人工耳蜗颅中窝进路植入点

目的:探讨人工耳蜗植入颅中窝进路植入点的精确定位及其可行性。方法:成人整颅标本行植入点定位,并对相关测量项进行测定,然后确定植入点的精确定位;通过1例成人女性尸头标本行模拟手术,验证其可行性。结果:沿岩浅大神经延长线,在距面神经裂孔3.10 mm±0.88 mm处确定"O"点("O"点位于膝状神经节窝),再以"O"点为原点,确定与岩浅大神经夹角为97.85°±5.38°的面神经管迷路段内侧壁投影线,然后依据面神经管迷路段内侧壁投影线做距其1.58mm±0.41mm的平行线,后再做距岩浅大神经5.47 mm±0.95 mm的平行线,两平行线相交点即为植入点("Z"点)。植入点与面神经沟的距离仅为0.67mm±0.15mm,最小值甚至为0.00 mm,而面神经沟的下部即蜗神经管,并且蜗神经管比面神经沟更为凸前,在植入点开窗极易损伤蜗神经起始段。通过模拟手术验证,用以上植入点确定方法,行开窗,不能保证进入耳蜗底转上部,更不能保证准确进入前庭阶,并有损伤蜗神经的可能。结论:颅中窝进路人工耳蜗植入点选择,不能在不磨除颞骨岩面骨质的情况下行精确定位。手术时应以面神经裂孔为定位点,先确定岩浅大神经与面神经管迷路段内侧壁投影线,然后磨除距两者1.00 mm平行线夹角内区域的骨质,尽量轮廓出耳蜗底转上部,颜色呈蓝线时,靠蓝线后部行植入点定位开窗,这样既可以将电极准确植入耳蜗底转,又可以因不暴露岩浅大神经管内段和面神经迷路段,避免其损伤。

Implant point of cochlear implantation via the middle cranial fossa approach

Objective:To study the accuracy and feasibility of implant point of cochlear implantation via the middle cranial fossa approach.Methods:Adult skull specimens were determined by measuring related items and a simulated surgery was performed to verify its feasibility on one adult female cadaver.Results:"O" point located 3.10 mm±0.88 mm from the facial nerve crack on the extension of greater superficial petrosal nerve,was defined as the origin to find facial nerve tube fan sections of the medial wall of the projection which made an angle of 97.85°± 5.38° from the greater superficial petrosal nerve.Where the two paralleling lines to the facial nerve tube fan sections of the medial wall of the projection at a distance of 1.58 mm±0.41 mm and the two paralleling lines that the greater superficial petrosal nerve at a distance of 5.47 mm±0.95 mm met,was defined as the implant point ("Z").Cochlear nerve canal was below the facial nerve groove 0.67 mm±0.15 mm (even 0.00 mm) away from Z point.In addition to the facial nerve groove more convex,primary section of cochlear nerve was easily damaged when fenestrated point was located at Z point.The simulated surgery with the data of specimens showed that fenestration in the above-mentioned method failed in entering the upper portion of cochlear basal turn and scalavestibule,and possibly damaged the cochlear nerve.Conclusion:It's difficult to locate the implant point of cochlear implantation via the middle cranial fossa approach when the petrosal bone was artificially grounded.The projection lines of the greater superficial petrosal nerve and the facial nerve tube fan sections of the medial wall should be first identified by the anchor point as facial nerve hiatus.The region gets blue after grinding the bone 1.00 mrn within both parallel lines for outlining the basal turn of the cochlea upper.And then implant point for fenestration is positioned on the posterior of blue region to precisely implant the electrode into basal turn and minimize the damage for not exposing canal segment of greater petrosal nerve and labyrinthine segment of canals facialis.