engleski

Multiple sclerosis

Multiple sclerosis (MS) is the most common acquired autoimmune demyelinating disease of the central nervous system (CNS) characterized by slowly progression. The cause of MS is not known but is believed to involve 3 factors: genetic vulnerability (inheriting too many susceptibility genes and too few protection genes), some form of exposure to one or more environmental triggers, and the development of pathologic host immune responses directed against the CNS. MS is heterogeneous disease demonstrating clinical variability, based on distinct clinical subtypes and disease severity. Besides subliclinical (asymptomatic) MS, that is based on autopsy studies and may account for up to 20% of MS, the most common clinical (symptomatic) form is relapsing-remitting type of disease, seen in 85% of MS at the onset, and in 55% of overall MS. This type of MS is characterized by disease attacks and clinical stability in between. Much rare is primary progressive subtype and it is seen in 10% of MS. This type of disease is characterized by slow worsening from the onset and distinctive disease onset features ; older age onset, progressive myelopathy, equal gender ratio and no relapses. Five percentages of patients suffer progressive relapsing subtype which is indistinguishable from primary progressive except for superimposed relapses. Secondary progressive subtype develops in prior relapsing patient who transitioned to slow worsening. It is seen in 30% of all MS and ultimately in 90% of untreated relapsing MS. The most important for the diagnosis of MS are clinical criteria. Important are signs of dissemination of the clinical symptoms in the space and time. Although symptoms of MS are various and not unique, some of them are highly characteristic. Development of clinical abnormality in relapsing-remitting course of the disease is, as it is believed, influenced by number of fibers subserving the particular function and the proportion which is blocked by the demyelination, or in other words clinical symptoms appear when the involvement of fibers is more than their “ safety margin” . When demyelination do not exceed safety margin of the nerve conduction, patient is asymptomatic. The correct diagnosis of MS is very important because today it is well known that the best prognosis have patients with the early start of treatment with disease modifying drugs such as interferon beta (IFNb) 1 a, 1 b, and glatiramer acetate (Copaxone). To increase the specifity of diagnosis and to minimize the number of false diagnose, besides clinical, paraclinical criteria are used, the latter involving information obtained from magnetic resonance imaging (MRI), evoked potentials, and cerebrospinal fluid (CSF) analysis. In 85 to 95 % of patients with MS oligoclonal bands (OCB) are found in CSF. OCB represent limited classes of antibodies against unknown antigen, and are unique in individual patient. Isoelectric focusing on agarose gel followed by immunoblotting should be the “ gold standard” for detecting the presence of oligoclonal bands. The presence of OCBs in monosymptomatic patients predicts a significantly higher rate of progression to MS than the absence of bands. As the most patients with MS (80%) initially present with a clinically isolated syndrome (CIS), the symptom highly suggestive on MS, a lot of efforts has been focused in finding the parameters that may predict early conversion in MS. It was found that the presence of serum antibodies against myelin oligodendrocyte glycoprotein (MOG) and myelin basic protein (MBP) in these patients may be such parameters. The presence of MOG and MBP antibodies in patients with CIS predicts the early conversion in MS, and the absence of these antibodies suggests that the patient will remain disease – free for several years. Diagnosis of multiple sclerosis is usually easily diagnosed by using mentioned criteria but the differential diagnosis should be carried out in clinically and /or MRI and CSF atypical findings, and especially in primary progressive course of disease. In that case we have to consider other disorders such as ischemia, systemic lupus erythematosus, Behcet disease, other vasculitides, HTLV-I infection, sarcoidosis, Lyme disease, neurosarcoidosis. Differential diagnosis is most complex at the onset of postinfectious and postvaccinal disseminated encephalomyelitis (DEM), but the nature of some symptoms and/or paraclinical findings may help. Incorrect diagnosis of MS causes great psychological changes to the patient and may lead to unnecessary treatment.

multiple sclerosis; diagnostic criteria; magnetic resonance imaging

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