Pathogenesis of Chronic Subdural Hematoma: A Cohort Evidencing De Novo and Transformational Origins

Advances in chronic subdural hematoma and membrane imaging

Chronic subdural hematoma (cSDH) is projected to become the most common cranial neurosurgical disease by 2030. Despite medical and surgical management, recurrence rates remain high. Recently, middle meningeal artery embolization (MMAE) has emerged as a promising treatment; however, determinants of disease recurrence are not well understood, and developing novel radiographic biomarkers to assess hematomas and cSDH membranes remains an active area of research. In this narrative review, we summarize the current state-of-the-art for subdural hematoma and membrane imaging and discuss the potential role of MR and dual-energy CT imaging in predicting cSDH recurrence, surgical planning, and selecting patients for embolization treatment.

Synthetic minority over-sampling technique-enhanced machine learning models for predicting recurrence of postoperative chronic subdural hematoma

Objective

Chronic subdural hematoma (CSDH) is a neurological condition with high recurrence rates, primarily observed in the elderly population. Although several risk factors have been identified, predicting CSDH recurrence remains a challenge. Given the potential of machine learning (ML) to extract meaningful insights from complex data sets, our study aims to develop and validate ML models capable of accurately predicting postoperative CSDH recurrence.

Methods

Data from 447 CSDH patients treated with consecutive burr-hole irrigations at Wenzhou Medical University's First Affiliated Hospital (December 2014-April 2019) were studied. 312 patients formed the development cohort, while 135 comprised the test cohort. The Least Absolute Shrinkage and Selection Operator (LASSO) method was employed to select crucial features associated with recurrence. Eight machine learning algorithms were used to construct prediction models for hematoma recurrence, using demographic, laboratory, and radiological features. The Border-line Synthetic Minority Over-sampling Technique (SMOTE) was applied to address data imbalance, and Shapley Additive Explanation (SHAP) analysis was utilized to improve model visualization and interpretability. Model performance was assessed using metrics such as AUROC, sensitivity, specificity, F1 score, calibration plots, and decision curve analysis (DCA).

Results

Our optimized ML models exhibited prediction accuracies ranging from 61.0% to 86.2% for hematoma recurrence in the validation set. Notably, the Random Forest (RF) model surpassed other algorithms, achieving an accuracy of 86.2%. SHAP analysis confirmed these results, highlighting key clinical predictors for CSDH recurrence risk, including age, alanine aminotransferase level, fibrinogen level, thrombin time, and maximum hematoma diameter. The RF model yielded an accuracy of 92.6% with an AUC value of 0.834 in the test dataset.

Conclusion

Our findings underscore the efficacy of machine learning algorithms, notably the integration of the RF model with SMOTE, in forecasting the recurrence of postoperative chronic subdural hematoma. Leveraging the RF model, we devised an online calculator that may serve as a pivotal instrument in tailoring therapeutic strategies and implementing timely preventive interventions for high-risk patients.

Challenges and patient outcomes in chronic subdural haematoma at the level of a regional care system A multi-centre, mixed-methods study from the East of England

BACKGROUND

Chronic subdural haematoma (cSDH) is a common neurosurgical pathology affecting older patients with other health conditions. A significant proportion (up-to 90%) of referrals for surgery in neurosciences units (NSU) come from secondary care. However, the organisation of this care and the experience of patients repatriated to non-specialist centres are currently unclear.

OBJECTIVES

This study aimed to clarify patient outcome in non-specialist centres following NSU discharge for cSDH surgery and to understand key system challenges. The study was set within a representative neurosurgical care system in the east of England.

DESIGN AND METHODS

We performed a retrospective cohort analysis of patients referred for cSDH surgery. Alongside case record review, patient and staff experience were explored using surveys as well as an interactive c-design workshop. Challenges were identified from thematic analysis of survey responses and triangulated by focussed workshop discussions.

RESULTS

Data on 381 patients referred for cSDH surgery from six centres was reviewed. One hundred and fifty-six (41%) patients were repatriated following surgery. Sixty-one (39%) of those repatriated suffered an inpatient complication (new infection, troponin rise or renal injury) following NSU discharge, with 58 requiring institutional discharge or new care. Surveys for staff (n = 42) and patients (n = 209) identified that resourcing, communication, and inter-hospital distance posed care challenges. This was corroborated through workshop discussions with stakeholders from two institutions.

CONCLUSIONS

A significant amount of perioperative care for cSDH is delivered outside of specialist centres. Future improvement initiatives must recognise the system-wide nature of delivery and the challenges such an arrangement presents.

Assessing the accuracy of the International Classification of Disease (ICD) framework in the identification of patients with chronic subdural haematoma from hospital records

BACKGROUND

Chronic subdural hematoma (CSDH) is one of the commonest neurosurgical pathologies with an increasing incidence. Observational studies of routine care have demonstrated high perioperative morbidity and approximately 10% mortality at one year. The development, implementation, and evaluation of a potential care framework relies on an accurate and reproducible method of case identification and case ascertainment. With this manuscript, we report on the accuracy of diagnostic ICD codes for identifying patients with CSDH from retrospective electronic data and explore whether basic demographic data could improve the identification of CSDH.

METHODS

Data were collected retrospectively from the hospital administrative system between 2014 and 2018 of all patients coded with either S065 or I620. Analysis of the ICD codes in identifying patients with CSDH diagnosis was calculated using the caretR package in RStudioR,.and stepwise logistic regression analysis was performed to evaluate the best predictive model for CSDH.

RESULTS

A total of 1861 patients were identified. Of these, 189 (10.2%) had a diagnosis of non-traumatic SDH (I620) and 1672 (89.8%) traumatic subdural haematomas (S065). Variables that identified CSDH as a diagnosis on univariate logistic regression included male sex (Odds Ratios (OR) - 1.606 (1.197-2.161), elderly age (OR) - 1.023 (1.015-1.032) per year for age (p < 0.001) and shorter length of hospital stay. Using stepwise regression against AIC the best model to predict CSDH included male sex, older age, and shorter LOS. The calculated sensitivity for identifying CSDH with the model is 88.4% with a specificity of 84.5% and PPV of 87.9%.

CONCLUSION

CSDH is a common neurosurgical pathology with increasing incidence and ongoing unmet clinical need. We demonstrate that case ascertainment for research purposes can be improved with the incorporation of additional demographic data but at the expense of significant case exclusion.

Protocol for the development of a multidisciplinary clinical practice guideline for the care of patients with chronic subdural haematoma

Introduction: A common neurosurgical condition, chronic subdural haematoma (cSDH) typically affects older people with other underlying health conditions. The care of this potentially vulnerable cohort is often, however, fragmented and suboptimal. In other complex conditions, multidisciplinary guidelines have transformed patient experience and outcomes, but no such framework exists for cSDH. This paper outlines a protocol to develop the first comprehensive multidisciplinary guideline from diagnosis to long-term recovery with cSDH. Methods: The project will be guided by a steering group of key stakeholders and professional organisations and will feature patient and public involvement. Multidisciplinary thematic working groups will examine key aspects of care to formulate appropriate, patient-centered research questions, targeted with evidence review using the GRADE framework. The working groups will then formulate draft clinical recommendations to be used in a modified Delphi process to build consensus on guideline contents. Conclusions: We present a protocol for the development of a multidisciplinary guideline to inform the care of patients with a cSDH, developed by cross-disciplinary working groups and arrived at through a consensus-building process, including a modified online Delphi.

Inflammatory biomarkers differentiate the stage of maturation in chronic subdural hematomas

OBJECTIVE

Inflammation is a major pathophysiological driver of the development of chronic subdural hematomas (CSDH), but there is still limited knowledge on the key molecular processes and corresponding biomarkers involved in this disease. In this study, the aim was to study a subset of inflammatory biomarkers and their relation to the clinical status of the patient and the radiological characteristics of the CSDH.

METHODS

In this observational study, 58 patients who were operated on with CSDH evacuation, at the Department of Neurosurgery, Uppsala, Sweden, between 2019 and 2021, were prospectively included. The CSDH fluid was collected peri-operatively and was later analyzed with proximity extension assay (PEA) technique (Olink) for a panel of 92 inflammatory biomarkers. Demographic, neurological (Markwalder), radiological (general (Nakaguchi classification) and focal (septa below the burr holes)), and outcome variables were collected.

RESULTS

In 84 of the 92 inflammatory biomarkers, the concentration was above the detection limit in >50% of the patients. There was a significant difference in GDNF, NT-3, and IL-8 depending on the Nakaguchi class, with higher values in the trabeculated CSDH subtype. In addition, those with septa at the focal area of CSDH collection, had higher levels of GDNF, MCP-3, NT-3, CXCL1, CXCL5, IL8, and OSM. There was no association between Markwalder grade and the inflammatory biomarkers.

CONCLUSIONS

Our findings support the presence of local inflammation in the CSDH, a shift in biomarker pattern as the CSDH matures towards the trabeculated state, potentially differences in biomarker patterns within the CSDH depending on the focal environment with presence of septa, and that the brain might develop protective mechanisms (GDNF and NT-3) in case of mature and long-standing CSDHs.

Subdural Lesions Linking Additional Intracranial Spaces and Chronic Subdural Hematomas: A Narrative Review with Mutual Correlation and Possible Mechanisms behind High Recurrence

The purpose of this study was two-fold. The first was to investigate the pathologic mechanisms underlying the formation of subdural fluid collection, an umbrella term referring to a condition commonly seen in the clinical setting. Accumulation of the cerebrospinal fluid (CSF) in the subdural space can be referred to in this disease category, disregarding the underlying source of the subdural fluid. However, in these two clinical situations, especially after trauma or brain surgery, fluid collection from the subarachnoid space (subdural hygroma) or from the ventricle to the subarachnoid space and infusion into the subdural space (external hydrocephalus), surgical management of critical patients may adopt the strategies of burr-hole, subduroperitoneal shunt, or ventriculoperitoneal shunt, which present distinctly different thoughts. Crucially, the former can be further transformed into chronic subdural hematoma (CSDH). The second significant theme was the pathogenesis of CSDH. Once the potential dural border cell (DBC) layer is separated such as if a wound is formed, the physiological mechanisms that seem to promote wound healing will resume in the subdural space as follows: coagulation, inflammation, fibroblast proliferation, neovascularization, and fibrinolysis. These aptly correspond to several key characteristics of CSDH formation such as the presence of both coagulation and fibrinolysis signals within the clot, neomembrane formation, angiogenesis, and recurrent bleeding, which contribute to CSDH failing to coagulate and absorb easily. Such a complexity of genesis and the possibility of arising from multiple pathological patterns provide a reasonable explanation for the high recurrence rate, even after surgery. Among the various complex and clinically challenging subdural lesions, namely, CSDH (confined to the subdural space alone), subdural hygroma (linked in two spaces), and external hydrocephalus (linked in three spaces), the ability to fully understand the different pathological mechanisms of each, differentiate them clinically, and devote more interventional strategies (including anti-inflammatory, anti-angiogenic, and anti-fibrinolysis) will be important themes in the future.

Challenges and opportunities in the care of chronic subdural haematoma: perspectives from a multi-disciplinary working group on the need for change

INTRODUCTION

A chronic subdural haematoma (cSDH) is a collection of altered blood products between the dura and brain resulting in a slowly evolving neurological deficit. It is increasingly common and, in high income countries, affects an older, multimorbid population. With changing demographics improving the care of this cohort is of increasing importance.

METHODS

We convened a cross-disciplinary working group (the 'Improving Care in Elderly Neurosurgery Initiative') in October 2020. This comprised experts in neurosurgical care and a range of perioperative stakeholders. An Implementation Science framework was used to structure discussions around the challenges of cSDH care within the United Kingdom. The outcomes of these discussions were recorded and summarised, before being circulated to all attendees for comment and refinement.

RESULTS

The working group identified four key requirements for improving cSDH care: (1) data, audit, and natural history; (2) evidence-based guidelines and pathways; (3) shared decision-making; and (4) an overarching quality improvement strategy. Frequent transfers between care providers were identified as impacting on both perioperative care and presenting a barrier to effective data collection and teamworking. Improvement initiatives must be cognizant of the complex, system-wide nature of the problem, and may require a combination of targeted trials at points of clinical equipoise (such as anesthetic technique or anticoagulant management), evidence-based guideline development, and a cycle of knowledge acquisition and implementation.

CONCLUSION

The care of cSDH is a growing clinical problem. Lessons may be learned from the standardised pathways of care such as those as used in hip fracture and stroke. A defined care pathway for cSDH, encompassing perioperative care and rehabilitation, could plausibly improve patient outcomes but work remains to tailor such a pathway to cSDH care. The development of such a pathway at a national level should be a priority, and the focus of future work.

Peripheral blood eosinophil and classification of residual hematoma help predict the recurrence of chronic subdural hematoma after initial surgery

Chronic subdural hematoma (CSDH) is a common type of intracranial hemorrhage in neurosurgical practice, whose incidence has increased markedly in recent years. However, CSDH still troubles clinicians with a high postoperative recurrence rate. The presence of eosinophils has been confirmed in some CSDH surgical specimens. Furthermore, postoperative residual hematoma has not been classified, and its association with the recurrence of CSDH remains unknown. The present study aimed to test the hypothesis that the peripheral blood eosinophils and the classification of postoperative residual hematoma are significant for the prediction of CSDH recurrence after burr-hole surgery. A retrospective review of 258 CSDH patients who received burr-hole surgery was performed. A complete blood picture with differential count was taken before surgery. Clinical, laboratory, and radiographic factors predicting CSDH recurrence were identified in univariable and multivariable analyses. Univariable analysis showed that the percentage of eosinophils, peripheral blood eosinophil count <0.15 × 10⁹/L, gradation and separated types, postoperative volume of the residual cavity ≥70 ml, residual air volume ≥28 ml, residual hematoma volume ≥55 ml, residual hematoma width ≥1.4 cm, postoperative midline shift ≥5.6 mm, postoperative brain re-expansion rate <41%, postoperative low-density type, and postoperative high-density type correlated with the recurrence of CSDH. Multivariable analysis, however, showed that peripheral blood eosinophil count <0.15 × 10⁹/L, gradation and separated types, preoperative midline shift ≥9.5 mm, postoperative brain re-expansion rate <41%, postoperative low-density type, and postoperative high-density type are independent predictors for the recurrence of CSDH. We expect that peripheral blood eosinophils and the classification of postoperative residual hematoma may facilitate our understanding of the recurrence of CSDH after initial surgery.

Autotaxin Activity in Chronic Subdural Hematoma: A Prospective Clinical Study

Autotaxin (ATX) is the ectoenzyme producing the bulk of lysophosphatidic acid (LPA) in circulation. ATX and LPA-mediated signaling (the ATX-LPA axis) play critical roles in the vascular and nervous system development. In adults, this axis contributes to diverse processes, including coagulation, inflammation, fibroproliferation and angiogenesis under physiological and/or pathophysiological conditions. Given evidence implicating several of these processes in chronic subdural hematoma (CSDH) pathogenesis and development, we assessed ATX activity in CSDH patients. Twenty-eight patients were recruited. Blood and hematoma fluid were collected. Enzymatic assays were used to establish serum and hematoma ATX activity. Enzyme-linked immunosorbent assays were used to establish hematoma beta trace (BT) levels, a cerebrospinal fluid (CSF) marker, in a hematoma. ATX activity was nearly three folds higher in hematoma compared to serum (P < 0.001). There was no significant correlation between BT levels and ATX activity in a hematoma. The present results show, for the first time, that ATX is catalytically active in the hematoma fluid of CSDH patients. Moreover, our findings of significantly elevated ATX activity in hematoma compared to serum, implicate the ATX-LPA axis in CSDH pathophysiology. The CSF origin of ATX could not be inferred with the present results. Additional research is warranted to establish the significance of the ATX-LPA axis in CSDH and its potential as a biomarker and/or therapeutic target.

Post-traumatic headaches and vision: A review

BACKGROUND: Post-traumatic headache is the most common sequela of brain injury and can last months or years after the damaging event. Many headache types are associated with visual concerns also known to stem from concussion. OBJECTIVES: To describe the various headache types seen after head injury and demonstrate how they impact or are impacted by the visual system. METHODS: We will mirror the International Classification of Headache Disorders (ICHD) format to demonstrate the variety of headaches following brain injury and relate correlates to the visual pathways. The PubMed database was searched using terms such as headache, head pain, vision, concussion, traumatic brain injury, glare, visuomotor pathways. RESULTS: Every type of headache described in the International Classification of Headache Disorders Edition III can be initiated or worsened after head trauma. Furthermore, there is very often a direct or indirect impact upon the visual system for each of these headaches. CONCLUSION: Headaches of every described type in the ICHD can be caused by brain injury and all are related in some way to the afferent, efferent or association areas of the visual system.

Cerebrospinal fluid leak as a driving factor in chronic subdural hematoma formation: A histological study

Background:

Chronic subdural hematoma (CSDH) represents the most common neurosurgical disease. Given the demographic shift toward an aging population, the overall incidence of this condition is increasing. Nevertheless, clarity in the pathophysiological process is yet to be made. Several etiological mechanisms have been proposed to initiate and consequently promote fluid collection in the subdural space. Traumatic injury of the bridging veins has long been considered the primum movens of the pathology but increasing evidence shows that trauma is not the only factor involved. Along with recent advances we sought to understand the role of the cerebrospinal fluid (CSF) in the buildup of the intense inflammatory reaction that characterizes CSDH.

Methods:

In the present study, we examined histological features of reactive membranes secondary to extracranial CSF leakage with CSDH-related membranes. Similarity and differences between the specimens were examined by means of light microscopy.

Results:

Histological similarities were consistently found between CSDH membranes and reactive membranes secondary to CSF leakage in the extracranial space. Activated histiocytes were highlighted in all specimens along with an intense inflammatory reaction.

Conclusion:

CSDH is most likely the result of a complex interaction among different pathophysiological events resulting from both traumatic and inflammatory etiologies. In the present work, we highlight how CSF leakage could be an early factor that leads to a cascade of events that culminates in CSDH formation.

Microvascular proliferation in the clots: The key finding of acute subdural hematoma transforming into chronic subdural hematoma?

Background:

Despite extensive investigations, the exact etiology of chronic subdural hematoma (CSDH) remains elusive. Organized CSDHs are a distinct but less-understood type of CSDH.

Case Description:

A 50-year-old hypertensive woman experienced headache without any previous head injury. At presentation, the patient showed no focal neurological deficits. Cranial computed tomography (CT) revealed a slightly compressive subdural hematoma that spontaneously regressed and no intracranial vascular lesions. Cerebral magnetic resonance imaging identified a non-enhancing nodular lesion in the subdural hematoma. After the patient presented disorientation and aphasia on post hospitalization day 14, CT showed a considerable enlargement of the subdural hematoma. Partial removal of the bi-layered hematoma was performed through a parietal craniotomy. Histological examination revealed microvascular proliferation in both the outer membrane and the nodular lesion. On postoperative day 35, CT demonstrated a remarkable resolution of the residual hematoma.

Conclusion:

Development of microvascular proliferation in the clots of an acute subdural hematoma may lead to its rapid enlargement as an organized CSDH. Organized CSDH can be managed by partial removal of the outer membrane and hematoma through a craniotomy.