Neurosyphilis

Neurosyphilis is an infectious disorder of the central nervous system caused by Treponema pallidum that can produce neuropsychiatric and multisystemic manifestations. A distinctive presentation may include progressive personality or behavioural change with cognitive decline, psychosis or mood symptoms, neurological findings, and characteristic syphilitic features such as a rash, lymphadenopathy, or ocular or auditory findings.

Exposure clues may include a history of sexual exposure associated with syphilis transmission, particularly multiple or new sexual partners, condomless sexual contact, or a partner with syphilis. Risk is increased in people with HIV and in populations or settings with higher syphilis prevalence. Neurosyphilis can occur at any stage of syphilis, including after apparently resolved or untreated earlier infection, so the absence of a recognized recent syphilis infection does not exclude it.

It can present with psychiatric features such as personality or behavioural change, irritability, emotional lability, depression, anxiety, mania, impaired concentration, memory impairment, and progressive cognitive decline. Psychosis is particularly associated with late neurosyphilis/general paresis, but can occasionally occur in earlier or atypical forms of neurosyphilis. Psychotic symptoms, including hallucinations and delusions, may be prominent or presenting manifestations and can resemble a primary psychotic disorder.

Other characteristic features include headache, meningism, cranial neuropathies, seizures, gait disturbance, ataxia, dysarthria, sensory abnormalities, hyperreflexia, and pupillary abnormalities, particularly the classic Argyll Robertson pupil. General paresis may produce progressive cognitive and behavioural deterioration, while tabes dorsalis may cause sensory ataxia, impaired proprioception, neuropathic or lightning pains, reduced reflexes, and bladder dysfunction. Ocular involvement may include uveitis, optic neuropathy, retinal vasculitis, interstitial keratitis, and visual loss, while otologic involvement may cause sensorineural hearing loss, tinnitus, and vertigo. Less commonly, syphilis may involve the gastrointestinal, hepatobiliary, or renal systems, with manifestations including gastritis or other gastrointestinal lesions, syphilitic hepatitis, proteinuria, or glomerulopathy.

From a multisystemic lens perspective, clinical features in other body systems include (but are not limited to):

• Cardiovascular: Aortitis, aortic aneurysm, coronary ostial disease, and aortic regurgitation, particularly in late syphilis.

• Hematologic: Lymphadenopathy, particularly generalized lymphadenopathy during secondary syphilis.

• Musculoskeletal: Osteitis, periostitis, bone pain, joint involvement, and gummatous lesions of bone or soft tissue.

• Dermatologic: Syphilitic rash, including maculopapular involvement of the palms and soles, mucous patches, condylomata lata, and, in late disease, gummatous lesions.

Early diagnosis is important because untreated neurosyphilis can cause progressive and potentially irreversible neurological and psychiatric injury, while appropriate antibiotic treatment can halt progression and may substantially improve neuropsychiatric manifestations.