von Willebrand Factor Antigen, von Willebrand Factor Propeptide, and ADAMTS13 in Carotid Stenosis and Their Relationship with Cerebral Microemboli.

BACKGROUND: The relationship between von Willebrand factor antigen (VWF:Ag), VWF propeptide (VWFpp), VWFpp/VWF:Ag ratio, ADAMTS13 activity, and microembolic signal (MES) status in carotid stenosis is unknown. METHODS: This prospective, multicenter study simultaneously assessed plasma VWF:Ag levels, VWFpp levels and ADAMTS13 activity, and their relationship with MES in asymptomatic versus symptomatic moderate-to-severe (≥50-99%) carotid stenosis patients. One-hour transcranial Doppler ultrasound of the middle cerebral arteries classified patients as MES+ve or MES-ve. RESULTS: Data from 34 asymptomatic patients were compared with 43 symptomatic patients in the "early phase" (≤4 weeks) and 37 patients in the "late phase" (≥3 months) after transient ischemic attack (TIA)/ischemic stroke. VWF:Ag levels were higher (p = 0.049) and VWFpp/VWF:Ag ratios lower (p = 0.006) in early symptomatic than in asymptomatic patients overall, and in early symptomatic versus asymptomatic MES-ve subgroups (p ≤0.02). There were no intergroup differences in VWFpp expression or ADAMTS13 activity (p ≥0.05). VWF:Ag levels and ADAMTS13 activity decreased (p ≤ 0.048) and VWFpp/VWF:Ag ratios increased (p = 0.03) in symptomatic patients followed up from the early to late phases after TIA/stroke. Although there were no differences in the proportions of symptomatic and asymptomatic patients with blood group O, a combined analysis of early symptomatic and asymptomatic patients revealed lower median VWF:Ag levels in patients with blood group O versus those without blood group O (9.59 vs. 12.32 µg/mL, p = 0.035). DISCUSSION: VWF:Ag expression, a marker of endothelial ± platelet activation, is enhanced in recently symptomatic versus asymptomatic carotid stenosis patients, including in MES-ve patients, and decreases with ADAMTS13 activity over time following atherosclerotic TIA/ischemic stroke.

The emerging spectrum of COVID-19 neurology: clinical, radiological and laboratory findings.

Preliminary clinical data indicate that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is associated with neurological and neuropsychiatric illness. Responding to this, a weekly virtual coronavirus disease 19 (COVID-19) neurology multi-disciplinary meeting was established at the National Hospital, Queen Square, in early March 2020 in order to discuss and begin to understand neurological presentations in patients with suspected COVID-19-related neurological disorders. Detailed clinical and paraclinical data were collected from cases where the diagnosis of COVID-19 was confirmed through RNA PCR, or where the diagnosis was probable/possible according to World Health Organization criteria. Of 43 patients, 29 were SARS-CoV-2 PCR positive and definite, eight probable and six possible. Five major categories emerged: (i) encephalopathies (n = 10) with delirium/psychosis and no distinct MRI or CSF abnormalities, and with 9/10 making a full or partial recovery with supportive care only; (ii) inflammatory CNS syndromes (n = 12) including encephalitis (n = 2, para- or post-infectious), acute disseminated encephalomyelitis (n = 9), with haemorrhage in five, necrosis in one, and myelitis in two, and isolated myelitis (n = 1). Of these, 10 were treated with corticosteroids, and three of these patients also received intravenous immunoglobulin; one made a full recovery, 10 of 12 made a partial recovery, and one patient died; (iii) ischaemic strokes (n = 8) associated with a pro-thrombotic state (four with pulmonary thromboembolism), one of whom died; (iv) peripheral neurological disorders (n = 8), seven with Guillain-Barré syndrome, one with brachial plexopathy, six of eight making a partial and ongoing recovery; and (v) five patients with miscellaneous central disorders who did not fit these categories. SARS-CoV-2 infection is associated with a wide spectrum of neurological syndromes affecting the whole neuraxis, including the cerebral vasculature and, in some cases, responding to immunotherapies. The high incidence of acute disseminated encephalomyelitis, particularly with haemorrhagic change, is striking. This complication was not related to the severity of the respiratory COVID-19 disease. Early recognition, investigation and management of COVID-19-related neurological disease is challenging. Further clinical, neuroradiological, biomarker and neuropathological studies are essential to determine the underlying pathobiological mechanisms that will guide treatment. Longitudinal follow-up studies will be necessary to ascertain the long-term neurological and neuropsychological consequences of this pandemic.

Persistent psychotic symptoms following COVID-19 infection.

To date, there have been no detailed reports of patients developing persistent psychotic symptoms following Coronavirus disease 2019 (COVID-19) infection. There have been reports of patients developing transient delirium (with and without hypoxia) after COVID-19 infection as well as other neurological manifestations. We report on a female patient who, post-COVID-19 infection, developed an initial delirium followed by persistent and florid psychotic symptoms consisting of persecutory delusion, complex visual and auditory hallucinations and Capgras phenomenon in the absence of hypoxia but elevated tumour necrosis factor (TNF)-α. The psychotic symptoms persisted for about 40 days. Her magnetic resonance imaging brain scan, electroencephalogram, cerebrospinal fluid examination and extensive autoimmune panel did not show any abnormalities. The cause of the psychotic symptoms in this patient were not ascertained but we propose either an inflammatory state, characterised by the patient's elevated TNF-alpha levels as a possible contributing mechanism for her psychosis in line with the proinflammatory changes observed in some cases of psychosis. Or, an alternative, but unproven, hypothesis is one of an antibody-mediated encephalitic event induced by viral infection.

Platelet function/reactivity testing and prediction of risk of recurrent vascular events and outcomes after TIA or ischaemic stroke: systematic review and meta-analysis.

BACKGROUND: The prevalence of ex vivo 'high on-treatment platelet reactivity (HTPR)' and its relationship with recurrent vascular events/outcomes in patients with ischaemic cerebrovascular disease (CVD) is unclear. METHODS: A systematic review and meta-analysis was performed in accordance with the PRISMA statement. MEDLINE, EMBASE and Cochrane Library were searched for completed manuscripts until May 2019 on TIA/ischaemic stroke patients, ≥ 18 years, treated with commonly-prescribed antiplatelet therapy, who had platelet function/reactivity testing and prospective follow-up data on recurrent stroke/TIA, myocardial infarction, vascular death or other cerebrovascular outcomes. Data were pooled using random-effects meta-analysis. Primary outcome was the composite risk of recurrent stroke/TIA, myocardial infarction or vascular death. Secondary outcomes were recurrent stroke/TIA, severe stroke (NIHSS > 16) or disability/impairment (modified Rankin scale ≥ 3) during follow-up. RESULTS: Antiplatelet-HTPR prevalence was 3-65% with aspirin, 8-56% with clopidogrel and 1.8-35% with aspirin-clopidogrel therapy. Twenty studies (4989 patients) were included in our meta-analysis. There was a higher risk of the composite primary outcome (OR 2.93, 95% CI 1.90-4.51) and recurrent ischaemic stroke/TIA (OR 2.43, 95% CI 1.51-3.91) in patients with vs. those without 'antiplatelet-HTPR' on any antiplatelet regimen. These risks were also more than twofold higher in patients with vs. those without 'aspirin-HTPR' and 'dual antiplatelet-HTPR', respectively. Clopidogrel-HTPR status did not significantly predict outcomes, but the number of eligible studies was small. The risk of severe stroke was higher in those with vs. without antiplatelet-HTPR (OR 2.65, 95% CI 1.00-7.01). DISCUSSION: Antiplatelet-HTPR may predict risks of recurrent vascular events/outcomes in CVD patients. Given the heterogeneity between studies, further prospective, multi-centre studies are warranted.

Out of sight: a lesson in drug errors.

A 76-year-old man developed recurrent encephalopathy, visual disturbance, myoclonus, generalised seizures and atonic drop attacks on a background of a gastrectomy for adenocarcinoma and stable chronic lymphocytic leukaemia. He presented to three different hospitals and was admitted twice, with normal investigations. His symptoms transiently improved during each admission (and with starting levetiracetam) but recurred each time on hospital discharge. Subsequent careful inspection of his medication box identified that his community pharmacy had in error been dispensing baclofen 80 mg per day instead of his prescribed Buscopan 80 mg per day. This case highlights the importance of physically inspecting a patient's medications and emphasises the spectrum of baclofen-related toxicity; it also highlights potential deficiencies in the pharmacy dispensary process and the need for multiple checks by patients and professionals.

Increased Leucocyte-Platelet Complex Formation in Recently Symptomatic versus Asymptomatic Carotid Stenosis Patients and in Micro-emboli Negative Subgroups.

INTRODUCTION: Cerebral micro-embolic signals (MES) predict risk of stroke in carotid stenosis patients. However, MES-negative 'recently symptomatic patients' also have a higher stroke risk than 'asymptomatic patients'. Differences in platelet activation status may contribute to this disparity in risk. METHODS: This prospective, observational study assessed platelet biomarkers and their relationship with MES in asymptomatic versus symptomatic moderate (≥50-69%) or severe (≥70-99%) carotid stenosis patients. Full blood count parameters were measured and whole-blood flow cytometry was used to quantify platelet surface CD62P and CD63 expression and leucocyte-platelet complex formation. Bilateral simultaneous transcranial Doppler ultrasound of the middle cerebral arteries classified patients as 'MES positive' or 'MES negative'. RESULTS: Data from 34 asymptomatic patients were compared with those from 43 symptomatic patients in the 'early phase' (≤ 4 weeks) and 37 of these symptomatic patients in the 'late phase' (≥ 3 months) after transient ischaemic attack/ischaemic stroke. There were no differences in %CD62P or %CD63 expression between early or late symptomatic and asymptomatic patients overall (p > 0.05). The percentage of lymphocyte-platelet complexes was higher in early symptomatic than in asymptomatic patients (2.8 vs. 2.16%; p < 0.001). MES were more commonly observed in early symptomatic (31.4%; p = 0.027) but not in late symptomatic (6.7%; p = 0.996) versus asymptomatic patients (7.1%). The percentage of lymphocyte-platelet complexes was higher in early symptomatic than in asymptomatic MES-negative patients (2.7 vs. 2.17%; p = 0.02). CONCLUSION: These data add to the evidence that leucocyte-platelet complex formation/platelet activation is increased in recently symptomatic versus asymptomatic patients, and may contribute to the pathogenesis of first and subsequent strokes in carotid stenosis patients, including those who are MES negative.

Clinical outcomes and a high prevalence of abnormalities on comprehensive arterial and venous thrombophilia screening in TIA or ischaemic stroke patients with a patent foramen ovale, an inter-atrial septal aneurysm or both.

INTRODUCTION: Data are limited on the optimal management of cryptogenic TIA/stroke patients with a patent foramen ovale (PFO)±inter-atrial septal aneurysm (IASA), especially with an inherited thrombophilia. METHODS: Prospectively-collected data on TIA/ischaemic stroke patients with PFO, IASA or both who received 'goal-directed secondary-prevention medical treatment' were analysed. All patients had trans-oesophageal echocardiography, anti-nuclear, anti-cardiolipin, anti-beta 2 glycoprotein I antibodies, rheumatoid factor, lupus anticoagulant, protein C&S, anti-thrombin, factor VIII activity, activated protein C resistance, Factor V Leiden, prothrombin gene and MTHFR-c.677C>T mutation screening. ENA and homocysteine were assessed in the latter study period. RESULTS: Eighty-three patients were recruited. Mean follow-up: 48.1months. Forty-seven patients (56.6%) had an isolated PFO, 32 (38.6%) a PFO and an IASA, and 4 (4.8%) an IASA alone. Eighteen (21.7%) had ≥1 abnormality on thrombophilia screening. The most important abnormalities which lead to treatment changes in 11 patients (13.3%) were primary anti-phospholipid syndrome (N=3; 3.6%), protein S deficiency (N=2; 2.4%) hyper-homocysteinaemia (N=6/72 screened, 8.3%). Four patients (4.8%) opted for PFO closure: two with protein S deficiency, and two with no identified thrombophilia. Seven (8.4%) had recurrent TIA/ischaemic stroke during follow-up (overall annualised incidence: 2.1%), of whom five had a PFO alone and two a PFO and IASA. DISCUSSION: Comprehensive arterial and venous thrombophilia screening is warranted in TIA/ischaemic stroke patients with a PFO±IASA, is conclusively abnormal in over a fifth, and informed important decision-making regarding individualised therapy in 13.3% of patients. The incidence of recurrent vascular events in this population is low on optimal, personalised secondary-prevention treatment, even with an underlying thrombophilia.

Platelet function testing in transient ischaemic attack and ischaemic stroke: A comprehensive systematic review of the literature.

The majority of patients with ischaemic cerebrovascular disease (CVD) are not protected from further vascular events with antiplatelet therapy. Measurement of inhibition of platelet function ex vivo on antiplatelet therapy, using laboratory tests that correlate with the clinical effectiveness of these agents, would potentially enable physicians to tailor antiplatelet therapy to suit individuals. A systematic review of the literature was performed to collate all available data on ex vivo platelet function/reactivity in CVD patients, especially those treated with aspirin, dipyridamole or clopidogrel. Particular emphasis was paid to information from commonly available whole blood platelet function analysers (PFA-100®, VerifyNow® and Multiplate®). Data on pharmacogenetic mechanisms potentially influencing high on-treatment platelet reactivity (HTPR) on antiplatelet therapy in CVD were reviewed. Two-hundred forty-nine potentially relevant articles were identified; 93 manuscripts met criteria for inclusion. The prevalence of ex vivo HTPR in CVD varies between 3-62% with aspirin monotherapy, 8-61% with clopidogrel monotherapy and 56-59% when dipyridamole is added to aspirin in the early, subacute or late phases after TIA/stroke onset. The prevalence of HTPR on aspirin was higher on the PFA-100 than on the VerifyNow in one study (p < 0.001). Furthermore, the prevalence of HTPR on aspirin was lower when one used 'novel longitudinal' rather than 'cross-sectional, case-control' definitions of HTPR on the PFA early after TIA or stroke (p = 0.003; 1 study). Studies assessing the influence of genetic polymorphisms on HTPR in CVD patients are limited, and need validation in large multicentre studies. Available data illustrate that an important proportion of CVD patients have ex vivo HTPR on their prescribed antiplatelet regimen, and that the prevalence varies depending on the definition and assay used. Large, adequately-sized, prospective multicentre collaborative studies are urgently needed to determine whether comprehensive assessment of HTPR at high and low shear stress with a range of user-friendly whole blood platelet function testing platforms, in conjunction with pharmacogenetic data, improves our ability to predict the risk of recurrent vascular events in CVD patients, and thus enhance secondary prevention following TIA or ischaemic stroke.