Laboratory diagnosis of CNS infections in children due to emerging and re-emerging neurotropic viruses.

Recent decades have witnessed the emergence and re-emergence of numerous medically important viruses that cause central nervous system (CNS) infections in children, e.g., Zika, West Nile, and enterovirus/parechovirus. Children with immature immune defenses and blood-brain barrier are more vulnerable to viral CNS infections and meningitis than adults. Viral invasion into the CNS causes meningitis, encephalitis, brain imaging abnormalities, and long-term neurodevelopmental sequelae. Rapid and accurate detection of neurotropic viral infections is essential for diagnosing CNS diseases and setting up an appropriate patient management plan. The addition of new molecular assays and next-generation sequencing has broadened diagnostic capabilities for identifying infectious meningitis/encephalitis. However, the expansion of test menu has led to new challenges in selecting appropriate tests and making accurate interpretation of test results. There are unmet gaps in development of rapid, sensitive and specific molecular assays for a growing list of emerging and re-emerging neurotropic viruses. Herein we will discuss the advances and challenges in the laboratory diagnosis of viral CNS infections in children. This review not only sheds light on selection and interpretation of a suitable diagnostic test for emerging/re-emerging neurotropic viruses, but also calls for more research on development and clinical utility study of novel molecular assays. IMPACT: Children with immature immune defenses and blood-brain barrier, especially neonates and infants, are more vulnerable to viral central nervous system infections and meningitis than adults. The addition of new molecular assays and next-generation sequencing has broadened diagnostic capabilities for identifying infectious meningitis and encephalitis. There are unmet gaps in the development of rapid, sensitive and specific molecular assays for a growing list of emerging and re-emerging neurotropic viruses.

Elevated phospholipids and acylcarnitines C4 and C5 in cerebrospinal fluid distinguish viral CNS infections from autoimmune neuroinflammation.

BACKGROUND: Viral and autoimmune encephalitis may present with similar symptoms, but require different treatments. Thus, there is a need for biomarkers to improve diagnosis and understanding of pathogenesis. We hypothesized that virus-host cell interactions lead to different changes in central nervous system (CNS) metabolism than autoimmune processes and searched for metabolite biomarkers in cerebrospinal fluid (CSF) to distinguish between the two conditions. METHODS: We applied a targeted metabolomic/lipidomic analysis to CSF samples from patients with viral CNS infections (n = 34; due to herpes simplex virus [n = 9], varicella zoster virus [n = 15], enteroviruses [n = 10]), autoimmune neuroinflammation (n = 25; autoimmune anti-NMDA-receptor encephalitis [n = 8], multiple sclerosis [n = 17), and non-inflamed controls (n = 31; Gilles de la Tourette syndrome [n = 20], Bell's palsy with normal CSF cell count [n = 11]). 85 metabolites passed quality screening and were evaluated as biomarkers. Standard diagnostic CSF parameters were assessed for comparison. RESULTS: Of the standard CSF parameters, the best biomarkers were: CSF cell count for viral infections vs. controls (area under the ROC curve, AUC = 0.93), Q-albumin for viral infections vs. autoimmune neuroinflammation (AUC = 0.86), and IgG index for autoimmune neuroinflammation vs. controls (AUC = 0.90). Concentrations of 2 metabolites differed significantly (p < 0.05) between autoimmune neuroinflammation and controls, with proline being the best biomarker (AUC = 0.77). In contrast, concentrations of 67 metabolites were significantly higher in viral infections than controls, with SM.C16.0 being the best biomarker (AUC = 0.94). Concentrations of 68 metabolites were significantly higher in viral infections than in autoimmune neuroinflammation, and the 10 most accurate metabolite biomarkers (AUC = 0.89-0.93) were substantially better than Q-albumin (AUC = 0.86). These biomarkers comprised six phosphatidylcholines (AUC = 0.89-0.92), two sphingomyelins (AUC = 0.89, 0.91), and acylcarnitines isobutyrylcarnitine (C4, AUC = 0.92) and isovalerylcarnitine (C5, AUC = 0.93). Elevated C4 and C5 concentrations suggested dysfunctional mitochondrial ß-oxidation and correlated only moderately with CSF cell count (Spearman ρ = 0.41 and 0.44), indicating that their increase is not primarily driven by inflammation. CONCLUSIONS: Changes in CNS metabolism differ substantially between viral CNS infections and autoimmune neuroinflammation and reveal CSF metabolites as pathophysiologically relevant diagnostic biomarkers for the differentiation between the two conditions. In viral CNS infections, the observed higher concentrations of free phospholipids are consistent with disruption of host cell membranes, whereas the elevated short-chain acylcarnitines likely reflect compromised mitochondrial homeostasis and energy generation.

Acute Flaccid Myelitis in a Pediatric Patient With Coronavirus Disease 2019.

The etiology of acute flaccid myelitis (AFM) has yet to be determined. Viral link has been suggested, but severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-associated AFM has not been reported in children. We describe a three-year-old boy, with AFM associated with coronavirus disease 2019 (COVID-19) infection. In the era of COVID-19 pandemic, patients with AFM should be tested for SARS-CoV-2.

Comparison of acute flaccid myelitis and transverse myelitis in children and evaluation of diagnostic criteria.

BACKGROUND AND PURPOSE: Acute flaccid myelitis (AFM) and transverse myelitis (TM) are serious conditions that may be difficult to differentiate, especially at onset of disease. In this study, we compared clinical features of pediatric AFM and TM and evaluated current diagnostic criteria, aiming to improve early and accurate diagnosis. METHODS: Two cohorts of children with enterovirus D68-associated AFM and clinically diagnosed TM were compared regarding presenting clinical features, additional investigations, and outcome. Current diagnostic criteria for AFM and TM were applied to evaluate their specificity. RESULTS: Children with AFM (n = 21) compared to those with TM (n = 36) were younger (median 3 vs. 10 years), more often had a prodromal illness (100% vs. 39%), predominant proximal weakness (69% vs. 17%), and hyporeflexia (100% vs. 44%), and less often had sensory deficits (0% vs. 81%), bowel and/or bladder dysfunction (12% vs. 69%), and hyperreflexia (0% vs. 44%). On magnetic resonance imaging, brainstem involvement was more common in AFM (74% vs. 21%), whereas supratentorial abnormalities were only seen in TM (0% vs. 40%). When omitting the criterion of a sensory level, 11 of 15 (73%) children with AFM fulfilled the diagnostic criteria for TM. Of children with TM, four of 33 (12%) fulfilled the diagnostic criteria for probable/definite AFM. CONCLUSIONS: Although there is considerable overlap between AFM and TM in children, we found important early differentiating clinical and diagnostic features. Meeting diagnostic criteria for AFM in children with TM and vice versa underlines the importance of thorough clinical examination and early and accurate diagnostic studies.

Serial Neurologic Examination in a Child With Acute Flaccid Weakness.

A 5-month-old healthy infant presented with acute flaccid weakness, anisocoria, and urinary retention with clinical suspicion of acute flaccid myelitis versus acute transverse myelitis.

Challenges in the Clinical Recognition of Acute Flaccid Myelitis and its Implications.

OBJECTIVES: To explore the challenges in diagnosing acute flaccid myelitis (AFM) and evaluate clinical features and treatment paradigms associated with under recognition. STUDY DESIGN: This was a retrospective multicenter study of pediatric patients (≤18 years) who were diagnosed with AFM from 2014 to 2018 using the Centers for Disease Control and Prevention's case definition. RESULTS: In 72% of the cases (126 of 175), AFM was not considered in the initial differential diagnosis (n = 108; 61.7%) and/or the patient was not referred for acute care (n = 90; 51.4%) at the initial clinical encounter, and this did not improve over time. Although many features of the presentation were similar in those initially diagnosed with AFM and those who were not; preceding illness, constipation, and reflexes differed significantly between the 2 groups. Patients with a non-AFM initial diagnosis more often required ventilatory support (26.2% vs 12.2%; OR, 0.4; 95% CI, 0.2-1.0; P = .05). These patients received immunomodulatory treatment later (3 days vs 2 days after neurologic symptom onset; 95% CI, -2 to 0; P = .05), particularly intravenous immunoglobulin (5 days vs 2 days; 95% CI, -4 to -2; P < .001). CONCLUSIONS: Delayed recognition of AFM is concerning because of the risk for respiratory decompensation and need for intensive care monitoring. A non-AFM initial diagnosis was associated with delayed treatment that could have a clinical impact, particularly as new treatment options emerge.

Epidemiology of acute flaccid myelitis in children in the Netherlands, 2014 to 2019.

BackgroundAcute flaccid myelitis (AFM) is a polio-like condition affecting mainly children and involving the central nervous system (CNS). AFM has been associated with different non-polio-enteroviruses (EVs), in particular EV-D68 and EV-A71. Reliable incidence rates in European countries are not available.AimTo report AFM incidence in children in the Netherlands and its occurrence relative to EV-D68 and EV-A71 detections.MethodsIn 10 Dutch hospitals, we reviewed electronic health records of patients diagnosed with a clinical syndrome including limb weakness and/or CNS infection and who were < 18 years old when symptoms started. After excluding those with a clear alternative diagnosis to AFM, those without weakness, and removing duplicate records, only patients diagnosed in January 2014-December 2019 were retained and further classified according to current diagnostic criteria. Incidence rates were based on definite and probable AFM cases. Cases' occurrences during the study period were co-examined with laboratory-surveillance detections of EV-D68 and EV-A71.ResultsAmong 143 patients included, eight were classified as definite and three as probable AFM. AFM mean incidence rate was 0.06/100,000 children/year (95% CI: -0.03 to 0.14). All patient samples were negative for EV-A71. Of respiratory samples in seven patients, five were EV-D68 positive. AFM cases clustered in periods with increased EV-D68 and EV-A71 detections.ConclusionsAFM is rare in children in the Netherlands. The temporal coincidence of EV-D68 circulation and AFM and the detection of this virus in several cases' samples support its association with AFM. Increased AFM awareness among clinicians, adequate diagnostics and case registration matter to monitor the incidence.

Clinical presentation, electrodiagnostic findings and outcomes of acute flaccid myelitis: A brief review and case series.

Acute flaccid myelitis (AFM) is an acute condition occurring mostly in children. Although affected patients can show a broad spectrum of symptoms, it is mainly characterized by the progressive onset of focal limb weakness, presenting over a period of hours to a week, with or without pain, and spinal cord gray matter involvement on magnetic resonance imaging (MRI). There is compelling evidence to support the role of viruses, in particular enteroviruses. Studies describing electrodiagnostic (EDX) abnormalities and long-term outcomes in AFM are limited. In this report, the clinical presentation, EDX and MRI findings, and long-term outcomes in three children with AFM who presented with progressive and asymmetric weakness of the limbs are described. MRI showed a long segment cervicothoracic lesion with vertical expansion in all three cases. Patients do recover in time, but many continue to have permanent muscle weakness in the worst affected part(s), and complete recovery is rare. Follow-up of these three cases at 18 months demonstrated a partial recovery in the motor system.

Detection of intrathecal antibodies to diagnose enterovirus infections of the central nervous system.

BACKGROUND: Enterovirus-D68 (EV-D68) predominantly causes respiratory disease. However, EV-D68 infections also have been associated with central nervous system (CNS) complications, most specifically acute flaccid myelitis (AFM). Diagnosing EV-D68-associated CNS disease is challenging since viral RNA is rarely detected in cerebrospinal fluid (CSF). OBJECTIVE: In order to determine an EV antibody index (AI), we evaluated the value of a commercially available quantitative ELISA to detect EV-specific antibodies in paired CSF and blood. STUDY DESIGN: Nine paired CSF and blood samples were obtained from patients with EV-D68-associated AFM or from patients with a confirmed EV-associated CNS disease. EV-specific antibodies were detected using a quantitative ELISA. A Reiber diagram analysis was performed, by which the AI was calculated. Subsequently, EV ELISA results were compared with an EV-D68 virus neutralization test. RESULTS: ELISA detected EV-specific antibodies in 1 out of the 3 patients with EV-D68-associated AFM and in 3 out of the 6 patients with confirmed EV-associated CNS disease. In these patients, the AI was indicative for intrathecal antibody production against enterovirus. Assay comparison showed that EV-D68 neutralizing antibody detection increased the sensitivity of EV-D68 antibody detection. CONCLUSIONS: A quantitative EV IgG ELISA in combination with Reiber diagram analysis and AI-calculation can be used as a diagnostic tool for EV-associated CNS disease, including EV-D68. An EV-D68 specific ELISA will improve the sensitivity of the tool. With the growing awareness that the detection of non-polio enteroviruses needs to be improved, diagnostic laboratories should consider implementation of EV serology.

A Review of the Diagnosis and Management of Acute Flaccid Myelitis in the Emergency Department.

ABSTRACT: Since 2014, biennial rises in acute flaccid myelitis (AFM) have brought attention to this rare but debilitating condition. Children with AFM typically present with acute onset, flaccid weakness accompanied by longitudinally extensive gray matter injury demonstrated on magnetic resonance imaging. A clearer understanding of the epidemiology and suspected pathogenesis of AFM may result in increased recognition. The purpose of this review article is to guide emergency physicians in recognizing key clinical features, initiating diagnostic evaluation and providing appropriate interventions for children with suspected AFM.

[Infection of the central nervous system by Epstein-Barr virus: clinical manifestations and prognosis]. / Infección del sistema nervioso central por el virus de Epstein-Barr: manifestaciones clínicas y pronóstico.

INTRODUCTION: The role of Epstein-Barr virus (EBV) in central nervous system (CNS) infections is not fully resolved. We wanted to describe the clinical manifestations of patients with EBV infection in cerebrospinal fluid. PATIENTS AND METHODS: We reviewed the clinical records of all adult patients EBV PCR-positive in cerebrospinal fluid, without lymphoproliferative disease, during 2004 to 2020. RESULTS: We identified 27 patients, 22 (81.5%) were men, and median age was 54 years. Twenty-three (82.1%) patients were immunosuppressed, 16 HIV-positive. In 15 (55.6%) patients coinfection with another microorganism was diagnosed and in 12 (44.4%) patients it was detected as the only pathogen. Of the 12 patients, three (25%) was immunocompetent patients, one had Guillain Barre syndrome (GBS), another had disseminated multiphasic encephalitis, and another had lymphocytic meningitis; 9 (75%) immunosuppressed, 7 HIV-positive, 4 had encephalitis that resolved without sequelae and 4 had encephalopathy, two HIH-positive had moderate cognitive impairment as a sequela. CONCLUSIONS: In our study, EBV produced encephalitis, meningitis, polyradiculomyelitis and GBS, mainly in immunosuppressed patients. In more than half of the cases, it is associated with other pathogens where the role of EBV is unclear. In immunocompetent patient, the infection can be serious and leave sequelae and in HIV-positive patients with encephalopatic involvement without encephalitis, the neurological damage could be greater, so we consider it of interest to carry out studies to evaluate the prognosis as well as the role of antivirals in the evolucion of these clinical pictures.

TITLE: Infección del sistema nervioso central por el virus de Epstein-Barr: manifestaciones clínicas y pronóstico.Introducción. El papel del virus de Epstein-Barr (VEB) en las infecciones del sistema nervioso central no siempre está claro. Nuestro objetivo fue describir las manifestaciones clínicas y la evolución de los pacientes con detección del VEB en el líquido cefalorraquídeo (LCR). Pacientes y métodos. Se revisaron las historias clínicas de todos los pacientes adultos con detección del VEB en el LCR por reacción en cadena de la polimerasa diagnosticados desde 2004 hasta 2020 sin enfermedad linfoproliferativa. Resultados. Se diagnosticó a 27 pacientes, 22 (81,5%) hombres, con una mediana de 54 años; 23 (82,1%) pacientes eran inmunodeprimidos, 16 positivos para el virus de la inmunodeficiencia humana (VIH). En 15 (55,6%) pacientes, el VEB se detectó en coinfección con otro microorganismo, y en 12, como único patógeno. De los 12 pacientes, tres (25%) eran inmunocompetentes, uno presentó un síndrome de Guillain-Barré, otro una encefalitis diseminada multifásica y otro una meningitis linfocitaria; y nueve (75%) inmunodeprimidos, de los que cuatro presentaron encefalitis que se resolvieron sin secuelas, y cuatro encefalopatía, dos de ellos positivos para el VIH, que presentaron secuelas (deterioro cognitivo moderado). Conclusiones. En nuestro estudio, el VEB produjo cuadros de encefalitis, meningitis, polirradiculomielitis y SGB, principalmente en inmunodeprimidos. En más de la mitad de los casos se asocia a otros patógenos, en donde el papel del VEB no está claro. En inmunocompetentes, las infecciones pueden ser graves y dejar secuelas, y en pacientes con VIH con encefalopatía sin encefalitis, el daño neurológico podría ser mayor, por lo que consideramos de interés realizar estudios que evalúen el pronóstico y el papel de los antivirales en la evolución de estos cuadros clínicos.

[Acute flaccid myelitis and enterovirus infection: a severe emerging disease]. / Mielitis flácida aguda e infección por enterovirus: una enfermedad grave emergente.

Acute flaccid myelitis (AFM) is a neuroinflammatory disease characterized by acute asymmetric weakness of the limbs associated with lesions of the gray matter of the spinal cord. It mainly affects children and has been increasingly identified since 2014. OBJECTIVE: To describe a severe emerging neurological disease in Chile. CLINICAL CASE: Three children (2 females), previously healthy were in cluded. The age at the onset was between 4 and 6 years. All presented an acute febrile illness associated with upper respiratory symptoms, rapid onset of proximal asymmetric limb weakness, spinal fluid pleocytosis, and enterovirus isolated from nasopharyngeal swab; two patients developed tetraparesis. The MRI of the spinal cord showed T2 hyperintensity of the grey matter. The three patients were admitted to the Pediatric Intensive Care Unit (PICU), and two required mechanical ventilation. No significant improvements were observed after the use of immunomodulatory therapy and plasma ex change. At 12 months of follow-up, one case was quadriplegic and ventilator-dependent; the second died of ventricular arrhythmia in the PICU, and the third one is under rehabilitation with partial recovery. CONCLUSIONS: We report the first cases of this severe emerging neurological disease in our country. In a child with predominantly proximal and asymmetric acute limb paralysis, pediatricians must have a high index of suspicion for AFM. Since it can progress rapidly and lead to respiratory failure, suspected AFM should be considered a medical emergency.

Acute flaccid myelitis and Guillain-Barré syndrome in children: A comparative study with evaluation of diagnostic criteria.

BACKGROUND AND PURPOSE: Differentiation between acute flaccid myelitis (AFM) and Guillain-Barré syndrome (GBS) can be difficult, particularly in children. Our objective was to improve the diagnostic accuracy by giving recommendations based on a comparison of clinical features and diagnostic criteria in children with AFM or GBS. METHODS: A cohort of 26 children with AFM associated with enterovirus D68 was compared to a cohort of 156 children with GBS. The specificity of the Brighton criteria, used for GBS diagnosis, was evaluated in the AFM cohort and the specificity of the Centers for Disease Control and Prevention (CDC) AFM diagnostic criteria in the GBS cohort. RESULTS: Children with AFM compared to those with GBS had a shorter interval between onset of weakness and nadir (3 vs. 8 days, p < 0.001), more often had asymmetric limb weakness (58% vs. 0%, p < 0.001), and less frequently had sensory deficits (0% vs. 40%, p < 0.001). In AFM, cerebrospinal fluid leukocyte counts were higher, whereas protein concentrations were lower. Spinal cord lesions on magnetic resonance imaging were only found in AFM patients. No GBS case fulfilled CDC criteria for definite AFM. Of the AFM cases, 8% fulfilled the Brighton criteria for GBS, when omitting the criterion of excluding an alternate diagnosis. CONCLUSIONS: Despite the overlap in clinical presentation, we found distinctive early clinical and diagnostic characteristics for differentiating AFM from GBS in children. Diagnostic criteria for AFM and GBS usually perform well, but some AFM cases may fulfill clinical diagnostic criteria for GBS. This underlines the need to perform diagnostic tests early to exclude AFM in children suspected of atypical GBS.

Does acute flaccid myelitis cause respiratory failure in children?

INTRODUCTION: Acute flaccid myelitis (AFM) is a rare disease that affects spinal cord gray matter, results in acute flaccid weakness of one or more limbs and predominantly involves the cervical spinal cord, which places patients at higher risk for respiratory failure. Our study aims to describe respiratory failure in pediatric AFM patients with emphasis on the need for assisted ventilation and respiratory nerve involvement from an acute and long-term perspective. MATERIALS AND METHODS: We reviewed the medical records of patients diagnosed with AFM seen in a multidisciplinary clinic for persistent limb weakness between 2016 and 2020. RESULTS: We studied 54 patients, 35% were female. The median age of patients at illness onset was 5 years (range 7 months-19 years). The median age of patients at the time of study was 8.5 years (range 2-20 years). Eleven patients (20%) required assisted ventilation for acute respiratory failure. Of those that experienced acute respiratory failure, 81% developed chronic respiratory failure. Fifty-six percent of patients with chronic respiratory failure were able to wean off assisted ventilation by 1 year. All patients that experienced unilateral diaphragm impairment with AFM onset experienced acute and chronic respiratory failure. DISCUSSION: Many patients with AFM may experience respiratory compromise and develop chronic respiratory failure. However, most of these patients can be weaned off ventilatory support by 1 year from illness onset. Most children with unilateral diaphragm impairment can sustain adequate ventilation without the need for long-term ventilatory support.

Using the Acute Flaccid Paralysis Surveillance System to Identify Cases of Acute Flaccid Myelitis, Australia, 2000‒2018.

Since 2012, the United States has reported a distinct syndrome of acute flaccid paralysis (AFP) with anterior myelitis, predominantly in children. This polio-like syndrome was termed acute flaccid myelitis (AFM). Australia routinely conducts AFP surveillance to exclude poliomyelitis. We reviewed 915 AFP cases in Australia for children <15 years of age during 2000‒2018 and reclassified a subset to AFM by using the US Council of State and Territorial Epidemiologists case definition. We confirmed 37 AFM cases by using magnetic resonance imaging findings and 4 probable AFM cases on the basis of cerebrospinal fluid pleocytosis. Nonpolio enteroviruses were detected in 33% of AFM cases from which stool samples were tested. Average annual AFM incidence was 0.07 cases/100,000 person-years in children <15 years of age. AFM occurred sporadically in Australia before 2010 but regularly since then, indicating sustained, albeit rare, clinical manifestation in children. The AFP surveillance system in Australia is well-positioned to identify future AFM cases.