Optimizing Location of Subdermal Recording Electrodes for Intraoperative Facial Nerve Monitoring.

OBJECTIVE: The purpose of this study is to determine if different facial muscle groups demonstrate different responses to facial nerve stimulation, the results of which could potentially improve intraoperative facial nerve monitoring (IOFNM). METHODS: IOFNM data were prospectively collected from patients undergoing cochlear implantation. At different stages of nerve exposure, three sites were stimulated using a monopolar pulse. Peak electromyography (EMG) amplitude (µV) in four muscle groups innervated by four different branches of the facial nerve (frontalis-temporal, inferior orbicularis oculi-zygomatic, superior oribularis oris-buccal, and mentalis-marginal mandibular) were recorded. RESULTS: A total of 279 peak EMG amplitudes were recorded in 93 patients. At all three stimulating sites, the zygomatic branch mean peak EMG amplitudes were statistically greater than those of the temporal, buccal, and marginal mandibular branches (P < .05). At stimulating Site C, the marginal mandibular branch mean peak EMG was stronger than the temporal or buccal branches (P < .05). Of the 279 stimulations, the zygomatic branch demonstrated the highest amplitude in 128 (45.9%) trials, followed by the marginal mandibular branch (22.2%). CONCLUSIONS: When utilized, IOFNM should be performed with at least two electrodes, one of which is placed in the orbicularis oculi muscles and the other in the mentalis muscle. However, there is wide variability between patients. As such, in cases of suspected variant nerve anatomy or increased risk of injury (intradural procedures), surgeons should consider using more than two recording electrodes, with at least one in the orbicularis oculi muscle. LEVEL OF EVIDENCE: 3 Laryngoscope, 131:E2329-E2334, 2021.

Topical Triamcinolone on "Sweet Spots" to Block Dynamic Pain after Tonsillectomy and Uvulo-Palato-Pharyngo-Plasty.

OBJECTIVES: Severe pain on swallowing (or dynamic pain) has long been a problem in patients receiving tonsillectomy and uvulopalatopharyngoplasty for the treatment of obstructive sleep apnea syndrome and/or snoring. We have previously verified that dynamic pain after laser-assisted uvulopalatoplasty could immediately be mitigated by local treatments with topical triamcinolone on the "sweet spots" of the wounds. This study aimed to assess the efficacy of applying triamcinolone on "sweet spot" in surgical incisions instead of whole surgical wounds to alleviate dynamic pain of some oropharyngeal surgeries such as tonsillectomy and uvulopalatopharyngoplasty. METHODS: This study is a retrospective case series based on chart review of the participants. Forty-five subjects (31 males; 12~68 years, mean 34 years) with obstructive sleep apnea syndrome and/or snoring treated with tonsillectomy or uvulopalatopharyngoplasty were studied. Local treatments were done to sweet spots with triamcinolone on the 1st, 2nd, 3rd, and 7th days after the surgery. Evaluation of dynamic pain relief was performed by using a visual analogous scale. RESULTS: Sweet spots treatment led to instantaneous reduction of dynamic pain. The average improvement level was ≥72% (P ≤ .002). No gender effect was noted. CONCLUSION: Dynamic pain after tonsillectomy and uvulopalatopharyngoplasty could immediately be mitigated by local treatments upon sweet spots. Local treatments upon sweet spots were highly suggested to begin early post-operatively and be included in the take-home routines for patients receiving tonsillectomy and uvulopalatopharyngoplasty.

Rounded Insertion Technique for Cochlear Implantation Surgery to Treat Cystic Inner Ear Malformation.

OBJECTIVE: This article outlines the advantages and applicability of the rounded insertion technique of cochlear implants in patients with cystic inner ear malformation. This technique enables the insertion of the maximum number of electrodes and prevents the unwanted entry of electrodes into the internal auditory canal. METHODS: We conducted a retrospective chart review of consecutive patients with cochlear hypoplasia (CH) and/or common cavity (CC) who underwent CI (cochlear implantation) via rounded insertion technique. The position of the electrode array in each patient was confirmed postoperatively via X-ray, and the number of functional electrodes was confirmed during the mapping process. RESULTS: This study included five male and two female patients (median age: 3 years; age range: 2-7 years). Among the seven patients, four received a cochlear implant on the right side, one on the left side, and two bilaterally. Of the nine ears, six were cases of CH, and three were CC. All cochlear implant surgeries via rounded insertion technique were completed without complications. The maximum number of electrode contacts with fair function in the cystic cochlea was confirmed via postoperative X-ray and the subsequent mapping process. CONCLUSION: This consecutive series of patients demonstrated the safety and reliability of rounded insertion technique for CI in patients with CH and/or CC. LEVEL OF EVIDENCE: 4 Laryngoscope, 130:2229-2233, 2020.

Differences in the impedance of cochlear implant devices within 24 hours of their implantation.

Cochlear implantation is a surgical procedure, which is performed on severely hearing-impaired patients. Impedance field telemetry is commonly used to determine the integrity of the cochlear implant device during and after surgery. At the Department of Otolaryngology, Cheng Hsin General Hospital (Taipei, Taiwan), the cochlear implant devices are switched on within 24 hours of their implantation. In the present study, the impedance changes of Advanced Bionics™ cochlear implant devices were compared with previous studies and other devices. The aim was to confirm previous hypotheses and to explore other potential associated factors that could influence impedance following cochlear implantation. The current study included 12 patients who underwent cochlear implantation at Cheng Hsin General Hospital with Advanced Bionics cochlear implant devices. The cochlear devices were all switched on within 24 hours of their implantation. The impedance was measured and compared across all contact channels of the electrode, both intra-operatively and post-operatively. The intra-operative impedance was compared with the switch-on impedance (within 24 hours of the cochlear implantation); the impedance was notably increased for all contact channels at switch-on. Of the 16 channels examined, 4 channels had a significant increase in impedance between the intra-operative measurement and the switch-on measurement. To the best of our knowledge, the impedance of a cochlear implant device can be affected by the diameter of the electrode, the position of the electrode arrays in the scala tympani, sheath formation and fibrosis surrounding the electrode after implantation and electrical stimulation during or after surgery. When the results of the current study were compared with previous studies, it was found that the impedance changes were opposite to that of Cochlear™ implant devices. This may be explained by the position of the electrode arrays, sheath formation, the blow-out effect and differences in electrical stimulation.

Correction: Evolution of impedance field telemetry after one day of activation in cochlear implant recipients.

[This corrects the article DOI: 10.1371/journal.pone.0173367.].

Evolution of impedance field telemetry after one day of activation in cochlear implant recipients.

OBJECTIVES: Changes in impedance between 24 hours and one month after cochlear implantation have never been explored due to the inability to switch on within one day. This study examined the effect of early activation (within 24 hours) on the evolution of electrode impedance with the aim of providing information on the tissue-to-electrode interface when electrical stimulation was commenced one day post implantation. METHODS: We performed a retrospective review at a single institution. Patients who received a Nucleus 24RECA implant system (Cochlear, Sydney, Australia) and underwent initial switch-on within 24 hours postoperatively were included. Impedance measurements were obtained intraoperatively and postoperatively at 1 day, 1 week, 4 weeks, and 8 weeks. RESULTS: A significant drop in impedance was noted 1 day after an initial activation within 24 hours followed by a significant rise in impedance in all channels until 1 week, after which the impedance behaved differently in different segments. Basal and mid-portion electrodes revealed a slight increase while apical electrodes showed a slight decrease in impedance from 1 week to 8 weeks postoperatively. Impedance was relatively stable 4 weeks after surgery. CONCLUSIONS: This is the first study to report the evolution of impedance in all channels between initial mapping 1 day and 1 month after cochlear implantation. The underlying mechanism for the differences in behavior between different segments of the electrode may be associated with the combined effect of dynamics among the interplay of cell cover formation, electrical stimulation, and fibrotic reaction.

Safety and feasibility of initial frequency mapping within 24 hours after cochlear implantation.

CONCLUSION: Switch-on within 24 h after cochlear implantation can be safely and practically performed. The minimally invasive approach presented here also brought about benefits such as nonstop rehabilitation programs and shorter duration of uncertainty/worry for patients and their families about surgical outcomes. Those were important factors for international patients. Our research invites further studies to show whether instant commencement of electrical stimulation helps to expedite long-term hearing/speech performance in cochlear implantees. OBJECTIVES: Initial switch-on generally could not launch until weeks after cochlear implantation due to factors associated with wound conditions. Commencement of electrical stimulation within 24 h after the surgery has long been performed in our department on a routine basis. The idea issued from the need to sew-and-go for international patients. This study presents the safety and feasibility of the procedure. METHODS: Charts of 79 subjects with profound hearing impairment were studied. A minimally invasive approach was used for cochlear implantation, with an intention to control wound condition and tissue swelling. Hearing threshold was measured preoperatively and postoperatively. RESULTS: Initial switch-on within 24 h was done in all patients. Good hearing gain was obtained. No major complication occurred. There was no significant difference in hearing postoperatively that was attributable to the early switch-on.

Contribution of nonimplanted ear to pitch perception for prelingually deafened cochlear implant recipients.

INTRODUCTION: Bimodal stimulation (BMS) has been shown to be beneficial for the performance of pitch ranking in postlingually deafened adults. However, the contribution of nonimplanted ears to pitch perception with respect to duration of hearing aid (HAs) use for prelingually cochlear implantees remained unclear. This study aimed to investigate whether experiences/duration of HAs use in the nonimplanted ear improved pitch perception ability in this population of subjects. MATERIALS AND METHODS: Twenty-nine children with congenital/prelingual deafness of profound degree were studied. Test stimuli consisted of 2 sequential piano tones, ranging from C (256 Hz) to B (495 Hz). Children were asked to identify the pitch relationship between the 2 tones (i.e., same, higher, or lower). RESULTS: Duration of HAs use was the major factor related to the correct rate for pitch perception. Overall correct rate for pitch perception (O) could be best predicted by duration of HAs use (DuA) (O = 0.561XDuA, r = 0. 315, p = 0.002). DISCUSSION: Experiences of HAs use appear to improve pitch perception ability in prelingually cochlear implantees. This suggests that incorporation of HAs use early in life and through the postoperative rehabilitation program for prelingually deafened children with cochlear implants would be beneficial, although an association does not guarantee causality. A longitudinal study is needed to show whether improvement of music performance with duration of HAs use in these children is measurable using auditory evoked potentials.

Impedance and electrically evoked compound action potential (ECAP) drop within 24 hours after cochlear implantation.

Previous animal study revealed that post-implantation electrical detection levels significantly declined within days. The impact of cochlear implant (CI) insertion on human auditory pathway in terms of impedance and electrically evoked compound action potential (ECAP) variation within hours after surgery remains unclear, since at this time frequency mapping can only commence weeks after implantation due to factors associated with wound conditions. The study presented our experiences with regards to initial switch-on within 24 hours, and thus the findings about the milieus inside cochlea within the first few hours after cochlear implantation in terms of impedance/ECAP fluctuations. The charts of fifty-four subjects with profound hearing impairment were studied. A minimal invasive approach was used for cochlear implantation, characterized by a small skin incision (≈ 2.5 cm) and soft techniques for cochleostomy. Impedance/ECAP was measured intro-operatively and within 24 hours post-operatively. Initial mapping within 24 hours post-operatively was performed in all patients without major complications. Impedance/ECAP became significantly lower measured within 24 hours post-operatively as compared with intra-operatively (p<0.001). There were no differences between pre-operative and post-operative threshold for air-conduction hearing. A significant drop of impedance/ECAP in one day after cochlear implantation was revealed for the first time in human beings. Mechanisms could be related to the restoration of neuronal sensitivity to the electrical stimulation, and/or the interaction between the matrix enveloping the electrodes and the electrical stimulation of the initial switch-on. Less wound pain/swelling and soft techniques both contributed to the success of immediate initial mapping, which implied a stable micro-environment inside the cochlea despite electrodes insertion. Our research invites further studies to correlate initial impedance/ECAP changes with long-term hearing/speech performance.

Low body mass index and jaw movement are protective of hearing in users of personal listening devices.

OBJECTIVES/HYPOTHESIS: Sound pressure level delivered through personal listening devices (PLDs) and reaching the ear drum might be affected by body size and jaw movements. This study aimed to investigate whether jaw movement and/or smaller body mass index (BMI) resulted in decrease of sound pressure level within the ear canals of PLD users via an earbud earphone. STUDY DESIGN: Case series. METHODS: Forty-five normal-hearing subjects (16 males; mean age, 23.3 years) participated in this study. A probe-microphone system was used to measure sound pressure level in the external ear canal with music delivered from a media player via an earbud earphone. Test materials consisted of two 20-second excerpts from a heavy metal music piece. Subjects were instructed to adjust the volume of the media player to conform to three conditions for sound pressure measurement: comfortable, loud, and maximum. Measurements were then repeated while subjects mimicked chewing action under the same listening conditions. RESULTS: Sound pressure levels were significantly lower when measured with jaw movement than without jaw movement (P < .05). Sound pressure levels monitored with/without jaw movement were generally lower in subjects with a BMI<23 than those with a BMI ≥ 23 (P < .05). CONCLUSIONS: Jaw movement and low BMI (<23) reduced the overall sound level of PLDs at the ear canal. Sound pressure levels detected in the external ear canal of our subjects using earbud earphones were significantly lower under conditions of jaw movement/BMI <23. Our research invites further studies on a larger group of PLD users to correlate these variables with hearing threshold shifts over time.

Music training improves pitch perception in prelingually deafened children with cochlear implants.

OBJECTIVE: The comparatively poor music appreciation in patients with cochlear implants might be ascribed to an inadequate exposure to music; however, the effect of training on music perception in prelingually deafened children with cochlear implants remains unknown. This study aimed to investigate whether previous musical education improves pitch perception ability in these children. METHODS: Twenty-seven children with congenital/prelingual deafness of profound degree were studied. Test stimuli consisted of 2 sequential piano tones, ranging from C (256 Hz) to B (495 Hz). Children were asked to identify the pitch relationship between the 2 tones (same, higher, or lower). Effects of musical training duration, pitch-interval size, current age, age of implantation, gender, and type of cochlear implant on accuracy of pitch perception were evaluated. RESULTS: The duration of musical training positively correlated with the correct rate of pitch perception. Pitch perception performance was better in children who had a cochlear implant and were older than 6 years than in those who were aged < or =6 years (ie, preschool). Effect of pitch-interval size was insignificant on pitch perception, and there was no correlation between pitch perception and the age of implantation, gender, or type of cochlear implant. CONCLUSIONS: Musical training seems to improve pitch perception ability in prelingually deafened children with a cochlear implant. Auditory plasticity might play an important role in such enhancement. This suggests that incorporation of a structured training program on music perception early in life and as part of the postoperative rehabilitation program for prelingually deafened children with cochlear implants would be beneficial. A longitudinal study is needed to show whether improvement of music performance in these children is measurable by use of auditory evoked potentials.