Shinichi Tamatani

Detection of delayed cerebral vasospasm, after rupture of intracranial aneurysms, by magnetic resonance angiography.

OBJECTIVE The goal of this study was to assess the value of magnetic resonance angiography (MRA), compared with conventional angiography, in the diagnosis and follow-up monitoring of delayed cerebral vasospasm after subarachnoid hemorrhage resulting from rupture of intracranial aneurysms. METHODS For 32 patients undergoing examination by both MRA and conventional angiography during the period of risk for vasospasm, on the same day, the frequency and severity of and sequential changes in vasospasm were evaluated. The three-dimensional time-of-flight method was used. MRA was performed three times, i.e., before, during, and after the period of risk for vasospasm. Conventional angiography was performed twice, i.e., at admission and during the period of risk for vasospasm. Vasospasm was assessed at 22 regions of the cerebral arteries, including the bilateral anterior cerebral (A1, A2, and A3 segments), middle cerebral (M1, M2, and M3 segments), internal carotid (C1 and C2 segments), posterior cerebral (P1 and P2 segments), and posterior communicating arteries. RESULTS Seven patients were excluded because of poor MRA images. Twenty-two of 25 patients (125 arteries) showed vasospasm in conventional angiograms. Nineteen of the 22 patients also showed vasospasm in MRA images; however, 57 arteries (45.6%) were diagnosed as showing vasospasm by MRA, and 59 (47.2%) could not be evaluated because of artifacts. For the remaining three patients (nine arteries, 7.2%), vasospasm could not be detected by MRA. Sequential changes in vasospasm could be well evaluated by MRA. CONCLUSION MRA could be useful for management of cerebral vasospasm, although it cannot become a practical alternative to conventional angiography.

Histological evaluation of endothelial reactions after endovascular coil embolization for intracranial aneurysm. Clinical and experimental studies and review of the literature.

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.

Efficacy of diluted NBCA mixture for embolization of arteriovenous malformations.

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.

Embolization of Arteriovenous Malformation with Diluted Mixture of NBCA

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.

Evaluation of the stability of intracranial aneurysms occluded with guglielmi detachable coils.

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.

Evaluation of Local Intra-Arterial Fibrinolytic Therapy for Acute Middle Cerebral Artery Occlusion

Fibrinolytic therapy for acute ischaemic stroke has been investigated in several clinical trials, with various protocols. This retrospective study was undertaken to evaluate the efficacy and limitation of local intra-arterial fibrinolytic therapy using urokinase (UK) in patients with acute middle cerebral artery occlusion. Fifty patients were treated with local intra-arterial fibrinolytic therapy within six hours after onset of symptoms. The median National Institutes of Health Stroke Scale (NIHSS) score was 17 (range, 6 to 28). Two hundred and forty thousand IU of UK was administered through a mi-crocatheter for 20 minutes. When arterial recanalization was not achieved, a second or third infusion was performed. Maximum dosage of UK was 0.96 × 106 IU. Recanalization efficacy was evaluated at the end of fibrinolytic therapy and intracranial haemorrhage was assessed within 24 hours. Clinical outcome was evaluated three months after ictus with modified Rankin scale (RS). Thirty-nine patients (78%) obtained recanalization. Twenty-nine of 39 (74%) showed clinical improvement just after treatment. On the other hand, only 18% patients (2/11) who did not recanalize demonstrated improvement. Twenty-five of 50 (50%) patients recovered to RS score 0 or 1, however, only 28% of patients (5/18) with proximal M1 occlusion obtained good outcome and 39% of them (7/18) died. The mean time interval from onset to treatment did not affect outcome. The overall incidence of haemorrhagic event (HE) within 24 hours was 36%, however, 78% of patients with proximal M1 occlusion showed HE. Only one patient with HE clinically deteriorated. In conclusion, local intra-arterial fibrinolytic therapy could be a safe and effective method for acute middle cerebral artery occlusion, however, indication of this therapy for patients with proximal M1 occlusion should be carefully decided.