Neurology: Case of the Month

Test Yourself — Patient 51

Herpes Simplex Encephalitis (HSV Type 1)

1. Herpes simplex virus (HSV) encephalitis can be reliably excluded by:
   • [ A ] Failure to respond clinically to acyclovir
   • [ B ] Apparently mild clinical disease
   • [ C ] Normal or near-normal CSF studies
   • [ D ] Absence of focal findings on EEG or MRI
   • [ E ] Negative PCR assay for HSV DNA
   • [ F ] None of the above
2. Which of the following presentations is MOST likely to result from herpes simplex infection of the brain?
   • [ A ] A 25 year old woman with five days of fever, night sweats, fluctuating level of consciousness, and a heart murmur.
   • [ B ] An 18 year old man with low-grade fever, headache, neck stiffness, and mild lethargy following a week of snorkeling in freshwater lakes in Florida.
   • [ C ] A 40 year old man with fever and somnolence developing after hospital admission for acute, new-onset psychosis, found to have periodic epileptiform discharges emanating from the right temporal region.
   • [ D ] A 31 year old woman with two weeks of fatigue and arthralgias, presenting with progressively worsening headache, mild fever, and a facial rash.
3. Diagnosis of HSV encephalitis may be confirmed by all of the following assays, EXCEPT:
   • [ A ] Culture of HSV from CSF or brain tissue
   • [ B ] CSF PCR amplification and Southern blotting to detect HSV DNA
   • [ C ] Active herpes labialis associated with clinical encephalopathy
   • [ D ] Brain biopsy with demonstration of HSV RNA and antigens in brain tissue
   • [ E ] All of the above would confirm a diagnosis of HSV encephalitis
4. Lack of clinical response to acyclovir treatment in suspected herpes simplex encephalitis may result from all of the following, EXCEPT:
   • [ A ] Arboviral infection
   • [ B ] Unrecognized status epilepticus
   • [ C ] Delayed initiation of treatment
   • [ D ] Inadequate suppression of HSV replication
   • [ E ] Any of the above could account for apparent treatment failure
5. Which of the following statements are TRUE?
   • [ A ] Resistance to acyclovir may result from mutations in the herpes simplex viral reverse transcriptase.
   • [ B ] Additive effects of combined treatment with foscarnet and acyclovir on HSV replication have been demonstrated in animal models in vivo.
   • [ C ] Resistance of herpes simplex virus to acyclovir cannot occur in the absence of a documented mutation in the viral DNA polymerase.
   • [ D ] Nephrotoxicity of acyclovir may result from renal tubular precipitation during rapid infusion or excessive dosage.

 

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