Background: Superior vermian subtype of arteriovenous malformation (AVM) coexisting with proximal feeder aneurysm on basilar-superior cerebellar artery (BA-SCA) junction is an extremely rare situation. We experienced a case of this rare entity presenting with subarachnoid hemorrhage (SAH), and herein, introduce the outline and clinical features of this experience together with the actual surgical video. Case Description: A 54-year-old man SAH patient with severe headache, disturbance of consciousness, and left oculomotor palsy was urgently admitted to our hospital. Imaging examination demonstrated superior vermian AVM with BA-SCA aneurysm, and both lesions were treated through two different approaches (left pterional craniotomy in conjunction with zygomectomy, and left posterior interhemispheric occipital transtentorial approach) in acute phase of SAH. Both lesions were completely disappeared postoperatively and the patient’s postoperative course was favorable, without symptomatic cerebral vasospasm. Although slight oculomotor palsy remained, the patient recovered well and was transferred to a rehabilitation hospital for further improvement. Conclusion: In the cases of AVM coexisting with proximal feeder aneurysm, presenting with SAH, disorders of intracranial venous return associated with an AVM can be a vital hindrance to managing cerebral vasospasm; therefore, treating both lesions in the acute phase may lead to good outcomes.

Recombinant tissue-type plasminogen activator with/without endovascular regimen is sometimes not effective for the treatment of acute hemodynamic stroke. Emergent superficial temporal artery-middle cerebral artery (STA–MCA) bypass has been reportedly effective in patients with progressive hemodynamic stroke; however, the effectiveness of urgent STA–MCA bypass for acute internal carotid artery (ICA) stenosis/occlusion with concomitant contralateral chronic ICA stenosis/occlusion, that is considered the worst hemodynamic situations, is unclear. Two cases of acute left ICA stenosis with concomitant right chronic ICA occlusion wherein both developed hemodynamic infarction and were initially treated by maximal medical treatment. Nevertheless, the patients' symptoms had gradually worsened, thus we performed emergency STA–MCA bypass for both cases. Postoperatively, deterioration of imaging and neurological findings was successfully stopped and the patients' condition gradually stabilized. An urgent STA–MCA bypass can be considered as a last resort to prevent progressive neurological deterioration for patients with progressive infarction due to ICA stenosis/occlusion concomitant with contralateral ICA stenosis/occlusion.