Among patients with positive nystagmus during positional testing, definite BPPV accounts for only 65.4%. The main finding in this clinical study comparing patients with definite BPPV and patients with non-definite BPPV is that positional vertigo attacks in patients with non-definite BPPV can be distinguished from those in patients with definite BPPV on the basis of spontaneous nystagmus, posthead-shaking nystagmus, nystagmus intensity and patterns, duration, and associated headache. Over one-third of non-definite BPPV patients showed intricate multiple positional nystagmus, in which only a portion of the positional nystagmuses were consistent with BPPV. None of these patients experienced complete resolution either in terms of symptoms or nystagmus, while half of these patients had partial symptom resolution in which positional nystagmus of the suspected affected canal disappeared and nystagmus in the other positions remained unchanged. There is a possibility that vestibular migraine might present nystagmus that exhibits characteristics in accordance with otoconia in certain positions, or these patients may concurrently experience both vestibular migraine and BPPV.