Known since the 19th century, neuromyelitis optica (NMO), or Devic's disease, is an idiopathic immune-mediated inflammatory demyelinating disease of the central nervous system selectively affecting the optic nerve and spinal cord. Commonly diagnosed in demyelinating diseases reference centers, we report an 18-year-old female patient who sought medical attention with a 3-month history of weight loss, headache, and vomiting, followed by diplopia, a burning sensation over the lower limbs, and difficulty walking. A few days prior to hospital admission, the muscle strength in her lower limbs became worse and ascended to the upper limbs associated with sensory changes in the trunk and voiding dysfunction. At admission, the neurological examination was consistent with a spinal cord syndrome. After few days of hospitalization, she was tetraplegic with severe signs of brainstem involvement requiring mechanical ventilatory support. Intravenous methylprednisolone and cyclophosphamide were promptly started after ruling out the diagnosis of infectious disease and cord compression. Due to no substantial early improvement, intravenous immunoglobulin was also used. From then on, the neurological status gradually improved. Magnetic resonance imaging showed extensive demyelinating features in the spinal cord, and the serum IgG autoantibody was negative. The patient was referred to a tertiary neurological reference center where she remains under treatment.