Warren Frank M, Balachandran Ramya, Fitzpatrick J Michael, Labadie Robert F
Division of Otolaryngology, Head and Neck Surgery, University of Utah, Salt Lake City, Utah, USA.
Otol Neurotol. 2007 Apr;28(3):325-9. doi: 10.1097/01.mao.0000253287.86737.2e.
Percutaneous cochlear access can be performed using bone-mounted drill guides that are custom made on the basis of preintervention computed tomographic scans.
We have previously demonstrated the ability to use image guidance based on fiducial markers to obtain percutaneous cochlear access in vitro. A simpler approach that has far less room for application error is to constrict the path of the drill to pass in a predetermined trajectory using a drill guide.
Cadaveric temporal bone specimens (n = 8) were affixed with three bone-implanted fiducial markers. The temporal bone computed tomographic scans were obtained and used in planning a straight trajectory from the mastoid surface to the cochlea without violating the boundaries of the facial recess, namely, the chorda tympani, the incus buttress, and the facial nerve. These surgical plans were used to manufacture a customized drill guide by means of rapid prototyping (MicroTargeting Platform; FHC Inc.; Bowdoinham, ME, U.S.A.) that mounts onto anchor pins previously used to mount fiducial markers. The specimens then underwent traditional mastoidectomy with facial recess. The drill guide was mounted, and a 1-mm drill bit was passed through the guide across the mastoid and the facial recess. The course of the drill bit and its relationship to the boundaries of the facial recess were photographed and measured.
Eight cadaveric specimens were subjected to the study protocol. In seven of eight specimens, the drill bit trajectory was accurate; it passed from the lateral cortex to the lateral wall of the cochlea without compromise of any critical structures. In one specimen, the access to the middle ear was achieved, but the incus was hit by the drill. The average shortest distance +/- standard deviation from the edge of the drill bit to the boundaries of the facial recess was 0.78 +/- 0.56 mm (chorda tympani), 2.00 +/- 1.06 mm (incus buttress), and 1.27 +/- 0.54 mm (facial nerve).
Our study demonstrates the ability to obtain percutaneous cochlear access in vitro using customized drill guides manufactured on the basis of preintervention radiographic studies.
可以使用基于干预前计算机断层扫描定制的骨固定钻孔导向器进行经皮耳蜗入路。
我们之前已经证明了在体外使用基于基准标记的图像引导来获得经皮耳蜗入路的能力。一种更简单且应用误差空间小得多的方法是使用钻孔导向器将钻头的路径限制在预定轨迹内。
将8个尸体颞骨标本用3个骨植入基准标记固定。获取颞骨计算机断层扫描图像，并用于规划从乳突表面到耳蜗的直线轨迹，同时不侵犯面神经隐窝的边界，即鼓索、砧骨支柱和面神经。这些手术计划用于通过快速成型（MicroTargeting平台；FHC公司；美国缅因州鲍登汉姆）制造定制的钻孔导向器，该导向器安装在先前用于安装基准标记的锚定销上。然后对标本进行传统的乳突切除术并打开面神经隐窝。安装钻孔导向器，将1毫米的钻头穿过导向器，穿过乳突和面神经隐窝。拍摄并测量钻头的路径及其与面神经隐窝边界的关系。
8个尸体标本接受了研究方案。在8个标本中的7个中，钻头轨迹准确；它从外侧皮质穿过到耳蜗外侧壁，未损伤任何关键结构。在1个标本中，成功进入中耳，但钻头碰到了砧骨。从钻头边缘到面神经隐窝边界的平均最短距离±标准差为0.78±0.56毫米（鼓索）、2.00±1.06毫米（砧骨支柱）和1.27±0.54毫米（面神经）。
我们的研究表明，使用基于干预前影像学研究制造的定制钻孔导向器，能够在体外获得经皮耳蜗入路。
