Anatomical Study And Clinical Application Of Kawase Approach For Resection Of Petroclival Tumors

Objective The anatomical position of the petroclival region is deep,and it is adjacent to many important structures such as nerves,blood vessels,and brainstem.Therefore,the operation of tumors in this region has always been a major difficulty in neurosurgery.Kawase approach,that is,the inferior temporal approach through the anterior petrosal bone。this approach can better handle the ventral brainstem and petroclival lesions by removing the bone at the petrosal apex of the temporal bone and increasing the exposure of the petroclival area.The purpose of this paper is to quantify the important structures and related positional relationships of the petroclival region,and to provide an anatomical basis for the safe and accurate removal of the petrosal apex bone in clinical operations.Methods Select 5 dry skull base specimens（10 sides）,observe and identify the greater superficial petrosal nerve groove,arcuate eminence,internal auditory meatus,foramen spinous and other bony structures around the petrous bone,and use a drill to remove the bone at the tip of the petrous bone to expose the cochlea,internal carotid artery meatus,internal auditory canal floor,bone semicircular canal and other structures,observe and measure the positional relationship and distance of each structure;Take 5adult wet head specimens（10 sides）,open the skull with a craniotomy instrument from the upper edge of the eyebrow arch to the upper edge of the external occipital carina,remove the cerebral hemisphere and diencephalon,and preserve the cerebellum,brain stem and tentorium,Use microscope to observe and identify anatomical landmarks such as greater superficial petrosal nerve hiatus,arcuate eminence,petrosal ridge,the greater superficial petrosal nerve,trigeminal nerve,Gradually remove the petrosal tip bone to expose the internal carotid artery,cochlea,and geniculate ganglion in the petrosal bone,measure the distances between many structures and record the data;Take4 wet head specimens（8 sides）soaked in 10% formalin and perfused with latex,Simulate the surgical process of the Kawase approach under the observation of a Zeiss microscope,and conduct anatomical observation of the relevant structures during the operation,Use vernier calipers and compasses to measure the distances between structures three times,take the average value,use statistical methods to analyze the data,and finally summarize and analyze the surgical operation and measurement data.Results 1.The triangle of Kawase is the area bounded by the arcuate eminence,the greater superficial petrosal nerve,and the trigeminal nerve indentation,There are foramen spinous and foramen ovale on the anterolateral side of this triangle,and structures such as cochlea,geniculate ganglion,greater superficial petrosal nerve and petrosal internal carotid artery on the lateral side,there are arcuate bulge,bony semicircular canal,internal auditory meatus and facial nerve and other structures on the posterolateral side,the anteromedial triangle is the main area for petrous bone removal in the Kawase approach.2.Among the 28 samples in this group of experiments,16 cases showed obvious arcuate bulge,and the remaining 12 cases were relatively flat or not obvious;Among the 8 dry skull specimens,the superior semicircular canal was located below the arc apex of the arcuate eminence in 5 cases,and the superior semicircular canal was located inside the arc apex in 3 cases.3.The horizontal segment of the internal carotid artery is 9.88±1.37 mm away from the petrosal ridge,removing the bone at the petrosal apex within this range can avoid damage to the internal carotid artery.4.The anterior and posterior diameters and the upper and lower diameters of the internal auditory canal were 7.27±1.31 mm and 4.17±0.41 mm,respectively,and the internal auditory meatus length was 8.18±0.40 mm.5.Observable range after petrosectomy:Anteriorly to the posterolateral aspect of the cavernous sinus,posteriorly to the anterior wall of the internal auditory meatus,laterally to the greater superficial petrosal nerve and internal carotid artery,and down to the inferior petrosal sinus.Conclusion 1.The foramen spinous,the greater superficial petrosal nerve,mandibular nerve and other structures in the petrosal part of the temporal bone are important anatomical landmarks in the Kawase approach,and other structures in the petrosal region can be located according to them.2.The anatomical variation of the arcuate eminence is large,and it is not appropriate to use the arcuate eminence to locate the superior semicircular canal.3.Summarized a new method of locating the cochlea and internal auditory meatus.4.Proficiency in the microanatomy of the petrosal region,quantifying the positional relationship between the anatomical structures of the petrosal temporal bone,It provides a reliable anatomical basis for removing the petrosal apex bone and expanding the exposure range of the petroclival area in the Kawase approach.