Update on diagnostic procedures in third window syndromes

Background The diagnosis of third window syndromes often poses a challenge in clinical practice. Objective This paper provides an overview of diagnostic procedures in third window syndromes, with special emphasis on superior canal dehiscence syndrome (SCDS), large vestibular aqueduct syndrome (LVAS), and X-chromosomal malformation of the cochlea. Materials and methods A literature search was performed in PubMed up to December 2023. Furthermore, a selection of the authors’ own cases is presented. Results Audiovestibular tests for the diagnosis of third window syndromes are most often reported for patients with SCDS in the literature. In this context, cut-off values with different sensitivities and specificities have been defined for different outcome parameters of vestibular evoked myogenic potentials. Current developments include the application of electrocochleography, broadband tympanometry, video head impulse testing, and vibration-induced nystagmus. Genetic analyses are increasingly applied in LVAS. Conclusion The diagnosis of third window syndromes is always based on the synthesis of patients’ symptoms, clinical signs, audiovestibular test results, and imaging.