Autoimmune Inner Ear Disease - Bilateral Progressive SNHL

A 42-year-old woman presents with rapidly progressive bilateral hearing loss over 6 weeks, fluctuating tinnitus, episodic vertigo, and aural fullness. She has a recent diagnosis of rheumatoid arthritis on methotrexate and new-onset scleritis. Audiometry shows the pattern marked **A** in the diagram: bilateral moderate-to-severe sensorineural hearing loss worse at low and mid frequencies (250–2000 Hz) with an upward-sloping contour, poor speech discrimination disproportionate to pure-tone thresholds, and reduced word-recognition scores. Tympanometry is Type A with variably absent acoustic reflexes. Which of the following is the most appropriate FIRST-LINE management for this audiometric pattern?