Sense of taste in patients after cochlear implantation-preliminary study

Background: Taste is the leading sense in how we determine the quality of consumed food. Proper gustatory sensation largely determines the well-being and health of an organism, and this affects their quality of life.Objectives: The aim of the present study was to estimate the risk of early taste disorders following implantation surgery. Methods: Twenty patients underwent a taste test before, 1 day after, and 1 month after cochlear implantation. The taste sensations of sweet, sour, salty, and bitter were determined. Results: Statistical analysis showed no significant differences (p > 0.05) between individual tests among the entire study group. After dividing the respondents into smoking (n=6) and non-smoking (n=14) groups, only a weak correlation (p =0.043) was found between the results of the first and second examination in the smoker group. However, a statistically significant decrease in the number of saline-sensitive (p<0.001) and acid-sensitive (p = 0.042) subjects was observed. Conclusion: These findings suggest that people after a cochlear implant may have transient taste disorders. Taste disorder called dysgeusia may be an early complication after the implantation procedure contributing to deterioration of patients quality of life. Keywords: Sense of taste; taste disorders; cochlear implant surgery; quality of life, partial deafness treatment.

The Age of Hesitancy, Recognition, Reinforcement, and Interposition in Cochlear Implant Children in Ahvaz, Iran: A 5-year Study

Background: Delay in early detecting of hearing loss (HL) and aural interposition in children have intense impacts on their speech and language expansion, academic progress, social skills, and psychological status. Objectives: The purpose of the current study was to assess the age of hesitancy, recognition, reinforcement, and interposition in children with bilateral severe to deep hearing loss. Methods: This cross-sectional study was conducted on children who were candidates for cochlear implant surgery at Khuzestan Cochlear Implantation Center, Ahvaz, Iran. The rehabilitative histories and children’s medical were utilized to record ages of hesitancy, recognition, reinforcement, and interposition for both groups of “high-risk” and “not-high-risk” children. Paired sample t-test was used to evaluate the middle ages of children between the “high-risk” and “not-high risk” groups. Results: A total of 389 children (205 boys and 184 girls) were included. The mean ages of hearing loss hesitancy, hearing loss recognition, fitting the hearing reinforcement devices, and interposition were 10.7 ± 7.1, 15.75 ± 9.4, 21.81 ± 8.1, and 26.32 ± 9.2 months, respectively. The average delays between the ages of hesitancy and recognition: 3.74 (P < 0.0001); recognition and reinforcement: 5.05 (P < 0.0001); reinforcement and interposition: 2.83 months (P < 0.0001) were obtained. There were no significant statistical differences in terms of four studied ages among the high-risk (n = 129) and not-high risk (n = 260) children (P > 0.05). Conclusions: The outcomes showed that there is a significant improvement in the average ages of hearing loss hesitancy, recognition, reinforcement, and interposition in Iran. However, there is still an obvious difference between these ages and those recommended by the Joint Committee on Infant Hearing.

Multicentre cohort study of cochlear implantation outcomes in Thailand

ObjectivesTo report the status and outcomes of cochlear implantation in Thailand.DesignCohort study.SettingTertiary care and university hospitals.ParticipantsPatients who underwent cochlear implant surgery in Thailand.InterventionsThis project collected data from all government and university hospitals in Thailand where cochlear implant surgery was performed between 2016 and 2020.Primary and secondary outcome measuresBaseline characteristics, operation data, complications, audiological outcomes and quality of life were reported.ResultsThis study included 458 patients, and nearly half of the patients were children and adolescents (46.94%). The mean age of the patients was 2.96±5.83 years. At 1 year postoperatively, the mean pure tone average of the hearing threshold in the implanted ear significantly improved from unaided preoperative baseline (mean difference (MD) 64.23 dB HL; 95% CI 59.81 to 68.65; p<0.001). The mean speech recognition threshold also improved (MD 55.96 dB HL; 95% CI 49.50 to 62.42, p<0.001). The quality-of-life scores of the EQ-5D-5L, PedsQL and HUI3 questionnaires at 1 year showed improved mobility (range, 0–5; MD 0.65; 95% CI 0.05 to 1.25; p=0.037), hearing (range, 0–6; MD 0.96; 95% CI 0.30 to 1.61; p=0.006) and speech (range, 0–5; MD 0.44; 95% CI 0.04 to 0.84; p=0.031). Common complications included electrode dislodgement (2.18%), vertigo (1.23%) and meningitis (1.93%).ConclusionsExcellent audiological outcomes and improvement in the quality of life in the mobility, hearing and speech domains were observed in patients who underwent cochlear implantation in Thailand.

Reliability of start and stop control of hydraulic actuation for the insertion of electrode arrays

Atraumatic insertions of electrode arrays (EA) into the cochlea aim to preserve natural structures and residual hearing. However, there is a limit as to how smooth and slow a surgeon can insert an EA. As a potential solution, we recently presented a tool (cochlea hydro drive, CHD) that makes use of an infusion pump to prompt and control the desired, continuous and very slow (< 1 mm/s) forward movement for such insertions. The present work further describes the onset, delay and cessation of the hydraulic actuation in response to different start and stop mechanisms, to better understand the safety of its application for cochlear implant surgery. Methods: Our previously designed tool was used to perform insertions of an EA into an artificial scala tympani model. The prototype is designed to hold an EA, which is then actuated by a standard infusion pump programmed to operate at 0.4 mm/ and 0.1 mm/s. A tubing system between the CHD and the pump includes a three-way valve. Ten insertions were operated using the functions of the pump and ten using the valve. Results: From the programmed start to the actual movement, we observed a larger average delay using the pump’s start function (5 s at 0.4 mm/s; 17 s at 0.1 mm/s) vs. opening the valve (< 0.7 s for both velocities). Moreover, the average cessation of movement with the valve closure was almost immediate (0.7 s for both velocities; this corresponds to < 0.1 mm with the slower tested velocity), as opposed to 60- 80 s delay when using the pump’s stop function. Conclusion: The use of a 3-way valve facilitates motion cessation to the high accuracy level required for cochlear implant surgery. These promising findings support future clinical translation of our tool.

Illustrating orientation changes of the insertion trajectory during cochlear implant electrode array insertion

Introduction: Recent investigations focused on the optimization of atraumatic cochlear implant surgery have highlighted the relevance of the electrode array (EA) insertion trajectory. This is particularly studied in the context of minimally-invasive “keyhole” and robotic-assisted approaches, e.g. to avoid injuring structures inside and outside the cochlea. However, little is known about the natural, manual movements and trajectory followed during the insertion process. The present work illustrates the orientation changes within the trajectory a surgeon follows during insertions of EAs into a human cadaveric cochlea. Methods: An EA insertion tool equipped with a gyroscope was developed in our laboratory. During the insertion trials, the gyroscope captures the tool’s spatial orientation. A human head specimen and a single EA were used to perform insertions into a cochlea. A cochlear implant surgeon performed all insertion trials. The recorded orientations were compared to the initial orientation upon cochlea entry to assess the surgeon’s range of motion by calculating the angle between orientation vectors. Results: Fifteen EA insertions were performed with a median maximal deviation from the initial orientation of 7.2° (5.3 -11.1°) across trials. The largest orientation changes were seen towards the last half of each insertion trial. A negative relationship between degree of axis change and number of insertion trial was observed (r = -0.5). Conclusion: Manual EA insertions into a cadaveric cochlea revealed an insertion trajectory with maximum orientation changes of approximately < 10° degrees. The observed trend on decreasing range of motion with increasing number of insertion trials may be attributed to surgeon’s familiarization with the insertion trajectory for this specific specimen but other contributing factors (e.g. EA softening) need to be further elucidated with several EAs. Future evaluations can help determine if this orientation change is influenced by surgeon expertise.

Robotic Cochlear Implant Surgery: Imaging-Based Evaluation of Feasibility in Clinical Routine

Background: Robotic surgery has been proposed in various surgical fields to reduce recovery time, scarring, and to improve patients' outcomes. Such innovations are ever-growing and have now reached the field of cochlear implantation. To implement robotic ear surgery in routine, it is of interest if preoperative planning of a safe trajectory to the middle ear is possible with clinically available image data.Methods: We evaluated the feasibility of robotic cochlear implant surgery in 50 patients (100 ears) scheduled for routine cochlear implant procedures based on clinically available imaging. The primary objective was to assess if available high-resolution computed tomography or cone beam tomography imaging is sufficient for planning a trajectory by an otological software. Secondary objectives were to assess the feasibility of cochlear implant surgery with a drill bit diameter of 1.8 mm, which is the currently used as a standard drill bit. Furthermore, it was evaluated if feasibility of robotic surgery could be increased when using smaller drill bit sizes. Cochlear and trajectory parameters of successfully planned ears were collected. Measurements were carried out by two observers and the interrater reliability was assessed using Cohen's Kappa.Results: Under the prerequisite of the available image data being sufficient for the planning of the procedure, up to two thirds of ears were eligible for robotic cochlear implant surgery with the standard drill bit size of 1.8 mm. The main reason for inability to plan the keyhole access was insufficient image resolution causing anatomical landmarks not being accurately identified. Although currently not applicable in robotic cochlear implantation, narrower drill bit sizes ranging from 1.0 to 1.7 mm in diameter could increase feasibility up to 100%. The interrater agreement between the two observers was good for this data set.Discussion: For robotic cochlear implant surgery, imaging with sufficient resolution is essential for preoperative assessment. A slice thickness of &lt;0.3 mm is necessary for trajectory planning. This can be achieved by using digital volume tomography while radiation exposure can be kept to a minimum. Furthermore, surgeons who use the software tool, should be trained on a regular basis in order to achieve planning consistency.