The clinical significance of diffusion-weighted MR imaging in infratentorial strokes

Predictive Value of a Novel Baseline Diffusion-Weighted Imaging Posterior Circulation Score in Endovascular Treatment of Patients with Acute Vertebrobasilar Occlusion

RATIONALE AND OBJECTIVES

To investigate the predictive value of a novel posterior circulation score (novel-PC score) based on baseline posterior circulation diffusion-weighted imaging (DWI) for functional independence after endovascular treatment (EVT) in patients with acute vertebral-basilar artery occlusion (VBAO).

MATERIALS AND METHODS

The baseline DWI brain stem score (BSS), posterior circulation Alberta Stroke Program Early CT Score (pc-ASPECTS), and the novel-PC score were evaluated separately. A modified Rankin scale (mRS) ≤2 at 90 days was defined as a prognostic indicator of functional independence. Modified Thrombolysis in Cerebral Infarction grade 2b or 3 was defined as surgical success.

RESULTS

A total of 64 eligible patients were enrolled and divided into good and poor functional prognosis groups based on the mRS. The novel-PC score, BSS, and pc-ASPECTS (all P ≤ .001) were significantly better in the good functional prognosis group. The novel-PC score had a higher predictive value than BSS and pc-ASPECTS for 90-day functional independence (area under the receiver operating characteristic curve, 0.87 vs. 0.73 vs. 0.71; P < .05). Univariate binary logistic regression analysis showed that age (P = .006), Posterior National Institutes of Health Stroke Scale ≤18 (P < .001), BSS ≤2 (P = .008), pc-ASPECTS >7 (P = .002), and novel-PC score ≤5 (P = .001) were independently associated with function.

CONCLUSION

Our novel-PC score, based on DWI, can independently predict functional prognosis in patients with acute VBAO after EVT.

CLINICAL RELEVANCE

The novel-PC score based on baseline DWI was shown to be an independent predictor of function in patients with acute BVAO who are treated with EVT.

Imaging predictors of clinical outcomes after endovascular treatment in MRI-selected patients with acute basilar artery occlusion

PURPOSE

We aimed to investigate the impact of baseline infarct area and collateral status (CS), which are imaging predictors of clinical outcome following stroke, after endovascular treatment (EVT) in MRI-selected patients with acute basilar artery occlusion (BAO).

METHODS

Patients with acute BAO who underwent EVT within 24 h after stroke from December 2013 to February 2021 were included in this retrospective, multicenter, observational study. The baseline infarct area was evaluated by the posterior circulation of Acute Stroke Prognosis Early Computed Tomography Score (pc-ASPECTS) using diffuse-weighted imaging (DWI), and CS was assessed by measuring the computed tomography angiography of the basilar artery (BATMAN) score and the posterior circulation collateral score (PC-CS) using magnetic resonance angiography (MRA). A Good outcome was defined as a modified Rankin scale score ≤ 3 at 3 months. For each imaging predictor, a multivariate logistic regression analysis was performed to evaluate its impact on good outcomes.

RESULTS

A total of 86 patients were analyzed, and 37 (43.0%) had a good outcome. The latter showed significantly higher pc-ASPECTS than those without good outcomes. In multivariate analyses, a pc-ASPECTS ≥ 7 was significantly associated with good outcomes (OR, 2.98 [95% CI, 1.10-8.13], P = 0.032), while PC-CS ≥ 4 (OR, 2.49 [95% CI, 0.92-6.74], P = 0.073) and BATMAN score ≥ 5 (OR, 1.51 [95% CI, 0.58-3.98], P = 0.401) were not.

CONCLUSIONS

In MRI-selected patients with acute BAO, pc-ASPECTS on DWI was an independent predictor of clinical outcomes after EVT, while the MRA-based CS assessments were not.

CT Perfusion in Lacunar Stroke: A Systematic Review

BACKGROUND

The main theory underlying the use of perfusion imaging in acute ischemic stroke is the presence of a hypoperfused volume of the brain downstream of an occluded artery. Indeed, the main purpose of perfusion imaging is to select patients for endovascular treatment. Computed Tomography Perfusion (CTP) is the more used technique because of its wide availability but lacunar infarcts are theoretically outside the purpose of CTP, and limited data are available about CTP performance in acute stroke patients with lacunar stroke.

METHODS

We performed a systematic review searching in PubMed and EMBASE for CTP and lacunar stroke with a final selection of 14 papers, which were examined for data extraction and, in particular, CTP technical issues and sensitivity, specificity, PPV, and NPV values.

RESULTS

A global cohort of 583 patients with lacunar stroke was identified, with a mean age ranging from 59.8 to 72 years and a female percentage ranging from 32 to 53.1%.CTP was performed with different technologies (16 to 320 rows), different post-processing software, and different maps. Sensitivity ranges from 0 to 62.5%, and specificity from 20 to 100%.

CONCLUSIONS

CTP does not allow to reasonable exclude lacunar infarct if no perfusion deficit is found, but the pathophysiology of lacunar infarct is more complex than previously thought.

Prognostic value of pretreatment diffusion-weighted imaging score for acute basilar artery occlusion with successful endovascular recanalization

PURPOSE

The aim of this study is to test the prognostic value of a diffusion-weighted imaging (DWI) score in acute basilar artery occlusion (ABAO) with successful recanalization.

METHODS

The DWI-based pons-midbrain and thalamus (PMT) score was developed to assess posterior circulation infarcts. We test its prognostic value and compare it with other two established scales, the DWI-based posterior circulation acute stroke prognosis Early CT score (PC-ASPECTS) and brain stem score (BSS). A retrospective cohort of consecutive ABAO patients with pretreatment magnetic resonance imaging and successful recanalization (defined as modified Thrombolysis in Cerebral Infarction 2b-3) were analyzed. A favorable outcome was defined as a 90-day modified Rankin Scale (mRS) score of 2 or less. The prognostic performance of three scales was estimated by receiver operating characteristic (ROC) curve analyses.

RESULTS

One hundred and sixteen eligible patients (mean age, 59.1 ± 11.7 [standard deviation]; 96 [82.8%] man) were included and evaluated. Between favorable (mRS ≤ 2) and unfavorable groups, the baseline PMT score (median [interquartile range], 3 [1-4] versus 6 [5-8]; P < 0.001) differs significantly. ROC curve analyses showed the PMT score had the best prognostic value for favorable outcome (area under the curve, PMT versus BSS versus PC-ASPECTS = 0.80 versus 0.72 versus 0.68, P = 0.010). Multivariate logistic regression analyses showed baseline National Institute of Health stroke scale (OR, 0.90 [95%CI, 0.86-0.95], P = 0.004) and PMT score < 5 (OR, 17.83 [95%CI, 3.91-81.19], P < 0.001) were independent prognostic factors of favorable outcome.

CONCLUSIONS

The PMT score seems to predict clinical outcome of ABAO patients with successful recanalization.

White matter damage due to pulsatile versus steady blood pressure differs by vascular territory: A cross-sectional analysis of the UK Biobank cohort study

Small vessel disease is associated with age, mean blood pressure (MAP) and blood pressure pulsatility (PP). We used data from the UK Biobank cohort study to determine the relative importance of MAP versus PP driving white matter injury within individual white matter tracts, particularly in the anterior and posterior vascular territory. The associations between blood pressure and diffusion indices in 27 major tracts were analysed using unadjusted and fully-adjusted general linear models and mixed-effect linear models. Blood pressure and neuroimaging data were available for 37,041 participants (mean age 64+/-7.5 years, 53% female). In unadjusted analyses, MAP and PP were similarly associated with diffusion indices in the anterior circulation. In the posterior circulation, the associations were weaker, particularly for MAP. In fully-adjusted analyses, MAP remained associated with all diffusion indices in the anterior circulation, independently of age. In the posterior circulation, the effect of MAP became protective. PP remained associated with greater mean diffusivity and extracellular free water diffusion in the anterior circulation and all diffusion indices in the posterior circulation. There was a significant interaction between PP and age. This implies discordant mechanisms for chronic white matter injury in different brain regions and potentially in the associated stroke risks.

Predictive value of DWI posterior-circulation lesion volume for 90-day clinical outcome after endovascular treatment of acute basilar artery occlusion: a retrospective single-center study

PURPOSE

The relationship between posterior-circulation lesion volume (PCLV) and clinical outcomes is poorly investigated. We aimed to analyze, in patients with acute basilar artery occlusion (ABAO), if pre-endovascular treatment (EVT) PCLV was a predictor of outcomes.

METHODS

We analyzed consecutive MRI selected, endovascularly treated ABAO patients. Baseline PCLV was measured in milliliters on apparent diffusion-coefficient map reconstruction. Univariable and multivariable logistic models were used to test if PCLV was a predictor of 90-day outcomes. After the received operating characteristic (ROC) analysis, the optimal cut-off was determined to evaluate the prognostic value of PCLV.

RESULTS

A total of 110 ABAO patients were included. The median PCLV was 4.4 ml (interquartile range, 1.3-21.2 ml). Successful reperfusion was achieved in 81.8% of cases after EVT. At 90 days, 31.8% of patients had a modified Rankin scale ≤ 2, and the mortality rate was 40.9%. PCLV was an independent predictor of functional independence and mortality (odds ratio [OR]:0.57, 95% confidence interval [CI], 0.34-0.93 and 1.84, 95% CI, 1.23-2.76, respectively). The ROC analysis showed that a baseline PCLV ≤ 8.7 ml was the optimal cut-off to predict the 90-day functional independence (area under the curve [AUC] = 0.68, 95% CI, 0.57-0.79, sensitivity 88.6%, and specificity 49.3%). In addition, a PCLV ≥ 9.1 ml was the optimal cut-off for the prediction of 90-day mortality (AUC = 0.71, 95% CI, 0.61-0.82, sensitivity 80%, and specificity 60%).

CONCLUSIONS

Pre-treatment PCLV was an independent predictor of 90-day outcomes in ABAO. A PCLV ≤ 8.7 and ≥ 9.1 ml may identify patients with a higher possibility to achieve independence and a higher risk of death at 90 days, respectively.

Novel Diffusion-Weighted Imaging Score Showed Good Prognostic Value for Acute Basilar Artery Occlusion Following Endovascular Treatment: The Pons-Midbrain and Thalamus Score

BACKGROUND AND PURPOSE

Prognostic factors for outcome of endovascular treatment remains to be investigated in patients with acute basilar artery occlusion. We aimed to assess the prognostic value of a novel pretreatment diffusion-weighted imaging score: The Pons-Midbrain and Thalamus (PMT) score.

METHODS

Eligible patients who underwent endovascular treatment due to acute basilar artery occlusion were reviewed. The PMT score was a diffusion-weighted imaging-based semiquantitative scale in which the infarctions of pons, midbrain, and thalamus were fully considered. The PMT score was assessed as well as the posterior circulation Acute Stroke Prognosis Early Computed Tomography Score and Brain Stem Score. Good outcomes were defined as a modified Rankin Scale score of ≤3 at 90-day and successful reperfusion as Thrombolysis in Cerebral Infarction grades 2b/3. The associations between baseline clinical parameters and good outcomes were evaluated with logistic regression.

RESULTS

A total of 107 patients with pretreatment magnetic resonance imaging were included in this cohort. The baseline PMT score (median [interquartile range], 3 [1-5] versus 7 [5-9]; P<0.001) and Brain Stem Score (median [interquartile range], 2 [1-4] versus 3 [2-5]; P=0.001) were significantly lower in good outcome group; the posterior circulation Acute Stroke Prognosis Early Computed Tomography Score was higher in good outcome group without statistical significance. As a result of receiver operating characteristic curve analyses, the posterior circulation Acute Stroke Prognosis Early Computed Tomography Score showed poor prognostic accuracy for good outcome (area under the curve, 0.60 [95% CI, 0.49-0.71]; P=0.081); The baseline PMT score showed significantly better prognostic accuracy for 90-day good outcome than the Brain Stem Score and National Institutes of Health Stroke Scale (area under the curve, 0.80 versus 0.68 versus 0.78, P=0.003). In addition, favorable PMT score <7 (odds ratio, 22.0 [95% CI, 6.0-80.8], P<0.001), Brain Stem Score <3 (odds ratio, 4.65 [95% CI, 2.05-10.55], P<0.001) and baseline National Institutes of Health Stroke Scale <23 (odds ratio, 8.0 [95% CI, 2.5-25.6], P<0.001) were associated with improved good outcome.

CONCLUSIONS

In patients with acute basilar artery occlusion following endovascular treatment, the pretreatment diffusion-weighted imaging based PMT score showed good prognostic value for clinical outcome.

Added value in stroke imaging: accuracy and utility of additional coronal diffusion-weighted imaging

AIM

To evaluate the value of adding additional coronal diffusion-weighted imaging with the same section thickness as standard axial images to improve detection of small infarcts.

MATERIALS AND METHODS

Axial and coronal diffusion-weighted images (4 or 5 mm section thickness, 1 mm gap) were studied retrospectively in two rounds of data collection. During the first round, two radiologists identified sub-centimetre infarcts on only axial images during one sitting, and only coronal images during a second sitting. During the second round, the two radiologists were asked to identify infarcts on only axial images during one sitting, and on both axial and coronal images simultaneously during the second sitting. An expert reviewer determined true infarcts and artefacts. Relative contrast-to-noise ratios (rCNR) and relative mean region of interest (rROI) within each lesion were calculated.

RESULTS

During the first round, sensitivity for infarct detection for the two radiologists was 92.7% and 100% on axial and 95.1% and 92.7% on coronal, respectively. During the second round, sensitivity improved from 88.9% to 98.1% for both radiologists (p=0.03). Specificity improved but did not reach statistical significance (p=0.06 and 0.12). False-negative and false-positive lesions had lower rCNR and rROI values.

CONCLUSION

Including both axial and coronal DWI images with the same section thickness in the stroke protocol improves detection of small infarcts, which can be misdiagnosed on a single imaging plane. A second imaging plane is particularly useful for subtle infarcts, even without acquiring thin-section images.

Improved Detectability of Brain Stem Ischemia by Combining Axial and Coronal Diffusion-Weighted Imaging

BACKGROUND AND PURPOSE

To evaluate the benefit of a coronal diffusion-weighted imaging (DWI) in addition to standard axial DWI for the detection of brain stem infarctions.

METHODS

A retrospective analysis of patients with symptoms consistent with acute and subacute brain stem infarction who received magnetic resonance imaging, including axial and coronal DWI. Diffusion restrictions were identified by 2 independent raters blinded for the final clinical diagnosis in 3 separate reading steps: axial DWI, coronal DWI, and combined axial and coronal DWI. Lesion location and certainty level were both documented for each reading step. In cases of reader disagreement, an additional consensus reading was performed.

RESULTS

Two hundred thirty-nine patients were included. Of these, 124 patients (51.9%) were clinically diagnosed with brain stem infarction. Sensitivity, specificity, positive, and negative predictive values were best for combined DWI assessment (90.3%, 99.1%, 99.1%, and 90.5%) compared with axial (85.5%, 94.9%, 94.6%, and 85.8%) and coronal DWI alone (87.9%, 96.5%, 96.5%, and 88.1%). Diffusion restriction on combined DWI was diagnosed in 112/124 patients compared with 106/124 on axial DWI and 109/124 on coronal DWI. Interobserver agreement for the detection of brain stem lesions was the highest in the combined rating step (Cohen κ coefficient=0.94).

CONCLUSIONS

Coronal DWI sequences might improve the detection rate of brain stem infarction compared with standard axial DWI. The combined coronal and axial DWI provides the best detection rate while minimally increasing scan times.

Multimodal CT pc-ASPECTS in infratentorial stroke: diagnostic and prognostic value

BACKGROUND AND PURPOSE

Diagnosis of posterior circulation stroke may be challenged. National Institutes of Health Stroke Scale (NIHSS) and brain imaging (non-contrast brain computed tomography-CT) are used for diagnosis; evaluation on posterior circulation stroke remains a limit of NIHSS, and the value of non-contrast CT (NCCT) is limited due to artifacts caused by the bones of the base of the skull. We tested the validity and prognostic value of posterior circulation Alberta Stroke Program Early CT Score (pc-ASPECTS) in patients with posterior circulation stroke.

METHODS

Pc-ASPECTS allots the posterior circulation 10 points. We studied 50 patients with posterior circulation stroke. We applied pc-ASPECTS to NCCT, CT angiography, and CT Perfusion. We evaluated the correlation of pc-ASPECT with outcome parameters for stroke.

RESULTS

Out of 50 patients, CTP showed abnormalities in 34 cases. The pc-ASPECT score calculated on brain CT and on the brain CT + angio CT had a sensibility of 24%, calculated on brain CT, angio CT and CTPerfusion gain a sensibility of 72%. Pc-ASPECT MTT resulted to be the more reliable parameter: outcome given by NIHSS score at discharge, mRS at discharge, and at 3 months was more severe in patients with Pc-ASPECT MTT alteration. Outcome given by NIHSS score at discharge and mRS at discharge and 1 at 3 months was more severe in patients with higher NIHSS score at admission.

CONCLUSION

We evaluated the usefulness of pc-ASPECTS on CTP in predicting functional outcome in acute posterior circulation stroke that appears to be a powerful marker for predicting functional outcome.

Predictive value on diffusion weighted imaging scores for basilar artery occlusion after endovascular treatment

PURPOSE

To assess the predictive value of three scoring systems based on diffusion weighted imaging in basilar artery occlusion patients after endovascular treatment.

METHODS

We analyzed clinical and radiological data of patients with basilar artery occlusion from January 2010 to June 2019, with modified Rankin Scale of 0-2 and 3-6 defined as favorable outcome and unfavorable outcome at three months. Diffusion weighted imaging posterior circulation ASPECTS Score (DWI pc-ASPECT Score), Renard diffusion weighted imaging Score, and diffusion weighted imaging Brainstem Score were used to evaluate the early ischemic changes.

RESULTS

There were a total of 88 basilar artery occlusion patients enrolled in the study after endovascular treatment, with 33 of them getting a favorable outcome. According to the analysis, the time from onset to puncture within 12 h (odds ratio: 4.34; 95% confidence interval: 1.55-12.16; P = 0.01), presence of collateral flow via PCoA (odds ratio: 0.31; 95%CI: 0.12-0.79; P = 0.01) or between PICA and SCA (odds ratio: 0.18; 95%CI: 0.07-0.47; P = 0.00), equal or less than 15 points on baseline NIHSS (area under the curve 0.79, 95% CI 0.69-0.89; sensitivity = 69.1%, specificity = 81.8%; P = 0.00), and equal or less than 1.5 points on diffusion weighted imaging Renard score (area under the curve 0.63, 95% CI 0.51-0.75; sensitivity = 83.6%, specificity = 39.4%; P = 0.046) were independently associated with favorable outcome.

CONCLUSIONS

Renard diffusion weighted imaging score may be an independent predictor of functional outcome in basilar artery occlusion patients after endovascular treatment.

Sagittal diffusion-weighted imaging in preventing the false-negative diagnosis of acute brainstem infarction: Confirmation of the benefit by anatomical characterization of false-negative lesions

Background:

In some cases of acute brainstem infarction (BI), standard axial diffusion-weighted imaging (DWI) does not show a lesion, leading to false-negative (FN) diagnoses. It is important to recognize acute BI accurately and promptly to initiate therapy as soon as possible.

Methods:

Of the 171 patients with acute cerebral infarctions in our institution who were examined, 16 were diagnosed with true-positive BI (TP-BI) and six with FN-BI. We evaluated the effectiveness of sagittal DWI in accurately diagnosing acute BI and sought to find the cause of its effectiveness by the anatomical characterization of FN-BIs.

Results:

Considering the direction of the brainstem perforating arteries, we supposed that sagittal DWI might more effectively detect BIs than axial DWI. We found that sagittal DWI detected all FN-BIs more clearly than axial DWI. The mean time between the onset of symptoms and initial DWI was significantly longer in the TP group (17.6 ± 5.5 h) than in the FN group (5.0 ± 1.2 h; P < 0.0001). The lesion volumes were much smaller in FN-BIs (259 ± 82 mm³) than in TP-BIs (2779 ± 767 mm³; P = 0.0007). FN-BIs had a significant inverse correlation with the ventrodorsal length of infarcts (FN 3.5 ± 1.1 mm, TP 11.4 ± 3.6 mm; P < 0.0004) and no correlation with other size parameters such as rostrocaudal thickness and lateral width.

Conclusion:

Anatomical characterization clearly confirmed that the addition of sagittal DWI to the initial axial DWI in suspected cases of BI ensures its accurate diagnosis and improves the patient’s prognosis.

Improved detectability of acute and subacute brainstem infarctions by combining standard axial and thin-sliced sagittal DWI

BACKGROUND AND PURPOSE

Most false negative findings in DWI of ischemic stroke are in patients with minor deficits clinically localized to the brainstem. Our goal was to evaluate the benefit of a thin-sliced sagittal DWI in addition to conventional axial DWI at 1.5T for the detection of brainstem infarctions.

METHODS

Data of patients with symptoms consistent with acute and subacute brainstem infarction and an MRI examination including standard axial DWI and thin-sliced sagittal DWI were retrospectively analyzed. Patients with the later diagnosis of a TIA, an inflammation or a tumor of the brainstem were excluded from analysis. Diffusion restrictions were identified by two independent raters blinded for the final clinical diagnosis in three separate reading steps: First, only axial DWI, secondly only sagittal DWI, and lastly both DWIs together. Presence and size of DWI-lesions were documented for each plane. Differences between the observers were settled in consensus in a separate joint reading.

RESULTS

Of 73 included patients, 46 patients were clinically diagnosed with brainstem infarction. Inter-observer agreement was excellent for the detection of brainstem lesions in axial and sagittal DWI (kappa = 0.94 and 0.97). In 28/46 patients (60.9%) lesions were detected in the axial plane alone, whereas in 6 more patients (73.9%) lesions were detected in the review of both sequences together. All lesions undetectable in the axial plane were smaller than 5 mm in cranio-caudal direction.

CONCLUSIONS

Thin-sliced sagittal DWI in addition to axial DWI improves the detection rate of brainstem infarction with little additional expenditure of time.

Stepwise Rostrocaudal Brainstem Anesthesia as a Complication of Local Anesthesia: A Case Report

Iatrogenic cranial nerve palsies can rarely complicate neurosurgical, oral maxillofacial, and otolaryngological procedures. Among the most serious complications of cranial nerve palsy is upper airway obstruction, which is life threatening. We present a case of multiple cranial nerve palsies evolving rapidly in a rostrocaudal stepwise fashion after infiltration of lidocaine to repair a cerebrospinal fluid leak in a patient postoccipital craniectomy. This led to hypoxic respiratory failure requiring mechanical ventilation before resolving spontaneously. This is the first known case of accidental brainstem anesthesia secondary to lidocaine infiltration at an occipital craniectomy site and serves to caution clinicians who manage similar patients.

Characteristics associated with outcome in patients with first-ever posterior fossa stroke

BACKGROUND AND PURPOSE

Factors such as infarct volume, infarct location and symptom severity can considerably influence long-term outcome in posterior fossa strokes. The decision about therapy can sometimes be complicated by discrepancies between infarct volume and clinical severity. We aimed to evaluate imaging and clinical parameters possibly influencing long-term outcome in patients with first-ever posterior fossa stroke.

METHODS

Imaging was performed on a 3-T magnetic resonance imaging scanner. Sixty-one of 1795 patients from the observational 1000Plus and LOBI studies (NCT00715533 and NCT02077582, clinicaltrials.org) were enrolled, meeting the inclusion criteria of first-ever posterior fossa stroke and magnetic resonance imaging examination within 24 h after symptom onset. Infarcts were classified as belonging to a proximal, middle or distal territory location in the posterior fossa. Good outcome was defined as a modified Rankin scale score of ≤1 at 3 months.

RESULTS

The largest lesion volumes on diffusion-weighted imaging on day 0 and fluid attenuation inversion recovery (FLAIR) on day 6 were found in the middle territory location with a median volume of 0.4 mL on diffusion-weighted imaging and 1.0 mL on FLAIR on day 6 versus 0.1/0.3 mL in the proximal and 0.1/0.1 mL in the distal territory location of the posterior fossa, respectively. Parameters associated with poor outcome were older age (P = 0.005), higher National Institutes of Health Stroke Scale score on admission/discharge (P = 0.016; P = 0.001), larger lesion volumes on FLAIR on day 6 (P = 0.013) and dysphagia (P = 0.02). There was no significant association between infarct location and modified Rankin scale score on day 90.

CONCLUSION

Infarct volume and clinical severity, but not infarct location, were the main contributors to poor long-term outcome in first-ever posterior fossa strokes.

Predictors for Intracranial Hemorrhage Following Intravenous Thrombolysis in Posterior Circulation Stroke

Intravenous thrombolysis (IVT) is a standard treatment for anterior (ACS) and posterior circulation stroke (PCS). However, due to the low occurrence of PCS and of intracranial hemorrhage (ICH) in PCS, the knowledge about ICH predictors following IVT in PCS is sparse. Our aim was to identify predictors for ICH following IVT in PCS. The set consisted of 1281 consecutive ischemic stroke (IS) patients treated with IVT, out of which 158 (103 males; mean age 65.6 ± 12.3 years) had PCS. Collected data include baseline characteristics, common stroke risk factors, pre-medication, stroke severity, admission blood glucose level, blood pressure and treatment with intravenous antihypertensive therapy before and during IVT, occlusion of arteries, recanalization rate, time to treatment, and clinical outcome at day 90. Overall, 11 (7%) patients had ICH. Atrial fibrillation (p = 0.004), neurological deficit at time of treatment in the National Institutes of Health Stroke Scale (p = 0.016), decreased level of consciousness (p = 0.003), occlusion of basilar artery (p = 0.007), occlusion of PCA (p = 0.001), and additional endovascular therapy (p = 0.001) were identified by logistic regression analysis as significant predictors for ICH in PCS. Patients with ischemic lesion in the brainstem, occlusion of vertebral artery, or absence of basilar and posterior cerebral artery occlusion might be considered for treatment with IVT even in borderline cases. Those patients seem to have less frequently favorable outcomes without an increase in ICH rate. Time to IVT in PCS seems not to influence ICH risk or chances for favorable outcomes as significantly as it does in ACS.

Lesions on DWI and the Outcome in Hyperacute Posterior Circulation Stroke

BACKGROUND

few studies have addressed the association between the characteristics of ischemic lesions detected by diffusion-weighted imaging (dWi) and the clinical outcome in patients with hyperacute posterior circulation ischemic stroke. this study demonstrates a relationship between the findings assessed by dWi and the outcome in patients with hyperacute posterior circulation ischemic stroke.

METHODS

We reviewed data from 118 patients who had posterior circulation ischemic stroke within six hours from the onset of their symptoms. the clinical outcome included early neurological deterioration (end) and a favorable outcome at three months after the onset of symptoms. using dWi, the lesion volume and the number and location of injured anatomical regions were analyzed to evaluate whether the results correlated with the clinical outcome measures.

RESULTS

the number of injured anatomical regions assessed by dWi was associated with the initial and delayed neurological status. Both the total volume and the number of injured anatomical regions associated with end and a favorable outcome. analysis of the location of the injured regions determined that only a pontine lesion independently associated with end. interestingly, four out of five patients who underwent decompressive craniectomy exhibited a large infarction volume but minor symptoms.

CONCLUSIONS

in patients with hyperacute posterior circulation ischemic strokes, the lesions assessed by dWi were associated with the clinical outcome, regardless of the initial neurological status. dWi is an effective initial imaging tool for assessing the extent of lesions and clinical outcomes in patients with hyperacute posterior circulation ischemic stroke.

Posterior vs. anterior circulation infarction: demography, outcomes, and frequency of hemorrhage after thrombolysis

BACKGROUND

Intravenous thrombolysis is considered to be the standard specific reperfusion therapy in acute ischemic stroke in both anterior and posterior cerebral circulation.

AIMS

Our aim was to evaluate the 90-day outcome and rate of intracranial hemorrhage after recombinant tissue plasminogen activator administration in posterior circulation stroke and to compare the intracranial hemorrhage risk for posterior circulation stroke and anterior circulation stroke.

METHODS

The set consisted of 877 consecutive acute ischemic stroke patients (777 anterior circulation stroke; 100 posterior circulation stroke) who underwent intravenous thrombolysis with recombinant tissue plasminogen activator in a standard dose of 0·9 mg/kg. The role of following factors was assessed: presenting characteristics, intracranial hemorrhage classification according to ECASS I, mortality, and 90-day clinical outcome assessed using the modified Rankin scale.

RESULTS

Good clinical outcomes (modified Rankin scale 0-2) were noted in 59% of posterior circulation stroke patients, with a mortality rate of 19%. Intracerebral hemorrhage was significantly less frequent in posterior circulation stroke than in anterior circulation stroke patients (5·1 vs. 17·2%; P = 0·002). The risk of large hemorrhage (parenchymal hematoma 1 and 2) was 5·2 times higher in anterior circulation stroke patients (P = 0·007). The following additional statistically significant differences were found between posterior circulation stroke and anterior circulation stroke patients: median age, male gender, presence of atrial fibrillation, hyperlipidemia, median time to treatment, and median blood glucose level on admission.

CONCLUSIONS

Our study suggests that posterior circulation stroke is associated with a lower risk of intracranial hemorrhage than anterior circulation stroke is.

Younger Stroke Patients With Large Pretreatment Diffusion-Weighted Imaging Lesions May Benefit From Endovascular Treatment

BACKGROUND AND PURPOSE

Lesion volume on diffusion-weighted magnetic resonance imaging (DWI) before acute stroke therapy is a predictor of outcome. Therefore, patients with large volumes are often excluded from therapy. The aim of this study was to analyze the impact of endovascular treatment in patients with large DWI lesion volumes (>70 mL).

METHODS

Three hundred seventy-two patients with middle cerebral or internal carotid artery occlusions examined with magnetic resonance imaging before treatment since 2004 were included. Baseline data and 3 months outcome were recorded prospectively. DWI lesion volumes were measured semiautomatically.

RESULTS

One hundred five patients had lesions >70 mL. Overall, the volume of DWI lesions was an independent predictor of unfavorable outcome, survival, and symptomatic intracerebral hemorrhage (P<0.001 each). In patients with DWI lesions >70 mL, 11 of 31 (35.5%) reached favorable outcome (modified Rankin scale score, 0-2) after thrombolysis in cerebral infarction 2b-3 reperfusion in contrast to 3 of 35 (8.6%) after thrombolysis in cerebral infarction 0-2a reperfusion (P=0.014). Reperfusion success, patient age, and DWI lesion volume were independent predictors of outcome in patients with DWI lesions >70 mL. Thirteen of 66 (19.7%) patients with lesions >70 mL had symptomatic intracerebral hemorrhage with a trend for reduced risk with avoidance of thrombolytic agents.

CONCLUSIONS

There was a growing risk for poor outcome and symptomatic intracerebral hemorrhage with increasing pretreatment DWI lesion volumes. Nevertheless, favorable outcome was achieved in every third patient with DWI lesions >70 mL after successful endovascular reperfusion, whereas after poor or failed reperfusion, outcome was favorable in only every 12th patient. Therefore, endovascular treatment might be considered in patients with large DWI lesions, especially in younger patients.

Ischemic posterior circulation stroke: a review of anatomy, clinical presentations, diagnosis, and current management

Posterior circulation strokes represent approximately 20% of all ischemic strokes (1, 2). In contrast to the anterior circulation, several differences in presenting symptoms, clinical evaluation, diagnostic testing, and management strategy exist presenting a challenge to the treating physician. This review will discuss the anatomical, etiological, and clinical classification of PC strokes, identify diagnostic pitfalls, and overview current therapeutic regimens.

Diffusion-weighted imaging score of the brain stem: A predictor of outcome in acute basilar artery occlusion treated with the Solitaire FR device

BACKGROUND AND PURPOSE

The prognosis for ischemic stroke due to acute basilar artery occlusion is very poor: Early recanalization remains the main factor that can improve outcomes. The baseline extent of brain stem ischemic damage can also influence outcomes. We evaluated the validity of an easy-to-use DWI score to predict clinical outcome in patients with acute basilar artery occlusion treated by mechanical thrombectomy.

MATERIALS AND METHODS

We analyzed the baseline clinical and DWI parameters of 31 patients with acute basilar artery occlusion, treated within 24 hours of symptom onset by using a Solitaire FR device. The DWI score of the brain stem was assessed with a 12-point semiquantitative score that separately considered each side of the medulla, pons, and midbrain. Clinical outcome was assessed at 180 days by using the mRS. According to receiver operating characteristic analyses, the cutoff score determined the optimal positive predictive value for outcome. The Spearman rank correlation coefficient assessed the correlation between the DWI brain stem score and baseline characteristics.

RESULTS

Successful recanalization (Thrombolysis in Cerebral Infarction 3-2b) was achieved in 23 patients (74%). A favorable outcome (mRS ≤ 2) was observed in 11 patients (35%). An optimal DWI brain stem score of <3 predicted a favorable outcome. The probability of a very poor outcome (mRS ≥ 5) if the DWI brain stem score was ≥5 reached 80% (positive predictive value) and 100% if this score was ≥6. Interobserver reliability of the DWI brain stem score was excellent, with an intraclass correlation coefficient of 0.97 (95% CI, 0.96-0.99). The DWI brain stem score was significantly associated with baseline tetraplegia (P = .001) and coma (P = .005).

CONCLUSIONS

In patients with acute basilar artery occlusion treated by mechanical thrombectomy, the baseline DWI brain lesion score seems to predict clinical outcome.

Misdiagnosis of stroke

Rapid diagnosis of stroke is necessary for the timely delivery of thrombolysis and evaluation of novel therapies such as neuroprotection. An accurate clinical history and competent examination are key to identifying which patients are likely to have had a stroke and arranging and interpreting neuroimaging. Stroke symptoms are typically acute in onset, but are highly variable depending on the vascular territory affected. Common presenting symptoms are limb weakness, and speech and visual disturbances. Common stroke mimics are seizures, space occupying lesions, syncope, somatization and delirium secondary to sepsis. Stroke recognition instruments can help nonspecialists in the early diagnosis of stroke, with studies reporting sensitivity of over 90% and specificity of approximately 85% for some instruments. In patients with a clinical diagnosis of stroke, brain computed tomography or MRI is required to exclude some stroke mimics and differentiate ischemic from hemorrhagic stroke, which is key to providing appropriate therapies such as thrombolysis. In the future, plasma biomarkers may improve clinical diagnosis of stroke, but prospective studies are required to establish their utility. Clinical trials of acute stroke therapies need to ensure rapid accurate diagnosis of stroke using structured clinical assessments and appropriate imaging to achieve early treatment and avoid entry of stroke mimics into trials.

Characteristics of central lesions in patients with dizziness determined by diffusion MRI in the emergency department

BACKGROUND

To describe the rate and risk factors of central lesions among patients with dizziness in the emergency department based on diffusion-weighted MRI, which otologists consulted for evaluation of patients with dizziness need to know.

METHODS

902 Consecutive patients who presented with dizziness symptoms as a chief complaint in the emergency department (ED) of our tertiary referral centre between January 2011 and June 2011 were studied. Central lesions were confirmed by diffusion-weighted MRI. Univariate and multivariate analyses were used for factors predictive of central lesions.

RESULTS

Of 645 patients who underwent MRI, 23 (3.6%) had acute central lesions (22 infarcts/1 haemorrhage). Univariate analyses revealed that older age, hypertension, atrial fibrillation, non-whirling type of dizziness symptoms and combined neurological symptoms were significantly associated with the development of central lesions (p<0.05). The incidence of central lesions in patients aged in their 40s, 50s, 60s, 70s and ≥80s was 0, 3.9%, 3.4%, 7.4% and 16.7%. Multivariate analyses showed that hypertension (p=0.01, OR=3.42), symptoms of non-whirling type (p=0.03, OR=3.12) and combined neurological symptoms (p<0.01, OR=16.72) were independent predictors of central lesions.

CONCLUSIONS

Although dizziness in the ED is generally benign, the prevalence of acute central lesions was 3.6% among 645 patients with dizziness who underwent MRI. Old age (>50 years), hypertension, non-whirling type of dizziness symptoms and associated neurological symptoms were significant risk factors for central lesions.

The relatively good outcome of cerebellum-brainstem ischemic strokes

BACKGROUND

Our clinical experience suggests that the outcome of cerebellum-brainstem ischemic strokes is better than that of hemispheric ischemic strokes.

METHODS

Within the setting of 2 national Israeli prospective stroke surveys, we analyzed risk factors, etiology, severity at presentation, and prognosis of first ischemic cerebellum-brainstem stroke (259 patients), comparing with strokes within the anterior circulation (1,029 patients).

RESULTS

Patients with cerebellum-brainstem strokes were younger and had less frequently atrial fibrillation and congestive heart failure. Cardioembolic etiology was significantly less prevalent (p < 0.001). Severity at presentation was milder (p < 0.001). At discharge, worsening of the modified Rankin Scale was present in a smaller number of patients (p < 0.001); more returned to their home (p < 0.001). Six-month and 1-year mortality were lower (p < 0.001 for both). Adjusted logistic regression models showed that patients with cerebellum-brainstem strokes had 50% smaller chances of dying (OR 0.55; 95% CI 0.31-0.98) and a smaller chance of worsening of the modified Rankin Scale at discharge (OR 0.61; 95% CI 0.46-0.82).

CONCLUSIONS

Cerebellum-brainstem strokes are less frequently cardioembolic, have a less severe presentation, and carry a better immediate and long-term prognosis.

Application of beta regression to analyze ischemic stroke volume in NINDS rt-PA clinical trials

BACKGROUND AND PURPOSE

Ischemic stroke lesion volumes have proven difficult to analyze due to the extremely skewed shape of their underlying distribution. We introduce an extension of generalized linear models, beta regression, as a possible method of modeling extremely skewed distributions as evidenced in ischemic stroke lesion volumes.

METHODS

The NINDS rt-PA clinical trials measured ischemic stroke lesion volume as a secondary trial outcome. Three-month lesion volumes from these trials were analyzed using beta regression. A multi-variable regression model associating explanatory variables with ischemic stroke lesion volumes was constructed using accepted model building strategies and compared with the previously published volumetric analysis.

RESULTS

Beta regression produced a similar model when compared to the previous analysis published by the study group. All previously identified variables of importance were detected in the model building process. The age by treatment interaction described in previous studies was also found in this analysis, confirming the strong effect age has on stroke outcomes. Further, a treatment effect was elicited in terms of odds ratios, yielding a previously unknown quantification of the effect of rt-PA on lesion volumes.

CONCLUSIONS

Beta regression proved adept in modeling ischemic stroke lesions and offered the interpretation of covariates in terms of odds ratios. Beta regression is seen as a legitimate alternative to analyze ischemic stroke volumes.

Outcomes of intravenous thrombolysis in posterior versus anterior circulation stroke

BACKGROUND AND PURPOSE

Intravenous thrombolysis is an approved treatment for anterior (ACS) and posterior (PCS) circulation stroke. However, no randomized controlled trial has investigated safety and efficacy of intravenous thrombolysis according to stroke territory, although PCS is assumed to differ from ACS in many ways. We aimed to compare the safety and clinical outcome of intravenous thrombolysis applied to patients with PCS and ACS.

METHODS

Prospectively collected data of 883 consecutive patients with acute ischemic stroke (788 ACS, 95 PCS) treated with intravenous thrombolysis in 3 Swiss stroke centers were analyzed. Presenting characteristics, symptomatic intracranial hemorrhage, mortality, and favorable outcome (modified Rankin scale 0 or 1) at 3 months were compared between patients with PCS and ACS.

RESULTS

As compared with patients with ACS, those with PCS were younger (mean age, 63 versus 67 years, P=0.012) and had a lower mean baseline National Institutes of Health Stroke Scale score (9 versus 12, P<0.001). Patients with PCS less often had symptomatic intracranial hemorrhage (0% versus 5%, P=0.026) and had more often a favorable outcome (66% versus 47%, P<0.001). Mortality was similar in the 2 groups (PCS, 9%; ACS, 13%; P=0.243). After multivariable adjustment, PCS was an independent predictor of lower symptomatic intracranial hemorrhage frequency (P=0.001), whereas stroke territory was not associated either with favorable outcome (P=0.177) or with mortality (P=0.251).

CONCLUSIONS

Our study suggests that PCS is associated with a lower risk of symptomatic intracranial hemorrhage after intravenous thrombolysis as compared with ACS, whereas favorable outcome and mortality were similar in the 2 stroke territories.

False-negative diffusion-weighted MRI in acute cerebellar stroke

OBJECTIVE

To heighten physician awareness of false-negative diffusion-weighted (DW) magnetic-resonance imaging findings in patients with acute cerebellar infarction and the importance of periodically observing nystagmus after symptom onset.

METHODS

Between April 2007 and March 2010, we retrospectively reviewed the medical records of eight patients who had all complained of severe isolated vertigo or dizziness, and had visited an emergency department within 2-6h of its onset. Intracranial findings on initial magnetic resonance imaging (MRI) were normal. All patients had consulted our department for peripheral vestibular disorders. We periodically observed spontaneous and positional nystagmus 6-24h after symptom onset.

RESULTS

In three of the patients, the direction and/or type of nystagmus changed periodically. In four of the patients, severe vertigo, nausea, and vomiting persisted after the nystagmus had been resolved. A repeat MR examination was performed 24h after symptom onset because of the atypical pattern of nystagmus for benign peripheral vestibular disorders, at which point cerebellar infarction was detected.

CONCLUSIONS

Physicians who examine patients with acute severe isolated vertigo or dizziness should consider the possibility of false-negative DW MRI findings in case of hyperacute ischemic stroke. It is important to observe the nystagmus periodically after onset. The MR examination should be repeated more than 24h after symptom onset in patients with an atypical pattern of nystagmus for benign peripheral vestibular disorders.

DWI Reversibility after Intra-Arterial Thrombolysis. A Case Report and Literature Review

We report our case and review the literature on reversal DWI lesions, ADC thresholds and correlation between DWI lesion and outcome measured with clinical scales. A 30-years old woman was admitted to our hospital 18 hours after stroke onset. Considering the absence of alterations on CT and the worsening of symptomatology, the patient underwent MRI, which showed a slightly hyperintense signal in FLAIR images in the left portion of the pons and midbrain and a more evident bilateral DWI hyperintensity of the pons. The patient was treated with mechanical and pharmacological intra-arterial thrombolysis. The patient showed a rapid improvement of symptoms. Two weeks after the treatment her clinical conditions were characterized by a residual right hemiparesis and complete recovery of right motility, respiratory and swallowing difficulties. MR examination demonstrated a slight signal alteration of the pons left hemiportion and a disappearance of the mesencephalic signal alteration and of the right portion of the pons. DWI lesions represent irreversibly damaged tissue but new evidence suggests that DWI lesions may be reversible, especially with reperfusion, by now well demonstrated in animal models. Therefore acute DWI lesions probably contain not only irreversibly injured tissue but also parts of the penumbra. The debate on the capability of ADC maps to discriminate irreversibly from reversibly damaged tissue is a matter of controversy. ADC values in human stoke are not an independent indicator of tissue viability. The use of thresholds may improve reproducibility but not validity.

MRI detection of the cerebellar syndrome in Creutzfeldt-Jakob disease

Creutzfeldt-Jakob Disease (CJD) is characterized by bilateral basal ganglia hyperintensities on T2W and diffusion-weighted imaging (DWI) magnetic resonance imaging (MRI) scans, consistent with its extrapyramidal neurological manifestations. MRI is diagnostically uninformative about the cerebellar symptoms, equally prominent in CJD. This study was undertaken to explain this apparent paradox. Eleven CJD patients with definite cerebellar or brain stem symptoms were selected from a large prospective study, as well as 11 healthy controls matched for age and gender. All subjects participated in a standardized MRI protocol, including SPGR, fluid-attenuated inversion recovery (FLAIR), DWI and diffusion tensor imaging (DTI). All subjects underwent detailed examination by a neurologist blinded to the radiological findings, who predicted the expected site of cerebral abnormalities. MRI showed good sensitivity for the abnormalities predicted in the cortex (80-90%) and basal ganglia (100%). None of the standard MRI sequences, including DWI, DTI, and FLAIR, revealed any tissue abnormalities in cerebellum or brain stem. Apparent diffusion coefficient (ADC) values, however, were substantially and significantly elevated in several cerebellar structures, where also the volumetric (VBM) analysis revealed elevated cerebrospinal fluid volume, suggesting focal cerebellar atrophy in these CJD patients. In patients with CJD, DWI appears sensitive to the reduced diffusivity in cortex and basal ganglia but insensitive to cerebellar involvement. We propose that the radiological hallmark of cerebellar pathology in CJD is atrophy, revealed quantitatively by both VBM and elevated diffusivity, which is identifiable on ADC maps but poorly visualized in nonquantitative DWI images.

Rehabilitative outcome in supratentorial and infratentorial stroke: the role of motor deficits

BACKGROUND AND AIMS

There are few studies on the functional outcome of patients with supratentorial (STS) and infratentorial stroke (ITS). They lead to conflicting conclusions and do not define the role of motor deficits on functional recovery of STS and ITS patients. We wished to investigate this.

METHODS

The study was carried out on 90 consecutive patients admitted to our Rehabilitation Department with clinical evidence of acute cerebrovascular accident. Neuroimaging data, clinical evidence, and the National Institute of Health Stroke Scale (NIH) were used to select two groups of patients: 1) 45 patients with supratentorial stroke lesion (STS group), 2) 45 patients with infratentorial stroke lesion (ITS group). The STS group included patients with hemiparesis, and the ITS group patients with ataxia. Patients were evaluated through the NIH, Fugl-Meyer scale, Klockgether score, CIRS, Trunk Control Test (TCT), Lindmark scale, Barthel index, and Katz index, at both admission and discharge.

RESULTS

At admission, there were no differences between the STS and ITS groups in disability or average Barthel, Lindmark and Katz scores. At discharge, the Katz index average scores were significantly higher (p=0.000) and disability was lower (p=0.002) in ITS patients. The efficiency in Lindmark, Barthel and Katz scores of group ITS was significantly greater than that of STS patients (p=0.003, p=0.030 and p=0.000, respectively). The final Katz score was correlated (Spearman rank method) with initial TCT (p=0.000), onset to admission interval (p=0.019) and initial NIH (p=0.044) in the STS group. Final BADL score was correlated only with initial TCT (p=0.000) in the ITS group.

CONCLUSIONS

Our data seem to indicate that STS has a worse rehabilitative prognosis than ITS, and that hemiparesis is more difficult to rehabilitate than ataxia.

Diffusion-negative MRI in acute ischemic stroke: a case report

Background

Diffusion-weighted magnetic resonance imaging is a very sensitive tool for the early diagnosis of acute ischemic stroke. This is employed in some stroke centers as the primary screening tool to select patients eligible for thrombolysis.

Methods

We present the case of a 49-years old Chinese man whose diffusion-weighted magnetic resonance imaging performed 12 hours of symptom onset was negative.

Results

Although the initial diffusion-weighted magnetic resonance imaging was negative, the imaging repeated after 4 days despite static neurological symptoms and signs, could demonstrate an acute medullary infarction.

Conclusion

Diffusion-weighted imaging may not be100% sensitive in very early stages, especially in posterior circulation strokes. Our case serves as a reminder that clinical assessment still retains priority until a diagnostic modality offering 100% sensitivity and specificity is discovered.

Mechanism of multiple infarcts in multiple cerebral circulations on diffusion-weighted imaging

Acute multiple infarcts in multiple cerebral circulations (AMIMC) are thought to suggest the presence of cardioembolic sources or systemic hypercoagulopathy. However, the mechanism and the simultaneous occurrence of AMIMC are not well known. We reviewed 685 consecutive acute ischemic stroke patients who underwent diffusion-weighted imaging (DWI) within 48 hours of onset. AMIMC was defined as multiple acute DWI lesions distributed in more than one cerebral circulation (i.e., 2 anterior and 1 posterior circulations). Signal intensities on apparent diffusion coefficient (ADC) maps corresponding to acute DWI lesions were classified as 'low', 'iso-' or 'high' signals. Blood markers obtained within 24 hours after admission were compared between patients with and without AMIMC. Sixty-seven (9.8%) patients had AMIMC. Frequency of cardioembolism in AMIMC patients was only 29.9% (20/67), which was not different from non-AMIMC patients (21.7%, p = 0.16). Large-artery atherosclerosis (LAA) or small-vessel occlusion (SVO) in multiple circulations or combined LAA and SVO were identified in 34.3% (23/ 67) of AMIMC patients, although pure LAA and pure SVO were less frequent than in non-AMIMC patients. ADC signals were purely 'low' in 38 (56.7%) and 'mixed' (low with iso- or high) in 29 (43.3%). Cardioembolism tended to be associated with 'low' ADC signals (75.0%) compared with other stroke mechanisms (48.9%; p = 0.062). C-reactive protein was higher in AMIMC than in non- AMIMC patients (p = 0.009). Stroke mechanisms responsible for AMIMC are heterogeneous. ADC findings suggest that AMIMC commonly occur stepwise and may be useful in determining stroke mechanism. Systemic inflammation may be associated with the pathogenesis of AMIMC.

Diffusion-Weighted Imaging in Stroke Attributable to Patent Foramen Ovale

BACKGROUND AND PURPOSE

Patent foramen ovale (PFO) is an established cause of stroke in young patients without other determined etiologies (ie, cryptogenic stroke). The additional presence of atrial septum aneurysm (ASA) possibly increases stroke risk, but it remains undetermined which factors best predict thromboembolism in patients with PFO. Diffusion-weighted imaging (DWI) may help to distinguish the characteristics of cerebral embolism associated with different features of the interatrial septum in PFO stroke.

METHODS

In a stroke databank-based cohort study, DWI and transthoracic/transesophageal echocardiography findings were assessed in 48 consecutive patients with cryptogenic ischemic stroke associated with PFO. The number, size, and distribution of acute ischemic lesions on DWI were correlated with PFO size, degree of interatrial right-to-left shunt (RLS), and the presence of ASA.

RESULTS

Patients with PFO plus ASA combined more often had multiple acute DWI lesions (16 of 30, 53%) than those with PFO alone (3 of 18, 17%; P=0.01). This association remained significant after correction for PFO size, degree of RLS, and vascular risk factors in a logistic-regression analysis (P=0.04). No significant associations between DWI lesion characteristics and PFO size or degree of RLS were found.

CONCLUSIONS

The presence of concomitant ASA is independently associated with multiple cerebral ischemic lesions in PFO stroke, which may indicate an increased embolic risk.

Diffusion-Weighted Imaging in Acute Stroke

Diffusion MR imaging has improved evaluation of acute ischemic stroke vastly. It is highly sensitive and specific in the detection of infarction at early time points when CT and conventional MR sequences are unreliable. The initial DWI lesion is believed to represent infarction core and usually progresses to infarction unless there is early reperfusion. The initial DWI lesion volume and ADC ratios correlate highly with final infarction volume and with acute and chronic neurologic assessment tests. ADC values may be useful in differentiating tissue destined to infarct from that potentially salvageable with reperfusion therapy. ADC values also may be useful for determining tissue at risk of HT after reperfusion therapy. DTI can quantify differences in the responses of gray versus white matter to ischemia. FA may be important in determining stroke onset time, and tractography provides early detection of wallerian degeneration that may be important in determining prognosis. Finally, DWI can determine which patients who have TIA are at risk for subsequent large vessel infarction and can differentiate stroke from stroke mimics. With improvements in MR software and hardware, diffusion MR undoubtedly will continue to improve the management of patients who have acute stroke.

Distinguishing Between Stroke and Mimic at the Bedside

BACKGROUND AND PURPOSE

The bedside clinical assessment of the patient with suspected stroke has not been well studied. Improving clinical skills may accelerate patient progress through the emergency department. We aimed to determine the frequency and nature of stroke mimics and to identify the key clinical features that distinguish between stroke and mimic at the bedside.

METHODS

Consecutive presentations to an urban teaching hospital with suspected stroke were recruited. A standard bedside clinical assessment was performed. The final diagnosis was determined by an expert panel, which had access to clinical features, brain imaging, and other tests. Univariate and multivariate analyses determined the bedside features that distinguished stroke from mimic.

RESULTS

There were 350 presentations by 336 patients. The final diagnosis was stroke in 241 of 350 (69%) and mimic in 109 (31%). The mimics included 44 events labeled "possible stroke or TIA." Eight items independently predicted the diagnosis in patients presenting with brain attack: cognitive impairment and abnormal signs in other systems suggested a mimic, an exact time of onset, definite focal symptoms, abnormal vascular findings, presence of neurological signs, being able to lateralize the signs to the left or right side of the brain, and being able to determine a clinical stroke subclassification suggested a stroke.

CONCLUSIONS

The bedside clinical assessment can be streamlined substantially. This has important implications for teaching less experienced clinicians how to assess the patient with suspected stroke.

Acute small subcortical infarctions on diffusion weighted MRI: clinical presentation and aetiology

OBJECTIVE

To determine the clinical presentation and aetiology of small subcortical infarctions as found on diffusion weighted magnetic resonance imaging (DWI). DWI is both sensitive and specific in the early detection of acute ischaemic brain lesions irrespective of pre-existing vascular damage.

METHODS

Ninety three patients were identified showing subcortical or brainstem DWI lesions <1.5 cm in diameter within a maximum of 7 days from the onset of stroke symptoms. The patients' clinical status on admission was reviewed according to the Oxfordshire Community Stroke Project (OCSP). The results of procedures searching for cerebrovascular risk factors, large artery disease, and potential sources of cardiac embolism were included to determine stroke aetiology. Magnetic resonance imaging scans were also reviewed for concomitant changes that could support the aetiologic classification.

RESULTS

Only 41 (44.1%) patients presented clinically with a lacunar syndrome according to OCSP criteria. The nine (9.7%) patients who showed two or more DWI lesions in different vascular territories were also significantly more likely to have potential sources of cardiac embolism (5/9, 55.6% v 20/84, 23.8%). Hypertension was significantly more prevalent in the group of patients who showed a microangiopathy related imaging pattern, but this pattern did not exclude the presence of large artery disease or a possible cardioembolic source of stroke.

CONCLUSION

Identification of small subcortical infarctions as the cause of stroke appears quite uncertain based on clinical characteristics only. DWI adds significant aetiologic information but does not obviate the search for other potentially causative mechanisms.

Diffusion-Weighted Imaging in Acute Stroke

In magnetic resonance diffusion-weighted imaging (DWI), regions of the brain are depicted not only on the basis of physical properties, such as T2 relaxation and spin density, which influence image contrast in conventional MR imaging, but also by local characteristics of water molecule diffusion. The diffusion of water molecules is altered in a variety of disease processes, including ischemic stroke. The changes that occur in acute infarction enable DWI to detect very early ischemia. Also, because predictable progression of diffusion findings occurs during the evolution of ischemia, DWI enables more precise estimation of the time of stroke onset than does conventional imaging.