Ryusui Tanaka

Basic Fibroblast Growth Factor Increases Regional Cerebral Blood Flow and Reduces Infarct Size After Experimental Ischemia in a Rat Model

BACKGROUND AND PURPOSE The aim of this study was to ascertain whether basic fibroblast growth factors (bFGF) caused reduction in size of cerebral infarcts in Sprague-Dawley rats with experimental ischemia. METHODS In the first experiment we induced permanent occlusion of the left middle cerebral artery (MCA). Within 5 minutes after MCA occlusion, we infused bFGF (100 ng in 0.1 mL of saline) in the bFGF-treated group (n = 14) and 0.1 mL of saline alone in the control group (n = 7) into the common carotid artery ipsilateral to MCA occlusion. We harvested the brains 24 hours after MCA occlusion and determined infarct size planimetrically as a percentage of hemisphere size. In the second experiment cerebral blood flow (CBF) was continuously measured for 120 minutes after MCA occlusion in the bFGF-treated group (n = 9) and in the control group (n = 8) with the use of laser-Doppler flowmetry. RESULTS Infarct size in the bFGF-treated group decreased significantly in comparison with that in the control group (repeated-measures ANOVA, P < .0001). CBF in the transitional areas between the MCA and the anterior cerebral artery significantly increased in the bFGF-treated group in comparison with that in the control group (repeated-measures ANOVA, P < .005). An approximate 58% decrease in infarct size and a 40% increase in regional CBF were seen on bFGF treatment. CONCLUSIONS The present study suggested that intracarotid administration of bFGF (100 ng) can reduce infarct size after MCA occlusion. It was speculated that the increased CBF in the penumbral areas of MCA may contribute to contraction of infarct size.

A source of haemorrhage in adult patients with moyamoya disease: The significance of tributaries from the choroidal artery

SummaryThis study concerns 19 patients over 16 years of age with Moyamoya disease. Ten cases of intracranial haemorrhage, as the initial haemorrhagic event in patients aged from 21 to 55 (haemorrhagic group) and 9 cases of ischaemic events in 18- to 53-year-old patients (ischaemic group) were included. All haemorrhages were associated with intraventricular haemorrhages (IVH); and all but one case of thalamic haemorrhage were thought to be primary IVH (2 cases of small paraventricular haemorrhage; 2 of small haemorrhages in the splenium; 5 with no intracerebral haematoma). In the 9 patients of the ischaemic group, there were 2 cases of transient ischaemic attacks and 7 of cerebral infarction. Angiographic evaluations demonstrated that the abnormal basal vessel formation and the collateral supplies from the external carotid arteries were poorly developed in both groups. In contrast, the collateral circulation via the choroidal and posterior pericallosal arteries was well demonstrated. Furthermore, marked enlargement of the choroidal arteries and the medullary arteries derived from them was seen more frequently in the haemorrhagic group. These findings suggested that the haemodynamic load in the vessels supplying the walls of the posterior parts of the ventricles and the periventricular region was increased, especially in the haemorrhagic group. Those vessels were considered to be important sites of IVH in adult patients with Moyamoya disase.

Anatomic dissection and classic three-dimensional documentation: a unit of education for neurosurgical anatomy revisited.

OBJECTIVE AND IMPORTANCE:Despite development of computer-assisted neurosurgical navigation, learning by dissecting anatomic specimens is still important. CLINICAL PRESENTATION:We describe the processes from preparation of specimens for cranial dissection to documentation of three-dimensional (3-D) stereoscopic pictures, particularly focusing on the latter, which has been initiated in the Microneuroanatomy Laboratory, Department of Neurological Surgery, University of Florida. INTERVENTION:Preparation consists of irrigation of the major vessels and injection of colored silicone. The 3-D documentation, obtaining two pictures corresponding to each eyes view, is obtained by the shoot-shift-shoot method using a single camera mounted on a slide bar. The key of this method is correct shifting of the camera without alignment error to get exact 3-D effects. Observation of 3-D image can be made with free viewing, a 3-D viewer, or projection. Tips concerning all of the processes involved are described. CONCLUSION:The presented method of dissection and obtaining 3-D images is beneficial for accomplishing studies of anatomy and for providing teaching method.

Draining vein pressure increases and hemorrhage in patients with arteriovenous malformation.

BACKGROUND Recent radiological studies have shown that arteriovenous malformations with impaired venous drainage may be susceptible to hemorrhage. To evaluate this hypothesis using a hemodynamic approach, we measured intravascular pressure during surgery in three patients with arteriovenous malformation. SUMMARY OF REPORT In three patients we measured intravascular pressures in the draining venous system and the feeding arteries simultaneously before removal of arteriovenous malformations with marked segmental stenotic or occlusive draining veins and evidence of hemorrhage. The draining vein pressures at prestenotic (or preocclusive) sites in the three patients were 38, 25, and 40 mm Hg, respectively, all significantly above the normal cortical venous pressure, whereas pressure measurements in poststenotic sites and the sagittal sinus pressure in the venous drainage system approached normal values. The feeding artery pressures in the patients were lower than normal cortical artery pressure because of the arteriovenous shunt. CONCLUSIONS Intraoperative vascular pressure measurements support the hypothesis that arteriovenous malformations with impaired venous drainage may be associated with a local increase in venous pressure and thus may be susceptible to hemorrhage.

Dural-Pial Arteriovenous Malformation After Sinus Thrombosis

BACKGROUND We report an unusual case of acquired dural-pial arteriovenous malformation (AVM) following sinus thrombosis. CASE DESCRIPTION Initial angiography performed in a 39-year-old man showed thrombosis of the superior sagittal sinus (SSS) and the right transverse sinus (TS) but no vascular malformations. Follow-up angiography 29 months later revealed recanalization of the SSS and the TS, retrograde cortical venous drainage which suggested that thrombosis of the sinuses probably propagated into the adjacent parietal cortical veins, and development of a dural-pial AVM at or near the site of thrombi in more than one cortical vein. Complete surgical excision of the lesion was accomplished without neurological deterioration. CONCLUSIONS The present case suggests the possibility that the pial AVM is not only a congenital condition but also may develop as an acquired lesion.

The effect of encephalo-myo-synangiosis on abnormal collateral vessels in childhood Moyamoya disease

Abstract Child patients with Moyamoya disease initially present with ischemic symptoms. However, the long-term risk of intracranial hemorrhage for childhood Moyamoya disease is unknown. Hemodynamic overload to the fragile collateral vessels has been considered to cause hemorrhage. We reviewed angiograms to evaluate the effect of encephalo-myo-synangiosis (EMS) on abnormally dilated collateral vessels in 13 child patients with Moyamoya disease. EMS was performed on 24 sides in 13 patients ranging from 5 to 14 years of age. Post-operative angiography (6-88 months after surgery) revealed good revascularizations through EMS (larger than one-third of the middle cerebral artery (MCA) distribution) in 18 sides (75%) and smaller revascularizations in 6 sides (25%). In cases with a good revascularization through EMS, reduction of the abnormal collateral vessels was observed not only in the basal Moyamoya vessels (94% of sides) but also in the medullary arteries derived from the choroidal arteries (62% of sides), which are considered to cause intraventricular hemorrhages in adult patients. It is suggested that EMS may reduce the hemodynamic load on dilated collateral vessels and, subsequently, the long-term risk of intracranial hemorrhage in childhood Moyamoya disease. [Neurol Res 2000; 22: 341-346]

Correlation between intravascular pressure and risk of hemorrhage due to arteriovenous malformations

The correlation between intraoperative pressure levels measured in the feeding arteries and in the draining veins, and the risk of hemorrhage from arteriovenous malformations (AVMs) is discussed. Feeding artery pressure (FAP) was significantly higher in AVMs with hemorrhage (57 +/- 11 mmHg) than in AVMs without hemorrhage (38 +/- 4), and draining vein pressure (DVP) in the former (24 +/- 5) was significantly higher than that in the latter (13 +/- 5). FAP and DVP were inversely related to the number of draining veins and size of the AVMs. The present study suggests that a high FAP and a high DVP may contribute to the development of hemorrhage from AVMs, and supports previous reports that small AVMs and AVMs with only one draining vein are susceptible to hemorrhage.

Can proximity of the occipital artery to the greater occipital nerve act as a cause of idiopathic greater occipital neuralgia? An anatomical and histological evaluation of the artery-nerve relationship.

Background: The purpose of this study was to clarify whether proximity of the occipital artery to the greater occipital nerve can act as a cause of occipital neuralgia, analogous to the contribution of intracranial vessels due to compression in cranial nerve neuralgias, represented by trigeminal neuralgias due to compression of the trigeminal nerve root by adjacent arterial loops. Methods: Twenty-four suboccipital areas in cadaver heads were studied for anatomical relationships between the occipital artery and the greater occipital nerve, with histopathological assessment of the greater occipital nerve for signs of mechanical damage. Results: The occipital artery and greater occipital nerve were found to cross each other in the nuchal subcutaneous layer, and the latter was constantly situated superficial to the former at the cross point. An indentation of the greater occipital nerve due to the occipital artery was observed at the cross point in all specimens. However, histopathological examination did not reveal any findings of damage to nerves, even in specimens with atherosclerosis of the occipital artery. Conclusions: Although the present study did not provide direct evidence that the occipital artery contributes to occipital neuralgia at the point of contact with the greater occipital nerve, the possibility still cannot be precluded, because the occipital artery may be palpable in areas corresponding to tenderness of the greater occipital nerve. Further studies, including clinical cases, are needed to clarify this issue.

Vascular structure of arteriovenous malformations

Cerebral arteriovenous malformations (AVMs) are classified angiographically into two types: the arteriovenous fistula (AVF) type and the plexiform type. However, the differences in vascular structure of these two types have not been clarified. The purpose of the present study is to elucidate the vascular structure of plexiform AVMs and to discuss the clinical significance of this classification of AVMs. Specimens of AVMs resected in 8 cases and identified by cerebral angiography as plexiform AVMs were examined. Immediately after their removal, microdissection of the terminal arterial feeder, the nidus, and the venous drainer was performed under a microscope. A histological examination of each element was then conducted. Microdissection of a portion of the vascular mass that formed the nidus made it possible to separate individual vessels of the mass from each other. Many of these individual vessels connected with the feeder on one side, while the other side anastomosed with the drainer, thus exhibiting the morphology of an AVF. From our examination of the AVMs in the present study, we inferred that the plexiform type is fundamentally a conglomeration of AVFs. It is therefore suggested that the vascular structure of this type of AVM is not fundamentally different from that of the AVF type.

The Influence of Vascular Pressure and Angiographic Characteristics on Haemorrhage from Arteriovenous Malformations

Summary¶ Background. The present study was designed to determine whether there is a physiological explanation for the predisposition of patients with certain angiographic characteristics to haemorrhage from cerebral arteriovenous malformations (AVMs). Methods. Intra-operative measurement of feeding artery pressure (FAP) and intravascular pressures in the draining venous system [draining vein pressure (DVP) and cranial sinus pressure (SP)] were performed for 30 AVM cases using direct puncture of the vessels. The correlation between pressures and previously described angiographic characteristics predisposing to haemorrhage were evaluated. Findings. Small nidus size and only one draining vein increased the risk of haemorrhage. FAP and DVP are both inversely related to the number of draining veins and the size of the AVMs. DVP was significantly higher in AVMs with haemorrhage (23.1±8.7 mmHg) than in those without (13.5±4.4), as was FAP (58.6±12.8 as opposed to 38.7±4.7) (p<0.05). Moreover, the difference between systemic blood pressure and the FAP with haemorrhagic AVMs (17.0±9.5 mmHg) was significantly lower than that in nonhaemorrhagic cases (33.7±5.5) (p<0.05). The pressure difference between the feeding artery and draining vein was not significant between the haemorrhagic and nonhaemorrhagic groups. There was no significant difference of SP between haemorrhagic and nonhaemorrhagic patients. Interpretation. The present study suggests that a high DVP probably induced by high resistance in the venous drainage system, as well as a high FAP, may contribute to the development of haemorrhage from AVMs, and physiologically supports previous reports that small AVMs and AVMs with only one draining vein are susceptible to haemorrhage.