Michiharu Nishijima

Vasa vasorum of the intracranial arteries.

SummaryMost of the major extracranial arteries have vasa vasorum which play an important role in some pathological conditions. However, in the intracranial arteries, the existence of vasa vasorum and their pathological implication have not been adequately investigated. We examined the distribution and incidence of vasa vasorum in the major cerebral arteries and their relationships to certain clinical factors in 50 autopsy cases performed between 1987 and 1994. By light microscopy, vasa vasorum were found in 36 of 50 patients. Of 36 patients, vasa vasorum in 30 cases were localizedly observed in the tunica adventitia and the in other 6 were distributed in the tunica media accompanied by intramural haemorrhage. Existence of vasa vasorum was more common in the proximal arteries (vertebral, internal carotid, and basilar arteries) than in the distal arteries (middle cerebral and anterior cerebral arteries). Vasa vasorum were found more frequently in aged patients with severe atherosclerosis and those with cerebrovascular diseases. Our results indicated that intracranial vasa vasorum existed with a higher frequency in the tunica adventitia of the vertebral and internal cerebral arteries, and the incidence of vasa vasorum related to severity of atherosclerosis. The development of vasa vasorum in the tunica media may reflect some pathological changes of cerebral arteries.

Distinctive flow pattern of wall shear stress and oscillatory shear index: similarity and dissimilarity in ruptured and unruptured cerebral aneurysm blebs

OBJECT The difference in the hemodynamics of wall shear stress (WSS) and oscillatory shear index (OSI) between ruptured and unruptured aneurysms is not well understood. The authors investigated the hemodynamic similarities and dissimilarities in ruptured and thin-walled unruptured aneurysm blebs. METHODS Magnetic resonance imaging-based fluid dynamics analysis was used to calculate WSS and OSI, and hemodynamic and intraoperative findings were compared. The authors also compared ruptured and unruptured thin-walled blebs for the magnitude of WSS and OSI. RESULTS Intraoperatively, 13 ruptured and 139 thin-walled unruptured aneurysm blebs were identified. Twelve of the ruptured (92.3%) and 124 of the unruptured blebs (89.2%) manifested low WSS and high OSI. The degree of WSS was significantly lower in ruptured (0.49 ± 0.12 Pa) than in unruptured (0.64 ± 0.15 Pa; p < 0.01) blebs. CONCLUSIONS Ruptured and unruptured blebs shared a distinctive pattern of low WSS and high OSI. The degree of WSS at the rupture site was significantly lower than in the unruptured thin-walled blebs.

Acute pathologic features with angiographic correlates of the nearly or completely occuluded lesions of the cervical internal carotid artery

BACKGROUND The true pathologic process of nearly or completely occluded lesions of the cervical internal carotid artery (ICA) has not been studied sufficiently. This information is important in determining the critical indications for endarterectomy. METHODS Acute pathologic features of these advanced occlusive lesions of the ICA were studied in 40 patients who underwent emergency carotid endarterectomy. Gross morphologic and histopathologic features of these occlusive lesions were examined, and the relationship between the clinical information and the pathologic characteristics was investigated. RESULTS Thirty-seven lesions had histologic features of advanced atherosclerosis complicated by fresh intraplaque hemorrhages with or without transintimal extension. Thinwalled neovessels were thought to be an important etiologic factor in producing intraplaque hemorrhage. The remaining three lesions without these changes had strangulated embolic material at the occluded portion. A good correlation between these pathologic features and angiographic findings was found. CONCLUSION The presented results clearly indicate that intraplaque hemorrhage is the most important factor in producing and determining the acute pathologic features of symptomatic and advanced atheromatous occlusive ICA lesions.

Spontaneous occlusion of traumatic carotid cavernous fistula after orbital venography

A 50-year-old man was admitted to our hospital with a diagnosis of traumatic carotid cavernous fistula. The fistula was observed to disappear spontaneously just after orbital venography. This was confirmed by clinical examinations and subsequent carotid angiogram. The possible mechanisms responsible for the spontaneous occlusion of carotid cavernous fistula are discussed.

Lipophilic fraction of Panax ginseng induces neuronal differentiation of PC12 cells and promotes neuronal survival of rat cortical neurons by protein kinase C dependent manner

Panax ginseng is a traditional Chinese herb with a wide range of therapeutic benefits. Recent studies focusing on its effect on the central nervous system have revealed that ginseng has neurotrophic effects including differentiation of neurons. However, most studies involve use of the water-soluble fraction called saponin, and little is known about the effect of the lipophilic fraction. In the present study, we have shown that the lipophilic fraction of ginseng at a concentration of between 0.1 and 50 microg/ml can induce neurite outgrowth of PC12 cells in a dose-dependent manner. Nearly all cells showed morphological differentiation in response to the lipophilic fraction. This morphological differentiation of PC12 cells appeared to be similar to that of NGF. The lipophilic fraction of ginseng also induced neurite extension and promoted survival of rat cortical neurons at a concentration of between 0.025 and 1 microg/ml. These neurotrophic effects on PC12 cells and cortical neurons were not inhibited by K252b, which selectively blocks neurotrophin actions by inhibiting trk-type receptor tyrosine phosphorylation. This suggests that trks do not participate in the neurotrophic action of the lipophilic fraction. However, the effects were completely attenuated by sphingosine, polymyxin B or staurosporin, known inhibitors of protein kinase C (PKC) and calmodulin-dependent kinases. Our results suggest that the lipophilic fraction of ginseng exerts its neurotrophic effects via PKC-dependent pathways.

Dural arteriovenous fistulae involving the transverse-sigmoid sinus and foramen magnum

The authors present a rare case of dural arteriovenous fistulae (AVFs) involving both the transverse-sigmoid sinus and the foramen magnum, which was treated successfully with multi-staged endovascular procedures. The transverse-sigmoid sinus, which was thrombosed proximally and distally, was occluded by transarterial embolization followed by intraoperative embolization of the sinus using platinum coils. The dural AVF involving the foramen magnum was occluded via a transvenous approach.

Operative correction of a kinked duplicate origin of the vertebral artery in a patient with dizziness. Case report

A 70-year-old woman was admitted to our hospital with complaints of severe dizziness and occipital headache. A right vertebral angiogram demonstrated a kinked, duplicated origin of the vertebral artery. Medical treatment was not effective, and an operative correction was attempted to improve the vertebral artery circulatory flow. The duplicate origin of the vertebral artery was confirmed at the time of surgery. Eight cases of duplicate origin of the vertebral artery in the literature are reviewed.

Computed tomographic findings of good prognosis for hemiplegia in hypertensive putaminal hemorrhage.

Computed tomography (CT) findings were analyzed in 17 patients with hypertensive putaminal hemorrhage accompanied by hemiplegia which had subsided almost completely by conservative therapy within one month after the onset. In such patients a high density area was not seen at the level of the lateral ventricles on CT scan. To study the reason for this, the relationship between the extent of a hematoma and the level at which the pyramidal tract was destroyed was investigated. From consideration of the process of destruction of the pyramidal tract by a hematoma, it seemed that CT findings at the level of the bodies of the lateral ventricles, rather than at the level of the posterior limb of the internal capsule, were of value in evaluating the prognosis of hemiplegia in putaminal hemorrhage.

An experimental model of symptomatic vasospasm induced by oxyhemoglobin in rabbits.

Background and Purpose There are many experimental models for studies of cerebral vasospasm. However, no ideal model has been established thus far to comparatively reproduce the ischemic state of the brain that may occur in patients after subarachnoid hemorrhage. Methods In the present study, we attempted to induce severe vasospasm in rabbits by using an oxyhemoglobin-rich blood product prepared from hemoryzed arterial blood and evaluate neurological symptoms, cerebral angiogram, cerebral blood flow, and histology. Results Clinically significant neurological symptoms were observed in about half of the rabbits. There was no significant correlation between angiographic results of the vasospastic state of the main artery and the severity of neurological symptoms observed. However, the cerebral blood flow was significantly lower than in the control group and significantly correlated with the severity of neurological symptoms. On histological examination, lesions were found in about half of the rabbits. Development of obvious infarction was found more frequently than in other reported models. Conclusions These results suggest that this model is appropriate as an experimental model of vasospasm occurring after subarachnoid hemorrhage and is especially useful in that it induces vasospasm intense enough to cause obvious infarction.

Platelet-activating factor (PAF) and the development of chronic subdural haematoma

SummaryPlatelet activating factor (PAF) content and PAF-acetylhydrolase (PAFAH) activity were measured in the plasma and haematoma of 34 chronic subdural haematoma (CSH) patients. The plasma PAF level in patients with CSH was higher than that in healthy controls. Although there was no correlation between the plasma PAF levels and the interval between the onset of symptoms and the day of sampling, namely, the interval after bleeding, the haematoma PAF level gradually decreased according to the interval after the onset of symptoms. There was no difference between plasma PAFAH activity in patients with CSH and that in healthy controls, and haematoma enzyme activity gradually increased correlated with the interval between the onset of symptoms and surgery. In addition, the localization of PAF in haematoma capsules was histochemically determined. PAF was solely localized to the peri-sinusoidal vessels in the outer membrane of haematoma capsules. Based on these biochemical and histochemical studies, we speculated that PAF may play a role in the development of chronic subdural haematomas.