Case Presentation: A 72-year-old HIV-negative male with a past medical history of neurosyphilis who received two complete 2-week regimens of IV Penicillin G and one IM Penicillin, was admitted due to a recurrence of blurry vision and gait instability. The patient’s symptoms started with dizziness noted since last year, which then progressed to gait instability associated with increasing falls, headache, floaters and blurry vision. Initial work up was remarkable for a serum RPR that was reactive (1:256). Neurosyphilis was established after CSF analysis demonstrated positive FTA-ABS, reactive VDRL 1:8, glucose 39, protein 103, and WBC 8. He was diagnosed with ocular syphilis as evidenced by vitritis and chorioretinitis. He was treated with IV Penicillin G for 2 weeks. All his symptoms improved after initiation of therapy, however, his symptoms recurred 48 hours after completion of treatment. He was readmitted a month later due to the persistence of symptoms and was treated to another round of IV Penicillin G. Despite improvement in serum RPR titers to > 1:156, he had a similar recurrence of symptoms 2 days after completion of treatment. He was readmitted for a third time. On examination, he had decreased sensation to the right lower extremity below the knee, a wide-based gait, a positive Romberg test, and decreased visual acuity bilaterally. He could not walk in a straight line and had difficulty turning. Extensive workup was done to rule out other diagnoses. Follow-up CSF analysis showed an improvement in CSF pleocytosis, protein, and VDRL 1:4 levels. Serum RPR improved to 1:128. Patient was given his third course of IV Penicillin G for another 2 weeks. There was an improvement in the patient’s clinical symptoms during follow-up.
Discussion: Syphilis is an infection caused by Treponema pallidum. The spirochete invades the central nervous system (CNS) and can present at any phase of the disease as neurosyphilis. Early neurosyphilis manifests as meningitis. On the other hand, late infection is characterized by tabetic or paretic neurosyphilis characterized by ataxia, abnormal sensations, and mood disturbances. T. pallidum can also cause ocular syphilis and otosyphilis. (1–3) Penicillin G is the standard treatment for all stages of syphilis. Penicillin resistance has not been well studied but there are reports of varied single-nucleotide polymorphisms (SNPs) of T. pallidum. (6) There is no gold standard for determining a cure because the direct in-vitro culture of T. pallidum from patient samples remains unsuccessful. (7) Treatment response is the only measure of effectiveness which is a decrease of more than fourfold in titers. Patients can be considered as ‘cured’ after a negative non-specific antibody titer. About 10-20% of patients with early syphilis have treatment failure; there is not enough data on treatment failure with late syphilis or neurosyphilis. (8)
Conclusions: In a patient who presents with a high suspicion of neurosyphilis relapse, close follow-up and careful re-evaluation of the diagnosis, and consideration for re-treatment is imperative.