Laser speckle contrast imaging versus microvascular Doppler sonography in aneurysm surgery: A prospective study.

Objective: This study aimed to compare microvascular Doppler sonography (MDS) and laser speckle contrast imaging (LSCI) for assessing vessel patency and aneurysm occlusion during microsurgical clipping of intracranial aneurysms. Methods: MDS and LSCI were used after clip placement during six neurovascular procedures including six patients, and agreement between the two techniques was assessed. LSCI was performed in parallel or right after MDS evaluation. The Doppler response was assessed through listening while flow in the LSCI videos was evaluated by three blinded neurovascular surgeons after the surgery. Statistical analysis determined the agreement between the techniques in assessing flow in 18 regions of interest (ROIs). Results: Agreement between MDS and LSCI in assessing vessel patency was observed in 87 % of the ROIs. LSCI accurately identified flow in 93.3 % of assessable ROIs, with no false positive or negative measurements. Three ROIs were not assessable with LSCI due to motion artifacts or poor image quality. No complications were observed. Conclusions: LSCI demonstrated high agreement with MDS in assessing vessel patency during microsurgical clipping of intracranial aneurysms. It provided continuous, real-time, full-field imaging with high spatial resolution and temporal resolution. While MDS allowed evaluation of deep vascular regions, LSCI complemented it by offering unlimited assessment of surrounding vessels.

Utility of the LACE index to assess risk of mortality and readmission in patients with spinal infections.

Retrospective cohort study. To assess the utility of the LACE index for predicting death and readmission in patients with spinal infections (SI). SIs are severe conditions, and their incidence has increased in recent years. The LACE (Length of stay, Acuity of admission, Comorbidities, Emergency department visits) index quantifies the risk of mortality or unplanned readmission. It has not yet been validated for SIs. LACE indices were calculated for all adult patients who underwent surgery for spinal infection between 2012 and 2021. Data were collected from a single academic teaching hospital. Outcome measures included the LACE index, mortality, and readmission rate within 30 and 90 days. In total, 164 patients were analyzed. Mean age was 64.6 (± 15.1) years, 73 (45%) were female. Ten (6.1%) patients died within 30 days and 16 (9.8%) died within 90 days after discharge. Mean LACE indices were 13.4 (± 3.6) and 13.8 (± 3.0) for the deceased patients, compared to 11.0 (± 2.8) and 10.8 (± 2.8) for surviving patients (p = 0.01, p < 0.001), respectively. Thirty-seven (22.6%) patients were readmitted ≤ 30 days and 48 (29.3%) were readmitted ≤ 90 days. Readmitted patients had a significantly higher mean LACE index compared to non-readmitted patients (12.9 ± 2.1 vs. 10.6 ± 2.9, < 0.001 and 12.8 ± 2.3 vs. 10.4 ± 2.8, p < 0.001, respectively). ROC analysis for either death or readmission within 30 days estimated a cut-off LACE index of 12.0 points (area under the curve [AUC] 95% CI, 0.757 [0.681-0.833]) with a sensitivity of 70% and specificity of 69%. Patients with SI had high LACE indices that were associated with high mortality and readmission rates. The LACE index can be applied to this patient population to predict the risk of early death or unplanned readmission.

Quality of life in patients with unruptured intracranial aneurysms treated conservatively, before and after occlusion. A single center cohort study.

Introduction: Rupture of intracranial aneurysms is the most frequent cause of subarachnoid hemorrhage and is associated with high morbidity. Recommendations for preventive treatment of unruptured aneurysms (UIAs) remain controversial due to inconsistent data on their natural history and the risks associated with treatment. The awareness of being diagnosed with one or more UIAs can provoke feelings of anxiety and psychosocial distress. Therefore, the impact of management on a patients' health perception and quality of life (QoL) is an essential factor to be considered in the treatment decision-making process. Objective: The aim of this study was to assess and compare QoL in patients diagnosed with one or more UIAs depending on their treatment as well as their pre- or postoperative status. Material and methods: Demographic and clinical data as well as results of the 15D quality of life (15D QoL) questionnaire of 189 patients were prospectively collected and retrospectively analyzed. Patients were categorized into different subgroups, depending on their treatment modalities (conservative, microsurgery or endovascular treatment) and their pre- or postoperative status at the time of completion of the questionnaire. Statistical analysis was performed to compare the different subgroups. Results: Conservatively treated patients had similar mean 15D QoL scores as preoperative patients. Despite an initial postoperative QoL reduction and a trend towards recovery and even an improvement of QoL in the long term after UIA occlusion, neither clinically relevant nor statistically significant differences between preoperative and postoperative mean 15D QoL scores were observed. Conclusions: Health-related QoL does not significantly change after treatment of UIAs when compared to the preoperative period. Further studies are needed to confirm long-term postoperative quality of life changes as well as treatment-related influencing factors on patients' quality of life.

Cortico-cortical evoked potentials of language tracts in minimally invasive glioma surgery guided by Penfield stimulation.

OBJECTIVE: We investigated the feasibility of recording cortico-cortical evoked potentials (CCEPs) in patients with low- and high-grade glioma. We compared CCEPs during awake and asleep surgery, as well as those stimulated from the functional Broca area and recorded from the functional Wernicke area (BtW), and vice versa (WtB). We also analyzed CCEP properties according to tumor location, histopathology, and aphasia. METHODS: We included 20 patients who underwent minimally invasive surgery in an asleep-awake-asleep setting. Strip electrode placement was guided by classical Penfield stimulation of positive language sites and fiber tracking of the arcuate fascicle. CCEPs were elicited with alternating monophasic single pulses of 1.1 Hz frequency and recorded as averaged signals. Intraoperatively, there was no post-processing of the signal. RESULTS: Ninety-seven CCEPs from 19 patients were analyzed. There was no significant difference in CCEP properties when comparing awake versus asleep, nor BtW versus WtB. CCEP amplitude and latency were affected by tumor location and histopathology. CCEP features after tumor resection correlated with short- and long-term postoperative aphasia. CONCLUSION: CCEP recordings are feasible during minimally invasive surgery. CCEPs might be surrogate markers for altered connectivity of the language tracts. SIGNIFICANCE: This study may guide the incorporation of CCEPs into intraoperative neurophysiological monitoring.

Swiss trial of decompressive craniectomy versus best medical treatment of spontaneous supratentorial intracerebral haemorrhage (SWITCH): an international, multicentre, randomised-controlled, two-arm, assessor-blinded trial.

RATIONALE: Decompressive craniectomy (DC) is beneficial in people with malignant middle cerebral artery infarction. Whether DC improves outcome in spontaneous intracerebral haemorrhage (ICH) is unknown. AIM: To determine whether DC without haematoma evacuation plus best medical treatment (BMT) in people with ICH decreases the risk of death or dependence at 6 months compared to BMT alone. METHODS AND DESIGN: SWITCH is an international, multicentre, randomised (1:1), two-arm, open-label, assessor-blinded trial. Key inclusion criteria are age ⩽75 years, stroke due to basal ganglia or thalamic ICH that may extend into cerebral lobes, ventricles or subarachnoid space, Glasgow coma scale of 8-13, NIHSS score of 10-30 and ICH volume of 30-100 mL. Randomisation must be performed <66 h after onset and DC <6 h after randomisation. Both groups will receive BMT. Participants randomised to the treatment group will receive DC of at least 12 cm in diameter according to institutional standards. SAMPLE SIZE: A sample of 300 participants randomised 1:1 to DC plus BMT versus BMT alone provides over 85% power at a two-sided alpha-level of 0.05 to detect a relative risk reduction of 33% using a chi-squared test. OUTCOMES: The primary outcome is the composite of death or dependence, defined as modified Rankin scale score 5-6 at 6 months. Secondary outcomes include death, functional status, quality of life and complications at 180 days and 12 months. DISCUSSION: SWITCH will inform physicians about the outcomes of DC plus BMT in people with spontaneous deep ICH, compared to BMT alone. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT02258919.

Applied deep learning in neurosurgery: identifying cerebrospinal fluid (CSF) shunt systems in hydrocephalus patients.

BACKGROUND: Over the recent decades, the number of different manufacturers and models of cerebrospinal fluid shunt valves constantly increased. Proper identification of shunt valves on X-ray images is crucial to neurosurgeons and radiologists to derive further details of a specific shunt valve, such as opening pressure settings and MR scanning conditions. The main aim of this study is to evaluate the feasibility of an AI-assisted shunt valve detection system. METHODS: The dataset used contains 2070 anonymized images of ten different, commonly used shunt valve types. All images were acquired from skull X-rays or scout CT-images. The images were randomly split into a 80% training and 20% validation set. An implementation in Python with the FastAi library was used to train a convolutional neural network (CNN) using a transfer learning method on a pre-trained model. RESULTS: Overall, our model achieved an F1-score of 99% to predict the correct shunt valve model. F1-scores for individual shunt valves ranged from 92% for the Sophysa Sophy Mini SM8 to 100% for several other models. CONCLUSION: This technology has the potential to automatically detect different shunt valve models in a fast and precise way and may facilitate the identification of an unknown shunt valve on X-ray or CT scout images. The deep learning model we developed could be integrated into PACS systems or standalone mobile applications to enhance clinical workflows.

Intraoperative Neurophysiologic Monitoring and Mapping During Surgery on Intramedullary Spinal Cord Tumors in Children and Adolescents.

SUMMARY: Surgical resection of intramedullary spinal cord tumors carries significant risks of neurologic deficits, especially in cases of infiltrative tumors. In pediatric patients, this type of surgery may be associated with a high risk of poor neurologic outcome. Intraoperative neurophysiologic monitoring has been adopted as part of the clinical routine by many centers as a useful adjunct for intraoperative assessment of neurologic integrity. To what extent intraoperative neurophysiologic mapping strategies may further support intraoperative decision-making is still a matter of debate. Here, we report on a small cohort of five pediatric patients in whom mapping with the double-train paradigm was used to identify the dorsal column and corticospinal tract and to guide the surgical resection. We also discuss the possible benefits and challenges regarding the available literature.

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

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

Cortical perfusion measurements with laser speckle contrast imaging during adenosine induced cardiac arrest for aneurysm clipping: a case report.

Adenosine induced cardiac arrest (AiCA) is one of the methods used to facilitate microsurgical aneurysm clipping by providing more visibility and less pressure in the aneurysmal sac and neighboring vessels. We report the use of laser speckle contrast imaging (LSCI) during AiCA to monitor the changes in pulsation and perfusion on the cortical surface during adenosine induced cardiac arrest for aneurysm clipping surgery. Application of this technology for perfusion monitoring may improve workflow and surgical guidance and provide valuable feedback continuously throughout the procedure. ClinicalTrials.gov identifier: NCT0502840.

Diagnosis of Small Unruptured Intracranial Aneurysms : Comparison of 7 T versus 3 T MRI.

PURPOSE: Differentiating normal anatomical variants such as an infundibulum or a vascular loop from true intracranial aneurysms is crucial for patient management. We hypothesize that high-resolution 7 T magnetic resonance imaging (MRI) improves the detection and characterization of normal anatomical variants that may otherwise be misdiagnosed as small unruptured aneurysms. METHODS: This is a retrospective, single-center study. All patients were scanned on a clinically approved 7 T MRI scanner and on a 3 T scanner. Image analysis was performed independently by three neuroradiologists blinded to clinical information. The presence of an unruptured intracranial aneurysm (UIA) and level of diagnostic certainty were assessed and the interrater agreement was calculated. If an aneurysm was present, the anatomic location and shape were recorded and compared. RESULTS: In total, 53 patients with equivocal cerebrovascular findings on 1.5 T or 3 T MRI referred for a 7T MRI examination were included. Aneurysms were suspected in 42 patients examined at 3 T and in 23 patients at 7 T (rate difference 36%, 95% confidence interval, CI, 19-53%, p-value < 0.001). Major disagreement between the field strengths was observed in the A1 segment of anterior cerebral artery/anterior communicating artery (A1/ACOM) complex. The interrater agreement among the readers on the presence of an aneurysm on 7 T MRI was higher than that for 3 T MRI (0.925, 95% CI 0.866-0.983 vs. 0.786, 95% CI 0.700-0.873). CONCLUSION: Our analysis demonstrates a significantly higher interrater agreement and improved diagnostic certainty when small intracranial aneurysms are visualized on 7 T MRI compared to 3 T. In a selected patient cohort, clinical implementation of 7 T MRI may help to establish the definitive diagnosis and thus have a beneficial impact on patient management.

Intracranial Aneurysm "Clip Anchoring": Technical Note.

Clip slippage and displacement during or after intracranial aneurysm surgery is associated with morbidity and can be detrimental. We report the usage of concomitant aneurysm clips and artery clips aiming to avoid this complication in a patient undergoing elective aneurysm surgical clipping.

Surgical closure of spinal cerebrospinal fluid leaks improves symptoms in patients with superficial siderosis.

BACKGROUND AND PURPOSE: Spinal cerebrospinal fluid (CSF) leaks may cause a myriad of symptoms, most common being orthostatic headache. In addition, ventral spinal CSF leaks are a possible etiology of superficial siderosis (SS), a rare condition characterized by hemosiderin deposits in the central nervous system (CNS). The classical presentation of SS involves ataxia, bilateral hearing loss, and myelopathy. Unfortunately, treatment options are scarce. This study was undertaken to evaluate whether microsurgical closure of CSF leaks can prevent further clinical deterioration or improve symptoms of SS. METHODS: This cohort study was conducted using data from a prospectively maintained database in two large spontaneous intracranial hypotension (SIH) referral centers in Germany and Switzerland of patients who meet the modified International Classification of Headache Disorders, 3rd edition criteria for SIH. Patients with spinal CSF leaks were screened for the presence of idiopathic infratentorial symmetric SS of the CNS. RESULTS: Twelve patients were included. The median latency between the onset of orthostatic headaches and symptoms attributed to SS was 9.5 years. After surgical closure of the underlying spinal CSF leak, symptoms attributed to SS improved in seven patients and remained stable in three. Patients who presented within 1 year after the onset of SS symptoms improved, but those who presented in 8-12 years did not improve. We could show a significant association between patients with spinal longitudinal extrathecal collections and SS. CONCLUSIONS: Long-standing untreated ventral spinal CSF leaks can lead to SS of the CNS, and microsurgical sealing of spinal CSF leaks might stop progression and improve symptoms in patients with SS in a time-dependent manner.

Surgical Outcome of Patients With Supratentorial Meningiomas Aged 80 Years or Older-Retrospective International Multicenter Study.

BACKGROUND AND OBJECTIVES: Demographic changes will lead to an increase in old patients, a population with significant risk of postoperative morbidity and mortality, requiring neurosurgery for meningiomas. This multicenter study aims to report neurofunctional status after resection of patients with supratentorial meningioma aged 80 years or older, to identify factors associated with outcome, and to validate a previously proposed decision support tool. METHODS: Neurofunctional status was assessed by the Karnofsky Performance Scale (KPS). Patients were categorized in poor (KPS ≤40), intermediate (KPS 50-70), and good (KPS ≥80) preoperative subgroups. Volumetric analyses of tumor and peritumoral brain edema (PTBE) were performed; volumes were scored as small (<10 cm 3 ), medium (10-50 cm 3 ), and large (>50 cm 3 ). RESULTS: The study population consisted of 262 patients, and the median age at surgery was 83.0 years. The median preoperative KPS was 70; 117 (44.7%) patients were allotted to the good, 113 (43.1%) to the intermediate, and 32 (12.2%) to the poor subgroup. The median tumor and PTBE volumes were 30.2 cm 3 and 27.3 cm 3 ; large PTBE volume correlated with poor preoperative KPS status ( P = .008). The 90-day and 1-year mortality rates were 9.0% and 13.2%, respectively. Within the first postoperative year, 101 (38.5%) patients improved, 87 (33.2%) were unchanged, and 74 (28.2%) were functionally worse (including deaths). Each year increase of age associated with 44% (23%-70%) increased risk of 90-day and 1-year mortality. In total, 111 (42.4%) patients suffered from surgery-associated complications. Maximum tumor diameter ≥5 cm (odds ratio 1.87 [1.12-3.13]) and large tumor volume (odds ratio 2.35 [1.01-5.50]) associated with increased risk of complications. Among patients with poor preoperative status and large PTBE, most (58.3%) benefited from surgery. CONCLUSION: Patients with poor preoperative neurofunctional status and large PTBE most often showed postoperative improvements. The decision support tool may be of help in identifying cases that most likely benefit from surgery.

Intraoperative in vivo confocal laser endomicroscopy imaging at glioma margins: can we detect tumor infiltration?

OBJECTIVE: Confocal laser endomicroscopy (CLE) is a US Food and Drug Administration-cleared intraoperative real-time fluorescence-based cellular resolution imaging technology that has been shown to image brain tumor histoarchitecture rapidly in vivo during neuro-oncological surgical procedures. An important goal for successful intraoperative implementation is in vivo use at the margins of infiltrating gliomas. However, CLE use at glioma margins has not been well studied. METHODS: Matching in vivo CLE images and tissue biopsies acquired at glioma margin regions of interest (ROIs) were collected from 2 institutions. All images were reviewed by 4 neuropathologists experienced in CLE. A scoring system based on the pathological features was implemented to score CLE and H&E images from each ROI on a scale from 0 to 5. Based on the H&E scores, all ROIs were divided into a low tumor probability (LTP) group (scores 0-2) and a high tumor probability (HTP) group (scores 3-5). The concordance between CLE and H&E scores regarding tumor probability was determined. The intraclass correlation coefficient (ICC) and diagnostic performance were calculated. RESULTS: Fifty-six glioma margin ROIs were included for analysis. Interrater reliability of the scoring system was excellent when used for H&E images (ICC [95% CI] 0.91 [0.86-0.94]) and moderate when used for CLE images (ICC [95% CI] 0.69 [0.40-0.83]). The ICCs (95% CIs) of the LTP group (0.68 [0.40-0.83]) and HTP group (0.68 [0.39-0.83]) did not differ significantly. The concordance between CLE and H&E scores was 61.6%. The sensitivity and specificity values of the scoring system were 79% and 37%. The positive predictive value (PPV) and negative predictive value were 65% and 53%, respectively. Concordance, sensitivity, and PPV were greater in the HTP group than in the LTP group. Specificity was higher in the newly diagnosed group than in the recurrent group. CONCLUSIONS: CLE may detect tumor infiltration at glioma margins. However, it is not currently dependable, especially in scenarios where low probability of tumor infiltration is expected. The proposed scoring system has excellent intrinsic interrater reliability, but its interrater reliability is only moderate when used with CLE images. These results suggest that this technology requires further exploration as a method for consistent actionable intraoperative guidance with high dependability across the range of tumor margin scenarios. Specific-binding and/or tumor-specific fluorophores, a CLE image atlas, and a consensus guideline for image interpretation may help with the translational utility of CLE.

Patient-reported symptomatology and its course in spontaneous intracranial hypotension - Beware of a chameleon.

OBJECTIVE: Although orthostatic headache is the hallmark symptom of spontaneous intracranial hypotension (SIH), patients can present with a wide range of different complaints and thereby pose a diagnostic challenge for clinicians. Our aim was to describe and group the different symptoms associated with SIH and their course over time. METHODS: We retrospectively surveyed consecutive patients diagnosed and treated for SIH at our institution from January 2013 to May 2020 with a specifically designed questionnaire to find out about their symptomatology and its course. RESULTS: Of 112 eligible patients, 79 (70.5%) returned the questionnaire and were included in the analysis. Of those, 67 (84.8%) reported initial orthostatic headaches, whereas 12 (15.2%) denied having this initial symptom. All except one (98.7%) patients reported additional symptoms: most frequently cephalic pressure (69.6%), neck pain (68.4%), auditory disturbances (59.5%), nausea (57%), visual disturbances (40.5%), gait disturbance (20.3%), confusion (10.1%) or sensorimotor deficits (21.5%). Fifty-seven (72.2%) patients reported a development of the initial symptoms predominantly in the first three months after symptom onset. Age and sex were not associated with the symptomatology or its course (p > 0.1). CONCLUSION: Although characteristic of SIH, a relevant amount of patients present without orthostatic headaches. In addition, SIH can manifest with non-orthostatic headaches at disease onset or during the course of the disease. Most patients report a wide range of associated complaints. A high degree of suspicion is crucial for an early diagnosis and targeted treatment.

Dynamic Mixed-Reality Patient-Specific Aneurysm Clipping Simulation for Two Cases-A Feasibility Study.

BACKGROUND AND OBJECTIVE: Intracranial aneurysm (IA) clipping is a complex neurosurgical procedure which demands advanced technology to minimize risks and maximize patient outcomes. This study aims to evaluate the feasibility of training patient-specific microsurgical clipping procedures using a mixed-reality physical neurosurgical simulator for unruptured IA. METHODS: Two board-certified neurosurgeons were asked to simulate surgery in 2 patient-specific left-side unruptured middle cerebral artery-bifurcation IA models. The study was conducted in the operation theater under realistic conditions using a mixed-reality physical neurosurgical simulator. Time, procedural, and outcome-related information was collected. The participating neurosurgeons were encouraged to attempt all possible clipping strategies, even those deemed suboptimal, reporting the outcome of each strategy. Finally, to evaluate the feasibility and added value of integrating indocyanine green fluorescence angiography (ICG-FA) with the simulator, the ICG-FA videos for each clipping strategy were analyzed and compared with the reported clipping outcomes. RESULTS: Between 4 and 8, different clipping strategies were applied per aneurysm model; the number of strategies was higher in Patient Model 1 (6.5 ± 1.5) (more complex aneurysm) than in Patient Model 2 (5.0 ± 1.0). The clipping strategies differed between surgeons. At most, 53.5 minutes were necessary to complete each training session, but more than double the time was spent on the more complex aneurysm. Up to 53.8% (Patient Model 1) and 50% (Patient Model 2) of the attempted strategies were discarded by the neurosurgeons during the simulation. Evaluation of aneurysm occlusion through ICG-FA was specific, although sensitivity was poor. CONCLUSION: The present mixed-reality patient-specific simulator allows testing, anticipating, and discarding different aneurysm microsurgical clipping strategies regardless of the pathology complexity. Specific limitations should be considered regarding ICG-FA aneurysm inspection after clipping.

Intraoperative Laser Speckle Contrast Imaging to Assess Vessel Flow in Neurosurgery: A Pilot Study.

BACKGROUND AND OBJECTIVES: Laser speckle contrast imaging (LSCI) has emerged as a promising tool for assessment of vessel flow during neurosurgery. We aimed to investigate the feasibility of visualizing vessel flow in the macrocirculation with a new fully microscope-integrated LSCI system and assess the validity and objectivity of findings compared with fluorescence angiography (FA). METHODS: This is a single-center prospective observational study enrolling adult patients requiring microsurgical treatment for brain vascular pathologies or brain tumors. Three independent raters, blinded toward findings of FA, reviewed regions of interest (ROIs) placed in exposed vessels and target structures. The primary end point was the validity of LSCI for assessment of vessel flow as measured by the agreement with FA. The secondary end point was objectivity, measured as the inter-rater agreement of LSCI findings. RESULTS: During 18 surgical procedures, 23 observations using FA and LSCI were captured simultaneously. Using LSCI, vessel flow was assessable in 62 (86.1%) and not assessable in 10 (13.9%) ROIs. The agreement between LSCI and FA was 86.1%, with an agreement coefficient of 0.85 (95% CI: 0.75-0.94). Disagreement between LSCI and FA was observed in the 10 ROIs that were not assessable. The agreement between ROIs that were assessable using LSCI and FA was 100%. The inter-rater agreement of LSCI findings was 87.9%, with an agreement coefficient of 0.86 (95% CI: 0.79-0.94). CONCLUSION: Fully microscope-integrated LSCI is feasible and has a high potential for clinical utility. Because of its characteristics, LSCI can be viewed as a full-field visual micro-Doppler that can be used as a complementary method to FA for assessing vessel flow during neurosurgery. Despite technical limitations related to the early development phase of the fully microscope-integrated system, we demonstrated reasonable validity and objectivity of findings compared with FA. Further research and refinement of the system may enhance its value in neurosurgical applications.

Diagnosis and surgical therapy of spontaneous intracranial hypotension.

Spontaneous intracranial hypotension (SIH) is a serious medical condition caused by loss of cerebrospinal fluid at the level of the spine, which, when not treated, may cause substantial long-term disability and increase morbidity. The following video summarizes the necessary steps for successful diagnosis and treatment of SIH, starting with a brain and spine magnetic resonance imaging, followed by dynamic myelography. Because an epidural bloodpatch did not provide a lasting relief, the patient underwent surgery which demonstrated a ventral dural slit caused by an osteodiscogenic microspur. In the 1-month follow up, the patient was symptom free. This video is meant to raise awareness of SIH among clinicians in order to increase general sensitivity for this diagnosis.

Opportunities and challenges of supervised machine learning for the classification of motor evoked potentials according to muscles.

BACKGROUND: Even for an experienced neurophysiologist, it is challenging to look at a single graph of an unlabeled motor evoked potential (MEP) and identify the corresponding muscle. We demonstrate that supervised machine learning (ML) can successfully perform this task. METHODS: Intraoperative MEP data from supratentorial surgery on 36 patients was included for the classification task with 4 muscles: Extensor digitorum (EXT), abductor pollicis brevis (APB), tibialis anterior (TA) and abductor hallucis (AH). Three different supervised ML classifiers (random forest (RF), k-nearest neighbors (kNN) and logistic regression (LogReg)) were trained and tested on either raw or compressed data. Patient data was classified considering either all 4 muscles simultaneously, 2 muscles within the same extremity (EXT versus APB), or 2 muscles from different extremities (EXT versus TA). RESULTS: In all cases, RF classifiers performed best and kNN second best. The highest performances were achieved on raw data (4 muscles 83%, EXT versus APB 89%, EXT versus TA 97% accuracy). CONCLUSIONS: Standard ML methods show surprisingly high performance on a classification task with intraoperative MEP signals. This study illustrates the power and challenges of standard ML algorithms when handling intraoperative signals and may lead to intraoperative safety improvements.