Microsurgical Anatomy Of The Anterior Inferior Cerebellar Artery And Clinic Value

Objective:1. To study the anatomy of anterior inferior cerebellar artery, therefore provide anatomical bases for relevant operations;2.Mimicking surgical approaches to the internal acoustic meatus to describe operative approaches of the scope and compare differences of these operative approaches.3. To study the features&variations of normal AICAs and AICA aneurysms in DSA images, which will contribute to clinical treatments to AICA aneurysms.4. Study the anatomy of AICA-CN VII-CN VIII complex with the help of endoscopy, to provide anatomy evidence to the microvascular decompression surgery.5.Provide anatomy evidence of occipital artery-AICA bypass surgery.Methods:1.15formalin-fixed adult cadavers(30sides) with colorful silica gel injected in blood vessels will be dissected under microscopy. The diameter, courser, main branches, variation, edge of blood supply, anastomosis with PICA and SCA and the relationship with adjacent structures will be studied both under microscopy and endoscopy,2. Mimicking surgical approaches to internal acoustic meatus on the specimens, including middle fossa approach in10sides、translabyrinthine approach in10sides, retro-sigmoid approach in10sides. The Advantages and disadvantages of these approaches were evaluated.3.50cases of normal AICAs on DSA and13case of AICA aneurysms will be studied on AICAs’and aneurysms’features.4. The length and diameter of occipital artery will be meatured, Occipital-AICA bypass will be mimicked.Results:1. AICA originates from the lower third of the basilar artery, usually as a single trunk, and encircles the pons near the abducent, facia, and vestibulocochlear nerve. After coursing near and sending branches to the nerves entering the acoustic meatus and to the choroid plexus protruding from the foramen of Luschka, it passes around the flocculus on the middle cerebellar peduncle to supply the lips of the cerebellopontine fissure and the petrosal surface.2. The middle fossa approach provide the great view of IAM without hurting the labyrinthine, and the hearing may be preserved. The TLA is the nearest route to the IAM and CPA, which provide the most widest view of the CPA, the facial nerve may be injured during the surgery, hearing can not be preserved using this approach. The RSA is easier to carry out, the IAM can be seen after drilling the bone of internal acoustic gate. The nerves can be easily be recognized after the exposure of IAM, besides it is especially convenient for the OA-AICA bypass.3.The origins, branches, courses and variations are observed in images of DSA, especially the anastomosis with PICAs and SCAs. AICA originates from BA in one or two or three trunks.6cases of AICA-PICA trunks were found. A strange case of AICA-EC was discovered. The anastomosis of AICA-PICA or AICA-SCA can not be seen very chearly on the DSA images. AICA aneurysms can be verified in size and appearance on DSA images.4. The length of occipital artery is79.32±5.22mm, while the range to AICA of CPA is55.24±6.32mm.Conclusion1. Normal and variable AICA have important significance on neurosurgery and endovascular therapy.2. The size and location of AICA aneurysm should be taken into consideration when choossing a surgical approach. Combine approaches are good for a complex one. Endovascular treatment is also a good idea for the aneurysm with right size and right location, especially for those who the vessel is involved in.3. When treating lesions of CPA inside or outside the IAM, Three surgical approaches can be chosen. The middle fossa approach provide the great view of IAM without injuring the labyrinthine, and the hearing may be preserved. The TLA is the nearest route to the IAM and CPA, which provide the most widest view of the CPA, the facial nerve may be injured during the surgery, hearing can not be preserved drring this approach. The RSA is easier to be carried out and the IAM can be seen after drilling the bone of internal acoustic gate. The nerves can be easily recognized after the exposure of IAM.4. The AICA can be sacrificed in surgery for giant aneurysms and tumors under certain conditions. The BOT test is suggested.5. The revascularization of AICA is rare, the occipital artery would be the best donor artery and PICA can be suitable in some cases.6. With assistance of endoscopy, exposure of CPA increased without increasing the traction of cerebellum. With the help of endoscopy, the neurovascular complex can be seen very clearly. The endoscopy will play an important role in surgeries of tumors and MVD.