Understanding multiple sclerosis
What Is It? Multiple sclerosis (MS) is a disabling neurological illness. It affects the brain and spinal cord. The disease is usually progressive. This means it worsens over time. An insulating sheath called myelin normally surrounds nerve cells. Myelin helps to transmit nerve impulses. In MS, the myelin sheath becomes inflamed or damaged. This disrupts or slows nerve impulses. The inflammation leaves areas of scarring called sclerosis.