High‐resolution diffusion‐weighted imaging identifies ischemic lesions in a majority of transient ischemic attack patients

A systematic review of the incidence and outcomes of ICD-11 defined stroke

BACKGROUND

The World Health Organisation has expanded the definition of stroke to include people with symptoms less than 24 h if they have evidence of stroke on neuroimaging. The impact is that people previously diagnosed as having a transient ischaemic attack (TIA) would now be considered to have had a stroke. This change will impact incidence and outcomes of stroke and increase eligibility for secondary prevention. We aimed to evaluate the new ICD-11 criteria retrospectively to previous TIA studies to understand the change in incidence and outcomes of this type of stroke.

METHODS

We conducted a systematic review of observational studies of the incidence and outcomes of clinically defined TIA. We searched PubMed, EMBASE, and Google Scholar from inception to 23rd May 2023. Study quality was assessed using a risk of bias tool for prevalence studies.

FINDINGS

Our review included 25 studies. The rate of scan positivity for stroke among those with clinically defined TIA was 24 %, (95 % CI, 16-33 %) but with high heterogeneity (I2 = 100 %, p <0.001). Sensitivity analyses provided evidence that heterogeneity could be explained by methodology and recruitment method. The scan positive rate when examining only studies at low risk of bias was substantially lower, at 13 % (95 % CI, 11-15 %, I2 = 0, p = 0.77). We estimate from population-based incidence studies that ICD-11 would result in an increase stroke incidence between 4.8 and 10.5 per 100,000 persons/year. Of those with DWI-MRI evidence of stroke, 6 % (95 % CI, 3-11 %) developed a recurrent stroke in the subsequent 90 days, but with substantial heterogeneity (I2 = 67 %, p = 0.02).

CONCLUSION

The impact of the ICD-11 change in stroke definition on incidence and outcomes may have been overestimated by individual studies. Community-based stroke services with access to DWI MRI are likely to accurately diagnose greater numbers of people with mild ICD-11 stroke, increasing access to effective prevention.

Thirty-six months recurrence after acute ischemic stroke among patients with comorbid type 2 diabetes: A nested case-control study

Background

Stroke patients have to face a high risk of recurrence, especially for those with comorbid T2DM, which usually lead to much more serious neurologic damage and an increased likelihood of death. This study aimed to explore determinants of stroke relapse among patients with comorbid T2DM.

Materials and methods

We conducted this case-control study nested a prospective cohort of ischemic stroke (IS) with comorbid T2DM. During 36-month follow-up, the second stroke occurred in 84 diabetic IS patients who were allocated into the case group, while 613 patients without recurrence were the controls. We collected the demographic data, behaviors and habits, therapies, and family history at baseline, and measured the variables during follow-up. LASSO and Logistic regression analyses were carried out to develop a prediction model of stroke recurrence. The receiver operator characteristic (ROC) curve was employed to evaluate the performance of the prediction model.

Results

Compared to participants without recurrence, the higher levels of pulse rate (78.29 ± 12.79 vs. 74.88 ± 10.93) and hypertension (72.6 vs. 61.2%) were recorded at baseline. Moreover, a lower level of physical activity (77.4 vs. 90.4%), as well as a higher proportion of hypoglycemic therapy (36.9 vs. 23.3%) was also observed during 36-month follow-up. Multivariate logistic regression revealed that higher pulse rate at admission (OR = 1.027, 95 %CI = 1.005–1.049), lacking physical activity (OR = 2.838, 95% CI = 1.418–5.620) and not receiving hypoglycemic therapy (OR = 1.697, 95% CI = 1.013–2.843) during follow-up increased the risk of stroke recurrence. We developed a prediction model using baseline pulse rate, hypoglycemic therapy, and physical activity, which produced an area under ROC curve (AUC) of 0.689.

Conclusion

Physical activity and hypoglycemic therapy play a protective role for IS patients with comorbid diabetes. In addition to targeted therapeutics, the improvement of daily-life habit contributes to slowing the progress of the IS.

Cerebral microbleeds following thoracic endovascular aortic repair

BACKGROUND

Stroke and neurological injury are a complication of thoracic endovascular aortic repair (TEVAR). Cerebral microbleeds (CMBs) are common in patients with white matter damage to the brain secondary to chronic vasculopathy. The aim of this study was to examine the occurrence of CMBs after TEVAR, and to evaluate their association with patient and procedural factors.

METHODS

Patients who underwent TEVAR between September 2018 and January 2020 in two specialist European aortic centres were analysed. All patients underwent postoperative susceptibility-weighted MRI. The location and number of CMBs were identified, and analysed with regard to procedural aspects, clinical outcome, and Fazekas score as an indicator of pre-existing vascular leucoencephalopathy.

RESULTS

Some 91 patients were included in the study. A total of 1531 CMBs were detected in 58 of 91 patients (64 per cent). In the majority of affected patients, CMBs were found bilaterally (79 per cent). Unilateral CMBs in the right or left hemisphere occurred in 16 and 5 per cent of patients respectively (P < 0.001). More CMBs were found in the middle cerebral than in the vertebrobasilar/posterior and anterior cerebral artery territories (mean(s.d.) 3.35(5.56) versus 2.26(4.05) versus 0.97(2.87); P = 0.045). Multivariable analysis showed an increased probability of CMBs after placement of TEVAR stent-grafts with a proximal diameter of at least 40 mm (odds ratio (OR) 6.85, 95 per cent c.i. 1.65 to 41.59; P = 0.007) and in patients with a higher Fazekas score on postoperative T2-weighted MRI (OR 2.62, 1.06 to 7.92; P = 0.037).

CONCLUSION

CMBs on postoperative MRI are common after endovascular repair in the aortic arch. Their occurrence appears to be associated with key aspects of the procedure and pre-existing vascular leucoencephalopathy.

Estimation of the Morphofunctional Status of the Brain in Hypertensive Wistar Rats Using Diffusion-Weighted MRI

Morphofunctional changes of the brain tissues of Wistar rats were studied based on the development of a multifactor cardiovasorenal model of arterial hypertension using MRI. An increase of the signal on the diffusion brain maps was recorded in 3 months, which indicated fluid accumulation in the intra- and extracellular space of the brain tissue. The data characterize the development of the pathogenetic mechanism of the hypervolemic variant of experimental arterial hypertension. The development of endothelial dysfunction in the brain vessels was manifested by predominance of abnormal constrictor reactions. In 6 months after arterial hypertension simulation, structural changes in the brain developed, such as leukoareosis, cystic encephalomalacia with dilated cerebrospinal fluid spaces and limited blood supply to brain tissue in the basins of the large cerebral arteries.

European Stroke Organisation (ESO) guidelines on management of transient ischaemic attack

The aim of the present European Stroke Organisation Transient Ischaemic Attack (TIA) management guideline document is to provide clinically useful evidence-based recommendations on approaches to triage, investigation and secondary prevention, particularly in the acute phase following TIA. The guidelines were prepared following the Standard Operational Procedure for a European Stroke Organisation guideline document and according to GRADE methodology. As a basic principle, we defined TIA clinically and pragmatically for generalisability as transient neurological symptoms, likely to be due to focal cerebral or ocular ischaemia, which last less than 24 hours. High risk TIA was defined based on clinical features in patients seen early after their event or having other features suggesting a high early risk of stroke (e.g. ABCD2 score of 4 or greater, or weakness or speech disturbance for greater than five minutes, or recurrent events, or significant ipsilateral large artery disease e.g. carotid stenosis, intracranial stenosis). Overall, we strongly recommend using dual antiplatelet treatment with clopidogrel and aspirin short term, in high-risk non-cardioembolic TIA patients, with an ABCD2 score of 4 or greater, as defined in randomised controlled trials (RCTs). We further recommend specialist review within 24 hours after the onset of TIA symptoms. We suggest review in a specialist TIA clinic rather than conventional outpatients, if managed in an outpatient setting. We make a recommendation to use either MRA or CTA in TIA patients for additional confirmation of large artery stenosis of 50% or greater, in order to guide further management, such as clarifying degree of carotid stenosis detected with carotid duplex ultrasound. We make a recommendation against using prediction tools (eg ABCD2 score) alone to identify high risk patients or to make triage and treatment decisions in suspected TIA patients as due to limited sensitivity of the scores, those with score value of 3 or less may include significant numbers of individual patients at risk of recurrent stroke, who require early assessment and treatment. These recommendations aim to emphasise the importance of prompt acute assessment and relevant secondary prevention. There are no data from randomised controlled trials on prediction tool use and optimal imaging strategies in suspected TIA.

Spectral analysis of EEG in etiological assessment of patients with transient neurological deficits

OBJECTIVE

Differentiating transient ischemic attack from stroke mimics may be difficult. Besides clinical evaluation and brain imaging, electroencephalography (EEG) may be a useful diagnostic tool.

METHODS

We conducted spectral analysis on 67 EEG of patients who had presented a transient neurological deficit (TND) within the previous seven days. Expert clinicians provided the final diagnosis: transient ischemic attack, migraine with aura, focal seizure or "other". We first calculated the relative power of the four EEG frequency bands (delta, theta, alpha and beta), in the whole hemisphere, then, according to the clinical symptoms, in the relevant electrodes of the symptomatic hemisphere. Finally, we calculated the relative power ratio between symptomatic and asymptomatic hemispheres.

RESULTS

Median age was 60.6 years (57% females). The etiological diagnosis was transient ischemic attack (27%), migraine with aura (11%), focal seizures (22%) and "other" (40%). We did not find significant differences in the theta and delta relative power analysis between groups. Over the symptomatic hemisphere only, we found a significant increase of the alpha relative power (p = 0.0026, p < 0.0001, p = 0.0014) in the migraine group compared to transient ischemic attack, migraine and focal seizures groups, and a significant decrease of the beta relative power (p = 0.0034, p = 0.0016, p = 0.0005) compared to the same groups.

CONCLUSIONS

Migraine with aura presents a discriminative EEG relative power in comparison to transient neurological deficits of other origins. To further investigate the additive diagnosis value of EEG in other TND, future studies should be performed with an EEG obtained within the first 24 h after the onset of symptoms.

SIGNIFICANCE

Spectral EEG analysis discriminates migraine with aura groups from other groups, but not at the individual level.

Chinese medicine Tongxinluo capsule protects against blood-brain barrier disruption after ischemic stroke by inhibiting the low-density lipoprotein receptor-related protein 1 pathway in mice

BACKGROUND

Chinese medicine Tongxinluo capsule (TXL) has been extensively used to treat ischemic stroke in China, and one of its mechanisms is to protect against blood brain barrier (BBB) disruption after stroke. However, the underlying protective mechanisms are not fully illuminated. It is reported that the low-density lipoprotein receptor-related protein 1 (LRP-1) is involved in BBB disruption after brain ischemia. In this study, we explored whether TXL could downregulate LRP-1 expression and subsequently protect against BBB disruption after stroke using permanent middle cerebral artery occlusion (pMCAO) in mice.

METHODS

The animal model of ischemic stroke was induced by pMCAO in male adult C57BL/6J mice. The mice were orally administered TXL (3.0 g/kg) at 1, 3 and 21 h after pMCAO. Meanwhile, the LRP-1 antagonist receptor associated protein (RAP) was intracerebroventricularly injected at 1 and 21 h after stroke. We measured the following parameters at 6 and 24 h: LRP-1 protein level, BBB leakage, and the expression of tight junction (TJ) proteins including occludin, claudin-5 and zonula occludens-1 (ZO-1).

RESULTS

Our results showed that TXL downregulated LRP-1 level, upregulated these TJ proteins level, and reduced BBB leakage in peri-infarct regions after pMCAO. Further study found that the inhibitor RAP played the same role as did TXL in upregulating these TJ proteins level and reducing BBB leakage after stroke.

CONCLUSION

Our study demonstrates that TXL protects against BBB disruption after stroke via inhibiting the LRP-1 pathway.

Spatial Resolution and the Magnitude of Infarct Volume Measurement Error in DWI in Acute Ischemic Stroke

BACKGROUND AND PURPOSE

Infarct volume in acute ischemic stroke is an important prognostic marker and determines endovascular treatment decisions. This study evaluates the magnitude and potential clinical impact of the error related to partial volume effects in infarct volume measurement on diffusion-weighted MR imaging in acute stroke and explores how increasing spatial resolution could reduce this error.

MATERIALS AND METHODS

Diffusion-weighted imaging of 393 patients with acute stroke, of whom 56 had anterior circulation large-vessel occlusion, was coregistered to standard space. Lesion boundaries were manually segmented. A 3D lesion-volume model was resampled for voxel sizes from 4 × 4 × 8 to 1 × 1 × 2 mm, and the surface-volume, corresponding to the partial volume error, was calculated. The number of cases with anterior circulation large-vessel occlusion, in which the endovascular therapy core threshold of 70 mL was contained within the margin of error, was calculated as a function of imaging resolution.

RESULTS

The mean infarct core volume was 27.2 ± 49.9 mL. The mean surface volume was 14.7 ± 20.8 mL for 2 × 2 × 4 mm resolution and 7.4 ± 10.7 mL for 1 × 1 × 2 mm resolution. With a resolution of 2 × 2 × 4 mm, 70 mL was contained within the margin of error in 7/56 cases (12.5%) with large-vessel occlusion, while with a 1 × 1 × 2 mm voxel size, the margin of error was 3/56 (5%). The lesion-volume range of potentially misclassified lesions dropped from 46.5-94.1 mL for a 2 × 2 × 4 mm resolution to 64.4-80.1 mL for a 1 × 1 × 2 mm resolution.

CONCLUSIONS

Partial volume effect is an important source of error in infarct volume measurement in acute stroke. Increasing spatial resolution substantially decreases the mean error. Standard use of high-resolution DWI should be considered to increase the reliability of infarct volume measurements.

Dysphasia is associated with diffusion-weighted MRI abnormalities in patients with transient neurological symptoms

Background

The clinical characteristics of diffusion-weighted imaging (DWI) abnormalities after transient neurological symptoms are of great significance for the early diagnosis and urgent intervention of transient ischemic attack (TIA). This study was aimed to investigate the clinical characteristics associated with acute DWI lesions in transient neurological symptoms.

Methods

We retrospectively recruited 302 patients with transient neurological symptoms. According to DWI findings, they were divided into DWI positive and DWI negative group. The clinical characteristics and the TIA-related scores such as ABCD2, ABCD3, ABCD3I, Dawson score, and the Diagnosis of TIA (DOT) score were compared between the two groups. Logistic regression analysis and receiver operating characteristic curves were used to identify the independent factors and compare the predictive value of different TIA scores for acute DWI lesions.

Results

A total of 302 patients were enrolled in this study. The mean age was 61.8 years, and 67.2% were male. We found 89 (29.5%) patients with DWI positivity. Logistic regression analysis showed the characteristic associated with DWI lesions was dysphasia (OR 2.226, 95% CI 1.220–4.062). The area under the curve for Dawson score and the DOT score was 0.610 (95% CI 0.543–0.678) and 0.625 (95% CI 0.559–0.691), respectively.

Conclusion

We found that DWI lesions were detected in 29.5% of patients with transient neurological symptoms and were associated with dysphasia. Dawson score and DOT score could have a higher predictability of DWI lesions in patients with transient neurological symptoms.

Sub-angiographic peripheral emboli in high resolution DWI after endovascular recanalization

Background and aim

To analyze the incidence of peripheral emboli after successful mechanical thrombectomy (MT) of intracranial large vessel occlusions (LVO).

Methods

We performed a prospective analysis of patients with intracranial LVO who underwent successful MT and received a 1.5 T MRI including diffusion-weighted imaging (DWI) in standard- and high-resolution as well as susceptibility-weighted imaging (SWI) on the day following the intervention. Reperfusion grade was assessed on post-thrombectomy digital subtraction angiography (DSA) using the expanded thrombolysis in cerebral infarction (eTICI) scale. Punctuate DWI lesions distal to the DWI core lesion were classified as peripheral emboli. DWI lesions outside the primary affected vascular territory were classified as emboli into new territories. Additionally, SWI and post-thrombectomy DSA were analyzed and correlated to findings on DWI.

Results

Twenty-eight patients undergoing successful MT met the inclusion criteria. In 26/28 patients (93%), a total of 324 embolic lesions were detected in DWI representing 2.1% of the cumulated ischemic core volume. 151 peripheral emboli were detected in standard-resolution DWI, 173 additional emboli were uncovered in high-resolution DWI. Eight out of nine patients with an eTICI 3 reperfusion had embolic lesions (29 DWI lesions). 9.6% (31/324) of peripheral emboli were observed in vascular territories not affected by the LVO. SWI lesions were observed in close proximity to 10.2% (33/324) of DWI lesions.

Conclusions

Peripheral emboli are frequent after MT even after complete reperfusion. These emboli occur rather in the vascular territory of the occluded vessel than in other territories. A large proportion of peripheral emboli is only detected by high-resolution DWI.

Electronic supplementary material

The online version of this article (10.1007/s00415-020-09719-1) contains supplementary material, which is available to authorized users.

Risk factors of perfusion and diffusion abnormalities on MRI in hemispheric TIA: a case-control study

Background

To assess the prevalence and potential predictors of MR diffusion and perfusion abnormalities in a Chinese population with hemispheric transient ischemic attacks (TIA).

Methods

Patients with temporary (<24 hours) focal cerebral dysfunction of probable vascular origin were considered to be potential candidates for this study in the emergency room. Those who were admitted to the stroke center of Shanghai Fourth People's Hospital affiliated to Tongji University between January 2015 and December 2018 were recruited to the present study. MRI, including both diffusion-weighted imaging (DWI) and perfusion-weighted imaging (PWI), was performed within 7 days after the last symptom attack. Time to maximum of the residue function (Tmax) maps were auto-evaluated using the RAPID software to determine hypoperfusion. Multivariate analysis was used to assess the correlation of MR findings with clinical variables, medical history, cardio-metabolic characteristics, and the ABCD2 scores (age, blood pressure, clinical features, symptom duration and diabetes).

Results

Sixty-six out of 207 patients met the inclusion criteria. Baseline MRI showed DWI lesions in 20 patients (30.3%). The prevalence of MR perfusion Tmax >4 s >0 mL and ≥10 mL were 77.3% (51/66) and 50% (33/66), respectively. Male patients tended to develop DWI lesions after a TIA. Limb weakness was an independent factor associated with MR perfusion abnormalities (Tmax >4 s ≥10 mL) in this Chinese population (adjusted OR =7.41, 95% CI: 1.57-34.89, P=0.011).

Conclusions

Our results suggest that limb weakness is a strong predictor of perfusion abnormalities calculated by RAPID on Tmax maps of hemispheric TIA patients without DWI positive findings. Male patients are more likely to develop cerebral infarction.