Anatomical study on the MVD approach for hemifacial spasm and the middle neurovascular complex

Objective To investigate the anatomical study of mierovascular decompression (MVD) for bemifacial spasm via the translateral suboccipital infrafloccular approach and the middle neurovascular complex. Methods A total of 15 adult cadaver heads fixed in 10% formalin were used for this study.Ten of them were perfused with red latex through artery and blue latex through vein,to facilitate their definition.The heads were placed in a head holder in a position simulating the translateral suboccipital infralloccular approach to the cerebellopontine angle (CPA) region.Dissections were performed under 4 to 25 magnification.Special attention was given to the microanatomy related to the middle neurovascular complex in the CPA region.At the same time, 9 patients with hemifacial spasm were treated via translateral suboccipital infrafloccular approach.Results Via translateral suboccipital infrafloccular approach,with gentle retraction of the flocculus in a caudorostral direction perpendicular to the vestibulocochlear nerve,the root exit zone of the facial nerve could be easily observed medial to the root zone of vestibulocochlear nerves in the supraolivary.Conclusion The greatest advantage of trans- lateral suboccipital infrafloccular approach lies in reaching the middle neurovascular complex in the CPA accurately with minimal risk of postoperative cranial nerve palsy.