Abstracts

Rationale:
HSV encephalitis is an uncommon neurological disorder, with classic presentation including confusion or behavioral changes, viral prodrome of fever headache and vomiting, and elevated HSV antibodies. Patients can also present with seizures or focal weakness, with variable imaging findings and clinical course. However, atypical presentation along with atypical imaging suggestive of alternate etiology such as ischemia, is very rare.
Method:
A 63 year old male presented with fevers, chills, polydipsia, hiccups, and new onset generalized tonic clonic seizure. Exam was suggestive of postictal state with left facial droop, left dense hemiplegia, right gaze, and extinction. However CT head showed focal hypodensities in the right subinsular/temporal lobe consistent with possible early ischemic changes. Due to focal deficit and with CT support, acute stroke was suspected. Patient was given IV tPA and MRI brain showed DWI diffusion restriction in the right insular, inferior frontal, and temporal lobes. There was surrounding edema with ADC hypointensity in part of the same regions. There was subsequent small acute parenchymal hemorrhage in the right subinsular region, not related to tPA and not likely to cause profound mental status change. His weakness improved, however it did not resolve and he continued to spike fevers with progressively worsening lethargy. Due to the lethargy an EEG was done, which showed lateralized periodic discharges (LPDs) and electrographic seizures over the right hemisphere, evolving into nonconvulsive status epilepticus. Despite 3 antiepileptics and improved EEG the patient remained lethargic. Given the status epilepticus with right temporal LPDs and focal deficit, herpes encephalitis was considered and lumbar puncture was performed. Follow up MRI showed spread of diffusion restriction to the left insula and left medial frontal lobe.
Results:
Lumbar puncture showed elevated WBC, lymphocytosis, and positive HSV PCR. Patient had HSV IgM positive in serum, which helped to confirm herpes simplex infection. Patient improved after treatment with high-dose acyclovir for herpes encephalitis.
Conclusion:
Herpes encephalitis can present as acute onset focal status epilepticus with MRI that can mimic acute stroke. This patient presented with generalized tonic clonic seizure and imaging suggestive of acute stroke; EEG showed nonconvulsive status epilepticus and patient had focal deficit with worsening lethargy, so lumbar puncture was done to rule out HSV infection. Lumbar puncture should be considered in all patients with new onset focal status epilepticus, focality on exam, fevers and progressive mental status change. A closer look and repeat MRI should be considered in all patients with clinical deficit resembling a stroke with progressive lethargy, to rule out findings suggestive of a viral encephalitis. In such patients without improvement of mental status despite treatment, herpes encephalitis should be highly suspected.
Funding:
:No funding.