Childhood encephalopathy: viruses, immune response, and outcome

Mental health outcomes of encephalitis: An international web-based study

BACKGROUND AND PURPOSE

Acute encephalitis is associated with psychiatric symptoms. Despite this, the extent of mental health problems following encephalitis has not been systematically reported.

METHODS

We recruited adults who had been diagnosed with encephalitis of any aetiology to complete a web-based questionnaire.

RESULTS

In total, 445 respondents from 31 countries (55.1% UK, 23.1% USA) responded. Infectious encephalitis constituted 65.4% of cases, autoimmune 29.7%. Mean age was 50.1 years, 65.8% were female, and median time since encephalitis diagnosis was 7 years. The most common self-reported psychiatric symptoms were anxiety (75.2%), sleep problems (64.4%), mood problems (62.2%), and unexpected crying (35.2%). Self-reported psychiatric diagnoses were common: anxiety (44.0%), depression (38.6%), panic disorder (15.7%), and posttraumatic stress disorder (PTSD; 21.3%). Severe mental illnesses such as psychosis (3.3%) and bipolar affective disorder (3.1%) were reported. Self-reported diagnosis rates were broadly consistent with results from the Psychiatric Diagnostic Screening Questionnaire. Many respondents also reported they had symptoms of anxiety (37.5%), depression (28.1%), PTSD (26.8%), or panic disorder (20.9%) that had not been diagnosed. Rates of psychiatric symptoms did not differ between autoimmune and infectious encephalitis. In total, 37.5% respondents had thought about suicide, and 4.4% had attempted suicide, since their encephalitis diagnosis. More than half of respondents (53.5%) reported they had no, or substandard, access to appropriate mental health care. High rates of sensory hypersensitivities (>75%) suggest a previously unreported association.

CONCLUSIONS

This large international survey indicates that psychiatric symptoms following encephalitis are common and that mental health care provision may be inadequate. We highlight a need for proactive psychiatric input.

Neuroimaging and neurological outcome of children with acute encephalitis

AIM

To investigate the severity of acute phase magnetic resonance imaging (MRI) findings and severity of acute illness as risk factors for disability after recovery from encephalitis.

METHOD

Children with encephalitis (n = 98; median age 6 years 10 months, interquartile range 3 years-11 years 6 months; 59 males, 39 females) treated in Turku University Hospital during the years 1995 to 2016 were identified in this retrospective cohort study. The acute phase (<2 months of symptom onset) brain MRIs were re-evaluated and classified based on the severity of neuroimaging finding by a neuroradiologist. Neurological outcome at discharge, at short-term (<3 months from discharge) follow-up, and at long-term (>1 year from discharge) follow-up was assessed from medical records using the Glasgow Outcome Scale.

RESULTS

Long-term recovery was poor in 24 of 82 (29%) children with follow-up data. Two children died, eight had severe disability, and 14 had moderate disability. Acute phase MRI was available for re-evaluation from 74 of 82 patients with follow-up data. The increasing severity of MRI findings was associated with need for ventilator therapy and with poor recovery.

INTERPRETATION

The risk for poor recovery in paediatric encephalitis is high, and it is associated with the severity of MRI findings.

WHAT THIS PAPER ADDS

Poor long-term recovery was found in 29% of children with encephalitis. Severe disability measured by Glasgow Outcome Scale was found in 8%. The most severe neuroimaging findings were a risk factor for severe acute illness and poor long-term recovery.

Reduced cerebrospinal fluid levels of interleukin-10 in children with febrile seizures

PURPOSE

The exact etiology of febrile seizures (FS) is still unclear. However, it is thought that cytokine network activation may have a causative role. Therefore, this study aimed to evaluate the levels of interleukin-12 (IL-12) as a proinflammatory cytokine, interleukin-10 (IL-10) as an anti-inflammatory cytokine, and interferon-β (IFN-β), a marker of toll-like receptor-3 activation as a host response to viruses. These cytokine levels were analyzed in the cerebrospinal fluid (CSF) of children after a FS.

METHODS

With the approval of the Human Research Ethics Committee, 76 patients with FS, who underwent lumbar puncture (LP) for the exclusion of central nervous system (CNS) infection, and who didn't have CSF pleocytosis, were included in the study. The control group consisted of 10 patients with similar ages, with an acute febrile illness and who required LP to exclude CNS infection. The analyses were made by the enzyme-linked immunoassay method.

RESULTS

Age, gender distribution and CSF IL-12 and IFN- β levels did not differ, but CSF IL-10 levels were significantly lower in the FS group as compared to the control group (0.78 ± 4.5 pg/ml, versus 27 ± 29 pg/ml, p < 0.0001).

CONCLUSION

The low-level of CSF IL-10, considering its anti-inflammatory properties, may play a role in the etiopathogenesis of FS.

Prognostic factors in the early phase of acute encephalopathy

BACKGROUND

Neurological sequelae occur in 40% of patients with acute encephalopathy (AE). The early prediction of poor outcomes is critical to the initiation of appropriate treatment. The aim of the present study was therefore to elucidate prognostic factors that can be quickly and feasibly evaluated on hospital admission in patients with AE.

METHODS

We analyzed data from 51 AE patients admitted to Hirakata City Hospital between January 2005 and December 2014. Age at onset, sex, underlying disease, status epilepticus (SE), presence of benzodiazepine-resistant SE (BZD-resistant SE), and basic blood serum parameters on admission were evaluated in relation to each patient's outcome.

RESULTS

On univariate analysis age at onset, BZD-resistant SE, and serum aspartate aminotransferase (AST), alanine aminotransferase, lactate dehydrogenase, and platelet count varied significantly according to outcome. On multivariate analysis age at onset (≤21 months), presence of BZD-resistant SE, and AST (≥46 IU/L) were identified as independent variables associated with poor outcome.

CONCLUSION

Age at onset, presence of BZD-resistant SE, and AST are associated with a poor prognosis in AE.

Long-Term Outcomes and Risk Factors Associated With Acute Encephalitis in Children

BACKGROUND

Factors associated with poor outcomes of children with encephalitis are not well known. We sought to determine whether electroencephalography (EEG) findings, magnetic resonance imaging (MRI) abnormalities, or the presence of seizures at presentation were associated with poor outcomes.

METHODS

A retrospective review of patients aged 0 to 21 years who met criteria for a diagnosis of encephalitis admitted between 2000 and 2010 was conducted. Parents of eligible children were contacted and completed 2 questionnaires that assessed current physical and emotional quality of life and neurological deficits at least 1 year after discharge.

RESULTS

During the study period, we identified 142 patients with an International Classification of Diseases 9th Revision diagnosis of meningitis, meningoencephalitis, or encephalitis. Of these patients, 114 met criteria for a diagnosis of encephalitis, and 76 of these patients (representing 77 hospitalizations) had complete data available. Forty-nine (64%) patients were available for follow-up. Patients admitted to the intensive care unit were more likely to have abnormal EEG results (P = .001). The presence of seizures on admission was associated with ongoing seizure disorder at follow-up. One or more years after hospitalization, 78% of the patients had persistent symptoms, including 35% with seizures. Four (5%) of the patients died. Abnormal MRI findings and the number of abnormal findings on initial presentation were associated with lower quality-of-life scores.

CONCLUSIONS

Encephalitis leads to significant morbidity and death, and incomplete recovery is achieved in the majority of hospitalized patients. Abnormal EEG results were found more frequently in critically ill children, patients with abnormal MRI results had lower quality-of-life scores on follow-up, and the presence of seizures on admission was associated with ongoing seizure disorder and lower physical quality-of-life scores.

Ophthalmological findings in children with encephalitis

PURPOSE

To evaluate ophthalmological abnormalities in children with acute encephalitis.

METHODS

Thirty-six children included in a hospital-based prospectively and consecutively collected cohort of children with acute encephalitis were investigated for ophthalmological abnormalities. The investigation included clinical ophthalmological examination, fundus photography, neuro-ophthalmological examinations as well as visual and stereo acuity. Results on laboratory examinations, clinical findings, neuroimaging and electroencephalography registrations were recorded for all children.

RESULTS

The median age was 4.0 years (Interquartile Range 1.9-9.8). The aetiology was identified in 74% of cases. Three of 36 patients were found to have abnormal ophthalmological findings related to the encephalitis. Transient sixth nerve palsy was seen in a 15-year-old child and transient visual impairment was seen in a 3.5-year-old child. Bilateral miosis and ptosis, i.e. autonomic nerve system symptoms, were seen in an 11-month-old child, with herpes simplex 1 and N-methyl-d-aspartate receptor antibody encephalitis. All three children recovered and improved their ophthalmological function with time.

CONCLUSION

Only 3 of 36 children were found to have ophthalmological abnormalities due to encephalitis and they all improved with time. Thus, ophthalmological consultation does not seem to fit in a screening programme for childhood encephalitis but should be considered in selected cases.

Long-term outcomes of infective encephalitis in children: a systematic review and meta-analysis

AIM

The long-term outcomes of childhood infective encephalitis are variable and not well quantified. We aimed to systematically review the literature and undertake meta-analyses on predetermined outcomes to address this knowledge gap and identify areas for future research.

METHOD

We searched electronic databases, performed complementary reviews of references of fully extracted articles, and made contact with experts on infective encephalitis. Articles published up until April 2016 were selected for screening.

RESULTS

We evaluated sequelae of 1018 survivors of childhood infective encephalitis (934 with complete follow-up) from 16 studies. Mean age during acute encephalitis episodes was 5 years 3.6 months (range 1.2mo-17y), 57.6% were male (500/868), and mean follow-up period was 4 years 1.2 months (range 1-12y). Incomplete recovery was reported in 312 children (42.0%; 95% confidence interval [CI] 31.6-53.1% in pooled estimate). Among the other sequelae, developmental delay, abnormal behaviour, motor impairment, and seizures were reported among 35.0% (95% CI 10.0-65.0%), 18.0% (95% CI 8.0-31.0%), 17.0% (95% CI 10.0-26.0%), and 10.0% (95% CI 6.0-14.0%) respectively.

INTERPRETATION

Almost half of childhood infective encephalitis survivors report incomplete recovery in the long-term; most commonly developmental delay, behavioural abnormality, and neurological impairments (i.e. seizure). Well designed, large-scale prospective studies are needed to better quantify neurodevelopmental sequelae among childhood encephalitis survivors.

Acute Childhood Encephalitis at 2 Tertiary Care Children's Hospitals in Israel: Etiology and Clinical Characteristics

OBJECTIVES

The clinical characteristics, pathogens, and outcome were analyzed to investigate the etiology of acute pediatric encephalitis in 2 tertiary pediatric medical centers in Israel.

METHODS

A retrospective study among children aged 1 month to 18 years hospitalized with the diagnosis of acute encephalitis between January 1999 and December 2009. Data on presenting symptoms, clinical findings, microbiological, virologic, electroencephalographic and neuroimaging studies, laboratory results, and hospital course were retrieved from the medical records and the computerized microbiology database.

RESULTS

Forty-four children were included. An etiologic agent was identified in 11 (25%): Mycoplasma pneumoniae (n = 2), enterovirus (n = 3), herpes simplex virus (HSV) (n = 1), Epstein-Barr virus (n = 2), human herpes virus 6 (n = 1), influenza virus type A (n = 1), and varicella zoster virus (n = 1). Presenting features included fever (90% of patients), seizures (39%), focal neurological signs (18%), and decreased consciousness (67%). Diagnostic findings included pleocytosis in the cerebrospinal fluid (76% of patients), electroencephalographic abnormalities (78%), and neuroimaging abnormalities (34%). All patients were treated with acyclovir until negative result for HSV polymerase chain reaction was received from cerebrospinal fluid, the child with HSV encephalitis was treated with intravenous acyclovir for 3 weeks. The outcomes at the time of discharge were: normal (66%), motor difficulties (14%), global neurological deficits (7%), visual defects (2%), and hearing impairment (2%) and no deaths.

CONCLUSIONS

The etiology of acute encephalitis remains unknown in the majority of cases. There was no correlation between adverse outcome and a specific etiologic agent. The high morbidity rate may suggest that current therapeutic modalities may not be sufficient.

Neurological Outcomes After Presumed Childhood Encephalitis

OBJECTIVE

To evaluate factors during acute presumed childhood encephalitis that are associated with development of long-term neurological sequelae.

METHODS

A total of 217 patients from Rady Children's Hospital San Diego with suspected encephalitis who met criteria for the California Encephalitis Project were identified. A cohort of 99 patients (40 females, 59 males, age 2 months-17 years) without preexisting neurological conditions, including prior seizures or abnormal brain magnetic resonance imaging scans was studied. Mean duration of follow-up was 29 months. Factors that had a relationship with the development of neurological sequelae (defined as developmental delay, learning difficulties, behavioral problems, or focal neurological findings) after acute encephalitis were identified.

RESULTS

Neurological sequelae at follow-up was associated with younger age (6.56 versus 9.22 years) at presentation (P = 0.04) as well as an initial presenting sign of seizure (P = 0.03). Duration of hospital stay (median of 7 versus 15.5 days; P = 0.02) was associated with neurological sequelae. Of the patients with neurological sequelae, a longer hospital stay was associated with patients of an older age (P = 0.04). Abnormalities on neuroimaging (P = 1.00) or spinal fluid analysis (P = 1.00) were not uniquely associated with neurological sequelae. Children who were readmitted after their acute illness (P = 0.04) were more likely to develop neurological sequelae. There was a strong relationship between the patients who later developed epilepsy and those who developed neurological sequelae (P = 0.02).

SIGNIFICANCE

Limited data are available on the long-term neurological outcomes of childhood encephalitis. Almost half of our patients were found to have neurological sequelae at follow-up, indicating the importance of earlier therapies to improve neurological outcome.

Long-term motor and cognitive outcome of acute encephalitis

OBJECTIVES

To examine the long-term motor and neurocognitive outcome of children with acute encephalitis and to look at possible prognostic factors.

METHODS

Children who were treated for acute encephalitis in 2000-2010 were reevaluated. All children and their parents were interviewed by using structured questionnaires, and the children underwent full neurologic examinations, along with comprehensive neurocognitive, attention, and behavioral assessments.

RESULTS

Of the 47 children enrolled, 1 died and 29 had neurologic sequelae, including motor impairment, mental retardation, epilepsy, and attention and learning disorders. Children with encephalitis had a significantly higher prevalence of attention-deficit/hyperactivity disorder (50%) and learning disabilities (20%) compared with the reported rate (5%-10%) in the general population of Israel (P < .05) and lower IQ scores. Lower intelligence scores and significantly impaired attention and learning were found even in children who were considered fully recovered at the time of discharge. Risk factors for long-term severe neurologic sequelae were focal signs in the neurologic examination and abnormal neuroimaging on admission, confirmed infectious cause, and long hospital stay.

CONCLUSIONS

Encephalitis in children may be associated with significant long-term neurologic sequelae. Significant cognitive impairment, attention-deficit/hyperactivity disorder, and learning disabilities are common, and even children who were considered fully recovered at discharge may be significantly affected. Neuropsychological testing should be recommended for survivors of childhood encephalitis.

Childhood rubella encephalitis: diagnosis, management, and outcome

We to report clinical biological and radiologic features of rubella encephalitis in childhood and assess its prognostic impact. Our retrospective study was conducted in an intensive care unit of a university hospital in Sfax, Tunisia. Twenty-one children (age range, 1-15 years) were included. Median age was 9 years (lower and upper quartiles, 7-11 years). On admission, generalized maculopapular eruption was found in 17 cases (81%). Median Glasgow Coma Scale score was 7 (lower and upper quartiles, 7-8). Twenty patients (95.2%) experienced at least 1 episode of seizures. Sixteen patients (76.2%) developed a status epilepticus. The result for enzyme-linked immunosorbent assay detecting anti-rubella immunoglobulin (M) was positive in the serum and in the cerebrospinal fluid samples for all our patients. Magnetic resonance imaging (MRI) of the brain was performed on admission for 3 patients (14.3%) and within a median of 4 days (lower and upper quartiles, 2-6 days) for 8 patients. The test was normal in 6 cases. Two deaths were recorded (9.5%). Survivors had no neurological sequelae 6 months after intensive care unit discharge.

Epidemiology of infectious encephalitis, differences between a prospective study and hospital discharge data

The French epidemiology of infectious encephalitis has been described in a 2007 prospective study. We compared these results with available data (demographic features, causative agents, case-fatality ratio) obtained through the French national hospital discharge 2007 database (PMSI), in order to evaluate it as a surveillance tool for encephalitis. Causative agents were identified in 52% of cases in the study, and 38% in PMSI (P < 0·001). The incidence of encephalitis in France in 2007 was estimated as 2·6 cases/100 000 inhabitants. HSV and VZV were the most frequent aetiological agents in both databases with similar rates. Listeria monocytogenes and Mycobacterium tuberculosis were less frequent in PMSI than in the study (Listeria: 2% vs. 5%, P = 0·001; Mycobacterium: 2% vs. 8%, P < 0·001). The case-fatality ratios were similar, except for Listeria (46% in the study vs. 16%). Nevertheless, despite the absence of case definitions and a possible misclassification weakening PMSI data, we suggest that PMSI may be used as a basic surveillance tool at a limited cost.

Causes of encephalitis and differences in their clinical presentations in England: a multicentre, population-based prospective study

BACKGROUND

Encephalitis has many causes, but for most patients the cause is unknown. We aimed to establish the cause and identify the clinical differences between causes in patients with encephalitis in England.

METHODS

Patients of all ages and with symptoms suggestive of encephalitis were actively recruited for 2 years (staged start between October, 2005, and November, 2006) from 24 hospitals by clinical staff. Systematic laboratory testing included PCR and antibody assays for all commonly recognised causes of infectious encephalitis, investigation for less commonly recognised causes in immunocompromised patients, and testing for travel-related causes if indicated. We also tested for non-infectious causes for acute encephalitis including autoimmunity. A multidisciplinary expert team reviewed clinical presentation and hospital tests and directed further investigations. Patients were followed up for 6 months after discharge from hospital.

FINDINGS

We identified 203 patients with encephalitis. Median age was 30 years (range 0-87). 86 patients (42%, 95% CI 35-49) had infectious causes, including 38 (19%, 14-25) herpes simplex virus, ten (5%, 2-9) varicella zoster virus, and ten (5%, 2-9) Mycobacterium tuberculosis; 75 (37%, 30-44) had unknown causes. 42 patients (21%, 15-27) had acute immune-mediated encephalitis. 24 patients (12%, 8-17) died, with higher case fatality for infections from M tuberculosis (three patients; 30%, 7-65) and varicella zoster virus (two patients; 20%, 2-56). The 16 patients with antibody-associated encephalitis had the worst outcome of all groups-nine (56%, 30-80) either died or had severe disabilities. Patients who died were more likely to be immunocompromised than were those who survived (OR = 3·44).

INTERPRETATION

Early diagnosis of encephalitis is crucial to ensure that the right treatment is given on time. Extensive testing substantially reduced the proportion with unknown cause, but the proportion of cases with unknown cause was higher than that for any specific identified cause.

FUNDING

The Policy Research Programme, Department of Health, UK.

Biomarkers of inflammatory and auto-immune central nervous system disorders

PURPOSE OF REVIEW

Inflammatory and auto-immune disorders of the central nervous system are a heterogeneous group of disorders. Many of these disorders are potentially treatable with immune therapies that can reduce disability or prevent death. We review the clinical value of biomarkers which can aid in the diagnosis of paediatric inflammatory and auto-immune central nervous system (CNS) disorders.

RECENT FINDINGS

This review will first describe the clinical usefulness of nonspecific biomarkers of CNS inflammation such as cerebrospinal fluid neopterin and oligoclonal bands. Neopterin is produced by immune and neuronal cells after stimulation by interferon species and is increased in a broad range of inflammatory and auto-immune CNS disorders. Oligoclonal bands represent clonal production of immunoglobulin G in the CNS and are present in demyelinating, auto-immune, and infectious CNS disorders. In addition, we will review new advances in the immunogenetic investigation of familial auto-inflammatory disorders such as Aicardi-Goutières syndrome and Chronic Infantile Neurologic Cutaneous Articular syndrome. Finally, we will review the clinical utility of auto-antibodies in CNS disorders, with specific focus on auto-antibodies that bind to cell surface proteins such as N-methyl-D-asparate receptor, voltage-gated potassium channels, myelin oligodendrocyte glycoprotein, and aquaporin-4.

SUMMARY

These biomarkers are increasingly important in the recognition and treatment of inflammatory and auto-immune CNS disorders. Like many biomarkers in paediatric practice, it is essential to interpret the findings in the context of the patient history and examination.

Long-term outcomes of acute encephalitis in childhood

OBJECTIVES

The aims of this study were to investigate the long-term outcomes of childhood encephalitis and to examine possible prognostic factors.

METHODS

Of 93 children who were treated for acute encephalitis in 2000-2004, 71 were eligible for follow-up evaluations. A structured interview, using 2 questionnaires, was conducted with the parents. Fifteen of the children with the most-severe symptoms at the time of discharge also underwent electroencephalographic recording and tests of reaction times and working memory.

RESULTS

Persisting symptoms were reported by 54% of children. The predominant symptoms were personality changes and cognitive problems. Children who made a complete recovery did so within 6 to 12 months. The only significant risk factor for sequelae was disease severity leading to admission to the ICU. The risk of subsequent epilepsy was increased for children with seizures at presentation. Most follow-up electroencephalograms showed improvement, but results had not normalized for 9 of 15 children. Children with encephalitis had slower reaction times, compared with control subjects, but no difference in working memory could be seen.

CONCLUSION

Persisting symptoms after childhood encephalitis were present for a substantial number of children. Seizures increased the risk of subsequent epilepsy; the only other prognostic marker was admission to the ICU. Even children who were considered fully recovered at discharge reported persisting symptoms at follow-up evaluations. Children who made a full recovery did so within 6 to 12 months, which suggests that all children with encephalitis should be monitored for 1 year after the acute illness.

Childhood encephalitis in Sweden: etiology, clinical presentation and outcome

Acute encephalitis is a relatively uncommon but potentially harmful CNS inflammation usually caused by infection. The diagnosis is difficult to establish and the etiology often remains unclear. Furthermore, the long-term prognosis of acute encephalitis in children is poorly described. In this study, we characterize childhood encephalitis from a Swedish perspective in regard to etiology, clinical presentation and sequele. We retrospectively studied all children (n=93) who were admitted for acute encephalitis at Karolinska University Hospital in Stockholm during 2000-2004. A confirmed etiological agent was identified in eight cases and a probable one in 37; in 48 cases no etiological agent could be found. Tick-borne encephalitis virus, enterovirus, respiratory syncytial virus, varicella zoster virus and influenza virus predominated and represented 67% of all the confirmed or probable etiologies. Encephalopathy was present in 80% of the children, 81% had fever, 44% had focal neurological findings, and seizures occurred in 40%. EEG abnormalities were seen in 90% and abnormal neuroimaging was present in 30%. The cerebrospinal fluid showed pleocytosis in 55%. There was no mortality, but 60% of the children had persisting symptoms at the time of discharge, 41% of which were moderate to severe. We conclude that the etiology of encephalitis among Swedish children is at large the same as in other European countries with similar vaccination programs. Fever and encephalopathy were seen in a majority of children and the most sensitive tool for making the diagnosis was EEG examination. Furthermore, many children display persisting sequele at discharge for which the strongest predictive factor was focal neurological findings at presentation.

Intrathecal synthesis of anti-viral antibodies in pediatric patients

INTRODUCTION

Detection of intrathecal synthesis of specific antibodies (antibody index (AI)) is an established method to prove cerebral viral infection. Experience on its clinical application in large patient groups, however, is sparse.

METHODS

Retrospective analysis of pediatric patients with positive viral AI treated at RWTH Aachen University Hospital between 1999 and 2005.

RESULTS

63 patients were studied, including 14 with encephalitis, 12 with neuritis, nine with cerebral vasculitis, six with multiple sclerosis (MS), five with severe cephalgia, five with psychiatric symptoms, three with hearing loss, two with seizures, three with white matter diseases, two with movement disorders, one with meningococcal meningitis and one with sinus venous thrombosis. Seven had several positive AI among them only one patient with MS. Of the 51 patients with a single positive AI and not having MS, 16 showed a positive AI for herpes simplex-, 13 for varicella zoster-, nine for Epstein-Barr-, four for cytomegalo-, four for mumps-, three for rubella- and two for measles virus. Frequent combinations were varicella zoster virus (VZV) and vasculitis (n = 8), herpes simplex virus (HSV) and neuritis (n = 6), Epstein-Barr virus (EBV) (n = 5), respectively, VZV (n = 4) and encephalitis as wells as mumps virus (n = 2) and hearing loss. Matched polymerase chain reaction (PCR) and AI data were available in 25 patients. PCR was simultaneously positive in three cases only.

DISCUSSION

AI testing identifies a similar spectrum of pathogens as known from cerebrospinal fluid (CSF) PCR studies. It complements the PCR and increases the chance for adequate diagnosis and treatment of patients with assumed cerebral viral infections.

Role of viral infections in the etiology of febrile seizures

The role of viral infection in the etiology of febrile seizures is a relatively neglected field of neurologic research. A National Institutes of Health Consensus Conference (1981) omitted reference to causes of infections and the role of fever in febrile seizures, and emphasized outcome and anticonvulsant treatment. In an earlier review of the world literature (1924-1964), except for roseola infantum, viral infections as a cause of febrile seizures were rarely diagnosed. The present review includes reports of viruses most commonly associated with febrile seizures in the last decade, especially human herpesvirus-6 and influenza. The specificity and neurotropic properties of some viruses in the febrile seizure mechanism, a possible encephalitic or encephalopathic pathology, and the essential role of fever and height of the body temperature as a measure of the febrile seizure threshold are discussed. Cytokine and immune response to infection, and a genetic susceptibility to febrile seizures are additional etiologic factors. Future research should emphasize early detection of causative viruses, the nature of viral neurotropism, and the role of cytokines in fever induction. Trials of antiviral agents and vaccines, with attention to safety concerns, and more effective antipyretics would address the febrile seizure mechanism more specifically than anticonvulsant therapies.