Influenza A encephalitis with movement disorder

Movement disorders associated with pediatric encephalitis

New onset movement disorders are a common clinical problem in pediatric neurology and can be infectious, inflammatory, metabolic, or functional in origin. Encephalitis is one of the more important causes of new onset movement disorders, and movement disorders are a common feature (~25%) of all encephalitis. However, all encephalitides are not the same, and movement disorders are a key diagnostic feature that can help the clinician identify the etiology of the encephalitis, and therefore appropriate treatment is required. Movement disorders are a characteristic feature of autoimmune encephalitis such as anti-NMDAR encephalitis, herpes simplex virus encephalitis-induced autoimmune encephalitis, and basal ganglia encephalitis. Other rarer autoantibody-associated encephalitis syndromes with movement disorder associations include encephalitis associated with glycine receptor, DPPX, and neurexin-3 alpha autoantibodies. In addition, movement disorders can accompany acute disseminated encephalomyelitis with and without myelin oligodendrocyte glycoprotein antibodies. Extremely important infectious encephalitides that have characteristic movement disorder associations include Japanese encephalitis, dengue fever, West Nile virus, subacute sclerosing panencephalitis (SSPE), and SARS-CoV-2 (COVID-19). This chapter discusses how specific movement disorder phenomenology can aid clinician diagnostic suspicion, such as stereotypy, perseveration, and catatonia in anti-NMDAR encephalitis, dystonia-Parkinsonism in basal ganglia encephalitis, and myoclonus in SSPE. In addition, the chapter discusses how the age of the patients can influence the movement disorder phenomenology, such as in anti-NMDAR encephalitis where chorea is typical in young children, even though catatonia and akinesia is more common in adolescents and adults.

Bibliometric analysis of publication trends and topics of influenza-related encephalopathy from 2000 to 2022

BACKGROUND

Influenza-related encephalopathy is a rapidly progressive encephalopathy that usually presents during the early phase of influenza infection and primarily manifests as central nervous system dysfunction. This study aimed to analyze the current research status and hotspots of influenza-related encephalopathy since 2000 through bibliometrics analysis.

METHODS

The Web of Science Core Collection (WOSCC) was used to extract global papers on influenza-related encephalopathy from 2000 to 2022. Meanwhile, the VOSviewer and CiteSpace software were used for data processing and result visualization.

RESULTS

A total of 561 published articles were included in the study. Japan was the country that published the most articles, with 205 articles, followed by the United States and China. Okayama University and Tokyo Medical University published the most articles, followed by Nagoya University, Tokyo University, and Juntendo University. Based on the analysis of keywords, four clusters with different research directions were identified: "Prevalence of H1N1 virus and the occurrence of neurological complications in different age groups," "mechanism of brain and central nervous system response after influenza virus infection," "various acute encephalopathy" and "diagnostic indicators of influenza-related encephalopathy."

CONCLUSIONS

The research progress, hotspots, and frontiers on influenza-related encephalopathy after 2000 were described through the visualization of bibliometrics. The findings will lay the groundwork for future studies and provide a reference for influenza-related encephalopathy. Research on influenza-related encephalopathy is basically at a stable stage, and the number of research results is related to outbreaks of the influenza virus.

Acute Movement Disorders in Childhood

Acute-onset movement disorders (MDs) are an increasingly recognized neurological emergency in both adults and children. The spectrum of possible causes is wide, and diagnostic work-up is challenging. In their acute presentation, MDs may represent the prominent symptom or an important diagnostic clue in a broader constellation of neurological and extraneurological signs. The diagnostic approach relies on the definition of the overall clinical syndrome and on the recognition of the prominent MD phenomenology. The recognition of the underlying disorder is crucial since many causes are treatable. In this review, we summarize common and uncommon causes of acute-onset movement disorders, focusing on clinical presentation and appropriate diagnostic investigations. Both acquired (immune-mediated, infectious, vascular, toxic, metabolic) and genetic disorders causing acute MDs are reviewed, in order to provide a useful clinician’s guide to this expanding field of pediatric neurology.

Covid-19: Involvement of the nervous system. Identifying neurological predictors defining the course of the disease

The main objective of this study was to analyse neurological symptoms during a Covid-19 infection and determine the pattern of symptoms by comparing outpatients with inpatients. A further goal was to identify possible predictors, such as pre-existing conditions and neurological symptoms.

We recorded the clinical data of 40 inpatients and 42 outpatients in this retrospective, cross sectional study. Of them, 68 patients (83%), evenly distributed between the two groups, suffered from neurological symptoms. We identified the onset of neurological symptoms and the related time ranges in 41 patients (36 outpatients and 5 inpatients). Of these, 63.4% reported neurological symptoms on the first or second day of illness. 49 patients (72%) showed combinations of at least two to a maximum of seven different neurological symptoms. A more severe course of disease was correlated with age and male sex, but age was not identified as a predictor for the occurrence of neurological symptoms. Women suffered from central and neuromuscular symptoms more often than men (p = 0,004). The most common symptoms were fatigue (54%), headache (31%), loss of taste (31%), and loss of smell (27%).

Pre-existing dementia was associated with increased lethality; similarly, pre-existing stroke was associated with a more severe course of Covid-19 infection. Hallucinations and confusion were related to an increased likelihood of death.

The present data demonstrate the importance of comprehensive neurological support of inpatients and outpatients affected by Covid-19.

Transient Generalized Chorea in Influenza A Encephalopathy

Background

Influenza A infections are a rare cause of movement disorders. Previously described patients have suffered from acute-onset myoclonus and/or dystonia or post-viral parkinsonism.

Case Report

We present the case of a 74-year-old female patient with transient generalized chorea due to influenza A-mediated encephalopathy.

Discussion

We discuss whether the clinical presentation and the magnetic resonance imaging changes may be attributable to cytokine-mediated encephalopathy or to direct cytotoxic effects of the virus. Additionally, we would like to make clinicians aware of this clinical sign in the context of viral encephalopathy.

Acute Hemichorea Can Be the Only Clinical Manifestation of Post-Varicella Vasculopathy: Two Pediatric Clinical Cases

Acute hemichorea can occur in the context of infectious, autoimmune, metabolic, toxic, and vascular neuropathologies. Primary infection by varicella zoster virus (VZV) can result in vasculopathy with neurological manifestations, such as hemiparesis, at times accompanied by hemichorea. Isolated hemichorea, however, had not been reported. We here describe two cases of VZV-induced vasculopathy whose sole clinical manifestation was acute hemichorea. Both cases involved young boys of 3 years of age, who presented with acute hemichorea 4–6 months after initial VZV infection. All hematological, immunological, and toxicological tests were normal, except for the presence of VZV IgG. Brain structural magnetic resonance imaging (MRI) and magnetic resonance angiography revealed specific signs of vasculitis and ischemic lesions in the basal ganglia region (lentiform nucleus, thalamus, and internal capsule). Following corticosteroid and acetylsalicylic acid treatment, full symptomatic recovery was achieved within 3 weeks. Repeated MRI documented full neurostructural recovery, which was confirmed at extended follow-up for more than 1 year. These cases indicate that VZV-induced vasculopathy should be considered in the case of pediatric isolated acute hemichorea.

Movement disorders of probable infectious origin

Background:

Movement disorders (MDs) associated with infections remains an important debilitating disorder in the Asian countries.

Objectives:

The objective of the following study is to report the clinical and imaging profile of a large cohort of patients with MDs probably associated with infection.

Materials and Methods:

This was a chart review of 35 patients (F:M-15:20) presenting with MD in the Neurology services of National Institute of Mental Health and Neurosciences, India. The demographic profile, type of infection, time from infection to MD, phenomenology of MD and magnetic resonance imaging (MRI) findings were reviewed.

Results:

The mean age at presentation was 22.6 ± 13.3 years, (5-60), age of onset of MD was 15.7 ± 15 years, and duration of symptoms was 6.9 ± 8.1 years (42 days to 32 years). The mean latency of onset of MD after the infection was 5.9 ± 4.2 weeks. The phenomenology of MD were: (1) Pure dystonia-28.6%, (2) dystonia with choreoathetosis-22.9%, (3) Parkinsonism-14.6%, (4) pure tremor, hemiballismus, myoclonus and chorea-2.9% each, and (5) mixed MD-22.9%. Most often the MD was generalized (60%), followed by right upper limb (31.4%) and left upper limb (8.6%). A viral encephalitic type of neuroinfection was the most common infection (85.7%), which was associated with MD. Abnormalities of brain MRI, seen in 79.2%, included signal changes in (1) thalamus-52.0%, (2) putamen and subcortical white matter-16% each, (3) pons-12%, (4) striatopallidum, striatum and grey matter-8% each, and (5) caudate, cerebellum, lentiform nucleus, midbrain and subthalamic nucleus-4.0% each.

Conclusions:

MDs associated with infection were the most often post-encephalitic. Dystonia was the most common MD, and thalamus was the most common anatomical site involved.

Neurologic aspects of influenza viruses

Although influenza A and B viruses are primarily known as respiratory viruses and mainly infected only the upper respiratory tract in humans, patients with influenza often develop signs and symptoms that are not due to the respiratory system. Frequently individuals with influenza develop headaches, meningismus, and even seizures in addition to their typical respiratory symptoms. In the past decades, influenza viruses have also been associated with serious non-respiratory signs. The famous 1918 strain of influenza was associated with von Economo's encephalitis lethargica and postencephalitic parkinsonism. In the 1960s influenza virus infections in children were associated with Reye's syndrome characterized often by fatty non-inflammatory hepatic disease and an encephalopathy with marked non-inflammatory cerebral edema. Intermittently children with influenza develop focal myalgia and myositis. Guillain–Barré syndrome was epidemiologically associated with the 1978 killed influenza vaccine but not subsequent vaccines. Although occasional children with influenza have developed encephalopathy, from 2000 through 2004 there was an increase in the number of serious cases of acute necrotizing encephalopathy accompanying infection with the influenza A 2009 strain. The current H5N1 strain of bird influenza occasionally infects humans with a high mortality rate and some appear to have central nervous signs. This chapter explores what is known about these influenza neurologic associations.

Secondary paroxysmal dyskinesia associated with 2009 H1N1 infection

Neurological complications associated with 2009 H1N1 infection in children have been reported and recognized worldwide. The most commonly reported neurological complications are seizures and encephalopathy. Secondary movement disorders are also associated with the infection, but such cases are rarely reported. Here, we describe the case of a 14-year-old boy with paroxysmal kinesigenic dyskinesia secondary to 2009 H1N1 infection, who presented with dystonia and choreic movement triggered by sudden voluntary movement.

Neurological complications of pandemic influenza A H1N1 2009 infection: European case series and review

Neurological manifestations and outcomes of children with the 2009 H1N1 virus infection have been reported in three American series and from smaller cohorts and case reports worldwide. Of the 83 children admitted between April 2009 and March 2010 with H1N1 virus infection to a tertiary children's hospital in a European setting, five children aged between 2 and 10 years had neurological symptoms. Four patients had seizures and encephalopathy at presentation. One patient presented with ataxia; one developed neuropsychiatric manifestations, and two developed movement disorders during the disease course. Early neuroimaging showed evidence of acute necrotising encephalopathy (ANE) in one case and non-specific white matter changes in another. Initial neuroimaging was normal for the other three, but interval MRI showed increased signal in bilateral periventricular distribution in one and significant cerebral volume loss in the other. Clinical outcomes varied: two recovered fully while three had residual seizures and/or significant cognitive deficits. Conclusion An analysis of our patients along with all reported cases reveal that seizures and encephalopathy were common neurological presentations associated with pandemic 2009 H1N1 influenza virus infection in children requiring hospital admission. Neuroimaging suggestive of ANE, basal ganglia involvement and volume loss appears to be associated with worse neurological outcome.

Neurological sequelae of 2009 influenza A (H1N1) in children: a case series observed during a pandemic

OBJECTIVE

To outline a series of cases demonstrating neurologic complications in children with Influenza infection. The ongoing 2009 influenza A (H1N1) presents significant challenges to the field of pediatric critical care and requires increased awareness of new presentations and sequelae of infection. Since World Health Organization declared a H1N1 pandemic, much attention has been focused on its respiratory manifestations of the illness, but limited information regarding neurologic complications has been reported.

DESIGN

Case series.

SETTING

Pediatric intensive care unit of a tertiary care medical facility.

PATIENTS

Four children admitted to the pediatric intensive care unit between March and November 2009 at the Children's Hospital of Pittsburgh with altered mental status and influenza infection.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The clinical course was extracted by chart review and is summarized. All children demonstrated a coryzal prodrome, fever, and altered level of consciousness at admission, and one child presented with clinical seizures. Diagnostic studies performed to establish a diagnosis are summarized. All children had abnormal electroencephalograms early in their intensive care unit course and 50% had abnormal imaging studies. All children survived but 50% had neurologic deficits at hospital discharge.

CONCLUSION

We conclude that 2009 influenza A (H1N1) can cause significant acute and residual neurologic sequelae. Clinicians should consider Influenza within a comprehensive differential diagnosis in children with unexplained mental status changes during periods of pandemic influenza.

Transient Bilateral Basal Ganglia Lesions in Rotavirus Encephalopathy

Rotavirus gastroenteritis may be associated with the onset of an acute reversible encephalitis. We describe a case of transient bilateral basal ganglia lesions after a prodromal gastroenteritis which completely resolved four months later. Diffusion weighted images were determinant to depict the basal ganglia abnormalities and were helpful to evaluate the prognosis. A review of the literature indicates that many diseases may be accompanied by signal abnormalities within the basal ganglia and that differential diagnosis is possible only through the simultaneous evaluation of imaging, clinical and laboratory findings.

Viral parkinsonism

Parkinson's disease is a debilitating neurological disorder that affects 1-2% of the adult population over 55 years of age. For the vast majority of cases, the etiology of this disorder is unknown, although it is generally accepted that there is a genetic susceptibility to any number of environmental agents. One such agent may be viruses. It has been shown that numerous viruses can enter the nervous system, i.e. they are neurotropic, and induce a number of encephalopathies. One of the secondary consequences of these encephalopathies can be parkinsonism, that is both transient as well as permanent. One of the most highlighted and controversial cases of viral parkinsonism is that which followed the 1918 influenza outbreak and the subsequent induction of von Economo's encephalopathy. In this review, we discuss the neurological sequelae of infection by influenza virus as well as that of other viruses known to induce parkinsonism including Coxsackie, Japanese encephalitis B, St. Louis, West Nile and HIV viruses.

Neuropsychological and psychiatric profiles in acute encephalitis in adults

Acute encephalitis is an inflammation of brain tissue that can result from activity in the central nervous system (CNS) of a number of viruses. Although the neurological and psychiatric effects of encephalitis in the acute phase of the illness are well-known (Caroff, Mann, Gliatto, Sullivan, & Campbell, 2001), larger scale studies of the pattern of neuropsychological and psychiatric impairment following recovery from the acute inflammatory phase are less apparent. This paper reports the results of neuropsychological testing with a range of standardised cognitive measures in a case series of long-term post-acute participants. Psychiatric abnormality is examined using the SCL-90-R self-report scale of distress (Derogatis, 1983). We also examined the role of emerging insight in the aetiology of depression in this population. Two clusters of cognitive dysfunction were observed, one group of primarily herpes simplex cases showing a severe generalised deficit across a number of cognitive domains and a second cluster showing a variety of more isolated disorders of executive function. Abnormally high levels of distress were reported by participants, with depression, obsessive-compulsive symptoms, interpersonal sensitivity and phobic anxiety most significantly increased. Depression was found to be least severe in those with most accurate insight into their problems. Examining the correlations between cognitive and psychiatric test results demonstrates a relationship between depression and interpersonal anxiety and specific cognitive measures. Obsessive-compulsive behaviour and phobic anxiety, however, appear to exist independently of the assessed cognitive deficits.

Systemic diseases that cause movement disorders

The present review is aimed at providing practical assistance to the clinical neurologist in reaching a diagnosis, understanding the pathogenic mechanisms of movement disorders associated with systemic diseases, and determining appropriate therapy. Infectious disease by direct effect or as an acquired autoimmune neurological disease, stroke, hypoxia-ischemia, paraneoplastic syndromes, collagen disorders, endocrine, liver and kidney diseases that may cause hypokinetic or hyperkinetic abnormal movement are considered separately. The type and evolution of abnormal movement caused by systemic disease vary with age and underlying pathology. Therapy for abnormal movements should include a primary treatment for the systemic disease.

Wild-type and attenuated influenza virus infection of the neonatal rat brain

Although influenza virus infection of humans has been associated with a wide spectrum of clinical neurological syndromes, the pathogenesis of influenza virus associated central nervous system (CNS) disease in humans remains controversial. To better study influenza virus neuropathogenesis, an animal model of influenza-associated CNS disease using human virus isolates without adaptation to an animal host was developed. This neonatal rat model of influenza virus CNS infection was developed using low-passage human isolates and shows outcomes in specific brain regions, cell types infected, and neuropathological outcomes that parallel the available literature on cases of human CNS infection. The degree of virus replication and spread in the rat brain correlated with the strains' neurotoxicity potential for humans. In addition, using sensitive neurobehavioral test paradigms, changes in brain function were found to be associated with areas of virus replication in neurons. These data suggest that further evaluation of this pathogenesis model may provide important information regarding influenza virus neuropathogenesis, and that this model may have possible utility as a preclinical assay for evaluating the neurological safety of new live attenuated influenza virus vaccine strains.

Influenza-associated acute encephalopathy in Japanese children in 1994–2002

We addressed the incidence of influenza-associated acute encephalopathy, which is distinct from Reye syndrome, in children in Japan. Eighty-nine children with a mean age of 3.8 years were reported to have developed this disease during eight influenza seasons (December 1994-April 2002) in Hokkaido, Japan. None of them had received aspirin. Most of the patients rapidly became comatose with or without convulsions with a mean interval of 1.7 days from the onset of fever to the onset of central nervous system symptoms. Thirty-three (37.1%) patients died and 17 (19.1%) patients had neurological sequelae. A total of 53 (59.6%) cases were proved to have an influenza virus infection. Interleukin-6 and tumor necrosis factor-alpha were markedly elevated in serum and cerebrospinal fluid samples from two patients who died after a rapid, fulminant course. A post-mortem examination of one fatal case revealed vasogenic brain edema with generalized vasculopathy, suggesting that the generalized impairment of vascular endothelial cells caused by highly activated cytokines plays a central role in the pathophysiology of this disease. We conclude that influenza-associated acute encephalopathy may be an underestimated syndrome and is another reason to promote vaccination against influenza in infants and younger children.

Influenza virus and CNS manifestations

Neurological involvement during influenza infection has been described during epidemics and is often consistent with serious sequelae or death. An increasing incidence of influenza-associated encephalitis/encephalopathy has been reported in Japan, mainly in children. A variety of other clinical CNS manifestations, such as Reye's syndrome, acute necrotising encephalopathy (ANE), and myelitis as well as autoimmune conditions, such as Guillain-Barre's syndrome, may occur during the course of influenza infection. Virological diagnosis is essential and based on virus isolation, antigen detection, RNA detection by PCR, and serological analyses. Neuroimaging with CT and MRI of the brain are of prognostic value. The pathogenic mechanisms behind the influenza CNS complications are unknown. The treatment is symptomatic, with control of vital functions in the intensive care unit, antiepileptic medication and treatment against brain oedema.

Effect of mass immunization against influenza encephalopathy on mortality rates in children

BACKGROUND

Since the Japanese influenza vaccination program for school children was terminated in 1994, a steep rise has been noted in the number of young children reported with fulminant influenza and influenza associated with acute encephalopathy/encephalitis. The purpose of the present study was to interpret and clarify the effect of mass influenza vaccination on mortality of Japanese children, aged <19 years, with influenza and influenza-associated acute encephalopathy/encephalitis.

METHODS

The authors examined the distribution of mortality rates of children in Japan aged <19 years with influenza during 1950-2000, influenza associated with central nervous system (CNS) signs in the period 1950-1978, and the estimated cases of influenza associated with acute encephalopathy/encephalitis in the period 1987-2000.

RESULTS

Total influenza mortality among children aged <19 years has increased since 1990, with children aged <4 years after 1994 being the worst affected. The mean values of mortality rates of influenza associated with central nervous system signs during 1963-1978 and the estimated mortality of children aged <9 years during 1979-1994 were significantly lower than in some years before 1962, and after 1995 (P < 0.05). The annual mortality rates of influenza-associated acute encephalopathy/encephalitis during 1995-2000 were significantly higher than the expected mortality of influenza associated with central nervous system signs in children aged <14 years (P < 0.05).

CONCLUSION

The results of the present study suggest that mass immunization of school-aged children reduced the mortality rate from influenza-associated acute encephalopathy/encephalitis in children less than 9 years of age.

Successful protection by amantadine hydrochloride against lethal encephalitis caused by a highly neurovirulent recombinant influenza A virus in mice

A mouse model system for a lethal encephalitis due to influenza has been established by stereotaxic microinjection with the recombinant R404BP strain of influenza A virus into the olfactory bulb of C57BL/6 mice. The virus infection spread selectively to neurons in nuclei of the broad areas of the brain parenchyma that have anatomical connections to the olfactory bulb, leading to apoptotic neurodegeneration. The inflammatory reaction at the extended stage of viral infection involved the vascular structures affected by induction of inducible nitric oxide synthase and protein nitration; those were related to the etiology of fatal brain edema. The intraperitoneal administration of amantadine inhibited the viral growth in the brain and saved mice from the lethal encephalitis. The severity of neuronal loss paralleled the time lag between the virus challenge and the start of amantadine treatment. Thus, early pharmacological intervention is essential to minimize neurological deficits due to influenza virus-induced neurodegeneration.

Influenza-associated encephalopathy in Japan

Although the clinical entity of influenza-associated encephalopathy (influenza encephalopathy) has not gained universal recognition, it has been reported frequently as a complication of influenza in Japanese children. The influenza type A (H3N2) virus was detected in most cases. Most of the patients have been young children. Influenza encephalopathy typically is associated with a sudden onset of high fever, severe convulsions, rapidly progressive coma, and death within 2 or 3 days. Influenza encephalopathy reported in Japan is distinct from Reye syndrome, and one-fourth of patients exhibit bilateral thalamic necrosis on neuroimaging. Similar encephalopathic symptoms probably occur in North America and European countries.

Influenza encephalopathy associated with infection with human herpesvirus 6 and/or human herpesvirus 7

Influenza-associated encephalopathy is often reported in young Japanese children, but its pathogenesis is unknown. Although influenza virus can be demonstrated by throat culture for patients with encephalopathy, cultures of samples of cerebrospinal fluids (CSF) do not yield the virus. Eight patients with encephalopathy or complicated febrile convulsions had influenza virus infection diagnosed by means of culture, polymerase chain reaction (PCR), or rapid diagnosis using throat swabs. In all 8 cases, the results of PCR testing of CSF specimens for influenza virus were negative. On the other hand, human herpesvirus 6 (HHV-6) DNA was demonstrated in CSF specimens obtained from 2 of 8 patients. In 3 of 8 patients, the presence of human herpesvirus 7 (HHV-7) DNA was demonstrated in CSF specimens. Some cases of influenza-associated encephalopathy reported in Japan may be attributable to a dual infection with influenza virus and HHV-6, -7, or both. Another possibility is that latent HHV-6 or HHV-7 in the brain is reactivated by influenza, causing encephalopathy or febrile convulsions.