MR angiography after coiling of intracranial aneurysms

Introduction Endovascular occlusion with detachable coils has become an alternative treatment to neurosurgical clipping of intracranial aneurysms over the last two decades. Its minimal invasiveness is the most important advantage of this treatment compared to clipping. The disadvantage of occlusion with coils is an approximately 20% risk of reopening of the aneurysm as a result of coil impaction, dissolution of thrombus, or growth of the aneurysm and 10% of coiled patients need additional treatment. As a consequence, patients need to be followed up after coiling to detect and treat reopening and thereby prevent rupture of a reopened aneurysm. The standard technique to follow up coiled patients is intra-arterial digital subtraction angiography (IA-DSA) but this is an invasive and irradiating procedure for which a short hospitalization is required. Magnetic resonance angiography (MRA) could be a good alternative because this imaging technique is non-invasive, non-irradiating, cheaper than IA-DSA, and does not require hospitalization. The aim of this thesis is to evaluate whether the diagnostic performance of MRA in coiled patients is sufficient to replace IA-DSA as the first-choice follow-up modality for these patients. Methods We first calculated test characteristics of MRA with IA-DSA as the reference test, then we evaluated the added value of contrast-enhanced MRA to unenhanced MRA, and finally we assessed the cost-effectiveness of follow-up with MRA compared to follow-up with IA-DSA. Besides, we studied coil-artifact production on MRA for which we varied field strength, scan parameters, and coil materials. We also evaluated whether blood-vessel anatomy influences the risk of aneurysm reopening. Finally, the long-term bleeding risk from adequately coiled aneurysms at 6-months follow-up has been assessed. Results We found good test characteristics of MRA with a high negative predictive value and similar treatment decisions on MRA and IA-DSA. Test characteristics were similar for MRA at 1.5 Tesla and 3.0 Tesla and contrast-enhanced MRA did not have additional value to unenhanced MRA. MRA appeared to be cost-effective compared to IA-DSA. We furthermore found that intra-voxel dephasing, which is influenced by the echo time, is the dominant mechanism in coil-artifact production on unenhanced MRA. At 3.0 Tesla, artifact reduction through the possible echo-time shortening even compensated for artifact enlargement through increased field disturbances at higher field strength. Then, aneurysms at sharper bifurcation angles, thus more flow deviation at the aneurysm base, seem to carry a higher risk for reopening but this finding needs to be confirmed in a larger cohort. And finally, the long-term bleeding risk for patients with an adequately coiled aneurysm at 6-months follow-up is very small. Conclusions Patients with coiled intracranial aneurysms should be followed up by MRA instead of IA-DSA. For MRA, generally no contrast enhancement is required and it can be performed at either 1.5 Tesla or 3.0 Tesla as long as the echo time is as short as possible while keeping acceptable SNR. Thus far, we cannot select patients who are at risk for reopening after coiling so we need to follow up all coiled patients. Future studies could focus on risk profiles of patients for tailored follow-up schedule

Brainstem influences on biceps reflex activity and muscle tone in the anaesthetized rat

This study analyzes the effect of electrical stimulation of the locus coeruleus (LC) and adjacent brainstem structures on the tonic reflex (TVR), the tonic stretch reflex (TSR) and on muscle tone (MT) in anaesthetized rat. Increases in TVR. TSR and MT of the m. biceps were evoked from regions rostrally and ventrally of LC, the caudal pontine reticular nucleus. the cuneiform nucleus and from the ventral paris of the colliculus inferior. Stimulation of the LC did not influence biceps EMG activity. The results indicate that the observed facilitation of muscle activity is due to stimulation of parts of the mesencephalic locomotor region. It is discussed that the recorded increase in TVR. TSR and MT possibly is due to an excitatory action on alpha-motoneurones on one hand and to an enhanced fusimotor drive on the other

Decision analysis to complete diagnostic research by closing the gap between test characteristics and cost-effectiveness

Objective: The lack of a standard methodology in diagnostic research impedes adequate evaluation before implementation of constantly developing diagnostic techniques. We discuss the methodology of diagnostic research and underscore the relevance of decision analysis in the process of evaluation of diagnostic tests. Study Design and Setting: Overview and conceptual discussion. Results: Diagnostic research requires a stepwise approach comprising assessment of test characteristics followed by evaluation of added value, clinical outcome, and cost-effectiveness. These multiple goals are generally incompatible with a randomized design. Decision-analytic models provide an important alternative through integration of the best available evidence. Thus, critical assessment of clinical value and efficient use of resources can be achieved. Conclusion: Decision-analytic models should be considered part of the standard methodology in diagnostic research. They can serve as a valid alternative to diagnostic randomized clinical trials (RCTs). (C) 2009 Elsevier Inc. All fights reserved

[Acute treatment of hypertension in intracerebral haemorrhage]

Item does not contain fulltextThus far no effective treatment for an intracerebral haemorrhage has been available. A randomized clinical trial recently showed that treatment of hypertension in the acute phase of spontaneous intracerebral haemorrhage with a target systolic blood pressure of 140 mmHg is safe and improves prognosis. The effect of blood pressure reducing therapy was small and not statistically significant for the primary outcome (mortality or severe morbidity). Moreover, this effect was shown in one trial only. Therefore the clinical relevance of these study results remains debatable. Considering all available arguments, in patients with a systolic blood pressure >150 mmHg in the first 6 hours after spontaneous intracerebral haemorrhage the Dutch Neurovascular Working Group recommends lowering the blood pressure to a target systolic level of 140 mmHg within 1 hour and maintaining this target level for 1 week. When this strategy is not chosen, we recommend that a systolic blood pressure >180 mmHg should be treated anyway, with a target level of 160 mmHg

[Acute treatment of hypertension in intracerebral haemorrhage]

Item does not contain fulltextThus far no effective treatment for an intracerebral haemorrhage has been available. A randomized clinical trial recently showed that treatment of hypertension in the acute phase of spontaneous intracerebral haemorrhage with a target systolic blood pressure of 140 mmHg is safe and improves prognosis. The effect of blood pressure reducing therapy was small and not statistically significant for the primary outcome (mortality or severe morbidity). Moreover, this effect was shown in one trial only. Therefore the clinical relevance of these study results remains debatable. Considering all available arguments, in patients with a systolic blood pressure >150 mmHg in the first 6 hours after spontaneous intracerebral haemorrhage the Dutch Neurovascular Working Group recommends lowering the blood pressure to a target systolic level of 140 mmHg within 1 hour and maintaining this target level for 1 week. When this strategy is not chosen, we recommend that a systolic blood pressure >180 mmHg should be treated anyway, with a target level of 160 mmHg

Cost-effectiveness of magnetic resonance angiography versus intra-arterial digital subtraction angiography to follow-up patients with coiled intracranial aneurysms

Background and Purpose-To follow up patients with coiled intracranial aneurysms, magnetic resonance angiography (MRA) is a promising noninvasive alternative to current standard intra-arterial digital subtraction angiography (IA-DSA). MRA test results do not always concord with those of IA-DSA, and the impact of discrepancies on health benefits and costs is unknown. We evaluated the cost-effectiveness of follow-up with MRA vs IA-DSA to assess whether in this setting MRA may replace IA-DSA. Methods-We studied aneurysm occlusion on MRA in addition to follow-up IA-DSA in 310 patients with 341 coiled intracranial aneurysms. The observed sensitivity (82%) and specificity (89%) of MRA for detection of reopening with IA-DSA as a reference were used as input for a Markov decision-analytic model. Other determinants were derived from the literature. We compared life expectancy, quality-adjusted life-years (QALY), costs, and expected number of events for the two strategies. Results-Follow-up with MRA yielded similar life expectancy (MRA, 26.66 years; IA-DSA, 26.63 years; difference, 0.03 years; 95% CI, -0.17-0.23) and QALY (MRA, 10.96; IA-DSA, 10.95; difference, 0.01 QALY; 95% CI, -0.05-0.08) at lower costs (MRA, $7003; IA-DSA,$8241 per patient; difference, -$ 1238; 95% CI, -2617- -36). The expected number of events was comparable except for complications from IA-DSA. Conclusion-MRA provided equivalent health benefits as IA-DSA and was cost-saving. MRA dominates and should replace routine IA-DSA to follow-up patients with coiled aneurysms. (Stroke. 2010; 41: 1736-1742.)

Long-term recurrent subarachnoid hemorrhage after adequate coiling versus clipping of ruptured intracranial aneurysms

BACKGROUND AND PURPOSE: Coiling is increasingly used as treatment for intracranial aneurysms. Despite its favorable short-term outcome, concerns exist about long-term reopening and inherent risk of recurrent subarachnoid hemorrhage (SAH). We hypothesized a higher risk for recurrent SAH after adequate coiling compared with clipping. METHODS: Patients with ruptured intracranial aneurysms coiled between 1994 and 2002 with adequate (>90%) aneurysm occlusion at 6-month follow-up angiograms were included. We interviewed these patients about new episodes of SAH. By survival analysis, we assessed the cumulative incidence of recurrent SAH after coiling and compared it with the incidence of recurrent SAH in a cohort of 748 patients with clipped aneurysms by calculating age and sex-adjusted hazard ratios. RESULTS: Of 283 coiled patients with a total follow-up of 1778 patient-years (mean, 6.3 years), one patient had a recurrent SAH (0.4%) and 2 patients had a possible recurrent SAH. For recurrent SAH within the first 8 years after treatment, the cumulative incidence was 0.4% (95% CI, -0.4 to 1.2) after coiling versus 2.6% (95% CI, 1.2 to 4.0) after clipping (hazard ratio, 0.2; 95% CI, 0.03 to 1.6). For possible and confirmed recurrent SAH combined, the cumulative incidence was 0.7% (95% CI, 0.3 to 1.7) after coiling versus 3.0% (95% CI, 1.3 to 4.6) after clipping (hazard ratio, 0.7; 95% CI, 0.2 to 2.3). CONCLUSIONS: Patients with adequately occluded aneurysms by coiling at short-term follow-up are at low risk for recurrent SAH in the long term. Within the first 8 years after treatment, the risk of recurrent SAH is not higher after adequate coiling than after clipping