Lermoyez Syndrome: A Systematic Review and Narrative Synthesis of Reported Cases.

Objectives: Lermoyez syndrome (LS) is a rare variant of endolymphatic hydrops with a unique clinical presentation characterized by reversible sensorineural hearing loss preceding vertigo. This review aims to synthesize available literature on LS to clarify its clinical characteristics, diagnostic approach, management strategies, and outcomes, and to highlight the distinguishing features from Menière's disease (MD). Methods: A systematic literature review according to PRISMA guidelines was conducted from 1919 to 2025. The extracted data included demographics, symptom profiles, audiovestibular testing, imaging findings, treatment approaches, and patient outcomes. Results: A total of 23 studies were identified, reporting 53 individual cases of LS. Patients ranged from 27 to 85 years of age, with a mean age of 50.34 years and a male predominance (64.1%). The hallmark of LS across cases was a reproducible clinical pattern of unilateral low-frequency hearing loss followed by vertigo and subsequent auditory recovery. Audiometry typically confirmed reversible sensorineural hearing loss, while vestibular tests and imaging were often unremarkable, primarily used to exclude alternative diagnoses. Treatment approaches varied and were often based on MD protocols, including dietary modifications, vasodilators, diuretics, and vestibular suppressants. Prognosis was generally favorable, with most patients experiencing both hearing recovery and symptom resolution. Conclusions: LS remains a clinically distinct but underrecognized inner ear disorder. Its defining feature-the paradoxical improvement in hearing after vertigo-distinguishes it from Menière's disease and should prompt clinicians to consider LS in differential diagnosis. Due to the rarity of LS and the lack of standardized guidelines, diagnosis and treatment rely on careful clinical assessment and individualized management strategies.