A 42-year-old woman from Delhi presents with a 6-month history of episodic vertigo lasting 4–6 hours, accompanied by tinnitus, aural fullness, and low-frequency sensorineural hearing loss. Audiometry confirms unilateral low-frequency SNHL. She denies recent head trauma or ototoxic drug exposure. Caloric testing shows reduced caloric response on the affected side. She is currently on no medications. What is the most appropriate next step in management?