Neurosyphilis: The Great Imitator

Abstract

Syphilis is a sexually transmitted disease caused by spirochete Treponema pallidum, with a growing incidence documented in recent years. Its clinical course is divided into three phases - primary, secondary, and tertiary syphilis - and virtually any organ can be affected, resulting in diverse clinical manifestations, making the diagnosis challenging. Neurosyphilis is a progressive, destructive disease of the central nervous system (CNS) that can develop at any stage of the infection, leading to meningeal involvement, meningovascular disease, or parenchymal syphilis (including tabes dorsalis and general paresis). Its clinical manifestations are heterogeneous and vary from focal neurologic signs to neuropsychiatric manifestations. The diagnosis is based mainly on the clinical picture and study of cerebrospinal fluid. Neuroimaging is helpful and sometimes essential, with magnetic resonance imaging being the most sensitive radiologic method, although there are no pathognomonic radiologic signs. Treatment of all forms of neurosyphilis is based on parenteral penicillin. We present a case of neurosyphilis in a patient presenting with a subacute confusional state and initial imaging findings suggestive of metastatic CNS lesions.

Keywords: acute confusional state; autoimmune limbic encephalitis; cns lesions; neurosyphilis; paraneoplastic encephalitis syndromes.

Figure 1. Cranial CT scan at admission, showing hypodense lesions in the anterior regions of both temporal lobes and a meningioma of the right parietal lobe.

CT - computerized tomography

Figure 2. Cranial MRI scan (axial plane) showing hyperintense signal of subcortical white matter - bitemporal regions, mesial temporal lobe, corpus callosum, and internal capsule. Meningioma of the right parietal lobe.

MRI - magnetic resonance imaging