Neurosyphilis presenting as limbic encephalitis.

Area of Science:

• Neurology
• Infectious Diseases

Background:

• Limbic encephalitis is an inflammatory condition affecting the brain's temporal lobes, often presenting with seizures.
• Corticosteroid therapy is a common initial treatment for suspected limbic encephalitis.

Observation:

• A man in his 50s experienced persistent focal seizures, inflammatory cerebrospinal fluid (CSF), and mesiotemporal lobe hyperintensities on MRI despite corticosteroid treatment.
• The patient later developed neuropsychiatric symptoms, leading to the diagnosis of neurosyphilis.

Findings:

• Neurosyphilis, a complex bacterial infection, can manifest with neurological and psychiatric symptoms, including a limbic encephalitis-like presentation.
• Cerebrospinal fluid (CSF) pleocytosis and temporal lobe MRI hyperintensities are noted in neurosyphilis cases mimicking limbic encephalitis.

Implications:

• Persistent neurological or CSF abnormalities despite immunosuppressive therapy for limbic encephalitis necessitate exploring alternative diagnoses.
• Neurosyphilis should be considered in the differential diagnosis of chronic meningoencephalitis, especially when initial treatments are ineffective.