 9 years; 46 male), and 58 healthy controls (68± 10 years; 26 male) were included. Both NLR (p<0.001) and PLR (p=0.003) were higher in the iAUAV/labyrinthitis group than in the AUVP/VN or control groups. Patients with iAUAV/labyrinthitis had higher Fazekas scores than those with AUAV/VN (p=0.002). Compared to AUVP/VN, iAUAV/labyrinthitis was associated with a higher PLR (p=0.038), higher Fazekas score (p=0.011), increased VOR gain for the horizontal canal (p<0.001), and decreased VOR gain for the posterior canal (p=0.005).

Conclusion.: Elevated PLR and prominent white matter changes suggest a microvascular etiology of iAUAV/labyrinthitis in older adults. These serologic and imaging markers may complement standard neurotologic assessments in diagnosing iAUAV/labyrinthitis.