Acute viral encephalitis: its diagnosis and outcome

Neuropsychological and psychiatric outcomes in encephalitis: A multi-centre case-control study

Objectives

Our aim was to compare neuropsychological and psychiatric outcomes across three encephalitis aetiological groups: Herpes simplex virus (HSV), other infections or autoimmune causes (Other), and encephalitis of unknown cause (Unknown).

Methods

Patients recruited from NHS hospitals underwent neuropsychological and psychiatric assessment in the short-term (4 months post-discharge), medium-term (9–12 months after the first assessment), and long-term (>1-year). Healthy control subjects were recruited from the general population and completed the same assessments.

Results

Patients with HSV were most severely impaired on anterograde and retrograde memory tasks. In the short-term, they also showed executive, IQ, and naming deficits, which resolved in the long-term. Patients with Other or Unknown causes of encephalitis showed moderate memory impairments, but no significant impairment on executive tests. Memory impairment was associated with hippocampal/medial temporal damage on magnetic resonance imaging (MRI), and naming impairment with left temporal and left frontal abnormalities. Patients reported more subjective cognitive complaints than healthy controls, with tiredness a significant problem, and there were high rates of depression and anxiety in the HSV and the Other encephalitis groups. These subjective, self-reported complaints, depression, and anxiety persisted even after objectively measured neuropsychological performance had improved.

Conclusions

Neuropsychological and psychiatric outcomes after encephalitis vary according to aetiology. Memory and naming are severely affected in HSV, and less so in other forms. Neuropsychological functioning improves over time, particularly in those with more severe short-term impairments, but subjective cognitive complaints, depression, and anxiety persist, and should be addressed in rehabilitation programmes.

Plasticity versus chronicity: Stable performance on category fluency 40 years post-onset

What is the long-term trajectory of semantic memory deficits in patients who have suffered structural brain damage? Memory is, per definition, a changing faculty. The traditional view is that after an initial recovery period, the mature human brain has little capacity to repair or reorganize. More recently, it has been suggested that the central nervous system may be more plastic with the ability to change in neural structure, connectivity, and function. The latter observations are, however, largely based on normal learning in healthy subjects. Here, we report a patient who suffered bilateral ventro-medial damage after presumed herpes encephalitis in 1971. He was seen regularly in the eighties, and we recently had the opportunity to re-assess his semantic memory deficits. On semantic category fluency, he showed a very clear category-specific deficit performing better that control data on non-living categories and significantly worse on living items. Recent testing showed that his impairments have remained unchanged for more than 40 years. We suggest cautiousness when extrapolating the concept of brain plasticity, as observed during normal learning, to plasticity in the context of structural brain damage.

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.

[Altered state of consciousness as a factor affecting the course and consequences of acute viral encephalitis]

INTRODUCTION

Acute viral encephalitis is an infectious disease, which is characterized by sudden onset, serious clinical picture and with an uncertain outcome. Disturbances of consciousness are common in the course of acute viral encephalitis. Consciousness is the heighest form of psychic life and consciousness disturbances may include quantitative (somnolentia, sopor, coma) and qualitative symptoms (convulsions, twilight state).

MATERIAL AND METHODS

We investigated 63 patients with acute viral encephalitis. The youngest patient was 15, and the oldest one 69 years of age. We examined the state of consciousness in all patients.

RESULTS

Of all examined patients, 54 (85.72%) patients had disturbances of consciousness, 9 (14.25%) patients had no conciousness disturbances, 11 (17.46%) patients had sopor and 24 (38.09%) patients were in coma. The highest percentage of lethal outcomes was recorded in coma patients (12.5%). The longer the duration of consciousness disturbances, the higher the mortality among these patients.

DISCUSSION

Subjective and objective factors cause different grades and duration of consciousness disturbances. The highest percentage of patients who recovered without consequences was established in the group of patients (81.82%) with somnolence. The highest percentage of patients who recovered with consequences (20.8%) and patients (12.5%) with lethal outcome was recorded in the group of patients in coma. These findings are in correlation with literature data.

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.

Neuropsychological sequelae of acute-onset sporadic viral encephalitis

Acute encephalitis is an inflammation of the brain parenchyma. In the USA, by estimation, 20,000 cases occur every year. A variety of cognitive deficits may persist after the acute stage, and they are often the sole cause of disability. Recent literature demonstrates the heterogeneity of both amnestic disorders and the outcome following encephalitis. Herpes simplex virus is the most commonly recognised single aetiology of sporadic encephalitis and it may be the cause of the most severe symptoms. Antiviral medication, however, seems to have improved the cognitive outcome when compared to the historical, untreated cases. The cognitive sequelae following herpes simplex virus encephalitis (HSVE) are best known and most commonly described, e.g., in textbooks, but they do not represent the typical symptomatology of encephalitis in general. Much less is unfortunately known about other types of encephalitis, those that account perhaps up to 80% of all cases, where both mild and severe defects have been observed. This article summarises the current knowledge.

A medical overview of encephalitis

Encephalitis is uncommon but is a neurological emergency which must be considered in a patient presenting with altered consciousness. Encephalitis is a diffuse inflammatory process of the brain parenchyma associated with evidence of brain dysfunction. The presentation of encephalitis can be acute or chronic. The aetiology of encephalitis can be broadly divided into two major subtypes. (1) Infection-related encephalitis which is a direct consequence of pathogenic viral, bacterial or parasitic agents. Herpes simplex virus (HSV) and varicella-zoster virus (VZV) are the most common cause of acute infectious encephalitis. (2) Autoimmune-mediated encephalitis which is mediated by an aberrant immune response. This can be triggered by a recent viral infection or vaccination. An example of this would be acute disseminated encephalitis (ADEM). This article will focus on the medical management of acute encephalitis. This will involve an extensive overview of the literature reviewing the diagnosis, investigation and treatment of acute viral encephalitis, ADEM and acute haemorrhagic leukoencephalopathy (AHLE). Encephalitis can also present chronically, and some of the different types of chronic encephalitis will be discussed.

Infection-associated encephalopathies: their investigation, diagnosis, and treatment

Reduced level of consciousness is a common clinical finding in acutely sick patients. In the majority of cases a cause for the encephalopathy is readily identifiable,whilst in a minority the aetiology is more difficult to ascertain. Frequently the onset of encephalopathy is associated with, or follows, infection. The mechanisms through which infection leads to encephalopathy are diverse. They range from direct microbial invasion of the brain or its supporting structures, to remote, infection-triggered mechanisms such as acute disseminated encephalomyelitis. Most common however, is the encephalopathy caused through a remote effect of systemic sepsis-septic encephalopathy. This article discusses the clinical presentation and underlying pathogeneses of the acute encephalopathies associated with infection, aiming to aid both their recognition and treatment.

Devastating epileptic encephalopathy in school-aged children (DESC): A pseudo encephalitis

PURPOSE

To describe the characteristics of a previously overlooked devastating epileptic encephalopathy that presents as intractable bilateral perisylvian epilepsy starting with prolonged status epilepticus (SE) in normally developing school-aged children.

METHODS

Retrospective study over 7 years of all normally developing children admitted in our institution for a prolonged SE following non-specific febrile illness with at least one seizure recorded on EEG.

RESULTS

Fourteen children were included at a median age of 7.5 years (4-11) (median follow-up of 4 years (1-7)). Intractable SE lasted 4-60 days (median 30). CSF cell count was normal in five cases and moderately increased in the others. During SE, seizures were recorded in 11 patients and involved temporal lobes in 7; the other 4 patients exhibited perisylvian clinical features with secondary generalization. Intractable epilepsy followed SE in all cases without any latent period. Persisting seizures were recorded in 10 patients and involved temporo-perisylvian regions in 8, frontal regions in 2; 3 others had perisylvian ictal semiology. Spiking was bilateral in 10 cases. MRI showed bilateral hippocampal hypersignal and/or atrophy in 10 cases (extended to the neocortex in 3). All children had major cognitive sequelae. When feasible (six patients), detailed neuropsychology suggested fronto-temporal impairment.

CONCLUSIONS

Among so called grey matter encephalitis patients, we identified a recognizable pattern we propose to call Devastating Epileptic encephalopathy in School-age Children (DESC) that begins with prolonged SE triggered by fever of unknown cause, and persists as intractable perisylvian epilepsy with severe cognitive deterioration.

Optic neuropathy: puls/minus

A 26-year-old Asian woman presented with bilateral disk swelling, retinal exudates and infarcts. Evaluation found the underlying cause of the hypertensive optic neuropathy to be renal artery stenosis due to Takayasu's arteritis.

Acute disseminated encephalomyelitis

Acute disseminated encephalomyelitis (ADEM) is a monophasic inflammatory disorder of the central nervous system (CNS). Unlike viral encephalitis, microorganisms do not invade the CNS. Instead, ADEM is a postinfectious disease mediated by auto-reactive cells or molecules. Clinical characteristics of ADEM are consistent with disseminated involvement of the CNS, including encephalopathy and pyramidal, cerebellar, and brainstem signs. Bilateral optic neuritis and transverse myelitis are particularly suggestive of demyelinating diseases such as ADEM. Unlike viral encephalitis, seizures rarely are a prominent symptom. The most useful diagnostic investigation is magnetic resonance neuroimaging that commonly shows multifocal lesions throughout the brain and spinal cord. As ADEM is an immune-mediated disorder, treatment includes immunomodulatory therapies (particularly steroids), although no clinical trials have been performed to define the most efficacious agent. In view of the treatment differences between ADEM and viral encephalitis, being familiar with ADEM is essential for pediatricians managing acute neurological disorders.

Acute encephalitis from 1967 to 1991

We studied all the adult patients with acute encephalitis, 322 in all, in the Helsinki area, Finland, during the years 1967--1991. The average incidence was 1.4/100000 adults/year. The proportion of known and suggested etiologies in 5-year periods has risen from 36 (1967--71) to 59% (1987--91). Herpes simplex virus was identified most often (16%), followed by varicella-zoster (5%), mumps (4%), and influenza A viruses (4%). In addition, 20 other agents were identified. The leading cause of encephalitis in patients aged 65 years or more was varicella-zoster virus. Eighteen patients (5.6%) died. It appears that the etiology of encephalitis changes with age and with time. It is important to establish the etiological pattern, as this assists in prompt diagnosis, which is a prerequisite for successful therapy.

Cognitive outcome in acute sporadic encephalitis

Acute encephalitis is an inflammation of the brain parenchyma. In the United States, 20,000 cases occur yearly. A variety of cognitive deficits, often the sole cause of disability, may persist after the acute stage. Still, infectious diseases tend to be covered only briefly in neuropsychological handbooks. Recent literature demonstrates the heterogeneity of both amnestic disorders and the outcome following encephalitides. Herpes Simplex virus (HSV), the most common single etiology of sporadic encephalitis, usually causes the most severe symptoms. Modern antiviral medication, however, seems to improve the cognitive outcome. Much less is known about non-HSV encephalitides, where both mild and severe defects have been observed. This article summarizes the current knowledge and also calls upon a more active neuropsychological research in the area.

ADEM: literature review and case report of acute psychosis presentation

Acute disseminated encephalomyelitis is a monophasic, immune-mediated disorder that produces multifocal demyelinating lesions within the central nervous system. It is characterized clinically by the acute onset of neurologic abnormalities, including varying degrees of mental state changes ranging from drowsiness to coma. It is unusual for the illness to present as an isolated acute psychosis. The case of a 14-year-old female with biopsy-confirmed acute disseminated encephalomyelitis, who was initially diagnosed with an acute psychiatric disorder, is presented, and published reports on this unusual manifestation are reviewed. A Medline database search was performed from 1965 to 1999, using the terms acute disseminated encephalomyelitis, postvaccinal encephalomyelitis, postinfectious encephalomyelitis, and measles encephalomyelitis, combined with the terms psychosis, psychiatric disorder, and behavioral disorder. Selected cross-referenced reports were also reviewed. Nine patients were identified who presented with acute psychosis. We conclude that, although rare, acute disseminated encephalomyelitis can present as an acute psychosis. This immune-mediated condition should be included in the differential diagnosis of neurologic disorders presenting as a psychiatric illness.

Dopaminergic therapy in acute encephalitis lethargica

We describe a patient with an acute illness, with clinical features characteristic of encephalitis lethargica, who responded repeatedly to trials of an apomorphine infusion and subsequently to oral levodopa therapy. This observation implies a direct acute neurotropic effect of the encephalitis on nigral dopaminergic cells. Dopaminergic medication may therefore be helpful in the acute stage of encephalitis lethargica as well as in the delayed post-encephalitic parkinsonian phase of the syndrome.

Acute viral encephalitis in adults--a prospective study

We have prospectively studied 27 adult patients attending the Department of Infectious Diseases, Göteborg, Sweden, between October 1992 and October 1996 with a diagnosis of acute viral encephalitis. In addition to cerebrospinal fluid (CSF) virus isolations and antibody analyses against herpes simplex virus, cytomegalovirus, varicella zoster virus, Epstein-Barr virus (EBV), enterovirus, adenovirus, tick-borne encephalitis virus, and mycoplasma, polymerase chain reaction test (PCR) to 5 viruses from the family of human herpes viridae, and to adenovirus as well as to enterovirus were analysed in CSF. 10 patients had herpes simplex virus type-1 (HSV-1), 1 had varicella zoster virus, 1 had tick-borne encephalitis, and 2 had Influenza A infections. In 13 patients the aetiology remained unclear. Eight patients with HSV-1 encephalitis and clinical symptoms for 2-11 d before admission were PCR-positive, while 2 patients with a < or = 2 d history of disease were negative for HSV-1 DNA on admission. These 2 patients became positive for HSV-1 DNA in CSF samples taken 4 d later in 1 case and 7 d later in the other. In 4 patients with HSV-1 encephalitis, in 1 patient with Influenza A complicated by encephalitis, and in 1 patient with encephalitis of unknown origin EBV DNA was found in CSF samples during the study. The clinical significance of these findings is unclear. The study shows that HSV-1 was the most common etiological agent in patients with viral encephalitis in the Göteborg area. In spite of improved diagnostic procedures, a large proportion of patients with symptoms and laboratory findings compatible with viral encephalitis still have an unclear aetiology.

Cognitive recovery instead of decline after acute encephalitis: a prospective follow up study

OBJECTIVE

Follow up of cognitive sequelae of acute encephalitis and estimation of the frequency of persisting dementia.

METHODS

Out of a series of 45 consecutive patients with acute encephalitis prospectively studied in 1990-95, 40 were screened for difficulty in everyday life using the Blessed dementia scale (BDS) 3.7 (1.4), mean (SD), years after onset. Eight patients had had herpes simplex encephalitis (HSVE), 16 some other identified aetiology, and in 21 the aetiology was unknown. All, except two patients with a nonherpetic encephalitis, were treated with acyclovir. All patients with disability in BDS (12/40), were invited to a neuropsychological reassessment, and the results of this assessment were compared with those of a similar assessment done after the acute stage. At follow up one patient could not complete the tests due to intractable epilepsy.

RESULTS

In six of 11 cases the symptoms causing disability were mainly psychiatric. Five patients (two with HSVE) had a pronounced memory impairment together with other cognitive deficits, indicating dementia (frequency of 12.8%). In eight of the 11 testable cases cognitive performance had improved over the years, in two cases a decline was found and one patient with severe deficits showed no change. Intractable epilepsy was found in four of 12 cases.

CONCLUSION

Cognitive decline had taken place already at the acute stage, and further deterioration was uncommon. Considerable improvement occurred in most patients during follow up. Also in patients with HSVE treated with acyclovir the cognitive recovery was substantial and of a magnitude not expected based on previous literature. Intractable epilepsy contributed to the cognitive deterioration in some cases. Affective disorders also had a surprisingly important role for the long term outcome.

Cognitive impairment after acute encephalitis: comparison of herpes simplex and other aetiologies

OBJECTIVE

To compare the cognitive defects after acute acyclovir treated herpes simplex encephalitis with those after other types of acute encephalitis.

METHODS

Seventy seven consecutive patients between 1985 and 1995 and 29 normal controls were studied. Of the 77 patients without concomitant neurological conditions, 17 had herpes simplex, one virus encephalitis (HSVE group), 27 had some other identified aetiology (non-HSVE group), and in 33 patients the cause was unknown. Acyclovir treatment was started less than four days after the first mental symptoms in 12 of 17 patients with HSVE. A thorough neuropsychological assessment was carried out about one month after the onset.

RESULTS

The HSVE group had deficits in verbal memory, verbal-semantic functions, and visuoperceptual functions more often than the non-HSVE group. The risk for cognitive defects was twofold to four-fold in the patients with HSVE compared with the non-HSVE patients. Two (12%) of the patients with HSVE and 12 (44%) of the non-HSVE patients were cognitively intact. Six patients with HSVE (46%) and 17 (89%) non-HSVE patients later returned to work. The lesions on CT or MRI were bilateral only in one patient with HSVE. The defects in the three patients with adenovirus infection were severe and resembled the amnesia after HSVE. Cognitive impairment, not previously reported, was found in encephalitis after rotavirus infection and epidemic nephropathy.

CONCLUSION

The recovery in the HSVE group was better than expected based on the medical literature. On the other hand there were surprisingly severe cognitive defects in encephalitis after other viruses. With early acyclovir treatment patients with the least severe HSVE were equivalent to those with non-HSV encephalitis with good outcome whereas those with the most severe non-HSV encephalitis were equivalent to those with HSVE with poor outcome.

Acute manifestations and neurologic sequelae of Epstein-Barr virus encephalitis in children

BACKGROUND

Complications of Epstein-Barr virus (EBV) infection are diverse and include a number of neurologic manifestations such as meningitis, meningoencephalitis, cerebellitis, cranial neuritis and others. In general encephalitis caused by EBV in pediatric patients has been considered a self-limited illness with few or no sequelae.

METHODS

Charts were reviewed from all patients < 18 years of age admitted to or discharged from the State University of New York Health Science Center at Syracuse between 1982 and 1992 with a diagnosis of encephalitis or meningo-encephalitis. Eleven cases of EBV encephalitis diagnosed during a 10-year period were reviewed to characterize the clinical and laboratory findings in the acute setting and the extent of neurologic sequelae on follow-up.

RESULTS

Acute neurologic manifestations were diverse and included combative behavior (55%), seizures (36%), headache (36%) and evidence of focal involvement (27%). Classic findings of infectious mononucleosis were noted infrequently; 18% each had pharyngitis, adenopathy, positive heterophile antibody tests or atypical lymphocytosis. Two patients (18%) had abnormal neuroimaging studies, one in the acute stage and the other at the time of follow-up. Seven patients (64%) had abnormal electroencephalograms (EEGs) in the acute setting; of these three had persistent abnormalities on follow-up. Forty percent developed persistent neurologic abnormalities including global impairment, perseverative autistic-like behavior and persistent left upper extremity paresis.

CONCLUSIONS

Classic signs, symptoms and laboratory findings in infectious mononucleosis may be absent in Epstein-Barr virus encephalitis. Neurologic sequelae occur in a substantial number of patients.

Fever in neurologic diseases

In the sense that the brain houses the central mechanism for the regulation of body temperature, almost all illnesses that cause fever must interact with the central nervous system. There are far fewer diseases, however, in which the nervous system symptomatology is of prime diagnostic importance. A helpful way to view fever in association with neurologic disease is to roughly divide these disease entities into four broad categories: (1) neurologic impairment resulting from fever itself, (2) fever as the sole manifestation of a central nervous system infection, (3) systemic febrile disorders with central nervous system signs and symptoms, and (4) primary neurologic diseases, either central or peripheral in origin, with fever as a presenting sign. This article discusses the clinical presentation of disorders in each of these categories as an aid to the clinician in diagnosing and differentiating between these syndromes.

Acute encephalitis

Acute encephalitis: etiology, clinical findings and prognosis. We studied 44 patients with acute encephalitis diagnosed in a neurological university clinic during an 11-year period. An etiology was found in 11 cases (25%). In 3 the cause was herpes simplex virus; in 2 morbilli. There were single patients in which the cause was mycoplasma pneumoniae, epidemic parotitis, ornithosis, infectious mononucleosis, influenza B-virus and recent tetanus immunization. No specific etiology was found in 33 (75%). Besides fever the most frequent sign was impairment of consciousness in 39% of cases. Four patients (9%) died. Among the survivors mental and/or focal neurological deficits persisted in 22 (55%). Most frequent was dementia in 6 cases (15% of survivors). Impaired consciousness in the acute phase indicated a worse prognosis (p < 0.005).

Predictive factors of short-term neurologic outcome in children with encephalitis

When a child is admitted to the hospital with presumed encephalitis, the physician must use clinical criteria to gauge the appropriate level of hospital care and to give a preliminary assessment of outcome to the family because the etiology is unknown. This study attempted to determine which clinical factors gathered on hospital admission would be most helpful to the physician. The records of 106 children (ages 1 month to 20 years), admitted to Rainbow Babies and Childrens Hospital between 1978-1989 who had discharge diagnoses of encephalitis, were reviewed. Seventy-five met the case definition of presumed viral encephalitis, with viral etiology established in 23% of patients. Poor short-term outcome was defined as the presence of an abnormal neurologic examination at hospital discharge, and was present in 32% of patients. Focal signs on neurologic examination (odds risk: 16.30, P < .05) and abnormal neuroimaging studies (odds risk: 5.66, P < .05) were the only 2 factors present at admission that predicted a poor short-term outcome. Glasgow coma scale at admission was predictive of an abnormal neurologic examination at discharge only when profoundly depressed (6 or less); otherwise, this scale was not useful as a prognostic tool. Factors that were not correlated with adverse outcomes included age younger than 1 year, any type of seizure occurrence, status epilepticus, diffuse or focal electroencephalographic abnormalities, or abnormal cerebrospinal fluid findings.(ABSTRACT TRUNCATED AT 250 WORDS)

Neurologic complications of infectious mononucleosis

A review of the neurologic complications of Epstein-Barr viral (EBV) infections is presented. EBV has been associated with a wide range of acute neurologic diseases in children. Encephalitis, meningitis, cranial nerve palsies, mononeuropathies, and many other neurologic ailments have been described since the confirmation of EBV as the etiology of infectious mononucleosis. It is important to recognize that EBV can cause a myriad of neurologic illnesses with or without the stigmata of infectious mononucleosis.

Epidemiology of acute childhood encephalitis. Aichi Prefecture, Japan, 1984-90

The case records for 256 patients with acute encephalitis, including meningoencephalitis, acute encephalopathy and Reye syndrome, were obtained from 36 departments of pediatrics in large hospitals through questionnaires which were sent in 1990-92. The incidence rate per 100,000 child years was 3.3, and was more frequent in children aged 0-4 years (rate 6.6) than 5-15 years (rate 2.0), with statistical significance. The disease in the 105 etiologically diagnosed patients was due to measles virus (24), herpes simplex (21), rubella (24), and other agents (36), including two cases of human herpesvirus 6. A third of the infants with measles encephalitis were first seen at less than 18 months of age. Eighteen cases of rubella encephalitis occurred during an epidemic of rubella in Aichi Prefecture, 1987-88. The short-term outcome (mean length of follow-up: 2 years 3 months) of encephalitis was death in 20 cases (7.8%) and sequelae in 58 (24%). Eleven patients died within 7 days and five by the 8-14th day from onset. Thirty-six children had multiple residual impairments, including twelve who were severely handicapped. The prognosis for both life and sequelae was significantly poor for herpes simplex encephalitis in etiologically diagnosed patients. We stress the importance of an increase in the vaccination rate and the establishment of an early diagnostic system.

Encephalitis lethargica-like illness in a five-year-old

A five-year-old boy presented with an encephalitis lethargica-like illness, characterised by somnolence, mutism and Parkinsonian rigidity two weeks after an acute exanthem. Investigation revealed increased serum measles antibody titre. He made a complete recovery. Encephalitis lethargica associated with Parkinsonism in childhood is rare and usually carries a poor prognosis.

Cerebellar syndrome with hydrocephalus due to Mycoplasma pneumoniae infection

A 27 year old woman developed a cerebellar syndrome with serological evidence of recent Mycoplasma pneumoniae infection. The cranial computed tomographic scan showed effacement of the fourth ventricle, enhancement of the basal meninges and hydrocephalus affecting the lateral and third ventricles. Clinical and radiological recovery occurred over 5 weeks. We propose that this was a manifestation of immune-mediated encephalomyelitis induced by the infection rather than direct invasion of the central nervous system.

Clinical and electroencephalographic studies of postencephalitic epilepsy

We retrospectively reviewed the clinical features and results of investigation of 62 patients with acute encephalitis or encephalopathy in the acute phase to identify the prognostic factors in the development of postencephalitic epilepsy. Patients who later developed epilepsy showed more marked disturbance of consciousness, convulsions, and seizure activities on EEG during the acute phase than those who did not. There was no relation between CSF abnormalities and postencephalitic epilepsy. Control of convulsions during the acute phase, especially of status epilepticus, seems to be important to improve the prognosis.

Demonstration of zoster virus antibodies in cerebrospinal fluid cells

A method is presented that allows the immunocytochemical detection of varicella zoster virus antigen-binding cerebrospinal fluid cells in zoster ganglionitis. Antigen-binding cells were found only in patients suffering from this disease. The technique is sensitive, specific, inexpensive and relatively fast, and is potentially applicable to other inflammatory central nervous system diseases with immunoglobulin-containing cells (ICC) in CSF. The detection of antigen-binding CSF cells may represent a very early diagnostic test comparable with the early IgM antibodies of the systemic immune response.

The prognosis and long-term course of viral encephalitis

Of 33 patients with viral encephalitis, four (three women, one man) succumbed to the disease. Of the surviving patients, 23 were followed for a median interval of 4 years after discharge. A considerable residual syndrome could be detected in two cases only. The outcome was determined by identification of causative organism (especially herpes simplex virus), initial consciousness disturbances and pleocytosis in the cerebrospinal fluid. On the other hand, the age of the patients, electroencephalographic findings and a symptomatic epilepsy played no major role. Without confirmed virus findings, immunoglobulins were as effective as the virostatic therapy regimens; with identification of causative organism, combined treatment with acyclovir and immunoglobulins was most effective.

Computed tomographic findings in acute viral encephalitis in adults with emphasis on herpes simplex encephalitis

Nine patients with acute viral encephalitis were diagnosed by CT. Seven had herpes simplex and two had nonherpetic acute viral encephalitis. All patients with herpes simplex encephalitis initially were febrile. They developed confusion and seizures. Five had focal neurological deficit and two had papilledema. The CT scan showed an abnormality on the initial CT in 6 of 7 cases. In one case initial CT study was normal; however follow-up scan (performed 5 days later) showed a definite abnormality. CT showed the characteristic pattern of herpes simplex encephalitis in all cases. This is a temporal lobe hypodense lesion (unilateral, 5 cases; bilateral, 2 cases) with a small interspersed hyperdense region. The hyperdense component represents hemorrhage. Mass effect was seen in all cases. Two patients showed enhancement which was diffuse or patchy in one case and cisternal-gyral in the other; however enhancement was absent in 5 cases. One patient showed progression of the size of the hypodense lesion despite antiviral treatment. Follow-up CT showed hypodense lesion(s) in the temporal lobe region with enlargement of the temporal horns and contiguous basal cisterns in 4 cases. In 2 other cases of acute viral encephalitis the patients initially developed fever, confusion and seizures. CT showed basal ganglia calcification or hypodense lesions.

Herpes simplex virus encephalitis in children

Herpes simplex encephalitis (HSE) is an uncommon disease, yet 25 to 30 per cent of cases involve children. The initial clinical findings are nonspecific (fever, altered mental status), but most cases evolve to demonstrate focal neurologic signs and symptoms. The CSF is abnormal in over 90 per cent of cases. The EEG, CT, and MRI will further help in detecting focal encephalitis. The clinician caring for a child with focal encephalitis should institute broad-spectrum antimicrobial therapy plus acyclovir, pending definitive diagnosis by ancillary tests or brain biopsy, which is positive for HSE 33 to 55 per cent of the time and is diagnostic for other treatable conditions 10 to 20 per cent of the time. Acyclovir is the drug of choice for HSE and substantially reduces mortality and morbidity. The management of HSE in a child requires an experienced team of specialists and laboratory support in a tertiary intensive care setting.

Clinical predictors of outcome in encephalitis

Twenty five patients with encephalitis were studied prospectively, and their clinical and virological features compared with outcome. Among 22 patients with laboratory confirmation of virus infection, evidence of direct effect on the central nervous system by the virus occurred significantly more often both in those with a monophasic illness compared with those with a biphasic illness, and in those with focal neurological signs localising in the cerebral hemispheres compared with those without such signs. Young age at presentation, low score on the Glasgow coma scale, disruption of oculocephalic responses, and laboratory evidence of virus infection within the central nervous system were significantly associated with poor outcome. Computed tomography results, concentrations of creatine phosphokinase BB isoenzyme in cerebrospinal fluid, and procoagulant activity in cerebrospinal fluid were not predictive of outcome.

The pathogenesis of virus-associated encephalopathies: a prospective study of immunological mechanisms

Thirty-two patients, including 29 children, presenting with acute unexplained encephalopathies were studied prospectively for evidence of virus infection, immunodeficiency, and immunologic involvement in the pathogenesis of their illnesses. Twenty-five of these patients had a clinical diagnosis of encephalitis. Twenty-two of these 25 had laboratory evidence of active virus infection, the majority with viruses usually associated with self-limiting illness outside the central nervous system. In patients with encephalitis, immune competence, as reflected by T-cell numbers and subsets in peripheral blood, in vitro interferon production, natural killer activity, and specific antiviral antibody production, was normal. Transudation of albumin into the cerebrospinal fluid (CSF), a measure of blood-brain barrier breakdown, was seen in 40% of patients. Intrathecal antibody synthesis was suggested by an elevated IgG index in 9/20 CSF/serum pairs but was confirmed by an elevated specific IgG ratio in only 3. The serum IgG1 and IgG3 subclass levels were significantly elevated at the time of the illness and remained elevated 8 months later; IgG2 and IgG4 levels were normal. IgE levels were elevated in 50% of patients. Serum levels of IgM antibodies against Escherichia coli measured 8 months after the neurological illness were also significantly higher in encephalitis patients than in age-matched healthy controls. Human myelin basic protein did not induce proliferation in peripheral blood lymphocytes in any patient. We conclude that most encephalopathies associated with viral infections are not due to an underlying generalized immunodeficiency, and probably result from an inappropriately vigorous immune response.

Non-herpes simplex encephalitis is early exclusion of herpes simplex etiology possible?

Since effective antiviral treatment is available for herpes simplex encephalitis (HSE), early diagnosis or exclusion of herpes simplex etiology is essential for prognosis. In a retrospective study of 25 cases of acute viral encephalitis not caused by herpes simplex virus (non-HSE), we investigated whether HSE can be excluded in the early phase before serological evidence is present. Using clinical means, history, investigations of CSF (protein, cells), EEG, and CCT, HSE could not be excluded with reliability. This is because clinical signs and laboratory results are not pathognomonic for any form of viral encephalitis, even if periodic activity in EEG and temporal attenuation in CCT are more frequent in HSE than in other forms of encephalitis. Therefore, in all cases of severe encephalitis, acyclovir therapy should be initiated early.

MRI of mumps encephalitis: comparison with CT evaluation

The evaluation of a patient with mumps encephalitis by computed tomography (CT) and magnetic resonance (MR) imaging is reported. Correlation of findings on MR and CT in relation to clinical symptoms is presented. MR was found to be more sensitive in the number of lesions detected (11) as compared to CT (3). Thus, it seems that MR imaging may be a sensitive diagnostic adjunct in cases of suspected viral encephalitis.

Influenza virus-induced encephalopathy in mice: interferon production and natural killer cell activity during acute infection

Mice injected intracerebrally with infectious influenza virus (60 hemagglutinin units) developed lethargy, seizures, comas, and died 2 to 5 days postinfection. As early as 6 h after infection, the cerebrospinal fluid (CSF) in these animals was infiltrated with polymorphonuclear cells, mononuclear leukocytes, and large granular lymphocytes. Potent natural killer (NK) cell activity was observed for both CSF and spleen cell populations over the same period. This NK cell activity correlated with interferon (IFN) levels in the CSF and serum. Treatment of lethally infected mice with either anti-IFN alpha-IFN beta or anti-ganglio-n-tetraoglyceramide antiserum ameliorated the disease, reduced mortality, and effected changes in the relative proportions of inflammatory cell populations infiltrating the CSF. The possible significance of IFN and NK cell activity in the development of this influenza virus-induced encephalopathy is discussed.

A major role for viruses in acute childhood encephalopathy

29 children and 3 adults with acute depression of conscious level or acute onset of focal neurological signs were studied prospectively. 3 were found to have a non-infectious cause for their illness. The presence of interferon or specific antibodies in the serum and/or cerebrospinal fluid provided evidence of active virus infection in 25 of the remaining 29 patients. There was laboratory evidence that a virus had invaded the central nervous system in 11 patients. Early investigation gave the highest diagnostic yield. Since several common viruses were identified, it appears that the nature of the illness is due more to the host response than to the nature of the infective agent.

Acute disseminated encephalitis documented by magnetic resonance imaging and computed tomography. Report of a case

A 16-year-old girl developed left hemispheric deficits, which were followed by clouding of consciousness, quadriplegia, and subcortical blindness. Although we could not demonstrate a recent viral infection, the clinical features, laboratory and radiologic findings strongly suggested the diagnosis acute disseminated encephalitis. Cerebrospinal fluid abnormalities incompletely correlated with the clinical course. In contrast, X-ray computed tomography and particularly magnetic resonance imaging of the head closely reflected disease and improvement.

Acute viral encephalitis

Clinical manifestations of acute viral encephalitis are described, differential diagnoses are outlined, and a diagnostic approach is recommended. Encephalitic syndromes caused by arboviruses, herpesviruses, enteroviruses, and parainfectious processes are discussed.

Use of enzyme-labeled antigen for the detection of immunoglobulin M and A antibody to herpes simplex virus in serum and cerebrospinal fluid

A direct enzyme-linked immunosorbent assay (ELISA that used peroxidase-labeled antigen) was developed for detection of IgM and IgA antibody to herpes simplex virus (HSV). The assay uses immuno-affinity-purified antihuman IgM or IgA antibody-coated wells of microtiter plates to separate IgM or IgA from other classes of antibody in serum or cerebrospinal fluid (CSF). The presence of specific IgM or IgA is detected by subsequent, consecutive incubation with peroxidase-labeled antigen and substrate. HSV antigen was purified by sucrose gradient centrifugation and coupled with peroxidase by the periodate method. By examining sucrose-gradient-fractionated sera the assays were shown to be specific for IgM and IgA classes of antibody. None of the sera from patients with Epstein-Barr virus (n = 20), cytomegalovirus (n = 20), or varicella-zoster virus (n = 8) infection or with both rheumatoid factor and IgG antibody to HSV (n = 13) reacted positively. Only one out of 78 sera from healthy persons was positive for IgA antibody to HSV, and none for IgM antibody. All 33 patients with HSV infection developed HSV-IgA, 22 developed HSV-IgM. Of the 11 patients with primary infection, all had IgM antibody in their first sera and six had IgA antibody. The corresponding figures for the 22 patients with recurrent infection were five and nine. Furthermore, HSV-IgA antibody was found in serum and CSF of all five patients with HSV encephalitis in the second week after onset of symptoms, indicating the usefulness of the assay as a noninvasive technique for diagnosing HSV encephalitis.

Encephalitis and aseptic meningitis, Olmsted County, Minnesota, 1950-1981: I. Epidemiology

All cases fulfilling stated criteria for encephalitis and aseptic meningitis in Olmsted County, Minnesota, for the period 1950 through 1981 were identified. This is, to our knowledge, the first such incidence and trend study in a delineated population, providing rates per 100,000 person-years of 7.4 for encephalitis (189 cases) and 10.9 for aseptic meningitis (283 cases). These are about twelve and six times higher, respectively, than the rates reported by the Centers for Disease Control. The rates have been stable over successive 5- or 10-year periods except for a recent increase in aseptic meningitis. Both conditions were more common in the summer months, in childhood, and among males. Viral identification using conventional laboratory tests has improved with time; in the period 1970 through 1981, virus type was specified in about one-fourth of the cases. The most common agents identified were California and mumps viruses in encephalitis, and entero and mumps viruses in aseptic meningitis. Antecedent and/or concurrent infections were noted in 42 and 35% of encephalitis and aseptic meningitis cases, respectively. No case due to mumps, measles, or rubella viruses has occurred since 1972, reflecting the impact of immunizations. Recovery was reported at the end of the acute phase in 95% of patients with aseptic meningitis, and there were no deaths. Seventy-eight percent of encephalitis patients recovered completely; the case fatality rate was 3.8%. Of the encephalitis cases, 2% were diagnosed initially postmortem.