Neurosyphilis Concurrently Presenting With Limbic Encephalitis and Normal Pressure Hydrocephalus: A Case Report

Neurosyphilis may present with a variety of clinical symptoms and neuroimaging findings and is thus likely to be overlooked. We report a case of neurosyphilis presenting with dementia, limbic encephalitis, and normal pressure hydrocephalus.

A 47-year-old man had gradually experienced cognitive decline for over a year. He was admitted to a psychiatric hospital. Brain computed tomography imaging showed ventricular enlargement. Serological tests for syphilis were positive. He was transferred to our hospital, where he exhibited gait disturbance, cognitive impairment, and urinary incontinence. Brain magnetic resonance imaging showed high signal intensity in both medial temporal lobes. Treponemal cerebrospinal fluid testing was positive. He was treated with intravenous benzylpenicillin for 36 days and two courses of intravenous methylprednisolone pulse therapy. His psychomotor agitation required physical restraint for 37 days and treatment with risperidone. Although his gait disturbance and urinary incontinence improved, no clinically meaningful change in cognitive impairment was observed. The high signal intensity on repeat imaging was attenuated. He was transferred back to the psychiatric hospital 3 months after admission.

This case of neurosyphilis was characterized by early-onset dementia with limbic encephalitis and normal pressure hydrocephalus. Psychiatrists should be aware of the possibility of neurosyphilis in such cases.