Microanatomy of intracranial segment of vertebral artery and its main branches in surgery adopt far lateral approach

Abstract

Objective To discuss how to protect the intracranial vertebral artery and posterior inferior cerebellar artery by observing and measuring the intracranial vertebral artery in the surgery adopt far lateral approach. Methods Mimicking far lateral approach, 20 adult cadaveric heads connected to neck fixed with 10% formalin were dissected. Intracranial segment of the vertebral arteries and their main branches were exposed and measured under operating microscope. Results The intracranial vertebral artery joined with the contralateral one into the basilar artery after traveling through the atlanto-occipital sulcus. The relationship between the vertebral artery and the hypoglossal nerve is close. Thirty sides (75%) of the vertebral arteries traveled to pons medulla sulcus in front of the hypoglossal nerve roots and 2 sides (5%) behind the hypoglossal nerve roots, while 8 sides (20%) traveled among the hypoglossal nerve roots; 70% of the vertebral arteries were contacted to the hypoglossal nerve roots, 30% of which compressed the hypoglossal nerve. The main branches of intracranial segment of the vertebral arteries were the posterior inferior cerebellar arteries, the anterior spinal arteries, the posterior meningeal arteries,and some perforating arteries. Posterior inferior cerebellar arteries all originated from the intracranial vertebral artery were the largest vertebral artery's branches; their trip was mostly loop-shaped and they had close relationship with Ⅸ, Ⅹ, Ⅺ cranial nerves. The starting points of the posterior inferior cerebellar arteries were different, even in the same specimen, but most of them originated from the upper 1/3intracranial vertebral artery. No anterior inferior cerebellar artery was noted originated from the vertebral artery in our specimen. Anterior spinal arteries originated from the vertebral arteries joined with the branches of the bilateral vertebral arteries and traveled down through the tortuous anterior median fissure to supply the spinal cord. Conclusion Being familiar with the characteristics and anatomic vertebral arteries variations of the intracranial vertebral artery and its branches can contribute to identify and protect the intracranial segment of the vertebral artery and its main branches in the surgery adopt far-lateral approach. Key words: Vertebral artery; Posterior inferior cerebellar artery; Far lateral approach; Jugular foramen region; Microsurgical anatomy