Alternative middle-flow extracranial-intracranial cerebral bypass using distal branches of the external carotid artery in patients with complex cerebral aneurysms (clinical cases and literature review)

Background. The treatment of complex cerebral aneurysms is still remained the great challenge for neurosurgeons. There is a large choice of intravascular techniques for excluding the complex cerebral aneurysms from the blood flow: endovascular embolization with microcoils, usage of flow-diverting stents, balloon angioplasty and stenting of extra- and intracranial segments of the main cerebral arteries. At the same time, the microsurgical treatment of cerebral aneurysms has not lost its relevance and remains the most radical method of treatment. However, simple clipping or reconstruction of complex aneurysm wall is not always possible. In such cases, trapping of parent artery and revascularization of the required blood supply territory are used. Aim. To present the two clinical cases of patients with complex intracranial aneurysms without the possibility of endovascular treatment, who underwent parent artery trapping and alternative middle flow extracranial-intracranial (EC–IC) bypass as well as to conduct the literature review concerning the key aspects of this topic. Clinical cases. This article presents two patients operated on for complex intracranial aneurysms. The first patient had a complex fusiformsaccular aneurysm of the left middle cerebral artery (MCA) with a frontal M2 segment of the left MCA extending from the fusiform dome; the second patient had a giant saccular aneurysm of the supraclinoid segment of the left internal carotid artery (ICA) and a complete posterior trifurcation on the left. Endovascular treatment was considered as impossible. The trapping of the parent artery and performing of middle-flow EC–IC bypass using the distal branches of the external carotid artery (ECA) were conducted. Intraoperative frameless neuronavigation was used. Conclusion. The use of terminal branches of the ECA (maxillary artery and proximal part of superficial temporal artery) expands the possibilities of cerebral revascularization performing in cases where low- or middle-flow EC–IC bypasses are required. The relatively rare use of these arteries in practice and few publications about these types of bypasses require careful selection of patients with preoperative assessment of the brachiocephalic arteries and hemodynamic parameters.