Syphilis
General description
Syphilis, a sexually transmitted disease caused by the bacterium Treponema pallidum, progresses through several stages. Initially, it presents localized symptoms in the first stage, followed by disseminated symptoms affecting the skin, mucous membranes, and lymph nodes in the second stage. After these symptoms subside, the disease enters early latent syphilis, eventually progressing to late latent syphilis and then to the third stage, characterized by systemic symptoms.
Following infection, Treponema pallidum disseminates hematogenously and invades the nervous system, including the cerebrospinal fluid, leading to neurosyphilis. This manifestation of the disease can be classified into meningeal, vasculitic, and parenchymal types. The meningeal type causes meningitis, the vasculitic type leads to vasculitis, and the parenchymal type affects the spinal cord's parenchyma. These types often occur in conjunction, presenting a complex clinical picture.
CNS Gumma
CNS syphilitic gumma is a rare form of late syphilis. It is often necessary to differentiate it from other diseases such as brain tumors because of its nonspecific clinical manifestations and diverse imaging findings.
Temporal pole hyperintensity
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CerebrumTemporal lobeTemporal poleCerebral white matter
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CerebrumFrontal lobeCerebral white matter
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CerebrumInsula
While T2WI high-signal lesions of the temporal pole are recognized imaging findings, it is important to differentiate these from conditions such as Myotonic dystrophy and Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy (CADASIL). In addition to the temporal pole, the frontal lobe and insula are also affected.
Cerebral atrophy
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Cerebrum
Tabes dorsalis
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Spinal cordThoracic spinal cordSpinal white matterPosterior column
Syphilitic meningomyelitis, also known as Tabes dorsalis, shows T2WI long-segment intrinsic spinal cord hyperintensities, most commonly in the dorsal column of thoracic cord.
Optic neuritis
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Optic nerve
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EyeballOptic disc
Optic neuritis caused by syphilis typically results in inflammation of the optic disc and optic perineuritis.
CNS Gumma
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Anywhere in the brain
Syphilitic gummas, appear as focal nodules adjacent to the meninges showing hypointensity on T1WI, hyperintensity on T2WI and DWI. They may also have a dural tail sign, evidence of focal pachymeningitis, and surrounding cerebral edema.
Syphilitic gummas typically exhibit ring enhancement on imaging studies, though homogeneous contrast enhancement may also be observed.
Leptomeningitis
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Leptomenix
If the pathogen disseminates to the meninges, the condition is referred to as syphilitic meningitis. Imaging may reveal focal or diffuse leptomeningeal enhancement. Additionally, contrast enhancement and thickening can also be observed in the leptomeninges adjacent to syphilitic gummas.