This disorder falls into the category of demyelinating disease and tends to be restricted to the central nervous system. There is an increased incidence in northern latitudes and this illness have been of particular interest to epidemiologists as they try to solve the riddle of its association with certain locales, genetic predisposition, and possible association with a viral infection. There appears to be a genetic susceptibility to this illness on an autoimmune basis which remains quite puzzling and probably helps to explain some clustering of the disease in certain locales and in certain families. The illness can be quite benign and there can be a presentation reflective of multiple sclerosis (MS) which never appears again and has been termed clinically isolated syndrome. It has been theorized that the subtle manifestations seen in some patients explains why up to 5% of patients never are diagnosed with the disease during their lifetime but that have characteristic pathology if found when an autopsy is performed for other reasons.
The most commonly affected patient is a young woman in her teens, 20’s or 30’s and there appears to be a predilection for certain Caucasians such as those of northern European descent. However, males, African-Americans and older individuals are certainly susceptible to this disorder and it has become increasingly more readily identified with the availability of MRI brain scans which are particularly sensitive to the white matter lesions termed plaques.
Multiple sclerosis can present in a number of ways. It is suspected in inflammatory disease of the optic disc with secondary sudden visual loss termed optic neuritis. It is not uncommonly associated with double vision, slurred speech, weakness, numbness, incoordination or difficulty with bladder function. It can affect particular areas of the central nervous system such as the brainstem, cerebellum or spinal cord. There can be primary involvement of the spinal cord called transverse myelitis resulting in weakness and loss of sensation below the area of involvement. There can also be associated cognitive and behavioral effects. The MRI scan of the affected area is the initial imaging approach and the MRI brain scan is 90 to 95% sensitive for detecting white matter lesions compatible with MS in patients with presumptive MS. However, despite its sensitivity, the MRI is not overly specific as there are a number of illnesses which can mimic MS such as neurosarcoidosis, Neurobehcet’s disease, systemic lupus erythematosus, and other inflammatory disorders. Additional diagnostic testing may be warranted and this might include a cerebrospinal fluid exam via lumbar puncture also known as a spinal tap. This has particular value especially in questionable cases. There are specific tests which have particular value for the detection of MS in the spinal fluid with the presence of specific protein components, termed oligoclonal bands, present in up to 90% or more of patients with MS.
The potential diagnosis of MS may fall into one of four categories: (1) definitely not (2) possible MS (3) probable MS and (4) definitively MS. Naturally, one would want have a diagnosis at least in the probable category prior to embarking on long-term therapy designed to keep the illness “quiet”, i.e., free of exacerbations. The most common clinical presentation of MS is a so-called relapsing and remitting course characterized by exacerbations followed by remissions. In the acute setting of an exacerbation, intravenous steroid is often administered in an effort to accelerate the remission of an acute attack of central nervous system dysfunction.
Evoked response testing of the conduction velocity of the central nervous system in reference to visual transmission, auditory transmission and transmission of sensory stimulation may also be performed in certain settings. Not all presentations of MS are clearly defined and additional testing to help to either confirm or refute the diagnosis can be of great value in reassuring the patient one way or the other. The treatments for MS that are now available are in the immunomodulating category designed to promote remission of the disorder by suppressing the autoimmune nature of the disease. The initial agents released for MS included beta-interferons (Avonex, Rebif or Betaseron) as well as glatiramer acetate (Copaxone). These are now well established and relatively safe therapies but they require regular injections either weekly, thrice weekly, every other day or daily. The injections are either subcutaneous or intramuscular and require special instruction for the patient or caregiver. Newer oral agents include fingolimid (Gilenya), dimethyl fumarate (Tecfidera) or teriflunomide (Aubagio). These agents are generally much more convenient for the patient but their true safety profile has not been as convincingly demonstrated in view of their more recent availability. An example of how this might be of some concern is the agent natalizumab (Tysabri) which was released with great fanfare because of its reported efficacy. However, it was subsequently found to promote a potentially fatal opportunistic brain infection complication called progressive multifocal leukoencephalopathy. This led the FDA to temporarily suspend release of this agent for a period of time until the potential risks versus benefits could be more adequately determined with newer guidelines for its use. The trials and tribulations of this agent demonstrate the balance that one must try to achieve in an effort to suppress the disease activity through suppression of the immune system but not to the extent that the immune system’s function is reduced to the point that that opportunistic infection or malignancy might occur as a complication of such therapy.
Tulane neurologists are very experienced in the evaluation and management of multiple sclerosis with Drs. Patricia Colon, Roger Kelley, John Freiberg, Maike Blaya and Morteza Shamsnia readily available for such expertise.
Tulane University, New Orleans, LA 70118 504-865-5000 firstname.lastname@example.org