| Objective The purpose of this study is to describe and anatomically analyze the operating spaces provided by the subtemporal keyhole approach, and offer the technique of the approach to clinical application.Methods (l)Anatomic Anatomic features were studied in 30 sides of adult embalmed cadaveric heads perfused with colored silicone, using operating microscope and neuroendoscope. The head is placed supine and rotated contralaterally to the side of the trepanation, that keep the zygomatic arch horizontal to the floor. A vertical or arc linear epifascial skin incision approximately 5 cm is created from the point at the inferior rim of the zygomatic arch approximately 1 cm anterior to the external auditory meatus. After the skin is retracted bilaterally,the temporal muscle fascia is incised in a reverse Y-shaped fashion, with the basal leaflet reflecte caudally over the zygomatic arch, the lower border of the temporal muscle is the retracted upward .then the squamous bone can be exposured. Drill a hole at the superior of the posterior pedicle of the zygomatic arch. An oval-shaped craniotomy superior and anterior to the point , approximately 2.0 cm to 2.5 cm in width and 2.0 cm in height is performed close to the cranial base. Additional shaving of the superior rim of the zygomatic arch further facilitates the upward viewing angle.Firstly beginning the intradural procedure after the craniotomy, analyze the operating spaces provided by the approach and measure the important datas of the main anatomic structure. Then beginning the extradural procedure, in this procedure, sometime should resection the bone bridge of the middle base of skull and be performed as far extradurally as possible to keep anatomiclandmarks in sight for better orientation and to preserve the dural membrane for later reconstruction.The resection of the petrous apex is required in order to exposure the petroclival region lower than the Vth cranial nerve. The bony resection is limited by greater superficial petrosal nerve, arcuate eminence and mandibular nerve. To approach the midclivus, further anterior bony resection can be expand to beyond the trigeminal impression and some area beyond the mandibular nerve. Analyze the operating spaces of provided by the extradural procedure and measure the important data of the main anatomic structure. (2) Clinic The technique was used in eight interventions patients during the period of October 2002 to December 2004, the indications for surgery were based on the position, pathology and size of the lesions. 6 males and 2 females, aged from 41 to 58 years old. Among these lesions, five are meningiomas on tentorium of cerebellum, Two are cholesteatomas in the different place in cranial at the same time, one is meningioma on upper petroclival region, The diameter of the lesions range from 65 mm to 35 mm.Results (\)Anatomic The cadaveric study provided intimate experience with the microsurgical anatomy of the approach. When procedure from the intradural, the neurovascular structures of the suprasellar, petroclival, interpeduncular cistern and prepontine cistern can be well exposured without traumatization. The ventral - lateral pontine can also be well exposured. When procedure from the extradural, The neurovascular structures of the lateral wall of the lateral sellar compartment (LSC) can be well exposed without traumatization ; The operating spaces of the lateral wall of the LSC can be exposed sufficiently, they are lateromedial triangle, Parkinson's triangle ,Mullan triangle, lateral triangle,Glasscock triangle, Kawase triangle and some part of anteromedial triangle in superior wall of the LSC ; The cerebello pontine angle (CPA) can also be well exposured, with resection the bony over the internal auditory meatus. The area of the resection of the petrous apex can be extended anteriorly under... |
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