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Herpes simplex virus type 1 encephalitis in acquired immunodeficiency syndrome
F Chrétien1, L Bélec, D A Hilton
1Laboratoire d'Anatomie Pathologique (Neuropathologie), Hôpital Raymond Poincaré-Faculté de Médecine Paris-Ouest, Garches, France.
Neuropathology and Applied Neurobiology
|October 1, 1996
Summary
Herpes simplex virus (HSV) encephalitis in advanced AIDS patients is rare and atypical, often lacking typical inflammation. Advanced diagnostics like PCR are crucial for identifying HSV type 1 as the cause.
Area of Science:
- Neurology
- Virology
- Pathology
Background:
- Herpes simplex virus (HSV) infections of the central nervous system (CNS) are infrequent and present atypically in patients with acquired immunodeficiency syndrome (AIDS).
- This review focuses on a unique case of diffuse encephalopathy in an AIDS patient, highlighting unusual neuropathological findings.
Observation:
- Neuropathological examination revealed extensive necrotic and hemorrhagic changes in the temporal lobes, insulae, and cingulate gyri, with abundant Cowdry type A intranuclear inclusions but minimal inflammation.
- Electron microscopy confirmed herpes virions, while immunocytochemistry showed positivity for both HSV type 1 and 2. However, in situ hybridization and PCR confirmed HSV type 1 exclusively, excluding HSV type 2.
- Cytomegalovirus (CMV) ventriculitis was present but distinct from the HSV encephalitis. No evidence of HIV encephalitis was found, with HIV undetectable by immunocytochemistry or PCR.
Findings:
- The case presented with numerous apoptotic neurons and a significant macrophage reaction, suggesting a severe neuronal injury.
- Distinguishing between HSV type 1 and 2 can be challenging with standard immunocytochemistry, necessitating advanced techniques like in situ hybridization or PCR.
- In AIDS patients, HSV-1 is typically implicated in encephalitis, whereas HSV-2 is more commonly associated with myelitis.
Implications:
- The rarity of reported cases suggests a diminished immune response in advanced AIDS, hindering the typical necrotizing encephalitis development.
- Accurate differentiation of HSV types is critical for understanding pathogenesis and guiding treatment in immunocompromised individuals.
- Cytomegalovirus encephalitis frequently co-occurs with HSV encephalitis in AIDS patients, emphasizing the need for comprehensive diagnostic approaches.