Clinical Outcome Prediction of Early Brain Injury in Aneurysmal Subarachnoid Hemorrhage: the SHELTER-Score

BACKGROUND

Despite intensive research on preventing and treating vasospasm and delayed cerebral ischemia in aneurysmal subarachnoid hemorrhage (aSAH), mortality and morbidity rates remain high. Early brain injury (EBI) has emerged as possibly the major significant factor in aSAH pathophysiology, emphasizing the need to investigate EBI-associated clinical events for improved patient management and decision-making. This study aimed to identify early clinical and radiological events within 72 h after aSAH to develop a conclusive predictive EBI score for clinical practice.

METHODS

This retrospective analysis included 561 consecutive patients with aSAH admitted to our neurovascular center between 01/2014 and 09/2022. Fourteen potential predictors occurring within the initial 72 h after hemorrhage were analyzed. The modified Rankin Scale (mRS) score at 6 months, discretized to three levels (0-2, favorable; 3-5, poor; 6, dead), was used as the outcome variable. Univariate ordinal regression ranked predictors by significance, and forward selection with McFadden's pseudo-R2 determined the optimal set of predictors for multivariate proportional odds logistic regression. Collinear parameters were excluded, and fivefold cross-validation was used to avoid overfitting.

RESULTS

The analysis resulted in the Subarachnoid Hemorrhage Associated Early Brain Injury Outcome Prediction score (SHELTER-score), comprising seven clinical and radiological events: age (0-4 points), World Federation of Neurosurgical Societies (0-2.5 points), cardiopulmonary resuscitation (CPR) (2 points), mydriasis (1-2 points), midline shift (0.5-1 points), early deterioration (1 point), and early ischemic lesion (2 points). McFadden's pseudo-R2 = 0.339, area under the curve for death or disability 0.899 and 0.877 for death. A SHELTER-score below 5 indicated a favorable outcome (mRS 0-2), 5-6.5 predicted a poor outcome (mRS 3-5), and ≥ 7 correlated with death (mRS 6) at 6 months.

CONCLUSIONS

The novel SHELTER-score, incorporating seven clinical and radiological features of EBI, demonstrated strong predictive performance in determining clinical outcomes. This scoring system serves as a valuable tool for neurointensivists to identify patients with poor outcomes and guide treatment decisions, reflecting the great impact of EBI on the overall outcome of patients with aSAH.

Revisiting the WFNS Score: Native Computed Tomography Imaging Improves Identification of Patients With "False Poor Grade" Aneurysmal Subarachnoid Hemorrhage

BACKGROUND AND OBJECTIVES

In patients suffering from aneurysmal subarachnoid hemorrhage (aSAH), the optimal time to determine the World Federation of Neurosurgical Societies (WFNS) score remains controversial because of possible confounding factors. Goals of this study were (1) to analyze the most sensitive timepoint to determine the WFNS score in patients with aSAH and (2) to evaluate the impact of initial native computed tomography (CT) imaging on reducing the mismatch of "false poor grade" patients.

METHODS

We retrospectively analyzed daily WFNS scores from admission until day 7 in 535 aSAH patients and evaluated their predictive value for the modified Rankin Scale at discharge and 6 months postbleeding. Patients with an initial WFNS score of IV-V who showed improvement to a WFNS score of I-II within the first 7 days (even short-term) were defined as "false poor grade" patients. We tried to identify the "false poor grade" patients using parameters of the initial native CT imaging.

RESULTS

Later determination of the WFNS score (day 1 vs 7; pseudo-R 2 = 0.13 vs 0.21) increasingly improved its predictive value for neurological outcome at discharge ( P < .001). We identified 39 "false poor grade" patients who had significantly better outcomes than "real poor grade" patients (N = 220) (modified Rankin Scale-discharge: 0-2, 56% vs 1%, P < .001; 3-5: 41% vs 56%, P = .12; 6: 3% vs 43%, P < .001). "False poor grade" patients differed significantly in initial CT parameters. A predictive model called "initial CT WFNS" ( ICT WFNS) was developed, incorporating SEBES, Hijdra score, and LeRoux score (sensitivity = 0.95, specificity = 0.84, accuracy = 0.859, F1 = 0.673). ICT WFNS scores of ≤4.6 classified patients as "false poor grade."

CONCLUSION

The initial WFNS score may misclassify a subgroup of patients with aSAH as poor grade, which can be avoided by later determination of the WFNS score, at days 3-4 losing its usefulness. Alternatively, the initial WFNS score can be improved in its predictive value, especially in poor-grade patients, using criteria from the initial native CT imaging, such as the Hijdra, LeRoux, and Subarachnoid Hemorrhage Early Brain Edema score, combined in the ICT WFNS score with even higher predictive power.

Intraoperative Videogrammetry and Photogrammetry for Photorealistic Neurosurgical 3-Dimensional Models Generated Using Operative Microscope: Technical Note

BACKGROUND AND OBJECTIVES

Intraoperative orientation during microsurgery has a prolonged learning curve among neurosurgical residents. Three-dimensional (3D) understanding of anatomy can be facilitated with realistic 3D anatomic models created from photogrammetry, where a series of 2-dimensional images is converted into a 3D model. This study implements an algorithm that can create photorealistic intraoperative 3D models to exemplify important steps of the operation, operative corridors, and surgical perspectives.

METHODS

We implemented photograph-based and video-based scanning algorithms for uptakes using the operating room (OR) microscope, targeted for superficial structures, after surgical exposure, and deep operative corridors, in cranial microsurgery. The algorithm required between 30-45 photographs (superficial scanning), 45-65 photographs (deep scanning), or approximately 1 minute of video recording of the entire operative field to create a 3D model. A multicenter approach in 3 neurosurgical departments was applied to test reproducibility and refine the method.

RESULTS

Twenty-five 3D models were created of some of the most common neurosurgical approaches-frontolateral, pterional, retrosigmoid, frontal, and temporal craniotomy. The 3D models present important steps of the surgical approaches and allow rotation, zooming, and panning of the model, enabling visualization from different surgical perspectives. The superficial and medium depth structures were consistently presented through the 3D models, whereas scanning of the deepest structures presented some technical challenges, which were gradually overcome with refinement of the image capturing process.

CONCLUSION

Intraoperative photogrammetry is an accessible method to create 3D educational material to show complex anatomy and demonstrate concepts of intraoperative orientation. Detailed interactive 3D models, displaying stepwise surgical case-based anatomy, can be used to help understand details of the operative corridor. Further development includes refining or automatization of image acquisition intraoperatively and evaluation of other applications of the resulting 3D models in training and surgical planning.

CLR (C-Reactive Protein to Lymphocyte Ratio) Served as a Promising Predictive Biomarker for Cerebral Vasospasm in Aneurysmal Subarachnoid Hemorrhage (aSAH): A Retrospective Cohort Study

Background: Subarachnoid hemorrhage is a devastating disease. Even after state-of-the-art treatment patients suffer from complications, including cerebral vasospasm (CVS), delayed cerebral ischemia (DCI), and chronic hydrocephalus (CH) following aneurysmal subarachnoid hemorrhage (aSAH). The aim of our study is to identify the predictive value of the C-reactive protein to lymphocyte ratio (CLR) for neurological functional outcome and complications after aSAH. Methods: We retrospectively analyzed a total of 166 aSAH patients who met the inclusion criteria enrolled in our study. Multivariate logistic regression analyses were performed to evaluate the independent risk factors. The predictive value of different models was compared by calculating the areas under the receiver operating characteristic (ROC) curve. Results: On-admission levels of CLR in patients with poor outcomes (6 months mRS 3-6), CVS, DCI, and CH were significantly higher than those in patients with good outcomes (6 months mRS 0-2), non-CVS, non-DCI, and non-CH. Multivariate logistic regression analysis revealed that admission CLR was independently associated with CVS (OR [95% CI] 2.116 [1.507-2.971]; p < 0.001), and DCI (OR [95% CI] 1.594 [1.220-2.084]; p = 0.001). In ROC analysis, the area under the curve (AUC) of CLR for poor outcomes (6 months mRS 3-6), CVS, DCI, and CH prediction were (AUC [95% CI] 0.639 [0.555-0.724]; p = 0.002), (AUC [95% CI] 0.834 [0.767-0.901]; p < 0.001), (AUC [95% CI] 0.679 [0.581-0.777]; p < 0.001), and (AUC [95% CI] 0.628 [0.543-0.713]; p = 0.005) revealing that admission CLR had a favorable predictive value for CVS after aSAH. The sensitivity and specificity of admission CLR for CVS prediction were 77.1% and 75.4%. On-admission CLR of 0.757 mg × 10-6 was identified as the best cutoff threshold to discriminate between CVS and non-CVS (CVS: CLR < 0.757 mg × 10-6 11/100 [11.0%] vs. CLR ≥ 0.757 mg × 10-6 37/66 [56.1%]; p < 0.001). Conclusions: High levels of on-admission CLR serve as an independent risk factor for CVS and DCI after aSAH. Admission CLR is an easy-to-quantify laboratory parameter that efficiently predicts the CVS after aSAH, which can provide some guidance for clinicians to evaluate for possible progression and treatment strategies in patients with aSAH.

Evaluation of FRESH scores in predicting outcome and quality of life after aneurysmal subarachnoid haemorrhage in a European patient cohort

BACKGROUND

Despite aneurysmal subarachnoid haemorrhage (aSAH) patients often experiencing physical and mental disabilities impacting their quality of life (QoL), routine assessment of long-term QoL data and predictive tools are limited. This study evaluates the newly developed "functional recovery expected after subarachnoid haemorrhage" (FRESH) scores with long-term outcomes and QoL in European aSAH patients.

METHODS

FRESH, FRESH-cog, and FRESH-quol scores were retrospectively obtained from aSAH patients. Patients were contacted, and the modified Rankin Scale (mRS), extended short form-36 (SF-36), and telephone interview for cognitive status (TICS) were collected and performed. The prognostic and empirical outcomes were compared.

RESULTS

Out of 374 patients, 171 patients (54.1%) completed the SF-36, and 154 patients completed the TICS. The SF-36 analysis showed that 32.7% had below-average physical component summary (PCS) scores, and 39.8% had below-average mental component summary (MCS) scores. There was no significant correlation between the FRESH score and PCS (p = 0.09736), MCS (p = 0.1796), TICS (p = 0.7484), or mRS 10-82 months (average 46 months) post bleeding (p = 0.024), respectively. There was also no significant correlation found for "FRESH-cog vs. TICS" (p = 0.0311), "FRESH-quol vs. PCS" (p = 0.0204), "FRESH-quol vs. MCS" (p = 0.1361) and "FRESH-quol vs. TICS" (p = 0.1608).

CONCLUSIONS

This study found no correlation between FRESH scores and validated QoL tools in a European population of aSAH patients. The study highlights the complexity of reliable long-term QoL prognostication in aSAH patients and emphasises the need for further prospective research to also focus on QoL as an important outcome parameter.

Combined use of 3D printing and mixed reality technology for neurosurgical training: getting ready for brain surgery

OBJECTIVE

Learning surgical skills is an essential part of neurosurgical training. Ideally, these skills are acquired to a sufficient extent in an ex vivo setting. The authors previously described an in vitro brain tumor model, consisting of a cadaveric animal brain injected with fluorescent agar-agar, for acquiring a wide range of basic neuro-oncological skills. This model focused on haptic skills such as safe tissue ablation technique and the training of fluorescence-based resection. As important didactical technologies such as mixed reality and 3D printing become more readily available, the authors developed a readily available training model that integrates the haptic aspects into a mixed reality setup.

METHODS

The anatomical structures of a brain tumor patient were segmented from medical imaging data to create a digital twin of the case. Bony structures were 3D printed and combined with the in vitro brain tumor model. The segmented structures were visualized in mixed reality headsets, and the congruence of the printed and the virtual objects allowed them to be spatially superimposed. In this way, users of the system were able to train on the entire treatment process from surgery planning to instrument preparation and execution of the surgery.

RESULTS

Mixed reality visualization in the joint model facilitated model (patient) positioning as well as craniotomy and the extent of resection planning respecting case-dependent specifications. The advanced physical model allowed brain tumor surgery training including skin incision; craniotomy; dural opening; fluorescence-guided tumor resection; and dura, bone, and skin closure.

CONCLUSIONS

Combining mixed reality visualization with the corresponding 3D printed physical hands-on model allowed advanced training of sequential brain tumor resection skills. Three-dimensional printing technology facilitates the production of a precise, reproducible, and worldwide accessible brain tumor surgery model. The described model for brain tumor resection advanced regarding important aspects of skills training for neurosurgical residents (e.g., locating the lesion, head position planning, skull trepanation, dura opening, tissue ablation techniques, fluorescence-guided resection, and closure). Mixed reality enriches the model with important structures that are difficult to model (e.g., vessels and fiber tracts) and advanced interaction concepts (e.g., craniotomy simulations). Finally, this concept demonstrates a bridging technology toward intraoperative application of mixed reality.

Novel Insights into Pathophysiology of Delayed Cerebral Ischemia: Effects of Current Rescue Therapy on Microvascular Perfusion Heterogeneity

General microvascular perfusion and its heterogeneity are pathophysiological features of delayed cerebral ischemia (DCI) that are gaining increasing attention. Recently, CT perfusion (CTP) imaging has made it possible to evaluate them radiologically using mean transit time (MTT) and its heterogeneity (measured by cvMTT). This study evaluates the effect of multimodal rescue therapy (intra-arterial nimodipine administration and elevation of blood pressure) on MTT and cvMTT during DCI in aneurysmal subarachnoid haemorrhage (aSAH) patients. A total of seventy-nine aSAH patients who underwent multimodal rescue therapy between May 2012 and December 2019 were retrospectively included in this study. CTP-based perfusion impairment (MTT and cvMTT) on the day of DCI diagnosis was compared with follow-up CTP after initiation of combined multimodal therapy. The mean MTT was significantly reduced in the follow-up CTP compared to the first CTP (3.7 ± 0.7 s vs. 3.3 ± 0.6 s; p < 0.0001). However, no significant reduction of cvMTT was observed (0.16 ± 0.06 vs. 0.15 ± 0.06; p = 0.44). Mean arterial pressure was significantly increased between follow-up and first CTP (98 ± 17 mmHg vs. 104 ± 15 mmHg; p < 0.0001). The combined multimodal rescue therapy was effective in addressing the general microvascular perfusion impairment but did not affect the mechanisms underlying microvascular perfusion heterogeneity. This highlights the need for research into new therapeutic approaches that also target these pathophysiological mechanisms of DCI.

Photogrammetry Applied to Neurosurgery: A Literature Review

Photogrammetry refers to the process of creating 3D models and taking measurements through the use of photographs. Photogrammetry has many applications in neurosurgery, such as creating 3D anatomical models and diagnosing and evaluating head shape and posture deformities. This review aims to summarize the uses of the technique in the neurosurgical practice and showcase the systems and software required for its implementation. A literature review was done in the online database PubMed. Papers were searched using the keywords "photogrammetry", "neurosurgery", "neuroanatomy", "craniosynostosis" and "scoliosis". The identified articles were later put through primary (abstracts and titles) and secondary (full text) screening for eligibility for inclusion. In total, 86 articles were included in the review from 315 papers identified. The review showed that the main uses of photogrammetry in the field of neurosurgery are related to the creation of 3D models of complex neuroanatomical structures and surgical approaches, accompanied by the uses for diagnosis and evaluation of patients with structural deformities of the head and trunk, such as craniosynostosis and scoliosis. Additionally, three instances of photogrammetry applied for more specific aims, namely, cervical spine surgery, skull-base surgery, and radiosurgery, were identified. Information was extracted on the software and systems used to execute the method. With the development of the photogrammetric method, it has become possible to create accurate 3D models of physical objects and analyze images with dedicated software. In the neurosurgical setting, this has translated into the creation of anatomical teaching models and surgical 3D models as well as the evaluation of head and spine deformities. Through those applications, the method has the potential to facilitate the education of residents and medical students and the diagnosis of patient pathologies.

Initial Temporal Muscle Thickness and Area: Poor Predictors of Neurological Outcome in Aneurysmal Subarachnoid Hemorrhage in a Central European Patient Cohort

The temporalis muscle area (TMA) has been proclaimed as a surrogate parameter for estimating skeletal muscle mass. Pilot studies in Asian populations suggested temporal muscle thickness (TMT) and TMA as prognostic factors for neurological outcomes in aneurysmal subarachnoid hemorrhage (aSAH) patients. This study aimed to validate these findings in a larger European patient cohort. We retrospectively analyzed age, sex, aneurysm location, treatment, World Federation of Neurosurgical Societies (WFNS) grade, Fisher score, and modified Rankin Score (mRS) at six months in patients with aSAH. TMT and TMA measurements were obtained from initial native CT scans. Logistic regression with the dichotomized six-month mRS as the outcome incorporating TMT, weighted average of TMT, or TMA as predictors was performed. Of the included 478 patients, 66% were female, the mean age was 56, and 48% of patients had an mRS of three to six after six months. The mean TMT at the level of the Sylvian fissure was 5.9 (±1.7) mm in males and 4.8 (±1.8) mm in females. The mean TMA was 234.5 (±107.9) mm2 in females and 380 (±134.1) mm2 in males. WFNS grade (p < 0.001), Fisher score (p < 0.001), and age (p < 0.05) correlated significantly with the mRS after six months. No correlation was found between mRS after six months and the TMT at the Sylvian fissure (p = 0.3), the weighted average of TMT (p = 0.1), or the TMA (p = 0.1). In this central European patient cohort of 478 individuals, no significant associations were found between TMT/TMA and neurological outcomes following aSAH. Further prospective studies in diverse patient populations are necessary to determine the prognostic value of TMA and TMT in aSAH patients.

Photorealistic 3-Dimensional Models of the Anatomy and Neurosurgical Approaches to the V2, V3, and V4 Segments of the Vertebral Artery

BACKGROUND

The vertebral artery (VA) has a tortuous course subdivided into 4 segments (V1-V4). For neurosurgeons, a thorough knowledge of the 3-dimensional (3D) anatomy at different segments is a prerequisite for safe surgery. New technologies allowing creation of photorealistic 3D models may enhance the anatomic understanding of this complex region.

OBJECTIVE

To create photorealistic 3D models illustrating the anatomy and surgical steps needed for safe neurosurgical exposure of the VA.

METHODS

We dissected 2 latex injected cadaver heads. Anatomic layered dissections were performed on the first specimen. On the second specimen, the two classical approaches to the VA (far lateral and anterolateral) were realized. Every step of dissection was scanned using photogrammetry technology that allowed processing of 3D data from 2-dimensional photographs by a simplified algorithm mainly based on a dedicated mobile phone application and open-source 3D modeling software. For selected microscopic 3D anatomy, we used an operating microscope to generate 3D models.

RESULTS

Classic anatomic (n=17) and microsurgical (n=12) 3D photorealistic models based on cadaver dissections were created. The models allow observation of the spatial relations of each anatomic structure of interest and have an immersive view of the approaches to the V2-V4 segments of the VA. Once generated, these models may easily be shared on any digital device or web-based platforms for 3D visualization.

CONCLUSIONS

Photorealistic 3D scanning technology is a promising tool to present complex anatomy in a more comprehensive way. These 3D models can be used for education, training, and potentially preoperative planning.

Evaluation of MTT Heterogeneity of Perfusion CT Imaging in the Early Brain Injury Phase: An Insight into aSAH Pathopysiology

The concept of early brain injury (EBI) is based on the assumption of a global reduction in brain perfusion following aneurysmal subarachnoid hemorrhage (aSAH). However, the heterogeneity of computed tomography perfusion (CTP) imaging in EBI has not yet been investigated. In contrast, increased mean transit time (MTT) heterogeneity, a possible marker of microvascular perfusion heterogeneity, in the delayed cerebral ischemia (DCI) phase has recently been associated with a poor neurological outcome after aSAH. Therefore, in this study, we investigated whether the heterogeneity of early CTP imaging in the EBI phase is an independent predictor of the neurological outcome after aSAH. We retrospectively analyzed the heterogeneity of the MTT using the coefficient of variation (cvMTT) in early CTP scans (within 24 h after ictus) of 124 aSAH patients. Both linear and logistic regression were used to model the mRS outcome, which were treated as numerical and dichotomized values, respectively. Linear regression was used to investigate the linear dependency between the variables. No significant difference in cvMTT between the patients with and those without EVD could be observed (p = 0.69). We found no correlation between cvMTT in early CTP imaging and initial modified Fisher (p = 0.07) and WFNS grades (p = 0.23). The cvMTT in early perfusion imaging did not correlate significantly with the 6-month mRS for the entire study population (p = 0.15) or for any of the subgroups (without EVD: p = 0.21; with EVD: p = 0.3). In conclusion, microvascular perfusion heterogeneity, assessed by the heterogeneity of MTT in early CTP imaging, does not appear to be an independent predictor of the neurological outcome 6 months after aSAH.

Lateral Approach to the Cervical Spine to Manage Degenerative Cervical Myelopathy and Radiculopathy

BACKGROUND

The cervical lateral approach can enlarge the spinal canal and foramen to achieve an effective neural decompression without needing spine stabilization. For this review, the authors' main objective was to illustrate the rationale, advantages, disadvantages, complications, and pitfalls of this technique, highlighting also areas for future development.

MATERIALS AND METHODS

A Medline via PubMed database search was carried out by using both keywords, namely "cervical oblique corpectomy," "multilevel oblique corpectomy and foraminotomy," and "lateral vertebrectomy," and Medical Subject Headings (MeSH) terms from 1 January 1991, up to 31 December 2021.

RESULTS

The analyzed articles suggested that the use of such a technique has declined over time; only 29 clinical studies met all the inclusion criteria and were retained for data analysis, including 1200 patients undergoing such an approach for the management of degenerative cervical myelopathies (DCMs) or of radiculopathies. The main etiopathogeneses were cervical stenosis, degenerative disk disease, or a mix of them-78% of which had a favorable outcome; the most frequent complications were transient and permanent Horner syndrome in 13.6% and 9.2% of cases, respectively. Long-term stability was reported in 97% of patients.

CONCLUSION

Multilevel cervical oblique vertebrectomy and/or lateral foraminotomy allow wide neural structure decompression and optimal stability given that the physiological spinal motion is preserved.

[Cochlear nerve continuity preservation during retrosigmoid ablative osteotomy of the internal auditory canal for advanced vestibular schwannomas]

The data of 86 patients with retrosigmoid microsurgical resection of vestibular schwannoma in tumor stage Koos II-IV were evaluated. In more than two thirds of the cases it was shown that the cochlear nerve followed the facial nerve, which is easily identified by electroneurography, in recurrent similar patterns in the region of the internal auditory canal. Starting from the fundus, this facilitated early identification and thus preservation of continuity of the cochlear nerve in the course of the internal auditory canal. This was of particular importance when safe functional preservation could not be guaranteed due to tumor size or formation despite intraoperative derivation of somatosenoric potentials, but when the possibility of subsequent hearing rehabilitation with a cochlear implant should be granted. Preoperative MRI sequences gave an indication of the possible nerve courses in some cases, but intraoperative imaging in the internal auditory canal was superior to MRI.

Management of non-vestibular schwannomas in adult patients: a systematic review and consensus statement on behalf of the EANS skull base section. Part I: oculomotor and other rare non-vestibular schwannomas (I, II, III, IV, VI)

BACKGROUND

Non-vestibular schwannomas are relatively rare, with trigeminal and jugular foramen schwannomas being the most common. This is a heterogeneous group which requires detailed investigation and careful consideration to management strategy. The optimal management for these tumours remains unclear, and there are several controversies. The aim of this paper is to provide insight into the main principles defining management and surgical strategy, in order to formulate a series of recommendations.

METHODS

A task force was created by the EANS skull base section along with its members and other renowned experts in the field to generate recommendations for the surgical management of these tumours on a European perspective. To achieve this, the task force performed an extensive systematic review in this field and had discussions within the group. This article is the first of a three-part series describing non-vestibular schwannomas (I, II, III, IV, VI).

RESULTS

A summary of literature evidence was proposed after discussion within the EANS skull base section. The constituted task force dealt with the practice patterns that exist with respect to pre-operative radiological investigations, ophthalmological assessments, optimal surgical and radiotherapy strategies and follow-up management.

CONCLUSION

This article represents the consensually derived opinion of the task force with respect to the treatment of non-vestibular schwannomas. For each of these tumours, the management of these patients is complex, and for those which are symptomatic tumours, the paradigm is shifting towards the compromise between function preservation and progression-free survival.

Management of non-vestibular schwannomas in adult patients: a systematic review and consensus statement on behalf of the EANS skull base section Part III: Lower cranial nerve schwannomas, jugular foramen (CN IX, X, XI) and hypoglossal schwannoma (XII)

BACKGROUND

Non-vestibular schwannomas are relatively rare, with trigeminal and jugular foramen schwannomas being the most common. This is a heterogenous group which requires detailed investigation and careful consideration to management strategy. The optimal management for these tumours remains unclear, and there are several controversies. The aim of this paper is to provide insight into the main principles defining management and surgical strategy, in order to formulate a series of recommendations.

METHODS

A task force was created by the EANS skull base section committee along with its members and other renowned experts in the field to generate recommendations for the surgical management of these tumours on a European perspective. To achieve this, the task force performed an extensive systematic review in this field and had discussions within the group. This article is the third of a three-part series describing non-vestibular schwannomas (IX, X, XI, XII).

RESULTS

A summary of literature evidence was proposed after discussion within the EANS skull base section. The constituted task force dealt with the practice patterns that exist with respect to preoperative radiological investigations, ophthalmological assessments, optimal surgical and radiotherapy strategies and follow-up management.

CONCLUSION

This article represents the consensually derived opinion of the task force with respect to the treatment of non-vestibular schwannomas. For each of these tumours, the management paradigm is shifting towards the compromise between function preservation and progression free survival.

Management of non-vestibular schwannomas in adult patients: a systematic review and consensus statement on behalf of the EANS skull base section Part II: Trigeminal and facial nerve schwannomas (CN V, VII)

BACKGROUND

Non-vestibular schwannomas are relatively rare, with trigeminal and jugular foramen schwannomas being the most common. This is a heterogenous group which requires detailed investigation and careful consideration to management strategy. The optimal management for these tumours remains unclear and there are several controversies. The aim of this paper is to provide insight into the main principles defining management and surgical strategy, in order to formulate a series of recommendations.

METHODS

A task force was created by the EANS skull base section committee along with its members and other renowned experts in the field to generate recommendations for the surgical management of these tumours on a European perspective. To achieve this, the task force performed an extensive systematic review in this field and had discussions within the group. This article is the second of a three-part series describing non-vestibular schwannomas (V, VII).

RESULTS

A summary of literature evidence was proposed after discussion within the EANS skull base section. The constituted task force dealt with the practice patterns that exist with respect to pre-operative radiological investigations, ophthalmological assessments, optimal surgical and radiotherapy strategies, and follow-up management.

CONCLUSION

This article represents the consensually derived opinion of the task force with respect to the treatment of trigeminal and facial schwannoma. The aim of treatment is maximal safe resection with preservation of function. Careful thought is required to select the appropriate surgical approach. Most middle fossa trigeminal schwannoma tumours can be safely accessed by a subtemporal extradural middle fossa approach. The treatment of facial nerve schwannoma remains controversial.

Management of cavernous sinus meningiomas: Consensus statement on behalf of the EANS skull base section

Introduction

The evolution of cavernous sinus meningiomas (CSMs) might be unpredictable and the efficacy of their treatments is challenging due to their indolent evolution, variations and fluctuations of symptoms, heterogeneity of classifications and lack of randomized controlled trials. Here, a dedicated task force provides a consensus statement on the overall management of CSMs.

Research question

To determine the best overall management of CSMs, depending on their clinical presentation, size, and evolution as well as patient characteristics.

Material and methods

Using the PRISMA 2020 guidelines, we included literature from January 2000 to December 2020. A total of 400 abstracts and 77 titles were kept for full-paper screening.

Results

The task force formulated 8 recommendations (Level C evidence). CSMs should be managed by a highly specialized multidisciplinary team. The initial evaluation of patients includes clinical, ophthalmological, endocrinological and radiological assessment. Treatment of CSM should involve experienced skull-base neurosurgeons or neuro-radiosurgeons, radiation oncologists, radiologists, ophthalmologists, and endocrinologists.

Discussion and conclusion

Radiosurgery is preferred as first-line treatment in small, enclosed, pauci-symptomatic lesions/in elderly patients, while large CSMs not amenable to resection or WHO grade II-III are candidates for radiotherapy. Microsurgery is an option in aggressive/rapidly progressing lesions in young patients presenting with oculomotor/visual/endocrinological impairment. Whenever surgery is offered, open cranial approaches are the current standard. There is limited experience reported about endoscopic endonasal approach for CSMs and the main indication is decompression of the cavernous sinus to improve symptoms. Whenever surgery is indicated, the current trend is to offer decompression followed by radiosurgery.

•

A thorough evaluation of cavernous sinus meningiomas by a multidisciplinary team is mandatory.

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Microsurgery should be considered for aggressive lesions in young patients.

•

Extended endoscopic approaches can be effective when combined with radiotherapy.

•

Stereotaxic radiotherapy and stereotaxic radiosurgery offer excellent tumour control in small/asymptomatic lesions .

Surgical management of giant pituitary neuroendocrine tumors: Meta-analysis and consensus statement on behalf of the EANS skull base section

Introduction

The optimal surgical treatment for giant pituitary neuroendocrine tumors(GPitNETs) is debated.

Research question

The aim of this paper is to optimize the surgical management of these patients and to provide a consensus statement on behalf of the EANS Skull Base Section.

Material and methods

We constituted a task force belonging to the EANS skull base committee to define some principles for the management of GPitNETs. A systematic review was performed according to PRISMA guidelines to perform a meta-analysis on surgical series of GPitNETs. Weighted summary rates were obtained for the pooled extent of resection and according to the surgical technique. These data were discussed to obtain recommendations after evaluation of the selected articles and discussion among the experts.

Results

20articles were included in our meta-analysis, for a total of 1263 patients. The endoscopic endonasal technique was used in 40.3% of cases, the microscopic endonasal approach in 34% of cases, transcranial approaches in 18.7% and combined approaches in 7% of cases. No difference in terms of gross total resection (GTR) rate was observed among the different techniques. Pooled GTR rate was 36.6%, while a near total resection (NTR) was possible in 45.2% of cases. Cavernous sinus invasion was associated with a lower GTR rate (OR: 0.061). After surgery, 35% of patients had endocrinological improvement and 75.6% had visual improvement. Recurrent tumors were reported in 10% of cases

Discussion and conclusion

After formal discussion in the working group, we recommend the treatment of G-PitNETs tumors with a more complex and multilobular structure in tertiary care centers. The endoscopic endonasal approach is the first option of treatment and extended approaches should be planned according to extension, morphology and consistency of the lesion. Transcranial approaches play a role in selected cases, with a multicompartmental morphology, subarachnoid invasion and extension lateral to the internal carotid artery and in the management of residual tumor apoplexy.

Surgical treatment of brainstem cavernous malformations: an international Delphi consensus

OBJECTIVE

Indication for surgery in brainstem cavernous malformations (BSCMs) is based on many case series, few comparative studies, and no randomized controlled trials. The objective of this study was to seek consensus about surgical management aspects of BSCM.

METHODS

A total of 29 experts were invited to participate in a multistep Delphi consensus process on the surgical treatment of BSCM.

RESULTS

Twenty-two (76%) of 29 experts participated in the consensus. Qualitative analysis (content analysis) of an initial open-ended question survey resulted in 99 statements regarding surgical treatment of BSCM. By using a multistep survey with 100% participation in each round, consensus was reached on 52 (53%) of 99 statements. These were grouped into 4 categories: 1) definitions and reporting standards (7/14, 50%); 2) general and patient-related aspects (11/16, 69%); 3) anatomical-, timing of surgery-, and BSCM-related aspects (22/37, 59%); and 4) clinical situation-based decision-making (12/32, 38%). Among other things, a consensus was reached for surgical timing, handling of associated developmental venous anomalies, handling of postoperative BSCM remnants, assessment of specific anatomical BSCM localizations, and treatment decisions in typical clinical BSCM scenarios.

CONCLUSIONS

A summary of typical clinical scenarios and a catalog of various BSCM- and patient-related aspects that influence the surgical treatment decision have been defined, rated, and interpreted.

Petroclival meningiomas: update of current treatment and consensus by the EANS skull base section

BACKGROUND

The optimal management of petroclival meningiomas (PCMs) continues to be debated along with several controversies that persist.

METHODS

A task force was created by the EANS skull base section along with its members and other renowned experts in the field to generate recommendations for the management of these tumors. To achieve this, the task force reviewed in detail the literature in this field and had formal discussions within the group.

RESULTS

The constituted task force dealt with the existing definitions and classifications, pre-operative radiological investigations, management of small and asymptomatic PCMs, radiosurgery, optimal surgical strategies, multimodal treatment, decision-making, and patient's counselling.

CONCLUSION

This article represents the consensually derived opinion of the task force with respect to the management of PCMs.

Asymmetry of P1 and vertebral arteries is not related to basilar tip aneurysm development or rupture

OBJECTIVE

Lately, morphological parameters of the surrounding vasculature aside from aneurysm size, specific for the aneurysm location, e.g., posterior cerebral artery angle for basilar artery tip aneurysms, could be identified to correlate with the risk of rupture. We examined further image-based morphological parameters of the aneurysm surrounding vasculature that could correlate with the growth or the risk of rupture of basilar artery tip aneurysms.

METHODS

Data from 83 patients with basilar tip aneurysms (27 not ruptured; 56 ruptured) and 100 control patients were assessed (50 without aneurysms and 50 with aneurysms of the anterior circle of Willis). Anatomical parameters of the aneurysms were assessed and analyzed, as well as of the surrounding vasculature, namely the asymmetry of P1 and the vertebral arteries.

RESULTS

Patients with basilar tip aneurysm showed no significant increase in P1 or vertebral artery asymmetry compared with the control patients or patients with aneurysms of the anterior circulation, neither was there a significant difference in asymmetry between cases with ruptured and unruptured aneurysms. Furthermore, we observed no significant correlations between P1 asymmetry and the aneurysm size or number of lobuli in the aneurysms.

CONCLUSION

We observed no significant difference in aneurysm size, rupture, or lobulation associated with P1 or vertebral artery (surrounding vasculature) asymmetry. Therefore, the asymmetry of the surrounding vessels does not seem to be a promising morphological parameter for the evaluation of probability of rupture and growth in basilar tip aneurysms in future studies.

Association between aneurysm hemodynamics and wall enhancement on 3D vessel wall MRI

OBJECTIVE

Aneurysm wall enhancement (AWE) on 3D vessel wall MRI (VWMRI) has been suggested as an imaging biomarker for intracranial aneurysms (IAs) at higher risk of rupture. While computational fluid dynamics (CFD) studies have been used to investigate the association between hemodynamic forces and rupture status of IAs, the role of hemodynamic forces in unruptured IAs with AWE is poorly understood. The authors investigated the role and implications of abnormal hemodynamics related to aneurysm pathophysiology in patients with AWE in unruptured IAs.

METHODS

Twenty-five patients who had undergone digital subtraction angiography (DSA) and VWMRI studies from September 2016 to September 2017 were included, resulting in 22 patients with 25 IAs, 9 with and 16 without AWE. High-resolution CFD models of hemodynamics were created from DSA images. Univariate and multivariate analyses were performed to investigate the association between AWE and conventional morphological and hemodynamic parameters. Normalized MRI signal intensity was quantified and quantitatively associated with wall shear stresses (WSSs) for the entire aneurysm sac, and in regions of low, intermediate, and high WSS.

RESULTS

The AWE group had lower WSS (p < 0.01) and sac-averaged velocity (p < 0.01) and larger aneurysm size (p < 0.001) and size ratio (p = 0.0251) than the non-AWE group. From multivariate analysis of both hemodynamic and morphological factors, only low WSS was found to be independently associated with AWE. Sac-averaged normalized MRI signal intensity correlated with WSS and was significantly different in regions of low WSS compared to regions of intermediate (p = 0.018) and high (p < 0.001) WSS.

CONCLUSIONS

The presence of AWE was associated with morphological and hemodynamic factors related to rupture risk. Low WSS was found to be an independent predictor of AWE. Our findings support the hypothesis that low WSS in IAs with AWE may indicate a growth and remodeling process that may predispose such aneurysms to rupture; however, a causality between the two cannot be established.

Transcranial Doppler Ultrasound, Perfusion Computerized Tomography, and Cerebral Angiography Identify Different Pathological Entities and Supplement Each Other in the Diagnosis of Delayed Cerebral Ischemia

INTRODUCTION

There is still controversial discussion of the value of transcranial Doppler (TCD) in predicting vasospasms in patients with aneurysmal SAH (aSAH). A newer method of predicting a delayed ischemic deficit (DCI) is CT perfusion (CTP), although it is not quite understood which kind of perfusion deficit is detected by this method since it seems to also identifying microcirculatory disturbances. We compared the TCD and CTP values with angiography and evaluated TCD and CTP changes before and after patients received intra-arterial spasmolytic therapy.

MATERIAL AND METHODS

Retrospective analysis of TCD, CTP, and angiographies of N = 77 patients treated from 2013 to 2016. In 38 patients intra-arterial spasmolysis had been performed, and in these cases TCD and CTP data were compared before and after lysis. Thirty-nine patients had a pathological CTP but no angiographically seen vasospasm.

RESULTS

There was no correlation between the known thresholds of mean transit time (MTT) in CTP and vasospasm or with mean velocities in TCD and vasospasm. After spasmolysis in patients with vasospasms, only the MTT showed significant improvement, whereas TCD velocities and Lindegaard index remained unaffected.

CONCLUSION

TCD and CTP seem to identify different pathological entities of DCI and should be used supplementary in order to identify as many patients as possible with vasospasms after aSAH.

Open Microsurgical Dorsal Root Ganglion Lead Placement

INTRODUCTION

Dorsal root ganglion stimulation (DRG) is a new but well-established neuromodulation technique allowing new indications and superiority to pre-existing stimulation techniques such as spinal cord stimulation in selected pain etiologies. Previous surgical procedures in the implantation area pose a challenge for the percutaneous technique and are therefore considered contraindications for DRG stimulation surgery. We describe the successful open DRG electrode placement in two patients with previous surgeries suffering from severe radiculopathy due to foraminal stenosis.

METHODS

Percutaneous implantation attempts failed and an open laminotomy/foraminotomy followed by open lead placement was performed. Leads and loops were placed under the microscope, lead location was verified by x-ray during surgery. Leads and loops were kept in position with fibrin glue and fibrin sealant patches. No special tool was required for open lead placement.

RESULTS

In both patients, surgery resulted in lead and loop placement resembling the results seen in percutaneous technique. Programming and stimulation results are similar to observations made following percutaneous techniques in one patient significantly lower stimulation amplitudes were necessary. In 18 and 12 months follow-up, respectively, lead location and paresthesia coverage were stable.

CONCLUSION

The option of open electrode placement should be taken into account following unsuccessful percutaneous lead placement. A combination of fibrin sealant patch and fibrin glue may be a good option for stabilization of the lead and specially of the strain relief loops in open placement. Knowledge of basic spinal surgery techniques and experience in percutaneous DRG stimulation is necessary to perform this procedure.

Aneurysmal Subarachnoid Hemorrhage

BACKGROUND

Aneurysmal subarachnoid hemorrhage (SAH) is associated with a mortality of more than 30%. Only about 30% of patients with SAB recover sufficiently to return to independent living.

METHODS

This article is based on a selective review of pertinent literature retrieved by a PubMed search.

RESULTS

Acute, severe headache, typically described as the worst headache of the patient's life, and meningismus are the characteristic manifestations of SAH. Computed tomog raphy (CT) reveals blood in the basal cisterns in the first 12 hours after SAH with approximately 95% sensitivity and specificity. If no blood is seen on CT, a lumbar puncture must be performed to confirm or rule out the diagnosis of SAH. All patients need intensive care so that rebleeding can be avoided and the sequelae of the initial bleed can be minimized. The immediate transfer of patients with acute SAH to a specialized center is crucially important for their outcome. In such centers, cerebral aneurysms can be excluded from the circulation either with an interventional endovascular procedure (coiling) or by microneurosurgery (clipping).

CONCLUSION

SAH is a life-threatening condition that requires immediate diagnosis, transfer to a neurovascular center, and treatment without delay.

Natural History of De Novo Aneurysm Formation in Patients with Treated Aneurysmatic Subarachnoid Hemorrhage: A Ten-Year Follow-Up

BACKGROUND

De novo aneurysm formation after completely occluded aneurysms via clipping or coiling has not been well studied. Although known to occur several years after initial aneurysm management, the natural history of de novo aneurysms is obscure. We investigated the formation of new aneurysms in patients who had previously undergone treatment of intracranial aneurysms.

METHODS

In a retrospective, single-institutional series, eligible patients who had undergone treatment of ruptured cerebral aneurysms from 2000 to 2011 were included. The primary outcome measure was the development of de novo aneurysms during long-term follow-up.

RESULTS

Overall, 130 patients (63% women) who had undergone microsurgical clipping (n = 63; 48.5%) or endovascular coiling (n = 67%; 51.5%) for ruptured aneurysms were included. The average follow-up time for our cohort was 10 ± 2.7 years. De novo aneurysms occurred in 10 of 130 patients (7.7%), with a mean time of 7.9 years for aneurysm detection. No association between the formation of de novo aneurysms and the location of the treated aneurysms, smoking status, hypertension, age, or gender was found. Follow-up imaging studies were performed every 2 years. De novo aneurysms had formed in 2 patients within 2-5 years, 7 patients after 5-10 years, and 1 patient after 10 years of follow-up. In 2 of 10 patients, the de novo aneurysm had ruptured and led to subarachnoid haemorrhage.

CONCLUSION

The rate of de novo aneurysm occurrence was 7.6%, with a mean time to development of 7.9 years. This underscores the significance of long-term monitoring of patients with intracranial aneurysms. In our series, most new aneurysms had occurred after 5 years of follow-up.

Volume of cerebrospinal fluid drainage as a predictor for pretreatment aneurysmal rebleeding

OBJECTIVE

Initiation of external CSF drainage has been associated with a significant increase in rebleeding probability after aneurysmal subarachnoid hemorrhage (aSAH). However, the implications for acute management are uncertain. The purpose of this study was to evaluate the role of the amount of drained CSF on aneurysmal rebleeding.

METHODS

Consecutive patients with aSAH were analyzed retrospectively. Radiologically confirmed cases of aneurysmal in-hospital rebleeding were identified and predictor variables for rebleeding were retrieved from hospital records. Clinical predictors were identified through multivariate analysis, and logistic regression analysis was performed to ascertain the cutoff value for the rebleeding probability.

RESULTS

The study included 194 patients. Eighteen cases (9.3%) of in-hospital rebleeding could be identified. Using multivariate analysis, in-hospital rebleeding was significantly associated with initiation of CSF drainage (p = 0.001) and CSF drainage volume (63 ml [interquartile range (IQR) 55–69 ml] vs 25 ml [IQR 10–35 ml], p < 0.001). Logistic regression showed that 58 ml of CSF drainage within 6 hours results in a 50% rebleeding probability. The relative risk (RR) for rebleeding after drainage of more than 60 ml in 6 hours was 5.4 times greater compared with patients with less CSF drainage (RR 5.403, 95% CI 2.481–11.767; p < 0.001, number needed to harm = 1.687).

CONCLUSIONS

Volume of CSF drainage was highly correlated with the probability of in-hospital aneurysmal rebleeding. These findings suggest that the rebleeding probability can be affected in acute management should the placement of an external ventricular catheter be necessary. This finding necessitates meticulous control of the amount of drained CSF and the development of a definitive treatment protocol for this group of patients.

Contrast enhancement of vascular walls of intracranial high flow malformations in black blood MRI indicates high inflammatory activity

Background

There are controversies concerning the natural history of arteriovenous malformations (AVMs) in literature and it is not clear which AVMs should be treated and which should be just observed. Objective criteria beyond growth in serial MRIs or angiographies are needed. The use of black blood MRI is currently under investigation for evaluating the rupture risk of cerebral aneurysms, however its use for assessment of AVMs has yet to be evaluated. We therefore conducted a feasibility study on the application of black blood MRI (bbMRI) in AVMs to assess rupture risk.

Methods

Retrospective study of 10 patients with intracranial AVMs and 4 patients with arteriovenous fistulas who received a black blood MRI before treatment.

Results

AVM niduses (9/10) show contrast enhancement irrespective of rupture or size. All arteriovenous fistulas (4 / 4) were contrast enhancing irrespective of rupture.

Conclusion

High flow malformations are in a permanent stage of inflammation which does not seem to allow conclusions on their rupture risk at the current stage. BbMRI is a feasible method of identifying inflammation in AVMs and arteriovenous fistulas. However, future prospective studies are needed to evaluate whether bbMRI contrast enhancement correlates with rupture risk.

Cavernous brain malformations and their relation to black blood MRI in respect to vessel wall contrast enhancement

Background

Inflammatory responses are implicated as crucial patho-mechanisms of vascular brain malformations. Inflammation is suggested to be a key contributor to aneurysm rupture; however it is unclear whether inflammation contributes similarly to bleeding of cerebral cavernous malformations (CCMs). Black blood MRI is a sequence which identifies inflammation in blood vessel walls and in the present study is used to detect inflammatory response in CCMs.

Methods

Fifteen patients with 17 CCMs treated in our department in 2017 were retrospectively analysed. All patients received black blood MRIs and the results were analysed in correlation with, size and bleeding of CCMs.

Results

Size and bleeding status of CCMs did not correlate with contrast enhancement in the CCM wall. One of 3 patients with bleeding displayed contrast enhancement in black blood MRI, whereas the others had non enhancing lesions. Because of the small number of cases a statistical analysis was not performed.

Conclusion

In this limited cohort, inflammatory reactions in CCMs could not be detected by black blood MRI suggesting that the level of inflammation is minimal in these lesions and those different patho-mechanisms play a more important role in the rupture of CCMs.

Aneurysm treatment response prediction in follow up black blood magnetic resonance imaging. A case series study

Black blood magnetic resonance imaging (MRI)is a promising imaging tool in predicting aneurysm rupture. Could it be also valuable in evaluating the treatment effect of endovascular and conservative treated aneurysms? Two patients were treated with stent and coil and one with Aspirine (ASS). Correlation of treatment response and contrast enhancement of the aneurysm wall is examined. In the first case stenting failed to treat the aneurysm and contrast enhancement in the wall did never subside during follow up black blood MRI. In the second case the aneurysm responded well to stenting and decreased in size, which was correlating significantly with attenuation of contrast enhancement in black blood MRI. In the third case the aneurysm responded to ASS treatment by decreasing in size as shown in follow up MR-angiography and the contrast enhancement in its wall decreased after 8 months of therapy. Black blood MRI seems to be a promising tool not only in predicting aneurysms at risk of rupture, but also in observing treatment responses after endovascular procedures or even Aspirine administration. When contrast enhancement decreases, aneurysm treatment seems to be successful as can be shown in decreasing size in the follow up angiography.

Various shades of red-a systematic analysis of qualitative estimation of ALA-derived fluorescence in neurosurgery

5-Aminolevulinic acid (5-ALA)-fluorescence-guided resection is well established in many neuro-oncologic centers. Different classifications of 5-ALA-induced fluorescence have been reported. The aim of the systematic analysis was to evaluate the frequency of graduations, definitions, and designations of 5-ALA-induced fluorescence qualities. A systematic database search of PubMed was performed to identify studies reporting (1) on 5-ALA fluorescence-guided either spinal or cranial surgery, (2) on qualitative estimation and/or categorization of 5-ALA-induced fluorescence, (3) in English, and (4) were published as peer-reviewed original studies. Totally, 93 studies were identified. Different classification systems of 5-ALA-induced fluorescence were found. Over 60 % of the included studies used a dichotomized categorization of 5-ALA-induced fluorescence and 27.5 % of studies distinguished two different intensities of 5-ALA fluorescent tissue in addition to non-fluorescing tissue. More than 50 % of studies explicitly defined criteria for categorization of 5-ALA-induced fluorescence. The major limitation of the present analysis might be that it mainly comprises data from retrospective, uncontrolled, non-randomized trials. However, a precise definition of each 5-ALA-induced fluorescence quality is essential. Although dichotomized classification is the most common and simple graduation system, it may not be suitable for every clinical or scientific task. A three-level 5-ALA-induced fluorescence classification with precise definition of each fluorescence quality and their correlation with histological features would be more useful and reproducible in these cases.

5-Aminolevulinic acid-based photodynamic therapy of chordoma: In vitro experiments on a human tumor cell line

BACKGROUND

Chordomas are very rare tumors of the skull base and the sacrum. They show infiltrating and destructive growth and are known to be chemo- and radio-resistant. After surgical resection, the recurrence rate is high and overall survival limited. As current adjuvant treatments are ineffective, new treatment concepts are urgently needed. 5-aminolevulinic acid-based photodynamic therapy (5-ALA based PDT) showed promising results for malignant gliomas. However, it is unknown so far, whether chordomas accumulate protoporphyrin IX (PPIX) after application of 5-ALA and whether they are sensitive to subsequent 5-ALA based PDT.

METHODS

The immortalized human chordoma cells U-CH2 were used as in vitro model. After incubation for 4h or 6h with different 5-ALA concentrations, PPIX accumulation was determined by flow cytometry. To assess sensitivity to PDT, chordoma cells were incubated at 30.000cells/well (high cell density) or 15.000cells/well (low cell density) with graded doses of 5-ALA (0-50μg/ml) in 96-well plates and subsequently exposed to laser light of 635nm wavelength (18.75J/cm2). Cell survival was measured 24h after exposure to laser light using the WST-1 assay.

RESULTS

U-CH2 cells dose-dependently accumulated PPIX (ANOVA; p<0.0001). PPIX fluorescence was significantly higher, when cells were incubated with 5-ALA for 6h compared to 4h at higher 5-ALA concentrations (ANOVA/Bonferroni; p≤0.05 for≥30μg/ml 5-ALA). For both cell densities, a 5-ALA dose-dependent decline in viability was observed (ANOVA; p<0.0001). Viability was significantly lower at higher 5-ALA concentrations, when 30.000 cells/wells were treated compared to 15.000cells/well (ANOVA/Bonferroni; p≤0.001 for≥30μg/ml 5-ALA). LD50 was 30.25μg/ml 5-ALA.

CONCLUSION

The human UCH-2 cell line was a very useful in vitro model to study different effects of 5-ALA based PDT. For the first time, it could be shown that human chordoma cells may be destroyed by 5-ALA/PDT.

Predictive anatomical factors for rupture in middle cerebral artery mirror bifurcation aneurysms

OBJECTIVE The aim of this study was to define predictive factors for rupture of middle cerebral artery (MCA) mirror bifurcation aneurysms. METHODS The authors retrospectively analyzed the data in patients with ruptured MCA bifurcation aneurysms with simultaneous presence of an unruptured MCA bifurcation mirror aneurysm treated in two neurosurgical centers. The following parameters were measured and analyzed with the statistical software R: neck, dome, and width of both MCA aneurysms-including neck/dome and width/neck ratios, shape of the aneurysms (regular vs irregular), inflow angle of both MCA aneurysms, and the diameters of the bilateral A₁ and M₁ segments and the frontal and temporal M₂ trunks, as well as the bilateral diameter of the internal carotid artery (ICA). RESULTS The authors analyzed the data of 44 patients (15 male and 29 female, mean age 50.1 years). Starting from the usual significance level of 0.05, the Sidak-corrected significance level is 0.0039. The diameter of the measured vessels was statistically not significant, nor was the inflow angle. The size of the dome was highly significant (p = 0.0000069). The size of the neck (p = 0.0047940) and the width of the aneurysms (p = 0.0056902) were slightly nonsignificant at the stated significance level of 0.0039. The shape of the aneurysms was bilaterally identical in 22 cases (50%). In cases of asymmetrical presentation of the aneurysm shape, 19 (86.4%) ruptured aneurysms were irregular and 3 (13.6%) had a regular shape (p = 0.001). CONCLUSIONS In this study the authors show that the extraaneurysmal flow dynamics in mirror aneurysms are nonsignificant, and the aneurysmal geometry also does not seem to play a role as a predictor for rupture. The only predictors for rupture were size and shape of the aneurysms. It seems as though under the same conditions, one of the two aneurysms suffers changes in its wall and starts growing in a more or less stochastic manner. Newer imaging methods should enable practitioners to see which aneurysm has an unstable wall, to predict the rupture risk. At the moment one can only conclude that in cases of MCA mirror aneurysms the larger one, with or without shape irregularities, is the unstable aneurysm and that this is the one that needs to be treated.

A New Imaging Tool for Realtime Measurement of Flow Velocity in Intracranial Aneurysms

With modern imaging modalities of the brain a significant number of unruptured aneurysms are detected. However, not every aneurysm is prone to rupture. Because treatment morbidity is about 10% it is crucial to identify unstable aneurysms for which treatment should be discussed. Recently, new imaging tools allow analysis of flow dynamics and wall stability have become available. It seems that they might provide additional data for better risk profiling. In this study we present a new imaging tool for analysis of flow dynamics, which calculates fluid velocity in an aneurysm (Phillips Electronics, N.V.). It may identify regions with high flow and calculate flow reduction after stenting of aneurysms. Contrast is injected with a stable injection speed of 2 mL/sec for 3 sec. Two clinical cases are illustrated. Velocity in aneurysms and areas of instability can be identified and calculated during angiography in real-time. After stenting and flow diverter deployment flow reduction in the internal carotid aneurysm was reduced by 60% and there was a reduction of about 65% in the posterior cerebral artery in the second case we are reporting. The dynamic flow software calculates the flow profile in the aneurysm immediately after contrast injection. It is a real-time, patient specific tool taking into account systole, diastole and flexibility of the vasculature. These factors are an improvement as compared to current models of computational flow dynamics. We think it is a highly efficient, user friendly tool. Further clinical studies are on their way.

Level of Headaches After Surgical Aneurysm Clipping Decreases Significantly Faster Compared to Endovascular Coiled Patients

In incidental aneurysms, endovascular treatment can lead to post-procedural headaches. We studied the difference of surgical clipping vs. endovascular coiling in concern to post-procedural headaches in patients with ruptured aneurysms. Sixty-seven patients with aneurysmal subarachnoidal haemorrhage were treated in our department from September 1^st 2015 - September 1^st 2016. 43 Patients were included in the study and the rest was excluded because of late recovery or high-grade subarachnoid bleedings. Twenty-two were surgical treated and twenty-one were interventionally treated. We compared the post-procedural headaches at the time points of 24 h, 21 days, and 3 months after treatment using the visual analog scale (VAS) for pain. After surgical clipping the headache score decreased for 8.8 points in the VAS, whereas the endovascular treated population showed a decrease of headaches of 3.3 points. This difference was highly statistical significant and remained significant even after 3 weeks where the pain score for the surgically treated patients was 0.68 and for the endovascular treated 1.8. After 3 months the pain was less than 1 for both groups with surgically treated patients scoring 0.1 and endovascular treated patients 0.9 (not significant). Clipping is relieving the headaches of patients with aneurysm rupture faster and more effective than endovascular coiling. This effect stays significant for at least 3 weeks and plays a crucial role in stress relieve during the acute and subacute ICU care of such patients.

An introduction to the pathophysiology of aneurysmal subarachnoid hemorrhage

Pathophysiological processes following subarachnoid hemorrhage (SAH) present survivors of the initial bleeding with a high risk of morbidity and mortality during the course of the disease. As angiographic vasospasm is strongly associated with delayed cerebral ischemia (DCI) and clinical outcome, clinical trials in the last few decades focused on prevention of these angiographic spasms. Despite all efforts, no new pharmacological agents have shown to improve patient outcome. As such, it has become clear that our understanding of the pathophysiology of SAH is incomplete and we need to reevaluate our concepts on the complex pathophysiological process following SAH. Angiographic vasospasm is probably important. However, a unifying theory for the pathophysiological changes following SAH has yet not been described. Some of these changes may be causally connected or present themselves as an epiphenomenon of an associated process. A causal connection between DCI and early brain injury (EBI) would mean that future therapies should address EBI more specifically. If the mechanisms following SAH display no causal pathophysiological connection but are rather evoked by the subarachnoid blood and its degradation production, multiple treatment strategies addressing the different pathophysiological mechanisms are required. The discrepancy between experimental and clinical SAH could be one reason for unsuccessful translational results.

Demographic distribution of hospital admissions for brain arteriovenous malformations in Germany--estimation of the natural course with the big-data approach

BACKGROUND

Estimation of the natural history of arteriovenous malformations based on short-term observation is potentially biased by multiple factors. Retrieval of demographic information of all AVM patients of national data pools and comparison with the national demographic profile might be another way to approach the natural history.

MATERIALS AND METHODS

Upon request, the German Federal Statistical Office provided the numbers of patients admitted in Germany from 2009 through 2013 with ICD Q28.2 (brain AVM) as primary discharge diagnosis, and the corresponding age distribution. Age-related admission rates of AVM were calculated by comparison with the German demographic distribution.

RESULTS

A total of 6527 patients were hospitalized from 2009-2013 with brain AVM (Q28.2) as the principal diagnosis. Age-specific admission rate during the first year of life was high with 19.0/100,000 during the 5-year study period, corresponding to a yearly admission rate of 3.8 per 100,000 babies. Apart from the high admission rate during the first year of life, the admission rate was low, but steadily increasing during first decades of life reaching a plateau with 11.1/100,000 in the age group 30-34 years, corresponding to an annual admission rate of 2.2/100,000. After the age of 30-34 years, admission rates decreased continuously, reaching 0 in the age group 90-95 years. The lifetime risk of admission in terms of admission per 100,000 age-matched people was calculated by retrograde integration of the admission rates. At the age of 1 year, the cumulative number of future admissions for AVM during lifetime amounted to 131.3/100,000 children. For the older age groups, the chance of future admission for AVM decreased as expected, reaching 43.8/100,000 by the age of 50 and 0 by the age of 90.

CONCLUSIONS

Despite some open issues, the current data suggests that achieving old age with an untreated brain AVM is unlikely. Furthermore, the data support the concept that most brain AVMs are not necessarily a congenital entity but develop during the first decades of life.

Training for brain tumour resection: a realistic model with easy accessibility

BACKGROUND

Resection of intrinsic and extrinsic brain tumours requires an understanding of sulcal and gyral anatomy, familiarity with tissue consistency and tissue manipulation. As yet, these skills are acquired by observation and supervised manipulation during surgery, thus accepting a potential learning curve at the expense of the patient in a live surgical situation. A brain tumour model could ensure optimised manual skills and understanding of surgical anatomy acquired in an elective and relaxed teaching situation. We report and evaluate a brain tumour model, regarding availability, realistic representation of sulcal and gyral anatomy and tissue consistency.

METHOD

Freshly prepared agar-agar solution with different concentrations was added with highlighter ink and injected into fresh sheep brains.

RESULTS

Hardened agar-agar solution formed masses comparable to malignant brain tumours. Variation of the agar-agar concentration influenced diffusion of agar-agar solution in the adjacent brain tissue. Higher concentrated agar-agar solutions formed sharply delimitated masses mimicking cerebral metastases and lower concentrated agar-agar solutions tended to diffuse into the adjacent cerebral tissue. Adding highlighter ink to the agar-agar solution produced fluorescence after blue light excitation comparable to the 5-ALA induced fluorescence of malignant glioma.

CONCLUSIONS

The described in vitro sheep brain tumour model is simple and realistic, available practically everywhere and cheap. Therefore, it could be useful for young neurosurgical residents to acquire basic neuro-oncological skills, experiencing properties of the cerebral brain texture and its haptic perception and to learn handling of neurosurgical equipment.

Chordomas of the skull base and cervical spine: clinical outcomes associated with a multimodal surgical resection combined with proton-beam radiation in 40 patients

Previous studies of chordoma have focused on either surgery, radiotherapy, or particular tumor locations. This paper reviewed the outcomes of surgery and proton radiotherapy with various tumor locations. Between 2001 and 2008, 40 patients with chordomas of the skull base and cervical spine had surgery at our hospital. Most patients received proton therapy. Their clinical course was reviewed. Age, sex, tumor location, timing of surgery, extent of resection, and chondroid appearance were evaluated in regard to the progression-free survival (PFS) and overall survival (OS). The primary surgery (PS) group was analyzed independently. The extensive resection rate was 42.5%. Permanent neurological morbidity was seen in 3.8%. Radiotherapy was performed in 75% and the mean dose was 68.9 cobalt gray equivalents. The median follow-up was 56.5 months. The 5-year PFS and OS rates were 70% and 83.4%, respectively. Metastasis was seen in 12.5%. The tumor location at the cranio-cervical junction (CCJ) was associated with a lower PFS (P = 0.007). In the PS group, a younger age and the CCJ location were related to a lower PFS (P = 0.008 and P < 0.001, respectively). The CCJ location was also related to a lower OS (P = 0.043) and it was more common in young patients (P = 0.002). Among the survivors, the median of the last Karnofsky Performance Scale score was 80 with 25.7% of patients experiencing an increase and 11.4% experiencing a decrease. Multimodal surgery and proton therapy thus improved the chordoma treatment. The CCJ location and a younger age are risks for disease progression.

ANTEROLATERAL APPROACH WITHOUT FIXATION FOR RESECTION OF AN INTRADURAL SCHWANNOMA OF THE CERVICAL SPINAL CANAL

OBJECTIVE

Although an anterolateral approach is an ideal approach to the anterior part of the cervical spinal canal, it is not often used because of various technical difficulties. This article presents the case of a patient with an intradural schwannoma ventrolateral to the spinal cord and describes the technique, anterolateral surgery without fixation, that was used to remove it.

CASE PRESENTATION

A 71-year-old man presented with neck pain and easy fatigability of the legs. Magnetic resonance imaging showed an intradural tumor ventrolateral to the spinal cord at the C3 level. The diagnosis was a schwannoma.

TECHNIQUE

A right anterolateral approach was selected for the resection. In the dissection between the sternocleidomastoid muscle and the internal jugular vein, the accessory nerve was retracted with the fat tissue. At C3, the prevertebral aponeurosis was laterally retracted to protect the sympathetic chain. The C3 transverse process was rongeured, and the vertebral artery was shifted laterally with the venous plexus. The C2–C3 uncovertebral joint and the right third of the C3 body were removed (partial corpectomy). The tumor was easily found in the dural sac and was totally removed. The surgical wound was closed in a watertight fashion. No fixation was necessary. The symptoms improved after the operation.

DISCUSSION

The anterolateral approach is one of the best approaches for resecting ventrally located intradural lesions because it allows minimally invasive surgery. Control and protection of the accessory nerve, sympathetic chain, and vertebral artery are the keys to success.

Oxygen-conserving reflexes of the brain: the current molecular knowledge

The trigemino-cardiac reflex (TCR) may be classified as a sub-phenomenon in the group of the so-called 'oxygen-conserving reflexes'. Within seconds after the initiation of such a reflex, there is neither a powerful and differentiated activation of the sympathetic system with subsequent elevation in regional cerebral blood flow (CBF) with no changes in the cerebral metabolic rate of oxygen (CMRO(2)) or in the cerebral metabolic rate of glucose (CMRglc). Such an increase in regional CBF without a change of CMRO(2) or CMRglc provides the brain with oxygen rapidly and efficiently and gives substantial evidence that the TCR is an oxygen-conserving reflex. This system, which mediates reflex protection projects via currently undefined pathways from the rostral ventrolateral medulla oblongata to the upper brainstem and/or thalamus which finally engage a small population of neurons in the cortex. This cortical centre appears to be dedicated to reflexively transduce a neuronal signal into cerebral vasodilatation and synchronization of electrocortical activity. Sympathetic excitation is mediated by cortical-spinal projection to spinal pre-ganglionic sympathetic neurons whereas bradycardia is mediated via projections to cardiovagal motor medullary neurons. The integrated reflex response serves to redistribute blood from viscera to brain in response to a challenge to cerebral metabolism, but seems also to initiate a preconditioning mechanism. Better and more detailed knowledge of the cascades, transmitters and molecules engaged in such endogenous (neuro) protection may provide new insights into novel therapeutic options for a range of disorders characterized by neuronal death and into cortical organization of the brain.