Stroke Mimics in the Acute Setting: Role of Multimodal CT Protocol

BACKGROUND AND PURPOSE

Ischemic stroke can be mimicked by nonischemic conditions. Due to emphasis on the rapid treatment of acute ischemic stroke, it is crucial to identify these conditions to avoid unnecessary therapies and potential complications. We investigated the performance of the multimodal CT protocol (unenhanced brain CT, CTA, and CTP) to discriminate stroke mimics from acute ischemic stroke.

MATERIALS AND METHODS

We retrospectively selected multimodal CT studies performed for clinical suspicion of acute ischemic stroke in our center in a 24-month period, including patients with at least 1 follow-up imaging study (brain CT or MR imaging). Hemorrhagic strokes were excluded. We measured the performance of multimodal CT, comparing the original diagnostic results with the final clinical diagnosis at discharge.

RESULTS

Among 401 patients, a stroke mimic condition was diagnosed in 89 (22%), including seizures (34.8%), migraine with aura attack (12.4%), conversion disorder (12.4%), infection (7.9%), brain tumor (7.9%), acute metabolic condition (6.7%), peripheral vertigo (5.6%), syncope (5.6%), transient global amnesia (3.4%), subdural hematoma (1.1%), cervical epidural hematoma (1.1%), and dural AVF (1.1%). Multimodal CT sensitivity, specificity, and accuracy were 24.7%, 99.7%, and 83%. Multimodal CT revealed peri-ictal changes in 13/31 seizures and diagnosed 7/7 brain tumors, 1/1 dural AVF, and 1/1 subdural hematoma. CT perfusion played a pivotal diagnostic role.

CONCLUSIONS

Multimodal CT demonstrated low sensitivity but high specificity in the diagnosis of stroke mimics in the acute setting. The high specificity of multimodal CT allows ruling out stroke and thereby avoiding unnecessary revascularization treatment in patients with diagnosis of a stroke mimic.

Extracellular Vesicle Surface Markers as a Diagnostic Tool in Transient Ischemic Attacks

BACKGROUND AND PURPOSE

Extracellular vesicles (EVs) are promising biomarkers for cerebral ischemic diseases, but not systematically tested in patients with transient ischemic attacks (TIAs). We aimed at (1) investigating the profile of EV-surface antigens in patients with symptoms suspicious for TIA; (2) developing and validating a predictive model for TIA diagnosis based on a specific EV-surface antigen profile.

METHODS

We analyzed 40 subjects with symptoms suspicious for TIA and 20 healthy controls from a training cohort. An independent cohort of 28 subjects served as external validation. Patients were stratified according to likelihood of having a real ischemic event using the Precise Diagnostic Score, defined as: unlikely (score 0-1), possible-probable (score 2-3), or very likely (score 4-8). Serum vesicles were quantified by nanoparticle tracking analysis and EV-surface antigen profile characterized by multiplex flow cytometry.

RESULTS

EV concentration increased in patients with very likely or possible-probable TIA (P<0.05) compared with controls. Nanoparticle concentration was directly correlated with the Precise Diagnostic score (R=0.712; P<0.001). After EV immuno-capturing, CD8, CD2, CD62P, melanoma-associated chondroitin sulfate proteoglycan, CD42a, CD44, CD326, CD142, CD31, and CD14 were identified as discriminants between groups. Receiver operating characteristic curve analysis confirmed a reliable diagnostic performance for each of these markers taken individually and for a compound marker derived from their linear combinations (area under the curve, 0.851). Finally, a random forest model combining the expression levels of selected markers achieved an accuracy of 96% and 78.9% for discriminating patients with a very likely TIA, in the training and external validation cohort, respectively.

CONCLUSIONS

The EV-surface antigen profile appears to be different in patients with transient symptoms adjudicated to be very likely caused by brain ischemia compared with patients whose symptoms were less likely to due to brain ischemia. We propose an algorithm based on an EV-surface-antigen specific signature that might aid in the recognition of TIA.

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.

History of Hypertension Is Associated With MR Hypoperfusion in Chinese Inpatients With DWI-Negative TIA

Objectives: The present study aimed to examine the prevalence of and risk factors for magnetic resonance (MR) perfusion abnormality in a Chinese population with transient ischemic attack (TIA) and normal diffusion-weighted imaging (DWI) findings.

Methods: Patients with TIA admitted to our stroke center between January 2015 and October 2017 were recruited to the present study. MRI, including both DWI and perfusion-weighted imaging (PWI), was performed within 7 days of symptom onset. Time to maximum of the residue function (T_max) maps were evaluated using the RAPID software (Ischemaview USA, Version 4.9) to determine hypoperfusion. Multivariate analysis was used to assess perfusion findings, clinical variables, medical history, cardio-metabolic, and the ABCD2 scores (age, blood pressure, clinical features, symptom duration, and diabetes).

Results: Fifty-nine patients met the inclusion criteria. The prevalence of MR perfusion T_max ≥ 4 s ≥ 0 ml and ≥ 10 mL were 72.9% (43/59) and 42.4% (25/59), respectively. Multivariate analyses revealed that history of hypertension is an independent factor associated with MR perfusion abnormality (T_max ≥ 4 s ≥ 10 mL) for Chinese patients with TIA (P = 0.033, adjusted OR = 4.11, 95% CI = 1.12–15.11). Proximal artery stenosis (>50%) tended to lead to a larger PW lesion on MRI (p = 0.067, adjusted OR = 3.60, 95% CI = 0.91–14.20).

Conclusion: Our results suggest that the prevalence of perfusion abnormality is high as assessed by RAPID using the parametric T_max ≥ 4 s. History of hypertension is a strong predictor of focal perfusion abnormality as calculated by RAPID on T_max map of TIA patients with negative DWI findings.

Diagnostic Accuracy of the Explicit Diagnostic Criteria for Transient Ischemic Attack: A Validation Study

Supplemental Digital Content is available in the text.

Background and Purpose—

The clinical diagnosis of a transient ischemic attack (TIA) can be difficult. Evidence-based criteria hardly exist. We evaluated if the recently proposed Explicit Diagnostic Criteria for TIA (EDCT), an easy to perform clinical tool focusing on type, duration, and mode of onset of clinical features, would facilitate the clinical diagnosis of TIA.

Methods—

We used data from patients suspected of a TIA by a general practitioner and referred to a TIA service in the region of Utrecht, the Netherlands, who participated in the MIND-TIA (Markers in the Diagnosis of TIA) study. Information about the clinical features was collected with a standardized questionnaire within 72 hours after onset. A panel of 3 experienced neurologists ultimately determined the definite diagnosis based on all available diagnostic information including a 6-month follow-up period. Two researchers scored the EDCT. Sensitivity, specificity, and predictive values of the EDCT were assessed using the panel diagnosis as reference. A secondary analysis was performed with modified subcriteria of the EDCT.

Results—

Of the 206 patients, 126 (61%) had a TIA (n=104) or minor stroke (n=22), and 80 (39%) an alternative diagnosis. Most common alternative diagnoses were migraine with aura (n=24; 30.0%), stress related or somatoform symptoms (n=16; 20.0%), and syncope (n=9; 11.3%). The original EDCT had a sensitivity of 98.4% (95% CI, 94.4–99.8) and a specificity of 61.3% (49.7–71.9). Negative and positive predictive values were 96.1% (86.0–99.0) and 80.0% (75.2–84.1), respectively. The modified EDCT showed a higher specificity of 73.8% (62.7–83.0) with the same sensitivity and a similar negative predictive value of 96.7%, but a higher positive predictive value of 85.5% (80.3–89.5).

Conclusions—

The EDCT has excellent sensitivity and negative predictive value and could be a valuable diagnostic tool for the diagnosis of TIA.

Pre-existing White Matter Hyperintensity Lesion Burden and Diagnostic Certainty of Transient Ischemic Attack

GOALS

There are no validated biomarkers that allow for reliable distinction between TIA and other transient neurological symptoms that mimic TIA. We sought to determine whether the degree of pre-existing white matter hyperintensity (WMH) lesion burden relates to the diagnostic certainty of TIA in a cohort of patients presenting with transient neurological symptoms.

MATERIALS AND METHODS

We retrospectively analyzed 144 consecutive patients with available brain MRI to quantify and normalize the WMH volume for brain atrophy (adjusted white matter hyperintensity [aWMHV]). We first stratified subjects to probable (n = 62) versus possible (n = 82) TIA as per existing guidelines. Receiver-operating characteristic curves were used to determine a critical aWMHV-threshold (7.8 mL) that best differentiated probable from possible TIA. We then further stratified patients with possible TIA to likely (n = 52) versus unlikely (n = 30) TIA after independent chart review and adjudication. Finally, multivariable logistic and multinomial regression was used to determine whether the defined aWMHV independently related to probable and likely TIA after adjustment for pertinent confounders.

FINDINGS

With the exception of age (P < .001) and use of antiplatelets (P = .017), baseline characteristics were similar between patients with probable, likely, and unlikely TIA. In the fully adjusted multinomial model, the aWMHV cut-off greater than 7.8 mL (odds ratio 3.8, 95% confidence interval 1.3-10.9, P = .012) was significantly more frequent in patients with a probable TIA as compared to those with an unlikely TIA diagnosis.

CONCLUSIONS

We provide proof-of-principle that WMH may serve as a neuroimaging marker of diagnostic certainty of TIA after neurological workup has been completed.