What’s smelling?

69 yo M with PMH of HTN, GERD presented with malaise, decreased appetite and PO intake, generalized weakness, HA, subjective fevers/chills and hyperosmia for the preceding 3-4 days.

On admission, was found to be volume deplete and with the working diagnosis of a ?viral syndrome was admitted for further work up. On HD#2, he develops acute mental status changes and becomes confused, AOx1, fidgety with behavioral changes of constantly folding linen and being pre-occupied with it.

CSF showed lympocyte predominance with no RBCs. CT was initially negative for any acute changes but subsequently an MRI was obtained which revealed hyperintensity on T2 weighted images in the medial bitemporal cortices R>L suggstive of HSV encephalitis. CSF PCR later that day returned positive for HSV (speciation pending). Paitent is currently receiving IV acyclovir for treatment.

The hyperosmia is likely due to temporal lobe involvement and the behavioral change likely due to limbic system involvement.

Take home points:

– In a patient with fever and mental status change, if encephalitis +/-meningitis is suspected and there is an anticipated delay in performance of LP, then it is recommended that first dose of empiric antibiotics be delivered

– The above is especially true if HSV encephalitis is suspected as untreated HSV CNS infection has very high mortality rate of 70% and tremendous morbidity with residual neurological deficits

– HSV PCR is the new “gold standard” test which in the appropriate clinical setting has a very high sensitivity and specificity

Guidelines for viral encephalitis with review of literature and pathogenesis.