A Clinico-Radiological Study: Veria Technique of Cochlear Implant-A Study of 50 Cases.

Abstract

Main limitation of classical technique is limited access to cochlea in terms of cochlear rotations and related structures, thus causing difficulty in electrode insertion. Veria technique allows full access to cochlea after raising tympanomeatal flap. To our best knowledge this is first clinic-radiological study for Veria technique studying distance between tympanic segment of facial nerve and posterior wall of external auditory canal (EAC) demonstrating facial nerve safety. Prospective study was done on 50 patients having bilateral sensori-neural hearing loss. Patients underwent cochlear implant surgery irrespective of age and gender. Preoperative high-resolution computed tomography temporal bone and magnetic resonance imaging head was done, distance between tympanic segment of facial nerve and posterior wall of EAC and basal turn angle were measured. Intraoperative NRT followed by orbito-meatal X-ray was done in post operative period. 25 (50%) were male, 25 (50%) female. 35 patients (70%) showed that the distance between tympanic segment of facial nerve and posterior wall of EAC was more than 3mm with mean 4.41mm (± 0.63 SD). Distance calculated was greater in older age group than younger group. Patient having inner ear malformation, mean was 3.96mm (± .44 SD). Whereas patients having acquired disease, mean distance was 4.30mm (± .47 SD). On gender comparison of basal turn angle score, no significant difference was observed male (54.34° ± 4.48°) versus female (55.66° ± 4.15°) (p = 0.282). Mean of basal turn angle (BTA) in ≤ 5years age group was 54.89° ± 3.65°, in 6-10years age group was 55.21° ± 5.23° and in age group ≥ 11years was 54.93° ± 4° with no significant difference in mean value between the groups (p = 0.282). High jugular bulb was seen in 4 patients (2 in right side, 2 in left side), hypoplastic jugular bulb was seen in 10 patients (9 in left, 1 in right), otosclerosis in 2 patients. Veria technique is safe for facial nerve, as preoperatively distance between tympanic segment of facial nerve and posterior canal wall can be identified. It is suitable method for rotated cochlea (identified preoperatively through BTA) and deformed cochlea as it offers a wide visibility and accessibility as compared to posterior tympanotomy approach. BTA and distance between posterior canal wall of EAC and tympanic segment of facial nerve should be done in all cases to see any cochlear rotation and feasibility of surgery.