Neuromyelitis optica (NMO), also known as Devic's disease, is a rare type of demyelinating disease. It is called a demyelinating disease because it occurs when the protective covering (the myelin sheath) that surrounds the nerves in the brain and spinal cord is damaged.
The damage to the myelin sheath causes inflammation (redness and swelling) of the:
- spinal cord - this is called transverse myelitis (TM)
- optic nerve - this is called optic neuritis (ON)
NMO can also affect parts of the brain.
How common is NMO?
NMO is a very rare condition. In Europe, it is estimated that there are less than two cases of NMO for every 100,000 people. The condition is more common in people of Asian and African descent.
NMO can affect anyone, but it is more common in people who are around 40 years of age. The condition varies from person to person, depending on the individual and the type of NMO that they have.
There are two main types of NMO:
Relapsing NMO is the most common type of NMO. After the initial attack of optic neuritis and transverse myelitis, there will be further recurrences, often over a number of years. This can sometimes lead to permanent disability.
Disability occurs because the body cannot always fully recover from the damage that is caused by the attacks on the spinal cord and the optic nerve. Many more women are affected by this type of NMO than men.
Monophasic NMO is where people experience a few attacks in a short space of time - for example, over a few days or weeks, but do not have any further attacks. Equal numbers of men and women experience this form of NMO.
NMO can sometimes be confused with multiple sclerosis (another condition that affects the brain and spinal cord). It is important that the condition is diagnosed correctly because this will affect the treatment.
Several medications are used to treat the different symptoms of NMO. Rehabilitation techniques, such as physiotherapy (when physical methods are used to promote healing), can also help with any reduced mobility that the relapses cause.
The spinal cord is a column of nervous tissue located in the spinal column. It sends messages between the brain and the rest of the body.
The nerve that connects your eye to your brain.
The brain controls thought, memory and emotion. It also sends messages to the body controlling movement, speech and senses.
Inflammation is the body's response to infection, irritation or injury. It causes redness, swelling, pain and sometimes a feeling of heat in the affected area.