Neuromyelitis optica (NMO) can easily be mistaken for a number of other conditions that have similar symptoms. These include:
- multiple sclerosis (MS) - a condition of the central nervous system (the brain and spinal cord), which affects movement and balance
- acute demyelinating encephalomyelitis (ADEM) - an acute (short-term) condition that affects the brain and spinal cord
- Sjogren's syndrome - an autoimmune condition (when the body’s defence system starts attacking the body) that affects the saliva and tear glands
- systemic lupus erythematosis (SLE) - an autoimmune condition that causes joint pain and fatigue (extreme tiredness)
- mixed connective tissue disease (MCTD) - inflammation of the connective tissue (tissues that provides support and structure to other tissues)
- virus induced inflammation - inflammation that is caused by a viral infection
- cancer associated inflammation (paraneoplastic optic neuropathy)
As NMO can be similar to each of these conditions, it can be difficult to diagnose. However, there are a number of diagnostic tests that your GP may carry out in order to rule out any other conditions. You may also be referred to a specialist at a hospital to help with your diagnosis, such as:
- an ophthalmologist - a medical doctor who specialises in eye conditions
- a neurologist - a specialist in conditions of the central nervous system
A sample of your blood may be tested for the presence of the NMO lgG antibody, which is commonly found in people with NMO. An antibody is a protein that is produced by your body to destroy disease-carrying organisms.
If the test is positive, it means that you are at increased risk of experiencing multiple attacks of transverse myelitis (inflammation of the spinal cord).
A lumbar puncture, also known as a spinal tap, is used to collect a small amount of cerebrospinal fluid (CSF). CSF is the clear fluid that surrounds your brain and spinal cord.
The CSF can be tested for white blood cells (cells in the blood that help fight infections) and certain proteins. This will help determine whether you have NMO or another condition.
See the Health A-Z topic about Lumbar puncture for more information.
Magnetic resonance imaging (MRI)
A magnetic resonance imaging (MRI) scan uses strong magnetic fields and radio waves to produce a detailed image of the inside of the body. The procedure scans the brain and the body for any lesions (wounds) that may be present.
Generally, test results for people with NMO show no abnormalities in the brain, but often show lesions over three or more segments of the spinal cord. This type of damage is very unusual in MS, so it is often used to rule this condition out.
See the Health A-Z topic about MRI scan for more information.
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.
The immune system is the body's defence system, which helps protect it from disease, bacteria and viruses.
Antibodies are your body's natural defence against any foreign antigens that enter your blood. An antibody is a protein that is produced by the body to neutralise or destroy disease-carrying organisms and toxins.