Deciphering the Great Imitator: Syphilis and Neurosyphilis

Abstract

Syphilis is an infectious disease caused by Treponema pallidum. Often known as the "great imitator," it has periods of active disease and periods of latency. Serologic syphilis testing can be divided into treponemal and non-treponemal tests, and multiple tests are required to prove infection. Standardized algorithms exist for syphilis testing and diagnosis. Neurosyphilis, which is often the result of the progression of untreated syphilis, can be life-threatening and requires intravenous antibiotics. Despite the significant challenge of diagnosing and treating neurosyphilis, there are no standardized testing algorithms available. Typically, the cerebral spinal fluid (CSF) venereal disease research laboratory (VDRL) test is considered the gold standard despite low sensitivity. The CSF fluorescent treponemal antibody absorption (FTA-ABS) test is more sensitive despite being less specific and is often the better testing option. This case illustrates a patient with a clinical presentation strongly suggestive of neurosyphilis despite negative initial lab testing and argues for the emergence of a standardized algorithm to guide clinicians.

Keywords: fta-abs; neurosyphilis; syphilis; treponema pallidum; vdrl.

Figure 1. Echocardiogram showing mild global hypokinesis of the left ventricle, mild concentric left ventricular hypertrophy, and hyperechoic myocardium with no major valve insufficiencies.

Figure 2. Computed tomography without intravenous contrast showing chronic changes included an infarct involving the right lateral basal ganglia, sub-insular white matter, and right frontal periventricular white matter with associated volume loss with ex vacuo dilatation of the frontal horn of the right lateral ventricle.

There are also scattered areas of hypodensity within the white matter of both cerebral hemispheres that are nonspecific.

Figure 3. Magnetic resonance imaging without intravenous contrast was limited due to motion and was negative for stroke, mass, and intracranial bleeding.

It revealed the same chronic infarct involving the lateral right basal ganglia as previously noted on head CT one week earlier.