Development and initial evaluation of a novel simulation model for comprehensive brain tumor surgery training.

BACKGROUND: Increasing technico-manual complexity of procedures and time constraints necessitates effective neurosurgical training. For this purpose, both screen- and model-based simulations are under investigation. Approaches including 3D printed brains, gelatin composite models, and virtual environments have already been published. However, quality of brain surgery simulation is limited due to discrepancies in visual and haptic experience. Similarly, virtual training scenarios are still lacking sufficient real-world resemblance. In this study, we introduce a novel simulator for realistic neurosurgical training that combines real brain tissue with 3D printing and augmented reality. METHODS: Based on a human CT scan, a skull base and skullcap were 3D printed and equipped with an artificial dura mater. The cerebral hemispheres of a calf's brain were placed in the convexity of the skullcap and tumor masses composed of aspic, water, and fluorescein were injected in the brain. The skullcap and skull base were placed on each other, glued together, and filled up with an aspic water solution for brain fixation. Then, four surgical scenarios were performed in the operating room as follows: (1) simple tumor resection, (2) complex tumor resection, (3) navigated biopsy via burr hole trepanation, and (4) retrosigmoidal craniotomy. Neuronavigation, augmented reality, fluorescence, and ocular-as well as screen-based (exoscopic)-surgery were available for the simulator training. A total of 29 participants performed at least one training scenario of the simulator and completed a 5-item Likert-like questionnaire as well as qualitative interviews. The questionnaire assessed the realism of the tumor model, skull, and brain tissue as well as the capability for training purposes. RESULTS: Visual and sensory realism of the skull and brain tissue were rated,"very good," while the sensory and visual realism of the tumor model were rated "good." Both overall satisfaction with the model and eligibility of the microscope and neurosurgical instruments for training purposes were rated with "very good." However, small size of the calf's brain, its limited shelf life, and the inability to simulate bleedings due to the lack of perfusion were significant drawbacks. CONCLUSION: The combination of 3D printing and real brain tissue provided surgical scenarios with very good real-life resemblance. This novel neurosurgical model features a versatile setup for surgical skill training and allows for efficient training of technological support like image and fluorescence guidance, exoscopic surgery, and robotic technology.

Dexamethasone phosphate in antibiotic ear drops for the treatment of acute bacterial otitis externa.

OBJECTIVES: To compare the efficacy and safety of polymyxin sulfate 7500 IU/neomycin sulfate 3500 IU/dexamethasone phosphate 0.1% (PN+Dx) otic solution with polymyxin sulfate 7500 IU/neomycin sulfate 3500 IU (PN-Dx) in patients with acute bacterial otitis externa (AOE), in order to determine the possible benefit of the addition of dexamethasone. RESEARCH DESIGN AND METHODS: Active controlled, double-blind, randomized, parallel group, multi-center clinical trial in ear, nose, and throat (ENT) specialist practices with a planned interim analysis for sample size adaptation. In total, 338 patients aged 18-76 who had a previous episode of otitis externa within the last year were randomized to receive 10 +/- 2 days of treatment with two drops, three times daily, of either PN+Dx or PN-Dx. MAIN OUTCOME MEASURES: Change in the clinical symptom score (consisting of the subscores redness, swelling, pain, and secretion) and of the visual analogue scale (VAS) rating for pain from Visit 1 (Day 1) to Visit 2 (Day 4 +/- 1), patient's assessment of efficacy at Visit 3 (Day 10 +/- 2), and the frequency and type of adverse events. RESULTS: There was a significantly greater reduction of swelling from Visit 1 to Visit 2 with PN+Dx, and more patients rated the efficacy of PN+Dx as 'very good' or 'good' at Visit 3 (p = 0.03). There was also a significantly greater decrease in the clinical symptom score from Visit 1 to Visit 2 in the PN+Dx group in patients who had at least a moderately severe symptom score with more than seven points at Visit 1 (p = 0.01) and in patients suffering from their current episode of otitis externa for more than 2 days (p = 0.02). In total, 14 adverse events were reported during the study period with no related adverse drug reactions for PN+Dx. CONCLUSIONS: The addition of dexamethasone phosphate to polymyxin B/neomycin significantly reduces swelling in patients with AOE and leads to significantly higher patient's ratings of treatment efficacy. It especially leads to an overall reduction of symptoms in cases of moderately or more severe otitis externa and cases lasting for more than 2 days.