Introduction: A 24 year-old healthy male amateur rugby player presented with headache and left sided facial weakness; without recent travel, illicit drug use, nor unprotected sexual contact. MRI confirmed a right middle cerebral artery (MCA) infarction. ‘Young stroke’ work-up was normal. Initially recovering well, he re-presented to his local hospital a few weeks later with headache and hypersomnolence, without focal deficits. MRI suggested interval subacute infarction, alongside thalamic high signal.

Methods: He was transferred to the regional neurosciences centre and anticoagulated for a suspected cardioembolic source, disproven by transoesophageal echocardiogram, prolonged ECG monitoring and blood cultures. Repeat MRI appearances raised the possibility of right MCA focal vasculopathy, with subtle temporal lobe mass effect. In view of intermittent pyrexia, encephalitis was suspected and Acyclovir commenced.

Results: Lumbar puncture (LP) revealed WBC of 359 (lymphocytic), RBC 10, protein 1.16 and glucose 2.9 (serum 5.2). HSV-1 PCR positive. Lyme, hepatitis, HIV and syphilis, autoimmune and connective tissue screening were all negative. Repeat CSF HSV-1 PCR at 14, 21 and 28 days remained positive despite ongoing treatment. He was discharged with a further 2 months of oral Valacyclovir prior to interval LP and MRI.

Conclusion: Review of the original imaging supports the diagnosis of acute infarction. Occam’s razor would dispute dual diagnosis of cryptogenic stroke then HSV-1 encephalitis. There is scant evidence in the literature for HSV-1 vasculopathy, by contrast with VZV associated vasculopathy, but we found no evidence of VZV in this case. Therefore this appears an unusual presentation of HSV-1 infection, culminating in vasculopathy, stroke and encephalitis.