Incidence, Risk Factors and Outcomes Among Children With Acute Flaccid Myelitis: A Population-based Cohort Study in a California Health Network Between 2011 and 2016

Neuromuscular problems of the critically Ill neonate and child

Acute neuromuscular disorders occasionally occur in the Pediatric Neurologic Intensive Care Unit. Many of these are primary disorders of the motor unit that may present acutely or exacerbate during an intercurrent illness. Additionally, acute neuromuscular disorders may develop during an acute systemic illness requiring intensive care management that predispose the child to another set of acute motor unit disorders. This chapter discusses acute neuromuscular crises in the infant, toddler, and adolescent, as well as neuromuscular disorders resulting from critical illness.

Enterovirus A71-associated acute flaccid paralysis in a pediatric patient: a case report

BACKGROUND

Enterovirus A71 is one of the causative agents of hand, foot, and mouth disease, which is usually a self-limiting disease. Complications of enterovirus infection are also very rare. However, when such complications occur, they can lead to serious neurological diseases or even death.

CASE PRESENTATION

In this report, we describe a case of enterovirus A71-associated acute flaccid paralysis in a 13-month-old Caucasian girl that was managed in our hospital. The patient presented with sudden onset of left arm paresis that could not be attributed to any other cause. Establishing a diagnosis was furthermore complicated by negative virological investigations of cerebrospinal fluid and non-pathological radiological findings. A polymerase chain reaction test of the child's stool sample however tested positive for enterovirus and sequencing results revealed the presence of enterovirus A71. A previous history of febrile gastroenteritis just before the paresis started also supported the suspected diagnosis of enterovirus-associated acute flaccid paralysis. Following this, the child was treated with intravenous immunoglobulin over 5 days and a remarkable improvement was observed in the child's paresis.

CONCLUSION

This case report describes a possible complication of enterovirus A71 infection in a child. It also highlights the prolonged detection of enterovirus in the child's stool sample as compared with cerebrospinal fluid weeks after the primary infection occurred. Finally, it shows the need for increased clinical and diagnostic awareness especially in the management of sudden and unknown causes of paresis or paralysis in children.

Acute flaccid myelitis in Switzerland - association with enterovirus D68

Poliomyelitis-like acute flaccid myelitis associated with enterovirus D68 (EV-D68) has emerged globally during the past decade. Here we describe the first documented case reported from Switzerland, and a second, suspected case occurring in temporal association. AFM occurs primarily in children, is usually heralded by a febrile, respiratory prodrome followed by acute-onset, usually asymmetrical, limb weakness with some predilection for the upper extremities, and respiratory muscle compromise in one third of reported cases. There is no specific therapy and the majority of cases result in permanent neurological sequelae. A comprehensive diagnostic workup and timely reporting to the health authorities are essential. Surveillance of respiratory and stool samples for EV-D68 and other neurotropic enteroviruses is in place in several European countries and warrants consideration in Switzerland. This could entail the extension of the poliomyelitis surveillance program of the Federal Office of Public Health by monitoring and enteroviral typing of respiratory samples from patients with acute flaccid paralysis.

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.

Acute Flaccid Myelitis: Review of Clinical Features, Diagnosis, and Management with Nerve Transfers

BACKGROUND

Acute flaccid myelitis (AFM) is a devastating neurologic condition in children, manifesting as acute limb weakness and/or paralysis. Despite increased awareness of AFM following initiation of U.S. surveillance in 2014, no treatment consensus exists. The purpose of this systematic review was to summarize the most current knowledge regarding AFM epidemiology, cause, clinical features, diagnosis, and supportive and operative management, including nerve transfer.

METHODS

The authors systematically reviewed the literature based on Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines using multiple databases to search the keywords ("acute flaccid myelitis"), ('acute flaccid myelitis'/exp OR 'acute flaccid myelitis'), and (Acute AND flaccid AND myelitis). Included articles reported on (1) AFM diagnosis and (2) patient-specific data regarding epidemiology, cause, clinical features, diagnostic features, or management of AFM.

RESULTS

Ninety-nine articles were included in this review. The precise cause and pathophysiologic mechanism of AFM remain undetermined, but AFM is strongly associated with nonpolio enterovirus infections. Clinical presentation typically comprises preceding viral prodrome, pleocytosis, spinal cord lesions on T2-weighted magnetic resonance imaging, and acute onset of flaccid weakness/paralysis with hyporeflexia in at least one extremity. Supportive care includes medical therapy and rehabilitation. Early studies of nerve transfer for AFM have shown favorable outcomes for patients with persistent weakness.

CONCLUSIONS

Supportive care and physical therapy are the foundation of a multidisciplinary approach to managing AFM. For patients with persistent limb weakness, nerve transfer has shown promise for improving function in distal muscle groups. Surgeons must consider potential spontaneous recovery, patient selection, donor nerve availability, recipient nerve appropriateness, and procedure timing.

Acute flaccid myelitis a review of the literature

Acute flaccid myelitis (AFM) is a rare neurological disorder that first rose to national attention in 2014. This neurological disorder has a biennial presentation with every other even year being a peak year. Most patients present in childhood 5 days after a prodromal infection. Patients usually present with muscle weakness and hypo or areflexia in the summer or fall months. Clinical outcomes are variable however most patients do not improve. Currently there are no definitive prognostic factors or etiologies found. However, it is thought that enterovirus-D68 (EV-D68) could be a potential component in the pathobiology of AFM. Treatment options are limited with variable options and no consensus. Supportive therapy has been shown to be the most effective thus far. With our review of the literature, we highlight the recent growing evidence of a possible relationship between EV-D68 and AFM. Additionally, we identify the knowledge gaps in AFM with treatment and prognostic factors.

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

Background

Acute 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.

Aim

To report AFM incidence in children in the Netherlands and its occurrence relative to EV-D68 and EV-A71 detections.

Methods

In 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.

Results

Among 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.

Conclusions

AFM 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.

An Overview of Acute Flaccid Myelitis

Acute Flaccid Myelitis is defined by the presence of Acute Flaccid Paralysis (AFP) and a spinal cord lesion on magnetic resonance imaging that is primarily limited to the grey matter. AFM is a difficult situation to deal with when you have a neurologic illness. According to the Centers for Disease Control and Prevention (CDC), a large number of cases were discovered in the United States in 2014, with 90% of cases occurring in children. Although the exact cause of AFM is unknown, mounting evidence suggests a link between AFM and enterovirus D68 (EV-D68). In 2014, an outbreak of AFM was discovered in the United States. The condition was initially linked to polioviruses; however, it was later found that the viruses were caused by non-polioviruses Enteroviruses D-68 (EV-D68). The number of cases has increased since 2014, and the disease has been declared pandemic in the United States. The sudden onset of muscle weakness, usually in an arm or leg, as well as pain throughout the body, the change in patient's facial expression (facial weakness), and shortness of breath, ingesting, and speaking are all common symptoms in patients suffering from neurologic disease. This article includes graphic and histogram representations of reported AFM incidents and criteria for causality, epidemiology, various diagnostic approaches, signs and symptoms, and various investigational guidelines. It also includes key statements about recent clinical findings related to AFM disease.

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.

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.

Acute Flaccid Myelitis

Acute flaccid myelitis (AFM) is an incompletely understood neurologic disorder occurring in epidemic fashion causing weakness ranging from mild paresis to devastating paralysis in children and some adults. This article reviews the case definition of AFM as well as its epidemiology and association with enteroviral infection. The clinical presentation, diagnostic investigation with particular attention to electrodiagnostics, acute management, and surgical options are described. Clinical outcomes and considerations for acute and long-term rehabilitation management are discussed extensively based on review of current literature, highlighting avenues for further study.

Three-Year Longitudinal Motor Function and Disability Level of Acute Flaccid Myelitis

BACKGROUND

We summarize the long-term motor outcome and disability level in a cluster of pediatric patients with acute flaccid myelitis (AFM) associated with the enterovirus D68 outbreak in 2015.

METHODS

This is a nationwide follow-up questionnaire analysis study. Clinical data including the motor function (manual muscle strength test) and other neurological symptoms were collected at the acute (nadir), recovery (six months), and chronic (three years) stages. We use the Barthel index, which measures 10 variables describing activity of daily living and mobility to assess the disability level.

RESULTS

Clinical data of 33 patients with AFM (13 females, 20 males; median age = 4.1 years) were available. Among patients with tetraplegia or triplegia, paraplegia, and monoplegia at the acute stage, two of seven, four of thirteen, and two of thirteen exhibited complete recovery without paralysis; of those five of seven, eight of thirteen, and two of thirteen showed improvement with lesser limb involvement at the chronic stage, respectively. Nine patients (27%) demonstrated improvement at the recovery-to-chronic period. All six patients with positive isolation of enterovirus D68 from biological samples at the acute stage showed persistent motor deficits. Other neurological findings had better prognosis than motor weakness. Better Barthel index score at the chronic stage was observed (P < 0.001; median difference [95% confidence interval], 53 [40 to 63]), implying an improved disability level even in patients with persistent motor deficits.

CONCLUSIONS

AFM has a high rate of persistent motor deficits showing one- to two-limb paralysis. Disability level of patients with AFM, however, generally improved at the three-year time point.

Improvements in Function Following Inpatient Activity-Based Therapy for Children With Acute Flaccid Myelitis

BACKGROUND

Acute flaccid myelitis (AFM) is an illness defined by rapid onset of flaccid paralysis in one or more limbs or bulbar muscles, with MRI findings of predominantly spinal cord gray matter abnormalities spanning one or more spinal segments following a viral illness. Individuals with AFM may require rehabilitation to promote recovery. Activity-based restorative therapy (ABRT) has previously been shown to result in positive outcomes in children with neurologic deficits related to AFM.

OBJECTIVES

This study examined functional changes in a group of children with AFM who participated in ABRT in an inpatient setting.

METHODS

Retrospective chart review of children with AFM admitted to a single inpatient rehabilitation unit from 2014 to 2018. Children were assessed using the Functional Independence Measure for Children (WeeFIM), Manual Muscle Testing (MMT), Spinal Cord Independence Measure (SCIM), and the Physical Abilities and Mobility Scale (PAMS) as part of routine clinical care; the Modified Rankin Scale for Neurologic Disability was completed retrospectively.

RESULTS

Children showed significant improvements across all outcome measures, with effect sizes ranging from moderate to large. Significant change was also seen across all muscle groups on MMT, with effect sizes ranging from small to large. Consistent with previous reports, children demonstrated better function in distal than proximal muscle groups at both admission and discharge.

CONCLUSION

Children with AFM who participated in ABRT increased muscle strength and made functional gains across all outcome measures. These results support the utility of rehabilitation in the long-term care of children with AFM and residual neurologic deficit.

Acute flaccid myelitis outbreak through 2016-2018: A multicenter experience from Turkey

AIM

We aim to describe the demographic characteristics, etiology, neurophysiology, imaging findings, treatment, prognosis, and prognostic factors of acute flaccid myelitis.

METHODS

The clinical data, laboratory test and, magnetic resonance imaging (MRI) results of pediatric patients diagnosed with acute flaccid myelitis according to the Centers for Disease Control criteria between August 1, 2016, and December 31, 2018, from 13 centers in Turkey were reviewed.

RESULTS

Of the 34 cases identified, 31 were confirmed (91.2%). Eighteen patients (55.9%) were boys. The median patient age was 4 years (interquartile range 2.5-6.9 years). Most of the patients were admitted in 2018 (n = 27). A preceding history of a febrile illness was reported in all patients, with a median of 4 days (interquartile range 3-7 days) before symptom onset. Thirty-one patients had T2 hyperintensity on spinal MRI, and 18 patients had cerebrospinal fluid pleocytosis. The most common infectious agents were entero/rhinoviruses (n = 5) in respiratory specimens. All patients except one received immunotherapy either alone or in combination. Among 27 patients with follow-up data 24 had persistent weakness. Involvement of four limbs together with an abnormal brain MRI at onset were associated with a poor prognosis.

CONCLUSION

The number of patients with acute flaccid myelitis increased since 2012, spiking with every 2-year interval, largely in the pediatric population. The median age decreases with every outbreak. Clinicians should be aware of the clinical picture for early collection of specimens and early start of rehabilitation programs. Further studies are needed to better characterize the etiology, pathogenesis, risk factors, and treatment of this rare condition.

Update on acute flaccid myelitis: recognition, reporting, aetiology and outcomes

Acute flaccid myelitis, defined by acute flaccid limb weakness in the setting of grey matter lesions of the spinal cord, became increasingly recognised in 2014 following outbreaks in Colorado and California, temporally associated with an outbreak of enterovirus D68 respiratory disease. Since then, there have been biennial increases in late summer/early fall. A viral infectious aetiology, most likely enteroviral, is strongly suspected, but a definitive connection has yet to be established. Patients typically present with asymmetric weakness, maximal proximally, in the setting of a febrile illness. MRI demonstrates T2/FLAIR abnormalities in the central grey matter of the spinal cord, and cerebrospinal fluid typically shows a lymphocytic pleocytosis with variable elevation in protein. The weakness may be progressive over several days and involve respiratory muscles, making early recognition and close monitoring essential. Other complications in the acute period may include autonomic instability and bowel/bladder involvement. There is no clear recommended treatment at this time, although intravenous immunoglobulin, steroids and plasma exchange have been used. Intensive therapies and rehab services have shown benefit in maximising function, and surgical interventions may be considered in cases without optimal response to therapies. Close attention should also be paid to psychosocial factors. Prognosis is generally guarded, and additional factors that predict final outcome, including host factors and treatment effects, have yet to be elucidated. Multicentre collaborative efforts will be required to provide answers about this rare but serious disorder.

Enterovirus infection and acute flaccid myelitis

Recent outbreaks of limb paralysis similar to poliomyelitis, termed acute flaccid myelitis (AFM), have prompted intense investigation into potential etiology. Peaks of AFM were seen in the United States in 2012, 2014, 2016 and 2018, coincident with peaks in enterovirus transmission, particularly EV-D68. Similar peaks of AFM and EV-D68 circulation were reported in other parts of the world. The causal relationship between EV-D68 is still not widely accepted as it is for poliovirus and EV-A71, the latter of which is endemic in the US. Recent in vitro and mouse model data as well as enhanced-sensitivity diagnostic assays have provided further evidence linking the causal relationship between EV-D68 and AFM. In addition, an outbreak of EV-A71-associated AFM was recently described, highlighting the possibility of an additional emerging non-polio enterovirus of public health concern. As AFM is a devastating disease with poor prognosis in many children, particularly those with EV-D68, recent studies call for increased surveillance, pursuit of novel therapeutics and strategies to prevent transmission before the next outbreak.

Acute flaccid myelitis and enterovirus D68: lessons from the past and present

Acute flaccid myelitis is characterized by the combination of acute flaccid paralysis and a spinal cord lesion largely restricted to the gray matter on magnetic resonance imaging. The term acute flaccid myelitis was introduced in 2014 after the upsurge of pediatric cases in the USA with enterovirus D68 infection. Since then, an increasing number of cases have been reported worldwide. Whereas the terminology is new, the clinical syndrome has been recognized in the past in association with several other neurotropic viruses such as poliovirus.Conclusion: This review presents the current knowledge on acute flaccid myelitis with respect to the clinical presentation and its differential diagnosis with Guillain-Barré syndrome and acute transverse myelitis. We also discuss the association with enterovirus D68 and the presumed pathophysiological mechanism of this infection causing anterior horn cell damage. Sharing clinical knowledge and insights from basic research is needed to make progress in diagnosis, treatment, and prevention of this new polio-like disease. What is Known: • Acute flaccid myelitis (AFM) is a polio-like condition characterized by rapid progressive asymmetric weakness, together with specific findings on MRI • AFM has been related to different viral agents, but recent outbreaks are predominantly associated with enterovirus D68. What is New: • Improving knowledge on AFM must increase early recognition and adequate diagnostic procedures by clinicians. • The increasing incidence of AFM urges cooperation between pediatricians, neurologists, and microbiologists for the development of treatment and preventive options.