Subdural Hygroma After Management of Ruptured Intracranial Aneurysms: Incidence, Associated Factors, Clinical Course, and Management Options.

OBJECTIVE: To evaluate the incidence, associated factors, clinical course, and management options of subdural hygroma in patients treated for aneurysmal subarachnoid hemorrhage (aSAH). METHODS: From January 2013 until June 2022, 336 consecutive patients with aSAH underwent treatment in our center. No one patient was excluded from the study cohort. Computed tomography (CT) examinations were performed at admission, immediately after surgery and on the first postoperative day, and subsequently in case of any neurologic deterioration or, at least, once per week until discharge from the hospital. Thereafter, CT examinations were at the discretion of specialists in the rehabilitation facility, referring physicians, or neurosurgeons at the outpatient clinic. RESULTS: The length of radiologic follow-up starting from CT at admission ranged from 1 to 3286 days (mean, 673 ± 895 days; median, 150 days). Subdural hygromas developed in 84 patients (25%). An average interval until this imaging finding from the initial CT examination was 25 ± 55 days (median, 8 days; range, 0-362 days). Evaluation in the multivariate model showed that patient age ≥72 years (P < 0.0001), cerebrospinal fluid (CSF) shunting (P < 0.0001), and microsurgical clipping of ruptured intracranial aneurysm (RIA; P < 0.0001) are independently associated with the development of subdural hygroma. In 54 of 84 cases (64%), subdural hygromas required observation only. Increase of the lesion size with (5 cases) or without (10 cases) appearance of midline shift was associated with patient age <72 years (P = 0.0398), decompressive craniotomy (P = 0.0192), and CSF shunting (P = 0.0009), whereas evaluation of these factors in the multivariate model confirmed independent association of only CSF shunting (P = 0.0003). Active management of subdural hygromas included adjustment of the shunt programmable valve opening pressure, cranioplasty, external subdural drainage, or their combination. Overall, during follow-up (mean, 531 ± 824 days; median, 119 days; range, 2-3285 days) after the start of observation or applied treatment, subdural hygromas showed either decrease (50 cases) or stabilization (34 cases) of their sizes, and no one lesion showed progression again. CONCLUSIONS: The clinical course of subdural hygromas in patients treated for aSAH is generally favorable, but occasionally these lesions show progressive enlargement with or without the appearance of midline shift, which requires active management.

Subdural fluid collection rather than meningitis contributes to hydrocephalus after cervical laminoplasty: A case report.

BACKGROUND: Hydrocephalus following dural tear after spinal surgery is rare. Although a few cases of obstructive hydrocephalus caused by subdural fluid collection and communicating hydrocephalus associated with meningitis have been reported, the mechanism remains uncertain. Herein we describe a patient complicated with hydrocephalus after cervical laminoplasty in whom subdural fluid collection in the cervical spine and posterior cranial fossa rather than chronic meningitis was the main mechanism. CASE SUMMARY: A 45-year-old man underwent cervical laminoplasty for cervical spondylotic myelopathy at a local hospital. Ten days postoperatively, a high fever occurred and magnetic resonance imaging (MRI) showed cerebrospinal fluid (CSF) leakage. Pseudomeningocele liquid test showed high levels of protein and white blood cell (WBC) count with negative bacterial culture. The patient was treated with short-term intravenous antibiotic and discharged with normal body temperature. The patient was uneventful during the first 8 mo follow-up although repeated MRI showed persistent pseudomeningocele. At the 9th mo postoperatively, the patient gradually presented with dizziness and headache accompanied by recurrent weakness of his left arm. Imaging examinations demonstrated hydrocephalus and a cystic lesion around the cervical spinal cord. CSF test from lumbar puncture indicated chronic meningitis. MRI on 1 d after pseudomeningocele drainage showed a significant decrease in the cystic volume, suggesting that the cystic lesion would be subdural fluid collection rather than adhesive arachnoiditis. After dural defect repair, the patient's symptoms completely resolved and hydrocephalus gradually disappeared. CSF analysis at the 21-mo follow-up revealed significantly decreased protein level and WBC count. CONCLUSION: Subdural fluid collection rather than meningitis contributes to the hydrocephalus formation after cervical laminoplasty.

Immediate postoperative MRI findings after lumbar decompression surgery: Correlation of imaging features with clinical outcome.

An understanding of the common MRI findings observed after decompression surgery is important. However, to date, no study addressing this has been published. The aim of this study was to analyze and describe the immediate postoperative MRI findings after lumbar decompression surgery. We retrospectively analyzed the immediate postoperative MRIs of 121 consecutive patients who underwent lumbar decompression surgery between July 2017 and June 2018. Changes in stenosis at the decompressed and adjacent levels, epidural fat edema, epidural and subdural fluid collections, nerve root swelling, facet joint effusions, intervertebral disc signal, and paravertebral muscle edema were correlated with clinical characteristics. Both groups had reduced central canal stenosis postoperatively (p < 0.001) but worsened stenosis at adjacent segments. Fluid collection, hemorrhagic or non-hemorrhagic, at the laminectomy site was the commonest finding (one-level: 73.8%, two-level: 88.5%), with a higher percentage of severe central canal compromise in the two-level decompression group (p = 0.003). Other postoperative MRI findings, such as epidural fat edema, nerve root swelling, subdural fluid collection, and facet joint effusion, were noted without statistical significance. In conclusion, even with successful decompression for lumbar canal stenosis, increased central canal stenosis at adjacent segments is common on immediate postoperative MRI scans, showing no statistically significant correlation with the immediate postoperative outcome. Postoperative fluid collection at the laminectomy site is the commonest imaging finding, and higher rates of hemorrhagic fluid and more severe central canal compromise occur in two-level decompression, but rarely cause clinical problems.

Bilateral arachnoid cyst-associated subdural fluid collections in an infant following TBI.

INTRODUCTION: arachnoid cyst-associated subdural fluid collections have been documented in children and adults following traumatic brain injury (TBI). However, this phenomenon has not been previously demonstrated in infants less than 12 months of age. We present a case of an infant with bilateral arachnoid cyst-associated subdural fluid collections identified after TBI. CASE PRESENTATION: a 9-month-old female infant with profound macrocephaly presented to medical care with altered mental status following a witnessed fall down steps while unsecured in a stroller. Neuroimaging revealed bilateral subdural fluid collections, in addition to a hyperdense subdural hematoma, that raised concern for abusive head trauma (AHT) among the pediatric inpatient team and the hospital's Suspected Child Abuse and Neglect (SCAN) Team was consulted. After excluding occult abusive injuries as well as testing for underlying medical conditions, the infant's bilateral subdural fluid collections were attributed to rupture of a pre-existing left middle cranial fossa arachnoid cyst with evidence of prior macrocephaly. CONCLUSION: In infants and toddlers, the identification of subdural fluid collections on neuroimaging warrants inclusion of AHT in the differential diagnosis. However, in infants with a history of congenital macrocephaly, and an otherwise negative AHT workup, an accidental mechanism for the formation of subdural collections should be considered, especially when co-occurring with an arachnoid cyst.

Spontaneous Resolution of Late-Onset, Symptomatic Fluid Collection Localized in the Meningioma Resection Cavity: A Case Report and Suggestion of Possible Pathogenesis.

Postoperative complications after brain tumor surgery occur occasionally and it is important for clinicians to know how to properly manage each complication. Here, we described a rare case of late-onset, subdural fluid collection localized at the resection cavity that caused motor weakness after convexity meningioma resection, requiring differentiation from an abscess, to help clinicians determine treatment strategies. A 58-year-old right-handed female was admitted to the hospital with a headache and posterior neck pain. Brain computed tomography (CT) scans and magnetic resonance (MR) images showed a homogeneously enhanced, calcified, and multi-lobulated mass adjacent to the right motor strip without perilesional edema. The patient underwent surgery without incident or residual deficit and was discharged from the hospital in good condition. Six weeks after surgery, the patient complained of left arm monoparesis without infection-related symptoms. Brain imaging studies showed a localized fluid collection in the resection cavity with an enhanced margin and perilesional edema. Diffusion restriction was not detected. After three months of conservative treatment without surgery or antibiotics, she recovered from the neurologic deficits, and brain imaging studies showed the spontaneous regression of the fluid collection and perilesional edema. Late-onset, localized fluid collection at the resection cavity, which is similar to an abscess, could occur three to eight weeks after meningioma resection. When there are predisposing factors, including blood components and hemostatic materials in the surgical cavity, it is important for clinicians to understand this type of complication and choose conservative management as a feasible strategy.

Diaphragmatic palsy in a 10-month-old boy with infantile tremor syndrome causing respiratory failure with full response to vitamin B12 therapy.

Infantile tremor syndrome (ITS) owing to vitamin B12 deficiency usually presents with tremors, anaemia, pigmentary skin changes, neuro-regression and hypotonia. A 10-month-old boy with ITS and respiratory failure owing to bilateral diaphragmatic palsy who responded to high parenteral doses of vitamin B12 is presented. As far as we are aware, this is the first report of diaphragmatic palsy associated with ITS and vitamin B12 deficiency.

Modified Arachnoid Plasty Reduces Chronic Subdural Hematoma after Unruptured Aneurysm Clipping : Technical Note.

OBJECTIVE: Chronic subdural hematoma (CSDH) is a rare complication of unruptured intracranial aneurysm (UIA) clipping surgery. To prevent postoperative CSDH by reducing subdural fluid collection, we applied the modified arachnoid plasty (MAP) during the UIA clipping surgery to seal the dissected arachnoid plane. METHODS: This retrospective study included 286 patients enrolled from July 2012 to May 2015. We performed arachnoid plasty in all patients, with MAP used after June 17, 2014. Patients were divided into two groups (non-MAP vs. MAP), and by using uni- and multivariate analyses, baseline characteristics, and relationships with postoperative CSDH between the two groups were analyzed. The degree of preoperative brain atrophy was estimated using the bicaudate ratio (BCR) index. RESULTS: Ten patients (3.5%) among 286 patients had postoperative CSDH after clipping. Nine (3.1%) were in the non-MAP group, and one (0.9%) was in the MAP group. The higher BCR index showed statistical significance with occurrence of postoperative CSDH in both uni- (p=0.018) and multivariate (p=0.012, odds ratio [OR] 8.547, 95% confidence interval [CI] 1.616-45.455) analyses. MAP was associated with a lower risk of postoperative CSDH (p=0.022, OR 0.068, 95% CI 0.007-0.683). CONCLUSION: This study shows that the degree of preoperative brain atrophy is associated with an increased occurrence of CSDH after clipping and that MAP could help reduce the risk of postoperative CSDH after unruptured aneurysm clipping via a lateral supraorbital approach.

Central Herniation Induced by Craniotomy Prompting Air Replacement for Subdural Fluid Collection Due to Cerebrospinal Fluid Hypovolemia.

BACKGROUND: Chronic subdural hematoma (CSDH) often occurs in association with cerebrospinal fluid (CSF) hypovolemia. Many cases with CSDH due to CSF hypovolemia and treated by burr hole surgery have been reported to present with paradoxical deterioration. However, the mechanisms and pathology of deterioration after surgery for CSDH due to CSF hypovolemia remain obscure. CASE DESCRIPTION: We report herein a 62-year-old man with gait disturbance due to subdural fluid collection (SDFC) who underwent burr hole irrigation and additional craniotomy, in which postoperative deterioration resulted from rapidly progressing central herniation with a large amount of air accumulation. Epidural blood patch with saline infusion in the thoracic spine finally resolved central herniation. CONCLUSION: SDFC deteriorating after surgery has never been reported. SDFC has communication with CSF differing from mature CSDH composed of closed cavity surrounded by neomembrane. Under situations of CSF hypovolemia due to spinal dural tear, opening the cranium can prompt air replacement in the CSF space, which might represent a substantial risk for central herniation caused by a rapid loss of buoyancy force.

Subdural Fluid Collection After the Clipping of Unruptured Intracranial Aneurysms: Its Clinical Course and Significance.

OBJECTIVE: We evaluated the clinical course and significance of postoperative subdural fluid collection (SFC) and identified the patients who were at risk of developing postoperative chronic subdural hematoma (CSDH) after the clipping of unruptured intracranial aneurysms (UIAs). METHODS: Between January 2012 and June 2014, we retrospectively reviewed 298 patients with UIAs treated by microsurgical clipping. Among them, 257 patients were enrolled in the present study. Subdural lesions (SDLs) were defined as SFC at 1-month follow-up computed tomography (CT) and a CSDH at any time within 1 month after the clipping of UIAs. We examined the volume changes, Hounsfield unit (HU) values, and the end results of SFC in serial CT scans. RESULTS: The incidence of postoperative CSDH that needed burr hole surgery was 2.5%. Changes in SFC volume that occurred within 1 week of surgery were a risk factor for the occurrence of SDL at the 1-month follow-up CT (odds ratio 34.039; P < 0.001). The corrected average HU value of SCF (cut-off value: 11.9, with a sensitivity of 83.3% and specificity of 73.7%) on postoperative day 7 was an independent risk factor for development of a CSDH at the 1-month follow-up CT (odds ratio 19.261; P = 0.003). CONCLUSIONS: SDLs seen during 1-month follow-up may be associated with the occurrence of increased SFC volume within a week after the clipping of UIAs. The corrected average HU value of the SFC on postoperative day 7 was the only risk factor for the development of CSDHs at 1-month follow-up CT.

Benign extracerebral fluid collection complicated by subdural hematoma and fluid collection: clinical characteristics and management.

INTRODUCTION: Benign extracerebral fluid collection (bECFC) can be complicated by subdural hematoma (SDH) or subdural fluid collection (SDFC). The etiology, natural history, and management strategy for SDH/SDFC in bECFC are not fully understood. We retrospectively reviewed the cases of bECFC patients complicated with SDH/SDFC and tried (1) to confirm the fact that bECFC children are vulnerable to SDH/SDFC, (2) to investigate the clinical significance of 'trauma history' witnessed by a caregiver, and (3) to determine optimal management for them. METHOD: Among 213 bECFC patients identified from January 2000 to August 2015, 20 patients (male:female = 14:6; median age, 6.5 months; range 1-16 months) complicated by SDH/SDFC documented with brain imaging were evaluated for their clinical manifestations, radiologic features, and management outcomes. The median follow-up period was 9.5 months. They were divided into two groups (traumatic group versus non-traumatic group) according to whether objective radiologic evidence of head injury was present or not, and the two groups were analyzed for any clinical differences between them. We also evaluated the clinical significance of witnessed traumatic events by caregivers as an additional independent variable in the analysis. RESULTS: The incidence of SDH/SDFC in bECFC patients was 9.4% (20/213) in our data. In a comparative analysis, the traumatic group is more likely to have 'acute' stage SDH, whereas the non-traumatic group is more likely to have 'chronic' stage SDH. The trauma history witnessed by caregivers did not show clinical significance in the data analysis when included as an independent variable. The prognosis of SDH/SDFC in bECFC patients was favorable without surgery in most of patients regardless of whether the patient has evidence of head trauma or not. CONCLUSION: Benign ECFC is vulnerable to SDH/SDFC development. For the bECFC patients complicated by SDH/SDFC, the trauma history witnessed by a caregiver did not show any clinical significance. A 'wait and watch' strategy is sufficient for the management of SDH/SDFC in bECFC patients.

Novel Application of Time-Spatial Labeling Inversion Pulse Magnetic Resonance Imaging for Diagnosis of External Hydrocephalus.

BACKGROUND: Although a subdural fluid collection frequently is observed, diagnostic methods that differentiate between the subdural collection caused by external hydrocephalus and that caused by subdural hygroma have not been established. Here, we report a case of external hydrocephalus caused by Gliadel-induced eosinophilic meningitis that has been previously reported in only 1 case and can be diagnosed by time-spatial labeling inversion pulse magnetic resonance imaging (time-SLIP MRI). CASE DESCRIPTION: A tumor located in the left temporal was detected incidentally in an 81-year-old man by examination of a head injury. The tumor was surgically resected and diagnosed as a high-grade glioma during the surgery; Gliadel wafers subsequently were implanted. Three weeks after the resection, the patient showed disturbed consciousness, and computed tomography revealed a subdural fluid collection. The out-flow of cerebrospinal through the resection cavity was detected by time-SLIP MRI. Cerebrospinal tests indicated high white blood cell counts and high protein levels, with more than 90% of the white blood cell count comprising eosinophils. Therefore, we suspected that the subdural fluid collection was caused by external hydrocephalus because of Gliadel-induced eosinophilic meningitis. We surgically removed the Gliadel wafers and subsequently performed a surgery to insert a ventriculoperitoneal shunt. Histologic examination indicated eosinophilic accumulation around the Gliadel wafers. The patient's symptoms improved after the insertion of a ventriculoperitoneal shunt. CONCLUSIONS: In the present case, time-SLIP MRI was a useful and noninvasive method for diagnosing external hydrocephalus which was caused by eosinophilic meningitis because of Gliadel-induced eosinophilic meningitis.

Modified Arachnoid Plasty Reduces Chronic Subdural Hematoma after Unruptured Aneurysm Clipping : Technical Note

OBJECTIVE: Chronic subdural hematoma (CSDH) is a rare complication of unruptured intracranial aneurysm (UIA) clipping surgery. To prevent postoperative CSDH by reducing subdural fluid collection, we applied the modified arachnoid plasty (MAP) during the UIA clipping surgery to seal the dissected arachnoid plane.METHODS: This retrospective study included 286 patients enrolled from July 2012 to May 2015. We performed arachnoid plasty in all patients, with MAP used after June 17, 2014. Patients were divided into two groups (non-MAP vs. MAP), and by using uni- and multivariate analyses, baseline characteristics, and relationships with postoperative CSDH between the two groups were analyzed. The degree of preoperative brain atrophy was estimated using the bicaudate ratio (BCR) index.RESULTS: Ten patients (3.5%) among 286 patients had postoperative CSDH after clipping. Nine (3.1%) were in the non-MAP group, and one (0.9%) was in the MAP group. The higher BCR index showed statistical significance with occurrence of postoperative CSDH in both uni- (p=0.018) and multivariate (p=0.012; odds ratio [OR], 8.547; 95% confidence interval [CI], 1.616–45.455) analyses. MAP was associated with a lower risk of postoperative CSDH (p=0.022; OR, 0.068; 95% CI, 0.007–0.683).CONCLUSION: This study shows that the degree of preoperative brain atrophy is associated with an increased occurrence of CSDH after clipping and that MAP could help reduce the risk of postoperative CSDH after unruptured aneurysm clipping via a lateral supraorbital approach.

Modified Arachnoid Plasty Reduces Chronic Subdural Hematoma after Unruptured Aneurysm Clipping : Technical Note

OBJECTIVE: Chronic subdural hematoma (CSDH) is a rare complication of unruptured intracranial aneurysm (UIA) clipping surgery. To prevent postoperative CSDH by reducing subdural fluid collection, we applied the modified arachnoid plasty (MAP) during the UIA clipping surgery to seal the dissected arachnoid plane. METHODS: This retrospective study included 286 patients enrolled from July 2012 to May 2015. We performed arachnoid plasty in all patients, with MAP used after June 17, 2014. Patients were divided into two groups (non-MAP vs. MAP), and by using uni- and multivariate analyses, baseline characteristics, and relationships with postoperative CSDH between the two groups were analyzed. The degree of preoperative brain atrophy was estimated using the bicaudate ratio (BCR) index. RESULTS: Ten patients (3.5%) among 286 patients had postoperative CSDH after clipping. Nine (3.1%) were in the non-MAP group, and one (0.9%) was in the MAP group. The higher BCR index showed statistical significance with occurrence of postoperative CSDH in both uni- (p=0.018) and multivariate (p=0.012; odds ratio [OR], 8.547; 95% confidence interval [CI], 1.616–45.455) analyses. MAP was associated with a lower risk of postoperative CSDH (p=0.022; OR, 0.068; 95% CI, 0.007–0.683). CONCLUSION: This study shows that the degree of preoperative brain atrophy is associated with an increased occurrence of CSDH after clipping and that MAP could help reduce the risk of postoperative CSDH after unruptured aneurysm clipping via a lateral supraorbital approach.

Efficacy of Arachnoid-Plasty on Chronic Subdural Hematoma Following Surgical Clipping of Unruptured Intracranial Aneurysms.

BACKGROUND: We aimed to elucidate the effects of arachnoid plasty (ARP) on chronic subdural hematoma (CSDH) occurrence following clipping surgery. METHODS: In total 217 patients (ARP, n = 97; non-ARP, n = 120) who had undergone unruptured intracranial aneurysm (UIA) surgical clipping via the pterional approach were retrospectively assessed. Predisposing factors for CSDH development following the surgery were investigated. Thickness and volume of the subdural fluid collection (SDFC) were measured to determine whether ARP affects postoperative SDFC. RESULTS: The occurrence of postoperative CSDH was higher in patients without ARP compared to those with ARP (12.5 vs. 3.1%; P = 0.01). In multivariate analyses, having an SDFC volume ≥15 mL on postoperative day (POD) 8, (odds ratio [OR] = 15.113; range = 3.159-72.290), and male sex (OR = 4.274; range = 1.291-14.148) were identified as independent predictive factors. Having had ARP (OR = 0.228; range = 0.056-0.927) was, as an independent variable, negatively correlated with the occurrence of CSDH (P < 0.05). Moreover, SDFC volume ≥15 ml on POD 8 was significantly less common in the ARP group compared with the non-ARP group (P = 0.03). CONCLUSION: Patients who underwent ARPs developed fewer CSDHs following UIA clipping surgery. The factors that predicted the development of CSDH included male sex, SDFC volume on POD 8, and ARP. In addition, the ARP patients had lower SDFC volumes (<15 mL). These findings suggested that ARP reduced the incidence of CSDHs after surgical clippings in patients with unruptured aneurysms.

The efficacy and safety of burr-hole craniotomy without continuous drainage for chronic subdural hematoma and subdural hygroma in children under 2 years of age.

PURPOSE: Various treatment modalities have been used in the management of chronic subdural hematoma and subdural hygroma (CSDH/SDHy) in children. However, few studies have examined burr-hole craniotomy without continuous drainage in such cases. Here, we retrospectively evaluated the efficacy and safety of burr-hole craniotomy without continuous drainage for CSDH/SDHy in children under 2 years old. We also aimed to determine the predictors of CSDH/SDHy recurrence. METHODS: We conducted a retrospective chart review of 25 children under 2 years old who underwent burr-hole craniotomy without continuous drainage for CSDH/SDHy at a pediatric teaching hospital over a 10-year period. We analyzed the relationship between CSDH/SDHy recurrence and factors such as abusive head trauma, laterality of CSDH/SDHy, and subdural fluid collection type (hematoma or hygroma). RESULTS: CSDH/SDHy recurred in 5 of the 25 patients (20 %), requiring a second operation at an average of 0.92 ± 1.12 months after the initial procedure. The mean follow-up period was 25.1 ± 28.6 months. There were no complications related to either operation. None of the assessed factors were statistically associated with recurrence. CONCLUSIONS: Burr-hole craniotomy without continuous drainage for CSDH/SDHy appears safe in children aged under 2 years and results in a relatively low recurrence rate. No predictors of CSDH/SDHy recurrence were identified. Advantages of this method include avoiding external subdural drainage-related complications. However, burr-hole drainage may be more effective for CSDH, which our data suggests is more likely to recur than SDHy, providing the procedure is performed with specific efforts to reduce complications.

Subdural fluid collection and hydrocephalus following cervical schwannoma resection: hydrocephalus resolution after spinal pseudomeningocele repair: case report.

The authors report the case of a 31-year-old man who developed neck pain and headache 2 months after the uncomplicated resection of a cervical schwannoma. MR imaging revealed infratentorial subdural fluid collections and obstructive hydrocephalus associated with cervical pseudomeningocele. The clinical symptoms, subdural fluid collections, and ventricular dilation resolved after surgical correction of the pseudomeningocele. This report emphasizes that hydrocephalus may be related to disorders of cerebrospinal fluid flow dynamics induced by cervical pseudomeningocele. In these rare cases, both the hydrocephalus and the symptoms are resolved by the simple correction of the pseudomeningocele.

Incidence and risk factors of chronic subdural hematoma after aneurysmal clipping.

OBJECTIVE: Chronic subdural hematoma (CSDH) after aneurysmal clipping is a rare complication, but its incidence and risk factors are not known in detail. We retrospectively reviewed our cases requiring surgery for CSDH after clipping. METHODS: In our hospital, between January 2000 and December 2006, 794 patients (unruptured, 58.0%) underwent clipping surgery for aneurysm of the anterior circulation. We reviewed incidence and risk factors of CSDH after clipping. For the past 2 years, we reviewed all computed tomography scans for 163 unruptured aneurysms, and examined the relationship between an increase of subdural fluid collection (SFC) and development of CSDH. RESULTS: Fifteen patients (1.9%) developed CSDH after clipping, which required evacuation. Among those, 13 had unruptured aneurysms (2.8%), a much higher percentage than for ruptured aneurysms (0.9%). On univariate statistical analysis, risk factors of CSDH were associated with advanced age (P = 0.0005), male gender (P = 0.04), and unruptured aneurysms (P = 0.02). Aneurysmal location was not related to the development of postoperative CSDH. Contralateral CSDH occurred in 3 patients, but no middle cerebral artery aneurysm developed contralateral CSDH. An increase in postoperative SFC during 1 week was a significant risk factor for CSDH (P = 0.001). CONCLUSIONS: In addition to the classic risk factors, this study showed that clipping for unruptured aneurysms carries a higher risk for CSDH compared to ruptured aneurysms. We suggest that an increase of SFC during 1 week postoperatively can be a factor in predicting CSDH after clipping.

The Active Mechanism of Dural Border Layer Cells in the Process of Subdural Fluid Collection Developing into Hematoma / 医学研究杂志

Objective Discuss the active mechanism of dural border layer cells in the process of subdural fluid collection developing into chronic subdural hematoma.Methods Review and analyse literature combined with one special return case whom with subdural fluid collection.Results At the same case,subdural fluid collection at left side did no change during 49 months,and that at right side developed into chronic subdural hematoma in 23rd week,and the latter was absorbed at 62rd week.Conclusion In the process of subdural fluid collection developing into chronic subdural hematoma,dural border layer cells roll on important functions.