Automated detection of electrically evoked stapedius reflexes (eSR) during cochlear implantation.

INTRODUCTION: In cochlear implantation, objective fitting methods are needed to optimize audiological results in small children or patients with poor compliance. Intraoperatively measured electrically evoked stapedius reflexes (eSR) can be used as a marker for the patient's discomfort level. The aim of this study was to develop and evaluate an automated detection method for eSR and to compare it to the detection rate of the surgeon and independent observers. METHODS: Cochlear implantation using a fully digital surgical microscope was performed. Movements of the stapedius tendon were recorded and analyzed by means of computer vision technique. Differences in eSR elicited by stimulating electrodes at different cochlear locations (basal, middle and apical) were analyzed. The eSR detection rate of the image processing algorithm was compared to the surgeon's detection rate and to those of two less experienced observers. RESULTS: A total of 387 electrically impulses were applied. The stimulation of middle turn electrodes showed significantly higher detection rates (50.4%) compared to the basal (40.0%; p = 0.001) and apical (43.6%; p = 0.03) turn. The software identified significantly more of the applied stimuli (58.4%) compared to the surgeon (46.3%; p = 0.0007), the intermediate observer (37.7%; p < 0.0001) and the unexperienced observer (41.3%; p < 0.0001). CONCLUSION: The feasibility of an automated intraoperative software-based detection of eSR is demonstrated. By improving the eSR detection methods and their clinical applicability, their utility in objective cochlear implant fitting may be substantially increased.

Intraoperative quantification of floating mass transducer coupling quality in active middle ear implants: a multicenter study.

PURPOSE: Evaluating the effectiveness of intraoperative auditory brainstem responses (ABRs) to stimulation by the Vibrant Soundbridge (VSB) active middle ear implant for quantifying the implant's floating mass transducer (FMT) coupling quality. METHODS: In a diagnostic multicentric study, patients (> 18 years) who received a VSB with different coupling modalities were included. Pre- and postoperative bone conduction thresholds, intraoperative VSB-evoked ABR thresholds (VSB-ABR) using a modified audio processor programmed to preoperative bone conduction thresholds, postoperative vibrogram thresholds, and postoperative VSB-ABR thresholds were measured. Coupling quality was calculated from the difference between the pure tone average at 1000, 2000, and 4000 Hz (3PTA) vibrogram and postoperative 3PTA bone conduction thresholds. RESULTS: Twenty-three patients (13 males, 10 females, mean age 56.6 (± 12.5) years) were included in the study. Intraoperative VSB-ABR response thresholds could be obtained in all except one patient where the threshold was > 30 dB nHL. Postoperatively, an insufficient coupling of 36.7 dB was confirmed in this patient. In a Bland-Altman analysis of the intraoperative VSB-ABRs and coupling quality, the limits of agreement exceeded ± 10 dB, i.e., the maximum allowed difference considered as not clinically important but the variation was within the general precision of auditory brainstem responses to predict behavioral thresholds. Five outliers were identified. In two patients, the postoperative VSB-ABR thresholds were in agreement with the coupling quality, indicating a change of coupling before the postoperative testing. CONCLUSION: The response thresholds recorded in this set-up have the potential to predict the VSB coupling quality and optimize postoperative audiological results.

Would an endosteal CI-electrode make sense? Comparison of the auditory nerve excitability from different stimulation sites using ESRT measurements and mathematical models.

UNLABELLED: Regarding potential endosteal cochlear implant electrodes, the primary goal of this paper is to compare different intra- and extra-cochlear stimulation sites in terms of current strengths needed for stimulating the auditory nerve. Our study was performed during routine cochlear implantation using needle electrodes for electric stimulation and by visually recording electrically elicited stapedius reflexes (ESRT) as a measure for the stimulus transfer. Of course this rather simple setup only allows rough estimations, which, however, may provide further arguments whether or not to proceed with the concept of an endosteal electrode. In addition, a mathematical model is being developed. In a pilot study, intra-operative electric stimuli were applied via a needle electrode commonly used for the promontory stimulation test. Thus, stapedius reflex thresholds (ESRTs), electrically elicited via the needle from different points inside and outside the cochlea served as indicators for the suitability of different electrode positions towards the modiolus. Tests were performed on 11 CI-recipients. In addition, the extension of electrical fields from different stimulation sites is simulated in a mathematical cochlea model. In most patients ESRT measurements could be performed and evaluated. Thus an "endosteal" stimulation seems possible, although the current intensities must be higher than at intraluminal stimulation sites. Moreover, our model calculations confirm that the extension of electric fields is less favourable with increasing distance from the electrode to the ganglion nerve cells. In terms of hearing, the concept of an endosteal electrode should only be promoted, if its superiority for hearing preservation can be proven, e.g. in animal experiments. However, for other indications like the electric suppression of tinnitus, further research seems advisable. LEVELS OF EVIDENCE: N/A.

Monitoring residual hearing during cochlear implantation by intra-operative brainstem audiometry.

OBJECTIVE: Aim of this paper is to prove the applicability of intra-operative recordings of auditory brainstem responses during cochlear implantation. METHODS: The clinical practicability of intra-operative monitoring of hearing thresholds (Notched-Noise BERA, Amplitude Modulation Following Response [AMFR]) is presented in the respective case. The recordings were performed prior to the cochlear implantation and were compared with those obtained during and after cochlear implantation. RESULTS: It is demonstrated that the patient's cochlear function can be monitored; residual hearing is available after surgery. CONCLUSION: The possibility of monitoring of hearing thresholds may add some security to the concept of electric-acoustic stimulation.

"Physiological" Ear Clicking: Its Origin and Potential Usability as a Test Tool for the Eustachian Tube Function.

OBJECTIVE: To explore the origin of "physiological" ear clicks during deglutition or other pharyngeal movements, which, in contrast to disturbing frequent clicks under pathologic conditions, mostly remain unnoticed by the patient. STUDY DESIGN: Clinical experimental study at a tertiary referral center. METHODS: Ear clicks were recorded by a microphone sealing the external ear canal parallel to endoscopic or manometric evaluations of the Eustachian tube function. RESULTS: Obviously, the acoustic signals (clicks) appear when the tube opens. The clicks might be explained by a disruption of fluid or mucus films covering the mucosa. As in our tests clicks could be recorded regularly, they might potentially be used as indicators in a new tube function test, which has to be elaborated.

Electromyographical recording of the electrically elicited stapedius reflex via a bipolar hook electrode.

OBJECTIVE: To prove the feasibility of recording stapedius reflexes by bipolar electromyography intra-operatively during cochlea implant via a bipolar hook needle electrode. STUDY DESIGN: Prospective study. SETTING: Tertiary referral center. PATIENTS: Adults receiving a MED-EL cochlear implant. INTERVENTION: Diagnostic. MAIN OUTCOME MEASURES: Stapedius reflex responses can be recorded by electromyography. RESULTS: A double hook electrode could be inserted into the muscle tissue via the natural opening of the pyramid process along with the stapedius tendon. In 7 out of 10 patients supplied with MED-EL CIs (PULSARCI100 or SONATATI100), electrically elicited stapedius reflex potentials were recorded after eliminating stimulation artifacts caused by electromagnetic fields during electrical stimulation by low pass filtering. CONCLUSION: Intraoperative stapedius reflex recording by bipolar electromyography via a hook electrode is feasible. Further research will show whether these signals may be used for establishing a self-adjusting speech processor.

[Analysis of voice parameters after conservative treatment of laryngeal paralysis with conventional voice exercises or neuromuscular electrophonatory stimulation]. / Analyse von Stimmparametern nach konservativer Behandlung von Larynxparesen mit konventioneller Stimmübung oder neuromuskulärer elektrophonatorischer Stimulation.

Two groups of patients with unilateral or bilateral paresis of the nervus laryngeus inferior were treated with conventional voice therapy or neuromuscular electrophonatory stimulation (NMEPS). A few had additional paresis of the nervus laryngeus superior. After therapy pareses resolved or were compensated for. Successful therapy outcome can be verified on the basis of voice quality parameters. Significant improvements for both therapy groups were observed in case of parameters indicating frequency irregularities and noise-to-harmonic ratio. Only the patients treated with NMEPS reached significantly better results in case of soft phonation index after resolution of paresis.