The Microanatomic Study On Anterior Approaches To The Central Skull Base

ObjectivesThe central skull base which refers to the area of sella turcica and occipital clivus locates at the deep position of the skull base, containing many important and complex tissues, nerves, and blood vessels that enter or exit the cranial cavity. However, it is difficult to remove the lesions of this area totally and totally removing always leads to serve postoperative comph'cations. So it is necessary to consider the common features and differences of the lesions comprehensively and choose the appropriate operative approaches preoperatively. In clinical practice, anterior lateral approaches, posterior lateral approaches and anterior approaches are suggested to deal with the lesions of the central skull base. Neurosurgeons are familiar with the anterior lateral approaches and the posterior lateral approaches that are suit for dealing with the lesions which grow toward lateral orientation. Anterior approaches have the advantage of exposing and reaching the lesions which locate in the central skull base, especially the epidural lesions in the middle line. However, no systemic microanatomic studies on anterior approaches to the central skull base are available at present. In order to provide detailed parameters of anatomic structures and direct illustrations of microanatomic structures of the central skull base for clinical operations, to deal with the problems related to the anterior'approaches, importantly, to improve the operative effects of lesions of the central skull base, we designed and carried out this study.Methods15 cadaveric heads of Chinese adults fixed by 10 % formalin, age and sexcouldn't be exactly judged. In order to maintain the caliber of blood vessels normally and improve the quality of photos , red latex was injected into arterial systems and blue latex was injected into venous systems. 15 dry skulls of Chinese adults were used to observe and measure the osseous structures. Both extended transfrontal approach and extended transsphenoidal approach were mimicked on each specimen after being studied on the imaging of CT scanning and three - dimensional reconstruction, with the help of operative microscope, all specimens were dissected layer by layer according to the operative approaches. Referring to the imaging anatomy of three - dimensional reconstruction, we measured the anatomic structures accurately and took photos of the microanatomic structures. All datas were statistically processed and presented in the means ( range of measured values) style.ResultsThe results contained the detailed parameters of anatomic structures related to anterior approaches and the direct illustrations of microanatomic structures of the central skull base. Distance between the osseous landmarks, thickness of osseous structures of important parts were measured, the maximum extent of osseous structures that could be drilled away during the process of mimicking operations were explored. Extended transfrontal approach could well expose and easily reach the area of sella turcica and occipital clivus. The more important extracra-nial structures involved the supraorbital nerves and blood vessels. The micro-anatomy of intracranial subdural structures involved olfactory cistern, chiasmic cistern, internal carotid cistern, terminal lamina cistern, sylvian fissure cistern, peduncular cistern, ambient cistern. Each cistern was measured and depicted on site, size and shape. Tissues, nerves and blood vessels of each cistern were dissected with microsurgical procedures. Photos of these structures pre or post being dissected were obtained. Extended transsphenoidal approach could well expose and easily reach the area of the central skull base either. Intracranial mi-croanatomic strutures related to extended transsphenoidal approach involved pre-pontine cistern, interpeduncular cistern, cerebellopontine angle cistern. The length, width, depth of each cistern were measured, site and shape were depic-ted, contains of each cistern were dissected just like the extended transfrontal approach. The values...