Cerebral angiographic risk in mild cerebrovascular disease

Cost savings associated with the nonroutine use of carotid angiography

BACKGROUND

To evaluate the economic impact of performing carotid endarterectomy based only on a diagnosis of duplex scanning, we evaluated a cohort of patients treated at our institution during 1 calendar year.

METHODS

Ninety-seven patients were evaluated and divided into two groups: those with and without arteriogram prior to their operation. Duplex scan and arteriogram results were reviewed to determine their effect on the operative plan. Hospital charges and physician fees were assessed for each patient admission. Operative results, complications, and total charges were compared between the two groups.

RESULTS

There was one operative stroke in each group for a stroke rate of 2%. Angiographic complications included one stroke and one femoral artery thrombosis. Two arteriograms led to a change in the operative plan. The hospital charges for patients without an arteriogram was $10,292 verses $13,906 for patients with an arteriogram (P < 0.01). Physician charges for patients without an arteriogram were $3,882, with angiograms and $6,297. The total charges related to the endarterectomy were $14,174 and $20,203, respectively. Arteriograms accounted for an increase of 43% in total charges.

CONCLUSION

Nonroutine use of angiography does not increase operative risk or postoperative length of stay, and preoperative angiography increases total charges by 43% ($6,029) per patient.

Postoperative spiral computed tomography and magnetic resonance angiography after aneurysm clipping with titanium clips

OBJECTIVE

To reduce morbidity and mortality after subarachnoid hemorrhage, it is imperative to evaluate the results of the surgical treatment of cerebral aneurysms. We investigated the usefulness of spiral computed tomography (CT) and magnetic resonance angiography as postoperative control examinations after cerebral aneurysms were clipped with titanium clips.

METHODS

Eleven patients with 13 treated aneurysms were studied prospectively with postoperative digital subtraction angiography, spiral CT, and magnetic resonance angiography. The occlusion of the dome of the aneurysm, the presence of a remnant of the neck, the patency of the parent vessels and other major vessels, and the presence of vasospasm were investigated.

RESULTS

The different parameters could all be well evaluated by postoperative spiral CT. The artifacts caused by the titanium clips, although relatively small compared with artifacts from other clips, precluded evaluating the dome and the neck of the aneurysm with magnetic resonance angiography.

CONCLUSION

In our opinion, spiral CT promises to become a valuable aid in in the postoperative evaluation of clipped aneurysms, and we recommend its routine performance. Postoperative digital subtraction angiography remains the gold standard and has to be performed when spiral CT reveals abnormalities, when the neck of the aneurysm cannot be evaluated because the clip overlays it, or when, intraoperatively, imperfect clipping is suspected and intraoperative angiography cannot be performed.

Emergency imaging of the acute stroke patient

Patients presenting with suspected acute stroke require rapid diagnosis and treatment. Neuroimaging is critical in determining acute-stroke type and thus appropriate management. A review of various neuroimaging techniques and their role in the evaluation of both acute ischemic stroke and acute hemorrhagic stroke is provided.

Does carotid duplex imaging render angiography redundant before carotid endarterectomy?

Carotid duplex imaging is now recognized as the best non-invasive screening test for carotid artery stenosis. The evidence for its use as the sole diagnostic imaging modality prior to carotid endarterectomy is examined. Providing it is carried out by experienced trained operators using validated duplex criteria, carotid duplex imaging is safe, highly sensitive and specific, and superior to angiography at plaque characterization and evaluation of flow disturbance. Cerebral CT or MRI should be performed if symptoms are atypical or if there is an evolved stroke. Angiography is required when duplex imaging is suboptimal or equivocal, in the presence of atypical symptoms or uncommon vascular abnormalities. In the majority of patients requiring endarterectomy for symptomatic high grade ICA stenosis, angiography seldom adds relevant information, and clinical assessment and carotid duplex imaging alone can be safely used in preoperative assessment.

Familial intracranial aneurysms

BACKGROUND

We set out to determine the prevalence of incidental intracranial aneurysms in first-degree relatives aged 30 years or more of people with intracranial aneurysms, and to see if polycystic kidney disease contributes to the aggregation of familial intracranial aneurysms.

METHODS

91 families with two or more affected members had previously been identified from a 14 year series of 1150 intracranial aneurysm patients treated at the University Hospital of Kuopio, Finland. Magnetic resonance angiography was used as a preliminary screening method, followed by conventional four-vessel angiography to verify suspected aneurysms. Participants were also screened for polycystic kidneys by ultrasonography.

FINDINGS

Incidental aneurysms were detected in 40 individuals: 38 of 438 individuals from 85 families without polycystic kidney disease or other diagnosed heritable disorders, and two of 22 individuals from six families known to have polycystic kidney disease. The crude and age-adjusted prevalence of incidental intracranial aneurysms among screened first-degree relatives was 8.7 (SE 1.3)% (95% CI 6.2-11.7) and 9.1 (1.4)% (6.2-11.7), respectively, for the familial group and the crude prevalence for the polycystic kidney group was 9.1 (6.1)% (1.1-29.2).

INTERPRETATION

Our results demonstrate a high prevalence of incidental intracranial aneurysms among first-degree relatives aged 30 years or older of patients with the condition and indicate that the risk of having an aneurysm is about four times higher for a close relative than for someone from the general population. Also, polycystic kidney disease families are a small fraction of the familial intracranial aneurysm families.

Cost-effectiveness of carotid endarterectomy in asymptomatic patients

PURPOSE

The purpose of this study was to determine the cost-effectiveness of carotid endarterectomy for treating asymptomatic patients with > or = 60% internal carotid stenosis, based on outcomes reported in the Asymptomatic Carotid Atherosclerosis Study (ACAS).

METHODS

A cost-effectiveness analysis was performed using a Markov decision model in which the probabilities for base-case analysis (average age, 67 years; 66% male; perioperative stroke plus death rate, 2.3%; ipsilateral stroke rate during medical management, 2.3% per year) were based on ACAS. The model assumed that patients who had TIAs or minor strokes during medical management crossed over to surgical treatment, and used the NASCET data to model the outcome of these now-symptomatic patients. Average cost of surgery ($8500), major stroke ($34,000 plus $18,000 per year), and other costs were based on local cost determinations plus a review of the published literature. Cost-effectiveness was calculated as the incremental cost of surgery per quality-adjusted life year (QALY) saved when compared with medical treatment, discounting at 5% per year. Sensitivity analysis was performed to determine the impact of key variables on cost-effectiveness.

RESULTS

In the base-case analysis, surgical treatment improved quality-adjusted life expectancy from 7.87 to 8.12 QALYs, at an incremental lifetime cost of $2041. This yielded an incremental cost-effectiveness ratio of $8,000 per QALY saved by surgical compared with medical treatment. The high cost of care after major stroke during medical management largely offset the initial cost of endarterectomy in the surgical group. Furthermore, 26% of medically managed patients eventually underwent endarterectomy because of symptom development, which also decreased the cost differential. Sensitivity analysis demonstrated that the relative cost of surgical treatment increased substantially with increasing age, increasing perioperative stroke rate, and decreasing stroke rate during medical management.

CONCLUSION

For the typical asymptomatic patient in ACAS with > or = 60% carotid stenosis, our results indicate that carotid endarterectomy is cost-effective when compared with other commonly accepted health care practices. Surgery does not appear cost-effective in very elderly patients, in settings where the operative stroke risk is high, or in patients with very low stroke risk without surgery.

Pseudo- and segmental occlusion of the internal carotid artery: a new classification, surgical treatment and results

OBJECTIVES

Occluded internal carotid arteries imply a high risk of ischaemic complications, but an "occluded" carotid artery is not always totally occluded. Pseudo- and segmental occlusions can be detected angiographically, and increasingly non-invasively, and include a variety of morphologic findings.

METHODS AND MATERIALS

128 patients with pseudo- or segmental occlusion were treated in a 13 year period. Three different types of pseudo- or segmental occlusion were identified. In most cases a subtotal stenosis (near-occlusion) at the carotid bifurcation is the underlying lesion (type I). In approximately 35% the internal carotid artery is totally occluded at the bifurcation, but collaterals prevent downstream occlusion (type II), or retrograde flow from the circle of Willis and ophthalmic artery preserves a patent petrous part and siphon (type III).

RESULTS

In 79% patency of the arteries could be restored. Three patients (2.3%) died perioperatively, nine (7%) developed ischaemic stroke (7 ipsilateral, 2 contralateral), one intracerebral haemorrhage. The combined stroke-mortality rate was 8.6%. During follow-up (41 +/- 29.9 months) four patients (4.5%) experienced a stroke (3 ipsilateral, 1 contralateral), one an intracranial (1.1%) haemorrhage and six transient ischaemic attacks (6.7%). The annual ipsilateral stroke rate was 0.9%, the cumulative patency rate of the entire series 78% after 73 months.

CONCLUSIONS

Although the surgical management carries an increased risk of complications (stroke, transient ischaemic attacks) compared to conventional carotid endarterectomy it is likely that the stroke risk can be reduced at least for symptomatic patients. Symptomatic internal carotid artery occlusion diagnosed non-invasively should be confirmed angiographically to exclude pseudo- or segmental occlusion.

Accuracy of duplex sonography before carotid endarterectomy--a comparison with angiography

OBJECTIVES

The aim of this prospective study was to contribute to the evaluation of the reliability of Duplex sonography (DS) before carotid endarterectomy (CEA).

DESIGN

The study was performed prospectively in a university hospital setting.

METHODS

Eighty-one consecutive patients aged 49-83 years were examined with DS and carotid angiography (CAG) before CEA. The results of the DS were judged as either confident, or CAG was assessed to be necessary preoperatively. The results from the DS and the CAG were then compared.

RESULTS

DS was judged as confident in 148 of the 162 arteries examined. In none of these 148 arteries did CAG change patient management in any way, and the agreement between DS and CAG was good. In the remaining 14 arteries CAG was judged necessary, in 11 arteries because DS assessed the internal carotid artery (ICA) as occluded, which was confirmed by CAG in 10 arteries. In three arteries the reason was poor quality of the DS, however these three arteries were correctly assessed as severely diseased.

CONCLUSIONS

This study confirms that DS alone is sufficient in the preoperative evaluation before CEA, provided that CAG is performed whenever DS shows occlusion of the ICA, or when the quality of the DS is poor.

Microembolism in Cerebral Angiography

Using transcranial Doppler monitoring of middle cerebral artery blood flow velocity, a number of studies have detected transient high intensity embolic signals during cerebral angiography. These are particularly frequent during contrast injection, but also sometimes occur at the time of catheter and wire manipulations and following saline flushes. These embolic signals appear to be asymptomatic, although a correlation with subtle neurological damage, by neuropsychological evaluation for example, has not been made. Experimental studies in flow models and animal models suggest that the majority of these signals represent air emboli. These are most commonly introduced at the time the contrast is drawn up and at the time of contrast injection. The former can be reduced by allowing the contrast to stand prior to injection. The latter appears to be due to cavitation bubbles and can be reduced by reducing the speed of injection. Using current transcranial Doppler machines, it is impossible to be certain whether some of the embolic signals, particularly at times other than contrast injection, may be due to particulate, rather than air, emboli, but technological improvements may allow this distinction to be made in the future. (ECHOCARDIOGRAPHY, Volume 13, September 1996)

Carotid endarterectomy without angiography

Between 1 January 1990 and 1 September 1994 a total of 109 carotid endarterectomies were performed without preoperative angiography. Only two cases were considered by the surgeon to have a poor correlation between the duplex examination results and intraoperative findings; the outcome was good in both. The perioperative mortality rate was 1.8 per cent, one patient dying from sudden haematoma causing asphyxia and the other from unrelated causes following a myocardial revascularization procedure. Two non-disabling strokes also occurred. These results suggest that carotid endarterectomy based on carotid duplex scanning alone without preoperative angiography is safe in selected patients.

Non-invasive testing for cerebrovascular disease

Selecting the appropriate investigation for diagnosing occlusive cerebrovascular disease depends on the availability, cost, accuracy, invasiveness and the purpose of the test. Intraarterial digital subtraction angiography remains the gold standard, but for accuracy the stenosis should be measured rather than estimated. Duplex ultrasonography is almost as accurate and can additionally analyse plaque morphology. Of 2651 duplex tests carried out in our laboratory, 12.2% were for reversible ischaemic attacks, 2.7% for amaurosis, 12.1% for cervical bruit and 4.3% for vertebrobasilar ischaemia. Duplex within 30 days of operation was carried out on 607 patients (22.9%) and surveillance on 1000 others (37.7%). Asymptomatic carotid stenosis > 60% should be confirmed by intra-arterial digital subtraction angiography, magnetic resonance angiography or spiral computed tomography angiography. For typical transient ischaemic attacks, duplex or angiography alone is adequate but when the clinical presentation is atypical, a confirming test is required. Routine preoperative brain computed tomography is not cost-effective, being equivalent to US$ 4300-11840 per perioperative stroke in our institution. Postoperative surveillance is justified, costing only US$ 505 per patient over 4 years.

Comparison of magnetic resonance angiography and conventional angiography in sickle cell disease: clinical significance and reliability

We retrospectively reviewed the medical records and conventional angiograms of 21 patients with known sickle cell disease, who underwent a total of 50 magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA) studies. MRA and conventional angiography were assessed separately for evidence of stenosis or occlusion. Follow up MRI/MRA studies were also assessed for evidence of progression, regression or stability of the disease in these patients. In the carotid circulation, MRA made the correct diagnosis in 85% of the vessels evaluated with a sensitivity of 80.5% and a specificity of 94%. MRA was also found to show evidence of disease progression, more often than did MRI or the clinical condition of the patients.

Magnetic resonance angiographic assessment after extracranial-intracranial bypass surgery

Extracranial-intracranial (EC-IC) bypass operation may be performed to augment the distal cerebral circulation. The bypass patency is usually assessed postoperatively with conventional cerebral angiography. Six patients are reported in whom the bypass patency was assessed using magnetic resonance angiography (MRA): Two had intracavernous carotid aneurysms, three had base of skull tumours encompassing the internal carotid artery, and one had occlusion of the right internal carotid artery with poor collateral reserve as confirmed by an acetazolamide stimulation test. Postoperative conventional cerebral angiography was also obtained in three patients for comparison. The MRA correlated reasonably well with conventional cerebral angiography in showing bypass patency, although conventional cerebral angiography was superior in demonstrating small vessels; MRA has the added advantage of showing the relative flow contribution and flow direction under physiological conditions by using targeted presaturation pulses.

Incidental intracranial vascular pathology in patients investigated for carotid stenosis

The assessment of cervical and cranial carotid arteries for atherosclerotic disease is the second commonest referral for angiography in our neuroradiological department; in 1993 this accounted for approximately 17% of the total cases. This is due to the resurgence of interest in endarterectomy for severe carotid stenosis. Although the degree of stenosis can usually be assessed adequately by duplex Doppler ultrasonography, angiography is still recommended as a preoperative examination. The intracranial vessels are visualised, which we consider important when planning vascular surgery. We present a prospective study of 100 patients referred for angiographic assessment of carotid stenosis. As well as giving information about the carotid bifurcation, angiography showed 9 patients to have aneurysms, 2 arteriovenous malformations and 15 severe intracranial atherosclerosis. We consider these "incidental" findings important for future management and highlight the need for thorough assessment of the intracranial vessels in these patients by angiography.

Carotid endarterectomy in asymptomatic patients--is contrast angiography necessary? A morbidity analysis

PURPOSE

Findings from the Asymptomatic Carotid Atherosclerosis Study (ACAS) indicate that carotid endarterectomy can be beneficial in symptom-free patients with 60% to 99% carotid artery stenosis. However, patients in ACAS who underwent contrast angiography (CA) before carotid endarterectomy were exposed to an additional 1.2% risk of stroke.

METHODS

We used the methods of decision analysis to assess whether the overall 5-year stroke risk in symptom-free patients with suspected carotid artery disease can be reduced by preoperative imaging with magnetic resonance angiography (MRA) or duplex ultrasonography (DU). We compared four strategies for the preoperative evaluation of carotid artery stenosis in symptom-free patients: 1) CA alone, 2) MRA alone, 3) DU alone, and 4) MRA and DU with CA when the results of these tests disagree. Accuracies of MRA and DU were estimated from 81 patients exposed to all three procedures; stroke risks for patients with 60% to 99% carotid artery stenosis were obtained from ACAS.

RESULTS

For predicting 60% to 99% carotid stenoses, sensitivity and specificity for noninvasive tests, optimized to reduce morbidity, were as follows: DU (0.96, 0.66), MRA (1.00, 0.76), DU/MRA (1.00, 0.86; 26% would require CA). The 5-year stroke risk of these four strategies in order of decreasing benefit was MRA, 6.17%; MRA/DU, 6.34%; DU, 6.35%; and CA, 7.12%. In sensitivity analyses, noninvasive tests were advantageous even if the stroke rate with CA diminished to 0.4%, or if the sensitivity and specificity of noninvasive tests fell to 70%.

CONCLUSION

The preoperative use of noninvasive tests resulted in a lower 5-year stroke risk compared with CA in symptom-free patients with suspected carotid artery stenosis.

Management of transient ischaemic attacks and stroke

The management of stroke and transient ischaemic attacks (TIAs) has changed greatly in the last two decades. The importance of good blood pressure control is the hallmark of stroke prevention. Large multicentre trials have proven beyond doubt the value of aspirin in TIAs, warfarin in patients with atrial fibrillation and embolic cerebrovascular symptoms, and carotid endarterectomy in patients with carotid TIAs. There seems little doubt that patients managed in acute stroke units are more likely to be independent at six months than those managed in a general medical ward. This article emphasizes the importance of basing clinical management on simple history taking and examination and appropriate investigation. This, combined with knowledge of the natural history risk of TIA and stroke and the results of randomised trials, allows individuals to be managed in the most appropriate manner. This review is designed to be a practical guide, useful in the day to day management of patients with cerebrovascular disease.

Imaging blood vessels of the head and neck

ATHEROSCLEROTIC DISEASE: Patients with transient ischaemic attacks or a non-disabling stroke who are surgical candidates should be screened with Doppler ultrasound, or MRA/CT, or both. The choice will depend on local expertise and availability. If DUS is used it is recommended that the equipment is regularly calibrated and a prospective audit of results, particularly of those patients that go on to angiography, is maintained locally. Those patients found to have the DUS equivalent of a 50% stenosis should have angiography only if surgical or balloon angioplasty treatment is contemplated. Angiography should be performed with meticulous technique to minimise risks. ANEURYSM AND ARTERIOVENOUS MALFORMATIONS: Angiography remains the investigation of choice for patients with subarachnoid haemorrhage. Magnetic resonance angiography and CT can demonstrate the larger aneurysm but because even small aneurysms can rupture with devastating effects, these techniques are not the examination of first choice. Angiography is also the only technique that adequately defines the neck of an aneurysm. This information is becoming increasingly important in management decisions-for instance, whether to clip or use a coil. Likewise angiography is the only technique to fully define the vascular anatomy of arteriovenous malformations although the size of the nidus can be monitored by MRA and this is a useful method of follow up after stereotactic radiosurgery, embolisation, or surgery. There are specific uses for MRA such as in patients presenting with a painful 3rd nerve palsy and as a screening test for those patients with a strong family history of aneurysms. VASCULITIS, FIBROMUSCULAR HYPERPLASIA, AND DISSECTION: These rare arterial diseases are best detected by angiography, although there are increasing reports of successful diagnosis by MRA. There are traps for the many unwary and MRA does not give an anatomical depiction of the arteries but a flow map. Slow flow may lead to signal loss and a false positive diagnosis of vasculitis.

Asymptomatic carotid stenosis: how should it be managed?

OBJECTIVE

To discuss the implications of recent studies on carotid endarterectomy for asymptomatic carotid stenosis.

DATA SOURCES

Trials of the effectiveness of carotid endarterectomy in asymptomatic carotid stenosis, including the Asymptomatic Carotid Atherosclerosis Study (ACAS).

RESULTS

In the ACAS study, carotid endarterectomy for asymptomatic moderate to severe carotid stenosis (60%-99% luminal obstruction) reduced the absolute risk of ipsilateral stroke or death at five years by 5.9%. This means that about 17 patients need to be operated on to prevent one stroke or death over five years. To operate on all Australians with asymptomatic 60%-99% carotid stenosis would cost an estimated $A1.24 billion and prevent 800 strokes per year, or only 3% of all first strokes in Australia.

RECOMMENDATIONS

In order to identify who will benefit from carotid endarterectomy and who will remain symptom-free without it, patients should continue to be allocated to the ongoing Asymptomatic Carotid Surgery Trail. Otherwise, carotid endarterectomy should be reserved for patients at high risk of stroke (i.e., with 95%-99% carotid stenosis) who are medically fit for surgery and willing to take the small short term risk of surgery for a possible greater long term benefit.

Screening for asymptomatic internal carotid artery stenosis: duplex criteria for discriminating 60% to 99% stenosis

PURPOSE

The Asymptomatic Carotid Atherosclerosis Study (ACAS) showed that carotid endarterectomy reduces stroke risk in symptom-free patients with 60% or greater internal carotid artery (ICA) stenosis. This will surely lead to the performance of an increased number of screening duplex examinations. Assuming that positive study results will lead to arteriography or endarterectomy and keeping in mind the modest benefit for prophylactic endarterectomy demonstrated by ACAS (absolute risk reduction for ipsilateral stroke of 5.8% at 5 years), duplex criteria for 60% or greater ICA stenosis must have high positive predictive values (PPV). Determining criteria for 60% or greater stenosis, which emphasized high accuracy and PPV, forms the basis for this study.

METHODS

Stenoses detected by angiography in 352 ICAs were blindly compared with those detected by duplex scanning. Duplex criteria were determined for highest overall accuracy in detection of 60% or greater ICA stenosis and for 95% or greater PPV.

RESULTS

Maximal accuracy for detection of 60% or greater stenosis was 90%. This was achieved by the combination of a peak systolic velocity of 260 cm/sec or greater and an end diastolic velocity of 70 cm/sec or greater (sensitivity 84%, specificity 94%, PPV 92%). The 95% PPV for 60% or greater stenosis results from combining peak systolic velocity of 290 cm/sec or greater and end diastolic velocity of 80 cm/sec or greater.

CONCLUSIONS

With use of these criteria duplex scanning accurately detects with high PPVs the threshold level of ICA stenosis defined in ACAS as receiving stroke reduction benefit from prophylactic carotid endarterectomy. These criteria should be useful for carotid artery screening and minimizing unneeded intervention.

Magnetic resonance angiography in moyamoya disease

Spontaneous occlusion of the circle of Willis, i.e., moyamoya disease (MMD), is a clinical disease entity angiographically characterized by progressive and bilateral stenosis of the carotid bifurcation, with a hazy collateral network at the base or convexity of the brain. Although the importance of computed tomography (CT) and conventional magnetic resonance (MR) imaging in diagnosing MMD has already been determined, conventional arteriography is still regarded as necessary for definitive diagnosis. Magnetic resonance angiography (MR-A) is a very recent vascular imaging technique which allows noninvasive and direct imaging of vessels without the use of contrast medium. We present four pediatric cases of MMD, evaluated by conventional angiography, CT, MR imaging, and MR-A. Our data demonstrate that MR-A is successful both in allowing detection of occlusive disease of the basal portion of the internal carotid artery and large branch basal cerebral vessels and demonstrating the collateral vessels at the base of the brain. As a noninvasive procedure, MR-A promises to become a valuable alternative to classical angiography in the diagnosis of MMD.

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.

Spontaneous internal carotid artery dissection: early diagnosis and management in 44 patients

First symptoms and initial clinical, ultrasonographic and neuroradiological findings ascertained a mean of 5.6 days (SD = 5.6 days), 7.7 days (7.0), and 11.2 days (8.0) after symptom onset were analysed in 44 patients who suffered a spontaneous internal carotid artery dissection (ICD) verified by magnetic resonance imaging, angiography, or both. Common symptoms signalling dissection were unilateral headache in 68%, transient ischaemic attack in 20%, and cerebral infarction in 9%. Severe pain preceded cerebral ischaemia by more than 3 days in 60% of those patients who eventually suffered a stroke. However, only 2 were admitted because of pain alone and 33 for evolving neurological deficits. During the first month, ipsilateral severe headache occurred in 89%, neck pain in 36%, ipsilateral cerebral ischaemia in 82%, ocular ischaemia in 16%, oculosympathetic palsy in 48%, and cranial nerve palsy in 5%. Recent "trivial" head or neck trauma was elicited in 41%. Doppler and duplex sonography confirmed the clinical suspicion of ICD in 91.5% and in 96% of those with a significant stenosis or occlusion. MRI demonstrated a thickened vessel wall in all 33 imaged carotid dissections and a mural haematoma in 30. None of the 32 patients who received anticoagulant treatment subsequently deteriorated. Monitoring anticoagulant treatment with ultrasonographic follow-up studies demonstrated recanalization in 70% and persistent occlusion in 30%. The results demonstrate that familiarity with the initial symptoms, especially headache, and performance of an ultrasonographic study without delay are the cornerstones of an early diagnosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Experimental investigation of hypercoagulant conditions associated with angiography

PURPOSE

To evaluate changes in blood coagulability after high-velocity intravascular fluid injections under conditions relevant to angiography.

MATERIALS AND METHODS

In 101 rabbits, fluids were injected at 1,000 psi (6,890 kPa) via a multiple-side-hole catheter in the abdominal aorta, while blood was simultaneously aspirated via a second downstream catheter. The fluids injected included saline, contrast media, blood, tissue plasminogen activator, and heparin. The aspirate was evaluated for clotting time with an activated clotting time (ACT) device, for elevated levels of plasma hemoglobin to confirm capture of at least part of the injection bolus in the sample, and sometimes for hematocrit or fibrin degradation products (FDP).

RESULTS

A single high-pressure injection of 2 mL of saline briefly accelerated the ACT of a blood-saline bolus (mean, 38% +/- 4). The mean volume of the hypercoagulable bolus was 15 mL. Systemic FDP levels became elevated within a few minutes after initial injection, suggesting activation of the fibrinolytic system by intravascular clot formation. Subsequent injections produced less hypercoagulability, probably reflecting the anticoagulant effects of FDP. Pressure-injected contrast agents had anticoagulant effects. The ACT was accelerated by up to 80% after injection of blood that had remained within the catheter for 3-10 minutes. Glove powder or gauze lint from wiping the guide wire markedly accelerated intracatheter clotting. Hypercoagulability after injection of clotting blood was partially prevented by injections with contrast agent and was completely inhibited by low-dose systemic heparinization.

CONCLUSION

A hypercoagulable bolus may occur after angiographically relevant high-pressure fluid injections. The major contributing factors appear to be high jet velocities and injection of small amounts of clotting blood. Heparinization provides a simple and effective means of prevention.

Magnetic resonance angiography in 140 neuropediatric patients

Three-dimensional magnetic resonance angiography (MRA) is a noninvasive technique that images the intracranial arterial vasculature without contrast agents. The suitability of MRA was evaluated for routine use and all children were prospectively studied with conventional MR imaging and time off flight MRA (FISP3D). All MR studies were performed on a 1.5 T-MRA system using a circularly polarized head coil. The study comprised 140 children, ages 3 weeks to 18 years, with different neuropediatric diseases. Major cervical and intracranial arteries were visualized in all age groups. Smaller branches of the supratentorial arteries were identified inconstantly and the number of arteries visualized increased up to the age of 6 years. Sixty-seven children (47%) had normal intracranial vasculature. MRA demonstrated anatomic variations in 21 patients (15%). Twenty-two of 32 children with congenital malformations demonstrated abnormalities of the intracranial vasculature. The diagnostic value of MRA was confirmed in 11 of 12 patients after neonatal stroke and in 3 of 10 children after stroke at older ages. Seven of 18 children with acute hemorrhage demonstrated arteriovenous malformations or an aneurysm on MRA. The correlation with digital subtraction angiographic findings was established in 13 patients. In 9 of 13 children with brain tumor, MRA proved to be diagnostically valuable. MRA proved to be of particular value in the evaluation of the carotid artery following extracorporeal membrane oxygenation therapy. MRA can be used in children of all age groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Non-selective digital subtraction angiography in comparison with selective conventional angiography in the diagnosis of carotid artery disease

In the recent past, non-selective arterial digital subtraction angiography (NSDSA) seemed a less invasive alternative to conventional filmscreen angiography (CFA) in the diagnosis of carotid artery disease. NSDSA obviated the need for selective catheterization with its associated risks but yet took advantage of the DSA method. However, this technique has not found general application although there are no reports that formally assess the (dis)advantages of NSDSA. The aim of our study was to compare the reliability of NSDSA with CFA in evaluation of carotid bifurcations in patients with transient ischemic attacks or partial stroke by reviewing prospectively collected data. Over a 2-year period, 40 patients (upper age limit 65 years) underwent both NSDSA and CFA. Bilateral NSDSA was performed in all 40 patients (80 bifurcations). Bilateral CFA was performed in 27 patients whereas unilateral CFA was carried out in 13 patients (67 bifurcations). Inter- and intra-observer variability for the degree of stenosis was determined by calculation of kappa-values for a 4-point and a 2-point scale. The proportion of interpretable studies was significantly lower in NSDSA. The inter- and intra-observer agreement was on average better in CFA examinations, though the difference was only statistically significant for the inter-observer agreement. The results of our study indicate that images obtained with NSDSA give less reliable information about carotid artery disease than images obtained with CFA. This is in accordance with the fact that NSDSA now seems an abandoned technique.

Carotid endarterectomy without arteriography

Arteriography has been considered the "gold standard" for evaluation of the cerebrovascular circulation prior to carotid endarterectomy. However, arteriography is associated with a neurologic complication rate of up to 12% in certain high-risk groups. Previous studies have shown that the duplex scanner has greater sensitivity than arteriography when both are correlated to the surgical specimen. From January 1986 to December 1991 a total of 174 carotid endarterectomies were performed in 152 patients, of which 61% were symptomatic. A total of 110 carotid endarterectomies in 92 patients were performed without the use of arteriography. Of the 64 patients in whom arteriograms were obtained, 33 were made at consultation and the others for various indications. Operative findings confirmed the duplex scan findings in all cases. A total of 91% of patients had intraoperative completion arteriograms. Of the 55 patients who also had intracranial views taken, two had a 50% siphon stenosis and one patient had a small intracranial aneurysm. None of these findings would have changed our management. The overall neurologic complication rate was one (0.66%) death due to stroke and four (2.6%) patients with transient ischemic attacks. Carotid endarterectomy can be safely performed without preoperative arteriography based on a detailed history and physical examination that includes bilateral upper extremity blood pressures and a duplex scan performed by a validated laboratory.

Carotid endarterectomy after noninvasive evaluation by duplex ultrasonography and magnetic resonance angiography

Recent studies documenting the efficacy of carotid endarterectomy (CEA) in selected patients provide further impetus for developing noninvasive techniques to evaluate carotid occlusive disease. Eliminating the morbidity due to preoperative angiography would further refine the treatment of this condition. Recent improvements and greater experience with magnetic resonance angiography (MRA) of extracranial vessels have increased the accuracy of this technique. We present our experience using MRA in combination with duplex ultrasonography as the primary mode of preoperative evaluation for CEA. Fifty-two patients referred for CEA underwent these two studies. In 47 patients (90%), significant stenosis (> 70%) was unambiguously identified on both ultrasound and MRA. Forty-one of these patients underwent CEA on the basis of these studies alone, without conventional angiography. In all of these cases, significant stenosis was identified at the time of surgery (100%), and CEA was performed without difficulty or complications. In five cases (9.6%), the MRA and ultrasound findings did not concur exactly. In three of these cases, the interpretation of the two studies differed with respect to the severity of stenosis; in the others, one of the studies was indeterminate. These patients underwent conventional angiography before surgery. Our experience suggests that the combined use of MRA and ultrasonography affords an accurate noninvasive evaluation of carotid occlusive disease sufficient for surgical planning in most cases.

Cerebral ischemia: magnetic resonance angiography and transcranial Doppler evaluation

We examined 21 patients with ischemic cerebrovascular disease using magnetic resonance angiography and transcranial Doppler. In 17 patients (81%), the results obtained by the two methods were concordant. In our opinion, the associated use of transcranial Doppler and magnetic resonance angiography provides an accurate diagnostic evaluation of ischemic stroke patients, not only allowing the site of possible steno-occlusive disease of large and medium cerebral vessels to be identified, but also offering the possibility of obtaining dynamic information concerning the direction of blood flow in the presence of compensatory circulations at the level of Willis' circle.

Management and long-term outcome following subarachnoid haemorrhage and intracranial aneurysm surgery in elderly patients: an audit of 199 consecutive cases

To address the question of managing subarachnoid haemorrhage (SAH) in the older patient, the management and outcome of 199 consecutive patients aged > or = 60 years with a confirmed diagnosis of subarachnoid haemorrhage (n = 186) or an unruptured intracranial aneurysm (n = 13) were reviewed. In seven patients, the cause of the SAH was an arterio-venous malformation and these were excluded from further analysis. Angiography was performed in 141 patients with a complication rate of 2.1%. Angiography was not performed in 51 patients and, in this cohort, the in-patient mortality rate was 68.6% and only 27.5% had a favourable outcome at discharge. Operation was not performed in 21 patients with demonstrated aneurysms for a variety of reasons. In this group, the in-patient mortality rate was 47.6% and 38.1% had a favourable outcome at discharge. Eighty-one patients in good neurological grade underwent surgery for a ruptured aneurysm and six patients underwent surgery for a symptomatic unruptured aneurysm. The surgical mortality was 1.1% and a favourable outcome at discharge was achieved in 83.9% of patients. Thirty-three patients were angiographic negative and there was a favourable outcome in 97% of this group. The management mortality in these selected patients admitted to the Department of Clinical Neurosciences was 24.4% and a favourable outcome was recorded in 66.2% of patients. Long-term follow-up (median 40 months, range 3-120 months) was obtained in 97% of discharged patients. The probability of survival at 60 months for patients in good condition at discharge was 0.826 (95% confidence interval 0.722-0.894).(ABSTRACT TRUNCATED AT 250 WORDS)