Surgical Microanatomy Of The Dura Mater Space And Petrous Apex Approach With Neuronavigator-Guided

Part I The Microanatomy of the Structures Related to theSphenopetroclival Region Objective: To study the surgical microanatomy of thesphenopetroclival region so as to provide the detailed parameters for the sphenopetroclival approach, which is precise-orientation and less-invasion . Methods: The microsurgical dissections were performed on formalin-fixed and dye-injected cadaveric heads with the aid of an operating microscope to observe and measure the dura, nerves and vessels in the sphenopetroclival region, and to learn the relationships among the dura, nerves and vessels in the sphenopetroclival region with histochemical technique. Results: In middle cranial fossa, cranial nerves IIL IV and VI, which were enwrapped by arachnoid and dura, entered between the dura of middle cranial fossa. The Meckel 's cave, the trigeminal ganglion and its three branchs, just like a glove, were embedded between the dura of middle cranial fossa , and ICA and some venous structures traveled among them. Cavernous sinus and those structures were located in a cave made up of two floors of the middle cranial fossa dura, namely dura mater space which was divided into three parts by the neuro-midriff: a. The dura fissure: the outer part by which the extradural approach can performed without the separation of trigeminal nerve branches; b. The blood fissure (the cavernous sinus); c. The clinoid process fissure: located between the anterior clinoid process and the dural plate. Conclusion: After the study of the microsurgical anatomy of sellar region we suggest a new constructive conception about this region whichis the surgical anatomy based by the sphenopetroclival approach. We think that two floors of dura mater are separated along the line medial to the parasellar, superior orbital fissure, rotundum foramen, oval foramen and form the dura mater space which was divided into three parts by the neuro-midriff. Through those space the structures in the cavernous sinus can be well exposed, and even with the maximal petrosal bone resection, the enlarged exposure includes petrous apex, the CPA, the upper clivus. There are several advantages of this approach: extradural manipulation, less retraction of brian tissue, avoidance of the temporal drainage damages, and lower incidence of postoperative complications.