What Is Multiple Sclerosis?

I'm presently working on an article about multiple sclerosis. It's a difficult disease to write about. The jury's still out on the cause, the cure, even the definition of what multiple sclerosis is.

MS is not a disease of old people. According to recent estimates, the average age of onset is 28 years. Children as young as 2 have been diagnosed with MS. It is progressive, degenerative, irreversible, and incurable. More than 1 out of every 1000 people in the US – over 400,000 people – has multiple sclerosis (MS), according to a study recently published in Neurology. This figure more than 50% higher than that estimated by a similarly large literature review published in 1982. MS is on the rise, and treatments are few.

MS is a disease in which lesions, also called plaques, form in the central nervous system, causing disablility. This disability may take many forms: pain, numbness, fatigue, muscle weakness, vision problems, memory loss, bladder dysfunction, and so on. The lesions--hard, scarred patches--are the result of injury to the myelin sheath around the axons of the nerve cells. Sclerosis is scarring; multiple lesions must be present for the disease to be defined as MS.

MS is characterized by abrupt onset of symptoms. Various clinical courses have been described for MS, leading some doctors to speculate that MS is really several different diseases. Some patients display a pattern of relapses and remissions, often with increasing disability. Others are chronic progressive; still others, chronic static. Uncertainty as to the progression of the disease is one of the factors contributing to depression in people with MS.

MS was long thought to be an autoimmune disease, in which the body, through its immune system, launches a defensive attack against its own tissues, triggering inflammation. However, new research points to a vascular mechanism (one having to do with the blood vessels). All the immune markers investigated in MS have also been found in stroke patients and at the same levels. (Stroke, of course, is blockage or rupture of blood vessels to the brain.)

It is now accepted that MS is characterized by dysfunction of, and damage to, the blood-brain barrier (BBB). The BBB is the tightly-packed formation of endothelial cells on the walls of the capillaries in the brain. Whereas in other parts of the body many substances can pass through the gaps in the endothelial cells, in the brain only a few types of substances can cross the BBB. The BBB protects the brain from many chemicals which flow through the body, and from infections.

In MS, white blood cells called T lymphocytes destroy the myelin. It has been supposed that a malfunctioning autoimmune system was the cause of T cells attacking these protective sheaths. However, we can see that if the BBB is broken down, allowing the white blood cells to enter the brain and cause damage, it is really a vascular and not an autoimmune mechanism operating.

Breakdown of the barrier results in edema (swelling) and associated effects (reperfusion injury, for example). It seems logical that treatments for conditions with similar pathogenesis, like traumatic brain injury, might also be effective for MS. Those who are familiar with the research I've been doing for the last eight months know what treatment I'm referring to: hyperbaric oxygen therapy. To be continued.