Evaluation of early dynamic changes of intracranial arterial occlusion is useful for stroke etiology diagnosis

Current knowledge of large vascular occlusion due to intracranial atherosclerosis: focusing on early diagnosis

Intracranial atherosclerosis (ICAS)-related large vascular occlusion (LVO) was an intractable subtype of acute ischemic stroke (AIS), which always needed rescue angioplasty and stenting and complicated the procedure of endovascular recanalization. Diagnosing ICAS-LVO accurately and early was helpful for both clinical treatment and trials. Digital subtraction angiography (DSA) was unable to provide an early and rapid diagnosis of ICAS-LVO based on current studies. A variety of pre-DSA methods had been used to distinguish ICAS-LVO with other subtypes of ischemic stroke, such as medical histories, clinical presentations, computed tomography or angiography (CT/CTA), and magnetic resonance imaging (MRI/MRA). This article briefly reviewed the status quo of the diagnosis and treatment of ICAS-LVO and summarized early diagnostic methods of ICAS-LVO from different aspects.

Distribution of atherosclerotic stenosis determining early neurologic deterioration in acute ischemic stroke

Background and purpose

Early neurologic deterioration (END) during the acute stage of stroke is clinically important because of its association with poor outcomes. The purpose of this study was (1) to investigate variables associated with END, (2) to determine the distribution of atherosclerotic stenosis associated with END, and (3) to clarify the relationship between END and clinical outcomes.

Methods

516 patients with acute ischemic stroke were included. The median follow-up period was 31.7 months. END was defined as a ≥2 point increase in the National Institutes of Health Stroke Scale (NIHSS), ≥1 point increase in level of consciousness or motor item of the NIHSS, or the development of any new neurological deficits during the first 72 hours of hospitalization. A signal loss on 1.5-T magnetic resonance angiography exceeding 50% was considered to be significant for the categorization of stenosis pattern.

Results

The prevalence of END was 19.0%. END was associated with intracranial atherosclerotic stenosis (IAS) together with large artery atherosclerosis (LAA) subtype. In particular, stenosis of basilar artery or posterior cerebral artery was independently associated with END. Lesion growth or hypoperfusion was more accountable for END in patients with IAS, whereas intracerebral hemorrhage or edema/herniation was more frequently observed in END patients without IAS. Patients with END had a higher rate of mortality, but a similar rate of further vascular events compared to patients without END.

Conclusion

Pre-stroke IAS and LAA subtype could determine the development of END during the acute stage of ischemic stroke.

Impact of Target Arterial Residual Stenosis on Outcome After Endovascular Revascularization

BACKGROUND AND PURPOSE

Acute intracranial occlusion can be associated with in situ thrombo-occlusion in relation to preexisting intracranial atherosclerotic disease. We aimed to assess residual stenosis at the site of a target arterial lesion (TAL) to determine whether residual stenosis at the TAL is associated with underlying intracranial atherosclerotic disease.

METHODS

One hundred and sixty-three patients who underwent endovascular therapy for M1 middle cerebral artery occlusion and achieved angiographic reperfusion were selected for analysis. The presence of residual stenosis at the TAL was classified using the Arterial Occlusive Lesion (AOL) scale at postprocedural angiography, and the severity of stenosis was grouped into none, mild (<50%), moderate (50%-69%), severe (70%-99%), and occlusion on postprocedural and follow-up angiography. We also recorded the incidence of instant reocclusion occurring during the procedure and delayed reocclusion detected on follow-up angiography.

RESULTS

Seventy-four patients (45.5%) showed target arterial residual stenosis (AOL 2). As to the TAL pathogenesis, 40 patients were classified into in situ thrombo-occlusion (54.1% of AOL 2 and 24.5% of M1 occlusion). The occurrence of instant or delayed reocclusion was independently associated with a low chance of favorable 3-month outcome. Furthermore, the occurrence of delayed reocclusion was associated with excellent pretreatment collateral flow and early neurological worsening, but not the severity of residual stenosis at the TAL.

CONCLUSIONS

In population with a high prevalence of intracranial atherosclerotic disease, residual stenosis may be attributed to in situ thrombo-occlusion with underlying intracranial atherosclerotic disease in ≈25% of cases, hindering functional recovery via the occurrence of instant or delayed reocclusion.

Impact of Intracranial Atherosclerotic Stenosis on the Prognosis in Acute Ischemic Stroke Patients with Cardioembolic Source

BACKGROUND AND AIM

In recent days, intracranial atherosclerotic stenosis (IAS) has been reportedly related to recurrent stroke and mortality in the total patient population with ischemic stroke. However, its impact on the prognosis of the patients with cardioembolic source is not yet established. This study attempted to investigate whether IAS was associated with poor outcome in stroke patients with cardioembolic source.

METHODS

Overall, 223 patients with acute ischemic stroke and cardioembolic source were included in this study. IAS was defined as ≥ 50% stenosis on enhanced MRA, and cardioembolic sources were detected by ECG and echocardiography. Follow-up data were obtained from outpatient medical records and/or telephone interviews.

RESULTS

Overall, 60 major clinical events causing poor outcome occurred in 58 patients (26.0%). Patients with IAS had significantly higher rates of death and stroke recurrence than those without IAS (p = 0.015 and 0.046 each by log rank test). The multivariate Cox proportional hazards regression analysis showed that IAS was significantly related to the poor outcome (hazard ratio 1.725, 95% confidence interval 1.020-2.920, p = 0.042).

CONCLUSIONS

In acute ischemic stroke patients with cardioembolic source, IAS may be considered a marker of a high risk of stroke recurrence or death.

Magnetic resonance imaging in acute ischemic stroke treatment

Although intravenous administration of tissue plasminogen activator is the only proven treatment after acute ischemic stroke, there is always a concern of hemorrhagic risk after thrombolysis. Therefore, selection of patients with potential benefits in overcoming potential harms of thrombolysis is of great importance. Despite the practical issues in using magnetic resonance imaging (MRI) for acute stroke treatment, multimodal MRI can provide useful information for accurate diagnosis of stroke, evaluation of the risks and benefits of thrombolysis, and prediction of outcomes. For example, the high sensitivity and specificity of diffusion-weighted image (DWI) can help distinguish acute ischemic stroke from stroke-mimics. Additionally, the lesion mismatch between perfusion-weighted image (PWI) and DWI is thought to represent potential salvageable tissue by reperfusion therapy. However, the optimal threshold to discriminate between benign oligemic areas and the penumbra is still debatable. Signal changes of fluid-attenuated inversion recovery image within DWI lesions may be a surrogate marker for ischemic lesion age and might indicate risks of hemorrhage after thrombolysis. Clot sign on gradient echo image may reflect the nature of clot, and their location, length and morphology may provide predictive information on recanalization by reperfusion therapy. However, previous clinical trials which solely or mainly relied on perfusion-diffusion mismatch for patient selection, failed to show benefits of MRI-based thrombolysis. Therefore, understanding the clinical implication of various useful MRI findings and comprehensively incorporating those variables into therapeutic decision-making may be a more reasonable approach for expanding the indication of acute stroke thrombolysis.

Intracranial atherosclerosis

Atherosclerotic disease often involves the intracranial arteries including those encased by cranial bones and dura, and those located in the subarachnoid space. Age, hypertension, and diabetes mellitus are independent risk factors for intracranial atherosclerosis. Intracranial atherosclerosis can result in thromboembolism with or without hypoperfusion leading to transient or permanent cerebral ischaemic events. High rates of recurrent ischaemic stroke and other cardiovascular events mandate early diagnosis and treatment. Present treatment is based on a combination of antiplatelet drugs, optimisation of blood pressure and LDL cholesterol values, and intracranial angioplasty or stent placement, or both, in selected patients.

Effect of statin on progression of symptomatic intracranial atherosclerosis

BACKGROUND

Symptomatic intracranial atherosclerosis (ICAS) is a dynamic disease that frequently progresses. Statins have been shown to have anti-atherosclerotic activity. We therefore investigated whether statins could prevent progression of ICAS.

METHODS

This retrospective cohort study assessed 55 patients with acute ischemic stroke and symptomatic ICAS in the middle cerebral or basilar arteries as shown on magnetic resonance angiography (MRA), with follow-up MRA performed more than 1 year after the index stroke. Change in ICAS was classified as progressive, regressive, or stable. Baseline clinical characteristics and risk factor control during follow-up were assessed, and laboratory tests were performed at the time of follow-up MRA. The statin group was defined as patients regularly treated with statins for more than 75% of the follow-up period; the remaining patients were defined as the non-statin group.

RESULTS

At a median follow-up time of 21.8 months (range, 11.8-66.1 months), the statin group consisted of 26 (47.3%) patients and the non-statin group of 29 (52.7%). During follow-up, 6 (10.9%) patients progressed, 14 (25.5%) regressed, and 35 (63.6%) remained stable. Statin treatment was significantly associated with non-progression of ICAS (p=0.024). Two patients in the non-statin group had recurrent strokes. Border-zone infarcts were associated with progression of ICAS (3/6, 50%; p=0.007), whereas risk factors and inflammatory biomarkers were not related to progression.

CONCLUSIONS

Treatment with statins may prevent progression of symptomatic ICAS. Prospective randomized controlled trials are required to confirm that statins protect against such progression.

Estimation of stroke etiology from lesion patterns on diffusion-weighted magnetic resonance imaging in patients with carotid artery occlusive disease

BACKGROUND

Various mechanisms can be considered in ischemic stroke with internal carotid artery (ICA) occlusive diseases. We clarified the etiologic mechanisms from lesion patterns on diffusion-weighted imaging (DWI).

METHODS

One hundred and twenty consecutive ischemic stroke patients with ipsilateral ICA occlusive diseases were enrolled and classified into 3 groups according to the size of DWI lesions: group A, massive; group B, moderate-to-large; and group C, small. Group C was divided into 3 subgroups according to the number of lesions: C1, 1-3; C2, 4-9; and C3, 10 or more. The relationship between the DWI findings and stroke subtypes according to the TOAST classification was investigated.

RESULTS

Cardioembolism was significantly more common in groups A and B than in group C, while large-artery atherosclerosis (LAA) was more frequent in group C than in groups A and B. In group A, cardioembolism accounted for 32%, while LAA was not observed. Statistical analyses showed trends toward a higher frequency of LAA in groups C2 and C3 than in group C1.

CONCLUSIONS

Mechanisms of acute stroke in ICA diseases can be simply assessed from the lesion size and number, which may be useful in considering acute therapeutic strategies.