Human herpesviruses and neurological disorders of childhood

Detection of HHV-6 and EBV and Cytokine Levels in Saliva From Children With Seizures: Results of a Multi-Center Cross-Sectional Study

Background and Objective: One third of children with epilepsy are refractory to medications. Growing data support a role of common childhood infections with neurotropic viruses and inflammation in epileptogenesis. Our objective was to determine the frequency of Human Herpesvirus-6 (HHV-6) and Epstein-Barr Virus (EBV) infection and cytokine levels in saliva from children with seizures compared to healthy controls and to controls with a febrile illness without seizures. Methods: In this cross-sectional multi-center study, we collected saliva from 115 consecutive children with acute seizures (cases), 51 children with a fever and no seizures or underlying neurological disease (fever controls) and 46 healthy children (healthy controls). Specimens were analyzed by a novel droplet digital PCR for HHV-6 and EBV viral DNA and a bead-based immunoassay for neuroinflammatory cytokines. Results: Cases included febrile seizures (n = 30), acute seizures without (n = 53) and with fever (n = 4) in chronic epilepsy, new onset epilepsy (n = 13), febrile status epilepticus (n = 3), and first lifetime seizure (n = 12). HHV-6 DNA was found in 40% of cases vs. 37% fever controls and 35% healthy controls, with no statistically significant differences. EBV DNA was also detected with no differences in 17% cases, 16% fever controls, and 28% healthy controls. IL-8 and IL-1β were increased in saliva of 32 random samples from cases compared with 30 fever controls: IL-8 cases mean (SD): 1158.07 pg/mL (1427.41); controls 604.92 (754.04); p = 0.02. IL-1β 185.76 (230.57); controls 86.99 (187.39); p = 0.0002. IL-1β level correlated with HHV6 viral load (p = 0.007). Conclusion: Increase in inflammatory cytokines may play a role in the onset of acute seizures and saliva could represent an inexpensive and non-invasive method for detection of viral DNA and cytokines.

Viral and Prion Infections of the Central Nervous System: Radiologic-Pathologic Correlation: From the Radiologic Pathology Archives

Viral infections of the central nervous system (CNS) range in clinical severity, with the most severe proving fatal within a matter of days. Some of the more than 100 different viruses known to affect the brain and spinal cord are neurotropic with a predilection for producing CNS infection. The host response to viral infection of the CNS is responsible for the pathophysiology and imaging findings seen in affected patients. Viral CNS infections can take the form of meningitis, encephalitis, encephalomyelitis, or, when involving the spinal cord and nerve roots, encephalomyeloradiculitis. In 1982, an infectious particle termed a prion that lacked nucleic acid and therefore was not a virus was reported to produce the fatal neurodegenerative disease Creutzfeldt-Jakob disease and related disorders. These prion diseases produce characteristic neuroimaging findings that are distinct from those seen in most viral infections. The clinical and imaging findings associated with viral CNS infection are often nonspecific, with microbiologic analysis of cerebrospinal fluid the most useful single test allowing for diagnosis of a specific viral infection. This review details the spectrum of viral CNS infections and uses case material from the archives of the American Institute for Radiologic Pathology, with a focus on the specific clinical characteristics and magnetic resonance imaging features seen in these infections. Where possible, the imaging features that allow distinction of these infections from other CNS inflammatory conditions are highlighted.

Multiplex real-time PCR for the simultaneous detection of herpes simplex virus, human herpesvirus 6, and human herpesvirus 7

A simultaneous detection system to quantify HSV, HHV-6, and HHV-7 DNA via multiplex real-time PCR using different fluorochromes was developed. The minimum quantitative level established via this multiplex assay was four copies per reaction for HSV type 1, four copies for HHV-6, and three copies for HHV-7, respectively. The dynamic range encompassed at least six orders of magnitude. The system was specific and reproducible even in the presence of large amounts of other viral DNA. We then applied this multiplex real-time PCR assay to 105 CSF specimens obtained from subjects less than 15 years old in whom a diagnosis of viral encephalitis/encephalopathy was suspected on clinical grounds. The detection rate for each viral DNA was 6.7% for HSV, 9.5% for HHV-6, and 1.9% for HHV-7. These results indicate that our system is reliable and may be useful for the rapid diagnosis of viral encephalitis/encephalopathy.

Epstein-Barr virus-associated meningoencephalomyelitis: intrathecal reactivation of the virus in an immunocompetent child

Neurologic complications, including meningoencephalitis, transverse myelitis, and peripheral neuropathy, have been reported in patients with acute infectious mononucleosis. Chronic active Epstein-Barr virus and human immunodeficiency virus infections occasionally induce central nervous system lymphoma. On the other hand, central nervous system disease alone associated with Epstein-Barr virus rarely occurs in previously healthy individuals. A 15-year-old girl who developed acute disseminated encephalomyelitis-like disease presenting fever, anuresis, diplopia, and muscle weakness is described here. Clinical and neuroimaging studies led to the diagnosis of encephalomyelitis. Despite the absence of infectious mononucleosis-like symptoms, anti-Epstein-Barr virus antibody titers in serum and cerebrospinal fluid showed the virus reactivation. The copy number of Epstein-Barr virus DNA increased in cerebrospinal fluid but not in peripheral blood. Ganciclovir and repeated methyl-prednisolone pulse therapy resulted in complete resolution. Central nervous system disease on the limited intrathecal reactivation of Epstein-Barr virus in immunocompetent children should be differentiated from acute disseminated encephalomyelitis.

Central nervous system infections of herpesvirus family

Herpesviruses are one of the most common groups of pathogens causing central nervous system infections in humans. They mostly cause encephalitis, meningitis, or myelitis in immunocompetent and immunocompromised patients. Children, adults, and the elderly can all be affected. Although contrast-enhanced CT is more widely used for diagnosis, contrast-enhanced MR imaging combined with diffusion-weighted imaging is superior to CT in the detection of early changes and the real extent of the disease, and in assessing prognosis and monitoring response to antiviral treatment. More sophisticated techniques, such as MR spectroscopy and perfusion imaging, can aid in the differential diagnosis of herpesvirus infections from other tumoral, demyelinating, and ischemic processes.

Pediatric Epstein-Barr virus-associated encephalitis: 10-year review

Many neurologic manifestations of Epstein-Barr virus (EBV) infection have been documented, including encephalitis, aseptic meningitis, transverse myelitis, and Guillain-Barré syndrome. These manifestations can occur alone or coincidentally with the clinical picture of infectious mononucleosis. Since 1994, The Hospital for Sick Children has maintained a prospective registry of all children admitted with acute encephalitis. This report summarizes all cases of Epstein-Barr virus-associated encephalitis compiled from 1994 to 2003. Twenty-one (6%) of 216 children, median age 13 years (range 3-17 years), in the Encephalitis Registry were identified as having evidence of Epstein-Barr virus infection. This evidence consisted of convincing Epstein-Barr virus serology and/or positive cerebrospinal fluid polymerase chain reaction (PCR). One patient had symptoms of classic infectious mononucleosis; all others had a nonspecific prodrome, including fever (n = 17; 81%) and headache (n = 14; 66%). Slightly less than half (n = 10; 48%) had seizures and often had electroencephalograms showing a slow background (n = 12; 57%). Many demonstrated cerebrospinal fluid pleocytosis (n = 17; 81%), and 71% (n = 15) had abnormal magnetic resonance imaging findings. Two patients died, 2 suffered mild deficits, and 16 were neurologically normal at follow-up. Most patients with Epstein-Barr virus encephalitis do not show typical symptoms of infectious mononucleosis. Establishing a diagnosis of Epstein-Barr virus encephalitis can be difficult, and, consequently, a combination of serologic and molecular techniques should be used when investigating a child with acute encephalitis. Most children make full recoveries, but residual neurologic sequelae and even death can and do occur.

Neurological complications of acute and persistent Epstein-Barr virus infection in paediatric patients

Neurological complications of Epstein-Barr virus (EBV) have been reported almost exclusively in the course of acute primary infections. The role of EBV in paediatric neurological disease was investigated prospectively over a 2-year period, searching for acute primary, chronic, and reactivated EBV infections. Active EBV infections were diagnosed in 10/48 patients, including two with acute primary EBV infections (cranial neuritis and cerebellitis), one with chronic active infection (T/NK cell lymphoma with cranial neuritis), and seven with reactivated infections. Among these seven patients, three showed "Alice in Wonderland" syndrome, one facial nerve palsy, one progressive macrocephaly, and two prolonged encephalitic illness. The prognosis was good except for the patient with lethal T/NK cell lymphoma and the two girls with encephalitic illness. Despite steroid treatment, these girls suffered prolonged cognitive impairment and epileptic seizures. Both developed left-sided hippocampal atrophy, and one of them hippocampal sclerosis. Like primary infections, reactivated EBV infections cause neurological complications in a considerable number of paediatric patients, lead to serious long-term complications, and may contribute to the pathogenesis of hippocampal lesions.