1. ENCEPHALITIS

2. Selected Viral causes of acute encephalitis/myelitis Herpesvirus: Herpes simplex virus, Varicella–zoster virus, Herpes B virus, Epstein–Barr virus, Cytomegalovirus Flaviviridae: West Nile, Japanese, Dengue Poliovirus Rabies Meales, mumps Influenza (postinfectious?) HIV

3. Selected non-Viral causes of acute encephalitis/myelitis Rickettsia, Brucella, Mycoplasma, Bartonella, Lyme dis., syphilis Toxoplasma, Plasmodium falciparum Endocarditis Vasculitis Carcinoma Drug reaction (chemotherapy: methotrexate)

4. Herpes simplex Encephalitis The most commonly identified cause of acute, sporadic viral encephalitis; 10 to 20% of all cases Subtype 1 virus causes more than 95% of cases of HSV encephalitis In children and young adults, primary HSV infection may result in encephalitis; virus enters the central nervous system (CNS) by neurotropic spread from the periphery via the olfactory bulb

5. Herpes simplex Encephalitis In about 25% of the patients, the HSV-1 strains from the oropharynx and brain tissue of the same patient differ; thus some cases may result from reinfection with another strain of HSV-1 that reaches the CNS Most adults with HSV encephalitis have clinical or serologic evidence of mucocutaneous HSV-1 infection before the onset of the CNS symptoms. HSV DNA has been demonstrated in brain tissue from healthy adults. ( = reactivation)

6. Herpes simplex Encephalitis בת 51, בריאה בדר " כ, מזה 3 ימים חום 37.8 וכאב ראש שהלכו והתגברו. היום הובאה לחדר המיון עקב מאורע של התכווצויות. כשהתעוררה הייתה מבולבלת ולא התמצאה במקום ובזמן. בבדיקה נמדד חום 39.6, נצפתה דיספזיה ( קושי בדיבור ) וחולשה בפלד הגוף הימני.

8. Herpes simplex Encephalitis: Diagnosis CSF WBC: 20-300 cells/mm 3 (rare;y < 5) Protein: 30-2,500, median 80 (normal<60) Glucose usually normal EEG: spike and slow wave activity from the temporal lobe. Sensitivity 85%. Specificity 33%.

9. Herpes simplex Encephalitis (HSE): Diagnosis CT: Edema in the temporal lobe hemorrhagic necrosis midline shift Low density lesions of the temporal lobe: 44/50 (88%) in HSE and in 8/71 (11%) in non-HSE. 16/44 (36%) HSE patients had lesions in the frontal lobe. 1/44 occipital, 1/44 parietal. First 5 days: CT sensitivity 73%, specificity 89% >5 days: CT sensitivity 90%, specificity 92%

10. HSE: MRI is more sensitive, especially for identifying edema. The neuroimaging technique of choice!!!

11. Herpes simplex Encephalitis: confirmation of etiology Brain biopsy (complications 3%) Serologic analysis in serum and CSF: low sensitivity in the first 10 days. CSF Cultures: negative PCR in CSF: highly sensitive and specific. The diagnostic procedure of choice.

12. Detection of intrathecal anti-HSV antibodies

13. PCR of HSV DNA from CSF samples

14. HSE: acute, focal, necrotizing encephalitis with cerebral edema and petechial hemorrhages

15. Herpes simplex Encephalitis : Treatment IV acyclovir (10 mg/kg x 3/day over 1 hour) is effective in reducing the rates of death (70% 24%) and morbidity Early therapy is a critical factor in outcome!!! In suspected cases: start acyclovir empirically If PCR negative and no other support for HSE, stop acyclovir Long-term cognitive abnormalities