Leopold Rusizana
Background: Neuromyelitis Optica which is abbreviated as NMO is an autoimmune disease of the central nervous system (CNS) affecting mainly the optic nerves and spinal cord. It is alternatively referred to as Neuromyelitis Optica spectrum disorder or NMOSD. With this rare disorder, the body's immune system mistakenly attacks healthy cells and proteins of the body most often those in the spinal cord and eyes. In NMO, abnormal autoantibodies bind to a protein called aquaporin-4, triggering parts of the immune system hence causing inflammation and damage to cells. This ultimately results in the loss of myelin structures of nerves in the brain and spinal cord.
NMO affects regions of the central nervous system; spinal cord (longitudinally extensive transverse myelitis), optic nerve (optic neuritis), dorsal medulla, brainstem causing acute brainstem syndromes and thalamus/hypothalamus.1 The attacks are commonly severe and most likely the minimum being in less than a week. Longitudinally extensive transverse myelitis (LETM) is the common specific presentation of NMO which is unusual in Multiple Sclerosis. LETM often results in paraplegia or tetraplegia depending on the spinal cord level involved. The sensory level is not rapidly involved which distinguishes NMO from Guillain– Barré syndrome. Intense itching due to inflammation of specific fibers in the spinothalamic tract and tonic spasms increased muscle tone during painful episodes.
Papp V et al (2021) in a systematic review concluded that NMO whose cause has not been clearly understood is a very rare disease worldwide, variations and prevalences have been described among diverse geographic areas and ethnicities. The adult population is more affected by NMO.2 NMO appears to affect blacks than other ethnicities with female blacks more affected than their male counterparts.3 The population prevalence of neuromyelitis optica (NMO) is estimated to be between 0.3 and 4.4 per 100,000.4 Neuromyelitis Optica has no cure but with appropriate management, various symptoms of the disease can be reversed and prevention of future attacks is possible