The objective of the present study was to improve the effectiveness of cochlear implantation (CI) in the patients presenting with cochlear-vestibular abnormalities based on the development and practical application of the algorithm for the insertion of an electrode arrayinto the spiral (Rosenthal’s) canal of the cochlea taking into consideration the specific anatomical features of the middle and inner ears. The study included 25 patients with congenital malformations of the inner ear and bilateral grade IV sensorineural loss of hearing or deafness selected for CI. Indications for drilling a cochleostomy were the high localizationof the jugular bulb and the absence of its bone wall (5 patients, 20%). In the remaining cases, it proved possible to identify the round window and perform the transmembrane insertion of the active electrode. In 15 (69%) patients, the surgical intervention provoked intraoperative leakage of the cerebrospinal fluid that was successfully stopped by the careful tamponade of either the cochleostoma or the round window niche with the use of an automuscular flap. Taken together, good visualization of the round window and the transmembrane insertion of the active electrode into the spiral (Rosenthal’s) canal of the cochlea in the patients presenting with cochlear-vestibular abnormalities made it possible to reduce to a minimum the injury to the spiral organ of the cochlea, control liquorrhea, and improve auditory performance in the postoperative period.