Which finding supports a diagnosis of benign paroxysmal positional vertigo?

The finding of horizontal nystagmus with rapid head movement is characteristic of benign paroxysmal positional vertigo (BPPV). In cases of BPPV, specific movements of the head trigger episodes of vertigo, during which a patient may exhibit nystagmus—a rapid, uncontrolled eye movement. This nystagmus is typically transient and can be observed when the patient is subjected to certain positional changes that provoke their symptoms. The horizontal component of the nystagmus is particularly associated with BPPV due to the involvement of the horizontal semicircular canal.

Other findings, such as tinnitus, new onset of hearing loss, or a duration of symptoms greater than 2 years, are not consistent with a diagnosis of BPPV. Tinnitus and hearing loss suggest a more complex inner ear pathology, possibly related to conditions like Meniere's disease or vestibular neuritis. Similarly, if symptoms persist beyond 2 years, this indicates a chronic issue that is not typical for BPPV, which is characterized by brief episodes related to head position changes. Therefore, horizontal nystagmus in response to rapid head movements serves as a clear indicator of BPPV.