In neuromyelitis optica (NMO) the spinal cord lesions are more frequently present in the cervical and the upper thoracic spinal cord than the lower thoracic and lumbar regions.

The main differential diagnosis of NMO is multiple sclerosis (MS), especially if the disease is limited to the optic nerves and spinal cord. It is very important to differentiate these two conditions because their prognosis and therapy are different, as some MS therapies can exacerbate NMO