Spontaneous intracranial hypotension presenting with bilateral subdural hematoma: Decision-making and treatment strategies.

BACKGROUND: The timing and decision to drain subdural hematoma (SDH) in spontaneous intracranial hypotension (SIH) remains a dilemma. We reviewed our experience of bilateral SDH secondary to SIH, focusing on decision making and treatment strategies. METHODS: We retrospectively reviewed bilateral SDH secondary to SIH between March 2010 and September 2021. Baseline characteristics of patients, diagnosis, radiologic findings, treatments, and clinical outcome were investigated. RESULTS: Fifteen patients (7 men, 8 women) with bilateral SDH secondary to SIH were included in this study. Initially, patients were treated conservatively (4 patients, 26.7 %), with an epidural blood patch (EBP, 3 patients, 20.0 %), and SDH drainage followed by the Trendelenburg position (8 patients, 53.3 %). All 3 patients that were initially treated with EBP required SDH drainage. Of the 8 patients initially treated with SDH drainage via burr hole followed by Trendelenburg position, 7 patients showed sustained improvements without EBP; however, 1 patient needed EBP. Deterioration to coma occurred in 6 out of 15 patients (40.0 %). All 6 deteriorated patients immediately recovered after SDH drainage with Trendelenburg position; 5 achieved sustained improvement without EBP and 1 required EBP. During the follow-up period, 14 out of 15 patients (93.3 %) showed good recovery. CONCLUSIONS: Evacuation of SDH is not always necessary in SIH; however, we did not hesitate to perform hematoma drainage, in deteriorated patients or those with thick hematoma that is associated with significant sagging and cistern effacement. This can prevent irreversible neurologic complications. Moreover, the Trendelenburg position may help to achieve sustained improvement without additional treatment.

Teaching Video NeuroImage: Status Epilepticus Manifesting as Belly Dancing Secondary to Subdural Hematoma.

A 74-year-old man developed involuntary rhythmic contractions of his left abdomen, after drainage of a chronic right frontoparietal subdural hematoma (Figure). These movements had electroencephalographic correlation with periodic lateralized discharges over the right posterior quadrant (Video 1, Figure) and were classified as clonic abdominal seizures. Clonic abdominal seizures are a rare clinical finding in patients with seizure disorders. The symptomatogenic zone most commonly localizes to the contralateral paracentral frontoparietal region.1 Possible etiologies include primary brain tumors, brain metastasis, CNS infections, cortical dysplasia, stroke, and postsurgical complications.1,2 Clonic abdominal seizures are infrequent, but should be suspected in patients with rhythmic and regular contractions of the hemiabdominal wall in the context of a contralateral cerebral structural lesion.

Cerebral sinovenous thrombosis as a cause of subdural hemorrhage in the pediatric population: Is there a correlation?

PURPOSE: Cerebral sinovenous thrombosis is an increasingly recognized cause of stroke in children and neonates. Its true incidence appears to be underestimated. Despite being a rare event, certain studies have found a correlation between subdural hemorrhage and cerebral sinus thrombosis. The literature suggests that spontaneous cerebral sinovenous thrombosis in the pediatric population may lead to the occurrence of a subdural hemorrhage. In this report, we present a case of cerebral venous thrombosis associated with chronic subdural hematoma and review the literature to highlight the importance of these conditions. CASE REPORT: An 11-year-old boy was admitted in the neurosurgery department with headache and a neurological examination without changes. The imaging studies identified a heterogeneous subdural collection in the fronto-temporo-parietal region. The patient underwent surgical drainage of the subdural hematoma, and the procedure was performed without complications. The magnetic resonance and angiography showed an extensive thrombosis of the superior sagittal sinus, extending downward to the occipital sinus and partially to the right transverse sinus. CONCLUSIONS: Appropriate management in the diagnosis and an early treatment of dural sinus thrombosis associated with subdural hemorrhage can reduce the risk of recurrence and improve the clinical outcome.

Subdural hemorrhage in middle cranial fossa arachnoid cysts: a report of two cases at two ends of the spectrum.

Arachnoid cysts are usually asymptomatic, benign lesions commonly occurring in the middle cranial fossa. However, the cysts may rupture in rare cases causing intracystic or subdural hemorrhages with significant mass effect. We report two cases of middle cranial fossa arachnoid cyst with subdural hemorrhage with very different clinical course. The first case presented with significant mass effect with cerebral herniation and had significant neurological morbidity post-surgery. The second case had minimal symptoms and was managed conservatively with offer of elective surgery. The report underscores the importance of prompt diagnosis and appropriate surgical intervention in managing arachnoid cysts with hemorrhage, highlighting the potential for diverse clinical presentations and outcomes.

Retinodural haemorrhage of infancy, abusive head trauma, shaken baby syndrome: The continuing quest for evidence.

The shaken baby syndrome was originally proposed in the 1970s without any formal scientific basis. Once data generated by scientific research was available, the hypothesis became controversial. There developed essentially two sides in the debate. One side claimed that the clinical triad of subdural haemorrhage, retinal haemorrhage, and encephalopathy, or its components, is evidence that an infant has been shaken. The other side stated this is not a scientifically valid proposal and that alternative causes, such as low falls and natural diseases, should be considered. The controversy continues, but the contours have shifted. During the last 15 years, research has shown that the triad is not sufficient to infer shaking or abuse and the shaking hypothesis does not meet the standards of evidence-based medicine. This raises the issue of whether it is fit for either clinical practice or for the courtroom; evidence presented to the courts must be unassailable. WHAT THIS PAPER ADDS: There is insufficient scientific evidence to assume that an infant with the triad of subdural haemorrhage (SDH), retinal haemorrhage, and encephalopathy must have been shaken. Biomechanical and animal studies have failed to support the hypothesis that shaking can cause SDH and retinal haemorrhage. Patterns of retinal haemorrhage cannot distinguish abuse. Retinal haemorrhages are commonly associated with extracerebral fluid collections (including SDH) but not with shaking. Infants can develop SDH, retinal haemorrhage, and encephalopathy from natural diseases and falls as low as 1 foot. The shaking hypothesis and the literature on which it depends do not meet the standards of evidence-based medicine.

Case Report: Hemorrhagic Fever with Renal Syndrome Complicated by Bilateral Subdural Hematoma.

Hemorrhagic fever with renal syndrome (HFRS) is an acute, natural focal disease worldwide. Bilateral subdural hematoma (BSH) is a rare occurrence in patients with HFRS. A 51-year-old man was admitted with fever, headache, lower back pain, and reduced urine volume. The patient was diagnosed with HFRS accompanied by BSH, as evidenced by IgM and IgG antibodies for hantavirus that were positive, and abnormal blood test results and computed tomographic head scan. He recovered and was discharged after symptomatic treatment. Hemorrhagic fever with renal syndrome might present rare clinical manifestations with BSH. The early identification of this condition is crucial to an improved prognosis.

Expanding phenotype heterogeneity of NARS2 by presenting subdural hematoma and parenchymal hemorrhage.

BACKGROUND: NARS2 encodes mitochondrial Asparaginyl-tRNA Synthetase 2, which catalyzes the aminoacylation of tRNA-Asn in the mitochondria. To date, 24 variants have been reported in NARS2 gene in 35 patients. The phenotypic variability of NARS2-associated disorder is broad, ranging from neurodevelopmental disorders to hearing loss. In this study, we report some novel imaging findings in an Iranian patient suffering from epileptic encephalopathy, caused by a previously reported variant, c.500A > G; p.(His167Arg), in NARS2. METHODS: The spectrum of clinical manifestations of two Iranian patients was investigated and genetic analysis was performed by Whole-exome sequencing (WES). Additionally, we also reviewed the literature and summarized the phenotypes of previously reported patients with variants in the NARS2 gene. RESULTS: Here, we present the phenotypic and genetic features of 2 unrelated Iranian infants presented with neurodevelopmental delay, seizures, hearing impairment, feeding problems, elevated serum lactate levels in addition to subdural hematoma and cerebral parenchymal hemorrhage in the brain magnetic resonance imaging (MRI) of one of the patients. Genetic analysis revealed a biallelic missense variant in NARS2: c.500A > G; p.(His167Arg). We described the subdural hematoma and cerebral parenchymal hemorrhage of the brain for the first time. CONCLUSIONS: Our study provides new clinical findings, subdural hematoma, and parenchymal hemorrhage, in NARS2-related disorders. Our findings along with previous studies provide more evidence of the clinical presentation of the disease caused by pathogenic variants in NARS2. Expanding the clinical spectrum increases the diagnostic rate of molecular testing and improves the quality of counseling for at-risk couples.

Bed Rest as a Protective Factor for Subdural Hematoma in Spontaneous Intracranial Hypotension: A Retrospective Study.

BACKGROUND: Subdural hematoma (SDH) is a potentially life-threatening complication in patients with spontaneous intracranial hypotension (SIH). Though bed rest is the basis of conservative treatment, no clear evidence exists regarding the association between bed rest and the later complication of SDH in these patients. OBJECTIVES: This study aimed to evaluate the association between bed rest and SDH development in patients with SIH. STUDY DESIGN: A retrospective study was conducted from March 2013 through December 2019. Four hundred twenty adult patients diagnosed with SIH were enrolled. Clinical presentations and radiographic findings were recorded. The cumulative duration of bed rest in hours was used to measure the bed rest length. The clinical outcomes during follow-up were assessed. METHODS: Categorical data were compared using chi-square tests; continuous data were compared using the Mann-Whitney U test or Kruskal-Wallis test. A backwards stepwise Cox proportional hazard regression model adjusted with confounders which differed between SDH and non-SDH in univariate analysis was used to estimate the risk of cumulative duration of bed rest for SDH. A stratified Cox regression was performed to exclude the effect of the treatment algorithm. RESULTS: Of the 420 patients with SIH, 88 (21%) were in the SDH Group and 332 (79%) were in the non-SDH (NSDH) Group. The cumulative duration of bed rest in hours was a protective factor for SDH in SIH (Hazard Ratio [HR] = 0.997; P < 0.001). A stratified Cox regression analysis showed that the cumulative duration of bed rest remained a protective factor for SDH both in patients who received conservative treatment before admission (HR = 0.997; P < 0.001) and in those who did not (HR = 0.996; P = 0.061). Age (HR = 1.029, 95% CI, 1.009-1.050; P = 0.004) and orthostatic headache (HR = 4.770, 95% 95% CI, 2.177-10.450; P < 0.001) were risk factors for SDH in SIH. The clinical outcomes, including length of hospital stay, epidural blood patch (EBP) therapy, and repeated EBP therapy, were higher in the SDH Group. The revisit rate was similar between the 2 groups. LIMITATIONS: Retrospective studies are susceptible to different radiological procedures and therapeutic strategies. A bed rest score based on a patient's memory is susceptible to recognition and reporting bias. This is a single-center study and the sample size is not large. The validity of the bed rest scale has not been previously evaluated in any other study. CONCLUSIONS: Bed rest was a protective factor for SDH in patients with SIH. With more time and proper treatment, patients with SIH who have an SDH can achieve good prognosis in the long term.

A rare case of prostate cancer initially presented by disseminated intravascular coagulation-related subdural hemorrhage.

BACKGROUND: Disseminated intravascular coagulation (DIC) has been reported in various solid malignancies and is a common coagulation-related complication in prostate cancer. However, DIC has been rarely reported as the initial presentation of prostate cancer. Herein, we reported a patient referring with subdural hemorrhage (SDH) and DIC with an unexplained cause who was later diagnosed with prostate cancer. CASE PRESENTATION: We presented a 68-year-old man who was referred to the hospital with a gradual deterioration of consciousness, dyspnea, and edema in the genitalia and lower limbs. His primary laboratory tests showed elevated prothrombin time (PT) and partial thromboplastin time (PTT) and a decreased fibrinogen level of 47 mg/dL [200-400 mg/dL]. The DIC score was 7, which was suggestive of DIC. Moreover, cranial imaging showed SDH. Further work-up revealed elevated prostate-specific antigen and prostate enlargement with a mass effect on the bladder with a bone lesion, which was suggestive of metastatic prostate cancer. CONCLUSION: This report highlights DIC as a possible initial presentation of an underlying malignancy, as well as the importance of treatment of underlying disease in the management of DIC. A comprehensive and systematic work-up is essential for early diagnosis in patients with DIC to avoid further complications and mortality.

Age predicts likelihood for surgery for pediatric tbi: an analysis of 1745 hospitlizations from a Chinese Children's Hospital.

PURPOSE: We tested the role of age and sex in surgery following pediatric TBI hospitalization. METHODS: Records of 1745 children hospitalized at a pediatric neurotrauma center in China included age, sex, cause of injury, diagnosis of injury, days of hospitalization, in-house rehabilitation, Glasgow Coma Scale score, mortality, 6-month post-discharge Glasgow Outcome Scale score, and surgery intervention. The children were 0-13 years (M= 3.56 years; SD = 3.06), with 47.4% 0-2 years of age. RESULTS: The mortality rate was 1.49%. Logistic regression on 1027 children with epidural hematoma, subdural hematoma, intracerebral hemorrhage, and intraventricular hemorrhage showed that controlling for other variables, the odds for younger children to receive surgery was statistically lower for epidural hematomas (OR = 0.75; 95% CI = 0.68-0.82), subdural hematomas (OR = 0.59; 95% CI = 0.47-0.74), and intraventricular hemorrhage (OR = 0.52; 95% CI = 0.28-0.98). CONCLUSIONS: While severity of TBI and type of TBI were expected predictors for surgery, a younger age also predicted a significantly lower likelihood of surgery in our sample. Sex of the child was unrelated to surgical intervention.

Bilateral sixth nerve palsy with subdural hematoma: a unique presentation of B12 deficiency.

Vitamin B12 is inextricably associated with the development and maintenance of neuronal functions. It is classically associated with subacute combined degeneration and peripheral neuropathy; however, cranial neuropathy is uncommon. We observed the rarest neurological manifestation of B12 deficiency. A 12 months infant had history of lethargy, irritability, anorexia, paleness, vomiting, and neurodevelopmental delay for 2 months. He also developed inattention and altered sleep pattern. His mother noticed bilateral inward rotation of both eyes. On examination, the infant had bilateral lateral rectus palsy. The infant was found to have anemia (7.7g/dL) and severe B12 deficiency (74pg/mL). On MRI, there was cerebral atrophy, subdural hematoma (SDH) and wide cisternal spaces and sulci. On supplementation with cobalamin, he improved clinically though mild restriction of lateral gaze on the left side persists. Follow up MRI showed significant improvement in cerebral atrophy with resolution of SDH. To date, such clinical presentation of B12 deficiency has never been reported. The authors suggest B12 supplementation for at risk population esp at antenatal stage and lactating mothers in national programs. The treatment of this condition should be initiated early to prevent long term sequelae.

Short Falls in Childhood Occasionally Cause Major Brain Injuries Because of Unusual Circumstances.

METHODS: Records and imaging were reviewed for children younger than 6 years, hospitalized between 2015 and 2020 for major closed head injuries following less than 4-ft falls. Major injury was defined as intensive care admission more than 2 days, neurosurgical intervention, death, or disability at hospital discharge. Subjects were identified through Seattle and Spokane, Washington abuse consultations. Harborview Medical Center's trauma registry and Seattle Children's Hospital's Hemophilia Treatment Program and Radiology were searched for subjects. RESULTS: We identified 12 young children who sustained major closed head injury due to short falls. Seven developed major space-occupying epidural hemorrhages. One child developed internal hydrocephalus after intraventricular hemorrhage. One child with prior meningomyelocele, Chiari 2 malformation, and ventriculoperitoneal shunt developed shunt decompensation after an acute-on-chronic subdural hemorrhage. One child developed an internal capsule stroke because of a previously undiagnosed calcifying angiopathy. Another child developed space-occupying subdural hemorrhage associated with previously unrecognized platelet pool disorder. Only this child had abuse concerns, which were resolved with his coagulopathy diagnosis. One child had a diastatic skull fracture leading to pseudomeningocele.At Harborview Medical Center, 140 children were seen for short falls in the emergency department or inpatient service. Among the 40 needing intensive care, 4 (12.5%) had major injuries after short falls. Our hemophilia treatment program did not see any children who had sustained major injury following a short fall in a 5½ year period. CONCLUSIONS: Although young children rarely sustain major head injury following short falls, serious head injuries do occasionally occur because of unusual injury mechanisms or preexisting conditions. It is important to fully evaluate these patients to differentiate these unintentional falls from abusive head injury.

Factors that Influence Subdural Hemorrhage Secondary to Intracranial Arachnoid Cysts in Children.

OBJECTIVE: This study aimed to investigate factors that influence subdural haemorrhage (SDH) secondary to intracranial arachnoid cysts (IACs) in children. METHODS: Data of children with unruptured IACs (IAC group) and those with SDH secondary to IACs (IAC-SDH group) were analyzed. Nine factors, sex, age, birth type (vaginal or caesarean), symptoms, side (left, right, or midline), location (temporal or nontemporal), image type (I, II, or III), volume, and maximal diameter, were selected. IACs were classified as types I, II, and III according to their morphological changes observed on computed tomography images. RESULTS: There were 117 boys (74.5%) and 40 girls (25.5%); 144 (91.7%) patients comprised the IAC group and 13 (8.3%) comprised the IAC-SDH group. There were 85 (53.8%) IACs on the left side, 53 (33.5%) on the right side, 20 (12.7%) in the midline region, and 91 (58.0%) in the temporal region. The univariate analysis showed significant differences in age, birth type, symptoms, cyst location, cyst volume, and cyst maximal diameter (P < 0.05) between the 2 groups. Logistic regression using the synthetic minority oversampling technique model showed that image type III and birth type were independent factors that influenced SDH secondary to IACs (ß0 = 4.143; ß for image type = -3.979; ß for birth type = -2.542) and that the representative area under the receiver-operating characteristic curve value was 0.948 (95% confidence interval, 0.898-0.997). CONCLUSIONS: IACs are more common in boys than in girls. They can be divided into 3 groups according to their morphological changes on computed tomography images. Image type III and caesarean delivery were independent factors that influenced SDH secondary to IACs.

Long-term outcomes after traumatic brain injury in elderly patients on antithrombotic therapy.

INTRODUCTION: Elderly patients receiving antithrombotic treatment have a significantly higher risk of developing an intracranial hemorrhage when suffering traumatic brain injury (TBI), potentially contributing to higher mortality rates and worse functional outcomes. It is unclear whether different antithrombotic drugs carry a similar risk. OBJECTIVE: This study aims to investigate injury patterns and long-term outcomes after TBI in elderly patients treated with antithrombotic drugs. METHODS: The clinical records of 2999 patients ≥ 65 years old admitted to the University Hospitals Leuven (Belgium) between 1999 and 2019 with a diagnosis of TBI, spanning all injury severities, were manually screened. RESULTS: A total of 1443 patients who had not experienced a cerebrovascular accident prior to TBI nor presented with a chronic subdural hematoma at admission were included in the analysis. Relevant clinical information, including medication use and coagulation lab tests, was manually registered and statistically analyzed using Python and R. In the overall cohort, 418 (29.0%) of the patients were treated with acetylsalicylic acid before TBI, 58 (4.0%) with vitamin K antagonists (VKA), 14 (1.0%) with a different antithrombotic drug, and 953 (66.0%) did not receive any antithrombotic treatment. The median age was 81 years (IQR = 11). The most common cause of TBI was a fall accident (79.4% of the cases), and 35.7% of the cases were classified as mild TBI. Patients treated with vitamin K antagonists had the highest rate of subdural hematomas (44.8%) (p = 0.02), hospitalization (98.3%, p = 0.03), intensive care unit admissions (41.4%, p < 0.01), and mortality within 30 days post-TBI (22.4%, p < 0.01). The number of patients treated with adenosine diphosphate (ADP) receptor antagonists and direct oral anticoagulants (DOACs) was too low to draw conclusions about the risks associated with these antithrombotic drugs. CONCLUSION: In a large cohort of elderly patients, treatment with VKA prior to TBI was associated with a higher rate of acute subdural hematoma and a worse outcome, compared with other patients. However, intake of low dose aspirin prior to TBI did not have such effects. Therefore, the choice of antithrombotic treatment in elderly patients is of utmost importance with respect to risks associated with TBI, and patients should be counselled accordingly. Future studies will determine whether the shift towards DOACs is mitigating the poor outcomes associated with VKA after TBI.

Risk factors, management, and outcomes in isolated parafalcine or tentorial subdural hematomas.

INTRODUCTION: Indications for hospitalization in patients with parafalcine or tentorial subdural hematomas (SDH) remain unclear. This study derived and validated a clinical decision rule to identify patients at low risk for complications such that hospitalization can be avoided. METHODS: A multicenter retrospective medical record review of adult patients with parafalcine or tentorial SDHs was completed. The primary outcome was significant injury, defined as injury that led to neurosurgery, discharge to another facility, or death. A multivariable logistic regression was performed to identify variables independently associated with the outcome in the derivation cohort. These variables were then validated on a separate cohort from a different institution abstracted without knowledge of the identified variables. RESULTS: In the derivation cohort, 134 patients with parafalcine/tentorial SDHs were identified. The mean age was 63 ± 19 years with 82 (61%) male. Seventy-one (53%) had significant injuries. Variables independently associated with significant injury included: age over 60, adjusted odds ratio (aOR) 3.46 (95% CI 1.24, 9.62), initial Glasgow Coma Scale score below 15, aOR =7.92 (95% CI 2.78, 22.5), and additional traumatic brain injuries (TBIs) on computerized tomography (CT), aOR =5.97 (95% CI 2.48, 14.4). These three variables had a sensitivity of 71/71 (100%, 95% CI 96, 100%) and specificity of 12/63 (19%, 95% CI 10, 31%). The validation cohort (n = 83) had a mean age of 62 ± 22 years with 50 (60%) male. The three variables had a sensitivity of 36/36 (100%, 95% CI 92, 100%) and specificity of 7/47 (15%, 95% CI 6.2, 28%). All 39 (100%, 95% CI 93, 100%) patients from both cohorts who underwent neurosurgery had additional TBI findings on their CT scan. CONCLUSIONS: Patients with parafalcine/tentorial SDHs who are under 60 years with initial GCS scores of 15 and no addition TBIs on CT are at low risk and may not need hospitalization. Furthermore, patients with isolated parafalcine/tentorial SDHs are unlikely to undergo neurosurgery. Prospective, external validation with a larger sample size is now recommended. STUDY TYPE: Retrospective Cohort Study.

Systematic Review of Meningiomas Revealed by Spontaneous Intracranial Hemorrhage: Clinicopathological Features, Outcomes, and Rebleeding Rate.

BACKGROUND: Meningiomas are rarely revealed by an intracranial hemorrhage (ICH). Rebleeding occurrence rate and time of onset are unknown. Here, we performed a systematic review of the literature of meningiomas revealed by ICH. METHODS: We retrospectively collected all meningiomas revealed by spontaneous ICH published between January 1980 and December 2021. We reported clinicopathological features of meningiomas revealed by ICH. We also estimated rebleeding rate and time to onset. RESULTS: Ninety-two studies met all inclusion criteria, led to a total of 120 cases. The mean age was 56.3 years, with 66 (55%) female. Seventy-nine (66%) cases were conscious before surgery, 20 (17%) were in coma, and 17 (14%) were unconscious after deterioration. The most frequent bleeding type was subdural hemorrhage (N = 49, 41%) followed by intraparenchymal hemorrhage (IPH) (N = 44, 37%), subarachnoid hemorrhage (SAH) (N = 22, 18%), and intraventricular hemorrhage (IVH) (N = 5, 4%). IPH and hindbrain/ventricular locations are associated with poor outcomes (P = 0.031 and < 0.001, respectively). Among the 19 patients who did not undergo surgical resection of the meningioma, 14 (74%) experienced rebleeding with a median occurrence of 120 days (interquartile, [90; -]). Rebleeding occurs earlier if the type of bleeding is SAH or IVH and for hindbrain location (both P < 0.01). CONCLUSIONS: ICH is a rare presentation of meningiomas. Hindbrain and ventricular tumor location and IPH are associated with poor outcomes. Rebleeding rate is high and premature. It occurs earlier if the first bleeding was SAH or IVH and for hindbrain location.

Mortality Reduction of Acute Surgery in Traumatic Acute Subdural Hematoma since the 19th Century: Systematic Review and Meta-Analysis with Dramatic Effect: Is Surgery the Obvious Parachute?

The rationale of performing surgery for acute subdural hematoma (ASDH) to reduce mortality is often compared with the self-evident effectiveness of a parachute when skydiving. Nevertheless, it is of clinical relevance to estimate the magnitude of the effectiveness of surgery. The aim of this study is to determine whether surgery reduces mortality in traumatic ASDH compared with initial conservative treatment. A systematic search was performed in the databases IndexCAT, PubMed, Embase, Web of Science, Cochrane library, CENTRAL, Academic Search Premier, Google Scholar, ScienceDirect, and CINAHL for studies investigating ASDH treated conservatively and surgically, without restriction to publication date, describing the mortality. Cohort studies or trials with at least five patients with ASDH, clearly describing surgical, conservative treatment, or both, with the mortality at discharge, reported in English or Dutch, were eligible. The search yielded 2025 reports of which 282 were considered for full-text review. After risk of bias assessment, we included 102 studies comprising 12,287 patients. The data were synthesized using meta-analysis of absolute risks; this was conducted in random-effects models, with dramatic effect estimation in subgroups. Overall mortality in surgically treated ASDH is 48% (95% confidence interval [CI] 44-53%). Mortality after surgery for comatose patients (Glasgow Coma Scale ≤8) is 41% (95% CI 31-51%) in contemporary series (after 2000). Mortality after surgery for non-comatose ASDH is 12% (95% CI 4-23%). Conservative treatment is associated with an overall mortality of 35% (95% CI 22-48%) and 81% (95% CI 56-98%) when restricting to comatose patients. The absolute risk reduction is 40% (95% CI 35-45%), with a number needed to treat of 2.5 (95% CI 2.2-2.9) to prevent one death in comatose ASDH. Thus, surgery is effective to reduce mortality among comatose patients with ASDH. The magnitude of the effect is large, although the effect size may not be sufficient to overcome any bias.