Development of a Complication- and Treatment-Aware Prediction Model for Favorable Functional Outcome in Aneurysmal Subarachnoid Hemorrhage Based on Machine Learning

BACKGROUND

Current prognostic tools in aneurysmal subarachnoid hemorrhage (aSAH) are constrained by being primarily based on patient and disease characteristics on admission.

OBJECTIVE

To develop and validate a complication- and treatment-aware outcome prediction tool in aSAH.

METHODS

This cohort study included data from an ongoing prospective nationwide multicenter registry on all aSAH patients in Switzerland (Swiss SOS [Swiss Study on aSAH]; 2009-2015). We trained supervised machine learning algorithms to predict a binary outcome at discharge (modified Rankin scale [mRS] ≤ 3: favorable; mRS 4-6: unfavorable). Clinical and radiological variables on admission ("Early" Model) as well as additional variables regarding secondary complications and disease management ("Late" Model) were used. Performance of both models was assessed by classification performance metrics on an out-of-sample test dataset.

RESULTS

Favorable functional outcome at discharge was observed in 1156 (62.0%) of 1866 patients. Both models scored a high accuracy of 75% to 76% on the test set. The "Late" outcome model outperformed the "Early" model with an area under the receiver operator characteristics curve (AUC) of 0.85 vs 0.79, corresponding to a specificity of 0.81 vs 0.70 and a sensitivity of 0.71 vs 0.79, respectively.

CONCLUSION

Both machine learning models show good discrimination and calibration confirmed on application to an internal test dataset of patients with a wide range of disease severity treated in different institutions within a nationwide registry. Our study indicates that the inclusion of variables reflecting the clinical course of the patient may lead to outcome predictions with superior predictive power compared to a model based on admission data only.

Education, Healthy Ageing and Vaccine Literacy

Importance and Objective: The Covid pandemic is a timely opportunity to try to broaden our understanding of the links between education and health literacy and explore the vaccine-decision process with a view to identifying interventions that will positively influence vaccine uptake.

EVIDENCE

Health and vaccine literacy encompass people's knowledge, motivation, and competence to access, understand, appraise and apply health information in order to make judgements and take decisions in everyday life concerning health care, disease prevention and health promotion.

FINDINGS

Appropriate vaccine communication, which depends greatly on personal and contextual determinants, as well as on societal and environmental circumstances, is essential to reassure people about vaccine efficacy, safety, and possible side effects. However, vaccine confidence is not solely a question of trust in the vaccine's efficacy, safety. and individual protective benefit of vaccination. It also encompasses the mechanism(s) of vaccine activity, immunization schedules, organization and trust in the healthcare system that promotes and delivers the vaccines, and at what costs. When healthcare professionals as science brokers of vaccine knowledge attempt to increase vaccine knowledge and confidence, they must adjust their communication to the educational or health literacy level of their intended audience. Even if their messages are apparently clear and simple, they absolutely need to verify that they are properly understood.

RELEVANCE

Specific vaccine communication training appears essential to increase vaccine communication skills among healthcare providers. Moreover, further randomized controlled studies are warranted to improve vaccine empowerment among different populations, from a variety of educational backgrounds.

Incidence and Outcome of Aneurysmal Subarachnoid Hemorrhage: The Swiss Study on Subarachnoid Hemorrhage (Swiss SOS)

BACKGROUND AND PURPOSE

The purpose of this study was to assess nationwide incidence and outcomes of aneurysmal subarachnoid hemorrhage (aSAH). The Swiss SOS (Swiss Study on Subarachnoid Hemorrhage) was established in 2008 and offers the unique opportunity to provide this data from the point of care on a nationwide level.

METHODS

All patients with confirmed aneurysmal subarachnoid hemorrhage admitted between January 1, 2009 and December 31, 2014, within Switzerland were recorded in a prospective registry. Incidence rates were calculated based on time-matched population data. Admission parameters and outcomes at discharge and at 1 year were recorded.

RESULTS

We recorded data of 1787 consecutive patients. The incidence of aneurysmal subarachnoid hemorrhage in Switzerland was 3.7 per 100 000 persons/y. The number of female patients was 1170 (65.5%). With a follow-up rate of 91.3% at 1 year, 1042 patients (58.8%) led an independent life according to the modified Rankin Scale (0-2). About 1 in 10 patients survived in a dependent state (modified Rankin Scale, 3-5; n=185; 10.4%). Case fatality was 20.1% (n=356) at discharge and 22.1% (n=391) after 1 year.

CONCLUSIONS

The current incidence of aneurysmal subarachnoid hemorrhage in Switzerland is lower than expected and an indication of a global trend toward decreasing admissions for ruptured intracranial aneurysms. Registration: URL: https://www.clinicaltrials.gov. Unique identifier: NCT03245866.

Patterns of care for ruptured aneurysms of the middle cerebral artery: analysis of a Swiss national database (Swiss SOS)

OBJECTIVE

The objective of this study was to determine patterns of care and outcomes in ruptured intracranial aneurysms (IAs) of the middle cerebral artery (MCA) in a contemporary national cohort.

METHODS

The authors conducted a retrospective analysis of prospective data from a nationwide multicenter registry of all aneurysmal subarachnoid hemorrhage (aSAH) cases admitted to a tertiary care neurosurgical department in Switzerland in the years 2009-2015 (Swiss Study on Aneurysmal Subarachnoid Hemorrhage [Swiss SOS]). Patterns of care and outcomes at discharge and the 1-year follow-up in MCA aneurysm (MCAA) patients were analyzed and compared with those in a control group of patients with IAs in locations other than the MCA (non-MCAA patients). Independent predictors of a favorable outcome (modified Rankin Scale score ≤ 3) were identified, and their effect size was determined.

RESULTS

Among 1866 consecutive aSAH patients, 413 (22.1%) harbored an MCAA. These MCAA patients presented with higher World Federation of Neurosurgical Societies grades (p = 0.007), showed a higher rate of concomitant intracerebral hemorrhage (ICH; 41.9% vs 16.7%, p < 0.001), and experienced delayed cerebral ischemia (DCI) more frequently (38.9% vs 29.4%, p = 0.001) than non-MCAA patients. After adjustment for confounders, patients with MCAA were as likely as non-MCAA patients to experience DCI (aOR 1.04, 95% CI 0.74-1.45, p = 0.830). Surgical treatment was the dominant treatment modality in MCAA patients and at a significantly higher rate than in non-MCAA patients (81.7% vs 36.7%, p < 0.001). An MCAA location was a strong independent predictor of surgical treatment (aOR 8.49, 95% CI 5.89-12.25, p < 0.001), despite statistical adjustment for variables traditionally associated with surgical treatment, such as (space-occupying) ICH (aOR 1.73, 95% CI 1.23-2.45, p = 0.002). Even though MCAA patients were less likely to die during the acute hospitalization (aOR 0.52, 0.30-0.91, p = 0.022), their rate of a favorable outcome was lower at discharge than that in non-MCAA patients (55.7% vs 63.7%, p = 0.003). At the 1-year follow-up, 68.5% and 69.6% of MCAA and non-MCAA patients, respectively, had a favorable outcome (p = 0.676).

CONCLUSIONS

Microsurgical occlusion remains the predominant treatment choice for about 80% of ruptured MCAAs in a European industrialized country. Although patients with MCAAs presented with worse admission grades and greater rates of concomitant ICH, in-hospital mortality was lower and long-term disability was comparable to those in patients with non-MCAA.

Visualization of White Matter Fiber Tracts of Brain Tissue Sections With Wide-Field Imaging Mueller Polarimetry

Identification of white matter fiber tracts of the brain is crucial for delineating the tumor border during neurosurgery. A custom-built Mueller polarimeter was used in reflection configuration for the wide-field imaging of thick sections of fixed human brain and fresh calf brain. The maps of the azimuth of the fast optical axis of linear birefringent medium reconstructed from the experimental Mueller matrix images of the specimen by applying a non-linear data compression algorithm showed a strong correlation with the silver-stained sample histology image, which is the gold standard for ex-vivo brain fiber tract visualization. The polarimetric maps of fresh calf brain tissue demonstrated the same trends in the depolarization, the scalar retardance and the azimuth of the fast optical axis as seen in fixed human brain tissue. Thus, label-free imaging Mueller polarimetry shows promise as an efficient intra-operative modality for the visualization of healthy brain white matter fiber tracts, which could improve the accuracy of tumor border detection and, ultimately, patient outcomes.

Exploring Novel Funding Strategies for Innovative Medical Research: The HORAO Crowdfunding Campaign

Background

The rise of the internet and social media has boosted online crowdfunding as a novel strategy to raise funds for kick-starting projects, but it is rarely used in science.

Objective

We report on an online crowdfunding campaign launched in the context of the neuroscience project HORAO. The aim of HORAO was to develop a noninvasive real-time method to visualize neuronal fiber tracts during brain surgery in order to better delineate tumors and to identify crucial cerebral landmarks. The revenue from the crowdfunding campaign was to be used to sponsor a crowdsourcing campaign for the HORAO project.

Methods

We ran a 7-week reward-based crowdfunding campaign on a national crowdfunding platform, offering optional material and experiential rewards in return for a contribution toward raising our target of Swiss francs (CHF) 50,000 in financial support (roughly equivalent to US $50,000 at the time of the campaign). We used various owned media (websites and social media), as well as earned media (press releases and news articles) to raise awareness about our project.

Results

The production of an explanatory video took 60 hours, and 31 posts were published on social media (Facebook, Instagram, and Twitter). The campaign raised a total of CHF 69,109. Approximately half of all donations came from donors who forwent a reward (CHF 28,786, 48.74%); the other half came from donors who chose experiential and material rewards in similar proportions (CHF 14,958, 25.33% and CHF 15,315.69, 25.93%, respectively). Of those with an identifiable relationship to the crowdfunding team, patients and their relatives contributed the largest sum (CHF 17,820, 30.17%), followed by friends and family (CHF 9288, 15.73%) and work colleagues (CHF 6028, 10.21%), while 43.89% of funds came from donors who were either anonymous or had an unknown relationship to the crowdfunding team. Patients and their relatives made the largest donations, with a median value of CHF 200 (IQR 90).

Conclusions

Crowdfunding proved to be a successful strategy to fund a neuroscience project and to raise awareness of a specific clinical problem. Focusing on potential donors with a personal interest in the issue, such as patients and their relatives in our project, is likely to increase funding success. Compared with traditional grant applications, new skills are needed to explain medical challenges to the crowd through video messages and social media.

Absence of pontine perforators in vertebrobasilar dolichoectasia on ultra-high resolution cone-beam computed tomography

Background

Vertebrobasilar dolichoectasia (VBDE) is a rare type of non-saccular intracranial aneurysm, with poor natural history and limited effective treatment options. Visualizing neurovascular microanatomy in patients with VBDE has not been previously reported, but may yield insight into the pathology, and provide important information for treatment planning.

Objective

To carry out a retrospective analysis of ultra-high resolution cone-beam computed tomography (UHR-CBCT) in patients with fusiform basilar aneurysms, visualizing neurovascular microanatomy of the posterior circulation with a special focus on the pontine perforators.

Methods

UHR-CBCT was performed in seven patients (mean age 59 years; two female) with a VBDE, and in 14 control patients with unrelated conditions.

Results

The mean maximum diameter of the fusiform vessel segment was 28 mm (range 19–36 mm), and the mean length of the segment was 39 mm (range 15–50 mm). In all patients with VBDE, UHR-CBCT demonstrated an absence of perforating arteries in the fusiform arterial segment and a mean of 3.7 perforators arising from the unaffected vessel segment. The network of interconnected superficial circumferential pontine arteries (brainstem vasocorona) were draping around the aneurysm sac. In controls, a mean of 3.6, 2.5, and 1.2 perforators were demonstrated arising from the distal, mid-, and proximal basilar artery, respectively.

Conclusions

The absence of pontine perforators in the fusiform vessel segment of VBDE is counterbalanced by recruitment of collateral flow from pontine perforators arising from the unaffected segment of the basilar artery, as well as collaterals arising from the anterior inferior cerebellar artery/posterior inferior cerebellar artery and superior cerebellar artery. These alternative routes supply the superficial brainstem arteries (brainstem vasocorona) and sustain brainstem viability. Our findings might have implications for further treatment planning.

Augmented Reality in Superficial Temporal Artery to Middle Cerebral Artery Bypass Surgery: Technical Note

BACKGROUND

Augmented reality (AR) applied to surgery refers to the virtual superimposition of computer-generated anatomical information on the surgical field. AR assistance in extracranial-intracranial (EC-IC) bypass revascularization surgery has been reported to be a helpful technical adjunct.

OBJECTIVE

To describe our experience of using AR in superficial temporal artery to middle cerebral artery (STA-MCA) bypass surgery with the additional implementation of new technical processes to improve the safety and efficacy of the procedure.

METHODS

Data sets from preoperative imaging were loaded and fused in a single 3-dimensional matrix using the neuronavigation system. Anatomical structures of interest (the STA, a selected M4 branch of the MCA, the middle meningeal artery [MMA], and the primary motor cortex [PMC]) were segmented. After the registration of the patient and the operating microscope, the structures of interest were projected into the eyepiece of the microscope and superimposed onto the patient's head, creating the AR surgical field.

RESULTS

AR was shown to be useful in patients undergoing EC-IC bypass revascularization, mostly during the following 4 surgical steps: (1) microsurgical dissection of the donor vessel (STA); (2) tailoring the craniotomy above the recipient vessel (M4 branch of the MCA); (3) tailoring the craniotomy to spare the MMA; and (4) tailoring the craniotomy and the anastomosis to spare the PMC.

CONCLUSION

AR assistance in EC-IC bypass revascularization is a versatile technical adjunct for helping surgeons to ensure the safety and efficacy of the procedure.

Predicting Successful Low Vision Rehabilitation with Telescopic Spectacles

Although telescopic spectacles magnify the retinal image and should improve functional vision, many low vision patients are unable to use them. The authors found that involuntary head movements and the reduction of acuity with imposed head motion differentiated successful from unsuccessful telescope users and that success was related to the age at which telescopes were first used.

Somatosensory Evoked Potential and Transcranial Doppler Monitoring to Guide Shunting in Carotid Endarterectomy

OBJECTIVE

 Clamping of the internal carotid artery (ICA) during carotid endarterectomy (CEA) is a critical step. In our neurosurgical department, CEAs are performed with transcranial Doppler (TCD) and somatosensory evoked potential (SEP) monitoring with a 50% flow velocity/amplitude decrement warning criteria for shunting. The aim of our study was to evaluate our protocol with immediate neurologic deficits after surgery for the primary end point.

METHODS

 This is a single-center retrospective cohort study of symptomatic and asymptomatic ICA stenosis patients from January 2012 to June 2015. Only those cases in which CEA was performed with both modalities (TCD and SEP) were included. The Mann-Whitney U test was applied to evaluate TCD and SEP ratios based on immediate postoperative neurologic deficits.

RESULTS

 A total of 144 patients were included, 120 (83.3%) with symptomatic ICA stenosis. The primary end point was met by six patients (4.2%); all of them were patients with a symptomatic ICA stenosis. The stroke and death rate was 1.4%. Ratios of SEP amplitudes demonstrated significant differences between patients with and without an immediate postoperative neurologic deficit at the time of ICA clamping (p = 0.005), ICA clamping at 10 minutes (p = 0.044), and ICA reperfusion (p = 0.005). Ratios of TCD flow velocity showed no significant difference at all critical steps.

CONCLUSION

 In this retrospective series of simultaneous TCD and SEP monitoring during CEA surgery of predominantly symptomatic ICA stenosis patients, the stroke and death rate was 1.4%. SEP seemed to be superior to TCD in predicting the need for an intraoperative shunt and for predicting temporary postoperative deficits. Further prospective studies are needed.

Nimodipine-Induced Blood Pressure Changes Can Predict Delayed Cerebral Ischemia

Background: Early diagnosis of delayed cerebral ischemia (DCI) in patients after aneurysmal subarachnoid hemorrhage (aSAH) still poses a leading problem in neurointensive care. The aim of this study was to analyze the effect of oral Nimodipine administration on systemic blood pressure in patients with evolving DCI compared to patients without DCI.

Methods: Systolic (SBP), mean (MAP), and diastolic (DBP) blood pressures were analyzed at the time of Nimodipine administration and additionally 30, 60, and 120 min thereafter on days 1, 3, and 5 after aSAH. Additionally, the 24 h period preceding DCI and in patients without DCI day 10 after aSAH were analyzed. Statistical analysis was performed for SBP, MAP and DBP at time of Nimodipine administration and for the maximal drop in blood pressure after Nimodipine administration.

Results: Thirty patients with aSAH were retrospectively analyzed with 17 patients developing DCI (“DCI”) and 13 patients who did not (“Non-DCI”). DCI patients showed a more pronounced rise in MAP and DBP over the examined time period as well as a higher decrease in SBP following Nimodipine administration. A fall of 18 mmHg in SBP after Nimodipine administration showed a sensitivity of 82.4% and specificity of 92.3% for occurrence of DCI.

Conclusion: An increase of MAP and DBP after aSAH and a heightened sensitivity to Nimodipine administrations may serve as additional biomarkers for early detection of evolving DCI.

Bleeding risk of cerebral cavernous malformations in patients on β-blocker medication: a cohort study

OBJECTIVE

Cerebral cavernous malformations (CCMs) are frequently diagnosed vascular malformations of the brain. Although most CCMs are asymptomatic, some can be responsible for intracerebral hemorrhage or seizures. In selected cases, microsurgical resection is the preferred treatment option. Treatment with the unselective β-blocker propranolol has been presumed to stabilize and eventually lead to CCM size regression in a limited number of published case series; however, the underlying mechanism and evidence for this effect remain unclear. The aim of this study was to investigate the risk for CCM-related hemorrhage in patients on long-term β-blocker medication.

METHODS

A single-center database containing data on patients harboring CCMs was retrospectively interrogated for a time period of 35 years. The database included information about hemorrhage and antihypertensive medication. Descriptive and survival analyses were performed, focusing on the risk of hemorrhage at presentation and during follow-up (first or subsequent hemorrhage) in patients on long-term β-blocker medication versus those who were not. Follow-up was censored at the first occurrence of new hemorrhage, surgery, or the last clinical review. For purposes of this analysis, the β-blocker group was divided into the following main subgroups: any β-blocker, β1-selective β-blocker, and any unselective β-blocker.

RESULTS

Of 542 CCMs among 408 patients, 81 (14.9%) were under treatment with any β-blocker; 65 (12%) received β1-selective β-blocker, and 16 (3%) received any unselective β-blocker. One hundred thirty-six (25.1%) CCMs presented with hemorrhage at diagnosis. None of the β-blocker groups was associated with a lower risk of hemorrhage at the time of diagnosis in a univariate descriptive analysis (any β-blocker: p = 0.64, β1-selective: p = 0.93, any unselective β-blocker: p = 0.25). Four hundred ninety-six CCMs were followed up after diagnosis and included in the survival analysis, for a total of 1800 lesion-years. Follow-up hemorrhage occurred in 36 (7.3%) CCMs. Neither univariate descriptive nor univariate Cox proportional-hazards regression analysis showed a decreased risk for follow-up hemorrhage under treatment with β-blocker medication (any β-blocker: p = 0.70, HR 1.19, 95% CI 0.49-2.90; β1-selective: p = 0.78, HR 1.15, 95% CI 0.44-3.00; any unselective β-blocker: p = 0.76, HR 1.37, 95% CI 0.19-10.08). Multivariate Cox proportional-hazards regression analysis including brainstem location, hemorrhage at diagnosis, age, and any β-blocker treatment showed no reduced risk for follow-up hemorrhage under any β-blocker treatment (p = 0.53, HR 1.36, 95% CI 0.52-3.56).

CONCLUSIONS

In this retrospective cohort study, β-blocker medication does not seem to be associated with a decreased risk of CCM-related hemorrhage at presentation or during follow-up.