Neuromyelitis Optica Spectrum Disorder (NMOSD), also known as Devic Disease, is a chronic disorder of the brain and spinal cord dominated by inflammation of the optic nerve (optic neuritis) and inflammation of the spinal cord (myelitis). The characteristic symptoms of NMOSD are either optic neuritis or myelitis; either may occur as the first symptom. Optic neuritis is inflammation of the optic nerve (optic neuritis) leading to pain inside the eye which is rapidly followed by loss of clear vision (acuity). The other cardinal syndrome is inflammation of the spinal cord, a condition known as transverse myelitis because the symptoms tend to affect some, and often all motor, sensory and autonomic functions (bladder and bowel) below a certain level on the body, although, not infrequently, symptoms may be confined to one side of the body. Affected individuals may experience pain in the spine or limbs, and mild to severe paralysis (paraparesis to paraplegia) of the lower limbs, and loss of bowel and bladder control.