Response to Penicillin for Presumed Neurosyphilis in a Patient with Human Immunodeficiency Virus (HIV), a Normal CD4 Count, and an Undetectable Viral Load: A Case Report.

BACKGROUND Neurosyphilis is a bacterial infection of the brain and the spinal cord, caused by Treponema pallidum. Its nonspecific clinical presentation includes cognitive impairment and motor and/or sensory function compromise. Neurosyphilis infections in patients with HIV have increased over the past few years and many cases of neurosyphilis manifest in patients with HIV who have low CD4 T-cell counts and high viral loads (VL). However, there is extremely limited acknowledgement in the literature about neurosyphilis presentations in patients with HIV who have normal CD4 counts. CASE REPORT We present a neurosyphilis and HIV coinfection in a patient with a normal CD4 count and an undetectable VL. A 69-year-old woman with a medical history of HIV was on a prescribed antiretroviral treatment regimen. She presented in the Emergency Room in an unresponsive state, although this had been preceded by a period of rapidly progressive cognitive decline. Her brain computed tomography scan without contrast was unremarkable. Laboratory test results were within normal limits, except for a positive result for the microhemagglutination assay for Treponema pallidum antibodies and rapid plasma regain (RPR) test, which was highly suggestive of neurosyphilis as a presumed diagnosis. She showed remarkable clinical improvement after the initiation of conventional treatment for neurosyphilis, which is a 14-day regimen of intravenous penicillin G. CONCLUSIONS Given the broad neurological manifestations of neurosyphilis and its increasing incidence in patients with HIV, it is important to consider neurosyphilis in the differential diagnosis after ruling out other causes of encephalopathy, especially in patients with an undetectable VL and a normal CD4 count.