strictly speaking based on my own opinion, i would expect a blind pt with BPPV to have a positive hallpike... while nystagmus may or may not be present, you should at least have some vertigo... though i've never had the experience of dealing with that...
i'd be curious to see theMRI... does the patient complain about general dizziness or actual vertigo? and were they blind from birth? i wonder if that would make a difference too... would a blind-since-birth person experience vertigo?
good questions.......
patrick