Clinically Isolated Syndrome (CIS) is the first episode of neurological symptoms with demyelination on MRI. Typical symptoms for CIS are optic neuritis, painful loss of visual acuity, patchy brainstem symptoms, such as vertigo, facial numbness or diplopia, or patchy transverse myelitis with tingling paresthesias, or heaviness in a leg or arm. CIS patients with abnormal MRI scans are at higher risk for developing clinically definite multiple sclerosis.
Neuromyelitis Optica (NMO) is another autoimmune demyelinating disease of the central nervous system disease that differs from the most common form, multiple sclerosis (MS). The inflammatory attack here is limited to the optic nerves and the spinal cord. Patients develop loss of vision or transverse myelitis, an inflammatory spinal cord injury. Unlike MS patients, they often have a severe attack and do not fully recover. 80% of patients relapse and 60% of them do so in the first year, so this is a very active disease process with early disability.
Unlike in MS, a specific antibody has been found that correlates with NMO disease course. It binds to aquaporin 4 which is the main water channel in the central nervous system and is called the NMO antibody. Finding an antibody can be used to diagnose and follow the disease course. Since relapses are severe, patients need treatment which is different than the medications we use for typical multiple sclerosis. We need to see these patients early and get them on appropriate treatment and closely following their response.
Optic neuritis is inflammatory demyelination of the optic nerve. Patients present with painful loss of vision in one eye. The visual loss gradually develops over several days and pain occurs around the orbit and with eye movement. Visual function begins to improve over several weeks and usually returns to normal by 3 months. Color vision is the last to return.
In 20-30% of optic neuritis patients, this is the first presentation of multiple sclerosis. 50% of multiple sclerosis patients have an episode of optic neuritis at some time in their disease course. Other etiologies include infections, like syphilis and Lyme, sarcoid, or autoimmune processes like lupus. MRI scanning is helpful in differentiating those patients who are more likely to go on and develop multiple sclerosis.
Transverse myelitis is inflammation localized to the spinal cord. It occurs across a segment, like cervical or thoracic level. It causes injury to spinal cord so that patients present with weakness, sensory and autonomic symptoms below the level of the inflammation.
The degree of inflammation can vary. Patients develop severe inflammatory transverse myelitis in an idiopathic disorder, vascular occlusions and NMO, neuromyelitis optica. The inflammation damages the myelin and the axons resulting in paralysis and sensory loss below the level and loss of bowel and bladder control.
Patchy inflammation in the spinal cord causes mild sensory symptoms, heaviness in the legs or spasticity in patients with more typical multiple sclerosis. The inflammation here causes limited myelin damage with better preservation of the axons.
Early evaluation, through the use of MRI scans, physical examinations, and blood tests to differentiate the different types of transverse myelitis, is key to providing the patient the most effective treatment to improve their condition and prevent further relapses.