Production of clinical form of chronic subdural hematoma in experimental animals

A novel swine model of selective middle meningeal artery catheterization and embolization

BACKGROUND

Middle meningeal artery (MMA) embolization is a promising intervention as a stand-alone or adjunct treatment to surgery in patients with chronic subdural hematomas. There are currently no large animal models for selective access and embolization of the MMA for preclinical evaluation of this endovascular modality. Our objective was to introduce a novel in vivo model of selective MMA embolization in swine.

METHODS

Diagnostic cerebral angiography with selective microcatheter catheterization into the MMA was performed under general anesthesia in five swine. Anatomical variants in arterial meningeal supply were examined. In two animals, subsequent embolization of the MMA with a liquid embolic agent (Onyx-18) was performed, followed by brain tissue harvest and histological analysis.

RESULTS

The MMA was consistently localized as a branch of the internal maxillary artery just distal to the origin of the ascending pharyngeal artery. Additional meningeal supply was observed from the external ophthalmic artery, although not present consistently. MMA embolization with Onyx was technically successful and feasible. Histological analysis showed Onyx material within the MMA lumen.

CONCLUSIONS

Microcatheter access into the MMA in swine with liquid embolic agent delivery represents a reproducible model of MMA embolization. Anatomical variations in the distribution of arterial supply to the meninges exist. This model has a potential application for comparing therapeutic effects of various embolic agents in a preclinical setting that closely resembles the MMA embolization procedure in humans.

Time-of-flight magnetic resonance angiography for detection of postoperative recurrence in patients with chronic subdural hematoma

PURPOSE

Chronic subdural hematoma (CSDH) is associated with postoperative recurrence. Although various factors are involved in postoperative recurrence of CSDH, blood flow, especially in the middle meningeal artery (MMA), is considered to play an important role. We investigated whether the degree of signal intensity (SI) of the MMA on time-of-flight magnetic resonance angiography (TOF MRA) and various clinical factors are involved in recurrence of CSDH.

METHODS

The maximum SI of both MMAs was measured on TOF MRA images within 1 month before or after the initial surgery.

RESULTS

In total, 185 patients (20 with and 165 without recurrence of CSDH) were included in the analysis. The SI ratio and dementia were significant predictors of recurrence of CSDH (SI ratio: odds ratio [95% confidence interval (CI)] = 1.71 [1.32, 2.22], p < 0.0001; dementia: odds ratio [95% CI] = 7.41 [1.83, 30.1], p = 0.005). The estimated regression coefficients in the final model were 6.14 for the SI ratio and 1.28 for dementia. The risk score was derived according to these regression coefficients as follows: score = 5 × SI ratio + 1 (dementia: yes). With a score of 5, the predicted probability of recurrence was 2% [95% CI 0.7, 5.7], whereas with scores of 8 and 10, the probability was 43.3% [27.0, 61.1] and 89.5% [65.7, 97.5], respectively, which increased the risk of recurrence.

CONCLUSION

Patients with an increased SI ratio of the affected MMA on TOF MRA who underwent surgery for CSDH were significantly more likely to experience recurrence.

Understanding Subdural Collections in Pediatric Abusive Head Trauma

Life-threatening physical abuse of infants and toddlers is frequently correlated with head injuries. A common variant of the abusive head trauma is the shaken baby syndrome. The present review article sheds light on subdural collections in children with abusive head trauma and aims at providing a recent knowledge base for various medical disciplines involved in diagnostic procedures and legal proceedings. To this end, the different subdural collection entities are presented and illustrated. The pathophysiologic background is explained. Differential and age-diagnostic aspects are discussed and summarized by tabular and graphic overviews. Two problematic constellations frequently occurring during initial CT investigations are evaluated: A mixed-density subdural collection does not prove repeated trauma, and hypodense subdural collections are not synonymous with chronicity. The neuroradiologic analysis and assessment of subdural collections may decisively contribute to answering differential diagnostic and forensic questions. In addition to more reference data, a harmonization of terminology and methodology is urgently needed, especially with respect to age-diagnostic aspects.

Postoperative Subdural Air Collection Is a Risk Factor for Chronic Subdural Hematoma after Surgical Clipping of Cerebral Aneurysms

The precise mechanism of the development of chronic subdural hematoma (CSDH) as a postoperative complication after aneurysmal clipping remains unclear. The purpose of this study was to identify the independent risk factors for CSDH after craniotomy for aneurysmal clipping and to elucidate the relationship between CSDH and subdural air (SDA) collection immediately after surgery. The medical records and radiologic data of 344 patients who underwent surgical clipping of unruptured aneurysms from July 2010 to July 2016 were retrospectively evaluated. Patient characteristics, aneurysm characteristics, and operation data were statistically analyzed to reveal their relationships with CSDH development. Among the 344 patients, 46 (13.4%) developed CSDH and 13 (3.8%) required subsequent burr-hole surgery for evacuation and irrigation. Multivariate analyses showed that advanced age (P < 0.0001), male sex (P = 0.035), and surgical clipping of multiple aneurysms (P = 0.037) were independent preoperative predictors of CSDH development. Advanced age (P = 0.0005) and postoperative SDA after clipping surgery (P < 0.0001) were independent postoperative predictors of CSDH development. Postoperative SDA and CSDH were not associated with the individual surgeon or operation time. Postoperative severe SDA was significantly associated with the ipsilateral development of CSDH, irrespective of the side of craniotomy. Postoperative SDA is an independent risk factor for CSDH after surgical clipping of unruptured aneurysms and is as important as advanced age, male sex, and surgical clipping of multiple aneurysms in predicting CSDH.

Chronic Subdural Hematoma: A Historical and Clinical Perspective

BACKGROUND

This review aims to highlight the clinical complexity of chronic subdural hematoma (cSDH) while presenting a brief historical discussion of cSDH.

METHODS

A thorough literature search of published English-language papers was performed in PubMed, Ovid, and Cochrane databases.

RESULTS

cSDH affects 1-5.3 per 100,000 individuals annually, with the incidence expected to rise as the U.S. population ages. The symptoms of cSDH are often nonspecific, with headaches being the most common complaint. Other symptoms include weakness, balance and gait problems, and memory problems.

CONCLUSIONS

A variety of clinical factors must be taken into account in the treatment of cSDH, and the multifaceted treatment paradigms continue to evolve.

Role of cathepsin K in the development of chronic subdural hematoma

Despite extensive investigations, the process of development of chronic subdural hematoma (CSDH) is not known. The present study aims to investigate CSDH by measuring biomarkers in it, gas analysis, and immunohistochemical examination. A total of 42 patients with symptomatic CSDH who underwent burr-hole drainage were enrolled. Intraoperatively, hematoma fluid and peripheral venous blood (PV_CSDH) were simultaneously collected. As controls, peripheral venous blood (PV_Control) and intracranial cerebrospinal fluid (CSF) were collected from other subjects during other surgeries. CatK, lipocalin-type prostaglandin D synthase (PGDS), and cystatin C (CysC) present in these specimens were measured using enzyme-linked immunosorbent assay. Data obtained were statistically analyzed after age correction. In 15 patients, gas analysis was performed for CSDH and PV_CSDH. Furthermore, immunohistochemical examination for the outer membrane was performed for four patients. CatK, PGDS, and CysC levels were markedly elevated in the CSF and CSDH. CatK levels in PV_CSDH were significantly higher than in PV_Control (P<0.0001). In contrast, CysC levels in PV_CSDH were significantly lower than in PV_Control (P=0.004). The gas analysis revealed that the internal environment of CSDH is characterized by marked hypoxia, hypoglycemia, and lactic acidosis. Furthermore, the outer membrane consistently showed a diffuse staining for CatK. Based on these, CatK was thought to play a role in the development of CSDH, with the levels in peripheral venous blood elevated in patients with CSDH.

Analysis of Risk Factor for the Development of Chronic Subdural Hematoma in Patients with Traumatic Subdural Hygroma

OBJECTIVE

Although a high incidence of chronic subdural hematoma (CSDH) following traumatic subdural hygroma (SDG) has been reported, no study has evaluated risk factors for the development of CSDH. Therefore, we analyzed the risk factors contributing to formation of CSDH in patients with traumatic SDG.

METHODS

We retrospectively reviewed patients admitted to Hallym University Hospital with traumatic head injury from January 2004 through December 2013. A total of 45 patients with these injuries in which traumatic SDG developed during the follow-up period were analyzed. All patients were divided into two groups based on the development of CSDH, and the associations between the development of CSDH and independent variables were investigated.

RESULTS

Thirty-one patients suffered from bilateral SDG, whereas 14 had unilateral SDG. Follow-up computed tomography scans revealed regression of SDG in 25 of 45 patients (55.6%), but the remaining 20 patients (44.4%) suffered from transition to CSDH. Eight patients developed bilateral CSDH, and 12 patients developed unilateral CSDH. Hemorrhage-free survival rates were significantly lower in the male and bilateral SDG group (log-rank test; p=0.043 and p=0.013, respectively). Binary logistic regression analysis revealed male (OR, 7.68; 95% CI 1.18-49.78; p=0.033) and bilateral SDG (OR, 8.04; 95% CI 1.41-45.7; p=0.019) were significant risk factors for development of CSDH.

CONCLUSION

The potential to evolve into CSDH should be considered in patients with traumatic SDG, particularly male patients with bilateral SDG.

Atorvastatin enhances angiogenesis to reduce subdural hematoma in a rat model

BACKGROUND AND PURPOSE

Statins are active in reducing plasma lipids, suppressing inflammation and promoting angiogenesis. Because angiogenesis is critical for the absorbance of subdural hematoma (SDH), we hypothesize that atorvastatin promotes angiogenesis to enhance hematoma absorption.

METHODS

SDH was induced in adult Wistar rats and treated with 3mg/kg, 8mg/kg of atorvastatin, or vehicle saline daily for 7days. The treated rats were examined for the level of CD34+/CD133+ endothelial progenitor cells (EPCs) in the circulation by flow cytometry, hematoma volumes by magnetic resonance imaging (MRI), and changes in cognitive functions. We also examined angiogenesis in the hematoma wall by transmission electronic microscopy and immunohistochemistry for the expression of vascular endothelial growth factor (VEGF), matrix metalloprotease 9 (MMP 9) and angiopoietin.

RESULTS

SDH volume was significantly reduced and neurological deficits improved in rats receiving the low dose atorvastatin compared to those receiving either the high dose of atorvastatin or saline. Consistent with these outcome measures, the low dose atorvastatin increased the expression of angiopoient-1 and VEGF and reduced MMP9 expression in the connective tissue of the SDH wall, resulting in an increased vascular density and enhanced vascular maturation.

CONCLUSIONS

The low-dose atorvastatin is effective in reducing SDH and improving neurological deficits in a rat model, primarily by promoting angiogenesis and vascular maturation.

History of Chronic Subdural Hematoma

Trephination or trepanation is an intentional surgical procedure performed from the Stone Age. It looks like escaping a black evil from the head. This technique is still used for treatment of chronic subdural hematoma (SDH). Now, we know the origin, pathogenesis and natural history of this lesion. The author try to explore the history of trephination and modern discovery of chronic SDH. The author performed a detailed electronic search of PubMed. By the key word of chronic SDH, 2,593 articles were found without language restriction in May 2015. The author reviewed the fact and way, discovering the present knowledge on the chronic SDH. The first authentic report of chronic SDH was that of Wepfer in 1657. Chronic SDH was regarded as a stroke in 17th century. It was changed as an inflammatory disease in 19th century by Virchow, and became a traumatic lesion in 20th century. However, trauma is not necessary in many cases of chronic SDHs. The more important prerequisite is sufficient potential subdural space, degeneration of the brain. Modifying Virchow's description, chronic SDH is sometimes traumatic, but most often caused by severe degeneration of the brain. From Wepfer's first description, nearly 350 years passed to explore the origin, pathogenesis, and fate of chronic SDH. The nature of the black evil in the head of the Stone Age is uncovering by many authors riding the giant's shoulder. Chronic SDH should be categorized as a degenerative lesion instead of a traumatic lesion.

A rat model of chronic subdural hematoma: Insight into mechanisms of revascularization and inflammation

Chronic subdural hematoma (CSDH) is a common neurological occurrence in the elderly population with significant impact on the quality of life and work. Studies have attempted to determine the risk factors and pathophysiological mechanisms of CSDH using models in numerous mammalian species. To date, these animal models have only been able to reproduce limited durations of hematoma which does not accurately reflect the chronic state of CSDH. To address some of these challenges we modified a rat model of CSDH using two consecutive injections of autologous blood resulting in a hematoma of more than three weeks. We observed inflammatory and angiogenic changes related to the development and recovery of CSDH. In this study the technique for producing a CSDH in a small animal model had a success rate of 78.13%. The hematoma was sustainable up to 24 days. Hematoma resolution was associated with a gradual decrease in local pro-inflammatory factors and gradual increase in anti-inflammatory factors as well as proliferation and subsequent maturation of newly formed vessels. These events were also associated with improved behavioral outcome. Expression of anti-inflammatory cytokines also paralleled reabsorption of the hematoma. Reduction in hematoma size was also associated with neurological recovery. These data suggest that vessel maturation and anti-inflammatory pathways may contribute to the resolution of CSDH and neurological recovery. The regulation of the two mechanisms is a potential target for the treatment of CSDH. The modified model of rat CSDH demonstrated a high level of reproducibility in our hands and may be useful in future CSDH studies.

Intraoperative Arachnoid Plasty Has Possibility to Prevent Chronic Subdural Hematoma after Surgery for Unruptured Cerebral Aneurysms

Some patients develop chronic subdural hematomas (CSDHs) after the clipping/coating of unruptured aneurysms. The risk factors are not well understood and while no preventive methods are currently available, arachnoid plasty (ARP) may intercept the development of postoperative CSDH. We investigated the risk factors for CSDH and the usefulness of ARP to prevent postoperative CSDH. Between January 2009 and June 2013, 393 patients underwent 416 aneurysm surgeries via the pterional approach at Kushiro Kojinkai Memorial Hospital. Of these, 394 aneurysms (371 patients) were included in this study. Using multivariate analysis we evaluated the relationship between the patient demographics and clinical characteristics, and the development of postoperative symptomatic CSDH. We also studied the effect of ARP performed during aneurysm surgery. We found that symptomatic CSDH developed after 20 (5.1%) of the 394 operations; it was addressed by burr hole surgery and evacuation/irrigation. Male gender, advanced age, and oral anticoagulant therapy were significant risk factors for CSDH. Additive ARP, performed in the course of 132 surgeries (33.5%) was found to be a significant negative risk factor. The incidence of CSDH was significantly lower in patients who had undergone ARP than in patients who had not undergone it (0.8% vs. 7.3%, p < 0.01). We first report that ARP is useful for the prevention of CSDH in patients treated by aneurysm surgery.

Efficacy of arachnoid plasty with collagen sheets and fibrin glue: An in vitro experiment and a case review

Background:

Postoperative subdural fluid collection sometimes occurs after clipping of cerebral aneurysms. Arachnoid plasty is used to prevent such postoperative complications; however, the optimal materials for arachnoid plasty remain unclear. In this study, we aimed to clarify the optimal materials for arachnoid plasty and report our experience of arachnoid plasty after clipping of unruptured aneurysms.

Methods:

In an in vitro experiment, adhesive strengths of three materials permitted for use in the intradural space, such as collagen sheets, gelatin sponge, and oxidized cellulose sheets, were measured by assessing their water pressure resistance. Then, 80 consecutive cases surgically treated unruptured cerebral aneurysms were retrospectively reviewed to examine the occurrence rate of postoperative subdural fluid collection.

Results:

The collagen sheet exhibited the greatest adhesive strength, so we used collagen sheets for the arachnoid plasty procedures. In all of these cases, arachnoid plasty was performed with fibrin glue-soaked collagen sheets. No postoperative subdural fluid collection, inflammation, or allergic reactions occurred in any case.

Conclusions:

The present study suggests that collagen sheet might be one of the optimal materials for arachnoid plasty. This technique is simple and may be effective to prevent subdural fluid collection after clipping.

Subdural hygromas in abusive head trauma: pathogenesis, diagnosis, and forensic implications

Are subdural hygromas the result of abusive head trauma? CT and MR imaging represent important tools for the diagnosis of abusive head trauma in living infants. In addition, in-depth understanding of the pathogenesis of subdural hygromas is increasingly required by neuroradiologists, pediatricians, and forensic physicians. Therefore, the current knowledge on subdural hygromas is summarized and forensic conclusions are drawn. The most important diagnostic pitfalls, benign enlargement of the subarachnoid space, and chronic subdural hematoma, are discussed in detail. Illustrative cases from forensic practice are presented. Literature analysis indicates that subdural hygromas can occur immediately or be delayed. If other infrequent reasons can be excluded, the presence of subdural hygromas strongly suggests a posttraumatic state and should prompt the physician to search for other signs of abuse. To differentiate subdural hygromas from other pathologies, additional MR imaging of the infant's head is indispensable after initial CT scan.

Developing a model of chronic subdural hematoma

Chronic subdural hematoma (CSDH) is a common neurosurgical condition that has a high incidence in the increasing elderly population of many countries. Pathologically, it is defined as a persistent liquefied hematoma in the subdural space more than 3 weeks old that is generally encased by a membraneous capsule. CSDHs likely originate after minor head trauma, with a key factor in its development being the potential for a subdural cavity to permit its expansion within, which is usually due to craniocerebral disproportion. The pathogenesis of CSDH has been attributed to osmotic or oncotic pressure differences, although measurements of these factors in the CSDH fluid do not support this theory. Current belief is that CSDH arises from recurrent bleeding in the subdural space, caused by a cycle of local angiogenesis, inflammation, coagulation and ongoing fibrinolysis. However, because of a lack of detailed knowledge about the precise mechanisms, treatment is often limited to surgical interventions that are invasive and often prone to recurrence. Thus, it is possible that an easily reproducible and representative animal model of CSDH would facilitate research in the pathogenesis of CSDH and aid with development of treatment options.

Influence of cranial morphology on the location of chronic subdural haematoma

BACKGROUND

The purpose of the present study was to evaluate the relationship between cranial morphology and location of a chronic subdural haematoma (CSDH) in patients with and without intracranial vault asymmetry.

METHOD

The study was conducted in 110 consecutive adult patients who underwent surgery for CSDH. The relationship between the following variables and CSDH was studied: sex, age, past medical history, history of trauma, interval between head injury and symptoms, clinical presentation, location of the CSDH, symmetry of the frontal and occipital intracranial vault on the CT scan and/or MR images, surgical treatment and outcome. Throughout the analysis, p < 0.05 was considered statistically significant.

FINDINGS

The frontal cranial vault was symmetrical in 48 patients (43.6%) and asymmetrical in 62 patients (56.4%). CSDH was more commonly bilateral in patients with a symmetrical frontal cranial vault than those with an asymmetrical shape (41.7% vs 17.7% and this difference is statistically significant (p = 0.01). In 62 patients with an asymmetric frontal skull vault, the CSDH was bilateral in 11 patients. In the remaining 51 patients, the CSDH was located on the same side of the most curved frontal convexity in 34 patients and on the side of the less curved frontal convexity in 17 patients. The occipital cranial vault was symmetrical in 44 patients (40%) and asymmetrical in 66 patients (60%). CSDH was more commonly bilateral in patients with a symmetrical occipital cranial vault than those with an asymmetrical one (40.9% vs 19.7%) and this difference was also statistically significant (p = 0.019). In 66 patients with an asymmetric occipital skull vault, the CSDH was bilateral in 13 patients. In the remaining 53 patients, the CSDH located on the same side of the most curved occipital convexity in 39 patients and on the side of the less curved occipital convexity in 14 patients.

CONCLUSIONS

Frontal and occipital intracranial vault morphology provides valuable information about location of CSDH. Bilateral CSDH is common in patients with symmetrical frontal and occipital cranial vault. In asymmetrical cranium, CSDH usually locates on the same side of the most curved frontal or occipital convexity. Identification of this relationship can be very useful to elucidate the origin and the pathogenesis of CSDH.

The role of exudation in chronic subdural hematomas

Object

Chronic subdural hematomas (SDHs) are a local inflammatory process that causes the formation of a granulation tissue often referred to as the external or outer membrane. This membrane has abnormally permeable macrocapillaries. Therefore, exudation from the macrocapillaries in the outer membrane of chronic SDH may play an important role in the enlargement of chronic SDH. In this study the authors investigated the role of exudation in chronic SDH.

Methods

The authors examined 24 patients (16 men and eight women; age range 38–86 years [mean age 61.4 years]) with 27 chronic SDHs. The clinical status of the patients was evaluated according to the classification described by Markwalder. The diagnosis was established on computed tomography (CT) scans in all cases. The authors also used the Nomura Classification for judging the lesion's appearance on CT scans. Immediately after the diagnosis, all patients were administered 20 mCi (740 mBq) technetium-99m human serum albumin. Four hours later, blood and SDH samples were taken and radioactivity levels were measured in each. The ratio of activity of the samples taken from chronic SDH to the radioactivity of blood was determined as a percentage and defined as the exudation rate. On the follow-up CT scan obtained on postoperative Day 20, subdural collections thicker than 5 mm were determined to be a reaccumulation.

Results

The correlations between the exudation rate and age of the patients, clinical grades, CT appearances, and amount of reaccumulation were investigated. In this series the average exudation rate was 13.24% (range 2.05–28.88%). The mean exudation rates according to the clinical grades assigned to patients were as follows: Grade 0, 8.67 ± 5.64% (three patients); Grade 1, 5.07 ± 1.43% (eight patients); Grade 2, 17.87 ± 3.73% (seven patients); and Grade 3, 19.65 ± 7.67% (six patients). Exudation rates in patients with Grades 2 and 3 were significantly higher than those in Grades 0 and 1 (p < 0.05).

The mean exudation rates according to the lesion's appearance on CT scans were found as follows: hypodense appearance, 6.55 ± 4.52% (eight patients); isodense appearance, 11.07 ± 6.32% (five patients); hyperdense appearance, 19.47 ± 13.61% (three patients); and mixed-density appearance, 17.40 ± 5.80% (nine patients). The differences among the groups were significant (p < 0.05). The average exudation rate was statistically higher in the patients with reaccumulation (16.30 ± 8.16%) than that in the patients without reaccumulation (9.96 ± 6.84%) (p < 0.05).

Conclusions

The exudation rate in chronic SDH is correlated with a higher clinical grade (Markwalder Grade 2 or 3), mixed-density CT appearance, and reaccumulation. Therefore, exudation from macrocapillaries in the outer membrane of chronic SDH probably plays an important role in the pathophysiology and the growth of chronic SDH.

Morphological aspects of the traumatic chronic subdural hematoma capsule: SEM studies

The morphology of the outer and inner membranes of traumatic chronic subdural hematomas (CSDHs) surgically removed from eight patients was investigated by scanning electron microscopy (SEM). Hematomas were divided into three groups based on time that had passed from the initiation of trauma to surgery. Structure of the CSDHs showed gradual morphological changes of the developing hematoma capsule. They initially included angiogenic and aseptic inflammatory reactions followed by progressive involvement of fibroblasts-proliferating and producing collagen fibrils. Numerous capillaries suggesting formation of new blood vessels were observed mainly in young hematomas removed between 15 and 21 days after trauma. In "older" hematomas (40 days after trauma), more numerous capillaries and thin-walled sinusoids were accompanied by patent, larger diameter blood vessels. Within the fibrotic outer membrane of the "oldest" hematoma capsules (60 or more days after trauma), especially in the area over the hematoma cavity, blood vessels were frequently occluded by clots. The results suggest dynamic changes in cellular and vascular organization of traumatic CSDH capsules paralleling the progression in hematoma age.

Chronic subdural hematomas--causes of morbidity and mortality

OBJECTIVE

Chronic subdural hematoma is a very common condition seen usually in the later stages of life. Treatment, although apparently simple, is associated with some morbidity and mortality with a potential for recurrence. This is especially important as the average life span of humanity increases all over the world.

METHODS

A retrospective analysis of 647 cases of chronic subdural hematomas treated in NIMHANS was done. The aim of this study was to determine the factors responsible for the morbidity, mortality, and recurrence in patients with chronic subdural hematomas.

RESULTS

The patients were mostly men in the sixth and seventh decade of life and presented with headache, cognitive decline, or focal deficits. CT scan was done in all cases. 94% of the patients underwent evacuation of the hematoma. There was a mortality rate of 5%, and there was a recurrence of 21%. Statistical analysis for factors both for mortality and morbidity were done.

CONCLUSIONS

It was seen that statistically significant factors determining mortality were age, GCS at presentation, and associated illnesses like cardiac and renal failure. The statistically significant factors for recurrence are the presence of a thick subdural membrane visualized during surgery and brain, remaining at a depth at the end of evacuation of hematoma. Use of a subdural drain significantly reduced recurrences. The chronicity of the hematoma was not a factor determining mortality or morbidity. Drains were seen to significantly reduce recurrence in younger patients with better GCS and when the subdural membrane is seen at surgery and the brain remains at a depth at the end of hematoma evacuation.

What are the causative factors for a slow, progressive enlargement of a chronic subdural hematoma?

PURPOSE

To test the hypothesis that chronic subdural hematoma (CSDH) enlarges by the causative factors, this study has performed.

MATERIALS AND METHODS

In 10 patients with CSDH, coagulation factors in venous blood taken at the time of surgery and hematomic contents aspirated from the CSDH were studied, using both laboratory assays and microscopy.

RESULTS

When compared to the range of normal plasma, the hematoma fluids demonstrated a marked reduction in factor II, V, VII, VIII, and X, moderate reduction of factors IX and XI, and slight reduction of factor XII. Activated protein C and antithrombin III levels were decreased. The FDP (Fibrinogen Degradation Product) levels in chronic subdural hematoma were extremely high. The endothelial cells of the macrocapillaries (also called ''sinusoid'') showed numerous gap junctions between adjacent endothelial cells and a thinness or absence of the basement membrane, suggesting that the macrocapillaries are very fragile and susceptible to bleeding.

CONCLUSION

Excessive coagulation in the hematoma, predominantly via the extrinsic clotting pathway, local hyperfibrinolysis, transmitted pulsations, and characteristics of the macrocapillaries play an important role in the leakage of blood and the enlargement of CSDH.

Chronic subdural hematoma in patients with idiopathic thrombocytopenic purpura: a case report and review of the literature

BACKGROUND

cSDH is a rare form of bleeding in patients with ITP. Intracerebral hematoma or subarachnoid hemorrhage is more frequently reported in these patients. Spontaneous resolution of cSDH in patients with idiopathic subdural hematoma is uncommon.

CASE DESCRIPTION

We report a case of spontaneous cSDH in a patient with ITP, and we review the related cases in the literature. In our patient, the hematoma resolved spontaneously despite very low platelet levels. There also was an incidental left parietal convexity meningioma. A review of the literature is presented, and the management of the patients is discussed.

CONCLUSION

In patients with ITP, cSDHs may resolve spontaneously or with medical treatment, and surgery might be deferred except in emergency conditions or in patients with normal neurological findings. Close neurological and radiological observation along with the medical treatment may be appropriate in the management of patients with normal neurological findings.

Intracranial hemorrhage and rebleeding in suspected victims of abusive head trauma: addressing the forensic controversies

Does an expanded subarachnoid space predispose to subdural bleeding? What does heterogeneity in the appearance of a subdural collection on CT or MRI imaging indicate? Spontaneous rebleeding? Minor re-injury? Major re-injury? In some specific cases, answers to these questions have important forensic implications. To conclude objectively that an infant's intracranial hemorrhage or rebleeding resulted from inflicted injury or re-injury requires an in-depth understanding of the pathogenesis of posttraumatic subdural and subarachnoid collections. The authors present two cases of indoor, accidental, pediatric, closed-head trauma that resulted in intracranial rebleeding. Both accidental cranial impacts occurred in medical settings and were independently witnessed by medical personnel. In addition, the authors summarize the relevant medical literature regarding pediatric intracranial bleeding and rebleeding.

Arachnoid cyst is a risk factor for chronic subdural hematoma in juveniles: twelve cases of chronic subdural hematoma associated with arachnoid cyst

Chronic subdural hematoma (CSDH) tends to occur in elderly patients with a history of mild head injury at a few months prior to the onset of symptoms. Intracranial arachnoid cyst is believed to be congenital and sometimes becomes symptomatic in pediatric patients. These two distinct clinical entities sporadically occur in the same young patient. Twelve of 541 cases of CSDH surgically treated in our institution had associated arachnoid cyst. The clinical and radiological characteristics of the cases of CSDH associated with arachnoid cyst were retrospectively analyzed and compared with those of CSDH without arachnoid cyst. Arachnoid cysts were located in the middle fossa (eight cases), convexity (two cases), and posterior fossa (two cases). Three cysts were less than 20 mm in diameter. The 12 patients with CSDH and arachnoid cyst (mean age 27.8 +/- 19.7 years) were significantly younger (p < 0.001) than the patients with CSDH without arachnoid cyst (69.5 +/- 13.7 years). Five of the 12 patients were pediatric cases (< 15 years old). The clinical symptoms were also significantly different. The most frequent symptom was headache followed by vomiting in the patients with arachnoid cyst, while gait disturbance and hemiparesis predominated in patients without arachnoid cyst. Hematoma evacuation through burr holes improved the symptoms in all patients with arachnoid cyst. We conclude that even a small arachnoid cyst can be a risk factor for CSDH after mild head injury in young patients and symptoms of increased intracranial pressure are common. Hematoma evacuation is adequate at first operation. If the preoperative symptoms persist, additional arachnoid cyst surgery should be considered. The present results also suggest that CSDH formation may be preceded by subdural hygroma caused by the rupture of arachnoid cyst.

Surgical treatment of chronic subdural hematoma in 500 consecutive cases: clinical characteristics, surgical outcome, complications, and recurrence rate

Chronic subdural hematoma (CSDH) is one of the most common clinical entities in daily neurosurgical practice. The diagnosis and treatment are well established, but recurrence, complications, and factors related to these problems, especially in the elderly, are not completely understood. This study evaluated the clinical features, radiological findings, and surgical results in a large series of the patients treated at the same institution. 500 consecutive patients (359 men and 141 women) with CSDH were treated by burr hole craniostomy with closed system drainage from January 1987 through February 1999. Causes, clinical and computed tomographic findings, surgical results, re-expansion of brain after surgery, and hematoma recurrence were statistically analyzed to elucidate the potential risks of CSDH. Most patients (89.4%) had good recovery, 8.4% showed no change, and 2.2% worsened. Six patients (1.2%) died, three due to disseminated intravascular coagulation. Recurrence of hematoma was recognized in 49 patients (9.8%), at 1 to 8 weeks (3.5 +/- 1.9 weeks) after the first operation. The brain re-expansion rate at one week after operation was 45.0 +/- 21.4% in patients with hematoma recurrence and significantly lower than 55.3 +/- 19.1% in patients without recurrence (p < 0.001). Old age, pre-existing cerebral infarction, and persistence of subdural air after surgery were significantly correlated with poor brain re-expansion (p < 0.001). Twenty-seven patients (5.4%) suffered postoperative complications, of which 13 cases were acute subdural hematoma caused by incomplete hemostasis of the scalp wound and four cases were tension pneumocephalus. Careful hemostasis and complete replacement of subdural hematoma by normal saline to prevent influx of air into the subdural space will further improve the surgical outcome for patients with CSDH.

Shaken baby syndrome and the death of Matthew Eappen: a forensic pathologist's response

Subdural hemorrhage, retinal hemorrhage, and cerebral edema have been considered diagnostic for a "shaken infant" since the syndrome was described almost 30 years ago. However, the specificity of these findings has been disputed by defense witnesses in recent U.S. criminal prosecutions. This review examines the scientific basis for the shaken baby syndrome.

Origin of chronic subdural haematoma and relation to traumatic subdural lesions

The origin of chronic subdural haematoma (CSDH) and the pathogenesis of subdural hygroma (SDG) are still controversial issues. These issues and relationships between these traumatic subdural lesions are discussed. The origin of CSDH is usually a SDG, although a few cases are caused by acute subdural haematomas (ASDH). Subdural hygroma is produced by separation of the dura-arachnoid interface, when there is sufficient subdural space. When the brain remains shrunken, the SDG remains unresolved. Any pathologic condition inducing cleavage of tissue within the dural border layer at the dura-arachnoid interface can induce proliferation of dural border cells with production of neomembrane. In-growth of new vessels will follow, especially along the outer membrane, then bleeding from these vessels occurs. These unresolved SDGs become CSDHs by repeated microhaemorrhage from the neomembrane. Although most victims with ASDH underwent surgery or died, some patients could be managed conservatively. Since the ASDH is usually absorbed within a few weeks, only a very few ASDHs become CSDHs, when there is a sufficient potential subdural space. Chronic subdural haematoma can arise from ASDH, but more commonly from SDG. Such transformation, or development of a new subdural lesion, is a function of the premorbid status and the dynamics of absorption and expansion.

The "subdural" space: a new look at an outdated concept

This review considers the structure of the meninges, as seen at the electron microscopic level, with particular emphasis on the dura-arachnoid junction and whether a naturally occurring space is found at this interface. The classic view has been that a so-called subdural space is located between the arachnoid and dura and that subdural hematomas or hygromas are the result of blood or cerebrospinal fluid accumulating in this (preexisting) space. The dura is composed of elongated, flattened fibroblasts and copious amounts of extracellular collagen. A specialized layer of fibroblasts, the dural border cell layer, is found at the dura-arachnoid junction and is characterized by flattened fibroblasts, no extracellular collagen, extracellular spaces, and few cell junctions. These features combine to create a layer of the inner dura that is structurally weak when compared with external portions of the dura and the internally located arachnoid. The arachnoid layer is composed of larger cells with numerous cell junctions, no extracellular space, and no extracellular collagen. The occurrence of many tight junctions in this layer also serves as a barrier to the movement of fluids and ions. Fibroblasts specialized to form the arachnoid trabeculae attach to the inner surface of the arachnoid layer, bridge the subarachnoid space, and surround vessels in the subarachnoid space as well as attach to pia on the surface of the brain. Under normal conditions, there is no evidence of a naturally occurring space being extant at the dura-arachnoid junction. A space may appear at this point subsequent to pathological/traumatic processes that result in tissue damage with a cleaving opening of the structurally weakest plane in the meninges--through the dural border cell layer. Furthermore, when a space does appear, it is not "subdural" in location but rather within a morphologically distinct cell layer.

Changes in CSF pressures during experimental acute arterial subdural bleeding in pig

The effects of acute arterial subdural bleeding on cerebrospinal fluid (CSF) pressure and 12 other vital parameters were studied in spontaneously breathing pigs (group 1, n = 9) and in mechanically ventilated pigs (group 2, n = 18) to analyze quantitatively the bleeding course and the lethal mechanism. Spontaneously breathing animals all succumbed after a mean bleeding volume of 45.6 +/- 8.9 ml, corresponding to about 50 per cent of the intracranial volume, and a mean bleeding duration of 11.0 +/- 2.6 min. Rapid rise in CSF pressures, marked transtentorial pressure gradients, and progressive reductions of cerebral perfusion pressure leading to a permanently iso-electric EEG, apnoea and to a terminal rise in arterial pressure (Cushing response), was the rule in these animals. The mechanically ventilated animals had smaller bleeding volumes (34.3 +/- 8.1 ml), but longer bleeding durations (13.8 +/- 5.8 min). In this group 7 animals survived. They had no pressure gradients, and only moderate changes in arterial pressure and EEG. The 11 animals that succumbed had marked transtentorial pressure gradients, but smaller increments in arterial pressure than the spontaneously breathing animals. At autopsy, subdurally located blood was found throughout the intracranial and spinal subdural compartments and along the spinal nerve roots in both groups. The results of this study suggest that survival after acute subdural haematoma is influenced by the presence of transtentorial pressure gradients and by the spinal sac acting as a space for expansion. The beneficial effect of artificial ventilation is discussed.

The subdural space interpreted as a cellular layer of meninges

The subdural region within the cranial meninges is examined in guinea pigs by electron microscopy. The fine structures of the arachnoid membrane and dura are described separately in specimens that have been isolated from each other during removal from the cranial cavity. In addition, the fine structure of the intact dura-arachnoid is described, where the subdural space would be present in an undisrupted state. Lastly, the inner surface of the dura and the outer surface of the arachnoid membrane are examined at the point of separation between the two specimens where the dura is reflected from the arachnoid by experimental dissection. From these observations morphologic criteria are established for identifying the constituents and boundaries of the subdural space and for explaining mechanisms in the histogenetic process of "opening" or enlarging this space. The morphologic identity of the classic subdural space is reinterpreted in light of the findings. The subdural space, traditionally described as a fluid-filled potential cavity existing in an extracellular compartment, is not apparent in the guinea pig. Instead, fragile cells designated as light cells occupy the compartment between the dura and arachnoid, with very little extracellular space available. Experimental opening of the subdural space occurs, significantly, along pathways extending by fracture through the cytoplasm and intercellular separation of these light cells rather than by enlargement of a preexisting mesothelial-lined intercellular space between these cells and the true arachnoid cells. Cytoplasmic fine structure of light cells suggests a close kinship with cells in the meningeal layer of the dura. The functional significance of the light cells and their possible role in subdural hematomas is discussed.

Subdural compartment in pig: a morphologic study with blood and horseradish peroxidase infused subdurally

The dura-arachnoid junction is examined in normal animals and in animals subjected to subdural infusion of blood immediately prior to death, simulating acute subdural hemorrhages. The Norwegian landrace pig is used as the experimental animal. Horseradish peroxidase (HRP) has been added to the injected blood to serve as a macromolecular tracer. The material is studied by light and electron microscopy. Special attention is given to the level of the induced subdural cleavage plane, the total distribution of the infused blood, and the natural sites of drainage. The dura-arachnoid junction, identified here as the subdural compartment (the dural border layer of others), consists of an avascular tissue with flake-like, relatively electron-lucent cells stacked upon each other in several layers with narrow intercellular clefts. Under normal conditions there is no evidence of a so-called "subdural space." When under the present experimental conditions bleeding takes place into this cellular tissue, it splits without any particular, predestined cleavage plane, although most often close to the fibrous matter of the dura. The bleeding extends throughout the cerebral and spinal parts of the compartment and also along the spinal nerve roots. Contamination of the subarachnoid space occurs only in some cases subjected to large infusions and apparently only at spinal levels. The HRP diffuses into the dura, but does not traverse the arachnoid barrier layer.

Symptomatic subacute subdural haematoma following spontaneous acute subdural haematoma

Two patients with non-traumatic acute subdural haematoma were observed, initially without surgical intervention. Eleven days after the onset, each patient developed hemiparesis and an increase in severity of headache. Serial computed tomography scans demonstrated that the initial hyperdense haematomas became hypodense with a definite increase in volume. The term "symptomatic subacute subdural haematoma" was proposed to properly define this pathological process, which necessitated removal of the haematoma in the subacute stage. The mechanism of increase in the volume of the haematoma is discussed.

Features of chronic subdural haematoma developed from definitely identified acute subdural haematoma

Follow-up results for 13 cases of acute subdural haematoma, which were identified by CT scan within two days of head injury and treated conservatively, were classified into two groups: In the first group of seven cases the acute subdural haematoma disappeared spontaneously within two weeks; in the second group the other six cases revealed clinical signs and CT scan findings which were identical to chronic subdural haematoma and underwent surgery within three weeks after the head injury. This group showed low ICP signs, such as the chronic stage of cerebral thrombosis, atrophic brain or subdural fluid collection with acute subdural haematoma at the initial CT scan, and most of these cases had only minor head injury. Common features of the operative findings in this second group, in which chronic subdural haematoma developed, included the identification of an external haematoma capsule based on the fibrin layer and granulation tissue beneath the dura. Also, fluid type haematoma was present under these structures, but no inner membrane of the haematoma could be identified other than the non-transparent white arachnoid membrane. Our results indicate the importance of a low ICP in determining whether or not acute subdural haematoma progresses to chronic subdural haematoma.

Experimental chronic subdural hematoma in mice. Gross morphology and light microscopic observations

A new experimental model of chronic subdural hematoma in mice is described. A single intraperitoneal injection of 6-aminonicotinamide (25 mg/kg body weight) on the 5th postnatal day induced hydrocephalus in mice with almost 100% success. Approximately 60% of the mice spontaneously developed intracranial hemorrhage 20 days after the injection. About 1 week after the hemorrhage, a lens-shaped or spherical subdural hematoma was observed, accompanied by marked dilatation of the lateral ventricles and intraventricular hemorrhage. Histological examination revealed that the hematoma contained well-organized outer and inner membranes. Fresh hemorrhage surrounded by many hemosiderin-laden macrophages was seen at the margin of the hematoma adjacent to the organizing outer membrane, in which many fibroblasts and blood vessels were noted. The inner membrane of the hematoma was made up of several tiers of flattened cells with thin-walled blood vessels. The gross morphology and histology of these hematomas closely resembled those of human chronic subdural hematoma.

Subdural fluid collection following craniotomy

The occurrence of subdural fluid collection following craniotomy for intracranial aneurysms was studied with regard to the patient's age, preoperative grade, external decompression, incidence of the craniotomy, external drainage, and ventriculoperitoneal shunt. The following results and conclusions were obtained: Enlargement of the subdural space was observed in 76 of 147 patients (51.7%). The patient's age was the most likely causative factor in producing the lesion. Six patients required surgical management for the collection: three were for subdural hygroma and three were for chronic subdural hematoma. It is estimated that two factors, multiple craniotomy and younger age, accelerated the formation of symptomatic subdural hygromas. When the patient complains of headache or motor weakness 1 or 2 months after undergoing a craniotomy, one should suspect chronic subdural hematoma, especially in an elderly patient with ruptured aneurysm.

Fluid chronic epidural haematoma: a rare complication of ventriculo-peritoneal shunt

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The role of endothelial gap junctions in the enlargement of chronic subdural hematomas

The structure of macrocapillaries (also called 'sinusoids") in the outer membrane of chronic subdural hematomas was investigated by electron microscopy, with particular attention paid to vascular permeability. One characteristic of macrocapillaries is the frequent formation of gap junctions between adjacent endothelial cells. In endothelial gap junctions 0.6 to 8 microns in diameter, numerous blood components, including red blood cells and plasma, can be seen squeezing or spilling into the interstitial space of the outer membrane. Irregularly deformed erythrocytes are located around the macrocapillaries, and amorphous material is seen among scattered thin collagen fibers. It is suggested that endothelial gap junctions of macrocapillaries play an important role in the leakage of blood, causing enlargement of chronic subdural hematomas.

Chronic subdural hematomas: a review

✓ Present knowledge of the still controversial pathogenetic, ultrastructural, diagnostic, and treatment aspects of chronic subdural hematomas is reviewed.

Presence of smooth-muscle cells in the subdural neomembrane

The authors encountered a case of chronic subdural hematoma of which the subdural neomembrane (SN) showed numerous spindle-shaped cells identified as smooth-muscle cells (SMC's) by electron microscopy. On reexamination of 214 cases from the files, SMC's were found with light microscopy in seven cases. In these cases, the SN was well organized (collagenized). In three additional cases examined with both light and electron microscopy, SMC's were not apparent with light microscopy. However, in all cases, cells with ultrastructural features of both fibroblasts and SMC's were observed. Well formed SMC's were found in two additional cases of well organized membrane. Based on these observations, it is concluded that the presence of SMC's in the SN is not a rare phenomenon. The possible origin of SMC's in the SN and their pathological significance to the organizing process of chronic subdural hematoma are discussed.

Definitive treatment of chronic subdural hematoma by twist-drill craniostomy and closed-system drainage

A simple method of bedside twist-drill craniostomy and closed-system drainage for evacuation of chronic and subactue subdural hematoma is introduced. The principles and theoretical considerations that form the basis for this technique are discussed. The technique was used in 21 patients with chronic or subacute subdural hematoma; it has produced results superior to those of the conventional methods used in our patient population. Possible mechanism responsible for the better results with the simple twist-drill closed-system drainage are described.

Physiopathogenesis of subdural hematomas. Part 1: Histological and biochemical comparisons of subcutaneous hematoma in rats with subdural hematoma in man

The dorsal subcutaneous injection in rats of 12 ml or more of autologous hemolyzed whole blood clotted in situ induced the formation of sterile, hemispheric lesions, 47% of which showed an initial decrease in volume followed by a progressive enlargement. The behavior, histology, and biochemical characteristics of the liquid contents of these lesions were found to be remarkably similar to those of subdural hematomas in man. To evaluate the role of the various blood components that may have influenced the formation and growth of these lesions, more than 150 clots composed of human platelet-free plasma, autologous hemolyzed blood, or autologous whole blood were implanted subcutaneously in rats by either surgical or injection techniques. The in vitro behavior of the different clots used was also assessed. This systematic approach led to the following conclusions: 1) the composition and volumes of the clots are critical variables; 2) plasma-fibrin provides the matrix shape of the lesions; 3) the breakdown products derived from erythrocytes, hemoglobin, leukocytes, and other solid blood elements induce neomembrane formation and contribute to the lesion's subsequent growth; and 4) inflammation mechanisms appear to be essential, while cerebrospinal fluid plays no discernable role in this process.

Chronic subdural hematoma: concepts of physiopathogenesis. A review

From the present review it seems clear that the physiopathogenesis of the chronic subdural hematoma is far from being completely understood. However, an analysis of the known data can be summarized as follows: The development of subdural hematomas most likely occurs following minimal trauma in those patients with predisposing factors. Experimental data substantiates the fact that an accumulation of clotted blood in the subdural or subcutaneous space induced the formation of the fibroplastic neomembrane. The hypothesis that blood must come in contact with cerebrospinal fluid in order for the growth to occur, is still controversial. It has been virtually disproven that osmosis, referring to the electrolyte gradient as measured by freezing point depression, has any significance as a growth inducing factor. The protein oncotic gradient theory, having been the most widely accepted explanation as to the progressive enlargement of the subdural hematoma sac, has little experimental data supporting it. A larger body of clinical evidence exists supporting the concept that plasma and/or erythrocytes continuously penetrate into the subdural cavity, where enhanced fibrinolytic activity is present. However, this chronic rebleeding cannot fully explain the observed growth, because the composition of the hematoma fluid is smoewhat different from serum or plasma, and the protein content is also progressively diluted by fluid arising from an unknown source. There is some clinical and experimental evidence to suggest that a production-reabsorption balance may be a significant growth variable. No work has been done to define the role, if any, of local inflammatory mechanisms in the chronic subdural hematoma. Sound clinical evidence has shown that after the initial formation of the subdural clot, growth follows, than a slow, complete reabsorption usually occurs. Aside from the plausible production-reabsorption balance concept, it is not known why the evolution proceeds in this manner.