Intra-Operative Neural Response Telemetry and Acoustic Reflex Assessment using an Advance-In-Stylet Technique and Modiolus-Hugging : A prospective cohort study

Objectives: The development of cochlear implant (CI) electrode arrays has focused on the use of a minimally invasive technique involving a modiolus-hugging placement of the electrode. The aim of this study was to evaluate the “advance-in-stylet” (AIS) technique compared to the advance-off-stylet (AOS) technique recommended for the current cochlear Nucleus® device. In the AIS technique, the stylet is not removed. We evaluated the electrical auditory thresholds measured when the stylet was removed (modiolus-hugging) compared to measurements taken with the stylet in place (lateral wall cochlea electrode placement). Methods: In this prospective cohort study, 30 consecutive patients received unilateral Nucleus Freedom® CIs using AIS insertion. Measurement of the acoustic reflex (AR) and neural response telemetry (NRT) were performed with the stylet in place (lateral wall placement of the electrodes) and then removed (perimodiolar placement), and the results compared. The responses were measured in the basal, middle and apical turns in both groups—with and without stylet. Results: The AIS surgery was completed without complication in 30 patients (16 males and 14 females, age range 3-54 years [mean 11]). Based on neural response telemetry, only apical electrodes showed statistically significant differences in thresholds, but the AR was not significantly different before or after stylet removal in any of the electrode groups tested. Conclusions: The effects of modiolus-hugging do not seem to result in a large difference in electrical stimulation thresholds so, in difficult cases, the stylet may be left in place without significantly changing the thresholds, except perhaps at the apical turn.

Anatomy-Based Programming

The ultimate goal of a cochlear implant device is to mimic the hearing through normal cochlea. A better understanding of normal cochlear function can help reaching this goal. The normal cochlea has a tonotopic mapping of the frequency representation in which each area on the cochlea is the most sensitive to a specific frequency. The array of the cochlear implant device has a number of electrodes each presenting a different frequency to the nearest area of the cochlea to where they are located. An anatomy-based programming strategy aims to present the frequency by the electrode contacts to which the cochlea is most sensitive to, according to the location of that electrode contact inside the cochlea. This chapter explores the details of the current understanding of the anatomy-based programming

An unusual location of retroperitoneal epidermoid cyst in a child: case report and a review of the literature

We report the case of a 4-year-old girl presenting with the retroperitoneal epidermoid cyst. The lesion presented as an intra-abdominal cyst on physical examination and was followed up with more specific investigations by ultrasound and computed tomographic scanning. The final diagnosis was obtained only after laparotomy where the cystic mass was completely excised and pathological examination was done. The patient is well at 3-year follow-up. epidermoid cyst of the reteroperitoneal space, although rare, should be considered in the differential diagnosis of incidentally discovered intra-abdominal cysts during investigation of irrelevant illnesses or during routine abdominal ultrasound scan

Suitable Electrode Choice for Robotic-Assisted Cochlear Implant Surgery: A Systematic Literature Review of Manual Electrode Insertion Adverse Events

BACKGROUND AND OBJECTIVE: The cochlear implant (CI) electrode insertion process is a key step in CI surgery. One of the aims of advances in robotic-assisted CI surgery (RACIS) is to realize better cochlear structure preservation and to precisely control insertion. The aim of this literature review is to gain insight into electrode selection for RACIS by acquiring a thorough knowledge of electrode insertion and related complications from classic CI surgery involving a manual electrode insertion process. METHODS: A systematic electronic search of the literature was carried out using PubMed, Scopus, Cochrane, and Web of Science to find relevant literature on electrode tip fold over (ETFO), electrode scalar deviation (ESD), and electrode migration (EM) from both pre-shaped and straight electrode types. RESULTS: A total of 82 studies that include 8,603 ears implanted with a CI, i.e., pre-shaped (4,869) and straight electrodes (3,734), were evaluated. The rate of ETFO (25 studies, 2,335 ears), ESD (39 studies, 3,073 ears), and EM (18 studies, 3,195 ears) was determined. An incidence rate (±95% CI) of 5.38% (4.4–6.6%) of ETFO, 28.6% (26.6–30.6%) of ESD, and 0.53% (0.2–1.1%) of EM is associated with pre-shaped electrodes, whereas with straight electrodes it was 0.51% (0.1–1.3%), 11% (9.2–13.0%), and 3.2% (2.5–3.95%), respectively. The differences between the pre-shaped and straight electrode types are highly significant (p < 0.001). Laboratory experiments show evidence that robotic insertions of electrodes are less traumatic than manual insertions. The influence of round window (RW) vs. cochleostomy (Coch) was not assessed. CONCLUSION: Considering the current electrode designs available and the reported incidence of insertion complications, the use of straight electrodes in RACIS and conventional CI surgery (and manual insertion) appears to be less traumatic to intracochlear structures compared with pre-shaped electrodes. However, EM of straight electrodes should be anticipated. RACIS has the potential to reduce these complications

Hearing Improvement after Partial Labyrinthectomy: Resection of petrous apex cholesterol granuloma

We present the case of a 57 year-old male presenting with symptomatic petrous apex cholesterol granuloma, multiple cranial nerve weaknesses and deafness of the left ear. The chosen intervention was a cholesterol granuloma resection via the translabyrinthine approach. This resulted in cranial nerve recovery and improved facial functionality. Hearing in the operated ear improved within 3 months after surgery. The patient experienced no postoperative complications. We conclude that a translabyrinthine approach can be used for drainage of petrous apex cholesterol granulomas with a chance of hearing loss recover

Application of anatomy-based spacing of electrode contacts for achieving a uniform semitonal resolution: A novel concept in cochlear implant electrode design

Abstract Using anatomy-based fitting, we can determine the place-specific map with individualized center frequencies for each electrode contact that is a closer match to the natural pitch-place of the cochlea. The primary objective of this study is to evaluate the tonal presentation across the electrode array and to calculate the semitone difference between each adjacent pair of contacts according to their anatomy-based map. The secondary objective is to determine the distancing of the contacts that would result in an equal semitone difference with a uniform tonal presentation. A total of 167 ears were included in this retrospective study. The frequencies across the electrode arrays were found to be unequally presented. The semitonal condensations were higher in the apical inter-contact spaces compared to the basal inter-contact spaces, being 3.0–2.3 semitones/mm (Kruskal Wallis test, p < 0.000). The anatomy-based spacing of the electrode contacts was larger in the basal inter-contact spaces compared to the apical inter-contact spaces, ranging from 1.92 to 1.48 mm. In conclusion, the current electrode designs do not have uniform tonal representation throughout the electrode array. There is a more condensed tonal presentation in the apical electrodes than in the basal electrodes, resulting in a lower tonal resolution in the apical region