[De novo aneurysm after ten days from the onset of SAH].

A 56-year-old man presented with severe headache. Neurological examinations found no abnormalities and no disturbance of consciousness. CT revealed a subarachnoid hemorrhage. DSA showed an aneurysm located at the junction of the right internal carotid artery and the anterior choroidal artery. Next day, neck clipping was performed. The aneurysm adhered to the temporal lobe, and it seemed without doubt that it was a ruptured aneurysm. On day 10, we performed a carotid angiography on schedule. DSA revealed a newly arisen aneurysm originating from the middle cerebral artery close to the origin of the lenticulostriate artery and a vasospasm in the internal carotid artery and the middle cerebral artery. On day 14, we again performed surgery. The aneurysm was embedded in the insular cortex, but it seemed to be a non-ruptured aneurysm. After surgery, the patient had no apparent neurological deficits, and he returned to normal daily life. De novo aneurysms have been discovered after at least a few years. This case is very rare because the aneurysmal formation is of much a short interval.

[High b-value diffusion-weighted imaging of acute brain infarction].

High b-value diffusion-weighted (DW) imaging obtained with a b-value of 2,000 s/mm2 offers theoretical advantages over DW imaging obtained with a b-value of 1,000 s/mm2 for detection of acute brain infarction. The purpose of this study was to determine whether high b-value DW images (b=2,000) are better than b=1,000 images for detection of diffusion change in patients with acute brain infarction. We compared diffusion-weighted (DW) images obtained with a b-value of 1,000 s/mm2 with those obtained with a b-value of 2,000 s/mm2 in 84 patients with small lesions (brain stem infarction, lacuna infarction) examined within 24 hours of clinical onset. Qualitative analysis was performed concerning lesion conspicuity. In quantitative analysis, contrast ratios (CR) were measured and findings of b=1,000 and b=2,000 images were compared. False-negative rate of b=1,000 and b=2,000 images were 23.8% and 3.6%, respectively, relative to the presense or absense of infarction on the follow-up MR or CT images. On qualitative analysis, lesions were more conspicuous on b=2,000 images. On quantitative analysis, as the b-value increased, mean CR increased. DW images aquired with a b-value of 2,000 s/mm2 were better than DW images aquired with a b-value of 1,000 s/mm2 for detection of diffusion change in patients with acute brain infarction.

[Aneurysms at the early branch of middle cerebral artery].

The cortical arteries arising from the proximal (Ml) segment of the middle cerebral artery (MCA) are called "early branches". We retrospectively analyzed clinical features in 10 patients with aneurysms located at the early branches of MCA. The incidence of these aneurysms was 9.5% among 95 MCA aneurysms. Patients consisted of 4 males and 6 females. Ages were 33-77 years old (average of 54.4). Four patients presented with subarachnoid hemorrhage (2 of them had intracerebral hematoma). The aneurysms were classified into 2 groups, the group of the early frontal branch (EFB: 7 cases) and the early temporal branch (ETB: 3 cases). All aneurysms were smaller than 6mm in diameter. The surgical treatment was performed through the pterional approach. Poor outcome occurred in 3 ruptured aneurysms of EFB (MD 1, SD 1, and D 1). At surgery, it is necessary to produce the working space by dissecting sylvian fissure sufficiently and to prevent ischemic complication by avoiding injury of the lenticulostriate arteries (LSA).

[Adenoid cystic carcinoma with striking intracranial extension: a case report].

We report a case of intracranial adenoid cystic carcinoma in the middle cranial fossa. A 40-year-old woman had noticed a tumor in the left external auditory canal 8 years previously. It was totally resected at that time. Histologically, the tumor was diagnosed as an adenoid cystic carcinoma. Recently the patient presented with loss of consciousness, suffering from mild recent-memory disturbance. Neurological examination revealed no other abnormalities. Magnetic resonance imaging (MRI) demonstrated an enhanced solid mass with a multicystic component in the left temporal lobe. She underwent subtotal removal of the tumor. It was well-demarcated, and was confirmed to be adhesive to the dura matter of the middle cranial fossa. Histology of the tumor was the same as it was 8 years ago. She was discharged from our hospital without neurological deficits. Two months after surgery, gamma knife radiosurgery was performed against the residual tumor.

[Growth of asymptomatic unruptured aneurysms in follow-up study: report of three cases].

The natural history of asymptomatic unruptured aneurysms that have not been subjected to surgery was studied radiologically using MRA and MRI and 3D-CT angiography (3D-CTA) commencing in 1993. We report on the growth of documented asymptomatic unruptured aneurysms in three patients. Growth of the aneurysms was followed by repeated MRA, MRI and 3D-CTA. In Case 1, a 71-year-old woman had been diagnosed as having a 3 mm unruptured anterior communicating artery aneurysm. The size of the aneurysm had expanded to 4 mm, 2 years later. This was detected during a follow-up MRA and confirmed by angiography. After this follow-up MRA, the aneurysm showed no change in size or shape for 8 years. Case 2 was that of a 75-year-old woman who had a 4.5 mm aneurysm involving the basilar artery and the superior cerebellar artery. 12 months later, an MRA was carried out as a follow-up study. This MRA revealed that the aneurysm had developed a bleb and was expanding. 8 months later the patient bled from the aneurysm and underwent surgery, but died. Before surgery, the diameter of the aneurysm, confirmed by angiogram, was 5.5 mm including the bleb. The third patient was a 66-year-old woman who had a 7 mm internal aneurysm involving the carotid artery and the posterior communicating artery. 3 years later a 3D-CTA detected the expansion of the aneurysm and development of an aneurysm bleb. 6 years later more expansion occurred and 3 months after that the patient bled from the aneurysm and underwent clipping. At that time, the diameter of the aneurysm, confirmed by angiography, was 13 mm including the bleb. In this follow-up study, patients with diagnosed asymptomatic unruptured aneurysms were followed up by MRA and MRI and 3D-CTA to determine risk factors for aneurysm rupture. We emphasize the fact that growth of an unruptured aneurysm and formation of blebs are important risk factors of aneurysm rupture.

[Rupture of previously documented asymptomatic unruptured aneurysms--aneurysm size: risk factor for aneurysm rupture].

The natural history of asymptomatic unruptured aneurysms is not clear. We conducted a follow up study of 100 patients (since 1993) with 122 asymptomatic unruptured aneurysms that had not been operated on. We report five patients with previously documented asymptomatic unruptured aneurysms smaller than 10 mm in diameter that subsequently ruptured. Among the 100 patients, five had suffered subarachnoid hemorrhage (SAH) due to rupturing of an aneurysm. Of the 5 cases, 1 was male and 4 were female, with ages ranging from 59-73 years (mean age, 68 years). The aneurysms were on the MCA in 3, on the BA-SCA in 1, on the IC-PC in 1. The maximal diameter of the aneurysms at diagnosis ranged from 4.5 to 8 mm. The period from discovery to SAH was from 4 to 69 months and the cumulative rate of rupture of the aneurysms was 1.5 percent per year. Four of the 5 cases increased in size after the rupture. In our series, 2 of the 5 cases showed enlargement and the development of an aneurysmal bleb in the follow up MRA and 3D-CTA. The present study demonstrates that five asymptomatic unruptured aneurysms less than 10 mm in diameter subsequently ruptured. We ought to seriously consider the assertion published in the New England Journal of Medicine (Dec. 10, 1998), that unruptured aneurysms less than 10 mm in diameter have a very low probability of subsequent rupture.