| Surgery of the skull base is one of the most challenging and active field of modern Neurosurgery. To relieve the severe distraction of the brain, gain well exposure, shorten the distance to the lesion, amelioration the illumination of the deep part, amplification the operation area and reach the part that couldn't reach in the classical approaches, people created kinds of skull base approaches which also had many shortcomings such as added trauma and exposure of normal brain tissues, prolonged operation procedure. Endoscope-assisted keyhole approach which is the product of the progress of modern microneurosurgery and science and technology has applied in clinical practice of skull base surgery and is being accepted by more and more neurosurgeons. The window of the skull in keyhole approaches is much smaller than in the classical approaches, the image under the endoscope is different from what under the microscope and the approach can offer a direct access to the lesion. The anatomy of the keyhole approach is different from what in the classical approach, thus being familiar with the anatomy, the exposure scope and the work scope of the keyhole approaches is important to carry out keyhole surgery in clinical practice. Objective:To study the relationship of vital anatomic structures in supraorbital and subtemporal keyhole approach, discuss the exposure scope and the manipulation scope and offer clinical surgeons anatomic basis of the approaches, discuss the possibility to treat kinds of lesions in the skull base through keyhole approaches. Methods:The studies were divided into two parts: Clinical anatomy study of supraorbital keyhole approach and subtemporal keyhole approach. We firstly carried out identification of anatomic landmarks and measurement of their relationship of location in 21 adult cadaver heads fixed in formalin. The Calvarium was sawed along the linea from glabella to external occipital protuperance. Cut off the brain stem at the level of tentorium cerebelli and took out of the telencephalon, the diencephalon and part of the mesencephalon. (l)Observe the locating relationship of the optic chiasma and the tuberculum sellae; measure the area of the first space, the length of the intracranial part of the optic nerve, the length of the supraclinoid part of the internal carotid artery(from extra-cavernous sinus to the posterior communicating artery); Measure the distance from the zygomatic process and the supraorbital foraman to the cecum foraman, the skull aperture of ipsilateral and contralateral optic canal, the ipsilateral and contralateral anterior clinoid process ,the ipsilateral and contralateral post clinoid process; Measure the angle between the line from the zygomatic process or the supraorbital foraman to the marks and the midline. (2)Measure the distance between the foramen rotundum, the foramen ovale, the foramen spinosum, the trigeminal nerve impression, the arcuate eminence or the greater petrosal hiatus to the superior margin of zygomatic arch at temporomandibular joint and the midline; measure the length of each edge of the Kawase triangle and Day rhombus and calculate the area. Secondly, we simulate endoscope-assisted supraorbital keyhole approach and subtemporal keyhole approach in 9 freshadult cadaver heads to treat lesions in the skull base and definite their exposure scope and the manipulation scope; techniques to increase the exposure scope and the work scope were tried. Results:1 Results measured in the 21 adult cadaver heads fixed in formalin1.1 The distance from the zygomatic process and the supraorbital foraman to the cecum foraman, the skull aperture of ipsilateral and contralateral optic canal, the ipsilateral and contralateral anterior clinoid process ,the ipsilateral and contralateral post clinoid process were respectively(50.1 ±2.l)mm and (27.5±3.2)mm, (51.5±3.1)mm and (45.2±3.6)mm, (86.5±0.9)mm and (57.1±1.9)mm, (53.1±3.0)mm and (59.0±2.1)mm, (89.0±2.5)mm and (62.8±1.5)mm, (61.5±1.7)mm and (92.1±3.6)mm, (73.6±l.l)mm and (95.6... |
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