Option B is correct because these findings (unidirectional nystagmus, abnormal Head Impulse Test, and absence of skew deviation) strongly indicate a peripheral vestibular lesion, such as vestibular neuritis, and make the diagnosis of stroke unlikely | Option A is incorrect because reassuring HINTS findings (abnormal Head Impulse Test) effectively rule out stroke in the posterior circulation | Option C is incorrect because CT is not sensitive for acute brainstem and cerebellar strokes, and in any case, HINTS findings are reassuring and do not warrant urgent imaging | Option D is incorrect because vestibular migraine rarely causes persistent vertigo for days with spontaneous nystagmus and abnormal Head Impulse Test | Consult a vestibular specialist if symptoms do not improve within 72 hours or if new central neurological symptoms appear, as this may indicate an alternative diagnosis or complications | The single variable that changes the answer: presence of a normal Head Impulse Test (instead of abnormal) in the context of acute vertigo converts the findings to "concerning" and warrants immediate MRI | Consultant Pearl: HINTS examination (Head Impulse Test, Nystagmus, Test of Skew) is more sensitive than early MRI for diagnosing posterior circulation stroke in the first hours | Sources: vertigo.pdf — p. 4; CUMMINGS OTOLARYNGOLOGY–HEAD AND NECK 7th Ed p1.pdf — p. 1075; Scott Browns Otorhinolaryngology 8th edition volume 2 .pdf — p. 824