Procedimiento anestésico - quirúrgico en un lactante con higrohematoma subdural / Anesthetic - surgical procedure in an infant with subdural hygrohematoma

Se describe el caso clínico de un lactante de 47 días de nacido, quien fue atendido en el Cuerpo de Guardia de Pediatría del Hospital Provincial General Docente Antonio Luaces Iraola de Ciego de Ávila, por presentar aumento de la circunferencia cefálica, irritabilidad y agitación. Los exámenes realizados mostraron signos de hipertensión endocraneana descompensada, secundaria a colección del espacio subdural izquierdo. Se eliminó el higroma subdural y la recuperación fue favorable en las primeras 36 horas; luego comenzó a convulsionar y apareció nuevamente el deterioro neurológico, por lo cual se decidió reintervenir. Se realizó inducción anestésica con tiopental sódico fentanilo y rocuronio. El paciente evolucionó sin complicaciones.

The case report of a 47 days infant is described. He was assisted in the children emergency room of Antonio Luaces Iraola Teaching General Provincial Hospital in Ciego de Ávila, due to an increase of the cephalic circumference, irritability and agitation. The exams showed signs of upset endocranial hypertension, secondary to collection of the left subdural space. The subdural hygroma was eliminated and the recovery was favorable in the first 36 hours; then a covulsion began and the neurological deterioration appeared again, reason why it was decided to operate once more. Anesthetic induction was carried out with fentanyl sodium thiopental and rocuronium. The patient had a favorable clinical course without complications.

Remote Hemorrhage after Burr Hole Drainage of Chronic Subdural Hematoma / 대한신경손상학회지

Chronic subdural hematoma (CSDH) and symptomatic subdural hygroma are common diseases that require neurosurgical management. Burr hole trephination is the most popular surgical treatment for CSDH and subdural hygroma because of a low recurrence rate and low morbidity compared with craniotomy with membranectomy, and twist-drill craniotomy. Many reports suggest that placing a catheter in the subdural space for drainage can further reduce the rate of recurrence; however, complications associated with this type of drainage include acute subdural hematoma, cortical injury, and infection. Remote hemorrhage due to overdrainage of cerebrospinal fluid (CSF) is another possible complication of burr hole trephination with catheter drainage that has rarely been reported. Here, we present 2 cases of remote hemorrhages following burr hole trephination with catheter drainage for the treatment of CSDH and symptomatic subdural hygroma. One patient developed intracerebral hemorrhage and subarachnoid hemorrhage in the contralateral hemisphere, while another patient developed remote hemorrhage 3 days after the procedure due to the sudden drainage of a large amount of subdural fluid over a 24-hour period. These findings suggest that catheter drainage should be carefully monitored to avoid overdrainage of CSF after burr hole trephination.

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.

The Risk Factors for Hydrocephalus and Subdural Hygroma after Decompressive Craniectomy in Head Injured Patients

OBJECTIVE: The present study aims to investigate 1) the risk factors for hydrocephalus and subdural hygroma (SDG) occurring after decompressive craniectomy (DC), and 2) the association between the type of SDG and hydrocephalus. METHODS: We retrospectively reviewed the clinical and radiological features of 92 patients who underwent DC procedures after severe head injuries. The risk factors for developing post-traumatic hydrocephalus (PTH) and SDG were analyzed. Types of SDGs were classified according to location and their relationship with hydrocephalus was investigated. RESULTS: Ultimately, 26.09% (24/92) of these patients developed PTH. In the univariate analyses, hydrocephalus was statically associated with large bone flap diameter, large craniectomy area, bilateral craniectomy, intraventricular hemorrhage, contralateral or interhemisheric SDGs, and delayed cranioplasty. However, in the multivariate analysis, only large craniectomy area (adjusted OR=4.66; p=0.0239) and contralateral SDG (adjusted OR=6.62; p=0.0105) were significant independent risk factors for developing hydrocephalus after DC. The incidence of overall SDGs after DC was 55.43% (51/92). Subgroup analysis results were separated by SDG types. Statistically significant associations between hydrocephalus were found in multivariate analysis in the contralateral (adjusted OR=5.58; p=0.0074) and interhemispheric (adjusted OR=17.63; p=0.0113) types. CONCLUSION: For patients who are subjected to DC following severe head trauma, hydrocephalus is associated with a large craniectomy area and contralateral SDG. For SDGs after DC that occur on the interhemispherical or controlateral side of the craniectomy, careful follow-up monitoring for the potential progression into hydrocephalus is needed.

Arachnoid Membrane Suturing for Prevention of Subdural Fluid Collection in Extracranial-intracranial Bypass Surgery

OBJECTIVE: Water-tight closure of the dura in extracranial-intracranial (EC-IC) bypass is impossible because the superficial temporal artery (STA) must run through the dural defect. Consequently, subdural hygroma and subcutaneous cerebrospinal fluid (CSF) collection frequently occur postoperatively. To reduce these complications, we prospectively performed suturing of the arachnoid membrane after STA-middle cerebral artery (STA-MCA) and evaluated the clinical usefulness. MATERIALS AND METHODS: Between Mar. 2005 and Oct. 2010, extracranial-intracranial arterial bypass (EIAB) with/without encephalo-myo-synangiosis was performed in 88 cases (male : female = 53 : 35). As a control group, 51 patients (57 sides) underwent conventional bypass surgery without closure of the arachnoid membrane. Postoperative computed tomography (CT) scan was performed twice in three days and seven days later, respectively, for evaluation of the presence of subdural fluid collection and other mass lesions. RESULTS: The surgical result was excellent, with no newly developing ischemic event until recent follow-up. The additional time needed for arachnoid suture was five to ten minutes, when three to eight sutures were required. Post-operative subdural fluid collection was not seen on follow-up computed tomography scans in all patients. CONCLUSION: Arachnoid suturing is simple, safe, and effective for prevention of subdural fluid collection in EC-IC bypass surgery, especially the vulnerable ischemic hemisphere.

The Clinical Course of Subdural Hygroma with Head Injury / 대한신경손상학회지

OBJECTIVE: Traumatic subdural hygroma (T-SDG) has been generally treated using conservative management rather than surgical methods. This study was performed to evaluate the clinical course of T-SDG with radiologic studies. METHODS: A retrospective study was conducted among patients diagnosed with T-SDG from January 2011 to December 2011. The patients were categorized into two groups. Group A has the widest width of T-SDG below 8 mm, Group B more than 8 mm. Computed tomography (CT) and magnetic resonance imaging (MRI) were carried out in both groups. RESULTS: Seventy-four patients were confirmed with T-SDG and were grouped as follows: 44 patients in Group A and 30 patients in Group B. There was no significant difference in age and sex ratio between group A and B. It took more time to resolve T-SDG in Group B (95.2+/-86.4 days) than Group A (14.4+/-6.7)(p<0.001). However, no significant difference was observed in the Glasgow Coma Scale (GCS) between the groups. In 10 patients of Group B, T-SDG developed into chronic subdural hematoma and one of these patients underwent surgery. CONCLUSION: Most T-SDGs were resolved after some period in this study. Surgery does not seem to be necessary in resolving T-SDG.

The Clinical Course of Subdural Hygroma with Head Injury / 대한신경손상학회지

OBJECTIVE: Traumatic subdural hygroma (T-SDG) has been generally treated using conservative management rather than surgical methods. This study was performed to evaluate the clinical course of T-SDG with radiologic studies. METHODS: A retrospective study was conducted among patients diagnosed with T-SDG from January 2011 to December 2011. The patients were categorized into two groups. Group A has the widest width of T-SDG below 8 mm, Group B more than 8 mm. Computed tomography (CT) and magnetic resonance imaging (MRI) were carried out in both groups. RESULTS: Seventy-four patients were confirmed with T-SDG and were grouped as follows: 44 patients in Group A and 30 patients in Group B. There was no significant difference in age and sex ratio between group A and B. It took more time to resolve T-SDG in Group B (95.2+/-86.4 days) than Group A (14.4+/-6.7)(p<0.001). However, no significant difference was observed in the Glasgow Coma Scale (GCS) between the groups. In 10 patients of Group B, T-SDG developed into chronic subdural hematoma and one of these patients underwent surgery. CONCLUSION: Most T-SDGs were resolved after some period in this study. Surgery does not seem to be necessary in resolving T-SDG.

Risk Factors for the Post-Traumatic Hydrocephalus Following Decompressive Craniectomy in Severe Traumatic Injury Patients / 대한신경손상학회지

OBJECTIVE: The goal of this study was to assess the incidence and risk factors for post-traumatic hydrocephalus (PTH) following decompressive craniectomy (DC). An additional objective was to investigate the relationship between hydrocephalus and subdural hygroma (SDG) after DC. METHODS: We conducted a retrospective study of 94 patients who were admitted to our department between 2007 and 2010 with severe head injury requiring DC. Post-traumatic hydrocephalus was defined as: frontal horn index (FHI) > or =0.4 or modified FHI > or =0.33 accompanying transependymal edema; the presence of either clinical worsening or failure to make neurological improvement over time; and clinical improvement after ventriculoperitoneal shunt. Post-traumatic SDG was defined as the presence of low density at computerized tomography (CT) of more than 5mm thickness. RESULTS: Among the 94 patients, we could follow up more than 3 months and obtain more than 4 serial CT scans in 41 patients. PTH developed in 29.3% (12/41) and SDG developed in 48.8% (20/41) of these patients. The development of PTH was significantly associated with delayed craniplasty after DC and with interhemispheric SDG. No relationship was found between PTH and age, sex, Glasgow Coma Scale (GCS) score, intraventricular hemorrhage, subarachnoid hemorrhage, midline shift, basal cistern effacement, or cortical opening during DC. CONCLUSION: Hydrocephalus occurred in 29.3% of the patients with severe traumatic brain injury who required DC. Delayed cranioplasty and interhemispheric SDG after DC were risk factors for the development of PTH.

Risk Factors Associated with Subdural Hygroma after Decompressive Craniectomy in Patients with Traumatic Brain Injury : A Comparative Study

OBJECTIVE: Subdural hygroma (SDG) is a complication occurring after head trauma that may occur secondary to decompressive craniectomy (DC). However, the mechanism underlying SDG formation is not fully understood. Also, the relationship between the operative technique of DC or the decompressive effect and the occurrence and pathophysiology of SDG has not been clarified. Purpose of this study was to investigate the risk factors of SDG after DC in our series. METHODS: From January 2004 to December 2008, DC was performed in 85 patients who suffered from traumatic brain injury. We retrospectively reviewed the clinical and radiological features. For comparative analysis, we divided the patients into 2 groups : one group with SDG after craniectomy (19 patients; 28.4% of the total sample), the other group without SDG (48 patients; 71.6%). The risk factors for developing SDG were then analyzed. RESULTS: The mean Glasgow Outcome Scale (GOS) scores at discharge of the groups with and without SDG were 2.8 and 3.1, respectively (p<0.0001). Analysis of radiological factors showed that a midline shift in excess of 5 mm on CT scans was present in 19 patients (100%) in the group with SDG and in 32 patients (66.7%) in the group without SDG (p<0.05). An accompanying subarachnoid hemorrhage (SAH) was seen in 17 patients (89.5%) in the group with SDG and in 29 patients (60.4%) in the group without SDG (p<0.05). Delayed hydrocephalus accompanied these findings in 10 patients (52.6%) in the group with SDG, versus 5 patients (10.4%) in the group without SDG (p<0.05). On CT, compression of basal cisterns was observed in 14 members (73.7%) in the group with SDG and in 18 members of the group without SDG (37.5%) (p<0.007). Furthermore, tearing of the arachnoid membrane, as observed on CT, was more common in all patients in the group with SDG (100%) than in the group without SDG (31 patients; 64.6%) (p<0.05). CONCLUSION: GOS showed statistically significant difference in the clinical risk factors for SDG between the group with SDG and the group without SDG. Analysis of radiological factors indicated that a midline shifting exceeding 5 mm, SAH, delayed hydrocephalus, compression of basal cisterns, and tearing of the arachnoid membrane were significantly more common in patients with SDG.

Management of Subdural Fluid Collection Following Surgery for Ruptured Aneurysm / 대한뇌혈관외과학회지

OBJECTIVE: This study aimed to evaluate the clinical course of subdural fluid (SDF) collection following surgery for a ruptured aneurysm and to set up a management plan for it. METHODS: Of 288 patients who underwent open aneurysm surgery for a ruptured aneurysm, 97 patients (33.7%) had impaired cerebrospinal fluid circulation in the form of subdural fluid collection or hydrocephalus during the postoperative period. We categorized these patients into 3 groups. Group A comprised patients who experienced spontaneously resolved postoperative SDF collection. Group B comprised patients who experienced a postoperative SDF collection that evolved into internal hydrocephalus. Group C comprised patients who experienced hydrocephalus without subdural fluid collection during the postoperative period. We retrospectively reviewed radiographic images and clinical data to determine the differences between the three groups with respect to age, initial clinical grade, and Fisher grade. RESULTS: Group B and group C had similar proportions of patients over 60 years of age in comparison to group A. Compared to group A, group B had a greater proportion of patients whose initial Hunt and Hess grades (HHG) were III, IV, or V (p = 0.040), and group B had a larger proportion of patients whose initial Fisher grades (FG) were III or IV (p = 0.020). CONCLUSION: Based on our understanding of SDF collection's clinical course and mechanism, we carefully suggest that clinicians consider the presence of cortical atrophy, the initial CT grade, and the clinical grades when establishing a treatment plan for SDF collection.

Escherichia Coli Subdural Empyema Following Subdural Hygroma in Elderly Patient

Subdural empyema of the brain is an uncommon disorder that occurs more frequently in children than in adult. Authors report a very rare of subdural empyema following the subdural hygroma after mild head injury. The exact mechanism of infection is not known. However, we have to consider subdural infection as one of differential diagnosis in elderly patient with subdural hygroma when new abnormal density lesion is developed in the subdural space.

Massive Intracerebral Hemorrhage Following Drainage of Subdural Hygroma

Subdural hygromas are easily treated by trephination and drainage. Therefore, most neurosurgeons do not consider subdural hygromas seriously. However, various complications including intracerebral hemorrhage may develop after rapid drainage of subdural hygroma although rare. Postoperative intracerebral hemorrhage presents with a rapid deterioration of consciousness and focal neurological deficits occurring immediately after drainage of the subdural hygroma. The authors present an unfortunate massive intracerebral hemorrhage and pneumocephalus following drainage of the bifrontal subdural hygroma. The patient subsequently died. To prevent this disastrous complication, close neurosurgical observation and gradual drainage under a closed system seem mandatory. Possible pathogenic mechanisms for this unfavorable complication is discussed with a review of pertinent literatures.

Effectiveness of Early Surgery in Children with Traumatic Subdural Hygroma

OBJECTIVE: This study was performed to evaluate the usefulness of early operation in children with traumatic subdural hygroma. METHODS: The subjects were nine patients (Glasgow coma scale (GCS) score was below 10 and age was below 10 years old) who developed subdural hygroma after trauma between January 2000 to December 2002. Subduroperitoneal shunt was performed in one group and not performed in the other group. We analyzed the GCS score on admission and at 1 year after operation. Overall clinical results were evaluated retrospectively. RESULTS: Patients who underwent operation exhibited higher GCS scores at 1 year after trauma compared to those in the patients who were treated by conservative therapy(p<0.05). CONCLUSION: The early operation could be an effective treatment to children with subdural hygroma who showed delayed improvement of consciousness and to patients with hygroma that didn't decrease or was above moderate amount.

The Surgical Results of Traumatic Subdural Hygroma Treated with Subduroperitoneal Shunt

OBJECTIVE: The detection rate of traumatic subdural hygroma(TSH) has increased after the development of computed tomography and magnetic resonance imaging. The treatment method and the mechanism of development of the TSH have been investigated, but they are still uncertain. This study is performed to evaluate the effectiveness of subduroperitoneal shunt in traumatic subdural hygroma. METHODS: Five hundred thirty six patients were diagnosed as TSH from 1996 to 2002, among them, 55 patients were operated with subduroperitoneal shunt. We analyzed shunt effect on the basis of clinical indetails, including the patient's symptoms at the diagnosis, duration from diagnosis to operation, changes of GCS, hygroma types. We classified the TSH into five types (frontal, frontocoronal, coronal, parietal and cerebellar type) according to the location of the thickest portion of TSH. RESULTS: The patients who have symptoms or signs related to frontal lobe compression (irritability, confusion) or increased intracranial pressure (headache, mental change), had symptomatic recovery rate above 80%. However, the patients who have focal neurological sign (hemiparesis, seizure and rigidity), showed recovery rate below 30%. The improvement rate was very low in the case of the slowly progressing TSH for over 6weeks. We experienced complications such as enlarged ventricle, chronic subdural hematoma, subdural empyema and acute SDH. CONCLUSION: Subduroperitoneal shunt appears to be effective in traumatic subdural hygroma when the patients who have symptoms or signs related to frontal lobe compression or increased ICP and progressing within 5weeks.

Surgical Treatment of Subdural Hygromas in Infants and Children

OBJECTIVE: There is no acceptable indication and treatment of choice for infantile and child subdural hygroma and there are only a few reports about that in Korea. So the authors studied the clinical findings of infantile and child patients with subdural hygroma to improve the understanding and to suggest a standard treatment method. METHODS: The authors retrospectively evaluated the causes, preoperative symptoms, radiological thicknesses, and postoperative results of 25patients with subdural hygroma who received surgical therapy. RESULTS: There were 16boys and 9girls whose median age was 6months(range 2~120months). The main clinical manifestations were seizures, increased intracranial pressure, macrocrania and alteration of consciousness. Radiological thicknesses of the subdural hygroma varied from 7mm to 42mm and postoperative changes of thickness(y) could be expressed with the factor of month(x): y = -1.32 x +11.8 in subdural drainage, and y = -1.52 x +14.9 in subduroperitoneal shunts. Of the 25patients, 2 (50%) were successfully treated by aspiration, 13 (59%) by subdural drainage, and 9 (69%) by subduroperitoneal shunt. CONCLUSION: It is suggested that the diagnosis and treatment of subdural hygroma in infants and children should be carefully addressed because of its high prevalence in children, and especially in infants. It is also suggested that the subdural drainage could be primary initial treatment method because it is simpler than a shunt, and since our data show that there is no statistical difference in postoperative recovery duration between the two operative methods.

Preoperative Cisternoscintigraphy As a Guide to Therapeutic Decision Making for Cystic Subdural Hygroma / 대한핵의학회잡지

We report a case of a patient with cystic subdural hygroma who underwent pre-operative Tc-99m DTPA cistrenoscintigraphy to determine the course of operation. A 68-year-old female was admitted to the department of neurosurgery because of acute subarachnoid hemorrhage. After emergency ventricular drainage, the hydrocephalus and cystic subdural hygroma in the right fronto-temporal area developed. She underwent Tc-99m DTPA cisternoscintigraphy to evaluate the type of hydrocephalus, which revealed obstructive communicating hydrocephalus and the communication between the subdural hygroma and the subarachnoid space. As a result of these findings, she underwent the ventriculo-peritoneal shunt operation without removal of the subdural hygroma. Post-operative brain CT showed nearly normalized shape and size of the right ventricle and disappearance of subdural hygroma. We recommend the pre-operative cisternoscintigraphy in patients with complex hygroma to evaluate the communication between subdural hygroma and the subarachnoid space.

A Prospective Study on the Incidence, Patterns and Premorbid Conditions of Traumatic Subdural Hygroma

The origin and clinical importance of subdural hygroma(SDG) are still uncertain. Its pathogenetic mechanism and natural history have not yet been settled. Although the incidence of traumatic SDG has been reported to be 5-20% of posttraumatic space-occupying lesions, the true incidence has not been documented in prospective study. Therefore, authors have tried to determine the incidence of traumatic SDG prospectively during past six months. Serial computed tomography(CT) or magnetic resonance imaging(MRI) studies were done in all patients who were admitted to our department after head injuries. Data on the age, sex, Glasgow coma scale(GCS) on admission, and initial CT findings were collected and analyzed to determine the true incidence, pattern and premorbid conditions for the development of traumatic SDG. Serial CT or MRI scans were performed on the date of admission, the second to sixth hospital day, and the seventh to fourteenth hospital day. Study population consisted of 115 patients, excluding 31 expired, discharged, or transferred patients within a week. Subdural hygroma was noted in 42(35.6%) patients. It shared 45.2% of posttraumatic mass lesion. More than half (54.7%) of patients aged 40 or more had subdural hygromas. They were generally delayed lesions, due to the fact that most of them(81%) were observed at four days or more after the injury. All hygromas were located at the frontal or fronto-temporo-parietal regions. Bilaterality was seen in 54.7%. SDGs occurred earlier when the age of the patients were 40 years old or more(p=0.037). It occurred earlier when the initial CT scans were normal, when there was no accompanying traumatic intracranial lesions, and high GCS on admission. However, these differences were statistically not significant(p>0.05). These results suggest that the premorbid conditions for the development of subdural hygroma were sufficient potential subdural space and separation of the dural border cell layer, although former seemed to be more important that the later. Osmotic dehydration in the aged victims should be serially reevaluated, because the subdural hygroma may develop when the intracranial pressure is excessively low.

Radioisotope Cisternographic Analysis of Post-operative Subdural Hygroma after Aneurysmal Surgery

Authors analyzed the post-operative subdural hygroma using radioisotope(RI) cisternography in 30 cases following aneurysmal surgery with pterional approach from October, 1995 to March, 1996. Age, CSF flow from basal cisterns, and etent of opening of Liliequist's membrane during operation were significantly related to the development of post-operative subdural hygroma. Computed tomography(CT) scan of brain and RI cisternography were performed in all patients at three weeks following operations. RI diffusion time from the interpeduncular cistern to the cerebral convexity of ipsilateral side with surgically opened Liliequist's membrane was compared with contralateral nonoperated normal side. Diffusion time of ipsilateral side(mean 5.2+/-8.4hr) was faster than that of contralateral one. Age, cerebrospinal fluid(CSF) from basal cistern, and extent of opening of Liliequist's membrane during operation were significantly related to development of post-operative subdural hygroma. Development of subdural hygroma after pterional approach for aneurysmal operations in our series is believed to be caused by stagnation of CSF in the convexity until its absorption into the arachnoid villi. Increased CSF flow from the infratentorial space to the supratentorial space through extensively opened Liliequist's membrane is considered to contribute development of its formation.

Relations among traumatic subdural lesions

Acute subdural hematoma (ASDH), chronic subdural hematoma (CSDH) and subdural hygroma (SDG) occur in the subdural space, usually after trauma. We tried to find a certain relationship among these three traumatic subdural lesions in 436 consecutive patients. We included all subdural lesions regardless of whether they were main or not. We evaluated the distribution, age incidence and interval from injury to diagnosis of these lesions, and the frequency of new subdural lesions in each lesion. ASDH constituted 68.6%, SDG 15.8%, and CSDH 15.6%, Age incidence of CSDH was similar to that of SDG, but differed from that of ASDH. Mean interval from injury to diagnosis was 0.4 days in ASDH, 13.4 days in SDG, and 51.6 days in CSDH. Focal brain injuries accompanied in 37.5% of ASDH, 5.8% of SDG, and no CSDH. In ASDH, 2 recurrent ASDHs, 17 SDGs and 9 CSDHs occurred. In SDG, 3 postoperative ASDHs and 8 CSDHs occurred. In CSDH, 2 postoperative ASDHs, 2 SDGs and 1 CSDH occurred. These results suggest that the origin of CSDH is not only ASDH, but also SDG in upto a half of cases. SDG is produced as an epiphenomenon by separation of the dural border cell layer when the potential subdural space is sufficient. A half of CSDHs may originate from ASDHs. ASDH may occur in CSDH by either a repeated trauma or surgery. Such transformation or development of new lesions is a function of a premorbid condition and the dynamics between the absorption capacity and expansile force of the lesion.

Subdural Hygroma Following Pterional Approach for Cerebral Aneurysmal Surgery

The occurrence of subdural hygroma following pterional approach for intracranial aneurysm at Yeungnam University from March 1994 to December 1994 was studied with regard to the patients age, location of aneurysm, preoperative ventricular dilatation, operation time, cortex color, CSF flow, opening degree of Liliequist membrane, dissection degree of sylvian fissure, postoperative intradural air amount and day for mannitol infusion using chi-square test. The following results and conclusions were obtained: 1) Subdural hygroma was observed in 28 of 53 patients(52.8%). 2) The patient's age was significantly related to the occurance of subdural hygroma(p<0.05). 3) CSF flow through the basal cistern was significantly related to the occurrence of subdural hygroma(p<0.05). 4) In cases of good CSF flow, degree of Lilieqist membrane opening was significantly related to the occurrence of subdural hygroma(p<0.05). Preserving of Liliequist membrane will minimize the occurrence of subdural hygroma.