Dictionary

streptococcus, group A See Streptococcus pyogenes.

streptococcus, group B A major cause of infections, including those involving pregnant women and newborn infants. Group B strep can infect the mother’s uterus, placenta, and urinary tract; in fact, it is present in the vagina of around 10 to 25 percent of all pregnant women. Group B strep can be transferred between heterosexual couples…

Streptococcus faecalis An old name for Enterococcus faecalis.

Streptococcus haemolyticus See Streptococcus pyogenes.

Streptococcus pneumoniae The most common cause of bacterial pneumonia and middle ear infection (otitis media) and the third most frequent cause of bacterial meningitis. Also known as pneumococcus.

Streptococcus pyogenes The bacterial cause of strep throat (streptococcal pharyngitis), impetigo, rheumatic fever, scarlet fever, glomerulonephritis, invasive fasciitis, strep skin infections, and rheumatic fever. Also known as Streptococcus haemolyticus and group A streptococcus. See also PANDAS; rheumatic fever; strep throat; streptococcus; Sydenham chorea.

stricture 1 An abnormal narrowing of a body passage, especially a tube or a canal. A stricture may be due, for example, to scar tissue or a tumor. 2 The process of narrowing a body passage.

The condition you’re describing is known as a stroke or cerebrovascular accident (CVA). A stroke occurs when blood flow to a part of the brain is interrupted, either by a blockage (ischemic stroke) or by the rupture of a blood vessel (hemorrhagic stroke), leading to the death of brain cells due to a lack of…

stroke prevention Methods of preventing the occurrence of a cerebrovascular accident. If a person has a transient ischemic attack (TIA), a neurological event with the symptoms of a stroke, the symptoms go away within a short period of time. TIAs are often caused by narrowing or ulceration of the carotid arteries, however, and if that…

stroke volume The amount of blood pumped by the left ventricle of the heart in one contraction. The stroke volume is not all the blood contained in the left ventricle; normally, only about two-thirds of the blood in the ventricle is expelled with each beat. Together with the heart rate, the stroke volume determines the…

study 1 A procedure or an examination. 2 A research project.

Sturge-Weber syndrome A congenital, but not inherited, disorder that affects the skin, the neurological system, and sometimes the eyes and internal organs. The main sign of Sturge-Weber syndrome is a port-wine stain birthmark. Neurological symptoms of Sturge-Weber syndrome may include seizures and developmental delay. See also portwine stain.