Multiple sclerosis and demyelination

Demyelination is characterised by destruction of normal myelin and can be either primary or secondary. Multiple sclerosis is the most common primary demyelinating disease. The disease commonly affects females with a mean age of onset of about 30 years. It is characterised clinically by relapses and remissions of neurological disturbance. The aetiology is multifactorial with gender, genetic and environmental factors contributing to disease susceptibility. The diagnosis remains clinical and confirmation is by histological examination of tissue obtained from multiple sites within the nervous system. Grossly, the brain shows numerous plaques scattered throughout the white and grey matter. The basic lesion on histology is the ‘demyelinated plaque’ with preserved axons set in a gliotic matrix. However, various other lesion types and patterns of demyelination are also identified histologically. Current research is investigating the role of stem cells and oligodendrocyte progenitors, and their potential in the repair of surviving axons.