Cerebral vascular disease and behavior. I. The syndrome of the mesencephalic artery (basilar artery bifurcation).
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An 85-year-old man who did not have any previous history of heart disease was admitted to our hospital with the chief complaints of disturbance of consciousness, tetraparesis, and bilateral Babinski signs. On admission, intravenous digital subtraction angiography (DSA) showed bilatral vertebral arteries without filling the basilar artery. On the second hospital day, MRI showed a septum in the basilar artery, and no infarctions were noted in the brain stem. He gradually improved with heparin therapy. On the tenth hospital day, intravenous DSA disclosed filling of the basilar artery. On the sixteenth hospital day, conventional cerebral angiography revealed filling of the basilar artery from the left vertebral artery, and string sign and linear shadow (intimal flap) was noted in the basilar artery. He was diagnosed to have the basilar artery dissection. The patient became ambulatory and was discharged independently. This is very rare case of the basilar artery dissection with a good prognosis.
We studied Pourcelot's index (PI), which shows cerebral vascular resistance, in the anterior cerebral arteries and basilar artery, and the PI ratio (Pourcelot's index in the anterior cerebral artery/Pourcelot's index in the basilar artery) in 11 measurements of hydrocephalus. The mean values of PI in the anterior cerebral artery, basilar artery, and the PI ratio before treatment were significantly higher than those after treatment and those in normal infants. Before treatment, the mean PI in the anterior cerebral arteries was significantly higher than the mean PI in the basilar artery. All PI ratios increased to 1.00 or more. After treatment and in normal infants, the mean PI in the anterior cerebral arteries was significantly lower than the mean PI in the basilar artery. All PI ratios decreased to less than 1.00. We believe that the PI ratio is useful to evaluate the need or effect of treatment in hydrocephalus.
Basilar trunk saccular aneurysms associated with fenestration are infrequent, especially in the middle or distal portion of the basilar artery. Surgical treatment of the basilar trunk aneurysm is difficult, due to its anatomical environment and the complicated surgical exposure. A 46-year-old woman presenting with Hunt and Kosnik grade II subarachnoid hemorrhage was found to have a ruptured aneurysm arising at the proximal corner of the associated fenestration in the middle portion of the basilar artery. Because of surgical difficulties anticipated in approaching the aneurysm, it was decided to treat it with endovascular embolization utilizing the Guglielmi detachable coil; and complete occlusion of the aneurysm was obtained. The efficacy of endovascular treatment for the basilar trunk aneurysm with associated fenestration is discussed from anatomical and embryological points of view, and relevant literature is reviewed.
Two patients with giant aneurysms of the basilar artery treated with prophylactic extracranial-intracranial arterial bypass (EIAB) to the rostral brain stem before basilar artery ligation are presented. In both cases, the bypass provided considerable collateral flow to the upper basilar, posterior cerebral, and superior cerebellar arteries. Basilar artery ligation has been shown to be an effective, albeit dangerous, means of treating giant aneurysms of the basilar artery. The risk of significant brain stem ischemia after ligation is at least 30%. EIAB to the rostral brain stem should be considered whenever basilar artery ligation is performed, especially in cases where angiography demonstrates poor collateral circulation to the distal basilar artery.
Basilar artery (BA) aplasia when unaccompanied by a primitive carotid-vertebrobasilar anastomosis is exceedingly rare. The association of BA aplasia with two aneurysms on the dominant posterior communicating artery (PCoA) has not been previously reported. This 40-year-old man presented in a state of drowsiness and responded to simple commands only after being coaxed. He had complete left cranial third nerve palsy, right hemiparesis, and persisting signs of meningeal irritation. A computerized tomography (CT) scan revealed subarachnoid and intraventricular hemorrhage. An angiogram revealed BA aplasia. The right PCoA followed a sinuous course with multiple loops and provided the dominant supply to the posterior circulation. This vessel harbored two aneurysms, one at the origin of the PCoA from the internal carotid artery and the other at the looping segment just proximal to the brainstem. The left PCoA was extremely thin. The pterional transsylvian approach was used to clip the two aneurysms on the PCoA. The hemodynamic changes produced by the BA aplasia may have produced alterations in the cerebral vasculature leading to aneurysm formation and consequent subarachnoid hemorrhage.
Using the neck rotation test during examination of Doppler's blood flows in vertebral arteries and basilar artery, the authors examined 60 subjects aged 16-60 years, including 20 healthy ones and 40 with cervical spondylarthrosis. The Transpect-TCD was used. Half the patients with cervical spine changes had also receptive hearing damage of low degree. The study demonstrated that neck rotation affected of patological Doppler's blood flows in one or in both vertebral arteries at 50% patients with cervical spondylarthrosis, but without clinical symptoms, and at 70% patients with cervical spondylarthrosis and clinical symptoms. The neck rotation test can have diagnostic significance by examination of sufficiency in vertebrobasilar system, or qualitative significance to microsurgical treatment.
The anatomical and physiological differences between the carotid and vertebrobasilar circulations suggest the possibility of a different response to variations in systemic pO2. We evaluated cerebrovascular response (CR) in these two systems by monitoring variations in the blood flow velocities in the middle cerebral and basilar arteries during hypoxia. Eighteen healthy, non-smoking volunteers underwent transcranial Doppler study during a state of hypoxia obtained by means of the rebreathing method. Oxyhaemoglobin saturation (SaO2) was monitored using a pulsoxymeter in the 88-94% range. The cerebral blood flow velocity (BFV) was measured in the right middle cerebral artery (MCA) and the basilar artery (BA). Our findings indicate that the mean blood flow velocity (MFV) in the BA changes at a lower rate than that in the MCA during hypoxia.
The authors describe a technique for mobilization of the internal carotid artery (ICA) for basilar artery (BA) aneurysm surgery. Using the epidural approach, the anterior clinoid process, orbital roof, and optic canal are drilled away. The ICA is made mobile to the C3 segment by cutting the dural ring and dissecting the ICA from the carotid groove. The ophthalmic artery is then dissected from the optic canal. This mobilization of the ICA secures wide operative fields on both its medial and lateral sides and permits complete clipping of BA aneurysms.
We studied the value of Pourcelot's index of resistance in the anterior cerebral arteries (RI-ACA) and basilar artery (RI-BA) in 69 measurements of term infants on days 1, 5, 10, 15, 20, 30 and 60. The mean value of RI-ACA (0.723 +/- 0.038, +/- SD) was significantly lower than that of RI-BA (0.750 +/- 0.041) (p less than 0.001). RI-ACA values were higher than RI-BAs in only five measurements (7.2%). The values of RI-ACA and RI-BA decreased from the first day to the fifth day of life. They increased continuously and showed their highest values on the day 15. After the 15th day, they decreased mildly again. The values of RI ratio (= RI-ACA/RI-BA) were stable (0.96-0.97).
We made 10 measurements of Pourcelot's index of resistance (RI) in the anterior cerebral artery (RI-ACA) and basilar artery (RI-BA), and RI ratio (= RI-ACA/RI-BA) in seven cases of hydrocephalus before and after treatment. The mean values of RI-ACA (0.831 +/- 0.050, mean +/- SD), RI-BA (0.800 +/- 0.053) and RI ratio (1.039 +/- 0.030) before treatment were significantly higher than in normal infants. Two hours after treatment, the mean RI-ACA (0.654 +/- 0.099) was lower than in normal infants, and RI-BA (0.684 +/- 0.101) were normalized. Before treatment, the mean value of RI-ACA was higher than that of RI-BA. All RI ratios were higher than 1.00. After treatment, the mean RI-ACA was lower than the mean RI-BA. All RI ratios were normalized and lower than 1.00 (0.957 +/- 0.024).
We studied the values of the Pourcelot's index of resistance in the anterior cerebral artery (RI-ACA) and basilar artery (RI-BA) in very low birth weight infants weighing less than 1,500 g at birth. At the time of measurements, their postconceptional ages were 32, 34, 36, 38, 40 and 42 weeks. The mean value of RI-ACA (0.744 +/- 0.026, +/- SD) was significantly lower than that of RI-BA (0.766 +/- 0.026) (p less than 0.001), and they were higher than those in normal term infants. However, the mean value of RI-ACA and RI-BA, averaged from the measurements of postconceptional ages at 38, 40 and 42 weeks, showed no significant difference from those of normal term infants. In contrast, the mean value of RI ratio (= RI-ACA/RI-BA) in very low birth weight infants showed no significant difference from that of normal term infants.
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To clarify the significance of motor evoked potentials following transcranial magnetic stimulation (MMEPs) in acute stage of cerebral ischemia, MMEPs were recorded in rats with the right middle cerebral artery (MCA) and/or the basilar (BA) artery occlusions. MMEPs from bilateral forelimb muscle and regional cerebral blood flow (rCBF) of the pons were recorded simultaneously. After MCA occlusion, the amplitudes of MMEPs from left forelimb were increased up to approximately 184-221% of the pre-ischemic value for 60 min, though the latencies were unchanged. On the other hand, in the rats of BA occlusion and both BA and MCA occlusion groups, MMEPs amplitudes were decreased to 8-25% of the pre-ischemic value for 60 min. Pontine rCBF was decreased to 28-44% in both groups. As a mechanism of the facilitation of MMEPs after MCA occlusion, the affection of the inhibitory mechanism between the cerebral cortex and the generator of MMEPs by MCA occlusion is speculated.
BACKGROUND: Basilar artery occlusion usually has a very poor outcome and is associated with a high mortality rate. Local intra-arterial thrombolysis may improve the clinical outcome and reduce mortality in the treatment of acute basilar artery occlusion. We evaluated the possible variables affecting recanalization and clinical outcome in patients with basilar artery occlusions undergoing thrombolytic therapy. METHODS: We analyzed retrospectively the clinical course and outcome of a series of 26 patients between 1998 and 2001. All patients who were examined within 24 hours after onset of symptoms underwent emergency cerebral angiography and subsequent intra-arterial thrombolysis. Three patients additionally received percutaneous transluminal angioplasty of underlying stenosis at the site of thrombosis. RESULTS: Outcome was good in 9 patients (34.6%) and poor in 17 (65.4%). Recanalization could be achieved in 24 patients (92.3%) and was not affected by age, sex, site of occlusion, etiology, thrombolytic drugs, or time interval. Good outcome was associated with younger age, good initial clinical condition, and no evidence of brain stem infarction. There was no association between the interval (greater or less than 6 hours) from the onset of symptoms until the end of thrombolysis and survival. CONCLUSIONS: We confirm that intra-arterial thrombolysis reduces mortality in basilar artery occlusion. Young patients (<75 years) without any infarct in brain stem before the start of treatment seem to be the ideal candidates for thrombolysis. Basilar artery thrombosis could and should be reopened, even late (after 6 hours) after symptom onset.
Basilar artery occlusion (BAO) causing brainstem infarction occurred in a 7-year-old boy without any basic disorders. A diagnosis of BAO due to basilar artery dissection (BAD) was suspected at angiography, and this was confirmed by gadolinium-enhanced magnetic resonance imaging (MRI). These investigations clearly showed all the typical diagnostic signs such as a pseudolumen, double lumen and intimal flap, and a pseudolumen in resolution. The spontaneous healing of the dissection was clearly demonstrated during 10 months of follow-up. We stress that BAD can occur in young children and that combined diagnosis with gadolinium-enhanced MRI and angiography is conclusive for diagnosis of dissecting aneurysms. Wider use of these combined diagnostic methods will allow the detection of less severe basilar artery dissection, thus extending the spectrum of presentation and prognosis.
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