This report represents a case of post-infections NMOSD relapse due to syphilis. 

A 25-year-old woman was admitted in the emergency room with an acute onset of paresthesia in the upper and lower limbs and an electric shock sensation irradiating to both arms during neck flexion (Lhermitte's sign). She had round hyperchromic papular lesions in the palms and soles, which were painless, non-pruritic and appeared at the same time as the neurological picture. In the neurological examination, she presented sensory ataxic gait, positive Romberg maneuver, dysmetria in the finger-nose test with eyes closed, slight proximal and distal weakness in the left arm, hyperreflexia in all four limbs with bilateral Achilles clonus, apalesthesia with loss of proprioception in the hands, painful anesthesia in the right arm and painful hypoesthesia in the right foot and left leg. She had a previous history of systemic lupus erythematosus since the age of 14, and NMOSD with positive serum anti-AQP4 antibody diagnosed at the age of 23. In the current relapse, serum VDRL was 1:32, CSF was normal, and MRI showed an extensive area of increased signal in cervical cord suggesting longitudinally extensive myelitis. The diagnosis of an acute attack of NMOSD triggered by secondary syphilis (roseola syphilitic) was established. She received one dose of 2.4 million I.U. benzathine penicillin, and methylprednisolone treatment was initiated, with no positive results. Plasmapheresis was then performed, with improvement of the strength, sensibility, and coordination.