Medical Edge Newspaper Column

Plasma Exchange: Important New Treatment for MS, But Not a Cure

Jan. 1, 2007
Dear Mayo Clinic:
I have an acquaintance whose multiple sclerosis was more or less "cured" with plasma exchange. Yet Mayo Clinic's Web site says that plasma exchange is used mostly as a last-resort procedure. Why wouldn't you offer it to every MS patient? -- Vulcan, Mich.

Answer:
Although it's good to hear that your acquaintance experienced favorable results with plasma exchange, it is not a cure for multiple sclerosis (MS). A course of plasma-exchange treatments, which typically takes about two weeks, does lower antibody levels -- considered the culprit in some, though not all, patients with MS -- but for less than three months. And there is no convincing evidence that plasma exchange prevents attacks of neurological difficulty, the sudden periods of acute MS symptoms, also known as episodes, or exacerbations that are characteristic of the disease. Furthermore, plasma exchange is not advisable for every patient experiencing such an attack.

Most MS patients respond well to intravenous corticosteroid drugs, such as methylprednisolone (Solu-Medrol), which constitute the first-line treatment for relieving flare-ups. These medications not only are effective most of the time but also are easier, safer and less expensive to administer than plasma exchange, which is reserved as a "rescue" treatment for the under 5 percent or so of patients who manifest very severe symptoms and fail to improve satisfactorily with corticosteroid treatment. Other demyelinating diseases, such as neuromyelitis optica, the symptoms of which overlap with MS, more commonly produce very severe symptoms that require plasma exchange.

MS, a chronic illness that affects the central nervous system, is generally believed to be an autoimmune disease -- the immune system's antibodies and white blood cells attack the brain's myelin (tissue that surrounds nerves) as if it's a foreign substance. This destructive process causes inflammation and injury not only to the myelin sheath itself but also to the underlying nerves, resulting in multiple areas of scarring (sclerosis). Eventually, the damage can slow or block the nerve signals that control coordination, strength, sensation and vision.

Plasma exchange (also called plasmapheresis) is based on the idea that replacing the MS patient's plasma may remove destructive factors, including the antibodies that attack myelin. This procedure involves removing some of the person's blood and mechanically separating the blood cells from the fluid (plasma). The blood cells then are mixed with a replacement protein solution, typically albumin or a synthetic plasma-like fluid, and the new blood-containing solution is returned to the patient's body.

Your acquaintance is likely among the minority of MS patients who had an attack but failed to respond to corticosteroids. For people in this situation, plasma exchange may seem like a godsend. In our research at Mayo Clinic, 42 percent of drug-resistant subjects showed significant improvement with plasma exchange, which compared to a 5 percent response rate among those who received placebo plasma exchange. Please note, however, that plasma exchange has not been demonstrated to be any better than the first-line corticosteroid treatment.

It is better to prevent attacks of MS rather than to try to relieve symptoms after the fact. That's why a common approach now is to treat the patient with "disease-modifying medications" that tend to reduce the frequency of flare-ups -- although these treatments are partially effective and don't work for everyone. The best known among them are interferon beta-1b (Betaseron) and interferon beta-1a (Avonex, Rebif), which are genetically engineered copies of proteins that occur naturally in the body. While these beta interferons help regulate the immune system, it is uncertain which of their many actions leads to a reduction in disease activity and what the extent of their long-term benefits may be. An alternative to beta interferons is glatiramer acetate (Copaxone), which promotes the production of certain proteins, called cytokines, that can reduce the intensity of inflammation in the brain. All of these drugs are administered by injection.

Unfortunately, there is no cure for MS as yet. Plasma exchange is an important new way of limiting the consequences of severe attacks when standard treatments fail.

-- Brian G. Weinshenker, M.D., Neurology, Mayo Clinic, Rochester, Minn.