Comparative quantitative clinical, neuroimaging, and functional profiles in children with acute flaccid myelitis at acute and convalescent stages of disease

Update in Pediatric Neurocritical Care: What a Neurologist Caring for Critically Ill Children Needs to Know

Currently nearly one-quarter of admissions to pediatric intensive care units (PICUs) worldwide are for neurocritical care diagnoses that are associated with significant morbidity and mortality. Pediatric neurocritical care is a rapidly evolving field with unique challenges due to not only age-related responses to primary neurologic insults and their treatments but also the rarity of pediatric neurocritical care conditions at any given institution. The structure of pediatric neurocritical care services therefore is most commonly a collaborative model where critical care medicine physicians coordinate care and are supported by a multidisciplinary team of pediatric subspecialists, including neurologists. While pediatric neurocritical care lies at the intersection between critical care and the neurosciences, this narrative review focuses on the most common clinical scenarios encountered by pediatric neurologists as consultants in the PICU and synthesizes the recent evidence, best practices, and ongoing research in these cases. We provide an in-depth review of (1) the evaluation and management of abnormal movements (seizures/status epilepticus and status dystonicus); (2) acute weakness and paralysis (focusing on pediatric stroke and select pediatric neuroimmune conditions); (3) neuromonitoring modalities using a pathophysiology-driven approach; (4) neuroprotective strategies for which there is evidence (e.g., pediatric severe traumatic brain injury, post-cardiac arrest care, and ischemic stroke and hemorrhagic stroke); and (5) best practices for neuroprognostication in pediatric traumatic brain injury, cardiac arrest, and disorders of consciousness, with highlights of the 2023 updates on Brain Death/Death by Neurological Criteria. Our review of the current state of pediatric neurocritical care from the viewpoint of what a pediatric neurologist in the PICU needs to know is intended to improve knowledge for providers at the bedside with the goal of better patient care and outcomes.

Acute Flaccid Myelitis: Mid-Term Clinical Course of Knee Extension Paralysis and Outcomes of Nerve Transfer

BACKGROUND

Acute flaccid myelitis (AFM) is a rare debilitating poliomyelitis-like illness characterized by the sudden onset of flaccid palsy in the extremities. The purpose of this study was to report the mid-term clinical course of knee extension in AFM and the effect of contralateral obturator nerve-to-femoral nerve transfer (CONFNT) for restoration of knee extension in AFM.

METHODS

Twenty-six patients with lower extremity palsy due to AFM were referred to our clinic for possible surgical reconstruction. Their median age was 4.0 years, and the first evaluation of the palsy was done at a mean of 6 months after paralysis onset. The paralysis ranged from lower limb monoplegia to quadriplegia. The clinical course of knee extension was assessed using the British Medical Research Council (MRC) grading scale and surface electromyography (EMG). Five patients with unilateral paralysis of knee extension underwent CONFNT.

RESULTS

The mean follow-up period for 19 limbs with complete paralysis of knee extension (MRC grade M0) in 13 patients who were evaluated for spontaneous recovery was 43 months. No patient who had complete paralysis of knee extension at >6 months and paralysis of the hip adductor muscle had improvement of knee extension to better than M2. Five of the original 26 patients were treated with CONFNT and followed for a mean of 61 months. Two of 5 patients had the CONFNT ≤8 months after paralysis onset and obtained M4 knee extension. Only 1 of the 3 patients with CONFNT performed approximately 12 months after paralysis onset obtained M3 knee extension; the other 2 obtained only M1 or M2 knee extension.

CONCLUSIONS

The paralysis of the lower extremity in our patients with AFM was similar to that in poliomyelitis. However, in AFM, spontaneous recovery of knee extension was possible if there were signs of recovery from hip adductor paralysis up to 6 months after paralysis onset. CONFNT may enhance the recovery of knee extension and seems to be a reliable reconstruction for restoring knee extension if performed no more than 8 months after paralysis onset.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Midterm Outcomes of Surgical Reconstruction and Spontaneous Recovery of Upper-Extremity Paralysis Following Acute Flaccid Myelitis

Background

Acute flaccid myelitis (AFM) is a disabling, poliomyelitis-like illness that mainly affects children. Although various surgical interventions are performed for intractable paralysis due to AFM, the timing of surgery and its long-term outcomes have yet to be established, especially for shoulder reconstruction. This study aimed to analyze the midterm outcomes of nonsurgically and surgically treated upper-extremity AFM and the factors influencing shoulder functional outcomes after surgical reconstruction.

Methods

We retrospectively examined 39 patients with AFM in 50 upper extremities between 2011 and 2019. The degree of spontaneous recovery of completely paralyzed muscles was evaluated at a median of 3, 6, and 37 months after the onset of paralysis. Twenty-seven patients with 29 extremities underwent surgery involving nerve transfer, muscle-tendon transfer, or free muscle transfer for shoulder, elbow, and hand reconstruction.

Results

Patients with complete paralysis of shoulder abduction at 6 months did not show later recovery. Twenty-two patients with 24 extremities underwent shoulder surgery, and all but 1 were followed for at least 24 months after surgery. Although postoperative shoulder abduction recovery was similar between transfer of the spinal accessory nerve and of the contralateral C7 nerve root to the suprascapular nerve, the outcomes obtained with spinal accessory nerve transfer had more variability, likely related to latent spinal accessory nerve paralysis, shoulder instability related to pectoralis major paralysis, and the type of paralysis. Shoulder abduction recovery was also greatly affected by scapulothoracic joint movement. In contrast, the outcomes of the elbow flexion and hand reconstructions were more consistent and acceptable.

Conclusions

All patients had loss of shoulder abduction, and restoration of shoulder function was less predictable and depended on the quality of the donor nerves and recovery of the synergistic muscles. Strict donor nerve selection and additional nerve transfer for shoulder reconstruction are imperative for satisfactory outcomes.

Level of Evidence

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Nerve Transfer Surgery in Acute Flaccid Myelitis: Prognostic Factors, Long-Term Outcomes, Comparison With Natural History

BACKGROUND

Nerve transfer surgery is sometimes offered to patients with acute flaccid myelitis (AFM). The objectives of this study were to evaluate surgical efficacy, assess which clinical and neurophysiological data are valuable for preoperative planning, and report long-term outcomes.

METHODS

This is a single-center, retrospective case series of patients with AFM who received nerve transfer surgery. All patients had preoperative electromyography and nerve conduction studies (EMG/NCS). Matched control muscles that did not receive nerve transfer surgery were defined in the same cohort.

RESULTS

Ten patients meeting inclusion criteria received a total of 23 nerve transfers (19 upper extremity, four lower extremity). The mean age at symptom onset was 3.8 years, surgery was 0.5 to 1.25 years after diagnosis, and mean follow-up was 2.3 years (range 1.3 to 4.5 years). Among muscles with preoperative strength Medical Research Council (MRC) grade 0, muscles receiving nerve transfers performed significantly better than those that did not (MRC grade 2.17 ± 0.42 vs 0 ± 0, respectively, P = 0.0001). Preoperative EMG/NCS predicted worse outcomes in recipient muscles with more abundant acute denervation potentials (P = 0.0098). Donor nerves found to be partially denervated performed equally well as unaffected nerves. Limited data suggested functional improvement accompanying strength recovery.

CONCLUSIONS

Nerve transfer surgery is an effective strategy to restore strength for patients with AFM with persistent, severe motor deficits. Postoperative outcomes in patients with complete paralysis are better than the natural history of disease. This study demonstrates the utility of preoperative clinical and electrophysiological data in guiding patient selection for nerve transfer surgery.

Brain Magnetic Resonance Imaging Abnormalities in Acute Flaccid Myelitis

BACKGROUND

Acute flaccid myelitis (AFM) presents with acute onset of flaccid paralysis with involvement of the gray matter on magnetic resonance imaging (MRI) of the spinal cord. Studies have reported brain MRI abnormalities, but the characteristics have not been fully defined. In this multicenter study, we assessed the acute features and evolution of brain MRI abnormalities in AFM.

METHODS

We reviewed brain MRIs of patients with AFM who presented to four referral hospitals between 2012 and 2018. Cases met established criteria for AFM. We analyzed the initial and follow-up brain MRIs. Areas were divided into supratentorial, infratentorial, and subdivisions within those regions.

RESULTS

A total of 66 patients were included. Brain MRI abnormalities were present in 34 (52%). Infratentorial abnormalities were more common, occurring in 33 (97%) cases with the dorsal pons being the most frequently affected area (88%). Abnormalities were also present in the medulla (74%), cerebellum (41%), and midbrain (38%). Nine subjects (26%) exhibited both supratentorial and infratentorial abnormalities, whereas isolated supratentorial changes were present in only one (3%). Contrast-enhancing abnormalities were encountered in 9% of cases and meningeal involvement in 6%. On follow-up, most abnormalities, 20 of 24 (83%), were stable, improving, or had resolved.

CONCLUSIONS

Brain MRI abnormalities occur in about half of the cases of AFM and commonly resolve with time. Dorsal pontine involvement is a characteristic MRI feature, whereas isolated supratentorial abnormalities are rare. Clinicians should consider that brain imaging abnormalities do not exclude a diagnosis of AFM in patients with typical presentations.

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.

Six- and 12-month functional outcomes among patients with confirmed acute flaccid myelitis (AFM) with onset in 2018, United States

PURPOSE

Acute flaccid myelitis (AFM), an uncommon but serious neurologic condition, primarily affects children, and can progress quickly to paralysis and respiratory failure. Data on long-term outcomes of patients with AFM are limited. This study reports on functional status through 12 months for AFM patients who became ill in 2018 in the United States.

METHODS

Health departments collected information on outcomes at 6 and 12 months after onset of AFM using a standardized form that asked patients or their parents/guardians about functional status. Analyses were restricted to confirmed cases.

RESULTS

Of the 238 confirmed AFM cases reported to CDC in 2018, 90 (38%) had assessments at 6 months, 82 (34%) at 12 months, and 49 (21%) at both 6 and 12 months. Among the 49 patients with data at both time points, the proportion of patients reporting significant or severe impairment at 6 months ranged from 2% to 59% depending on the outcome. Although proportions decreased by 12 months and ranged from 2% to 51%, most patients had some impairment at 12 months. No deaths were reported.

CONCLUSION

Six- and 12-month outcomes in patients with onset of AFM in 2018 span a wide range of functionality, particularly of upper and lower extremities. Importantly, improvement appears to occur over time in some patients.

The complete acute and post-acute care course of children affected by acute flaccid myelitis in Western Pennsylvania: A case series

Acute flaccid myelitis (AFM) is a "polio-like" neurologic disorder of the spinal cord gray matter characterized by asymmetric, flaccid limb weakness of rapid onset following prodromal viral illness. It has affected the pediatric population of the United States since 2014, but there is a paucity of literature describing the post-acute comprehensive rehabilitation management that maximizes functional outcomes for patients. This case series attempts to mitigate this by describing the complete acute and post-acute care course of six children diagnosed with AFM in Western Pennsylvania. It is critical that pediatric rehabilitation medicine providers be knowledgeable about the complex medical and rehabilitation management for patients with AFM.

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.

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.

Nerve Transfers for Restoration of Elbow Flexion in Patients With Acute Flaccid Myelitis

PURPOSE

The purpose of this study was to evaluate short- to midterm outcomes of patients with acute flaccid myelitis who underwent nerve transfers for restoration of elbow flexion.

METHODS

Patients with a minimum of 10 months of follow up after undergoing nerve transfers to restore elbow flexion were clinically assessed using the Active Movement Scale (AMS). They were evaluated for any postoperative complications, particularly weakness in the distribution of the donor nerve(s). Fifteen of 25 consecutive patients who were treated using this surgical technique were included in the final analysis.

RESULTS

All patients exhibited poor elbow flexion preoperatively (AMS 0 to 3). At a mean follow up of 17.3 months, 80% (15/25) of patients achieved excellent elbow flexion (AMS 6 or 7); 9 of these 15 had full active range of motion. Two patients achieved good elbow flexion (AMS 5) with antigravity movement to less than 50% of the passive range of motion. No cases of superficial or deep infection were reported, and all patients maintained identical motor function, relative to preoperative status, of the muscles innervated by the donor nerves.

CONCLUSIONS

Nerve transfer surgery has shown promising short- to midterm results for recovery of nerve and muscle function, particularly for the restoration of elbow flexion. We recommend this treatment option for patients not demonstrating clinical improvement after 6 to 9 months of incomplete recovery.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

Surgical Innovations to Restore Function in Pediatric Peripheral Nerve Conditions

Peripheral nerve injuries in children can result in devastating lifelong deficits. Because of the time-sensitive nature of muscle viability and the limited speed of nerve regeneration, early recognition and treatment of nerve injuries are essential to restore function. Innovative surgical techniques have been developed to combat the regenerative length and speed; these include nerve transfers. Nerve transfers involve transferring a healthy, expendable donor nerve to an injured nerve to restore movement and sensation. Nerve transfers are frequently used to treat children affected by conditions, including UE trauma, brachial plexus birth injury, and acute flaccid myelitis. Pediatricians play an important role in the outcomes of children with these conditions through early diagnosis and timely referrals. With this review, we aim to provide awareness of state-of-the-art surgical treatment options that significantly improve the function of children with traumatic nerve injuries, brachial plexus birth injury, and acute flaccid myelitis.

Infection-Related Myelopathies

Recent years have seen growing attention to inflammatory and infectious disorders of the spinal cord, not only due to the discovery of autoantibody-mediated disorders of the spinal cord [e.g., aquaporin-4 immunoglobulin G (IgG) antibodies and myelin oligodendrocyte glycoprotein IgG antibodies], but also due to the emergence of clusters of infection-related myelopathy, now known as acute flaccid myelitis. We review the spectrum of infection-related myelopathies and outline a nosological classification system based on association with infection. We describe the epidemiology and definitions of myelopathies, with a discussion of clinical presentation and neuroimaging features, and then turn to specific discussion of myelopathies due to direct pathogen invasion and those considered to be post- or parainfectious. Expected final online publication date for the Annual Review of Pathology: Mechanisms of Disease, Volume 17 is January 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Lower Extremity Nerve Transfers in Acute Flaccid Myelitis Patients: A Case Series

Acute flaccid myelitis (AFM) is characterized by flaccid paralysis following prodromal symptoms. Complete recovery is rare, and patients typically have residual extremity weakness. This study aimed to describe the technique and outcomes of lower extremity nerve transfers for children with AFM.

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.

Acute flaccid myelitis: cause, diagnosis, and management

Acute flaccid myelitis (AFM) is a disabling, polio-like illness mainly affecting children. Outbreaks of AFM have occurred across multiple global regions since 2012, and the disease appears to be caused by non-polio enterovirus infection, posing a major public health challenge. The clinical presentation of flaccid and often profound muscle weakness (which can invoke respiratory failure and other critical complications) can mimic several other acute neurological illnesses. There is no single sensitive and specific test for AFM, and the diagnosis relies on identification of several important clinical, neuroimaging, and cerebrospinal fluid characteristics. Following the acute phase of AFM, patients typically have substantial residual disability and unique long-term rehabilitation needs. In this Review we describe the epidemiology, clinical features, course, and outcomes of AFM to help to guide diagnosis, management, and rehabilitation. Future research directions include further studies evaluating host and pathogen factors, including investigations into genetic, viral, and immunological features of affected patients, host-virus interactions, and investigations of targeted therapeutic approaches to improve the long-term outcomes in this population.

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.

Enterovirus D68 molecular and cellular biology and pathogenesis

In recent years, enterovirus D68 (EV-D68) has advanced from a rarely detected respiratory virus to a widespread pathogen responsible for increasing rates of severe respiratory illness and acute flaccid myelitis (AFM) in children worldwide. In this review, we discuss the accumulating data on the molecular features of EV-D68 and place these into the context of enterovirus biology in general. We highlight similarities and differences with other enteroviruses and genetic divergence from own historical prototype strains of EV-D68. These include changes in capsid antigens, host cell receptor usage, and viral RNA metabolism collectively leading to increased virulence. Furthermore, we discuss the impact of EV-D68 infection on the biology of its host cells, and how these changes are hypothesized to contribute to motor neuron toxicity in AFM. We highlight areas in need of further research, including the identification of its primary receptor and an understanding of the pathogenic cascade leading to motor neuron injury in AFM. Finally, we discuss the epidemiology of the EV-D68 and potential therapeutic approaches.

Association of outcomes in acute flaccid myelitis with identification of enterovirus at presentation: a Canadian, nationwide, longitudinal study

BACKGROUND

Acute flaccid myelitis (AFM) is characterised by rapid onset of limb weakness with spinal cord grey-matter abnormalities on MRI scan. We aimed to assess whether detection of enterovirus in respiratory or other specimens can help predict prognosis in children with AFM.

METHODS

In this nationwide, longitudinal study, we evaluated the significance of detection of enterovirus in any sample in predicting outcomes in a cohort of Canadian children younger than 18 years presenting with AFM to tertiary paediatric hospitals in Canada in 2014 and 2018. All patients fulfilled the 2015 US Centers for Disease Control and Prevention case definition for definite AFM or probable AFM. Clinical data, laboratory findings, treatment, and neuroimaging results were collected (follow up period up to 5 years). We assessed neurological function and motor outcomes using Kurtzke's Expanded Disability Status Scale (EDSS) and a Weakest Limb Score.

FINDINGS

58 children with AFM (median age 5·1 years, IQR 3·8-8·3) were identified across five of Canada's ten provinces and three territories. 25 (43%) children had enterovirus detected in at least one specimen: 16 (64%) with EV-D68, two (8%) with EV-A71, two (8%) with coxsackievirus, 10 (40%) with untyped enterovirus. Children who were enterovirus positive were more likely than those that were negative to have had quadriparesis (12 [48%] of 25 vs four [13%] of 30; p=0·028), bulbar weakness (11 [44%] of 25 vs two [7%] of 30; p=0·028), bowel or bladder dysfunction (14 [56%] of 25 vs seven [23%] of 30; p=0·040), cardiovascular instability (nine [36%] of 25 vs one [3%] of 30; p=0·028), and were more likely to require intensive care unit admission (13 [52%] of 25 vs 5 [17%] of 30; p=0·028). On MRI, most children who were enterovirus positive showed brainstem pontine lesions (14 [61%] of 23), while other MRI parameters did not correlate with enterovirus status. Median EDSS of enterovirus positive (EV+) and enterovirus negative (EV-) groups was significantly different at all timepoints: baseline (EDSS 8·5, IQR 4·1-9·5 vs EDSS 4·0, IQR 3·0-6·0; p=0·0067), 3 months (EDSS 4·0, IQR 3·0-7·4 vs EDSS 3·0, IQR 1·5-4·3; p=0·0067), 6 months (EDSS 3·5, IQR 3·0-7·0 vs EDSS 3·0, IQR 1·0-4·0; p=0·029), and 12 months (EDSS 3·0, IQR 3·0-6·9 vs EDSS 2·5 IQR 0·3-3·0; p=0·0067). Kaplan-Meier survival analysis of a subgroup of patients showed significantly poorer motor recovery among children who tested positive for enterovirus than for those who tested negative (p=0·037).

INTERPRETATION

Detection of enterovirus in specimens from non-sterile sites at presentation correlated with more severe acute motor weakness, worse overall outcomes and poorer trajectory for motor recovery. These results have implications for rehabilitation planning as well as counselling of families of children with these disorders. The findings of this study support the need for early testing for enterovirus in non-CNS sites in all cases of AFM.

FUNDING

None.

The Utilization of Nerve Transfer for Reestablishing Shoulder Function in the Setting of Acute Flaccid Myelitis: A Single-Institution Review

BACKGROUND

Acute flaccid myelitis (AFM) is a rare disease of young children. The typical presentation involves acute-onset flaccid paralysis in one or more extremities with a nonspecific viral prodrome. Long-term outcomes demonstrate that functional recovery plateaus around six to nine months. The purpose of this study was to evaluate the efficacy of nerve transfers for restoring shoulder function in these patients.

METHODS

A retrospective review of all patients diagnosed with AFM at a single institution. Shoulder function was evaluated using the active movement scale (AMS). Children at a minimum of six months after diagnosis with plateaued shoulder AMS scores of 4 or less were indicated for surgery.

RESULTS

Eleven patients were identified with a mean time from symptom onset to surgery of 12 months. Average follow-up was 19 months. The mean AMS score at follow-up for shoulder external rotation and abduction was 4.6 and 2.8, respectively. A total of six different nerve transfers with five different donor nerves were used individually or in conjunction with each other. The most common transfers were from the spinal accessory nerve to the suprascapular nerve (n = 8) and from the intercostal nerves ×3 to the axillary nerve (n = 5). Patients who received a transfer from the radial nerve to the axillary nerve (n = 2) had the best functional returns, with the mean AMS score of 6.5 in both external rotation and abduction at follow-up.

CONCLUSION

Nerve transfer procedures may help restore shoulder function in the setting of AFM. Combination procedures that involve a transfer from the radial nerve to the axillary nerve may provide the best functional results.

Acute Neuromuscular Disorders in the Pediatric Intensive Care Unit

BACKGROUND

The neuromuscular disorders encountered in the pediatric intensive care unit (PICU) encompass a broad spectrum of pathologies. These include acute disorders (eg, Guillain-Barre syndrome), acute-on-chronic disorders (eg, myasthenia gravis), progressive disorders (eg, muscular dystrophy), and disorders that develop in the PICU (eg, critical illness myopathy/polyneuropathy). Familiarity with the presenting features of these disorders is of paramount importance in facilitating timely diagnosis.

METHODS

We conducted a retrospective review of the medical records of patients admitted to the PICU or Intermediate Care Program (ICP) at a single tertiary children's hospital from 2006 to 2017 with an acute or acute-on-chronic neuromuscular disorder. We did not include patients with a known progressive neuromuscular disorder or critical illness myopathy/polyneuropathy.

RESULTS

Twenty-four patients were admitted to the PICU/ICP with acute or acute-on-chronic neuromuscular disorders. Diagnosis and indication for ICU/ICP admission were Guillain-Barre syndrome (n = 6; respiratory failure: 3, respiratory monitoring: 2, autonomic instability: 1), myasthenia gravis (n = 5; airway clearance: 3, respiratory failure: 2), acute flaccid myelitis (n = 3; respiratory failure: 2, respiratory monitoring: 1), periodic paralysis (n = 3; intravenous potassium replacement), rhabdomyolysis (n = 3; monitoring for electrolyte derangements), infant botulism (n = 2; respiratory failure), chronic demyelinating polyneuropathy (n = 1; respiratory failure), and congenital myasthenic syndrome (n = 1; apnea). No patients were admitted to the PICU/ICP with a diagnosis of tick paralysis, acute intermittent porphyria, or inflammatory myopathy.

CONCLUSIONS

Although acute and acute-on-chronic neuromuscular disorders are encountered relatively rarely in the PICU, familiarity with the presenting features of these disorders is important in facilitating timely diagnosis. This, in turn, enables the institution of effective management strategies, thereby avoiding complications associated with diagnostic delays.

Acute Flaccid Myelitis: Characteristics and Outcomes of 2014 and 2016 Cases at a Single Center

Acute flaccid myelitis (AFM) is a rare condition associated with spinal cord gray matter abnormalities and frequent persistent motor deficits in the limbs. We present our experience with the diagnosis, management, and outcomes of affected children in 2014 and 2016, emphasizing features that should trigger early consideration of AFM. Early viral testing may increase the rate of detecting associated viruses.

Early use of an implantable diaphragm pacing stimulator for a child with severe acute flaccid myelitis-a case report

Introduction

Acute Flaccid Myelitis (AFM) is a recently recognized, polio-like illness of children that can be functionally devastating. Severe cases can lead to ventilatory failure. Incomplete phrenic nerve injuries in other populations has been shown to respond to diaphragmatic stimulation. We therefore proposed an early assessment for incomplete denervation by laparoscopic direct stimulation of the diaphragm and placement of a diaphragmatic pacing system to enhance diaphragm function.

Case presentation

A 3 year-old girl presented with AFM with clinically and electrodiagnostically severe involvement of all four limbs and muscles of respiration. Direct stimulation of the diaphragm demonstrated contraction and a diaphragmatic stimulator was placed at 3 weeks post presentation. The patient was immediately able to tolerate short bouts of reduced ventilation settings. Electromyography via the pacing wires demonstrated intact motor units consistent with partial denervation/reinnervation in the left hemidiaphragm, and no motor units in the right hemidiaphragm. At three months, she tolerated 6 h of pacing on pressure support setting. At 5 months she demonstrated larger tidal volumes with active pacing than without.

Discussion

In our experience, AFM patients who require chronic ventilator support are rarely able to be weaned. Despite clinical and surface electrodiagnostic evidence of complete phrenic nerve involvement, the patient's diaphragm responded to direct stimulation. The patient preferred pacing over non-pacing times and showed improved ventilatory ability with pacing as opposed to without, though remains ventilator-dependent. These findings support augmentation of diaphragm function and possible enhanced recovery of spontaneous function.

Clinical Subpopulations in a Sample of North American Children Diagnosed With Acute Flaccid Myelitis, 2012-2016

IMPORTANCE

Acute flaccid myelitis (AFM) is an emerging poliolike illness of children whose clinical spectrum and associated pathogens are only partially described. The case definition is intentionally encompassing for epidemiologic surveillance to capture all potential AFM cases. Defining a restrictive, homogenous subpopulation may aid our understanding of this emerging disease.

OBJECTIVE

To evaluate the extent to which the US Centers for Disease Control and Prevention (CDC) case definition of AFM incorporates possible alternative diagnoses and to assess the plausibility of a case definition that enriches the biological homogeneity of AFM for inclusion in research studies.

DESIGN, SETTING, AND PARTICIPANTS

Retrospective case analysis of children younger than 18 years diagnosed as having AFM between 2012 and 2016 using the CDC case definition. Group 1 included patients recruited from the United States and Canada based on the CDC case definition of AFM. Group 2 included patients referred to the Johns Hopkins Transverse Myelitis Center for evaluation of suspected AFM. Patients' records and imaging data were critically reviewed by 3 neurologists to identify those cases with definable alternative diagnoses, and the remaining patients were categorized as having restrictively defined AFM (rAFM). Clinical characteristics were compared between patients with rAFM (cases) and those with alternative diagnoses, and a case description distinguishing these AFM groups was identified. Interrater reliability of this description was confirmed for a subset of cases by a fourth neurologist. Data were analyzed between May 2017 and November 2018.

MAIN OUTCOMES AND MEASURES

Proportion of patients with possible alternative diagnosis.

RESULTS

Of the 45 patients who met the CDC AFM case definition and were included, the mean age was 6.1 years; 27 were boys (60%); and 37 were white (82%), 3 were Asian (7%), 1 was Hispanic (2%), and 4 were mixed race/ethnicity (9%). Of the included patients, 34 were classified as having rAFM, and 11 had alternate diagnoses (including transverse myelitis, other demyelinating syndromes, spinal cord stroke, Guillain-Barre syndrome, Chiari I myelopathy, and meningitis). Factors differing between groups were primarily asymmetry of weakness, lower motor neuron signs, preceding viral syndrome, symptoms evolving over hours to days, absence of sensory deficits, and magnetic resonance imaging findings. A case description was able to reliably define the rAFM group.

CONCLUSIONS AND RELEVANCE

We present an approach for defining a homogeneous research population that may more accurately reflect the pathogenesis of the prototypical poliomyelitis-like subgroup of AFM. The definition of rAFM forms a blueprint for inclusion criteria in future research efforts, but more work is required for refinement and external validation.

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.