Multiple sclerosis (MS) is the most common neurological disorder among young adults. In Belgium, it affects some 15,000 people. It is an auto-immune disease in which the body attacks its own tissues. The immune attack in MS targets the central nervous system, including nerve fibres and the myelin sheath that insulates these fibres as well as the cells that generate nerve impulses and those that produce and sustain the nerve sheath. These lesions are well-localised and are called "plaques".
From a clinical point of view, in most cases the course of the disease can be divided into two distinct phases. The first is characterised by relapses or "flare-ups" and remissions (inflammatory phase); the second by the progressive disappearance of the relapses and by the onset of an irreversible disability which gradually worsens (degenerative phase). More rarely, some patients start with a progressive course and never have a relapse, while others develop only very slight disabilities, even after many years.
The diagnostic is based on a key clinical characteristic of MS, namely its "multiplicity in space" (the occurrence of several lesions) as well as its "multiplicity in time" (unforeseeable occurrence of relapses and remissions). Currently, Magnetic Resonance Imaging (MRI) enables doctors to observe the lesions and to carry out much more accurate diagnosis at a much earlier stage.
For some years now, drugs have been available which counter the inflammatory mechanisms and diminish, to some extent, the frequency and seriousness of the relapses. Current research focuses on medications capable of countering the degenerative processes and slowing down the progression of disability.