A 41-year-old man with a 10-year history of HIV was admitted to the hospital after he was found unconscious in his home. His current medication included antiretroviral therapy. Upon awakening, the patient was weak and reported numbness in his upper and lower limbs. Manual muscle testing demonstrated upper and lower limb weakness with decreased sensation to light touch and pinprick below the C5 level. A magnetic resonance image of the spine demonstrated spinal cord edema at C3 through T1 levels, with focal spinal cord enhancement at C6, without spinal cord atrophy (image A and image B, arrows). Rapid plasma reagin, Treponema pallidum hemagglutination assay, and cerebrospinal fluid (CSF) VDRL test results were positive, and syphilitic meningomyelitis was diagnosed. Penicillin G was administered intravenously (24 million U/d for 14 days). Symptoms began to improve after 1 week, and the patient was discharged. 

Syphilitic meningomyelitis represents less than 3% of neurosyphilitic cases.¹ The diagnosis is based on a high CSF white blood cell count (≥20 µL) with either a reactive CSF VDRL test result or a positive CSF intrathecal T pallidum antibody index.¹ In syphilitic meningomyelitis, magnetic resonance imaging of the spinal cord demonstrates centrally long-segment diffuse high-intensity abnormality on T2-weighted images, in contrast to tabes dorsalis, in which the dorsal column would be affected.^2-4 The recommended treatment for patients with syphilitic meningomyelitis is 18 to 24 million U/d of intravenous, aqueous penicillin G for 10 to 14 days.⁵