The use of transcranial ultrasound and clinical assessment to diagnose ischaemic stroke due to large vessel occlusion in remote and rural areas

Abstract

Rapid endovascular thrombectomy, which can only be delivered in specialist centres, is the most effective treatment for acute ischaemic stroke due to large vessel occlusion (LVO). Pre-hospital selection of these patients is challenging, especially in remote and rural areas due to long transport times and limited access to specialist clinicians and diagnostic facilities. We investigated whether combined transcranial ultrasound and clinical assessment ("TUCA" model) could accurately triage these patients and improve access to thrombectomy. We recruited consecutive patients within 72 hours of suspected stroke, and performed non-contrast transcranial colour-coded ultrasonography within 24 hours of brain computed tomography. We retrospectively collected clinical information, and used hospital discharge diagnosis as the "gold standard". We used binary regression for diagnosis of haemorrhagic stroke, and an ordinal regression model for acute ischaemic stroke with probable LVO, without LVO, transient ischaemic attacks (TIA) and stroke mimics. We calculated sensitivity, specificity, positive and negative predictive values and performed a sensitivity analysis. We recruited 107 patients with suspected stroke from July 2017 to December 2019 at two study sites: 13/107 (12%) with probable LVO, 50/107 (47%) with acute ischaemic stroke without LVO, 18/107 (17%) with haemorrhagic stroke, and 26/107 (24%) with stroke mimics or TIA. The model identified 55% of cases with probable LVO who would have correctly been selected for thrombectomy and 97% of cases who would not have required this treatment (sensitivity 55%, specificity 97%, positive and negative predictive values 75% and 93%, respectively). Diagnostic accuracy of the proposed model was superior to the clinical assessment alone. These data suggest that our model might be a useful tool to identify prehospital patients requiring mechanical thrombectomy, however a larger sample is required with the use of CT angiogram as a reference test.

Evidence of woven bone formation in carotid artery plaques

“…Histological studies of coronary atherosclerosis suggest that plaques can be identi ied by thin ibrous caps that overlie large, often necrotic lipid cores [11,12]. A multimodal assessment of plaque vulnerability involving the combination of systemic markers, new imaging methods, for example, ultrasonic investigation, ct-imaging and MRI that target in lammatory and thrombotic components, and the potential of emerging therapies may lead to a new strati ication system for atherothrombotic risk and to a better prevention of atherothrombotic stroke [3][4][5][13][14][15][16]. Mechanisms of plaque rupture have been extensively studied and several parameters have been found to interact: extracellular matrix, in lammatory cells, gelatinases, stromelysins, matrilysin and MMp expression induced by oxidised lipids etc.…”

National implementation of reperfusion for acute ischaemic stroke in England: How should services be configured? A modelling study

“… 45 Though RACE improves selection of LAO patients, we found applying RACE still has the potential to destabilise the current organisation of care through its low specificity; furthermore the latest trial data suggest that the widespread use of such pre-hospital selection does not confer the anticipated benefits in terms of improved outcomes from bypass and earlier treatment with MT. 40 More sophisticated pre-hospital pathways, such as supporting paramedics with centralised triage 33 or advances in technology, such as use of biomarkers 46 or ultrasound devices 47 for detecting LAO, may be necessary to achieve the requisite balance of sensitivity and specificity. Selection of patients eligible for MT will always selectively divert patients who are more likely to also receive IVT.…”

Emerging Detection Techniques for Large Vessel Occlusion Stroke: A Scoping Review

“…Fifteen imaging and physiological monitoring methods were identified, of which 5 were advancements in computed tomography angiography (CTA) (41-45) and 2 used MRI methods (46,47). The remaining records explored different modalities, including standard CT (48), a triage model combining transcranial ultrasound with clinical assessment (49), cranial accelerometery (50), volumetric impedance phase shift spectroscopy (VIPS) (51), and intraoperative neurological monitoring (IONM) (52). The final 3 studies observed cerebral blood flow velocity (CBFV) waveforms using transcranial Doppler ultrasound (TCD) (53)(54)(55).…”

“…The effectiveness of a triage model combining transcranial ultrasound and clinical assessment was assessed to help select patients for intravenous thrombolysis or MT (49). This approach had excellent specificity (97%) but lacked the ability to identify 55% of patients with potential LVOs (49).…”

“…Direct comparison between studies in this scoping review proved difficult due to the different gold standards used for delineating "true LVO", suggesting heterogeneity between studies. Studies including Purrucker et al (17) and Antipova et al (49) referred to the patient's hospital discharge diagnosis as the "gold standard" (17,49). However, some stroke scale studies, such as Noorian et al (10), Lawner et al (16), and Brandler et al (12), noted the NIHSS as the "gold standard" stroke scale for LVO stroke severity assessment and diagnosis.…”