Neurosyphilis presenting as acute ischemic stroke.

Neurosyphilis is a broad term used to describe an infection caused by Treponema pallidum in the central nervous system. While this was a common cause of stroke in the 19th century, it saw a decline after the introduction of penicillin. However, in the recent past, there has been an increase in the incidence of syphilis, especially with HIV coinfection. Neurosyphilis results from an untreated primary syphilis. Neuropsychiatric disorder appears to be the commonest manifestation followed cerebrovascular accident, myelopathy, ocular disease and seizure. Known as the 'great imitator', this entity, however, may be easily missed if not for a high index of suspicion. This is especially so because of its similar presentation to other more common clinical conditions. We describe the case of a 39-year-old man displaying acute global aphasia and right-sided facial weakness in keeping with a left middle cerebral artery infarct. This was confirmed with computed tomography of the brain, and subsequently, further investigations revealed a diagnosis of neurosyphilis. The patient was treated with intravenous benzylpenicillin and recovered well with treatment. © Royal College of Physicians 2020. All rights reserved.