Rüdiger Dahl

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 electical 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.

How reliable is visual assessment of the electrically elicited stapedius reflex threshold during cochlear implant surgery, compared with tympanometry?

OBJECTIVES To assess the reliability of visually assessed thresholds of the electrically elicited stapedius reflex, recorded during cochlear implant surgery, compared with intra-operative tympanometric threshold assessment. Intra-operatively recorded electrically elicited stapedius reflex thresholds vary considerably, and differ from those measured post-operatively by means of impedance changes (i.e. using tympanometry). Thus, any confounding effect of different intra-operative techniques and visual assessment inaccuracies should be excluded. METHODS Both techniques (i.e. visual observation and tympanometry) were performed intra-operatively in six patients, and threshold values were compared. RESULTS Recorded electrically elicited stapedius reflex thresholds were very similar for both techniques. Visually assessed thresholds were slightly higher in some cases and lower in others, compared with tympanometric thresholds. DISCUSSION There was almost no difference between reflex thresholds measured with the two different techniques under the same intra-operative conditions. Therefore, we conclude that differences between intra- and post-operative thresholds are not due to the use of different measuring techniques. The main reason for such differences is probably the influence of intra-operative narcotics on reflex thresholds.

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.

Beziehung zwischen Messung der stimmlichen Durchdringungsfähigkeit, Stimmstatus nach Pahn und ausgewählten Parametern des Stimmanalyseprogramms MDVP (Kay)

Es wird ein Messverfahren der stimmlichen Durchdringungsfähigkeit im Störlärm vorgestellt. Der Lärm besteht aus einer Frequenzmischung von Vokalen mit stimmhaften und stimmlosen Konsonanten. Gemessen wird die Verständlichkeit der Testmatrix als Ausdruck der stimmlichen Durchdringungsfähigkeit von sprachverdeckendem Störlärm. Die Ergebnisse mit mehr als 1000 Patienten zeigen signifikante Korrelationen zur Einschwingphase des Stimmstatus und zu den subjektiven Angaben des Patienten betreffend das Lautstärkesteigerungsvermögen, die stimmliche Belastungsdauer und das stimmliche Wohlbefinden. Das Verfahren eignet sich damit zur Stimmdiagnostik, zur Therapieverlaufskontrolle, zur Begutachtung und zur Eignungsuntersuchung für stimm-sprachliche Professionen.

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

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

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.