[Planning tools and indications for "virtual surgery" for the Bonebridge bone conduction system. German version]. / Planungstools und Indikationen zur "virtuellen Chirurgie" beim Knochenleitungssystem Bonebridge.

BACKGROUND: Implantation of the Bonebridge (MED-EL, Innsbruck, Austria), an active semi-implantable transcutaneous bone conduction hearing system, involves the risk of impression or a lesion in intracranial structures, such as the dura or sigmoid sinus. Therefore, determining the optimal implant position requires careful preoperative radiological planning. OBJECTIVE: The aim of this study was to provide an overview of the possibilities for preoperative radiological planning for the Bonebridge implantation and to evaluate their indications and feasibility. MATERIALS AND METHODS: A systematic literature search was conducted in the PubMed/MEDLINE database for all studies with preoperative planning or implant placement as the primary endpoint or that secondarily mention preoperative planning. RESULTS: Of 558 studies, 49 fulfilled the inclusion criteria. In 18 studies, preoperative planning and floating mass transducer (FMT) placement were the primary endpoints, whereas in 31 studies, preoperative planning was described secondarily. CONCLUSION: There are both freely available and commercial tools involving different time commitments for preoperative three-dimensional (3D) planning and intraoperative transfer. Preoperative 3D planning can increase the safety of Bonebridge implantation.

Planning tools and indications for "virtual surgery" for the Bonebridge bone conduction system.

BACKGROUND: Implantation of the Bonebridge (MED-EL, Innsbruck, Austria), an active semi-implantable transcutaneous bone conduction hearing system, involves the risk of impression or a lesion in intracranial structures, such as the dura or sigmoid sinus. Therefore, determining the optimal implant position requires careful preoperative radiological planning. OBJECTIVE: The aim of this study was to provide an overview of the possibilities for preoperative radiological planning for the Bonebridge implantation and to evaluate their indications and feasibility. MATERIALS AND METHODS: A systematic literature search was conducted in the PubMed/MEDLINE database for all studies with preoperative planning or implant placement as the primary endpoint or that secondarily mention preoperative planning. RESULTS: Of 558 studies, 49 fulfilled the inclusion criteria. In 18 studies, preoperative planning and floating mass transducer (FMT) placement were the primary endpoints, whereas in 31 studies, preoperative planning was described secondarily. CONCLUSION: There are both freely available and commercial tools involving different time commitments for preoperative three-dimensional (3D) planning and intraoperative transfer. Preoperative 3D planning can increase the safety of Bonebridge implantation.

Postural regulation and stability with acoustic input in normal-hearing subjects.

BACKGROUND: Postural regulation is based on complex interactions among postural subsystems. The auditory system too appears to have an influence on postural control. OBJECTIVE: The aim of this study was to measure the influence of auditory input on postural control and to gain a deeper understanding of the interactions between auditory input and postural subsystems including subjective aspects. MATERIALS AND METHODS: In 30 healthy normal-hearing subjects, postural regulation and stability was measured with the Interactive Balance System (IBS; Inc. neurodata GmbH, Wien, Österreich) in 8 test positions with noise (frontal presentation) and plugged without noise. The IBS is an electrophysiological measurement device that measures postural control at the product level (e.g., stability, weight distribution) and the mechanisms of postural subsystems at the process level based on frequency-oriented fast-Fourier analysis of force-time relation. RESULTS: At the process level, we found a relevant reduction (ηp2 ≥ 0.10) of postural regulation with noise in the frequency bands F1 (visual and nigrostriatal system ηp2 = 0.122) and F2-4 (peripheral vestibular system ηp2 = 0.125). At the product level, the weight distribution index (WDI) parameter showed a relevant increase with noise (ηp2 = 0.159). No difference between the auditory conditions was found for postural stability (parameter: stability indicator, ST). Substantial interindividual variations in the subjective estimation of the influence of auditory inputs on stability were observed. CONCLUSION: In this study, a shift in the activity of postural subsystems was observed with auditory input, while no difference was seen in ST. This leads to new insights into mechanisms of audiovestibular interaction.

[Postural regulation and stability with acoustic input in normal hearing subjects. German version]. / Posturale Regulation und Stabilität unter akustischem Input bei Normalhörenden.

BACKGROUND: Postural regulation is based on complex interactions among postural subsystems. The auditory system too appears to have an influence on postural control. OBJECTIVE: The aim of this study was to measure the influence of auditory input on postural control and to gain a deeper understanding of the interactions between auditory input and postural subsystems including subjective aspects. MATERIALS AND METHODS: In 30 healthy normal-hearing subjects, postural regulation and stability was measured with the Interactive Balance System (IBS; Inc. neurodata GmbH, Wien, Österreich) in 8 test positions with noise (frontal presentation) and plugged without noise. The IBS is an electrophysiological measurement device that measures postural control at the product level (e.g., stability, weight distribution) and the mechanisms of postural subsystems at the process level based on frequency-oriented fast-Fourier analysis of force-time relation. RESULTS: At the process level, we found a relevant reduction (ηp2 ≥ 0.10) of postural regulation with noise in the frequency bands F1 (visual and nigrostriatal system ηp2 = 0.122) and F2-4 (peripheral vestibular system ηp2 = 0.125). At the product level, the weight distribution index (WDI) parameter showed a relevant increase with noise (ηp2 = 0.159). No difference between the auditory conditions was found for postural stability (parameter: stability indicator, ST). Substantial interindividual variations in the subjective estimation of the influence of auditory inputs on stability were observed. CONCLUSION: In this study, a shift in the activity of postural subsystems was observed with auditory input, while no difference was seen in ST. This leads to new insights into mechanisms of audiovestibular interaction.

Influence of hearing on vestibulospinal control in healthy subjects.

BACKGROUND: Balance control is based on multisensory interaction. In addition to vestibular, proprioceptive and visual information, it seems that auditory input also plays an important role. OBJECTIVES: The aim of the study was to investigate the effect of hearing on vestibulospinal coordination and to obtain deeper knowledge about mechanisms of audiovestibular interaction. MATERIALS AND METHODS: In normal hearing, healthy subjects who performed the Unterberger (Fukuda) stepping test with and without frontal presentation of noise, the distance of displacement, the angle of displacement and the angle of rotation were measured by means of ultrasound based cranio-corpo-graphy (CCG). Additionally, subjective estimation of the effect of auditory input was compared to objective test results. RESULTS: In the noise condition, there was a significant improvement in the distance of displacement (mean with noise 66.9 cm± 33.5 standard deviation, SD, mean without noise 77.0 cm±32.7 SD, p< 0.001) and in the angle of rotation (mean with noise 14.2°± 10.1 SD, mean without noise 28.3°± 20.2 SD, p< 0.001), while no difference was found within the conditions regarding the angle of displacement (mean with noise 29.1°± 33.5 SD, mean without noise 30.0°± 34.0 SD, p= 0.641). Side-specific analysis revealed a positive correlation between angle of displacement and angle of rotation in the condition without noise (Spearman r = 0.441, p< 0.001). The rate of agreement between subjective estimation of noise influence and objective test results ranged between only 43% and 63%, depending on the question and endpoint. CONCLUSION: Hearing had a clearly beneficial effect of auditory inputs on vestibulospinal coordination, especially for distance of displacement and angle of rotation.

[Influence of hearing on vestibulospinal control in healthy subjects. German version]. / Einfluss des Hörens auf die vestibulospinale Kontrolle bei gesunden Probanden.

BACKGROUND: Balance control is based on multisensory interaction. In addition to vestibular, proprioceptive and visual information, it seems that auditory input also plays an important role. OBJECTIVES: The aim of the study was to investigate the effect of hearing on vestibulospinal coordination and to obtain deeper knowledge about mechanisms of audiovestibular interaction. MATERIALS AND METHODS: In normal hearing, healthy subjects who performed the Unterberger (Fukuda) stepping test with and without frontal presentation of noise, the distance of displacement, the angle of displacement and the angle of rotation were measured by means of ultrasound based cranio-corpo-graphy (CCG). Additionally, subjective estimation of the effect of auditory input was compared to objective test results. RESULTS: In the noise condition, there was a significant improvement in the distance of displacement (mean with noise 66.9 cm ± 33.5 standard deviation, SD, mean without noise 77.0 cm ± 32.7 SD, p < 0.001) and in the angle of rotation (mean with noise 14.2°â€¯± 10.1 SD, mean without noise 28.3°â€¯± 20.2 SD, p < 0.001), while no difference was found within the conditions regarding the angle of displacement (mean with noise 29.1°â€¯± 33.5 SD, mean without noise 30.0°â€¯± 34.0 SD, p = 0.641). Side-specific analysis revealed a positive correlation between angle of displacement and angle of rotation in the condition without noise (Spearman r = 0.441, p < 0.001). The rate of agreement between subjective estimation of noise influence and objective test results ranged between only 43% and 63%, depending on the question and endpoint. CONCLUSION: Hearing had a clearly beneficial effect of auditory inputs on vestibulospinal coordination, especially for distance of displacement and angle of rotation.