Dictionary

mitral prolapse See mitral valve prolapse.

mitral regurgitation Backflow of blood from the left ventricle to the left atrium due to mitral valve insufficiency.

mitral valve A valve in the heart that is situated between the left atrium and the left ventricle. The mitral valve permits blood to flow from the left atrium into the left ventricle, but not in the reverse direction. The mitral valve has two flaps (cusps). It is so named because it looks like a…

mitral valve, aorta, skeleton, and skin syndrome See MASS syndrome.

mitral valve prolapse A common heart valve anomaly affecting 5–10 percent of people that involves prolapse (flopping backwards) of the mitral valve leaflets into the left atrium during contraction of the heart’s ventricles. This sometimes allows leakage of blood through the valve opening (mitral regurgitation). Most people with mitral valve prolapse have no symptoms, however,…

mittelschmerz Pain due to ovulation that usually occurs at the midpoint between the menstrual periods. From the German mittel, meaning “middle,” and schmerz, meaning “pain.”

mixed connective tissue disease A mixture of three diseases of connective tissue (the framework for the cells of the body): systemic lupus erythematosus, scleroderma, and polymyositis. Patients with mixed connective tissue disease typically have features of each of these three component diseases. They also typically have very high blood levels of antinuclear antibodies (ANAs) and…

mixed mania A state of mind that is characterized by symptoms of both mania and depression and is seen in bipolar disorders. Mixed mania is more common in bipolar children and women than in men. A person experiencing mixed mania may feel agitated, angry, irritable, and depressed all at once. Because it combines a high…

MMR Measles, mumps, rubella vaccine, a combination vaccine.

migraine, classic A migraine with an aura. Such migraines account for no more than 20 percent of migraines. See also migraine.

migraine, common A migraine without an aura. This is the most frequent type of migraine, accounting for about 80 to 85 percent of migraines. See also migraine.

migraine, ocular A migraine involving the eyes that results in distortion of visual images, accompanied or followed by headache. An ocular migraine usually affects only one eye at a time. Image distortion generally begins in the center of the image and then moves to one side. Images “gray out” or look wavy, and sight may…