VIRAL ENCEPHALITIS James M. Mitchell, M.D.

VIRAL ENCEPHALITIS OBJECTIVES DEFINE VIRAL ENCEPHALITIS UNDERSTAND ETIOLOGY AND EPIDEMIOLOGY UNDERSTAND THE CLINICAL PRESENTATION DIFFERENTIAL DIAGNOSIS DIAGNOSTIC WORKUP TREATMENT OPTIONS PREVENTIVE MEASURES

VIRAL ENCEPHALITIS DEFINITIONS VIRAL (ASEPTIC) MENINGITIS ENCEPHALITIS MENINGOENCEPHALITIS MYELITIS CEREBRITIS ENCEPHALOMYELITIS

VIRAL ENCEPHALITIS VIRAL MENINGITIS “ …usually a self-limited illness characterized by signs of meningeal irritation, such as headache, photophobia, and neck stiffness.”1

VIRAL ENCEPHALITIS ENCEPHALITIS “ …entails involvement of parenchymal brain tissue as indicated by convulsive seizures, alterations in the state of consciousness, and focal neurological abnormalities.”1

VIRAL ENCEPHALITIS MENINGOENCEPHALITIS “…both meningeal and encephalitic findings are present.”1

VIRAL ENCEPHALITIS MYELITIS “infection of parenchyma of the spinal cord …may occur from infection of spinal motor neurons (paralytic disease, poliomyelitis), sensory neurons, autonomic neurons (bladder paralysis), or demyelination of white matter (transverse myelitis).”1

VIRAL ENCEPHALITIS CEREBRITIS “…an acute inflammatory reaction and regional edema…describes the stage preceding abscess formation and implies a highly destructive bacterial infection of brain tissue.” 2,3

VIRAL ENCEPHALITIS INTRODUCTION TWO FORMS Primary encephalitis- occurs when the virus directly invades the brain: herpes simplex, varicella-zoster, arboviruses, Epstein-Barr Secondary (post-infectious) encephalitis- are immune-mediated processes which result in multifocal demyelination of perivenous white matter: rubeola, mumps, rubella, CMV

VIRAL ENCEPHALITIS INTRODUCTION Acute Chronic Herpes simplex encephalitis Varicella-zoster encephalitis Epstein-Barr Arboviral encephalitides Chronic Subacute sclerosing panencephalitis Progressive rubella panencephalitis HIV HTLV-1 Progressive multifocal leukoencephalopathy Prion diseases- Kuru, Creutzfeldt-Jakob

VIRAL ENCEPHALITIS ETIOLOGY Primary encephalitis- acute DNA viruses RNA viruses

VIRAL ENCEPHALITIS DNA VIRUSES Herpes simplex (HSV) Varicella-zoster (VZV) Cytomegalovirus (CMV) Epstein-Barr (EBV) Papovavirus (PML) Adenovirus

VIRAL ENCEPHALITIS RNA VIRUSES Arboviruses Alphaviruses: Equine Encephalitis (Eastern, Western, Venezuelan) Flaviviruses: St. Louis Encephalitis, Japanese Encephalitis, West Nile Encephalitis, Tick-borne Encephalitis Bunyavirus: La Crosse Encephalitis Orbivirus: Colorado Tick Fever

VIRAL ENCEPHALITIS RNA VIRUSES Paramyxoviruses: mumps, measles Enteroviriuses: poliovirus, coxsackie, enterovirus 70/71 Togavirus- rubella Rhabdovirus: rabies Retroviruses: HIV, HTLV Orthomyxovirus: Influenza Arenavirus: Lymphocytic Choriomeningitis

VIRAL ENCEPHALITIS EPIDEMIOLOGY HSV- Varicella-zoster- Measles- Most common cause of sporadic encephalitis in western countries, incidence 0.2/100,000 (neonatal HSV infection occurs in 2-3/10,000) Varicella-zoster- Tends to be mild, incidence of 1/2000 infected persons Measles- Two forms Postinfectious , incidence 1/1000 Subacute sclerosing panencephalitis, incidence 1/100,000

VIRAL ENCEPHALITIS EPIDEMIOLOGY Arboviruses- The most common causes of episodic encephalitis, incidence similar to that of HSV All require an insect vector: mosquito, ticks In the USA generally present between June and October Two most common are St. Louis encephalitis and La Crosse encephalitis Japanese encephalitis most common outside the USA, transmitted during summer and autumn in temperate regions of China, Japan, Korea, and eastern areas of Russia Venezuelan equine encephalitis most common in Central and South America

VIRAL ENCEPHALITIS EPIDEMIOLOGY Enteroviruses Enteroviruses 70 and 71 Poliomyelitis Relatively acid- and heat-resistant resulting in fecal-oral transmission during the summer months Paralytic poliomyelitis: 13,000 cases reported to the WHO in 1991

CASE STUDY4 HPI A 38-year-old woman was admitted to the hospital in early August 2002 because of fever and confusion. She had been well until 4 days earlier when a headache gradually developed and increased in intensity, accompanied by mild photophobia and stiffness of the neck. Two days prior to admission she believed that she was mildly febrile. The day before the admission she was examined at another facility and told that she had a “viral illness”. She was given IV fluid s and discharged. On the morning of admission she awoke with shaking chills and a temp of 40C. During the day she was aware of a rapid heart beat, lightheadedness and lethargy. Her husband observed that she was confused and brought her to the hospital where she was admitted

CASE STUDY4 PMHx: Hodgkin’s disease at age 21, treated with radiation and chemotherapy, without splenectomy, remained healthy thereafter PSHx: none SHx: married, lives in Boston, 2 children, no tobacco, alcohol, nor drugs; two weeks prior to admission traveled to St. Louis area for eight days, took walks in a wooded area and visited the zoo; visited the north shore area of Massachusetts 5 days prior to admission, was bitten by mosquitos, returned home two days prior to admission because of symptoms

CASE STUDY4 ROS: no history of exposure to animals, no contact with ill persons, photophobia, visual problems, seizures, focal neurological deficits, dyspnea, cough, vomiting, diarrhea, arthralgia, or rash

CASE STUDY4 Vital signs at admission Physical Exam T 36.4, HR 100, RR 20, 90/60, Pox 99 on RA Physical Exam Slightly ill appearing, alert/oriented x3 but spoke in phrases of two to four words rather than complete sentences No rash, petechiae, or LAD Mouth and oropharynx normal Neck was rigid and Kernigs sign was present Lungs, heart, abdomen, and arms and legs were normal Neurological exam was normal

CASE STUDY4 Laboratory WBC 9,200, Hct 36.8, HgB 12.9, Plt 215,000 Diff: PNM 78%, Lymph 17%, Monos 5% Urine was normal CMP was normal Hcg negative PT/PTT normal

CASE STUDY4 Lumbar Puncture CT without contrast was normal Clear, no xanthochromia, RBC 139, WBC 107 Diff: Neutrophils 75, Lymph 22, Mono 3 Staining: abundant leukocytes, no AFB, GS negative VDRL negative, cryptococcal Ag negative, PCR for HSV 1 and 2 negative CT without contrast was normal

CASE STUDY4 Blood cultures were obtained. Vancomycin, Ceftriaxone, Doxycycline, and acyclovir were started.

CASE STUDY4 Hospital course Shortly after the patients arrival the temperature rose to 39.8C accompanied by frank rigors and somnolence Hospital day two the temp rose to 39.5C, when questioned she knew the name of the month but not the date or year or names of her children; later on the second day she became more lethargic and responded to questions only with “yes” An MRI of the brain was performed before and after contrast material, showed a subtle hyperintensity on the T2 images in both the hippocampalregions and slight meningeal enhancement

CASE STUDY4 Hospital course: On the third hospital day the temp max was 39.2; she was more responsive to commands than she had been on the previous day but could not distinguish the right hand from the left; she reported improvement in her headache and recognized her location; an EEG was done which revealed generalized low-amplitude slowing and continuous focal slowing over the entire left hemisphere; no epileptiform activity or organized electrographic seizure were seen

CASE STUDY4 Hospital course On the fourth day the temp max was 38.0C, there was tremor in her right arm but she was fully oriented and able to converse and provide details of her life; blood and CSF specimens were negative and vanc and ceftriaxone were stopped

CASE STUDY4 Hospital course On the fifth day the patient was alert and lucid; the tremor affected both arms, both legs, and the face with use but disappeared with rest; another LP was done On the sixth hospital day an MRI was repeated; the patient was fully oriented and conversed normally On the seventh day the patient was eating, walking, and no longer requested medication for headache; the action tremor persisted in the left arm and was improved in the right; the following day she was discharged home

CASE STUDY4 Second LP MRI Clear, no xanthochromia, RBC 300, WBC 32 Diff: PMN 4, lymph 94, monos 2 MRI Subtle high-intensity signal on fluid recovery images in the posterior parietal lobe along the cortical surface or in the pia, considered nonspecific in meningoencephalitis

Acute meningoencephalitis CASE STUDY4 Diagnosis Acute meningoencephalitis

DIFFERENTIAL DIAGNOSIS CASE STUDY4 DIFFERENTIAL DIAGNOSIS HSV Coxsackievirus St. Louis encephalitis Eastern equine encephalitis Tick-borne encephalitis West Nile encephalitis Lyme disease Leptospirosis HIV

CLINICAL PRESENTATION VIRAL ENCEPHALITIS CLINICAL PRESENTATION Clinical presentation and course can be markedly variable May be severely ill within 24 hours after initial signs and symptoms or may take several days before neurological involvement is seen Secondary encephalitis may not develop until seven to 30 days after the initial infectious process The general viral prodrome is several days long and consists of sudden fever, severe headache, nausea and vomiting, lethargy, and myalgias Specific prodrome in VZV, EBV, CMV, measles, and mumps include rash, lymphadenopathy, and parotid enlargement Dysuria and pyuria has been reported with SLE Extreme lethargy has been noted with WNE

CLINICAL PRESENTATION VIRAL ENCEPHALITIS CLINICAL PRESENTATION Classic presentation is encephalopathy with diffuse or focal neurologic symptoms: Behavioral and personality changes, decreased level of consciousness Stiff neck, photophobia, and lethargy Generalized or localized seizures (60% of children with LCE) Acute confusion or amnestic states Flaccid paralysis (10% with WNE) Less common symptoms include headache and other complaints of meningismus

CLINICAL PRESENTATION VIRAL ENCEPHALITIS CLINICAL PRESENTATION Neonatal HSV infection symptoms (1-45days) Skin, eye, and mouth lesions (early presentation) Encephalitis- change in level of alertness, irritability, seizures, poor feeding Evidence of widespread, disseminated disease, such as rash or shock

CLINICAL PRESENTATION VIRAL ENCEPHALITIS CLINICAL PRESENTATION Immunosuppression/HIV Toxoplasma encephalopathy accounts for as many as 40% of patients who are HIV positive with neurologic disease who present with a subacute headache, encephalopathy, and a focal neurologic complaint; this may be the presenting symptom of HIV infection

VIRAL ENCEPHALITIS PHYSICAL EXAM Signs may be diffuse or focal (80%of HSE patients present with focal findings Altered mental status and/or personality Hemiparesis, focal seizures, and autonomic dysfunction Movement disorders Ataxia Cranial nerve defects Dysphagia Meningismus Unilateral sensorimotor dysfunction

VIRAL ENCEPHALITIS PHYSICAL EXAM HSV infection in the neonate Herpetic skin lesions Keratoconjunctivitis Oropharyngeal involvement, particularly the buccal mucosa and tongue Seizures, irritability, change in level of attentiveness, bulging fontanels Shock, jaundice, hepatomegaly

ACUTE MENINGOENCEPHALITIS VIRAL ENCEPHALITIS DIAGNOSIS ACUTE MENINGOENCEPHALITIS Herpes simplex virus Varicella- -zoster Arboviruses

VIRAL ENCEPHALITIS ARBOVIRUSES Eastern Equine Localized to the Atlantic and Gulf coasts and Great Lakes areas The brain is markedly congested and there is widespread degenerative changes in the nerve cells; lesions are found in the gray and white matter and are most intensive in the cerebrum and brainstem Rare human infection Mainly affects infants, children, and adults over 50y; inapparent infection is common Sudden onset of drowsiness, stupor, or coma with convulsive seizures, HA, vomiting, neck stiffness, high fever, cranial nerve palsies, hemiplegia, focal neurologic deficits Mortality rate is 50% Duration varies from less than one day in fulminating cases to 4 weeks Sequelae are common: mental deficiency, cranial nerve palsies, hemiplegia, convulsions, aphasia Diagnosis is made by serology; CSF or blood

VIRAL ENCEPHALITIS ARBOVIRUSES St. Louis Two epidemiologic patterns: urban and rural Rural epidemics tend to occur in the western US Urban epidemics occur primarily in the Midwest, Mississippi river valley, and eastern US; outbreaks can be abrupt and extensive because humans are the intermediate host Primarily affects the elderly; midsummer to early fall Nuclear masses of the thalamus and midbrain are more affected than is the cortex Usually results in inapparent infection 75% of patients with clinical manisfestations have encephalitis Hyponatremia secondary to SIADH occurs in 25% Acute course results in death or recovery in 2-3 weeks; mortality is 2-20% Most common sequelae: headaches, insomnia, easy fatigability; 25% have permanent neurologic sequelae Diagnosis is made by IgM assay

VIRAL ENCEPHALITIS ARBOVIRUSES Japanese encephalitis Occurrence can be endemic (tropical) or epidemic (temperate) Major medical problem throughout Asia; 20,000 cases annually Involves the entire cerebral cortex, basal ganglia, cerebellum, and spinal cord Disease is most common in children Mortality rate of 60% Severe neurologic residuals and mental defects are common An inactivated vaccine is used routinely in Japan, China, Korea, and is available for travelers to the regions Diagnosis is made by isolation of the virus in CSF, blood, or cerebral tissue and/or by serology IgM

VIRAL ENCEPHALITIS ARBOVIRUSES La Crosse The most prevalent arboviral infection in children in North America Often goes unrecognized Typically cannot be isolated from CSF Can masquerade as enteroviral meningitis when mild and as HSV encephalitis when severe Occurs most frequently in midwestern states and along the eastern seaboard Headache, N/V, changes in sensorium, meningeal irritation, and upper motor neuron signs WBC is usually elevated Mimics partially treated bacterial infections, WBC, CRP elevated Sequelae include cognitive impairment and neurobehavioral effects (ADHD) Diagnosis is made by serum IgG and/or IgM antibodies

VIRAL ENCEPHALITIS ARBOVIRUSES West Nile Enzootic in Africa, Asia, and Europe First outbreak recognized in Western Hemisphere in New York City in August 1999 Reservoirs include a variety of wild and domestic birds Vectors are mosquitos; Culex Most infections in humans are subclinical; overt disease occurs in approximately 1 out of 100 infections Incubation period ranges from 3 to 15 days Presents with fever, weakness, N/V, AMS, Infections in older adults and immunocompromised patients are characterized by severe neurological disease; acute flacid paralysis, anterior horn involvement In the NYC outbreak, a relation between WNE and DM showed increased fatal outcome Diagnosis is made by IgM and IgG antibody-capture enzyme immunoassays and for confirmation, plaque-reduction neutralization assays in cell culture; test both serum and CSF

VIRAL ENCEPHALITIS ARBOVIRUSES West Nile In 2002 there were more than 3500 cases and more than 200 deaths in the USA It can be estimated that hundreds of thousands of Americans were infected during 2002 In 2002 WNV transmission occurred by blood transfusions, organ donations, and breast feeding No effective therapies Prevention is by reduced exposure to vectors, personal protection measures Vaccine under development

DIFFERENTIAL DIAGNOSES VIRAL ENCEPHALITIS DIFFERENTIAL DIAGNOSES Brain abscess Leptospirosis Subarachnoid hemorrhage Systemic lupus erythematosus Lyme disease Rocky mountain spotted fever Toxoplasmosis Tuberculosis CNS syphilis CVA Acute confusional states secondary to drugs, toxins, alcohol withdrawl, psychosis Head trauma Tumor Amoeba (Naegleria, Acanthamoeba)

VIRAL ENCEPHALITIS DIAGNOSTIC WORKUP Laboratory Imaging Electroencephalography Procedures

VIRAL ENCEPHALITIS LABORATORY Complete blood count with differential (usually within normal range) Serum electrolytes (usually normal) Liver function testing PT/PTT Urine/serum tox screen Viral serology HSV cultures of lesions, blood, CSF CSF PCR for HSV Heterophile antibody and cold agglutinins for EBV Serologic tests for toxoplasmosis

VIRAL ENCEPHALITIS IMAGING A head CT with and without contrast should be performed in virtually all patients prior to an LP to search for evidence of elevated ICP, obstructive hydrocephalus, or mass effect. An MRI is more likely to show abnormalities earlier in the disease course than the head CT. An MRI may show several foci of increased T2 signal in the medial temporal lobes and inferior gray matter in HSE. A head Ct may show petechial hemorrhage in the same areas. EEE and tick-borne encephalitis may show increased signals in the basal ganglia and thalami. In Toxoplasmosis, a CT with contrast typically reveals several nodular or ring-enhancing lesions.

ELECTROENCEPHALOGRAHPY VIRAL ENCEPHALITIS ELECTROENCEPHALOGRAHPY HSV- Characteristic paroxysmal lateral epileptiform discharges (PLEDS) are often observed Diffuse slowing of background rhythms is the most common EEG abnormality Nonspecific and is present in patients with diffuse encephalopathies of various causes including toxic, metabolic, anoxic, and degenerative Focal slowing suggests localized parenchymal dysfunction Virtually diagnostic EEG changes are seen in subacute sclerosing panencephalitis Stereotyped bursts of high-voltage Delta waves recurring at regular 4- to 10-second intervals

VIRAL ENCEPHALITIS LUMBAR PUNCTURE CSF PCR: A PCR for DNA HSV is 100% specific and 75-98% sensitive within the first 24-45 hours. Types 1 and 2 cross-react, but there is no cross-reactivity with other herpes viruses.

VIRAL ENCEPHALITIS BRAIN BIOPSY Criterion standard because of its 96% sensitivity and 100% specificity

VIRAL ENCEPHALITIS TREATMENT General measures Treat for shock or hypotension with crystalloid Consider airway protection in patients with altered mental status Consider seizure precautions In suspected HSV, acyclovir should be initiated as soon as possible Signs of hydrocephalus and ICP General measures: manage fever and pain, control straining and coughing and avoid seizures and systemic hypotension Early use of diuresis, steroids, hyperventilation

VIRAL ENCEPHALITIS TREATMENT Empiric emergency treatment for HSV meningoencephalitis and VZV encephalitis is acyclovir 10mg/kg q8h for 14-21 days; give acyclovir 10-15mg/kg IV q8h for neonatal HSV; in pediatrics give acyclovir 10mg/kg IV q8h In HIV-positive patients, consider foscarnet, given increased incidence of acyclovir-resistant HSV and VZV

VIRAL ENCEPHALITIS PREVENTION Personal preventive measures Avoid areas Insect repellent: DEET Proper clothing Mosquito eradication Vaccination: JE

VIRAL ENCEPHALITIS REFERENCES Merritt’s Textbook of Neurology, Ninth Edition 1995 Pathology, Rubin and Farber; Second Edition 1994 Encephalitis, Lazoff, et al.; emedicine September 9, 2002 Encephalitis, Japanese; CDC Website Travelers Health Hirsch M, Werner B. Case 17-2003: A 38-year-old Woman with Fever, Headache, and Confusion; Case Records of the Massachusetts General Hospital. N ENG J MED 2003;348:2239-2247 Nash D, Mostashari F, Fine A, et al. The Outbreak of West Nile Virus Infection in the New York City Area in 1999,. N ENG J MED 2001;344:1807-1814 McJunkin J, De Los Reyes E, Irazuzta J, et al. La Crosse Encephalitis in Children. N ENG J MED 2001;344:801-807