The clinical, radiological, and operative factors of recurrent chronic subdural hematoma (CSDH) were retrospectively analyzed in 116 patients with CSDH in 134 hemispheres, treated by one burr hole surgery. The correlation of recurrence was evaluated with personal and clinical factors such as age, sex, history of head injury, and interval from onset of initial symptoms to hospitalization; laboratory findings such as bleeding tendency and liver function; computed tomography (CT) findings such as hematoma density and brain atrophy; and operative findings such as additional procedures and postoperative residual air. The recurrence group (RG) included 10 hemispheres (7.5%) in 10 patients (8.6%). The interval from onset of symptoms to hospitalization was significantly shorter in the RG than in the nonrecurrence group (NRG). Headache was more frequently seen in the RG than in the NRG. Density of hematoma on CT was classified into five types: Low, iso, and high density, niveau, and mixed, and the incidence of recurrence was 0%, 2.3%, 17.2%, 12.5%, and 6.5%, respectively. Larger amounts of residual air in the postoperative hematoma cavity were associated with recurrence of CSDH. CSDH that progresses rapidly in the acute stage and appears as high density on preoperative CT is associated with a high incidence of recurrence. Intraoperative air invasion to the hematoma cavity should be avoided to prevent recurrence.

This study was undertaken to evaluate the histological reaction of cultured endothelial cells to endovascular embolic materials in vitro. Endothelial cells were isolated and cultured from a canine carotid artery. Embolic materials (platinum microcoils, polyvinyl alcohol particles, silicon balloons, or silk threads), either in their normal state or after having been coated with type 1 collagen, fibronectin, or laminin, were placed on endothelial cells and cocultured for 6, 12, and 24 hours and 2, 3, 7, 14, and 21 days. The cocultures were investigated histologically using a scanning electron microscope. Endothelial cells were not found on any uncoated embolic materials, even at 21 days. On the materials coated with fibronectin or laminin, endothelial cells began to proliferate in 7 days, covering the materials extensively in 14 days. On the other hand, endothelial cells began to proliferate on the collagen-coated materials in 3 days, covering them extensively in 7 days and reaching confluence with a cobblestone pattern in 21 days. The densities of endothelial cells on collagen-coated materials were much higher than those observed on the materials coated with other extracellular matrices. Future advantages of the clinical use of collagen-coated embolic materials in interventional treatment are discussed.

MRA could be useful for management of cerebral vasospasm, although it cannot become a practical alternative to conventional angiography.

The purpose of this study was to evaluate the role of the endothelial cell reaction after endovascular coil embolization for the treatment of intracranial aneurysms. A scanning electron microscopic (SEM) study of the platinum coil, embolized into a middle cerebral aneurysm in a 35-year-old woman and subsequently removed surgically eight months later, revealed no endothelial coverage on the coil. This finding prompted us to perform experimental studies. In the first in vitro study, endothelial cells from gerbil brain microvessels and canine carotid arteries were co-cultured with either bare-form platinum coils or type-1 collagen-coated coils for up to three weeks, and the endothelial cell population on the coils was ascertained. In the second in vivo study, platinum coils coated with type-1 collagen were delivered endovascularly into canine carotid arteries, while the contralateral side was treated with bare-form coils, and endothelialization over the coil was investigated. SEM studies revealed that no endothelial cells, either from gerbil brain microvessels or from canine carotid artery, were found on the uncoated coils, whereas gerbil endothelial cells began to proliferate on the collagen-coated coils in three days, covering extensively in one week and reaching confluence in two weeks in vitro. The in vivo canine study demonstrated that bare-form platinum coils did not show endothelial coverage until two weeks, but endothelial cells proliferated directly on the collagen-coated coils in three days, and coils were completely covered in two weeks. These results supported the SEM study of our case and several human histopathological reports in the literature in that endothelial cell coverage in the orifice of the intracranial aneurysm is exceptional after endovascular treatment. But if some extracellular matrix, like collagen in our study, is prepared, coverage could be possible, as is seen in a few human cases. Biological modification of the platinum coils, such as collagen coating, is awaited for the better long-term results of endovascular coil embolization without recanalization of the treated intracranial aneurysms.

The technique of nidus embolization with N-butyl-2-cyanoacrylate (NBCA) glue is presented. The microcatheter is navigated into the nidus and the tip is set in a wedged position. A diluted mixture of NBCA in ethiodized oil (a 25% mixture is mainly used) is injected very slowly, using complete column technique. Using this technique, the progression of glues in the nidus can be seen easily, which leads to improve accuracy and effectiveness of embolization. The mean blood pressure is maintained 15% to 20% below baseline for several days after the embolization to prevent hemorrhage caused by normal pressure breakthrough. We believe this technique is very useful and effective method for the treatment of arteriovenous malformations. However, considerable experience in this technique should be required.

The purpose of this study is to evaluate the long-term stability of embolized aneurysms using the volume embolization rate (VER). One hundred and six aneurysms in 96 patients who were treated with Guglielmi detachable coils were selected for this study. Follow-up angiography was performed at six or more months after initial treatment. Every aneurysm was packed as densely as possible, however, the percentage of stability varied according to the size of the aneurysm or the size of the aneurysm neck. The percentage of stable aneurysm was 82% (56/68) in small aneurysms with small necks, 68% (13/19) in small aneurysms with wide necks and 42% (8/19) in large aneurysms. The mean VER of embolized aneurysms in each size was 30%, 22% and 17%, respectively. There was a correlation between the percentage of stable aneurysms and the mean VER. On the other hand, there seemed to be a difference of VER for the stability of embolized aneurysms between ruptured aneurysms and unruptured ones. In small aneurysms with small necks, the stability of embolized aneurysms in ruptured ones was obtained only when the VER was greater than 30%, whereas it was found in unruptured ones even though the VER was less than 20%. In conclusion, the long-term stability of embolized aneurysms was obtained in small-sized aneurysms, especially small neck aneurysms, and unruptured ones. The VER is a good, objective index to predict the long-term stability of embolized aneurysms.

The purpose of this study is to evaluate the efficacy and problems of the embolization for cerebral arteriovenous malformations (AVMs) with diluted cyanoacrylate adhesives. Twelve consecutive AVM cases were treated with N-butyl-2-cyanoacrylate (NBCA) glues between January 1997 and July 1998. The mean age of the patients was 37 years old. Intracerebral hemorrhage was the presenting symptom in seven cases, seizure in three, headache in one and mental deterioration in one. According to the classification of Spetzler and Martin, seven were Grade 11, five were Grade III. We used a mixture of NBCA (normally 25% Histoacryl, 75% Ethidol) for embolization. Microcatheter was navigated into the nidus and the tip of the catheter was set in a wedged position. Then the glue was injected using complete column technique. Nineteen sessions of embolization were performed in 12 patients. The mean volume of each nidus was reduced from 22.5 ml to 3.4 ml (85%) after embolization. Four cases were cured by embolization alone. Surgical resection was performed after embolization without any residual nidus in three cases. Five were treated with stereotactic radiosurgery following embolization. One was completely cured in 18 months after and the other four have been decreasing their sizes of nidus. One case was suffered from delayed intracerebral hemorrhage three days after embolization, and resulted in mild hemiparesis and memory disturbance. The others had no complications and were clinically improved or unchanged after embolization. It is possible to embolize the nidus of AVMs more accurately and safely with diluted mixture of NBCA, compared with the method using relatively higher concentration of NBCA glues. This technique is useful and effective method for the treatment of AVMs.

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