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ABSTRACT: Inertial force of the bloodstream results in the local elevation of intravascular pressure secondary to flow impact. Previous studies suggest that this "impacting force" and the local pressure elevation at the aneurysm may have a large contribution to the development of cerebral aneurysms. The goal of the present study is to evaluate how the bloodstream impacting force and the local pressure elevation at the aneurysm influences the rupture of cerebral aneurysms.
A total of 29 aneurysms were created in 26 patient-specific vessel models, and computer simulations were used to calculate pressure distributions around the vessel branching points and the aneurysms.
Direct impact of the parent artery bloodstream resulted in local elevation in pressure at branch points, and bends in arteries (231.2+/-198.1 Pa; 100 Pa=0.75 mm Hg). The bloodstream entered into the aneurysm with a decreased velocity after it impacted on the branching points or bends. Thus, the flow impact at the aneurysm occurred usually weakly. At the top or the rupture point of the aneurysm, the flow velocity was always delayed. The local pressure elevation at the aneurysm was 119.3+/-91.2 Pa.
The pressure elevation at the area of flow impact and at the aneurysm constituted only 1% to 2% of the peak intravascular pressure. The results suggest that the bloodstream impacting force and the local pressure elevation at the aneurysm may have less contribution to the rupture of cerebral aneurysms than was expected previously.
Stroke 10/2005; 36(9):1933-8. · 5.73 Impact Factor
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ABSTRACT: Ultra-early surgical treatment in which associated brain injury is minimized and maximal volume of hematoma is removed shortly after onset with secure hemostasis is expected to be established. We developed a transparent guiding sheath and other surgical instruments for endoscopic surgery and established a novel, ultra-early stage surgical procedure using those instruments. This procedure has the following characteristics: (a) burr hole opening under local anesthesia is possible; (b) a transparent sheath improves the visualization of the surgical field in the parenchyma and the hematoma; (c) free-hand surgery without fixing an endoscope and a sheath to a frame facilitates three-dimensional operation; (d) secure hemostasis by electric coagulation is possible; (e) relatively simple surgical instruments are easy to prepare. We have performed this procedure in 82 patients with intracerebral or intraventricular hemorrhage (44 with putaminal hemorrhage, 12 with thalamic hemorrhage, 8 with subcortical hemorrhage, 8 with cerebellar hemorrhage, 10 with intraventricular hemorrhage). Twenty-four of those patients received our treatment in the ultra-early stage (within 3 hours after onset). The mean duration of surgery was 63 minutes, the mean hematoma reduction rate was 96%, and no peri-operative hemorrhage with deterioration of symptoms and/or signs occurred. Therefore, we believe that endoscopic hematoma evacuation with our surgical procedure is a promising ultra-early stage treatment for intracerebral hemorrhage and that it may improve the long-term prognosis in patents with intracerebral hemorrhage.
Neurocritical Care 02/2005; 2(1):67-74. · 2.47 Impact Factor
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ABSTRACT: The head-shaking method combined with cisternal irrigation has been proposed to be effective in preventing cerebral vasospasm after subarachnoid hemorrhage (SAH) by facilitating rapid washout of the clot from the subarachnoid space. This study was conducted to evaluate the effectiveness of this method.
The inclusion criteria included the following: 1) Fisher Grade 3 SAH on admission computerized tomography (CT) scans; 2) aneurysm secured within 48 hours of SAH onset; and 3) no focal deficit and ability to obey commands within 24 hours postsurgery. Two hundred thirty patients treated between 1994 and 2002 fulfilled the criteria. Because only one machine was available and it required I month of maintenance every other month, 114 patients underwent irrigation combined with the head-shaking method (head-shaking group), whereas the remaining 116 patients received cisternal irrigation alone (control group). There were no significant differences in sex, age, site of aneurysm, or preoperative grade between the two groups. The incidence of symptomatic vasospasm with or without infarction, cerebral infarction on CT scans, and permanent ischemic neurological deficit was 25.7, 17.7, and 8.8%, respectively, in the control group and 15.2, 4.5, and 2.7% in the head-shaking group. The difference was statistically significant for symptomatic vasospasm, cerebral infarction, and permanent ischemic neurological deficit (p < 0.05). In a multivariate backward stepwise logistic regression analysis, absence of head shaking was the only variable that was predictive of permanent ischemic neurological deficit (p = 0.061). The outcomes evaluated using the modified Rankin Scale were better in the head-shaking group (p = 0.051).
The head-shaking method significantly reduced the incidence of symptomatic vasospasm, cerebral infarction, and permanent ischemic neurological deficit and improved the clinical outcomes in patients who underwent cisternal irrigation therapy after aneurysmal SAH.
Journal of Neurosurgery 03/2004; 100(2):236-43. · 2.96 Impact Factor
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Nō to shinkei = Brain and nerve 07/2003; 55(6):499-508.
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Journal of Neurosurgery 06/2003; 98(5):1144-5; author reply 1145-6. · 2.96 Impact Factor
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Journal of Neurosurgery 06/2003; 98(5):1134. · 2.96 Impact Factor
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ABSTRACT: We have characterised the blood vessels found in normal cerebral vasculature and in arteriovenous malformations (AVMs), based on the expression of smooth muscle cell (SMC)-specific proteins. The marker proteins used were smooth muscle alpha-actin and four myosin heavy chain isoforms (SM1, SM2, SMemb and NMHC-A). Specimens of AVM obtained during surgery, and normal cerebral vessels from autopsy cases were studied immunohistochemically and compared. The arterial components of AVM contained an abundance of SMCs of the contractile phenotype, which were positive for alpha-actin, SM1 and SM2, but not for SMemb and NMHC-A. These components showed the same staining pattern as mature normal arteries. Two different types of abnormal veins were found in the AVM specimens: large veins with a thick and fibrous wall (so-called 'arterialised' veins) and intraparenchymal thin-walled sinusoidal veins. The former expressed alpha-actin, SM1, SM2, and SMemb, the latter expressed alpha-actin, SM1, and SM2. These marker expression patterns resembled those of normal cerebral arteries, and the results were compatible with arterialisation of the cerebral veins caused by arteriovenous shunting. However, the expression of SMemb was found only in the arterialised type of veins, not in the sinusoidal type or the arteries that had sustained abnormal blood flow in the AVMs. The thick-walled veins in the AVMs showed the same staining pattern as normal veins of dural plexus origin (large subarachnoid veins and dural sinuses). It is therefore possible to assume that they originated from the dural plexus, and extended into the brain during the formation of AVMs.
Acta Neuropathologica 06/2003; 105(5):455-61. · 9.32 Impact Factor
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ABSTRACT: We report a case of a bilateral vertebral dissecting aneurysm associated with subarachnoid hemorrhage. Proximal ligation of the vertebral artery on the ruptured side combined with wrapping of the contralateral dissection failed to prevent fatal rebleeding. Since enlargement of the contralateral dissection was observed by postoperative angiography, rupture of the growing contralateral dissecting aneurysm may have caused rebleeding. Hemodynamic changes following the occlusion of one vertebral artery might have led to enlargement and subsequent rupture of the contralateral dissection. Direct wrapping was unable to prevent enlargement of the dissection, so radical surgery including bilateral vertebral artery occlusion combined with vascular reconstruction may be the treatment of choice for this type of lesion.
No shinkei geka. Neurological surgery 04/2002; 30(3):321-5. · 0.13 Impact Factor
