Pain and multiple sclerosis: pathophysiology and treatment.

Pain is a common symptom in multiple sclerosis (MS) and has recently been estimated to be experienced by up to 75 % of patients. Pain can be present at any point in the course of the disease and patients may experience pain from various causes simultaneously. Pain in MS can also be secondary to other symptoms, such as spasticity, fatigue, and mood disorder. Of all drug use to treat MS symptoms, treatment for pain accounts for nearly 30 % of total use. At the same time, patients report low satisfaction with pain management. Pain affects quality of life and can influence a person's participation in family life and work and affect mood. Most of the pain literature in the field of MS is based on open-label studies involving small numbers of subjects. Placebo-controlled trials in severe pain syndromes such as trigeminal neuralgia are unethical but for other types of MS-related pain conditions, placebo-controlled trials are ethical and necessary to establish efficacy, particularly given the well-documented placebo effect for various painful conditions This review discusses available data and emphasizes areas of pain research that require further attention.