A 48-year-old man from Mumbai presents with a 2-year history of recurrent episodes of severe spinning vertigo, each lasting 1–2 hours, occurring 2–3 times per month. He has progressive hearing loss in the right ear and constant right-sided tinnitus described as a 'roaring' sound. He also reports a sensation of fullness in the right ear before each vertigo attack. Audiometry shows low-frequency SNHL on the right (500–1000 Hz more affected than 4000 Hz). Electrocochleography (ECoG) shows elevated summating potential (SP) to action potential (AP) ratio on the right. What is the most appropriate next step in management?