BackgroundSyphilis is associated with a wide variety of systemic presentations, earning it the moniker “The great mimicker”. Neurosyphilis is classically associated with meningovasculitis in the acute-subacute stage and tabes dorsalis and dementia paralytica in later stages. However, one of the less well described presentations include Guillain–Barre Syndrome. This case presents a patient with an ascending polyneuropathy suspicious for Guillain–Barre Syndrome who also had other atypical findings including a truncal sensory loss, optic disc swelling, and rash ultimately found to have neurosyphilis. Electrodiagnostic testing was consistent with demyelination, supporting a diagnosis of neurosyphilis associated Guillain–Barre Syndrome.Case presentationA 37-year-old female presented to the emergency department with a weakness and difficulty swallowing. She described a three-month history of symptoms, initially starting with a persistent headache followed by one month of a pruritic rash on her chest, palms, and soles. Two weeks prior to presentation, she developed progressive weakness in her arms, numbness in her arms and chest, and difficulty swallowing. Neurological exam was notable for multiple cranial neuropathies, distal predominant weakness in all extremities, length-dependent sensory loss, and hyporeflexia. Investigation revealed a positive Venereal Disease Research Laboratory in her cerebrospinal fluid without significant pleocytosis, contrast enhancement in cranial nerves V, VII, and VIII on MRI, and a demyelinating polyneuropathy on electrodiagnostic testing. She was diagnosed with Guillain–Barre syndrome, secondary to neurosyphilis. The patient acutely declined and required intubation, and ultimately made a full recovery after treatment with plasmapheresis and penicillin.ConclusionsThis case describes a clinical entity of syphilitic Guillain–Barre Syndrome and highlights the importance of including syphilis in the differential of any patient presenting with ascending polyradiculopathy, especially given the resurgence of syphilis.