A 63-year-old woman presents for workup to determine the reason for a gradual hearing loss over approximately 5 years and intermittent tinnitus over the last several months. Findings on physical and neurologic examination are entirely within normal limits, except for the presence of sensorineural hearing loss in the left ear. She has no cranial nerve deficits. An MRI of the brain with gadolinium reveals the presence of an extra-axial tumor in the region of the left cerebella-pontine angle. What is the most likely diagnosis?