Transient Ischemic Attack Due to Unruptured Basilar Artery Aneurysm.

Intracranial aneurysms are typically asymptomatic. They are usually incidentally detected or detected only after rupture. Ischemic stroke or transient ischemic attack (TIA) due to unruptured intracranial aneurysms (UIAs) is rare. A 79-year-old male with well-controlled hypertension and hypothyroidism, presented with complaints of sudden-onset weakness of the right upper limb and lower limb, followed by altered sensorium and a fall. Two hours later, he had fully recovered. Neurologic examination was unremarkable. Computed tomography of the brain revealed a dilated and tortuous basilar artery, suggestive of an aneurysm compressing the left midbrain and pons, with no evidence of intracranial bleed. Further, magnetic resonance imaging with an angiogram revealed multiple lacunar infarcts in the posterior circulation, distal to the aneurysm. Finally, a cerebral angiogram confirmed a partially thrombosed, fusosaccular aneurysm, arising from the left vertebral and basilar arteries. In view of frailty and long vessel segment involvement, surgery was not advised. He was treated medically, with appropriate antiplatelets and prophylactic antiepileptics. On follow-up, he had no neurologic deficit and had suffered no later ischemic or hemorrhagic events. UIAs may cause brainstem strokes via thrombosis of the parent vessel, emboli from the thrombus, or compression of the parent artery. In our case, compression, the least common mechanism, appears to have caused the TIA, with emboli potentially responsible for the silent lacunar infarcts. Fusiform aneurysms of the vertebrobasilar system have a poor natural history. In elderly patients presenting with ischemic events due to UIAs of the vertebrobasilar system, surgical intervention can be risky. So, medical treatment with antiplatelets is recommended. UIAs should be considered in the differential diagnosis of patients with TIAs, and such patients should have a visualization of intracranial arteries.