Microscopic Anatomic And Clinical Application Of The Transcerebellomedullary Fissure Approach

Objective To investigate transcerebellomedullary fissure approach to the fourthventricle and provide anatomic bases to utilize the approach, and screening the bestapproach on the basis of the anatomical study. To investigate the therapeutic effect ofthe fourth ventricle tumors through the transcerebellomedullary fissure approachunder endoscope.Methods six cadaver heads fixed with fomalin and with the arteries and veinsperfused with color latex were used to expose and investigate the cerebellomedullaryfissure and its adjacent tissue via microscope. In the clinical application, clinicaldata of14cases with the fourth ventricle lesions were analyzed retrospectively. Allthe patients were treated by lateral wall type of the transcerebellomedullary fissureapproach, the endoscope was used if the lesions develop to the aqueduct and hard tobe exposed. Both Neurophysiological monitoring and Intraoperative Ultrasound wereused regularly.Results Cerebellomedullary fissure is a natural anatomical crevice between thecerebellar tonsil,biventral lobule and medulla oblongata; Three kinds of the approachcan deal with the tumor in different sector of the fourth ventricle;Posterior mediansulcus、terminal sulcus、medial eminence、facial colliculus、hypoglossal triangle andvagal triangle can be used to identification in operation; The posterior inferiorcerebellar artery and its branches take an significant role in the cerebellomedullaryfissure, it is easier to control bleeding because of the early exposure of posteriorinferior cerebellar artery. Lateral wall type of the transcerebellomedullary fissure approach can avoid time consuming and surgical damage in the three kinds of thecerebellomedullary fissure approach, the shortage of the lateral wall type of thetranscerebellomedullary fissure approach was below the mark of the exposure. In theclinical application, total surgical resection was achieved in12cases, gross totalresection in1, and partial removal in1. All the patients were diagnosed inpostoperative histopathology. Among the14cases,4of them were medulloblastoma,3epidermoid cyst,2ependymoma,2hemangioblastoma,1meningioma,1cavernoushemangioma and1astrocytoma. Normal cerebrospinal fluid cycle were recuperativein all cases, None aggravate of preoperative symptoms and none nuclei injury relatedcomplication have been found. Hypopnea occurred immediate after operation in onepatient, ventilatory support was performed by Ventilator, and the respiration wasrestored1day after the operation.Conclusions Transcerebellomedullary fissure approach can provide a better viewthan the previous approaches in terms of exposure of the ventricular walls sufficientlyand also avoid splitting the vermis which causes “cerebellar mutism”. Lateral walltype of the transcerebellomedullary fissure approach under endoscope, can handlemost of the fourth ventricle tumors, and can avoid time consuming and surgicaldamage of the extensive opening approach. The usage of Neurophysiologicalmonitoring and Intraoperative Ultrasound can degrade the surgical relatedcomplications such as facial palsy and amblyacousia.