We present a 24-year-old man with a 2-year history of progressive right-sided monocular vision loss with no other symptoms. An MRI showed a meningioma compressing the right optic nerve and the cavernous sinus. The tumour was partially resected. Eight days after discharge the patient was admitted with fever, a severe stabbing headache, insomnia, nausea and vomiting. A FilmArray panel and a cerebral biopsy were performed which were positive for herpes simplex virus 1 (HSV-1). An MRI of the brain showed asymmetric bilateral lesions in the frontobasal region with predominance of the right side. Acyclovir was started and continued until completing 21 days. A month after discharge, he started experiencing insomnia, trichotillomania, limb tremor, persistence of abulia, apathy and emotional lability. An HSV-1 encephalitis relapse was suspected, acyclovir and foscarnet were started. Due to the poor response to antiviral therapy CSF was tested, which was positive for anti-NMDA receptor encephalitis. A treatment course of intravenous immunoglobulin was started with a favourable outcome.
