FLAIR vascular hyperintensity may predict stroke after TIA

Individualized interpretation for the clinical significance of fluid-attenuated inversion recovery vessel hyperintensity in ischemic stroke and transient ischemic attack: A systematic narrative review

Fluid-attenuated inversion recovery (FLAIR) vessel hyperintensity（FVH）refers to the hyperintensity corresponding to the arteries in the subarachnoid space. It is caused by critically slowed blood flow and is commonly encountered in patients with large artery steno-occlusions. Quite a few studies have focused on the clinical significance of FLAIR vessel hyperintensity in terms of its relationship to the prognosis of transient ischemic attack (TIA), baseline severity or infarction volume, early neurological deterioration or infarction growth, and functional outcomes in acute ischemic stroke (AIS). However, inconsistent or conflicting findings were common in these studies and caused confusion in the clinical decision-making process guided by this imaging marker. Through reviewing the available studies on the etiologic mechanism of FVH and investigating findings on its clinical significance in AIS and TIA, this review aims to elucidate the key factors for interpreting the clinical significance of FVH individually.

Hyperintense vessels on imaging account for neurological function independent of lesion volume in acute ischemic stroke

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Studies have revealed variable significance of FLAIR hyperintense vessels (FHV).

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We found number and location of FHV are associated with functional deficits.

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Functional measures correlated with FHV independently of lesion volume.

In acute ischemic stroke, reported relationships between lesion metrics and behavior have largely focused on lesion volume and location. However, hypoperfusion has been shown to correlate with deficits in the acute stage. Hypoperfusion is typically identified using perfusion imaging in clinical settings, which requires contrast. Unfortunately, contrast is contraindicated for some individuals. An alternative method has been proposed to identify hypoperfusion using hyperintense vessels on fluid-attenuated inversion recovery (FLAIR) imaging. This study aimed to validate the clinical importance of considering hypoperfusion when accounting for behavior in acute stroke and demonstrate the clinical utility of scoring the presence of hyperintense vessels to quantify it.

One hundred and fifty-three participants with acute ischemic stroke completed a battery of commonly-used neurological and behavioral measures. Clinical MRIs were used to determine lesion volume and to score the presence of hyperintense vessels seen on FLAIR images to estimate severity of hypoperfusion in six different vascular regions. National Institutes of Health Stroke Scale (NIHSS) scores, naming accuracy (left hemisphere strokes), and language content produced during picture description were examined in relation to lesion volume, hypoperfusion, and demographic variables using correlational analyses and multivariable linear regression.

Results showed that lesion volume and hypoperfusion, in addition to demographic variables, were independently associated with performance on NIHSS, naming, and content production. Specifically, hypoperfusion in the frontal lobe independently correlated with NIHSS scores, while hypoperfusion in parietal areas independently correlated with naming accuracy and content production.

These results correspond to previous reports associating hypoperfusion with function, confirming that hypoperfusion is an important consideration—beyond lesion volume—when accounting for behavior in acute ischemic stroke. Quantifying hypoperfusion using FLAIR hyperintense vessels can be an essential clinical tool when other methods of identifying hypoperfusion are unavailable or time prohibitive.

Negative-FLAIR vascular hyperintensities serve as a marker of no recanalization during hospitalization in acute stroke

BACKGROUND

Since acute fluid-attenuated inversion recovery vascular hyperintensity (FVH) is indicative of disordered blood flow, FVH is considered a marker of acute major arterial occlusion. Conversely, the role of the absence of FVH (negative-FVH) remains unknown.

METHODS

Consecutive stroke patients were studied via magnetic resonance angiography, within 24 h of onset and major arterial occlusion. All patients were examined using serial angiography to evaluate the presence of recanalization. Patients were classified into negative-FVH and positive-FVH groups.

RESULTS

A total of 72 patients (49 [68%] male patients, aged 76 [66-83] years) were enrolled. Ten patients were allocated to the negative-FVH group and 62 to the positive-FVH group. Initial National Institutes of Health Stroke Scale (NIHSS) score was 4 (2-8) in the negative-FVH group and 10 (4-21) in the positive-FVH group (p = 0.012). Recanalization was achieved in 1 (10%) of the 10 patients in the negative-FVH group and in 49 (79%) of the 62 patients in the positive-FVH group during hospitalization (p < 0.001). Patients with recanalization were older (p = 0.023), had higher NIHSS score (p = 0.008), were admitted earlier (p = 0.014), exhibited a higher prevalence of atrial fibrillation (p = 0.010) and anterior circulation occlusion (p = 0.021), and were more frequently treated with hyperacute recanalization therapy (p = 0.004). Multivariate regression analysis demonstrated that negative-FVH (odds ratio 0.087, 95% confidential interval [0.008-0.988], p = 0.049) was a negative independent factor associated with recanalization during hospitalization.

CONCLUSIONS

In conclusion, negative-FVH in acute stroke was associated with lack of recanalization during hospitalization.

Fluid-attenuated inversion recovery vascular hyperintensities in anterior circulation acute ischemic stroke: associations with cortical brain infarct volume and 90-day prognosis

BACKGROUND AND PURPOSE

Fluid-attenuated inversion recovery vascular hyperintensity (FVH) is often observed in conjunction with acute ischemic stroke (AIS) of the carotid system. However, the significance of FVH in patients with AIS has not been fully elucidated. The purpose of this study is to investigate the effects of FVH on the final infarct volume (including cortical and deep brain infarct volume) and on 90-day prognosis in AIS patients.

MATERIAL AND METHODS

We analyzed data of 160 patients who had AIS of anterior circulation. FVH was identified and the cortical brain infarct volume (CBIV) and deep brain infarct volume (DBIV) were calculated. We assessed 90-day clinical outcome using the modified Rankin Scale (mRS).

RESULTS

FVH was identified in 83 of the 160 patients (51.88%). Patients with FVH showed larger CBIV (13.94 ± 25.55 vs. 6.56 ± 13.49 ml; p = 0.025), more frequent intracranial-large artery disease (74.70 vs. 27.27%; p < 0.001), and more severe clinical impairment on admission (NIHSS 7.22 ± 4.01 vs. 5.42 ± 4.52; p = 0.009). Considering the factors influencing prognosis, FVH positivity (OR = 2.12, 95% CI 1.13-3.99; p = 0.02) and NIHSS (at discharge) (OR = 2.14, 95% CI 1.64-2.78; p < 0.001) were independently associated with 90-day clinical outcome of AIS patients.

CONCLUSION

FVH is a more common finding associated with larger CBIV, intracranial-large artery disease, and more severe strokes on admission. In the presence of good collateral circulation, FVH may be a predictor of better outcome in anterior circulation AIS patients at 90 days.

Cerebral Infarction following Acute Subdural Hematoma in Infants and Young Children: Predictors and Significance of FLAIR Vessel Hyperintensity

A phenomenon of cerebral infarction following acute subdural hematoma (ASDH) in infants and young children, termed cerebral infarction following ASDH (CIASDH), has been well recognized, though both its mechanisms and risk factors have been poorly understood. The purpose of the present study was to investigate the predictors for CIASDH in a population of ASDH, and to evaluate the imaging studies to presume the mechanisms of CIASDH. We retrospectively examined consecutive children 6 years of age or younger, who were diagnosed with ASDH and were admitted to our hospital between 2000 and 2014. In 57 consecutive children with ASDH, 12 (21.1%) developed CIASDH. The multivariate analysis revealed five predictors for CIASDH: presence of seizure, consciousness disturbance at admission, absence of skull fracture, hematoma thickness ≥ 5 mm on computed tomography (CT), and midline shift ≥ 3 mm on CT (p < 0.05). In three of six patients (50%) undergoing magnetic resonance (MR) imaging/fluid-attenuated inversion recovery (FLAIR) within 5 days of admission, serpentine hyperintensities in the subarachnoid space (FLAIR vessel hyperintensities) were demonstrated. MR angiography showed neither occlusion nor stenosis of the cerebral arteries. Single photon emission CT performed at admission in one patient showed a cerebral blood flow reduction in the ASDH side. All the children with CIASDH showed unfavorable outcomes at discharge. Children showing multiple predictors at admission should be carefully observed for development of CIASDH. Evaluation of the imaging studies suggested that a blood flow disturbance in the level of peripheral arteries to microcirculation was one candidate for possible mechanisms to induce the CIASDH.

Clinical significance of fluid-attenuated inversion recovery vascular hyperintensities in transient ischemic attack

BACKGROUND AND PURPOSE

Fluid-attenuated inversion recovery vascular hyperintensity (FVH) is often identified in patients with acute ischemic stroke. The purpose of this study was to determine the clinical significance of FVH in patients with transient ischemic attack (TIA).

METHODS

Consecutive inpatients with TIA who underwent MRI within 24 hours of symptom onset were studied. The frequency, relative factors, and time course of FVH were determined.

RESULTS

Of the 202 patients who were enrolled (76 women, mean age, 69.0 ± 13.2 years), FVH was identified in 41 patients (20%). Multivariate analysis showed that atrial fibrillation (odds ratio, 7.14; 95% confidence interval [CI], 2.69-18.1), arterial occlusive lesion (odds ratio, 4.89; 95% CI, 3.03-12.2), and hemiparesis (odds ratio, 2.81; 95% CI, 1.17-7.48) was independently associated with FVH. Of 23 recurrence-free patients with FVH positive undergoing follow-up MRI at a median of 7 days after the onset, FVH was no longer positive in 15 patients (65%). Atrial fibrillation was more common (P=0.027) and arterial occlusive lesion was less common (P<0.001) in patients with transient FVH compared with those with persistent FVH. Within 90 days after the onset, 13 patients developed recurrent TIA or ischemic stroke. After Cox proportional hazard analysis, FVH (hazard ratio, 3.65; 95% CI, 1.09-12.7), arterial occlusive lesion (hazard ratio, 4.15; 95% CI, 1.18-17.1), and coexistence of FVH and arterial occlusive lesion (hazard ratio, 13.9; 95% CI, 3.36-71.0) were significantly associated with recurrent TIA or ischemic stroke.

CONCLUSIONS

The presence of FVH early after symptom onset may help to diagnosis TIA, to identify the potential mechanisms of TIA and to predict recurrence risk after a TIA.

FLAIR vascular hyperintensity preceding stroke in cryptococcal meningitis

BACKGROUND AND PURPOSE

Ischemic stroke is a common complication of cryptococcal meningitis. Fluid attenuated inversion recovery vascular hyperintensity (FVH) is a neuroimaging marker of sluggish blood flow usually seen in the setting of acute stroke. FVH have never been described in the setting of meningitis.

METHODS

Case report.

RESULTS

A 20-year-old man with cryptococcal meningitis and a magnetic resonance imaging demonstrating FVH had subsequent neurological deterioration and was found to have bilateral ischemic stroke.

CONCLUSIONS

In conditions with high risk of stroke, such as meningitis, the presence of FVH should alert the clinician to the possibility of impending infarction.

Fluid-attenuated inversion recovery vascular hyperintensities: an important imaging marker for cerebrovascular disease

Vascular hyperintensities have been noted on FLAIR sequences obtained in the setting of acute stroke and intracranial steno-occlusive disease. The presence of FVHs likely represents disordered blood flow, often from collaterals distal to arterial occlusion or stenosis. As opposed to other vessel signs seen in arterial insufficiency, FVH is unique in that it does not represent thrombus, but rather sluggish or disordered blood flow through vessels. This review will discuss the diagnostic and prognostic value of FVH and its impact on clinical decision-making.

Angiography reveals that fluid-attenuated inversion recovery vascular hyperintensities are due to slow flow, not thrombus

BACKGROUND AND PURPOSE

Fluid-attenuated inversion recovery (FLAIR) vascular hyperintensities (FVH) are commonly encountered on MR imaging studies performed shortly after the onset of acute ischemic stroke. Prior reports have speculated regarding the pathogenesis of this finding, yet definitive correlative angiographic studies have not been performed. We studied the pathophysiologic and hemodynamic correlates of FVH on conventional angiography and concurrent MR imaging sequences.

MATERIALS AND METHODS

Retrospective review of FLAIR and gradient-refocused echo MR imaging sequences acquired immediately before conventional angiography for acute stroke was conducted in a blinded fashion. The presence, location, and morphology of FVH were noted and correlated with markers of thrombotic occlusion and collateral flow on angiography. Angiographic collaterals were graded on a 5-point scale incorporating extent and hemodynamic aspects.

RESULTS

A prospective ischemic stroke registry of 632 patients was searched to identify 74 patients (mean age, 63.4 +/- 20 years; 48% women) having undergone FLAIR sequences immediately before angiography. Median time from FLAIR to angiography was 2.9 hours (interquartile range, 1.1-4.7 hours). FVH were present in 53/74 (72%) of all acute stroke cases with subsequent angiography. FVH distal to an arterial occlusion were associated with a high grade of leptomeningeal collateral blood flow.

CONCLUSIONS

FVH are observed in areas of blood flow proximal and distal to stenosis or occlusion and are noted with more extensive collateral circulation.

The risk of stroke within a week of minor stroke or transient ischemic attack

BACKGROUND

The risk of stroke is highest in the first week following an index stroke or transient ischemic attack (TIA). Recent evidence indicates that prompt pharmacological treatment and evaluation may help mitigate this risk.

OBJECTIVE

To identify risk factors for recurrent stroke 1 week after index cerebrovascular event and review evidence for early and aggressive evaluation and management.

METHODS

We searched the National Library of Medicine Pubmed database to identify studies reporting recurrent or secondary stroke in individuals with identified stroke or TIA.

RESULTS/CONCLUSION

The risk of recurrent stroke in the week after a TIA or minor stroke is up to 10%. Factors identified with risk of early stroke recurrence include age, elevated blood pressure, clinical symptoms of motor weakness or speech disturbance, and large vessel atherothrombotic mechanism. Studies have shown that timely initiation of stroke preventative therapy may reduce the risk of stroke within this early period.