Dictionary

hypoglossal nerve The twelfth cranial nerve, which supplies the muscles of the tongue.

hypochondroplasia A type of short-limb dwarfism, with shortening especially of the ends of the limbs. A child with hypochondroplasia usually has a prominent forehead, mildly shortened extremities and digits, limited range of motion at the elbows, and inward curvature of the lower back. Diagnosis is made through physical examination and X-rays. Hypochondroplasia is inherited in…

hypochondria The condition of being obsessed with imaginary medical complaints. A person with hypochondria tends to misinterpret minor physical changes as symptoms of major illness. It is closely related to, and may be a subtype of, obsessivecompulsive disorder. Treatment with antidepressant medication and/or cognitive behavioral therapy is often successful. See also obsessive-compulsive disorder.

hypocalcemia Lower-than-normal level of calcium in the blood, which makes the nervous system highly irritable, as evidenced by tetany (spasms of the hands and feet, muscle cramps, abdominal cramps, and overly active reflexes). Chronic hypocalcemia contributes to poor mineralization of bones, soft bones (osteomalacia), and osteoporosis. In children, hypocalcemia leads to rickets and impaired growth….

hypo- Prefix meaning low, under, beneath, down, or below normal, as in hypoglycemia (low blood sugar) and hyposensitivity (undersensitivity). The opposite of hypo- is hyper-.

hyperventilation Overbreathing. Hyperventilation causes dizziness, lightheadedness, a sense of unsteadiness, and tingling around the mouth and fingertips. Hyperventilation can be severe enough to mimic the early warning symptoms of a heart attack, and is therefore a common cause of emergency room visits in the US. Hyperventilation is common and normal after aerobic exercise. Hyperventilation can…

hyperuricemia Abnormally elevated uric acid in the blood. Uric acid is a breakdown product of purines, which are part of many foods. Hyperuricemia may indicate an increased risk of gout, but many patients with hyperuricemia do not develop gout, and some patients with repeated gout attacks have normal or low blood uric acid levels. Hyperuricemia…

hypertrophy, benign prostatic See benign prostatic hyperplasia.

hypertrophy Enlargement or overgrowth of an organ or part of the body due to the increased size of the constituent cells.

hypertrophic cardiomyopathy See cardiomyopathy, hypertrophic.

hypertonic solution A solution that contains more dissolved particles (such as salt and other electrolytes) than is found in normal cells and blood. For example, hypertonic solutions are used for soaking wounds.

hypertonia Increased tightness of muscle tone and reduced capacity of the muscle to stretch caused by damage to the motor nerve pathways in the central nervous system. Untreated hypertonia can lead to loss of function and deformity. Treatment can include physical and/or occupational therapy or medications. Injections of botulism toxin (botox) are sometimes used in…