Neurosyphilis is a serious complication that arises when the bacterium Treponema pallidum, responsible for syphilis, invades the central nervous system. This infection can affect the brain, spinal cord, or the protective membranes surrounding them, known as the meninges. While syphilis itself is a sexually transmitted infection, neurosyphilis represents a distinct and potentially life-threatening progression that can lead to severe neurological and psychiatric issues.
How Syphilis Leads to Neurosyphilis
Syphilis progresses through distinct stages if left untreated: primary, secondary, latent, and tertiary. During the latent stage, the bacteria remain in the body without causing visible symptoms, a period that can last for many years. While neurosyphilis can occur at any point after the initial infection, tertiary neurosyphilis is a late manifestation, often developing 10 to 30 years after the initial infection. The bacteria invade the central nervous system, leading to inflammation and damage to brain tissue, blood vessels, and nerve pathways.
Recognizing Tertiary Neurosyphilis
Tertiary neurosyphilis can present with a wide range of severe neurological and psychiatric symptoms, reflecting the extensive damage the bacteria inflict on the central nervous system. One form, General Paresis, involves a slow degeneration of the brain, leading to cognitive decline, dementia, and significant personality changes. Individuals may exhibit psychiatric symptoms such as delusions, hallucinations, and severe mood swings, progressing to the point of being bedridden.
Another distinct manifestation is Tabes Dorsalis, which primarily affects the posterior columns of the spinal cord. This leads to sensory disturbances like “lightning pains”—sharp, sudden pains in the limbs or abdomen—and a loss of proprioception, the sense of body position. Patients may experience ataxia, an uncoordinated and unbalanced gait, along with bladder control issues and the presence of Argyll Robertson pupils, which constrict when focusing on a near object but do not react to light.
Meningovascular neurosyphilis arises from inflammation of the blood vessels supplying the central nervous system, which can lead to blood clots and block blood flow to brain tissue. This can result in stroke-like symptoms, seizures, and other neurological deficits depending on the affected brain regions. Additionally, tertiary neurosyphilis can involve sensory organs, causing ocular syphilis, which may lead to vision loss, or otosyphilis, affecting the vestibulocochlear nerve and resulting in hearing loss, tinnitus, or vertigo.
Diagnosing and Treating Neurosyphilis
Diagnosis of neurosyphilis involves clinical evaluation, blood tests, and cerebrospinal fluid (CSF) analysis. A lumbar puncture collects CSF from the lower back to examine it for signs of infection. CSF analysis often reveals an elevated white blood cell count (pleocytosis), increased protein levels, and a positive CSF-VDRL (Venereal Disease Research Laboratory) test. While CSF-VDRL is highly specific, other tests like CSF-FTA-ABS may be used if sensitivity is a concern.
Blood tests, such as RPR (Rapid Plasma Reagin), VDRL, FTA-ABS (Fluorescent Treponemal Antibody Absorption), and TP-PA (Treponema Pallidum Particle Agglutination Assay), are also performed to detect antibodies against the syphilis bacterium. These blood tests indicate a syphilis infection, but the lumbar puncture is necessary to confirm central nervous system involvement. Neuroimaging techniques like MRI or CT scans can help identify structural abnormalities in the brain or spinal cord.
Treatment for neurosyphilis is high-dose intravenous penicillin G, administered for 10 to 14 days. This regimen ensures sufficient antibiotic levels reach the central nervous system to eradicate the infection. For individuals with penicillin allergies, desensitization to penicillin is preferred, though alternatives like ceftriaxone are considered. Early diagnosis and treatment can halt disease progression and sometimes reverse symptoms; however, existing neurological damage may not always be fully reversible. Follow-up CSF examinations are recommended every six months until the cell count normalizes to ensure treatment success.