Incidence and pathogenesis of clinical relapse after herpes simplex encephalitis in adults.

• OBJECTIVES: To study the occurrence of relapse of herpes simplex encephalitis (HSE) and to find out whether soluble activity markers in cerebrospinal fluid (CSF) indicate direct viral or immune- mediated events. METHODS: A consecutive series of 32 adult survivors of HSE were followed to determine the incidence of clinical relapse of HSE. Four patients had neurological deterioration interpreted as relapsing HSE. Four non-relapsing HSE cases were selected as matched controls. Fifty nine batched, paired CSF and serum samples from the eight HSE patients were analysed for soluble activity markers, predominantly cytokines and mediators (interferon-gamma, soluble CD8, tumour necrosis factor-alpha, and interleukin-10), amount of HSV-DNA and markers of glial and neuronal destruction (neurofilament protein, glial fibrillary acidic protein, S-100-beta, and neuron specific enolase). RESULTS: Relapse of HSE was diagnosed in 3 of 26 (12 %) acyclovir-treated patients (5 episodes during 6.1 years of followup) and in 1 of 6 vidarabine-recipients. All relapses occurred from 1 to 4 months after acute HSE, except for a second relapse after 3.3 years in one patient. Computer tomography at relapses revealed few abnormalities apart from those found during the primary disease. Intravenous acyclovir and corticosteroids were given for 7-21 days in all the relapse patients. All relapse patients seemed to recover to the pre-relapse condition. HSV-DNA was demonstrated in CSF in all patients during the acute stage but not in any of 13 CSF samples taken during relapse phases. The HSV viral load during the acute stage of HSE was not higher or of longer duration in the relapsing patients than in the non-relapsing HSE controls. The levels of sCD8 were increased in nearly all CSF samples tested with peaks of sCD8 at one month of acute HSE. In all episodes of relapse, sCD8 peaks were detected during the first week at high levels. CSF levels of neuron-specific enolase, S-100 and glial fibrillary acidic protein were markedly lower at relapse than at the acute stage of HSV-1 encephalitis. CONCLUSION: The lack of demonstrable HSV DNA in CSF, the lack of acute CSF signs and the lack of signs of neural and glia cells destruction indicate that a direct viral cytotoxicity is not the major pathogenic mechanism in relapse. Instead, the pronounced CSF proinflammatory immunological response and the relative lack of CSF anti-inflammatory cytokine IL-10 response suggest immunologically-mediated pathogenicity.

Nyckelord

Adolescent

Adult

Aged

Aged

80 and over

Case-Control Studies

Cytokines

cerebrospinal fluid

Encephalitis

Herpes Simplex

cerebrospinal fluid

epidemiology

pathology

physiopathology

Enzyme-Linked Immunosorbent Assay

methods

Female

Follow-Up Studies

Glial Fibrillary Acidic Protein

cerebrospinal fluid

Herpes Simplex

cerebrospinal fluid

genetics

Humans

Incidence

Male

Middle Aged

Phosphopyruvate Hydratase

cerebrospinal fluid

Prospective Studies

RNA

Messenger

biosynthesis

Recurrence

Retrospective Studies

Reverse Transcriptase Polymerase Chain Reaction

methods

Time Factors

Publikations- och innehållstyp

ref (ämneskategori)

art (ämneskategori)