### Patient Information
A previously healthy 17-year-old boy presented with a two-week history of involuntary muscle jerks (myoclonus) affecting his right thumb and middle finger. Over subsequent days, he developed right upper extremity focal seizures that secondarily generalized, prompting emergent medical evaluation. There was no recent history of trauma, febrile illness, or prior neurological disorder. Routine and confidential psychosocial history taking using the HEADSS assessment (Home, Education, Eating and Exercise, Activities, Drugs, Sexuality, Suicide, and Sleep) revealed that the patient was sexually active, having one female sexual partner. No prior sexually transmitted infection (STI) diagnoses were reported, and the patient denied illicit drug use or other potential seizure triggers.
### Diagnosis
Given the patient’s focal neurological symptoms and sexual history, an infectious etiology involving the central nervous system (CNS) was considered. Initial laboratory screening included a rapid plasma reagin (RPR) test, which returned reactive. Subsequent confirmatory treponemal-specific antibody testing was positive for syphilis. Cerebrospinal fluid (CSF) analysis obtained via lumbar puncture revealed syphilis-specific antibodies and supportive inflammatory markers, confirming a diagnosis of neurosyphilis. Neuroimaging studies were inconclusive, consistent with the known variable presentation of neurosyphilis.
### Differential Diagnosis
The differential diagnosis considered included:
– **Idiopathic focal epilepsy:** Ruled out by the presence of serologic evidence for syphilis and CSF findings.
– **Autoimmune encephalitis:** CSF did not reveal autoantibodies, and clinical course suggested infectious etiology.
– **Viral encephalitis (e.g., herpes simplex virus):** Negative viral PCR and serology.
– **Structural brain lesions (tumors, vascular malformations):** Brain MRI was normal.
– **Other CNS infections (e.g., Lyme disease, tuberculosis):** Serologies and clinical context were not supportive.
### Treatment and Management
The patient was treated with intravenous aqueous penicillin G as per current neurosyphilis treatment guidelines—18–24 million units daily divided every 4 hours for 10–14 days. Supportive care included seizure control with antiepileptic drugs initiated during acute presentation. Close multidisciplinary follow-up with infectious disease and neurology teams ensured monitoring for treatment response and neurological status. Confidential counseling on sexual health and safe sex practices were provided.
### Outcome and Prognosis
Following antibiotic therapy, the patient’s seizures and myoclonus ceased, with gradual neurological improvement over weeks. Repeat CSF examination after therapy showed declining RPR titers indicative of treatment response. Long-term neurological sequelae were minimal, though ongoing monitoring was advised given the potential for delayed complications. The patient was engaged in comprehensive STI education to mitigate risk of future infections.
### Discussion
Neurosyphilis, caused by invasion of Treponema pallidum into the CNS, can manifest during any stage of untreated syphilis infection. Its clinical presentation is notoriously diverse, earning the epithet “the great imitator.” In the postantibiotic era, neurosyphilis is rare, especially in children and HIV-negative populations, but recent epidemiologic data have shown resurgent syphilis incidence worldwide, emphasizing renewed vigilance.
This case highlights the critical role of confidential psychosocial history-taking using validated assessments such as HEADSS in adolescent patients, facilitating timely STI screening and diagnosis. The subtle presentation of focal seizures and myoclonus in a young person without classical signs of syphilis underscores the necessity of including neurosyphilis in differential diagnosis when unexplained neurological symptoms present in sexually active adolescents.
Current guidelines recommend that adolescents at risk undergo regular syphilis screening, particularly when they have neurological manifestations. Early diagnosis and prompt treatment with intravenous penicillin remain the cornerstone to prevent irreversible neurological damage. The interdisciplinary approach combining neurology, infectious disease, and adolescent medicine optimizes outcomes.
In conclusion, this case reinforces the importance of maintaining a broad differential diagnosis in adolescent neurology and integrating comprehensive social and sexual history taking into clinical practice. It also serves as a call for increased awareness of neurosyphilis despite its rarity, given the potential for significant morbidity if left untreated.
### References
1. Workowski KA, Bachmann LH, Chan PA, et al. Sexually transmitted infections treatment guidelines, 2021. MMWR Recomm Rep. 2021;70(4):1–187.
2. Ghanem KG. Neurosyphilis: a historical perspective and review. CNS Neurosci Ther. 2010;16(5):e157–e168.
3. Marra CM. Neurosyphilis. Continuum (Minneap Minn). 2015 Aug;21(4 Neuroinfectious Disease):1714-1728.
4. Golden MR, Marra CM, Holmes KK. Update on syphilis diagnosis and treatment. UpToDate. 2023.
5. Hagan JF, Shaw JS, Duncan PM, editors. Bright Futures: Guidelines for Health Supervision of Infants, Children, and Adolescents. 4th ed. American Academy of Pediatrics; 2017.
