Increasing the reliability of real-time electrocochleography during cochlear implantation: a standardized guideline.

PURPOSE: Electrocochleography (ECochG) measures electrical potentials generated by the inner ear in response to acoustic stimulation. Real-time (rt) recordings are increasingly used during cochlear implant (CI) surgeries to monitor the inner ear function. However, the performance of rt-ECochG is a delicate measurement procedure involving several pitfalls, which lead to inaccurate or invalid signal recordings in up to 20%. In order to use the technique routinely in CI candidates, an improvement in measurement reliability must be achieved. METHODS: In our prospective study, we systematically investigated potential pitfalls and error sources during rt-ECochG recordings. We performed experiments (i) on a head and torso simulator, (ii) on a whole-head cadaver specimen, (iii) as well as in vivo during rt-ECochG recordings in CI recipients. After analyzing experiments i-iii, a standardized measurement procedure was developed. We followed this guideline in 10 CI recipients to test the measurement reliability. RESULTS: Besides improper installation, surgical and patient-specific factors influenced the measured signal. In particular, the unattenuated presentation of the acoustic stimulus was of importance. We summarized our findings in a standardized guideline. Following this guideline, we measured successful intraoperative ECochG recordings in 9/10 patients. CONCLUSIONS: Our error analysis improved the understanding of successful rt-ECochG measurements. When following our proposed guideline, we achieved more reliable intraoperative ECochG recordings.

The accuracy of image-based safety analysis for robotic cochlear implantation.

PURPOSE: To evaluate the accuracy and reliability of image-based safety analysis for robotic cochlear implantation (RCI) in an ex vivo assessment. METHODS: The accuracy was evaluated in a study on 23 human temporal bones. For image analysis, a computer-assisted safety analysis based on intraoperative cone beam computed tomography was implemented. The method automatically segments the drill tunnel and predicts the distance between the tunnel and the facial nerve. In addition, the drilling error at the target is predicted. The predicted distances were compared with the actually drilled distances measured in postoperative high-resolution micro-computed tomography scans. The automatic method was compared to accuracies associated with a manual analysis of the image data. RESULTS: The presented computerized image-based analysis enabled the proximity of the facial nerve to the drill trajectory to be predicted with an accuracy of 0.22 ± 0.15 mm and drilling error at the target to be predicted with an accuracy of 0.11 mm ± 0.08 during N = 19 RCI procedures. The manual assessment of facial nerve proximity was performed with an accuracy of 0.34 ± 0.20 mm by a trained clinical expert. CONCLUSION: The assessment of intraoperative CT-based imaging presents multiple benefits over alternative safety mechanisms including early detection and applicability even in cases of malformation of the mastoid. This work presents a computer-assisted approach to image analysis that enables procedure safety measurements to be reliably performed with superior accuracy to other proposed safety methodologies, at a safe distance from the facial nerve. Its application must, however, be considered in relation to associated costs (time, cost, irradiation) and the dependence of the measure on a reliable preoperative segmentation.

Paediatric traffic accident and obstructive sleep apnoea by antrochoanal polyps: case report and literature review.

Antrochoanal polyps are hyperplasias of the nasal mucosa, which have their origin in the maxillary sinus and extend through the nasal cavity and the choanae into the naso- and oropharynx. In children antrochoanal polyps represent one of the more frequent manifestations of paediatric nasal polyposis. Most studies on antrochoanal polyps in children report only on nasal obstruction, hyponasal speech and snoring, which are also encountered in the most common cause of obstructive sleep apnoea syndrome; i.e. adenoid or tonsillar hyperplasia. Only very few studies report on additional health hazards by antrochoanal polyps ranging from obstructive sleep apnoea syndrome to swallowing disorders and cachexia. We present the case of an 8 year old girl with a bicycle accident caused by excessive daytime sleepiness and obstructive sleep apnoea syndrome due to an extensive antrochoanal polyp. After a transnasal polypectomy and meatotomy type II the obstructive sleep apnoea and day time sleepiness resolved completely. Awareness of this additional health hazard is important and correct evaluation and timely diagnosis of a potential antrochoanal polyp is mandatory because minimally invasive rhinosurgery is highly curative in preventing further impending problems.