Neuromyelitis optica (NMO) or Devic disease is a rare, autoimmune disease of the central nervous system (CNS). Magnetic resonance imaging (MRI) is the choice of diagnostic method for neuromyelitis optica (NMO).
The symptoms and diagnosis of NMO are
- Lesions that mirror the distribution of aquaporin 4, a protein found in the target cells. The sites of the lesion are
- Periventricular (hemispheric) white matter involvement. Ventricles are cavities in the brain.
- Periaqueductal grey matter that lines the ventricles or brain cavities.
- Hypothalamus/medial thalamus (midbrain).
- Dorsal pons/medulla (hindbrain).
- Corpus callosum (tissue connecting two halves of the brain).
- Deep white matter
- Hemispheric white matter lesions
- Larger than 3 centimeters in diameter.
- Radially spindle-shaped.
- Involving the overlying cortex.
- Bright spotty lesions over the spinal MRI are a specific feature of NMO.
The MRI of the spine in people with NMO often reveals inflammation extending over three vertebrae. NMO typically affects the cervical and thoracic areas, especially during a relapse. On the contrary, the spine MRI in people with multiple sclerosis (MS) often reveals inflammation extending over two vertebrae.
What is NMO?
Neuromyelitis optica (NMO) or Devic disease is a rare, autoimmune disease of the central nervous system (CNS). NMO primarily affects the myelin sheath that covers the cells of the CNS. The disease targets the spinal cord, optic nerves and brainstem. The damage to the optic nerves produces swelling and inflammation that cause pain and vision damage. The damage to the spinal cord causes weakness or paralysis in the legs or arms, loss of sensation and problems with bladder and bowel functions. Moreover, damage to the brainstem can lead to prolonged hiccups, nausea, vomiting, vertigo or respiratory failure.
NMO is a relapsing-remitting disease and, during a relapse, new damage to optic nerves and/or the spinal cord can cause additional disability.
There are two types of NMO
- Relapsing form: This is the most common type of NMO and mainly affects more women than men. It has periodic flare-ups with some respite in between.
- Monophasic form: This involves a single attack that lasts for one to two months. Both men and women are equally affected by this form.
What are other ways to diagnose NMO?
To diagnose neuromyelitis optica (NMO), the physician may review the patient’s medical history and physical symptoms and perform a physical examination. The physicians may also use the following tests to diagnose NMO.
- Neurological examination: This is done to examine movement, muscle strength, coordination, sensation and memory and thinking functions. An ophthalmologist may also be involved in the exam.
- Blood test: The doctor may perform a blood test for the autoantibody, NMO-IgG, which helps distinguish NMO from multiple sclerosis (MS) and other neurological conditions.
- Lumbar puncture (spinal tap): In this test, the doctor will insert a needle into the lower back to drain a small amount of spinal fluid. Next, the physician sends the fluid to the lab to test the levels of immune cells, proteins and antibodies. In NMO, the spinal fluid reveals an abnormal level of white blood cells, which is higher than that seen in MS.
- Stimuli response test: The doctor will perform a stimuli response test to learn how well the brain responds to stimuli, such as sound, sight or touch. The physician will attach electrodes to the scalp. In some cases, the physician might also attach electrodes to the earlobes, neck, arm, leg and back. The brain responses to stimuli are recorded in the equipment attached to the electrodes. As a result, the physician can find the lesions or damaged areas in the spinal cord, optic nerve, brain or brainstem.