Training Performance Assessment for Intracranial Aneurysm Clipping Surgery Using a Patient-Specific Mixed-Reality Simulator: A Learning Curve Study.

BACKGROUND AND OBJECTIVES: The value of simulation-based training in medicine and surgery has been widely demonstrated. This study investigates the introduction and use of a new mixed-reality neurosurgical simulator in aneurysm clipping surgery, focusing on the learning curve and performance improvement. METHODS: Five true-scale craniotomy head models replicating patient-specific neuroanatomy, along with a mixed-reality simulator, a neurosurgical microscope, and a set of microsurgical instruments and clips, were used in the operation theater to simulate aneurysm microsurgery. Six neurosurgical residents participated in five video-recorded simulation sessions over 4 months. Complementary learning modalities were implemented between sessions. Thereafter, three blinded analysts reported on residents' use of the microscope, quality of manipulation, aneurysm occlusion, clipping techniques, and aneurysm rupture. Data were also captured regarding training time and clipping attempts. RESULTS: Over the course of training, clipping time and number of clipping attempts decreased significantly (P = .018, P = .032) and the microscopic skills improved (P = .027). Quality of manipulation and aneurysm occlusion scoring improved initially although the trend was interrupted because the spacing between sessions increased. Significant differences in clipping time and attempts were observed between the most and least challenging patient models (P = .005, P = .0125). The least challenging models presented higher rates of occlusion based on indocyanine green angiography evaluation from the simulator. CONCLUSION: The intracranial aneurysm clipping learning curve can be improved by implementing a new mixed-reality simulator in dedicated training programs. The simulator and the models enable comprehensive training under the guidance of a mentor.

How much space is needed for decompressive surgery in malignant middle cerebral artery infarction: Enabling single-stage surgery.

Introduction: Decompressive hemicraniectomy (DCE) is routinely performed for intracranial pressure control after malignant middle cerebral artery (MCA) infarction. Decompressed patients are at risk of traumatic brain injury and the syndrome of the trephined until cranioplasty. Cranioplasty after DCE is itself associated with high complication rates. Single-stage surgical strategies may eliminate the need for follow-up surgery while allowing for safe brain expansion and protection from environmental factors. Research question: Assess the volume needed for safe expansion of the brain to enable single-stage surgery. Materials and methods: We performed a retrospective radiological and volumetric analysis of all patients that had DCE in our clinic between January 2009 and December 2018 and met inclusion criteria. We investigated prognostic parameters in perioperative imaging and assessed clinical outcome. Results: Of 86 patients with DCE, 44 fulfilled the inclusion criteria. Median brain swelling was 75.35 mL (8.7-151.2 mL). Median bone flap volume was 113.3 mL (73.34-146.1 mL). Median brain swelling was 1.62 mm below the previous outer rim of the skull (5.3 mm to -2.19 mm). In 79.6% of the patients, the volume of removed bone alone was equivalent to or larger than the additional intracranial volume needed for brain swelling. Discussion and conclusion: The space provided by removal of the bone alone was sufficient to match the expansion of the injured brain after malignant MCA infarction in the vast majority of our patientsA subgaleal space-expanding flap with a minimal offset can provide protection from trauma and atmospheric pressure without compromising brain expansion.

Probabilistic Subthalamic Nucleus Stimulation Sweet Spot Integration Into a Commercial Deep Brain Stimulation Programming Software Can Predict Effective Stimulation Parameters.

OBJECTIVES: Subthalamic nucleus (STN) deep brain stimulation (DBS) programming in patients with Parkinson disease (PD) may be challenging, especially when using segmented leads. In this study, we integrated a previously validated probabilistic STN sweet spot into a commercially available software to evaluate its predictive value for clinically effective DBS programming. MATERIALS AND METHODS: A total of 14 patients with PD undergoing bilateral STN DBS with segmented leads were included. A nonlinear co-registration of a previously defined probabilistic sweet spot onto the manually segmented STN was performed together with lead reconstruction and tractography of the corticospinal tract (CST) in each patient. Contacts were ranked (level and direction), and corresponding effect and side-effect thresholds were predicted based on the overlap of the volume of activated tissue (VTA) with the sweet spot and CST. Image-based findings were correlated with postoperative clinical testing results during monopolar contact review and chronic stimulation parameter settings used after 12 months. RESULTS: Image-based contact prediction showed high interrater reliability (Cohen kappa 0.851-0.91). Image-based and clinical ranking of the most efficient ring level and direction of stimulation were matched in 72% (95% CI 57.0-83.3) and 65% (95% CI 44.9-81.2), respectively, across the whole cohort. The mean difference between the predicted and clinically observed effect thresholds was 0.79 ± 0.69 mA (p = 0.72). The median difference between the predicted and clinically observed side-effect thresholds was -0.5 mA (p < 0.001, Wilcoxon paired signed rank test). CONCLUSIONS: Integration of a probabilistic STN functional sweet spot into a surgical programming software shows a promising capability to predict the best level and directional contact(s) as well as stimulation settings in DBS for PD and could be used to optimize programming with segmented lead technology. This integrated image-based programming approach still needs to be evaluated on a bigger data set and in a future prospective multicenter cohort.

Space-expanding flap in decompressive hemicraniectomy for stroke.

OBJECTIVE: Decompressive hemicraniectomy (DCE) is the standard of care for space-occupying malignant infarction of the medial cerebral artery in suitable patients. After DCE, the brain is susceptible to trauma and at risk for the syndrome of the trephined. This study aimed to assess the feasibility of using temporary space-expanding flaps, implanted during DCE, to shield the brain from these risks while permitting the injured brain to expand. METHODS: The authors performed a prospective feasibility study to analyze the safety of space-expanding flaps in 10 patients undergoing DCE and evaluated clinical and radiological outcomes. RESULTS: The relatives of 1 patient withdrew consent, leaving 9 patients in the final analysis. No patients required removal of the space-expanding flap because of uncontrolled increase of intracranial pressure or infection. One patient required additional external ventricular drainage and 1 received mannitol. The mean (range) midline shift decreased from 6.67 (3-12) mm to 1.26 (0-2.6) mm after DCE with the space-expanding flap. The authors observed no cases of sinking skin flap syndrome, other complications, or deaths. One patient underwent further treatment due to infection of the reimplanted autologous bone flap. Two patients later refused cranioplasty, preferring to keep the space-expanding flap and thus avoid the potential risks of cranioplasty. CONCLUSIONS: This feasibility study showed that the concurrent use of space-expanding flaps appeared to be safe in patients who underwent DCE for malignant infarction of the medial cerebral artery. Moreover, space-expanding flaps may permit patients to avoid a second surgery for reimplantation of the autologous bone flap and the risks inherent to this procedure.

Negligible Systemic Uptake of Suprafascial Vancomycin Powder Following Instrumented Posterior Spinal Fusion-Preliminary Results From A Randomized Clinical Trial (VANCO Trial).

BACKGROUND: Intrawound vancomycin powder is an emerging strategy to reduce surgical site infections (SSIs) in spine surgery. However, there are concerns relating to its safety profile and toxicity. Data on systemic uptake of suprafascially administered vancomycin powder following instrumented spinal fusion is lacking. OBJECTIVE: To study the systemic uptake and safety of suprafascially administered vancomycin powder in the early postoperative phase following open instrumented posterior spinal fusion. METHODS: This was a substudy of an ongoing randomized clinical trial. Eligible adult patients were randomized 1:1 to either receive suprafascial vancomycin powder before wound closure or not to receive vancomycin powder. Serum vancomycin levels were assessed on postoperative days 1 and 2, serum creatinine levels were measured pre- and post-operatively. Adverse events up to 6 wk following surgery were recorded. RESULTS: Among 34 randomized patients (mean age 62 yr, range 31-84 yr; 18 [53%] women), 17 received vancomycin powder. No detectable serum vancomycin levels (>4.0 mg/L) were found. Proportion of adverse events per patient in the vancomycin and control group, respectively, were 29.4% (5/17) vs 11.8% (2/17) (OR 3.12; 95% CI, 0.52; 19.38; P = .398). No patient had nephrotoxicity or ototoxicity in either group. CONCLUSION: Suprafascial vancomycin powder in open instrumented spinal fusion surgery is safe and results in negligible systemic uptake. Final results of the VANCO Trial need to be awaited for conclusive data on the efficacy of vancomycin for SSI prevention and its impact on wound healing.

Screening For Pulmonary Hypertension With Multidetector Computed Tomography Among Patients With Severe Aortic Stenosis Undergoing Transcatheter Aortic Valve Implantation.

Aim: To assess the accuracy of multi-detector computed tomography (MDCT) derived pulmonary vessel measurements in predicting pulmonary hypertension (PH) among patients with severe symptomatic aortic stenosis (AS) undergoing transcatheter aortic valve implantation (TAVI). Background: PH is common among patients with severe AS undergoing TAVI and is associated with adverse outcomes. MDCT is the imaging modality of choice to assess anatomical dimensions among patients selected for TAVI. Methods: One hundred and thirty-nine patients with severe AS undergoing TAVI with both CT scans and right heart catheterizations (RHC) were included. CT diameters of the main pulmonary artery (MPA), right (RPA) and left (LPA), and ascending aorta (AA) were measured. The relationship between CT measurements and PA pressures assessing using RHC was tested with linear regression. Results: The CT derived ratio of the diameter of the MPA to the diameter of the AA (PA/AAratio) correlated best with mean PA pressure (R2 = 0.48) and PA systolic pressure (R2 = 0.50). Receiver operating characteristic curve analysis showed that the PA/AAratio is a moderate predictor of PH (AUC 0.74, 95% CI 0.65-0.83, p < 0.0001) and that the optimal cut off point is 0.80 (sensitivity 56%, specificity 88%, positive predictive value 95.5%, negative predictive value 30.6% for PH). Conclusions: Elderly patients with severe AS and PA/AAratio values ≥ 0.80 on MDCT are more likely to have PH but PH cannot be reliably excluded among such patients with lower PA/AAratio values.