Cause Of Infectious Encephalitis Research Articles

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

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. 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. 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). 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. The Policy Research Programme, Department of Health, UK.

Role of Mycoplasma pneumoniae in pediatric encephalitis

A retrospective study investigating all the infectious encephalitis cases hospitalized at the pediatric intensive care unit of Edouard Herriot University Hospital in Lyon, France, was carried out in order to estimate the prevalence of Mycoplasma pneumoniae in acute childhood encephalitis. From January 2001 to December 2005, the cases of 29 children were selected and reviewed. M. pneumoniae related encephalitis was considered as probable in five cases (17%) on the basis of positive serological tests or positive polymerase chain reaction (PCR) tests in throat or nasopharyngeal swab while the PCR tests performed from the cerebrospinal fluid were negative. This study suggests that M. pneumoniae may be a major cause of infectious encephalitis in children as well as enteroviruses or Epstein-Barr virus detected in five and three cases, respectively.

West Nile viral encephalitis mimicking hepatic encephalopathy

West Nile encephalitis (WNE) has become endemic in the United States since 1999. The clinical spectrum of WNE includes aseptic meningitis, meningoencephalitis, or encephalitis with or without flaccid paralysis. The severity of WNE ranges from asymptomatic serum conversion to severe neurologic deficits or a fatal outcome. Several systemic disorders may present with encephalitis as part of the clinical presentation, for example, Legionnaires' disease, neoplasms with metastases to the central nervous system, Mycoplasma meningoencephalitis, brucellosis, Listeria, Rocky Mountain spotted fever, ehrlichiosis, and malaria. The most common infectious causes of encephalitis that need to be differentiated from WNE include herpes simplex virus 1, meningoencephalitis, and enteroviral meningoencephalitis. We present a case of apparent hepatic encephalopathy secondary to pancreatic carcinoma with liver involvement that presented as hepatic encephalopathy mimicking WNE. We conclude that patients presenting with encephalitis in the summer months should have serum/cerebrospinal fluid serologic studies sent for WNE even if an alternate explanation seems to explain the clinical syndrome.

Hematoma cerebral en el curso de una encefalitis herpética

Herpes simplex encephalitis (HSE) is the most common cause of infectious encephalitis at all ages. The usual presentation includes a high temperature, headache and confusion associated with convulsions and signs of a focal neurological deficiency. The typical findings shown by magnetic resonance imaging (MRI) consist of hyperintense lesions, in T2 and FLAIR sequences, especially in the medial and inferior temporal lobe. AIMS. The aim of this paper is to report a case of HSE that associated a cerebral haematoma (CH) in its clinical course. A 69 year old female patient who was admitted to hospital because of a syndrome of high temperature, confusion and urinary infection. Studies of the cerebrospinal fluid showed only a slight pleocytosis, and a polymerase chain reaction (PCR) for the herpes simplex virus (HSV) was required. Initial MRI scanning showed an image that was compatible with cerebritis in the left parieto occipital lobe. A later RMI scan revealed a cerebral haematoma in the left parieto occipital lobe, together with new haemorrhagic foci in the bifrontal and in the right temporal lobes. The haematoma was drained surgically and empirical therapy was begun with acyclovir, and later a positive HSV PCR was received. The patient responded favourably to the therapy and was discharged from hospital. A variety of atypical presentations in HSE have been reported. Our case presented scant pleocytosis, infrequent lesion topography and coursed with CH. Only a few cases of this last occurrence have been reported in the literature. The presence of infrequent features, such as CH, within the framework of the clinical features of encephalopathy cannot exclude the possible existence of HSE.

DIAGNOSIS AND TREATMENT OF ACUTE ENCEPHALITIS

BACKGROUND Encephalitis is the second most common type of infection of the central nervous system and continues to be an important cause of mortality and morbidity. REVIEW SUMMARY In a patient who is suspected of having encephalitis, one must distinguish between encephalitis and encephalopathy and between infectious encephalitis and acute disseminated encephalomyelitis. Once infectious encephalitis has been diagnosed, one should determine whether the patient has herpes simplex encephalitis, because treatment with antiviral drugs such as acyclovir greatly improve outcome. Most cases of infectious encephalitis are due to viruses, but bacteria, fungi, and parasites also can be the cause, especially in immunosuppressed individuals. The rapid determination of the cause of infectious encephalitis remains difficult, but newer assays to detect IgM antibody to the infectious agent in CSF or serum and polymerase chain reaction assays for nucleic acid fragments of the infectious agent in CSF are enabling faster and more accurate diagnoses. Antimicrobial drugs now are available for many of the infectious agents and some DNA viruses, but excellent treatment of the patient's symptoms remains very important. CONCLUSIONS This review provides an approach to diagnosing possible encephalitis through asking and answering several key questions. Recent advances in methods of determining the cause of the encephalitis and better antimicrobial drugs improve the likelihood of successful treatment. CONCLUSIONS (THE NEUROLOGIST 6:145-159, 2000)