Prior to the fireline debate concerning randomized controlled clinical trials(RCT)and medical ethics, the author has reviewed the relationship of these issues with evidence-based medicine(EBM), dealing also with some misunderstanding of EBM in Japan, and the relationship between EBM and ethics-based medicine, not from the viewpoint of a neurosurgeon, but from that of a neurologist.

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The acronym EBM suggests that patients be treated as if they did not have their own unique character. This is because the evidence collected from randomized double-blind studies is the gold standard in EBM. In medicine, utilitarian principle dictates that as many lives should be saved as possible and to that end each patient is counted as a single interchangeable unit. However, this raises the objection that doctors are more interested in treating the disease than the patient. Both doctors and patients are unhappy with these circumstances. It takes many years of experience to acquire neurosurgical techniques. The same results cannot be obtained merely from following the processes of the established techniques. In addition, a single operation cannot be divided by a team of surgeons as though they were a team of architects contributing to the design of a building where the technical equality of the team is not essential. Therefore for the 21 century, an "individual or narrative-based Medicine" is proposed. As symbolized by a popular phrase in Japan "We introduce knowledge and techniques from abroad but have our own soul", culture has long been imported, translated and assimilated from China and the West. In the modern age, however, with the rapidity of scientific advances and the growing utilitarian orientation, "knowledge and techniques are being directly imported together with a foreign soul". Trends of globalization are understandable, but it is deeply dangerous to lose individual cultural identities. In order to preserve pluralism and the historical continuity of culture it is important to practice naturalized medicine appropriate for each culture.

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In Japan, treatments have generally been provided according to "experience-based medicine". On the other hand, treatment strategies in the US and European countries have typically been established based on the evidence obtained in large-scale clinical trials. Recently, this concept of "evidence-based medicine" has been introduced in Japan, where it is considered a great progress. However, large-scale clinical trials conducted in the US and European countries have several deficits : their follow-up period is usually too short, and only less than 10% of the patients enrolled and judged eligible for the study are actually randomized to the study. The large-scale clinical studies comparing the usefulness of PTCA and CABG for revascularization in cases of multi-vessel ischemic heart disease have concluded that PTCA could replace CABG without any significant differences in the incidence of myocardial infarction and survival prognosis during the follow-up period. However, there is an interesting investigation of prognosis of patients who were enrolled but not randomized to the study because of their physician's refusal, which reported that the prognosis for both PTCA and CABG was better in enrolled patients than in randomized patients. This may be explained by the possibility that experienced physicians intentionally selected PTCA for their patients with double vessel disease and CABG for those with severe triple vessel disease, which indicates that experience based medicine is likely to lead to better consequences than treatment in randomized trials. It should be noted that large-scale randomized trials have their limitations, and it is important not to take and apply the study results directly, but rather to make a prudent decision in each individual case.

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UCAS JAPAN(Unruptured Cerebral Aneurysm Study of Japan)is a large scale prospective cohort study to investigate the natural history and treatment results of unruptured intracranial aneurysms. The method adopted in the protocol is suitable under the present situation of knowledge and data for unruptured intracranial aneurysms. UCAS JAPAN provides the risk of rupture and treatment result for every peculiarity of unruptured aneurysms encountered in clinical practice and maintains a large data bank that may answer various hitherto unanswered questions. This study is only possible in Japan, where numberous numbers of asymptomatic unruptured intracranial aneurysms are being found in the brain dock. Consequently, a significant contribution to the international community is expected.

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It has not been proven whether EC-IC bypass surgery is effective for stroke prevention, or the amelioration of neuropsychological function. To answer these questions, the Japanese EC-IC bypass trial(JET)was started in 1998. This study is well designed to evaluate the efficacy of EC-IC bypass surgery as a multicenter randomized controlled trial(RCT)at the level I study of evidence-based medicine. Generally, it is difficult to design the RCT to prove the efficacy of surgical treatment, because there is a lot of "bias" hidden in each step of RCT. In this paper, we indicate several solutions for suppressing each bias in JET, and important points to organize this type of clinical study, which refine the study design more scientifically. The study is running smoothly, and we will reach the final goal by 2003. Although the medical level in Japan is high, such as diagnostic technique, therapeutic equipment, and so on, its medical treatment is not highly appreciated abroad. Accordingly, we did not pay any attention to the nation-wide study of diagnostic/therapeutic matters, irrespective of efforts by individual institute for the many excellent pilot studies. We stress the importance of organizing multicenter clinical trials at a higher evidence level.

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Sixteen patients with single metastatic brain tumor underwent SPECT using N-isopropyl-p-(^<123>I)iodoamphetamine(^<123>I-IMP)before and after radiosurgery. Influence of treatment was evaluated using three-dimensional SPECT images, threshold-voxel graphs and changes in the volume of the peritumoral hypoperfusion area. A three-detector type scanner, the PRISM3000, was also used. SPECT scanning was performed for 30 minutes after intravenous administration of ^<123>I-IMP with sequential scans every 1 minutes. The data obtained 16-30 minutes after administration were processed using a low-pass ramp filter, and three-dimensional SPECT images were constructed from these data using the Application Visualization System(AVS). Furthermore, a threshold-voxel graph was plotted and the volume of the peritumoral hypoperfusion are was calculated. SPECT was performed before radiosurgery, and 1 day, 1 week, and 1 month after, and these data were compared. Three-dimensional SPECt presented the area of peritumoral hypoperfusion as a deficit image and changes were evaluated visually. Threshold-voxel graphs were evaluated as follows : changes in voxels with a threshold of 40-50% indicated a hypoperfusion area, and changes in voxels with a threshold of 70-95% indicated a hyperperfusion area in the tumor side hemisphere. The volume of the peritumoral hypoperfusion area was calculated using the voxel difference between the tumor side and normal hemispheres. Our results showed that the peritumoral hypoperfusion area gradually decreased after an initial first-day increase following radiosurgery. Visual three-dimensional SPECT allowed us to monitor both the volume of the peritumoral hypoperfusion area of metastatic brain tumors after radiosurgery by means of a threshold-voxel graph and changes in the peritumoral hypoperfusion area.

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Purpose : Three dimensional digital subtraction angiography(3D-DSA)is a new tool which combines the benefits of both conventional cerebral angiography and three dimensional computed tomographic angiography(3D-CTA). In the present study, cerebrovascular lesions were evaluated with 3D-DSA. Method : Five occlusive cerebrovascular lesions, 31 cerebral aneurysms, and 2 arteriovenous malformations(AVMs)were evaluated with 3D-DSA. Angiography was performed using the Seldinger method in all cases. To produce three dimensional vascular images for the 3D-DSA system, a single plane C-arm was rotated by 200゜ with infusing 15 to 20 ml of the contrast material. The data captured from 44 mask images and 44 contrast images were then transferred to a computer workstation and reconstructed three-dimensionally. Results : 3D-DSA demonstrated the following benefits as compared with conventional cerebral angiography : (1)The size of the aneurysm and its neck could be accurately measured, with a difference of less than 0.5mm between measurements taken from the computer screen of the 3D-DSA system and the operation field. (2)The lesion and the surrounding vascular structure could be recognized three dimensionally, which was of great benefit for simulating the operation. In cerebral aneurysms, the shape of the aneurysm, location of the bleb, and relationship between the aneurysm and the parent arteries were demonstrated clearly. In AVMs, the architectures of the feeders, drainers, and nidus were also demonstrated clearly, even when located peripherally. (3)An endovascular image was made available. 3D-DSA also demonstrated the following benefits as compared with 3D-CTA : (1)Visualization of the arteries, including those peripheral, was very clear, which provided satisfactory information regarding the aneurysmal neck and parent arteries for performing the operation. (2)Images of the cerebral arteries were not disturbed by the cerebral veins or skull base bones. As a result, lesions in the internal carotid artery, such as IC-PC aneurysms, were clearly demonstrated without any disturbance of the skull base bone or cavernous sinus. (3)Fine arterial branches and perforating arteries could be visualized. One disadvantage of the 3D-DSA was that bony structure information could not be provided. In cases of paraclinoid and basilar bifurcation aneurysms, 3D-DSA should be combined with 3D-CTA to clarify the relationship between these lesions and the skull base bone. Conclusions : Although 3D-DSA requires the Seldinger method to obtain clear images, it offers various benefits which are very useful for evaluating such cerebrovascular lesions as cerebral aneurysms and AVMs, as well as for simulating the operation.

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The choice of treatment for subdural empyema especially with interhemispheric lesion is controversial. Unilateral or bilateral convexity empyemas are directry related to the diagnosis by CT. The case presented here was a 74-year-old woman who had multiple, i.e., bilateral convexity, interhemispheric and right frontal basis, subdural empyemas. The condition started with sudden headache and high fever. At first, she was diagnosed as bilateral convexity subdural empyemas by contrast-enhanced CT. The lesions were treated successfully with burr hole surgery and antibiotics. She was discharged without any apparent deficits. As in our case, when a causative organism is detected by burr hole surgery from the subdural space which is not associated with interhemispheric lesion, conservative therapy with antibiotics is considered important because it is less invasive.

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A 47-year-old male presented with a ruptured "true" posterior communicating artery aneurysm(Pcom AN)manifesting as semicoma and left hemiparesis. An open direct surgery could not be performed because his neurological state was critical in the acute stage. He died of rebleeding of the aneurysm before the intentional delayed operation was performed. In general, a "true" posterior communicating artery aneurysm is rare. Diagnosis and treatments of patients with this aneurysm, particularly those in a poor neurological state are discussed.

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A 62-year-old-man was admitted to the hospital with complaints of headache, nausea and gait disturbance. Neurological examinations disclosed truncal ataxia and broad based gait. Magnetic resonance images demonstrated a cystic tumor, 4cm in diameter, in the cerebellar vermis, the margin of which was enhanced by Gadolinium-DTPA. At operation, the tumor was reddish, highly vascular, and had no continuity with the fourth ventricle, and it seemed to be a hemangioblastoma. It consisted of clear cells, showing perivascular pseudorosettes on light microscopy and the tumor cells were immunoreactive for glial fibrillary acidic protein(GFAP). Therefore, we diagnosed this case as a clear cell ependymoma in the vermis. Clear cell ependymoma is a rare variant of ependymoma and that in the posterior fossa is reviewed and discussed.

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