Quality control after cochlear implant surgery by means of rotational tomography.

OBJECTIVE: To investigate the intracochlear electrode position in using rotational tomography in adult cochlear implant patients. STUDY DESIGN: Retrospective. SETTING: Tertiary referral center. PATIENTS: Eighteen adult patients being implanted either with a Nucleus straight electrode array or a Contour electrode with a total of 22 implanted ears. Preoperative computed tomography had been without evidence for obliteration, ossification, or malformation of the cochlea. INTERVENTION: Rotational tomography. MAIN OUTCOME MEASURES: The intracochlear electrode position was evaluated with regard to scala tympani, scala vestibuli, and a dislocation from one scala to the other. The intraoperative procedure was compared with the electrode position by analyzing the operating reports. RESULTS: Preliminary results indicate, respectively, that there is a higher incidence of intracochlear trauma in using the Contour electrode array than expected with a more frequent dislocation of electrode arrays from scala tympani to scala vestibuli and that there is a higher rate of scala vestibuli insertions. CONCLUSIONS: The impact of these findings may influence further developments of electrode arrays as well as surgical techniques for implantation.

Plasma vascular endothelial growth factor and serum soluble angiopoietin receptor sTIE-2 in patients with dural arteriovenous fistulas: a pilot study.

Our aim was to correlate concentrations of circulating vascular endothelial growth factor (VEGF) and serum soluble angiopoietin receptor (sTIE-2) before and after endovascular treatment with the grading in human dural arteriovenous fistulas (DAVFs). In ten patients with DAVFs undergoing diagnostic cerebral angiography and endovascular intervention, pre-treatment and post-treatment levels of plasma VEGF and serum TIE-2 were examined in a prospective study design. A total of 32 plasma samples and 19 serum samples was collected from the cubital vein, the arterial sheath before and--if applicable--after intervention. Plasma VEGF and serum Tie-2 levels were measured by standardized ELISA protocols. In eight of ten patients with DAVF increased circulating VEGF levels (elevation of more than mean + 2 SD of published normal values) were found, whereas two patients showed increased sTIE-2 levels. Six of the seven patients treated by endovascular embolization displayed a post-interventional decrease of VEGF values. The serum TIE-2 levels decreased slightly after intervention. Pre-treatment vVEGF levels varied significantly between patients with grades I and II/III fistulas according to the Cognards classification system. Our pilot study suggests that assessment of angiogenesis parameters in patients with DAVFs might correlate with the DAVFs' grade. To support the hypothesis that a change in angiogenic indicators may serve as indicators for a response to therapy, a larger number of patients should be followed for a longer time period.

Evaluation of the HiFocus electrode array with positioner in human temporal bones.

The aim of the study presented was to assess the insertion mode and possible intracochlear trauma after implantation of the HiFocus electrode with positioner in human temporal bones. The study was performed in five freshly frozen temporal bones. The position of electrodes was evaluated using conventional X-ray analysis, rotational tomography and histomorphological analysis. Insertion of the HiFocus electrode with positioner resulted in considerable trauma to fine cochlear structures including fracture of the osseous spiral lamina, dislocation of the electrode array from the scala tympani into the scala vestibuli and fracture of the modiolus close to the cochleostomy. The implication of the results regarding clinical outcome will be discussed.

Liquid 2-poly-hydroxyethyl-methacrylate embolization of experimental arteriovenous malformations: feasibility study.

BACKGROUND AND PURPOSE: We investigated the use of 2-poly-hydroxyethyl-methacrylate (2-P-HEMA) as an embolic agent in swine arteriovenous malformations (AVMs). METHODS: In seven mini swine, experimental AVMs were created surgically. The aim of treatment was complete embolization of the nidus compartment filled by the feeding artery, without brain embolization. Six animals received pure liquid 2-P-HEMA, and one, 50% 2-P-HEMA. For radiopacity, liquid 2-P-HEMA was mixed with tungsten powder. Six animals underwent angiographic follow-up within 5-8 mo (mean, 6.5 mo). Evaluation criteria were controllability, procedural reproducibility, and duration of the nidus occlusion. To detect complications, brain MR imaging and CT were performed. Histopathologic studies were performed to prove occlusion and assess histopathologic responses. RESULTS: 2-P-HEMA was easily injected through microcatheters, with a reproducible technique. Because of the radiopacity of the mixture, deep nidus penetration was controlled with fluoroscopy and confirmed with CT and histopathologic examination. In five AVMs embolized with pure 2-P-HEMA, feeder obliteration was long term. One animal had vasospasm during embolization, and complete obliteration of the main feeder was maintained for 3 mo, but partial recanalization developed 2 mo later. One animal receiving pure 2-P-HEMA had an infarction. In the animal embolized with 50% 2-P-HEMA, angiography and CT revealed embolic material in the circle of Willis; the animal died after embolization. No marked inflammatory reaction in the vessel wall or perivascular tissue was observed in the embolized AVMs. CONCLUSION: Experimental AVM embolization with pure 2-P-HEMA, made radiopaque with tungsten, is technically feasible in swine. Because of its properties, 2-P-HEMA has great potential as a therapeutic embolic agent.