Rich collaterals in clinically unsuspected basilar artery occlusion-as good as it gets.

Basilar artery occlusion (BAO) is generally considered an emergency and is associated with high mortality and poor functional outcome. Although cases with more benign course without thrombolysis treatment have occasionally been reported, to our knowledge there is only one previous report in which angiography, almost accidentally revealed a clinically unsuspected BAO. A 45-year-old man with treated hypertension and lipidemia had three distinct isolated episodes of dizziness, 2-3 months before he was referred by an internist for an ultrasound neurovascular evaluation. Neurological examination and extensive laboratory work-up was normal; however, transcranial Doppler (TCD) unexpectedly provided findings that first raised the suspicion of BAO, alerting for further work-up. Cerebral angiography demonstrated BAO, just beyond the anterior inferior cerebellar artery origin, as well as extensive intracerebellar collateral circulation. On 6-year follow-up, he remains normal with no further episodes, although serial TCD shows persistent BAO.