HSV Encephalitis: Non-classical PCR Results with a Classical Clinical Presentation in a 5-year Old Girl
Ruth Seleznick1, Victoria Mazo1, Alianis Tirado1, Elizabeth Fletcher2, Saba Ahmad1
1Child Neurology, 2Pediatrics, Johns Hopkins All Children's Hospital
Background:
Herpes Simplex Encephalitis (HSE) is a leading cause of fatal sporadic encephalitis in the Western world for those older than 6 months. CSF PCR detection of HSV is the preferred diagnostic method for HSE, showing >95% sensitivity and specificity when compared to brain biopsy cultures. However, PCR sensitivity in neonates and infants is more variable, ranging from 75% to 100%. Moreover, one of the most prominent studies showed initial PCR detected HSV-1 DNA in 79% of children with HSE, but ultimately all but one child had at least one positive PCR test in that study. We present a case of HSE with persistently negative CSF PCR results.
Results:
5-year-old girl with history of autism presented with body stiffening and left-sided jerking concerning for seizure. She was treated with lorazepam and levetiracetam successfully. Continuous EEG revealed right temporal slowing. She developed a fever shortly after admission, which prompted initiation of empiric antibiotics and acyclovir. Brain MRI revealed right temporal lobe extensive FLAIR hyperintense signal abnormality with associated restricted diffusion, hemorrhage, leptomeningeal and pachymeningeal enhancement (Pic 1). Initial CSF showed elevated protein, 1955 RBCs and 5 WBCs, but negative HSV PCR. Acyclovir was continued, and repeat lumbar puncture 3 days later showed improved RBCs (323) but persistently negative HSV PCR. Serum HSV IgG and IgM were positive.
Following clinical improvement, patient was discharged on a 21-day acyclovir course. Follow-up MRI at 2 months showed signal improvement with residual gliosis, cortical laminar necrosis, and minimal residual meningeal enhancement (Pic 2).
Conclusions:
This case emphasizes the need to maintain a high index of suspicion for HSV etiology in patients with clinicoradiological findings of viral encephalitis, even when PCR is repeatedly negative. The unusual nature of persistent negative PCR in an immunocompetent 5-year-old highlights the value of reporting such cases.
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