Neurologic complications of 2009 influenza-a H1N1 infection in children

COVID-19 and Acute Neurologic Complications in Children

BACKGROUND

Little is known about the epidemiology and outcomes of neurologic complications associated with coronavirus disease 2019 (COVID-19) in children.

METHODS

We performed a cross-sectional study of children 2 months to <18 years of age with COVID-19 discharged from 52 children's hospitals from March 2020 to March 2022. Neurologic complications were defined as encephalopathy, encephalitis, aseptic meningitis, febrile seizure, nonfebrile seizure, brain abscess and bacterial meningitis, Reye's syndrome, and cerebral infarction. We assessed length of stay (LOS), ICU admission, 30 day readmissions, deaths, and hospital costs. We used multivariable logistic regression to identify factors associated with neurologic complications.

RESULTS

Of 15 137 children hospitalized with COVID-19, 1060 (7.0%) had a concurrent diagnosis of a neurologic complication. The most frequent neurologic complications were febrile seizures (3.9%), nonfebrile seizures (2.3%), and encephalopathy (2.2%). Hospital LOS, ICU admission, ICU LOS, 30 day readmissions, deaths, and hospital costs were higher in children with neurologic complications compared with those without complications. Factors associated with lower odds of neurologic complications included: younger age (adjusted odds ratio [aOR]: 0.97; 95% confidence interval [CI]: 0.96-0.98), occurrence during delta variant predominant time period (aOR: 0.71; 95% CI: 0.57-0.87), presence of a nonneurologic complex chronic condition (aOR: 0.80; 95% CI: 0.69-0.94). The presence of a neurologic complex chronic condition was associated with higher odds of neurologic complication (aOR 4.14, 95% CI 3.48-4.92).

CONCLUSIONS

Neurologic complications are common in children hospitalized with COVID-19 and are associated with worse hospital outcomes. Our findings emphasize the importance of COVID-19 immunization in children, especially in high-risk populations, such as those with neurologic comorbidity.

Outcomes in influenza and RANBP2 mutation-associated acute necrotizing encephalopathy of childhood

AIM

To evaluate clinical and imaging features in patients with acute necrotizing encephalopathy of childhood (ANEC) to identify predictors of RANBP2 mutations, influenza association, and long-term outcomes.

METHOD

A retrospective chart review in patients with ANEC (2012-2020) seen at a tertiary pediatric center was performed. Children were included if they had acute inflammatory lesions in the basal ganglia and pons. Variables included presenting features, imaging characteristics, RANBP2 gene testing, nasopharyngeal swab findings, therapies, and long-term outcomes.

RESULTS

Twenty patients were included (average age at presentation 3y 6mo, interquartile range  3y 7mo, SD  2y 8mo; 14 females, six males). Three of the 20 experienced recurrences; one of the 20 died. Ten patients were influenza positive. Seven patients were RANBP2 mutation positive. A higher likelihood of hemorrhage was observed in patients who were influenza positive compared to influenza negative (p=0.048). Patients with influenza had a higher degree of thalamic hemorrhage (2, p=0.035) and greater extent of diffusion restriction (3, p=0.035) in semiquantitive analysis.

INTERPRETATION

Children with ANEC who are positive for influenza are more likely to have hemorrhage and greater thalamic swelling. RANBP2 status was predictive of relapse but not predictive of overall outcome.

Ictogenesis of viral pneumonia: A comparison between SARS-CoV-2 and H1N1/H3N2

Several studies reported acute symptomatic seizures as a possible neurological complication of COVID-19 pneumonia. Apart from metabolic imbalances, hypoxia, and fever, other ictogenic mechanisms are likely related to an immune-mediated damage. The same mechanisms are shared by other respiratory viruses. Since neurotropic properties of SARS-CoV-2 have been questioned, we investigated whether SARS-CoV-2 has a similar ictogenic potential to other respiratory non-neurotropic viruses. We conducted a retrospective study identifying 1141 patients with SARS-CoV-2 pneumonia and 146 patients with H1N1/H3N2 pneumonia. We found a similar prevalence of seizures in the two viral pneumonia (1.05% with SARS-CoV-2 vs 2.05% with influenza; p = 0.26). We detailed clinical, electroencephalographic, and neuroradiological features of each patient, together with the hypothesized pathogenesis of seizures. Previous epilepsy or pre-existing predisposing conditions (i.e., Alzheimer's disease, stroke, cerebral neoplasia) were found in one-third of patients that experienced seizures, while two-thirds of patients had seizures without known risk factors other than pneumonia in both groups. The prevalence of pre-existing predisposing conditions and disease severity indexes was similar in SARS-CoV-2 and H1N1/H3N2 pneumonia, thus excluding they could act as potential confounders. Considering all the patients with viral pneumonia together, previous epilepsy (p < 0.001) and the need for ventilatory support (p < 0.001), but not the presence of pre-existing predisposing conditions (p = 0.290), were associated with seizure risk. Our study showed that SARS-CoV-2 and influenza viruses share a similar ictogenic potential. In both these infections, seizures are rare but serious events, and can manifest without pre-existing predisposing conditions, in particular when pneumonia is severe, thus suggesting an interplay between disease severity and host response as a major mechanism of ictogenesis, rather than a virus-specific mechanism.

Prevalence, Risk Factors, and Outcomes of Influenza-Associated Neurologic Complications in Children

OBJECTIVE

To determine the frequency of neurologic complications associated with influenza in hospitalized children.

STUD DESIGN

We performed a cross-sectional study of children (2 months through 17 years of age) with influenza discharged from 49 children's hospitals in the Pediatric Health Information System during the influenza seasons of 2015-2020. Neurologic complications were defined as encephalopathy, encephalitis, aseptic meningitis, febrile seizure, nonfebrile seizure, brain abscess and bacterial meningitis, Reye syndrome, and cerebral infarction. We assessed length of stay (LOS), intensive care unit (ICU) admission, ICU LOS, 30-day hospital readmissions, deaths, and hospital costs associated with these events. Patient-level risk factors associated with neurologic complications were identified using multivariable logistic regression.

RESULTS

Of 29 676 children hospitalized with influenza, 2246 (7.6%) had a concurrent diagnosis of a neurologic complication; the most frequent were febrile seizures (5.0%), encephalopathy (1.7%), and nonfebrile seizures (1.2%). Hospital LOS, ICU admission, ICU LOS, deaths, and hospital costs were greater in children with neurologic complications compared with those without complications. Risk factors associated with neurologic complications included male sex (aOR 1.1, 95% CI 1.02-1.21), Asian race/ethnicity (aOR 1.7, 95% CI 1.4-2.1) (compared with non-Hispanic White), and the presence of a chronic neurologic condition (aOR 3.7, 95% CI 3.1-4.2).

CONCLUSIONS

Neurologic complications are common in children hospitalized with influenza, especially among those with chronic neurologic conditions, and are associated with worse outcomes compared with children without neurologic complications. These findings emphasize the strategic importance of influenza immunization and treatment, especially in high-risk populations.

Influenza-Associated Acute Necrotizing Encephalopathy in Siblings

Encephalopathy is an important complication associated with influenza, most frequently observed in young children, with a wide range of severity. The most severe category of influenza-associated encephalopathy (IAE) is acute necrotizing encephalopathy (ANE), characterized by high frequency of neurologic sequelae and fatal outcomes. We report two young siblings who developed fever and seizures with altered mental status. Influenza A(H1N1)pdm09 virus infection was identified in upper respiratory tract specimens from both patients, and neuroimaging revealed bilateral inflammatory lesions, consistent with acute necrotizing encephalopathy. Neither child had received influenza vaccination. Both children progressed to critical illness and required invasive mechanical ventilation. In addition to critical care management, both patients received high-dose corticosteroids, mannitol, anticonvulsants, and antiviral treatment of influenza. The older child recovered fully and was discharged 2 weeks after illness onset, but the younger sibling developed severe brainstem edema and cerebellar tonsillar herniation, and died on illness day 11. Both children tested positive for Ran Binding Protein 2 (RANBP2) gene mutations. RANBP2 is a genetic polymorphism associated with recurrent episodes of necrotizing encephalitis with respiratory viral infections. Annual influenza vaccination is especially important for ANE survivors, with or without RANBP2 mutations, their household contacts, and caregivers. During influenza season, close monitoring of any child with a history of neurological complications associated with respiratory illness is indicated, with prompt initiation of antiviral treatment with onset of acute respiratory illness, and influenza testing performed by molecular assay.

Epilepsy in Children After Pandemic Influenza Vaccination

OBJECTIVES

To determine if pandemic influenza vaccination was associated with an increased risk of epilepsy in children.

METHODS

Information from Norwegian registries from 2006 through 2014 on all children <18 years living in Norway on October 1, 2009 was used in Cox regression models to estimate hazard ratios for incident epilepsy after vaccination. A self-controlled case series analysis was used to estimate incidence rate ratios in defined risk periods after pandemic vaccination.

RESULTS

In Norway, the main period of the influenza A subtype H1N1 pandemic was from October 2009 to December 2009. On October 1, 2009, 1 154 113 children <18 years of age were registered as residents in Norway. Of these, 572 875 (50.7%) were vaccinated against pandemic influenza. From October 2009 through 2014 there were 3628 new cases of epilepsy (incidence rate 6.09 per 10 000 person-years). The risk of epilepsy was not increased after vaccination: hazard ratio: 1.07; 95% confidence interval: 0.94-1.23. Results from the self-controlled case series analysis supported the finding of no association between vaccination and subsequent epilepsy.

CONCLUSIONS

Pandemic influenza vaccination was not associated with increased risk of epilepsy. Concerns about pandemic vaccination causing epilepsy in children seem to be unwarranted.

Focal Encephalitis, Meningitis, and Acute Respiratory Distress Syndrome Associated with Influenza A Infection

OBJECTIVE

To present a case of influenza A infection complicated with focal encephalitis, meningitis, and acute respiratory distress syndrome.

CLINICAL PRESENTATION AND INTERVENTION

A 35-year-old woman presented with fever, headache, cough, and body aches. Seizures, altered consciousness, and dyspnea occurred later. A nasopharyngeal swab revealed a positive reaction for the influenza A antigen. Magnetic resonance imaging scans showed a T2 prolongation in the left frontoparietal subcortical white matter, which was consistent with focal encephalitis. She recovered after treatment with oseltamivir and antibiotics.

CONCLUSION

This case report highlights focal encephalitis with concomitant pulmonary complications after influenza A infection.

Neurological Complications of Respiratory Disease

The respiratory and central nervous systems are intimately connected. Ventilatory control is strictly regulated by central mechanisms in a complex process that involves central and peripheral chemoreceptors, baroreceptors, the cardiovascular system, and specific areas of the brain responsible for autonomic control. Disorders of the lung and respiratory system can interfere with these mechanisms and temporarily or permanently disrupt this complex network resulting in mild to severe neurological sequelae. This article explores the wide variety of neurological problems resulting from respiratory dysfunction, with emphasis on its pathophysiology, clinical features, prognosis, and long-term outcome.

Neurology of the H1N1 pandemic in Singapore: a nationwide case series of children and adults

Neurologic complications have long been associated with influenza. A novel strain of influenza A (H1N1) first described in humans to have outbreak potential in 2009 in Mexico went on to become the first influenza pandemic of this century. We evaluated the neurologic complications of the novel influenza A (H1N1) 2009 in children and adults admitted to all public hospitals in Singapore during the influenza A (H1N1) 2009 pandemic between May 2009 and March 2010. All patients were positive for novel H1N1 infection and presented with neurologic symptoms prior to oseltamivir treatment. Ninety-eight patients (median age 6.6 years, range 0.4-62.6) were identified; 90 % were younger than 18 years; 32 % suffered from preexisting neurological, respiratory, or cardiac disease; and 66 % presented with seizures. Of those presenting with seizures, new onset seizures were the most common manifestation (n = 40, 61.5 %), followed by breakthrough seizures (n = 18, 27.7 %) and status epilepticus (n = 7, 10.8 %). Influenza-associated encephalopathy occurred in 20 %. The majority of children (n = 88) presented with seizures (n = 63, 71.6 %), encephalopathy (n = 19, 21.6 %), and syncope (n = 4, 4.5 %). Among adults, a wider range of neurological conditions were seen, with half of them presenting with an exacerbation of their underlying neurological disease. The neurological symptoms developed at a median of 2 days after the onset of systemic symptoms. The median length of hospital stay was 3 days, and 79 % were monitored in general wards. Neurologic complications associated with the novel influenza A (H1N1) 2009 strain were generally mild and had a good outcome. They occurred more frequently in patients with underlying neurological disorders. Seizures and encephalopathy were the most common manifestations, similar to other influenza virus strains.

Neurological events related to influenza A (H1N1) pdm09

OBJECTIVES

To review neurological complications after the influenza A (H1N1) pdm09, highlighting the clinical differences between patients with post-vaccine or viral infection.

DESIGN

A search on Medline, Ovid, EMBASE, and PubMed databases using the keywords “neurological complications of Influenza AH1N1” or “post-vaccine Influenza AH1N1.”

SETTING

Only papers written in English, Spanish, German, French, Portuguese, and Italian published from March 2009 to December 2012 were included.

SAMPLE

We included 104 articles presenting a total of 1636 patient cases. In addition, two cases of influenza vaccine-related neurological events from our neurological care center, arising during the period of study, were also included.

MAIN OUTCOME MEASURES

Demographic data and clinical diagnosis of neurological complications and outcomes: death, neurological sequelae or recovery after influenza A (H1N1) pdm09 vaccine or infection.

RESULTS

The retrieved cases were divided into two groups: the postvaccination group, with 287 patients, and the viral infection group, with 1349 patients. Most patients in the first group were adults. The main neurological complications were Guillain-Barre syndrome (GBS) or polyneuropathy (125), and seizures (23). All patients survived. Pediatric patients were predominant in the viral infection group. In this group, 60 patients (4.7%) died and 52 (30.1%) developed permanent sequelae. A wide spectrum of neurological complications was observed.

CONCLUSIONS

Fatal cases and severe, permanent, neurological sequelae were observed in the infection group only. Clinical outcome was more favorable in the post-vaccination group. In this context, the relevance of an accurate neurological evaluation is demonstrated for all suspicious cases, as well as the need of an appropriate long-term clinical and imaging follow-up of infection and post-vaccination events related to influenza A (H1N1) pdm09, to clearly estimate the magnitude of neurological complications leading to permanent disability.

Efficacy of intravenous immunoglobulin treatment in immunocompromised children with H1N1 influenza: a clinical observation

BACKGROUND AND AIMS

The appropriate treatment of pandemic H1N1 influenza which was first identified in April 2009 in Mexico is insufficient especially for immunocompromised patients. We aimed to evaluate the features and prognostic factors of the children with H1N1, especially immunocompromised ones, and whether intravenous immunoglobulin G (IVIG) replacement could aid for a better outcome.

METHODS

Twenty-one hospitalized children with laboratory-confirmed H1N1 were evaluated retrospectively. Data were extracted from files and electronic medical records.

RESULTS

The median age was 37 (1-216) months; 62% of them were under 5 years of age and 71.4% had one or more underlying disorders. Main symptoms were high fever, cough, fatigue and vomiting. Lower respiratory tract manifestations were seen in 66.6% of children. Mortality rate was 4.7%. The patient who died had the lowest lymphocyte (100/mm(3) ), thrombocyte (21 000/mm(3) ) and highest blood urea nitrogen (87 mg/dL) levels. Fifty-eight percent of evaluated patients had one of the primary immunodeficiency disorders. Surprisingly, none of the six patients with primary immunodeficiency who are on regular IVIG replacement needed intensive care unit and died. Although median durations of cough, fever and hospitalization were lower, they did not change statistically according to get IVIG replacement regularly (P = 0.47, 0.97, 0.09, respectively).

CONCLUSION

Our study is important while it is the first one that shows the course of primary immunodeficient children with H1N1 infection who were on regular IVIG replacement. A trial of high-dose IVIG may be a useful adjunctive therapy in severe H1N1 influenza, particularly in the immunocompromised patients.

Neurological manifestations of influenza infection in children and adults: results of a National British Surveillance Study

BACKGROUND

The emergence of influenza A(H1N1) 2009 was met with increased reports of associated neurological manifestations. We aimed to describe neurological manifestations of influenza in adults and children in the United Kingdom that presented at this time.

METHODS

A 2-year surveillance study was undertaken through the British adult and pediatric neurological surveillance units from February 2011. Patients were included if they met clinical case definitions within 1 month of proven influenza infection.

RESULTS

Twenty-five cases were identified: 21 (84%) in children and 4 (16%) in adults. Six (29%) children had preexisting neurological disorders. Polymerase chain reaction of respiratory secretions identified influenza A in 21 (81%; 20 of which [95%] were H1N1) and influenza B in 4 (15%). Twelve children had encephalopathy (1 with movement disorder), 8 had encephalitis, and 1 had meningoencephalitis. Two adults had encephalopathy with movement disorder, 1 had encephalitis, and 1 had Guillain-Barré syndrome. Seven individuals (6 children) had specific acute encephalopathy syndromes (4 acute necrotizing encephalopathy, 1 acute infantile encephalopathy predominantly affecting the frontal lobes, 1 hemorrhagic shock and encephalopathy, 1 acute hemorrhagic leukoencephalopathy). Twenty (80%) required intensive care, 17 (68%) had poor outcome, and 4 (16%) died.

CONCLUSIONS

This surveillance study described a cohort of adults and children with neurological manifestations of influenza. The majority were due to H1N1. More children than adults were identified; many children had specific encephalopathy syndromes with poor outcomes. None had been vaccinated, although 8 (32%) had indications for this. A modified classification system is proposed based on our data and the increasing spectrum of recognized acute encephalopathy syndromes.

Complications and associated bacterial coinfections among children hospitalized with seasonal or pandemic influenza, United States, 2003-2010

BACKGROUND

Data on the range and severity of influenza-associated complications among children are limited. We describe the frequency and severity of complications in hospitalized children aged <18 years with seasonal influenza (during 2003-2009) and 2009 pandemic influenza A(H1N1) (during 2009-2010).

METHODS

Population-based surveillance for laboratory-confirmed influenza hospitalizations was conducted among 5.3 million children in 10 states. Complications were identified by International Classification of Diseases, Ninth Revision (ICD-9) codes in medical records.

RESULTS

During 2003-2010, 7293 children hospitalized with influenza were identified, of whom 6769 (93%) had complete ICD-9 code data. Among the 6769 children, the median length of hospitalization was 3 days (interquartile range, 2-4 days), 975 (14%) required intensive care, 359 (5%) had respiratory failure, and 40 (1%) died. The most common complications were pneumonia (in 28% of children), asthma exacerbations (in 22% [793/3616] aged ≥ 2 years), and dehydration (in 21%). Lung abscess/empyema, tracheitis, encephalopathy, bacteremia/sepsis, acute renal failure, and myocarditis were rare (each ≤ 2% of children) but associated with a median hospitalization duration of ≥ 6 days, and 48%-70% of children required intensive care. Bacterial cultures with positive results were identified in 2% of children (107/6769); Staphylococcus aureus and Streptococcus pneumoniae were most commonly identified.

CONCLUSIONS

Complications contribute substantially to the disease burden among children hospitalized with influenza, through intensive care requirements and prolonged hospitalization, highlighting the importance of primary prevention with influenza vaccination.