Stroke; a journal of cerebral circulation
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Calcium channel blockers reduce edema due to cerebral ischemia, but little is known about their usefulness in hemorrhage. Therefore, we studied the effect of the calcium channel blocker (S)-emopamil in collagenase-induced hemorrhage. ⋯ Early administration of (S)-emopamil is beneficial in hemorrhagic lesions, but a subsequent delayed injection may be deleterious. Knowledge of the time of hemorrhage will be important in use of these agents in treating hemorrhage.
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This study validates transcranial Doppler sonography (TCD) for determination of the lower limit of cerebral blood flow (CBF) autoregulation and establishes a relation between global CBF and mean flow velocity (Vmean) in the middle cerebral artery. ⋯ TCD is valid for determination of the lower limit of CBF autoregulation, and changes in CBF may be reliably evaluated by TCD during changes in cerebral perfusion pressure in normal subjects.
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The purpose of this study was to evaluate the use of velocity criteria applied to transcranial Doppler (TCD) signals in the detection of stenosis of the middle cerebral (MCA), distal vertebral, and basilar arteries. ⋯ TCD may be an effective screening test for M1 stenosis when velocity criteria alone are used. TCD may less reliably detect intracranial vertebral and basilar artery stenosis.
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Beneficial effects of calcium antagonists in cerebral ischemia and trauma have been attributed in part to improved cerebral blood flow. Enhancement of cerebral blood flow, however, could aggravate the pathological situation if brain injury is associated with intracerebral hemorrhage. In this study we used high-field magnetic resonance imaging in an animal model of intracerebral hemorrhage to determine noninvasively the effect of the calcium and serotonin antagonist levemopamil [international nonproprietary name for (S)-emopamil] when infused in a dose (6 mg/kg) that is known to increase cerebral blood flow. ⋯ Aggravation of intracerebral hemorrhage was not observed by magnetic resonance imaging in levemopamil-infused animals. However, infusion of heparin caused a significant (P < .05), almost twofold increase in the size of intracerebral hemorrhage. These results justify clinical trials with levemopamil in cerebral disorders such as stroke, brain trauma, and peritumoral brain edema, which may be accompanied by intracerebral hemorrhage from the beginning or where transition to intracerebral hemorrhage may occur.
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Comparative Study
Blood flow velocity and vasomotor reactivity in patients with arteriovenous malformations. A transcranial Doppler study.
A large percentage of patients with a cerebral arteriovenous malformation (AVM) show focal neurological signs or have a history of intracranial hemorrhage. The present study used transcranial Doppler sonography to assess the clinical significance of hemodynamic disturbances in the intracranial arteries of patients with an AVM. ⋯ Our results suggest two distinct relations between transcranial Doppler results and clinical findings: (1) Relatively normal vasomotor reactivity values in arteries ipsilateral to an AVM indicate a high-pressure AVM with an increased risk of hemorrhage. (2) A strongly pathological vasomotor reactivity in arteries ipsilateral and contralateral to an AVM indicates a low-pressure AVM with a higher prevalence of hemodynamically induced neurological signs.