Risk, Clinical Course, and Outcome of Ischemic Stroke in Patients Hospitalized With COVID-19: A Multicenter Cohort Study.

BACKGROUND AND PURPOSE: The frequency of ischemic stroke in patients with coronavirus disease 2019 (COVID-19) varies in the current literature, and risk factors are unknown. We assessed the incidence, risk factors, and outcomes of acute ischemic stroke in hospitalized patients with COVID-19. METHODS: We included patients with a laboratory-confirmed SARS-CoV-2 (severe acute respiratory syndrome coronavirus-2) infection admitted in 16 Dutch hospitals participating in the international CAPACITY-COVID registry between March 1 and August 1, 2020. Patients were screened for the occurrence of acute ischemic stroke. We calculated the cumulative incidence of ischemic stroke and compared risk factors, cardiovascular complications, and in-hospital mortality in patients with and without ischemic stroke. RESULTS: We included 2147 patients with COVID-19, of whom 586 (27.3%) needed treatment at an intensive care unit. Thirty-eight patients (1.8%) had an ischemic stroke. Patients with stroke were older but did not differ in sex or cardiovascular risk factors. Median time between the onset of COVID-19 symptoms and diagnosis of stroke was 2 weeks. The incidence of ischemic stroke was higher among patients who were treated at an intensive care unit (16/586; 2.7% versus nonintensive care unit, 22/1561; 1.4%; P=0.039). Pulmonary embolism was more common in patients with (8/38; 21.1%) than in those without stroke (160/2109; 7.6%; adjusted risk ratio, 2.08 [95% CI, 1.52-2.84]). Twenty-seven patients with ischemic stroke (71.1%) died during admission or were functionally dependent at discharge. Patients with ischemic stroke were at a higher risk of in-hospital mortality (adjusted risk ratio, 1.56 [95% CI, 1.13-2.15]) than patients without stroke. CONCLUSIONS: In this multicenter cohort study, the cumulative incidence of acute ischemic stroke in hospitalized patients with COVID-19 was ≈2%, with a higher risk in patients treated at an intensive care unit. The majority of stroke patients had a poor outcome. The association between ischemic stroke and pulmonary embolism warrants further investigation.

A prospective open-label study of sirolimus for the treatment of anti-Hu associated paraneoplastic neurological syndromes.

BACKGROUND: Several lines of evidence suggest a T cell-mediated immune response in paraneoplastic neurological syndromes with anti-Hu antibodies (Hu-PNS). In order to investigate whether suppression of T cell-mediated immune responses in Hu-PNS patients improved their neurological outcome, we performed a prospective open-label, single-arm study on sirolimus. METHODS: Seventeen progressive Hu-PNS patients were treated with sirolimus with an intended treatment duration of 8 weeks. Primary outcome measures were (i) functional improvement, defined as a decrease of one or more points on the modified Rankin Scale (mRS), and (ii) improvement of neurological impairment, defined as an increase of one or more points on the Edinburgh Functional Impairment Tests (EFIT). RESULTS: One patient showed improvement on both clinical scales (mRS and EFIT). This patient presented with limbic encephalitis and improved dramatically from an mRS score of 3 to mRS 1. Another patient, with subacute sensory neuronopathy, remained stable at mRS 2 and improved one point on the EFIT scale. The other patients showed no improvement on the primary outcome measures. Median survival was 21 months. CONCLUSION: We conclude that treatment of Hu-PNS patients with sirolimus may improve or stabilize their functional disabilities and neurological impairments. However, the effects of this T cell-targeted therapy were not better than reported in trials on other immunotherapies for Hu-PNS. Trial Registration https://www.clinicaltrialsregister.eu/ctr-search/trial/2008-000793-20/NL.

Clinical reasoning: a 76-year-old man remaining comatose after cardiopulmonary resuscitation.

A 76-year-old man was admitted to the hospital after having a "cardiac arrest" while riding his bicycle and subsequently falling into a canal. Thirty minutes after the accident, he was resuscitated by an ambulance crew. They detected a ventricular tachycardia, which responded to defibrillation. Thereafter, there was a sinus bradycardia, which was treated with atropine and adrenaline. After 30 minutes of resuscitation, there was return of spontaneous circulation (ROSC). At admission to our hospital, the patient was comatose, with a body temperature of 30°C and Glasgow Coma Scale score (GCS) of E1M1V1. According to protocol for presumed acute hypoxic ischemic encephalopathy, he was started on therapeutic hypothermia. The body temperature of the patient was kept at 32°C to 34°C for 24 hours. A few hours after starting hypothermia, twitches around the eyes and mouth were noticed and a neurology consultation was requested. Neurologic examination during hypothermia and under sedation showed a deeply comatose patient with intact pupillary reaction to light bilaterally and present oculocephalic reflex. He had multifocal random twitching movements involving the face, arms, and legs. These shock-like movements were found to increase by external stimuli.

Elevated numbers of regulatory T cells, central memory T cells and class-switched B cells in cerebrospinal fluid of patients with anti-Hu antibody associated paraneoplastic neurological syndromes.

Multi-parametric flow cytometry was used to study lymphocyte subsets and dendritic cells in paired blood and CSF samples from 11 newly diagnosed patients with progressive anti-Hu antibody associated paraneoplastic neurological syndromes (Hu-PNS), 9 patients with other inflammatory neurologic disorders (IND), and 12 patients with other non-inflammatory neurologic disorders (OND). Hu-PNS patients had elevated numbers of regulatory T cells, central memory T cells, class-switched B cells and dendritic cells in their CSF. These findings support the hypothesis that the immune system is locally activated in Hu-PNS, and suggests common etiological pathways between Hu-PNS and other inflammatory central nervous system disorders.

Effector memory and late memory T cells accumulate in the blood of CMV-carrying individuals but not in their cerebrospinal fluid.

Cytomegalovirus (CMV)-carrying individuals have significantly higher levels of effector memory and late memory T lymphocytes in their blood than non-carriers. To date, it is well recognized that the central nervous system is subjected to active immunosurveillance, as evidenced by the presence of central memory T cells in cerebrospinal fluid (CSF) of healthy individuals. In order to investigate whether levels of effector memory and late memory T cells were also increased in the CSF of CMV-carrying individuals, we characterized CD4⁺ and CD8⁺ T-cell subsets in CSF and blood of both groups. Effector memory and late memory T cells were only rarely seen in CSF, which was similar in CMV carriers and non-carriers. In conclusion, there was no demonstrable difference in the numbers of CSF effector memory and late memory T cells between CMV seronegative and CMV seropositive individuals.

Three sensitive assays do not provide evidence for circulating HuD-specific T cells in the blood of patients with paraneoplastic neurological syndromes with anti-Hu antibodies.

Anti-Hu antibody-associated paraneoplastic neurological syndromes (Hu-PNSs) are severe and often precede the detection of a malignancy, usually small-cell lung cancer. In Hu-PNS, it is hypothesized that neuronal cells are destroyed by T cells targeted against HuD, a protein expressed by small-cell lung cancer cells and neurons. There is only limited evidence for the existence of HuD-specific T cells. To detect these T cells in the blood of Hu-PNS patients, we employed 3 highly sensitive assays that included T cell stimulation with dendritic cells (DCs) to specifically expand the number of any HuD-specific T cells. A total of 17 Hu-PNS patients were tested with 1 or more of the following 3 assays: (1) tetramer staining after stimulation of T cells with conventionally generated DCs (n = 9), (2) interleukin (IL)-13 enzyme-linked immunosorbent spot (ELISpot; n = 3), IL-4 and IL-5 and interferon (IFN)-γ multiplex cytokine bead array (n = 2) to assay cytokine production by T cells after stimulation with conventionally generated DCs, and (iii) IFN-γ ELISpot and tetramer staining after T cell stimulation with accelerated co-cultured DCs (n = 11). No circulating HuD-specific T cells were found. We suggest that either autoaggressive T cells in Hu-PNS are not targeted against HuD or that their numbers in the blood are too low for detection by highly sensitive techniques.

Flow cytometric characterization of cerebrospinal fluid cells.

Flow cytometry facilitates the detection of a large spectrum of cellular characteristics on a per cell basis, determination of absolute cell numbers and detection of rare events with high sensitivity and specificity. White blood cell (WBC) counts in cerebrospinal fluid (CSF) are important for the diagnosis of many neurological disorders. WBC counting and differential can be performed by microscopy, hematology analyzers, or flow cytometry. Flow cytometry of CSF is increasingly being considered as the method of choice in patients suspected of leptomeningeal localization of hematological malignancies. Additionally, in several neuroinflammatory diseases such as multiple sclerosis and paraneoplastic neurological syndromes, flow cytometry is commonly performed to obtain insight into the immunopathogenesis of these diseases. Technically, the low cellularity of CSF samples, combined with the rapidly declining WBC viability, makes CSF flow cytometry challenging. Comparison of flow cytometry with microscopic and molecular techniques shows that each technique has its own advantages and is ideally combined. We expect that increasing the number of flow cytometric parameters that can be simultaneously studied within one sample, will further refine the information on CSF cell subsets in low-cellular CSF samples and enable to define cell populations more accurately.

Addition of serum-containing medium to cerebrospinal fluid prevents cellular loss over time.

Immediately after sampling, leukocyte counts in native cerebrospinal fluid (CSF) start to decrease rapidly. As the time lapse between CSF collection to analysis is not routinely registered, the clinical significance of decreasing cell counts in native CSF is not known. Earlier data suggest that addition of serum-containing medium to CSF directly after sampling prevents this rapid decrease in leukocyte counts and, thus, may improve the accuracy of CSF cell counting and cell characterization. Here, we prospectively examined the effect of storage time after lumbar puncture on counts of leukocytes and their major subsets in both native CSF and after immediate addition of serum-containing medium, measured by flow cytometry and microscopy. We collected CSF samples of 69 patients in tubes with and tubes without serum-containing medium and determined counts of leukocytes and subsets at 30 minutes, 1 hour, and 5 hours after sampling. Compared to cell counts at 30 minutes, no significant decrease in cell number was observed in CSF with serum-containing medium 1 and 5 hours after sampling, except for the granulocytes at 1 hour. In native CSF, approximately 50% of leukocytes and all their subsets were lost after 1 hour, both in flow cytometric and microscopic counting. In 6/7 (86%) samples with mild pleocytosis (5-15 × 10(6) leukocytes/l), native CSF at 1 hour was incorrectly diagnosed as normocellular. In conclusion, addition of serum-containing medium to CSF directly after sampling prevents cell loss and allows longer preservation of CSF cells prior to analysis, both for microscopic and flow cytometric enumeration. We suggest that this protocol results in more accurate CSF cell counts and may prevent incorrect conclusions based on underestimated CSF cell counts.

Central memory CD4+ T cells dominate the normal cerebrospinal fluid.

BACKGROUND: To use cerebrospinal fluid (CSF) immune phenotyping as a diagnostic and research tool, we have set out to establish reference values of white blood cell (WBC) subsets in CSF. METHODS: We assessed the absolute numbers and percentages of WBC subsets by 6-color flow cytometry in paired CSF and blood samples of 84 individuals without neurological disease who underwent spinal anaesthesia for surgery. Leukocyte (i.e., lymphocytes, granulocytes, and monocytes), lymphocyte (i.e., T [CD4(+) and CD8(+) ], NK, NKT and B cells), T cell (i.e., naïve, central memory, effector memory, and regulatory) and dendritic cell subsets (i.e., myeloid and plasmacytoid) were studied. RESULTS: CSF showed a predominance of T cells, while granulocytes, B and NK cells were relatively rare compared to blood. The majority of T cells in CSF consisted of CD4(+) T cells (∼70%), most of them (∼90%) with a central memory phenotype, while B cells were almost absent (<1%). Among the small population of dendritic cells in CSF, those of the myeloid subtype were more frequent than plasmacytoid dendritic cells (medians: 1.7% and 0.4% of leukocytes, respectively), whilst both subsets made up 0.2% of leukocytes in blood. CONCLUSIONS: This study reports reference values of absolute numbers and percentages of WBC subsets in CSF, which are essential for further investigation of the immunopathogenesis of neuro-inflammatory diseases. Furthermore, the relative abundance of CD4(+) T cells, mainly with a central memory phenotype, and the presence of dendritic cells in CSF suggests an active adaptive immune response under normal conditions in the central nervous system (CNS).

HLA-DQ2+ individuals are susceptible to Hu-Ab associated paraneoplastic neurological syndromes.

BACKGROUND: Hypothetically, T cells are involved in the pathogenesis of paraneoplastic neurological syndromes associated with Hu-antibodies (Hu-PNS). OBJECTIVE: To identify genetic risk factors for Hu-PNS and investigate the role of T cells. METHODS: HLA-A, B, DRB1 and DQB1 alleles were compared in 53 Hu-PNS patients with 24 small-cell lung-cancer (SCLC) patients and 2440 healthy controls (HC). RESULTS: The frequency of both HLA-DQ2 and HLA-DR3 was significantly higher in Hu-PNS patients than in HC. CONCLUSIONS: This study indicates an association between Hu-PNS and presence of HLA-DQ2 and HLA-DR3, which supports a role for CD4(+) T cells in the pathogenesis of Hu-PNS.

Evaluation of the new body fluid mode on the Sysmex XE-5000 for counting leukocytes and erythrocytes in cerebrospinal fluid and other body fluids.

BACKGROUND: We evaluated the body fluid (BF) mode on the new Sysmex XE-5000 analyzer. METHODS: Red (RBC) and white blood cell (WBC) (differential) counts of BFs (139 patient samples and 87 normal samples) were measured and compared to the Fuchs-Rosenthal chamber and stained cytospin slides. RESULTS: Extended cell counting using the BF mode was noted to have an improved WBC detection limit (CV(20)%) of 10 x 10(6)/L. Excellent agreement with the manual method was observed for most BFs [mean bias +2 to 6 x 10(6)/L for cerebrospinal fluid (CSF) and -1 to 12 x 10(6)/L for other fluids]. In CSF, the BF-mode counted more WBC (polymorphic nuclear cells) compared with the manual method (mean bias +5 to 6 x 10(6)/L), especially in samples with low cell counts (<20 x 10(6)/L). Carry over was negligible (mostly <0.17%) and linearity was excellent (mean bias <5%). The reference ranges for CSF (n=87) were RBC 0 x 10(6)/L, WBC and mononuclear <7 x 10(6)/L, and polymorph nucleated cells <3 x 10(6)/L. CONCLUSIONS: The BF mode on the Sysmex XE-5000 offers rapid and accurate RBC and WBC (differential) counts in clinically relevant concentration ranges in CSF and other fluids. In addition, the exclusion of high fluorescent cells, such as mesothelial cells and macrophages from WBC counting may reduce the number of manual analyses in pleural fluids and ascites.

Contamination of synthetic HuD protein spanning peptide pools with a CMV-encoded peptide.

To detect HuD-specific T cells in patients with Hu-antibody associated paraneoplastic neurological syndromes (Hu-PNS), we used short-term stimulation assays with HuD protein spanning peptide pools (PSPP) with purities of at least 70% and found reproducible false-positive CD8+ T-cell responses in three of 127 individuals (two healthy controls and one Hu-PNS patient), which all shared HLA-A*2402 and HLA-B*1801. After testing the 15-mer peptides of the HuD antigen separately, we discovered that the same three 15-mers yielded the CD8+ T cell response in those three individuals. This highly unusual result could not be reproduced when using new batches of peptides with a higher level of purity (>82% and >95%). Therefore, we assumed this response was not directed against the HuD peptides and analyzed the HuD 15-mers by Fourier transform ion cyclotron resonance (FT-ICR) tandem mass spectrometry (MS/MS), which showed the presence of a cytomegalovirus (CMV)-encoded peptide (AIAEESDEEEAIVAY) as a contaminant. The three responding individuals all were CMV-seropositive and the contaminating peptide appeared to fit in the binding groove of HLA-B*18. Our data reveal that synthetic PSPP may contain immunogenic contaminations which may cause false positive results in T-cell stimulation assays.

Vestibulospinal component of postural control (vestibular function) in very preterm infants (25 to 27 weeks) at 3, 6, and 12 months corrected age.

Postural control, which is important for the development of all movement, balance, and locomotion, depends a great deal on the vestibulospinal component of vestibular function in early childhood. Vestibulospinal input is important for muscle power regulation, which, in turn, influences postural control. The aim of this study was to focus particularly on this component of vestibular function during the first year of life in 67 infants with a very short gestational age (25-27 weeks), to search for possible neonatal confounders, and to see whether it influences the course of muscle power development in preterm infants. Outcome was described as being optimal, suspect, or abnormal. The infants were categorized into the Neonatal Medical Index according to the severity of neonatal illness and separately into three groups for neonatal brain ultrasonography findings (normal to severe abnormalities). At the age of 3 months, 20 infants performed optimally on all items testing vestibular function, increasing to 40 at 6 months and 48 at 12 months. This significant improvement (also seen in muscle power regulation) was primarily caused by better head control (during the traction response and prone position), whereas less shoulder retraction and hyperextension were found in the sitting position. Vestibular function was significantly related to brain ultrasonography classification but not to gestational age, birthweight, the Neonatal Medical Index, or gender.