The senior neuro-otologist (DÜT) of the study team carried out all dissections using a micromotor (Bien Air Surgery SA, le Noirmont, Switzerland, handpiece length: 70, 95, and 125 mm, burr diameter: minimum 0.6 mm). With the help of an endoscope (Karl Storz Gmbh & Co., Tüttlingen, Germany, length: 18 cm, degree: 0°, 30°, and 70°, diameter: 2.7 and 4 mm) and microscope (Carl Zeiss f170, Carl Zeiss Meditec AG, Oberkochen, Germany), the dissections from the external auditory canal to the cochlear promontory were performed to determine the spatial relationship of TN with RWN and OW. The steps were summarized for each ear as follows: (a) the head was positioned according to otologic surgery, (b) the skin near the external auditory canal was cut with a circumferential incision, (c) the auricle was retracted anteriorly, (d) the skin of external auditory canal, tympanic membrane, chorda tympani, malleus, and incus were removed, (e) a wide canalplasty was done, (f) after cutting the stapedial tendon, the stapes pulled carefully out using a surgical hook, (g) finally, TN, RWN, and OW were exposed, and (h) from the same position and distance, the cochlear promontory was photographed with a millimeter scale using the microscope camera (Nikon d3300 digital camera, Nikon, Tokyo, Japan).