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.

Combined meropenem and linezolid as a systemic treatment for postoperative endophthalmitis.

PURPOSE: The aim of this study was to evaluate the antibiotic treatment of postoperative endophthalmitis with combined systemic meropenem and linezolid. METHODS: A retrospective analysis of endophthalmitis treated with systemic meropenem and linezolid compared to conventional systemic antibiotics by evaluation of outcome and adverse effects was carried out. RESULTS: 26 patients with unilateral postoperative endophthalmitis with a systemic combination regimen of meropenem (2 g TID, mean duration of treatment 5.5 days) and linezolid (600 mg BID, mean duration of treatment 8.9 days) (group 1, mean follow-up time 140 days) were included in this study and compared to 45 postoperative endophthalmitis patients treated with conventional systemic antibiotics (group 2; mean follow-up time 320 days). In group 1, 69.2 % of eyes additionally received intravitreal amikacin and vancomycin (vs. 24.4 % in group 2; p < 0.001), in 92.3 % pars plana vitrectomy was performed (vs. 68.9 % in group 2, p = 0.047). Mean best corrected visual acuity improved from a baseline of 1.76 logMar for group 1 and 1.83 logMar for group 2 to 0.91 logMar (p = 0.0001) and 0.90 logMar (p < 0.0001), respectively, at the end of the follow-up, revealing no significant differences between the two groups at any time point (p > 0.05). Ocular complications were observed in 34.6 % of eyes in group 1 (vs. 37.8 % in group 2; p > 0.05). Adverse drug effects occurred significantly more frequently in group 1 (26.9 % vs. 4.4 % p = 0.02). CONCLUSION: In spite of the reported better penetration through the blood-ocular barrier and the broader antibacterial spectrum of meropenem and linezolid, no benefit in outcome was found in the present study. In contrast, adverse effects and costs of the combination regimen were significantly higher.