Introduction: Aneurysms of the vertebrobasilar junction are rare, but when present, they are often associated with fenestration of the basilar artery. Frequently, the endovascular treatment is the first choice due to the complex anatomy of the posterior fossa.

Clinical case: A 68-year-old man from Lima, who denies important antecedents, was admitted to the emergency unit with intense holocranial headache, diplopia, posterior cervical pain and vomiting, without loss of consciousness. The neurological exam showed: score of 15 in the Glasgow coma scale (GCS), no pupillary alteration, no motor or sensitivity deficit, palsy of the left sixth cranial nerve and Hunt-Hess grade II. For decision making, the patient underwent digital subtraction angiography (DSA) through the right femoral artery with 3D reconstruction (03-08-2018) which showed evidence of fenestration of the basilar artery associated with saccular aneurysm. An aneurysm coil embolization was performed without complications. The patient was discharged maintaining diplopia, with paralysis of the left sixth cranial nerve, but without any other complaints or neurological symptoms.

Conclusion: Fenestrated basilar artery aneurysms are rare and complex vascular diseases and their treatment improved with the advent of the 3D angiography and the development of the endovascular techniques. The endovascular treatment by coil embolization is the first option although other endovascular techniques have also been described.