Pritz M B
Division of Neurological Surgery, California College of Medicine, University of California Irvine Medical Center, Orange.
Acta Neurochir (Wien). 1991;113(1-2):74-81. doi: 10.1007/BF01402118.
Tumours located anterior to the cervicomedullary junction have been most commonly approached via one of two routes: anterior/transoral or posterolateral. Each of these surgical corridors can pose potential pitfalls. To circumvent these problems, a lateral suboccipital approach in conjunction with an upper cervical hemilaminectomy has been used. Selecting an appropriate surgical corridor between the lower cranial nerves (IX through XII), the vertebral artery, and the posterior inferior cerebellar artery has allowed satisfactory tumour removal. A three-dimensional picture of tumour location and relationship to surrounding neural and vascular structures is obtained preoperatively from computed tomography and magnetic resonance. Arteriography is essential to determine the origin, course, and relation of each vertebral to the tumour as well as the contribution of each vertebral to the basilar. In instances of abnormalities in the posterior circulation, evaluation of the carotid contribution to the basilar is crucial. The advantages of this approach are several. First, a direct view of the anterior surface of the lower brainstem und upper cervical cord is obtained. Second, surgery is undertaken in a sterile field in which the dura can be closed watertight. Third, neither mastoidectomy nor transposition of the vertebral artery is required. The major difficulty is the necessity to operate through narrow surgical corridors bounded by the lower cranial nerves, vertebral and posterior inferior cerebellar arteries, and the lower medulla and upper cervical cord. These structures provide the major obstacles to dissection as well as the primary causes of morbidity.
位于延髓颈髓交界处前方的肿瘤，最常用的手术入路有两种：前路/经口入路或后外侧入路。这些手术通道都可能存在潜在的陷阱。为了规避这些问题，已采用枕下外侧入路联合上颈椎半椎板切除术。在较低的颅神经（IX至XII）、椎动脉和小脑后下动脉之间选择合适的手术通道，已能实现满意的肿瘤切除。术前通过计算机断层扫描和磁共振成像可获得肿瘤位置及其与周围神经和血管结构关系的三维图像。血管造影对于确定每条椎动脉的起源、走行及其与肿瘤的关系，以及每条椎动脉对基底动脉的供血情况至关重要。在后循环异常的情况下，评估颈动脉对基底动脉的供血情况至关重要。这种入路有几个优点。首先，可以直接观察到下脑干和上颈髓的前表面。其次，手术是在一个无菌区域进行的，硬脑膜可以严密缝合。第三，既不需要进行乳突切除术，也不需要对椎动脉进行移位。主要困难在于需要通过由较低的颅神经、椎动脉和小脑后下动脉以及延髓下部和上颈髓所界定的狭窄手术通道进行操作。这些结构既是解剖的主要障碍，也是发病的主要原因。
