In November 2013, following a febrile episode lasting for one week, a 51-year-old male reported fatigue and increasing clumsiness and rigidity of lower limbs. Two months after the symptoms onset, neurological examination showed ataxic-spastic gait, diffuse accentuation of deep tendon reflexes with extensor plantar response and abolition of the abdominal reflexes. The clinical suspicion of an autoimmune para-infectious myelo-neuropathy, prompted us to a comprehensive clinical chemistry, hematology and autoimmunity work-up: the only pathological result was an IgG monoclonal gammopathy. Nerve conduction studies showed a very mild sensory neuropathy, while visual evoked potentials were abnormal. Contrast magnetic resonance imaging showed a contrast-free parenchymal C2 spinal cord lesion. Cerebrospinal fluid examination, obtained to rule out multiple sclerosis (MS), demonstrated a moderate barrier disruption without oligoclonal bands reaction. These features rule out MS suggesting Devic's disease (neuromyelitis optica). Additional serological testing to detect aquaporin-4 antibodies (NMO-IgG) was positive, underscoring the paramount importance of laboratory testing in this differential diagnosis.
