Neurosyphilis Masquerading as Herpes Encephalitis

Classic presentations of neurosyphilis, such as tabes dorsalis and general paresis, are rare today. Instead, neurosyphilis can present with a spectrum of diverse clinical manifestations. Therefore, neurosyphilis should be considered in the differential diagnosis of all patients with unexplained neurologic deficit or encephalitis. We report a patient who had a nonbloody spinal fluid venereal disease research laboratory titer of 1:32, but presented with a clinical syndrome, MRI findings, and an electroencephalogram (EEG) pattern consistent with herpes simplex encephalitis. Admission spinal fluid PCR for herpes simplex viruses 1 and 2 was negative in 2 reference laboratories.