General Introduction: What Is Progressive Multiple Sclerosis?

Over the past decade major advances in multiple sclerosis (MS) therapies have occurred, as well as significant increases in our understanding of disease aetiology: over a hundred susceptibility genes have been identified, complex immunological pathways have been mapped out and rapid changes in imaging techniques have vastly added to our understanding of temporal changes occurring in the course of the disease. Numerous large scale drug trials have been conducted and increasingly efficacious treatment options are emerging with effects on relapse frequency, allowing the clinician an array of therapeutic options. Indeed for patients with relapsing and remitting disease, therapies are offering the real prospect of significant disease modification with reduction in disease burden and disability [1]. Yet despite these advances, treatments for those with progressive MS remain limited and, once established, current drug therapies have little influence on the disease course of progressive MS. Patients with progressive disease are often frustrated by the lack of effective disease modifying therapies and often feel ‘left behind’ when compared to the range of treatments being offered to relapsing patients. This is an understandable frustration and one which is often difficult for patients to comprehend. Having said that, knowledge concerning the disease mechanisms is burgeoning and many research groups are starting to develop strategies to treat disease progression. As time goes on, a clearer understanding of exactly what needs to be treated is becoming apparent and improved trial protocols are being developed. At the heart of such strategies is an increasing knowledge of the pathophysiology of disease progression. The second edition of Progressive Multiple Sclerosis will review the current state of knowledge concerning disease progression and put it in the context of developing and future therapies for this particular phase of MS. To set the scene, in this chapter some general features of MS will be discussed and definitions and clinical characteristics of progressive MS will be presented.