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Background Hemorrhage rates of conservatively managed brainstem cavernous malformations (BSCMs) vary widely in the literature. We aimed to elucidate the reason for the variation and to add the results of our experience of BSCMs management over the past decade. Methods We performed a review of consecutive patients with BSCMs referred to our department in the period 2006–2018. A hemorrhagic event was defined as a radiographically verified intralesional and extralesional hemorrhage. Both retrospective and prospective hemorrhage rates were calculated based on the patient age in years, counted either from birth or from the time of initial presentation until the last contact (or until surgical resection). In addition, we retrieved and reviewed publications with a clear definition of hemorrhagic event and a detailed description of BSCM hemorrhage rate. Results In total, 118 patients with BSCMs were reviewed, and 78 patients (mean age on admission 45.9 years) were included in the final analysis. The retrospective and prospective hemorrhage rates were 1.9% (95% confidence interval 1.6%–2.3%) per year and 11.9% (95% confidence interval 7.5%–17.8%), respectively. The retrospective hemorrhage rate in the literature review ranged from 1.9% to 6.8% per year with a median value of 3.8%, whereas the prospective hemorrhage rate ranged between 4.1% and 21.5%, with a median value of 10.2%. Conclusions The reported hemorrhage rates are calculated in 2 different ways. In our patient cohort, both the retrospective and prospective hemorrhage rates were in accordance with those in the literature. The long-term hemorrhage rate lies between the prospective and retrospective rate.

Background Arteries that anastomose with the posterior inferior cerebellar artery (PICA) can harbor aneurysms. Case Description We present a case of a patient who suffered a subarachnoid hemorrhage as a result from an aneurysm on the left lateral spinal artery (LSA) that anastomosed to the PICA. The aneurysm was treated surgically, and the flow between the LSA and PICA was disrupted. The activated anastomotic network created a new anastomosis between the LSA and PICA, which was seen at 6 months' follow-up. Conclusions Careful follow-up is warranted in patients who have an activated anastomotic network because they can potentially develop aneurysms on newly created anastomoses.

Background and Objective High-field intraoperative magnetic resonance imaging (ioMRI) is becoming increasingly available in neurosurgery centers, where it has to be combined with intraoperative neurophysiologic monitoring (IONM). IONM needle electrodes remain on the patient during ioMRI and may cause image distortions and burns. We tested magnetic resonance (MR) -heating experimentally and investigated the prevalence of complications. Methods We studied electrodes that are certified for IONM, but not “MR conditional.” They consist of copper cables (length, 1.5 m) and needles made of either stainless steel (ferromagnetic) or paramagnetic platinum/iridium alloy. We simulated an ioMRI session with gel and measured the temperature increase with optical fibers. We measured the force that an electrode experiences in the magnetic field. Between 2013 and 2016, we prospectively documented subcutaneous needle electrodes that remained in the patient during intraoperative 3 Tesla ioMRI scans. Results The in vitro testing of the electrodes produced a maximum heating (ΔT = 3.9°C) and force of 0.026 N. We placed 1237 subcutaneous needles in 57 surgical procedures with combined IONM and ioMRI, where needles remained in place during ioMRI. One patient suffered a skin burn on the shoulder. All other electrodes had no side effects. Conclusions We have corroborated the history of safe use for electrodes with 1.5 m cable in a 3T MRI scanner and demonstrated their use. Nevertheless, heating cannot be excluded, as it depends on location and cable placement. When leaving electrodes in place during ioMRI, risks and benefits have to be carefully evaluated for each patient.

Background Patients with neurofibromatosis type 2 and bilateral vestibular schwannoma (VS) are frequently treated surgically for any tumor progression, and often repeated surgery or radiation treatment is even considered. Some VS progression occurs without the development of new clinical symptoms, or it does not progress in size over many years, even in the absence of any specific treatment. Case Description A 61-year-old male patient with neurofibromatosis type 2 presented with bilateral VS. In a long-term follow-up, both had increased in size but also showed bilateral spontaneous regression during an 11-year follow-up period with a “watch-and-wait” strategy. Conclusions We emphasize conservative treatment (“watch and wait”) in older patients even with long-term tumor progression without significant compression-related clinical symptoms.

Background The literature on multiple intracranial aneurysms (MIA) in patients with aneurysmal subarachnoid hemorrhage (aSAH) focuses largely on risk factor analysis and consists essentially of retrospective cohort studies of limited sample size, or studies in populations outside Europe and North America. The purpose of this cohort study was to identify predictors for aneurysm multiplicity and to investigate the anatomic distribution of MIA in a representative Western cohort of patients with aSAH. Methods The Swiss Study of Subarachnoid Hemorrhage (SOS) database includes anonymized data from all tertiary neurovascular facilities in Switzerland. The dataset for 2009–2014 was used to compare characteristics of patients with aSAH and MIA and those with a single intracranial aneurysm (SIA) by means of descriptive and multivariate regression analysis. Results Among 1689 unselected patients with aSAH, 467 had MIA (prevalence, 27.6%). The location of the ruptured index aneurysm was correlated with the probability of finding bystander aneurysms and predicted their likely anatomic distribution. Patients with a ruptured basilar artery aneurysm (odds ratio [OR], 2.11; 95% confidence interval [CI], 1.30–3.44) or a ruptured middle cerebral artery aneurysm (OR, 1.86; 95% CI, 1.35–2.55) were at the greatest risk for having MIA. Larger size of the index aneurysm (OR per 1 mm, 1.03; 95% CI, 1.01–1.06) was also positively correlated with aneurysm multiplicity. Males were less likely than females to have MIA (OR, 0.79; 95% CI, 0.61–1.01). Conclusions In patients with aSAH, the location of the ruptured index aneurysm is correlated with the probability of finding bystander aneurysms, and is predictive of the sites at which bystander aneurysms are most likely to be found.

The aging population in industrialized countries shifts the age limit for neurosurgical interventions toward increasingly older patients. This study investigates whether octogenarians (≥80 years) stand out in outcome and incidence of perioperative complications.Consecutive patients ≥80 years operated on between January 2013 and August 2016 were compared against a control group of patients aged 55-75 years matched by indication for surgery. Status at admission, perioperative complications, functional outcome, and mortality were assessed in a prospective patient registry. Complications were classified in the therapy-oriented Clavien-Dindo grading (CDG) system.We compared 266 octogenarians (median age, 83 years; interquartile range, 81-86 years; 154 men) with 232 controls (median age, 67 years; interquartile range, 60-71 years; 151 men). At follow-up (median, 53 vs. 49 days), median modified Ranking Scale scores were 2 versus 1 and median Karnofsky Performance Status was 80 versus 90; both improved significantly compared to baseline (P0.0001). Only admission Karnofsky Performance Status was significantly associated with clinical outcome at follow-up (odds ratio, 1.05; P0.0001). Pharmacologic treatment (CDG 2) was sufficient in 56% of all complications in octogenarians (controls, 43%). Octogenarians were more prone to complications as an inpatient (36% vs. 28%; P = 0.04) because of a higher incidence of CDG 2 complications (20% vs. 12%; P = 0.02). The rate of complications that required more extensive therapy did not differ significantly between cohorts.Neurosurgery in octogenarians had a similar rate of severe complications, morbidity, and mortality as in matched controls. Therefore, age alone should not serve as a contraindication for neurosurgery.

Objective To present an algorithm based on clinical and radiologic factors, including magnetic resonance imaging (MRI) perfusion/diffusion mismatch (PDM), for the indication of urgent cerebral bypass in patients with acute ischemic stroke. Methods Clinical and radiologic data of 8 consecutive patients undergoing urgent cerebral revascularization for acute ischemic stroke owing to occlusion of internal carotid or middle cerebral artery between 2012 and 2015 were analyzed. All patients either were ineligible for or failed first-line treatment with emergent endovascular revascularization. Indication for urgent bypass was based on clinical worsening and MRI PDM, indicating threat for stroke extension. Clinical outcome was measured using National Institutes of Health Stroke Scale and modified Rankin Scale before and after bypass surgery, at 3-month follow-up, and at last follow-up. Results All patients presented with clinical worsening after initiation of acute stroke treatment. Cerebral revascularization was performed 9.6 hours (SD 9.0) after clinical worsening. All patients had preoperative MRI PDM. No bypass complications, such as anastomosis failure or postoperative hemorrhage, occurred. MRI diffusion ratio before and after bypass was stable or improved in 7 patients and progressed in 1 patient without clinical worsening. MRI PDM and perfusion improved in all 4 patients who underwent postoperative MRI. Clinical outcome was favorable with a median improvement of 7 points on National Institutes of Health Stroke Scale and of 2 points on modified Rankin Scale at last follow-up. Conclusions Based on an algorithm indicating salvageable brain tissue, cerebral revascularization can be safely performed in an emergency setting in a highly selected group of patients with acute ischemic stroke with favorable clinical outcome.

Angiomatous meningioma (AM) is a rare subtype of meningioma characterized by highly vascular tumor tissue comprising predominantly variable sized hyalinized blood vessels. The aim of this study is to evaluate the clinical radiologic features of AM and the long-term prognosis in a single neurosurgical center.A total of 93 patients who underwent surgical resection of AMs between 2003 and 2008 were enrolled for analysis. Clinical information, treatment, and radiologic images were collected and analyzed; follow-up was carried out as well. Expression of estrogen receptor, progesterone receptor, and vascular endothelial growth factor was analyzed by immunohistochemistry.Forty-eight females and 45 males were identified. Forty-four patients (47.31%) manifested as hypersignal in T1-weighted imaging sequences and 68 (73.12%) as hypersignal in T2-weighted imaging, and a characteristic ringlike signal was observed in 28 patients (30.11%). Eighty-one cases (87.10%) showed different degrees of peritumor brain edema and it was significantly correlated with the vascular endothelial growth factor expression (P 0.001). Simpson I resection was achieved in 63 patients (67.74%), grade II in 27 patients (29.03%), and grade III in 3 patients (3.23%). The extent of resection was not associated with the postoperative neurologic function (P = 0.546). Only 4 patients experienced recurrences during the follow-up and these 4 patients were stable until the last follow-up.AMs were a special subtype of meningioma with distinctive radiologic features. AMs manifest benign behavior with a satisfying outcome, which makes Simpson grade II resection an option.

Objective To investigate the influence of meteorological factors on the incidence of intracerebral hemorrhage (ICH). Methods We included 295 ICH admissions between 2005 and 2013. The hourly meteorological parameters considered were surface pressure, temperature, relative humidity, wind gusts, and precipitation. To minimize confounding effects of seasonality, data were analyzed with the following 3 complementary statistical approaches: 1) deviation of daily measure from the 10-year monthly mean at the day of ictus; 2) deviation from monthly average with respect to changes in daily measures between the day of ictus and 2 days before; and 3) evolution of daily measures from 5 days before to 5 days after the ICH occurred. For 1) and 2), the statistical significance of the results was determined with a Monte Carlo simulation combined with a resampling technique (1000×). Results Regarding all patients, no statistically significant and meteorologically meaningful signal could be found. With respect to subgroup-analysis, ICH related to vascular pathologies occurred significantly more frequently at days with especially low relative humidity, whereas an opposite relation was present in patients with cerebral amyloid angiopathy. However, as absolute deviations were small, a strong functional effect is questionable. With respect to seasonal distribution, a greater incidence of ICH could be detected during the cold season, in line with previous reports. Conclusions By using high-quality meteorological data analyzed with a sophisticated and robust statistical method that minimizes the confounding effect of seasonality, no clearly identifiable meteorological influence for the ICH events considered can be found.

To establish an arteriovenous malformation (AVM) grading score for patients with ruptured AVM and associated intracerebral hemorrhage (ICH) to predict clinical outcome.Patient data from January 2006 to December 2013 with newly diagnosed ICH caused by ruptured AVM and a modified Rankin Scale (mRS) score2 before ICH were included for this analysis. Clinical outcome was dichotomized in favorable (mRS score, 0-2) and unfavorable (mRS score, 3-6) to find predictors for outcome and to establish a new score based on the areas under the receiver-operating characteristic curves (AUROC) at 3 months, 1 year, and at last follow-up (mean, 31 months).A total of 67 patients (mean age, 41 years; 66% male) were analyzed including 39 patients with favorable and 28 with unfavorable outcome. Intraventricular hemorrhage (P = 0.048), ICH score (P = 0.003), AVM size (P 0.001), Spetzler-Martin grade (P0.001), nidus structure (P = 0.005), Lawton-Young grade (P = 0.015), and supplemented Spetzler-Martin score (P0.001) were significant predictors for clinical outcome in ruptured AVMs. Based on these results, we created a new score named the AVICH (AVM-related ICH) score, which showed an AUROC of 0.842 compared to 0.789 for the supplemented Spetzler-Martin grading system and 0.703 for the ICH score regarding clinical outcome at last follow-up.Based on the AUROC analysis, the AVICH score predicts outcome of patients with ruptured AVM and associated ICH better than the ICH score, the Spetzler-Martin, or the supplemented Spetzler-Martin grading system. An external validation is needed before the AVICH score is tested in a prospective multicenter cohort.

Objective To determine whether transcranial motor-evoked potential monitoring of the facial nerve (FNMEP) during eloquent tumor resection is feasible in children and can predict both immediate and postoperative facial nerve (FN) function. Methods We included 24 consecutive procedures involving 21 patients (median age 5.5 years, range 5 months to 15 years, 8 female) who were operated on with FNMEP monitoring by the first author in 2013 and 2014. During surgery, we maintained a constant response amplitude by increasing the stimulation intensity and aimed to establish a warning criterion based on the “threshold-level” method. A threshold increase of greater than 20 mA for eliciting the FNMEP in the most reliable facial nerve target muscle was considered to be a prediction of reduced postoperative facial nerve function and consequently, a warning was given to the surgeon. The preoperative and early postoperative function was documented with the House-Brackmann grading system. Results Monitoring of the FNMEP was feasible in all the surgeries in at least one facial nerve target muscle. The orbicularis oris muscle yielded the best result (95% of the trials), followed by the mentalis (87%) and orbicularis oculi muscles (86%). The median stimulation threshold was initially 65 mA (range 40–110 mA) for the FNMEP and 60 mA (15–220 mA) for the motor-evoked potential of the thenar muscles. The FNMEP deterioration showed a sensitivity of 100% for House-Brackmann deterioration and specificity of 74%. Conclusions Intraoperative FNMEP monitoring is feasible and safe in infants and children. We found no evidence that the procedures and thresholds should differ from FNMEP monitoring in adults. FNMEP monitoring provides valid evidence for FN function in pediatric eloquent area surgery; its use is complementary to direct electrical FN stimulation and continuous EMG monitoring of FN target muscles.

Objective To determine interrater agreement in the initial radiologic characterization of ruptured intracranial aneurysms based on computed tomography angiography (CTA) with special emphasis on the rater's level of experience. Methods One junior and one senior rater of 5 high-volume neurovascular tertiary centers evaluated anonymized CTA images of 30 consecutive patients with aneurysmal subarachnoid hemorrhage. Each rater described location, side, size, and morphology in a standardized manner. Interrater variability was analyzed using intraclass correlation and Fleiss' kappa analysis. Results There was a high level of agreement for location (κ = 0.76, 95% confidence interval [CI] 0.74–0.79), side (κ = 0.95, CI 0.91–0.99), maximum diameter (intraclass correlation coefficient [ICC] 0.81, CI 0.70–0.90), and dome (ICC 0.78, CI 0.66–0.88) of intracranial aneurysms. In contrast, a lower level of agreement was observed for aneurysms' neck diameter (ICC 0.39, CI 0.28–0.58), the presence of multiple aneurysms (κ = 0.35, CI 0.30–0.40), and aneurysm morphology (blister κ = 0.11, CI –0.05 to 0.07; fusiform κ = 0.54, CI 0.48–0.60; multilobular, κ = 0.39 CI 0.33–0.45). The interrater agreement in the senior rater group was greater than in the junior rater group. Conclusions Interrater agreement confirms the benefit of CTA as initial diagnostic imaging in ruptured intracranial aneurysms but not for aneurysm morphology and presence of multiple aneurysms. A trend towards greater interrater agreement between more experienced raters was noticed.