Association of the classification of intraoperative adverse events (ClassIntra) with complications and neurological outcome after neurosurgical procedures: a prospective cohort study.

PURPOSE: To analyze the reliability of the classification of intraoperative adverse events (ClassIntra) to reflect intraoperative complications of neurosurgical procedures and the potential to predict the postoperative outcome including the neurological performance. The ClassIntra classification was recently introduced and found to be reliable for assessing intraoperative adverse events and predicting postoperative complications across different surgical disciplines. Nevertheless, its potential role for neurosurgical procedures remains elusive. METHODS: This is a prospective, monocentric cohort study assessing the ClassIntra in 422 adult patients who underwent a neurosurgical procedure and were hospitalized between July 1, 2021, to December 31, 2021. The primary outcome was the occurrence of intraoperative complications graded according to ClassIntra and the association with postoperative outcome reflected by the Clavien-Dindo classification and comprehensive complication index (CCI). The ClassIntra is defined as intraoperative adverse events as any deviation from the ideal course on a grading scale from grade 0 (no deviation) to grade V (intraoperative death) and was set at sign-out in agreement between neurosurgeon and anesthesiologist. Secondary outcomes were the neurological outcome after surgery as defined by Glasgow Coma Scale (GCS), modified Rankin scale (mRS), Neurologic Assessment in Neuro-Oncology (NANO) scale, National Institute Health of Strokes Scale (NIHSS), and Karnofsky Performance Score (KPS), and need for unscheduled brain scan. RESULTS: Of 442 patients (mean [SD] age, 56.1 [16.2]; 235 [55.7%] women and 187 [44.3%] men) who underwent a neurosurgical procedure, 169 (40.0%) patients had an intraoperative adverse event (iAE) classified as ClassIntra I or higher. The NIHSS score at admission (OR, 1.29; 95% CI, 1.03-1.63, female gender (OR, 0.44; 95% CI, 0.23-0.84), extracranial procedures (OR, 0.17; 95% CI, 0.08-0.61), and emergency cases (OR, 2.84; 95% CI, 1.53-3.78) were independent risk factors for a more severe iAE. A ClassIntra ≥ II was associated with increased odds of postoperative complications classified as Clavien-Dindo (p < 0.01), neurological deterioration at discharge (p < 0.01), prolonged hospital (p < 0.01), and ICU stay (p < 0.01). For elective craniotomies, severity of ClassIntra was associated with the CCI (p < 0.01) and need for unscheduled CT or MRI scan (p < 0.01). The proportion of a ClassIntra ≥ II was significantly higher for emergent craniotomies (56.2%) and associated with in-hospital mortality, and an unfavorable neurological outcome (p < 0.01). CONCLUSION: Findings of this study suggest that the ClassIntra is sensitive for assessing intraoperative adverse events and sufficient to identify patients with a higher risk for developing postoperative complications after a neurosurgical procedure.

Acute low-pressure hydrocephalus in aneurysmal subarachnoid hemorrhage.

OBJECTIVE: Acute and chronic hydrocephalus are common pathologies after aneurysmal subarachnoid hemorrhage (SAH). Generally, the presence of acute hydrocephalus is associated with elevated intracranial pressure (ICP) treated with a ventricular drain. Subsequently, however, pronounced hydrocephalus without elevated ICP may develop in some patients with SAH in the postacute phase. This is described as acute low-pressure hydrocephalus (aLPH), and there are very limited data in the literature of this pathology. The aim of this study was to evaluate the rate of and factors associated with aLPH and describe its clinical course. METHODS: In this retrospective single-center cohort study, the frequency and clinical characteristics of SAH-associated aLPH were investigated. Acute LPH was defined as an increase in ventricular size as measured by the Evans index, ICP within the normal range (< 5 mm Hg) at the time of ventricular enlargement, and timely neurological improvement after indwelling ventricular CSF drainage with negative pressure up to 5 cm H2O below normal level. Demographic and SAH-specific factors in patients with SAH treated using an external ventricular drain were extracted from the electronic medical chart and further analyzed. RESULTS: From November 2010 to May 2020, 15 (3.7.%) of 406 patients with SAH fulfilled the criteria for aLPH. Acute LPH was diagnosed after an average of 13.1 ± 7.7 days. The presence of IVH and its extension were associated with the occurrence of aLPH. After undergoing the transient phase of aLPH, these patients subsequently developed a chronic, typical malresorptive hydrocephalus requiring a ventriculoperitoneal shunt more often (66.7% vs 17.4%, p < 0.001) and stayed longer in the intensive care unit (27 vs 20.5 days, p = 0.043) and in the hospital (36.4 vs 26.3 days, p = 0.004). CONCLUSIONS: Acute LPH is a rare pathology in patients with SAH and negatively impacts the clinical course. It should be especially considered in patients with a lack of neurological improvement, an increase in ventricular width, and normal ICP values, so that forced CSF drainage is implemented.

Terson Syndrome in Patients with Aneurysmal Subarachnoid Hemorrhage: A 10-Year Single-Center Experience.

BACKGROUND: Terson syndrome (TS), an intraocular hemorrhage associated with aneurysmal subarachnoid hemorrhage (aSAH), occurs in up to 46% of all patients with subarachnoid hemorrhage. Despite its high incidence, TS is underrepresented in the literature, and patients with aSAH are sometimes not systematically evaluated for the presence of TS in clinical practice. This work aims to raise awareness of TS, reevaluate previous scientific findings, describe risk factors associated with the occurrence of TS, and present our local diagnostic and treatment concept. METHODS: All patients with aSAH treated at our institution between October 2010 and May 2020 were included in this retrospective study. The frequency of ophthalmological screening by indirect funduscopy, as well as the results, was investigated. In addition, the collection and statistical analysis of epidemiological and clinical data was performed using χ2, Kruskal-Wallis, and analysis of variance testing; multivariate regression; and receiver operating characteristic analysis. The significance level was set at p < 0.05. RESULTS: A total of 617 patients were treated for aSAH in our institution. Of these, 367 patients (59.5%) were ophthalmologically examined for the presence of TS. The rate of TS in the examined patients was 21.3% (n = 78). Patients with TS had significantly higher Fisher and World Federation of Neurosurgical Societies (WFNS) scores (p < 0.0001). Regression analyses showed WFNS grade (p = 0.003) and the occurrence of seizures (p = 0.002) as independent predictors of TS, as did receiver operating characteristic analyses, which had a significant area under the curve of 0.66 for the combination of WFNS grade and seizures. For 12 (15.4%) patients, the TS had to be surgically treated by pars plana vitrectomy in a total of 14 eyes, which resulted in significant improvement of visual function in all patients: mean preoperative best-corrected visual acuity was 0.03 (± 0.08) versus 0.76 (± 0.21) postoperatively (p < 0.001). CONCLUSIONS: TS is a common complication in patients with aSAH, affecting approximately one in five patients. A higher WFNS grade and the occurrence of seizures are associated with TS; therefore, screening for TS should be performed in these patients.

The Comprehensive Complication Index (CCI) as a Measure of Postoperative Morbidity and Neurological Outcome after Elective Intracranial Surgery.

BACKGROUND: The Comprehensive Complication Index (CCI) is a numerical scale based on the Clavien-Dindo classification (CDC) and both are widely used to assess outcome. However, the CCI had not been described for neurosurgical procedures. OBJECTIVE: We aimed to investigate the value of the CCI to predict outcome in patients who underwent elective intracranial surgery. METHODS: Prospective cohort study including patients who underwent elective intracranial surgery. Complications were graded using CDC, and the CCI was calculated daily. Neurological outcome was assessed using mRS, NANO, NIHSS, and KPS. RESULTS: Of 294 patients who underwent an elective intracranial procedure, 211 (71.8%) patients underwent a craniotomy, while 28 (9.5%) patients had a burr hole procedure and 55 (18.7%) patients a transsphenoidal approach. A higher blood loss was the only significant predictor for a higher CCI (OR 1.09, 95% CI 1.00-1.12, P < 0.01). Patients with a higher CCI had a longer LOS (mean: 5.4 versus 10.9 days, P < 0.01) and ICU stay (mean: 0.8 versus 2.4 days, P < 0.01). Daily CCI revealed a risk for complications after craniotomies until postoperative day (POD) 7. In patients who underwent brain tumor surgery, the resection of meningiomas and metastasis showed a similar developmental course of CCI. A significantly higher CCI was observed in patients who had a neurological deterioration at discharge ( P < 0.01). CONCLUSION: CCI is a valid scale to measure outcome after intracranial procedures and correlates with neurological outcome. Risk for adverse events after craniotomy is at highest until postoperative day 7.

Single-Center Experience Using a 3D4K Digital Operating Scope System for Aneurysm Surgery.

BACKGROUND: In recent years, 3D4K exoscope systems (EXs) have been introduced to microneurosurgery and reported to be an alternative to conventional operating microscopes (OMs). This study reviews our single-center experience using an 3D4K EX in intracranial aneurysm surgery. OBJECTIVE: To investigate the applicability of a novel 3D4K EX for intracranial aneurysm surgery. METHODS: A retrospective analysis of patients who underwent microsurgical repair of incidentally or ruptured cerebral aneurysms between August 2018 and August 2020 was performed. Patient and aneurysm characteristics and technical features, including 3-dimensional indocyanine green fluorescence, were evaluated. Data on surgery duration were statically assessed for a time trend and comparability with the OM cohort. RESULTS: Overall, we collected 185 aneurysm cases in which the exoscope was used in 44 cases. The mean duration of surgery using the EX was in similar range to those using the OM (165.5 ± 45.8 minutes vs 160.5 ± 39.2 minutes, P > .05). Routine postoperative computed tomography angiography showed comparable rates of complete aneurysm occlusion (95.5% vs 92.2%, P > .05) and postoperative complications (9.1% vs 9.7%, P > .05). There was no necessity to revert to the OM from the EX. Three-dimensional indocyanine green fluorescence was used in all procedures without any malfunction. CONCLUSION: The 3D4K EX for vascular microsurgical cases proved to be as useful as the OM. Because of the ease of use and comparable surgical results, the EX has the potential to become an accepted and additional visualization tool in vascular microsurgery next to the OM.

Aneurysm Location Affects Clinical Course and Mortality in Patients With Subarachnoid Hemorrhage.

Objective: The influence of preexisting factors on the clinical course of patients with subarachnoid hemorrhage (SAH), such as patient age, arterial hypertension, and aneurysm characteristics, is still a matter of debate. However, the specific impact of the exact aneurysm location has not received adequate attention. Therefore, the aim of this study was to investigate the influence of aneurysm location as a preexisting factor on the clinical course and mortality. Methods: The data of consecutive patients with aneurysmal SAH who were treated from October 2010 to July 2020 were retrospectively analyzed. We distinguished four aneurysm locations: the anterior complex, internal carotid artery (ICA), middle cerebral artery (MCA), and posterior circulation. Logistic regression analysis and receiver operating characteristics were used to investigate the influence of aneurysm location on the occurrence of acute hydrocephalus, Delayed Cerebral Ischemia (DCI), neurological outcome, and in-hospital mortality. Neurological outcome was assessed 3 months after discharge using the Glasgow Outcome Scale. Results: A total of 603 patients were included in this study. Patients with MCA aneurysms were 2.52 times less likely to develop acute hydrocephalus compared to patients with anterior complex aneurysms (p = 0.001). Delayed cerebral ischemia occurred most frequently in patients with an anterior complex aneurysm and least frequently in MCA aneurysms (p = 0.014). In ICA aneurysms, mortality was 2.56-fold higher than in patients with aneurysms of the anterior complex (p = 0.006). An additional ROC analysis showed a good prediction for in-hospital mortality when taking the aneurysm's location into account [AUC.855 (CI.817 -0.893)]. Conclusions: The aneurysm's location proved to be a significant predictor of acute hydrocephalus, DCI, and in-hospital mortality, demonstrating the impact of this preexisting biological factor on the course of SAH.

A recurrent machine learning model predicts intracranial hypertension in neurointensive care patients.

The evolution of intracranial pressure (ICP) of critically ill patients admitted to a neurointensive care unit (ICU) is difficult to predict. Besides the underlying disease and compromised intracranial space, ICP is affected by a multitude of factors, many of which are monitored on the ICU, but the complexity of the resulting patterns limits their clinical use. This paves the way for new machine learning techniques to assist clinical management of patients undergoing invasive ICP monitoring independent of the underlying disease. An institutional cohort (ICP-ICU) of patients with invasive ICP monitoring (n = 1346) was used to train recurrent machine learning models to predict the occurrence of ICP increases of ≥22 mmHg over a long (>2 h) time period in the upcoming hours. External validation was performed on patients undergoing invasive ICP measurement in two publicly available datasets [Medical Information Mart for Intensive Care (MIMIC, n = 998) and eICU Collaborative Research Database (n = 1634)]. Different distances (1-24 h) between prediction time point and upcoming critical phase were evaluated, demonstrating a decrease in performance but still robust AUC-ROC with larger distances (24 h AUC-ROC: ICP-ICU 0.826 ± 0.0071, MIMIC 0.836 ± 0.0063, eICU 0.779 ± 0.0046, 1 h AUC-ROC: ICP-ICU 0.982 ± 0.0008, MIMIC 0.965 ± 0.0010, eICU 0.941 ± 0.0025). The model operates on sparse hourly data and is stable in handling variable input lengths and missingness through its nature of recurrence and internal memory. Calculation of gradient-based feature importance revealed individual underlying decisions for our long short time memory-based model and thereby provided improved clinical interpretability. Recurrent machine learning models have the potential to be an effective tool for the prediction of ICP increases with high translational potential.

Safety and Clinical Effects of Switching From Intravenous to Oral Nimodipine Administration in Aneurysmal Subarachnoid Hemorrhage.

Objective: Several guidelines recommend oral administration of nimodipine as vasospasm prophylaxis after aneurysmal subarachnoid hemorrhage (SAH). However, in clinical practice, the drug is administered orally and intravenously (i.v.), depending on clinical conditions and local treatment regimens. We have therefore investigated the safety and clinical effects of switching from i.v. to oral nimodipine therapy. Methods: Patients with aneurysmal SAH between January 2014 and April 2018 and initial i.v. nimodipine therapy, which was subsequently switched to oral administration, were included in this retrospective study. Transcranial Doppler sonography (TCD) of the vessels of the anterior circulation was performed daily. The occurrence of vasospasm and infarction during the overall course of the treatment was recorded. Statistical level of significance was set to p < 0.05. Results: A total of 133 patients (mean age 55.8 years, 65% female) initially received nimodipine i.v. after aneurysmal SAH, which was subsequently switched to oral administration after a mean of 12 days. There were no significant increases in mean flow velocities on TCD after the switch from i.v. to oral nimodipine administration regarding the anterior cerebral artery. For the middle cerebral artery, an increase from 62.36 to 71.78 cm/sec could only be detected in the subgroup of patients with infarction. There was no clustering of complicating events such as new-onset vasospasm or infarction during or after the switch. Conclusions: Our results do not point to any safety concerns when switching nimodipine from initial i.v. to oral administration. Switching was neither associated with clinically relevant increases in TCD velocities nor other relevant adverse events.

Cranial bone flap resorption-pathological features and their implications for clinical treatment.

Cranioplasty following decompressive craniectomy (DC) has a primary complication when using the autologous bone: aseptic bone resorption (ABR). So far, risk factors such as age, number of fragments, and hydrocephalus have been identified but a thorough understanding of the underlying pathophysiology is still missing. The aim of this osteopathological investigation was to gain a better understanding of the underlying processes. Clinical data of patients who underwent surgical revision due to ABR was collected. Demographics, the time interval between craniectomy and cranioplasty, and endocrine serum parameters affecting bone metabolism were collected. Removed specimens underwent qualitative and quantitative histological examination. Two grafts without ABR were examined as controls. Compared to the controls, the typical layering of the cortical and cancellous bone was largely eliminated in the grafts. Histological investigations revealed the coexistence of osteolytic and osteoblastic activity within the necrosis. Bone appositions were distributed over the entire graft area. Remaining marrow spaces were predominantly fibrotic or necrotic. In areas with marrow cavity fibrosis, hardly any new bone tissue was found in the adjacent bone, while there were increased signs of osteoclastic resorption. Insufficient reintegration of the flap may be due to residual fatty bone marrow contained in the bone flap which seems to act as a barrier for osteogenesis. This may obstruct the reorganization of the bone structure, inducing aseptic bone necrosis. Following a path already taken in orthopedic surgery, thorough lavage of the implant to remove the bone marrow may be a possibility, but will need further investigation.

Decompressive craniectomy in malignant MCA infarction in times of mechanical thrombectomy.

BACKGROUND: Mechanical thrombectomies (MT) in stroke have changed the standard treatment regimen with a continuous increase of MTs during the last years. A subsequent reduction in the rates of decompressive craniectomies (DC) as well as a change in clinical characteristics of patients undergoing an additional DC after MT may be assumed. Therefore, objective of this study was to investigate the influence of nowadays regularly performed MT on patients undergoing DC. METHODS: Patients with DC due to cerebral infarctions between January 2009 and January 2018 were included. Patients' clinical presentation and surgical parameters were collected retrospectively. Initial GCS and NIHSS, extent of the stroke, time interval from symptom onset to DC, and neurological outcome were compared between patients with and without thrombectomy. RESULTS: A total of 5469 ischemic strokes were treated in the investigated period, leading to DC in 119 cases (2.2%). A decrease in the rate of performed DCs was recorded: in 2009, 2.8% of ischemic stroke patients underwent surgery compared to 1.9% in 2017. In the meantime, the number of MTs in our center has increased from 84 in 2014 to 160 in 2017. MT was performed in 32 patients prior to DC. No significant differences could be seen between the groups regarding age, initial NIHSS (median 18 in both groups, p = 0.81), extent of the infarctions prior to DC (median ASPECTS 0 in both groups, p = 0.87), time interval from symptom onset to DC, and neurological outcome. CONCLUSIONS: The introduction of routinely performed MT as part of the standard treatment regimen for ischemic stroke has led to a decrease in DCs. However, DC patients with and without MT showed no differences regarding their initial clinical criteria and outcome. These results suggest that earlier DC studies in patients with MCA infarction also apply for the collective of thrombectomized patients.

A Comparison between Pediatric and Adult Patients after Cranioplasty: Aseptic Bone Resorption Causes Earlier Revision in Children.

BACKGROUND AND STUDY AIMS/OBJECTIVE: Cranioplasty, a common neurosurgical intervention following decompressive craniectomy (DC), is associated with high complication rates. Bone flap resorption in particular leads to a considerable number of patients requiring further surgery. The aim of this study was to investigate the frequency and time of occurrence of complications following cranioplastic procedures in children and adults. MATERIAL AND METHODS: Data of children and adults who underwent cranioplasty between July 2010 and March 2018 were analyzed retrospectively. Clinical data, complications, and risk factors regarding aseptic bone resorption (ABR) were evaluated including patient age, occurrence of shunt-dependent hydrocephalus, and number of fragments in autologous bone flaps. RESULTS: Severe traumatic brain injury (TBI) was the leading cause for DC among children (66.7%), associated with a significantly higher number of fragments (p = 0.002). In the adult population, the most common cause was malignant infarction (55.9%) followed by TBI (24.6%). Pediatric patients in our institution received autologous bone flaps less frequently than adult patients (61.1% and 83.1%, respectively). Young age and a higher number of fragments in autologous bone flaps were associated with the occurrence of ABR. Children and adolescents showed significantly higher rates of aseptic bone necrosis (p = 0.007) and revision cranioplasty (p = 0.036). Kaplan-Meier estimates were used to further analyze bone flap resorption in children and adults, showing that revision surgery due to ABR was performed earlier in children (p = 0.001, log-rank test). CONCLUSION: Pediatric patients demand specific care when cranioplasty is performed following DC. We identified age as an independent risk factor. The higher number of fragments appears to be a correlation due to the higher number of TBIs in children. Our data indicate that young age is the most important risk factor for the development of ABR as a frequent and early complication with a shorter revision-free time interval in children. Consequently, the uncritical use of cryopreserved autologous bone flaps should be questioned in this population.

Intracranial pressure in patients undergoing decompressive craniectomy: new perspective on thresholds.

OBJECTIVE Decompressive craniectomy (DC) is an established part of treatment in patients suffering from malignant infarction of the middle cerebral artery (MCA) or traumatic brain injury (TBI). However, no clear evidence for intracranial pressure (ICP)-guided therapy after DC exists. The lack of this evidence might be due to the frequently used, but simplified threshold for ICP of 20 mm Hg, which determines further therapy. Therefore, the objective of this study was to evaluate this threshold's accuracy and to investigate the course of ICP values with respect to neurological outcome. METHODS Data on clinical characteristics and parameters of the ICP course on the intensive care unit were collected retrospectively in 102 patients who underwent DC between December 2007 and April 2014 at the authors' institution. The postoperative ICP course in the first 168 hours was recorded and analyzed. From these findings, ICP thresholds discriminating favorable from unfavorable outcome were calculated using conditional inference tree analysis. Additionally, survival analysis was performed using the Kaplan-Meier method. Prognostic factors were assessed via univariate analysis and multivariate logistic regression. Favorable outcome was defined as a score of 0-4 on the modified Rankin Scale. RESULTS Multivariate logistic regression revealed that anisocoria, diagnosis, and ICP values differed significantly between the outcome groups. ICP values in the favorable and unfavorable outcome groups differed significantly (p < 0.001), while the mean ICP of both groups lay below the limit of 20 mm Hg (17.5 and 11.5 mm Hg, respectively). These findings were reproduced when analyzing the underlying pathologies of TBI and MCA infarction separately. Based on these findings, optimized time-dependent threshold values were calculated and found to be between 10 and 17 mm Hg. These values significantly distinguished favorable from unfavorable outcome and predicted 30-day mortality (p < 0.001). CONCLUSIONS This study systematically evaluated ICP levels in a long-term analysis after DC and provides new, surprisingly low, time-dependent ICP thresholds for these patients. Future trials investigating the benefit of ICP-guided therapy should take these thresholds into consideration and validate them in further patient cohorts.

New Radiologic Parameters Predict Clinical Outcome after Decompressive Craniectomy.

OBJECTIVE: Decompressive craniectomy (DC) is an established part of the management of patients with increased intracranial pressure due to malignant middle cerebral artery (MCA) infarction or traumatic brain injury (TBI). The aim of this study was to determine prognostic radiologic parameters regarding the functional outcome of patients with increased intracranial pressure (ICP) undergoing DC. Special focus was put on the potential differences between malignant MCA infarction and TBI. METHODS: A total of 113 patients were analyzed for their clinical course where preoperative and postoperative radiologic features in computed tomography (CT) scans were correlated to the clinical outcome assessed by the Glasgow Outcome Scale. The difference between presurgical and postsurgical midline shift (ΔMLS) and the ratio between the diameter of the affected and contralateral hemisphere (HDratio) in presurgical and postsurgical CT scans were calculated. RESULTS: ΔMLS (MCA infarction group) and postsurgical HDratio (TBI group) were found to be highly correlating with the clinical outcome on Spearman-correlation testing and underwent further analysis using a binary logistic regression model to evaluate their prognostic value on the outcome, which showed the predictive power of ΔMLS in malignant MCA infarction patients (odds ratio [OR] 0.715; confidence interval [CI] 0.551-0.865). Postsurgical HDratio correlated significantly (OR 0.620; CI 0.384-0.901) with the outcome in the TBI group. CONCLUSION: ΔMLS is an objectifiable parameter, predicting outcome in malignant MCA infarction. In contrast, ΔMLS was of no predictive value in TBI patients. Here postsurgical HDratio serves as a strong predictor of clinical outcome. We recommend applying postsurgical HDratio to TBI patients in order to estimate their clinical outcome and adjust treatment.