European encephalitis guideline: aciclovir on suspicion, and do not replace specific CSF PCR with a panel

Design

Joint EAN/ESCMID clinical practice guideline, GRADE methodology

Population

Adults with suspected infectious encephalitis

Primary outcome

Recommendations on diagnosis and management across 16 clinical questions

Effect

2 GRADE recommendations (early IV aciclovir; against replacing specific PCR with multiplex panels); 13 good practice statements

The European Academy of Neurology and ESCMID have jointly updated adult infectious encephalitis guidance for the first time since 2010. The panel considered 16 clinical questions using GRADE.

Only two reached formal recommendations. First, start intravenous aciclovir as soon as encephalitis is suspected, without waiting for test results. Second, do not use multiplex cerebrospinal fluid PCR panels in place of pathogen-specific PCR when diagnosing suspected infectious encephalitis in adults. On corticosteroids in proven herpes simplex encephalitis, the panel could not recommend either way. Thirteen good practice statements cover when to suspect encephalitis, microbiological and other investigations, treatment and rehabilitation.

The second recommendation matters most on the ward, because multiplex panels are fast and increasingly the default request. A concern often raised about panels is lower sensitivity for some targets, so a negative panel can falsely reassure. The guideline authors note how thin the evidence base is overall; these two points are where it was strong enough to commit.

• Start intravenous aciclovir as soon as encephalitis is suspected; do not wait for lumbar puncture or PCR.
• Request pathogen-specific CSF PCR, including HSV and VZV, even when a multiplex panel is also sent.
• Do not stop aciclovir on a negative multiplex panel alone.
• There is no recommendation for or against corticosteroids in proven HSV encephalitis; follow local specialist advice.
• In India, consider local causes such as Japanese encephalitis, scrub typhus and dengue alongside HSV when planning tests.

Why it matters

Multiplex panels are becoming the default CSF test, and this guideline says they should not replace specific PCR.

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