Twice Negative PCR in a Patient With Herpes Simplex Virus Type 1 (HSV-1) Encephalitis
Bibliographic record
Abstract
Untreated herpes simplex virus type 1 (HSV-1) encephalitis is associated with high mortality. Missed cases can have devastating consequences. Detection of HSV-1 in cerebrospinal fluid (CSF) with polymerase chain reaction (PCR) is reported to have high sensitivity and specificity and is considered the diagnostic gold standard for HSV-1 encephalitis. In this article, we report a case of autopsy-confirmed HSV-1 encephalitis where CSF PCR returned negative on 2 occasions. A 64-year-old man presented with fever, left-sided weakness, and altered level of consciousness. Magnetic resonance imaging demonstrated right mesial temporal lobe diffusion restriction and electroencephalography showed right lateralized periodic discharges. Lumbar puncture was performed on day 1 for which CSF PCR returned negative for HSV-1. Empiric antiviral and antibiotic treatments were continued due to high clinical suspicion of HSV-1 encephalitis. Repeat lumbar puncture on day 5 was unchanged and empiric treatments were discontinued. On day 13, he developed status epilepticus requiring intensive care unit admission. A third CSF sample returned positive for HSV-1. Acyclovir was restarted but he continued to clinically worsen and supportive care was withdrawn. Autopsy confirmed widespread HSV-1 meningoencephalitis. Negative CSF PCR should be interpreted with caution in cases where there is high clinical suspicion of HSV-1 encephalitis. Current guidelines suggest repeating CSF HSV-1 PCR within 3 to 7 days in suspicious cases while continuing empiric therapy. However, missed cases can occur even with repeated testing. Empiric treatment with acyclovir should be considered in cases with high clinical suspicion of HSV-1 encephalitis, while investigations for alternate treatable diagnoses are continued.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.004 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.003 | 0.003 |
| Insufficient payload (model declined to judge) | 0.001 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".