To report a clinical case on neurosyphilis.

Clinical history, neuroimaging and lab investigations, and neuropsychological assessments.

A 66-year-old married man was admitted to an Old Age psychiatric ward presenting with a two-year history of desinhibited behaviour, hetero-aggression and a gradual loss of his ability cope with activities of daily living. His Mini Mental State Examination (MMSE) score was 20/30 on admission. The symptoms described above raised the working diagnosis of a frontotemporal dementia. Computerized axial tomography was normal. Laboratory and additional examinations were performed. Serological tests for syphilis were positive for both the Venereal Disease Research Laboratory test (VDRL) and Treponema pallidum hemaglutination test (TPHA). Cerebrospinal fluid (CSF) revealed a positive VDRL (cytology: 2 erythrocytes/μl, 30 leucocytes/μl with 24 mononuclear cells/ μl). Additional tests including human immunodeficiency virus (HIV) test were negative. Based on these findings the patient was treated for neurosyphilis according to the IUSTI 2008 European Guidelines on the management of Syphilis: Benzyl penicillin 18 million units i.v. daily, as 3 million units every four hours during 21 days. Two months later, he scored 28/30 at the MMSE but showing only slight improvement at the executive function battery.

Neurosyphilis remains a differential diagnosis for a wide variety of psychiatric syndromes, including dementia. However, the incidence of neurosyphilis presenting initially with frontotemporal impairment is unclear. High-risk groups such as patients with neuropsychiatric diseases should be routinely screened with serological tests in order to prevent morbidity and help to eliminate syphilis.