Stroke: magnitude of the problem and impact on health care.
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Adult↗
Biomedical subjects
M R Mayberg
Publications and source records attributed to M R Mayberg.
Traumatic leptomeningeal cyst in an adult: a case report and review of the literature.
BACKGROUND: Traumatic leptomeningeal cyst as a complication of skull fractures was initially thought to occur primarily in the pediatric population. The occurrence of a traumatic leptomeningeal cyst in the adult population is rare. CASE DESCRIPTION: A lump in the right parietal region of this 53-year-old man prompted a computed tomography (CT) scan. The patient denied any symptoms and was in good health. Examination confirmed a firm, nontender, nonpulsatile mass in the right parietal region of the skull. The CT scan demonstrated a 4 x 3 cm area of irregular bone destruction involving both the inner and outer table of the skull. At operation a distinctly raised paper-thin outer table was noted, and underneath was a soft, tan-colored mass, which measured approximately 2 x 2 cm and was connected to the underlying brain through a 1 cm dural defect. The extradural portion of the mass was amputated, the dura repaired with a pericranium patch, the skull defect was repaired with a split thickness bone graft, and the final pathology was congruent with gliotic brain. CONCLUSION: Although rare, this case demonstrates a traumatic leptomeningeal cyst in an adult.
Adult↗
Balloon angioplasty for the treatment of vasospasm: results of first 50 cases.
OBJECTIVE: To report the results of the first 50 consecutive patients with vasospasm secondary to subarachnoid hemorrhage treated with balloon angioplasty after failure of medical management. METHODS: Retrospective uncontrolled study of 50 consecutive patients treated with balloon angioplasty between February 1988 and July 1992. Forty-six had objective clinical deterioration despite maximal medical therapy, whereas four were treated on the basis of rapidly accelerating transcranial Doppler velocities and decreased regional blood perfusion detected by technetium-99m-exametazime brain single photon emission computed tomography. All patients had evidence of marked vasospasm demonstrated by angiography. Thirty-two (64%) and 46 (92%) patients underwent angioplasty within 12 and 18 hours, respectively. RESULTS: Of the patients with clinical evidence of vasospasm-induced ischemia, 28 (61%) showed sustained neurological improvement within 72 hours of angioplasty. Three (6%) patients deteriorated within 72 hours after angioplasty, with two (4%) patients dying immediately after angioplasty as a result of vessel rupture and the other patient's Glasgow Coma Scale score decreasing by 2. Two additional patients in poor condition with Hunt and Hess Grade V at the time of angioplasty subsequently died during hospitalization. Two other patients died as a result of unclipped aneurysms that subsequently bled 4 and 12 days after angioplasty, respectively. The improvement demonstrated clinically, angiographically, and by transcranial Doppler after angioplasty was sustained, with only one patient requiring subsequent angioplasty of a previously dilated segment (total, 170 vessel segments dilated). Two patients developed vasospasm in previously undilated segments. CONCLUSION: Timely balloon angioplasty can reverse delayed ischemic deficit caused by vasospasm in patients for whom medical therapy has failed.
Angioplasty, Balloon↗
Comparison of balloon angioplasty and papaverine infusion for the treatment of vasospasm following aneurysmal subarachnoid hemorrhage.
OBJECT: The purpose of this study was to test the hypothesis that balloon angioplasty is superior to papaverine infusion for the treatment of proximal anterior circulation arterial vasospasm following subarachnoid hemorrhage (SAH). Between 1989 and 1995, 125 vasospastic distal internal carotid artery or proximal middle cerebral artery vessel segments were treated in 52 patients. METHODS: Blood flow velocities of the involved vessels were assessed by using transcranial Doppler (TCD) monitoring in relation to the day of treatment with balloon angioplasty or papaverine infusion. Balloon angioplasty and papaverine infusion cohorts were compared based on mean pre- and posttreatment velocity at 24 and 48 hours using the one-tailed, paired-samples t-test. Balloon angioplasty alone was performed in 101 vessel segments (81%) in 39 patients (75%), whereas papaverine infusion alone was used in 24 vessel segments (19%) in 13 patients (25%). Although repeated treatment after balloon angioplasty was needed in only one vessel segment, repeated treatment following papaverine infusion was required in 10 vessel segments (42%) in six patients because of recurrent vasospasm (p < 0.001). Seven vessel segments (29%) with recurrent spasm following papaverine infusion were treated with balloon angioplasty. Although vessel segments treated with papaverine demonstrated a 20% mean decrease in blood flow velocity (p < 0.009) on posttreatment Day 1, velocities were not significantly lower than pretreatment levels by posttreatment Day 2 (p = 0.133). Balloon angioplasty resulted in a 45% mean decrease in velocity to a normal level following treatment (p < 0.001), a decrease that was sustained. CONCLUSIONS: Balloon angioplasty is superior to papaverine infusion for the permanent treatment of proximal anterior circulation vasospasm following aneurysmal SAH.
Adult↗
Cerebral vasospasm.
Established vasospasm is refractory to vasodilators, although certain agents (nimodipine or papavarine) may reverse early vasospasm when administered in high local concentrations. Calcium channel antagonists do not affect the incidence of arteriographic vasospasm and probably improve outcome by other mechanisms. Mechanical dilatation of cerebral arteries in chronic vasospasm (angioplasty) produces a long-lasting increase in arterial caliber. Prolonged exposure of cerebral arteries to perivascular blood (probably OxyHb) is necessary for the development of vasospasm. Experimental data have implicated lipid peroxidation or inflammatory responses in the pathogenesis of vasospasm. OxyHb is the most likely pathogenic agent for vasospasm, although the specific mechanism is uncertain. OxyHb causes vasoconstriction by agonist-mediated SMC contraction and catalyzes the formation of reactive oxygen species with subsequent lipid peroxidation. Morphologic changes in SMC have been consistently observed in human and experimental vasospasm. Chronic exposure to perivascular blood produces reduced vessel wall compliance and insensitivity to vasoconstrictors and vasodilators. Although endothelial damage after SAH is sufficient to stimulate only minimal SMC proliferation, the physiologic response of injured endothelium may be manifested by increased ET-1 secretion, augmented platelet adherence, and increased permeability.
Animals↗
Progressive aneurysmal degeneration of cortical venous drainage of dural arteriovenous malformations: case report.
OBJECTIVE AND IMPORTANCE: The development of a venous aneurysm associated with dural arteriovenous malformations rarely has been documented in the literature. CLINICAL PRESENTATION: A 64-year-old man with known dural arteriovenous malformations developed a venous aneurysms, as shown on sequential angiograms obtained during 2 years. INTERVENTION: The dural arteriovenous malformations were treated with neuroendovascular embolization and then surgical excision. CONCLUSION: The clinical presentation, diagnosis, and treatment of this unusual case are presented.
Angiography, Digital Subtraction↗
Analysis of outcome in carotid endarterectomy trials.
The trials for carotid endarterectomy have had a major impact on the practice of medicine. Beyond demonstrating the efficacy of this procedure for stroke prevention in certain patient cohorts, these studies have set a standard for the evaluation of surgical procedures by carefully planned, scientifically rigorous, prospective randomized controlled trials. In addition, data from these trials have been used to develop clinical guidelines (2, 12, 24), determine reimbursement policies, and establish criteria for perioperative morbidity. Concordance of methodology (especially primary outcome measures) among the various trials has enabled important valid comparisons between different patient cohorts. The benefit provided by carotid endarterectomy in most trials was so profound that the relative imprecision of stroke-related outcome measures did not significantly affect the findings. New outcome measures for stroke that evolved during these studies are being applied to ongoing trials for a variety of stroke therapies.
Carotid Stenosis↗
Management of internal carotid artery occlusion.
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Carotid Artery, Internal↗
Gamma radiation effect on vascular smooth muscle cells in culture.
PURPOSE: Prior work in our laboratory demonstrated that external gamma irradiation administered within 48 h following balloon catheter carotid artery injury in rats produced a marked inhibition of intimal hyperplasia and restenosis. The current study used smooth muscle cells (SMC) in vitro to examine the radiation dose response and to investigate the cellular mechanism by which radiation inhibits SMC proliferation. METHODS AND MATERIALS: Quiescent rat aortic SMC in plasma were refed with whole blood serum to stimulate synchronous proliferation and immediately irradiated with single fraction doses of 1.25-20 Gy. RESULTS: Comparison between a micronucleus assay and a clonogenic assay indicated a dose-dependent inhibition of SMC growth, with an ED50 at 2-3 Gy. The micronucleus assay also demonstrated a dose-dependent increase in apparent chromosomal damage at 72 h after irradiation. Inhibition of SMC growth by radiation did not correlate with changes in intracellular or released mitogenic activity. Furthermore, there was no evidence of apoptosis in irradiated SMC up to 96 h after treatment. CONCLUSION: Radiation likely inhibits SMC proliferation after arterial injury by a dose-dependent mechanism of lethal and/or sublethal cellular injury leading to clonogenic cell death.
Animals↗
The potential role of external beam radiation in preventing restenosis after coronary angioplasty.
The potential role of radiation in the prevention of coronary artery restenosis after angioplasty has generated much recent interest. Animal research and pilot clinical efforts have focused primarily on intraluminal methods of radiation delivery. This article reviews the experience to date with external beam radiation in restenosis prevention and suggests issues that should be considered from the standpoint of both external beam and intravascular radiotherapy. External beam radiation can certainly play an effective role in clinical studies of coronary artery restenosis, and a multicenter randomized trial of external beam radiation after coronary angioplasty has been initiated.
Angioplasty, Balloon, Coronary↗
Reduction of intracellular glutathione levels produces sustained arterial narrowing.
OBJECTIVE: Although lipid peroxidation and alterations in endogenous antioxidants have been hypothesized to contribute to cerebral vasospasm after subarachnoid hemorrhage, there has been no direct evidence demonstrating the relationship between oxidative stress and delayed arterial narrowing. To elaborate the role of the endogenous intracellular antioxidant and electron exchanger glutathione (GSH) in cerebral vasospasm, rat femoral arteries were treated with perivascular application of I-buthionine-(SR)-sulfoximine (BSO), which inhibits the synthesis of GSH. METHODS: To determine the dose-response relationship, BSO at doses of 10 to 100 mg/ml, in platelet-rich plasma, was applied for 7 days to rat femoral arteries in vivo. Vessels were then perfusion-fixed for morphometric analysis of luminal cross-sectional area. To determine the time course of arterial narrowing, BSO (75 mg/ml) was applied to femoral arteries for 1, 3, 7, or 21 days before histological analysis, as described above. With rats treated with 50 to 100 mg/ml BSO, exogenous GSH (100 mg/kg) was administered, by intraperitoneal injection, daily for 7 days. To demonstrate the mechanism of BSO effects in smooth muscle cells (SMCs), cultured rat aortic SMCs were treated with 1 mmol/l BSO for 24 hours and assayed for intracellular levels of GSH and two products of lipid peroxidation, malondialdehyde and 4-hydroxyalkenal. RESULTS: Compared with control arteries treated with platelet-rich plasma alone, perivascularly administered BSO applied for periods of 1 to 21 days produced sustained and reversible narrowing of rat femoral arteries with a time course, severity, and histological appearance analogous to those observed after perivascular application of whole blood. BSO-induced arterial narrowing was dose-dependent, with 60% reductions in the luminal cross-sectional area being noted at 75 and 100 mg/ml (P < 0.005). Systemic administration of exogenous GSH slightly inhibited the effect of BSO on arterial narrowing, although the inhibition was not statistically significant. Cultured rat aortic SMCs exposed to BSO for 24 hours showed a 70% decrease in intracellular GSH levels (P = 0.03); levels of two products of lipid peroxidation, malondialdehyde and 4-hydroxyalkenal, were increased by 25% (P = 0.24) and 38% (P = 0.09), respectively. CONCLUSION: These data support the hypothesis that diminished intracellular levels of GSH may produce delayed chronic arterial narrowing after subarachnoid hemorrhage. The specific mechanism by which GSH levels modulate vasoconstriction remains uncertain but may involve endogenous antioxidant capacity in SMCs.
Animals↗
Effects of irradiation geometry on treatment plan optimization with linac-based radiosurgery.
A comparison was made of different treatment plans to determine the effect on the three-dimensional dose distributions of varying the allowed parameters in linac-based stereotactic radiosurgery with circular collimators; these parameters are arc position, length, and weighting, and collimator diameter. For the class of eccentrically shaped target volumes that are not so irregular as to require several separate isocenters, it was found that superior dose distributions could be achieved by varying arc length, arc position, arc weighting, and collimator diameter. An analysis of the results achieved with an automated planning program indicates that, in general, the variables of arc position and arc length are of greater importance than collimator size or beam weighting. However, there are cases where varying these latter two parameters does result in markedly better dose distributions. A deeper investigation into the effects of multiple collimators on the dose distribution in the area of steepest gradient demonstrated that multiple collimator sizes do not significantly degrade the dose falloff, which is in fact mostly determined by the effects of intersecting arcs.
Brain Neoplasms↗
Transcranial Doppler in the evaluation of internal carotid artery dissection.
BACKGROUND AND PURPOSE: A subject with dissection of the internal carotid artery (ICA) may present with a variety of symptoms, from headache to stroke. Thus far, it has not been possible to identify the subset of patients at risk for cerebral ischemia. Because the majority of these ischemic events are secondary to embolic phenomena, we used transcranial Doppler (TCD) evaluation with emboli monitoring to study 17 consecutive patients with ICA dissection treated at Harborview Medical Center, Seattle, Wash, during a 2-year period from 1992 until 1994. METHODS: Ten patients with ICA dissection secondary to trauma and seven with spontaneous ICA dissection were diagnosed by carotid angiography and studied by TCD from the time of diagnosis through initiation of therapy. Emboli monitoring was performed in the middle cerebral artery (MCA) ipsilateral to the dissection at the initial evaluation and intermittently thereafter to ensure that the emboli stopped with treatment. RESULTS: Emboli were detected in the MCA distal to the dissection in 10 of 17 patients (59%). Patients with microemboli detected by TCD presented with a stroke (70%) much more frequently than those without emboli (14%) (P=.0498). The presence of a pseudoaneurysm did not increase the risk of either microemboli or stroke. CONCLUSIONS: We have demonstrated a high incidence of intracranial microemboli in the MCA distal to carotid dissections and a significant correlation between the presence of emboli and stroke. TCD can therefore be used as an adjunctive tool to manage patients with suspected carotid dissection and may prove useful in evaluating the efficacy of treatment in reducing microemboli and subsequent stroke.
Adolescent↗
A technique for interactive image-guided neurosurgical intervention in primary brain tumors.
Interactive image-guided neurosurgical techniques allow safer and more complete cytoreduction of gliomas. This is most significant for low-grade tumors, whose configurations and margins are perhaps better appreciated by reference to registered MR images rather than by reliance on direct visualization using microscopic illumination. Spatially registered electro-physiologic recordings of intraoperative cortical stimulation to map language and motor function can increase the margin of safety for performing radical resections. By individualizing approaches and optimizing results, these technologies promise a new degree of standardization of outcome after resective surgery for all glial tumors.
Brain Mapping↗
Endarterectomy for asymptomatic carotid artery stenosis. Resolving the controversy.
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Carotid Stenosis↗
Persistent feeding arteries to angiographically completely embolized arteriovenous malformation demonstrated by intraoperative color-flow Doppler testing: report of two cases.
Two cases of arteriovenous malformation (AVM) treated preoperatively by endovascular embolization that appeared to be completely occluded after embolization are presented. Seven and 12 days later, respectively, these patients underwent resection of their AVM. At the time of surgery, intraoperative color-flow Doppler studies revealed persistent feeding arteries to an active residual nidus of the AVM. The significance of this finding is presented in light of previous published literature.
Adult↗
Duplex accuracy compared with angiography in the Veterans Affairs Cooperative Studies Trial for Symptomatic Carotid Stenosis.
Duplex ultrasonography is frequently used for noninvasive screening for extracranial occlusive disease. In a multicenter, prospective, randomized trial for carotid endarterectomy in symptomatic patients, the duplex ultrasound examination was compared with conventional angiographic findings for internal carotid artery (ICA) stenosis in 178 patients. Angiograms were interpreted by radiologists both at local medical centers and at a central site; the angiographic determination of ICA stenosis was calculated as percent diameter at the point of maximal narrowing compared with the normal distal ICA. Comparisons were made for 328 arteries, including both the symptomatic (> 50% stenosis determined by angiography) and the asymptomatic (variable degrees of stenosis) sides. Duplex ultrasonography sensitivity varied from 0.24 for 30 to 49% stenosis to 0.71 for 50 to 79% stenosis and 0.91 for ICA occlusion. Using a 50% stenosis cutpoint, duplex ultrasonography sensitivity was 0.90 with a specificity of 0.76. Duplex scan readings underestimated the degree of stenosis in the 30 to 49% stenosis group in 48% of the cases. There was no apparent relationship between the accuracy of stenosis determinations and that of external carotid artery stenosis, carotid plaque morphology, or ulceration determinations by ultrasound. On the basis of the benefit provided by carotid endarterectomy in symptomatic patients with high-grade lesions, duplex ultrasound accuracy is essential if noninvasive testing is used to make clinical decisions. In situations in which duplex findings may not be reliable, such as in the mild-to-moderate stenosis and occlusion categories, carotid angiography may be indicated.
Angiography↗
Antioxidant and iron-chelating agents in cerebral vasospasm.
Prior work in our laboratory showed that the perivascular application of deferoxamine (an antioxidant and iron-chelating agent) inhibited delayed arterial narrowing after chronic blood exposure in a rat femoral artery model of vasospasm. To determine which of these mechanisms was operant in vasospasm, we compared deferoxamine with two agents (ascorbic acid and U74389F) that have antioxidant but not iron-chelating capacity. For the systemic application of drugs in 23 rats, whole blood encased in a silastic cuff was applied to the right femoral artery of each rat; whole-blood serum (lacking erythrocytes) was similarly applied to the left femoral artery. Deferoxamine (30 mg/kg/d), ascorbic acid (1000 mg/kg/d), U74389F (30 mg/kg/d), or pH-matched control vehicle was administered three times daily by intraperitoneal injection for 7 days. After exposure to whole blood, arteries treated with intraperitoneal vehicle showed an 85% reduction in the lumen, compared with vessels exposed to erythrocyte-free serum (P < 0.001). Intraperitoneal ascorbic acid and U74389F produced moderate amelioration in arterial narrowing (53 and 61% decrease, respectively, in the lumen versus controls; P < 0.05 versus vehicle); deferoxamine had no significant effect when administered intraperitoneally. To test the efficacy of these agents by the perivascular application of drugs, whole blood was applied to both femoral arteries in each of 25 rats. Solutions of deferoxamine (10 mg/ml), ascorbic acid (50 or 100 mg/ml), or U74389F (15 or 30 mg/ml) were directly applied to the perivascular thrombus surrounding the femoral arteries, compared with vehicle applied to contralateral vessels. The perivascular application of 50 mg of ascorbic acid (36% reduction, P < 0.05), 100 mg of ascorbic acid (31% reduction, P < 0.01), or 10 mg of deferoxamine (41% reduction, P < 0.05) significantly inhibited arterial narrowing, compared with vehicle. The application of U74389F at a dose of 15 or 30 mg directly into the perivascular thrombus produced nonsignificant reduction in arterial narrowing. These data suggest that mechanisms other than direct iron toxicity, such as generation of cytotoxic free radicals, may play an important role in cerebral vasospasm. In addition, the route of administration and concentration of drugs in the perivascular region adjacent to the thrombus may be critical to their efficacy.
Animals↗