Dictionary

shunt, ventriculopleural A shunt that is used to drain fluid from the cerebral ventricle into the chest cavity.

Shy-Drager syndrome A progressive disorder of the central and sympathetic nervous systems, also called multiple system atrophy with postural hypotension (an excessive drop in blood pressure when the patient stands up, causing dizziness or momentary blackouts). Symptoms of autonomic nervous system failure, such as constipation, impotence in men, and urinary incontinence, usually predominate early in…

Siamese twins Identical (monozygotic) twins that do not separate fully from one another but remain partially united due to the incomplete division of one fertilized ovum. Such twins are known medically as conjoined twins. Conjoined twins are popularly known as Siamese twins after Chang and Eng, the celebrated conjoined Chinese twins born in Siam (Thailand)…

sibling A brother or sister.

sibship The relationship between the children born to a set of parents.

sicca syndrome See Sjögren syndrome.

sick sinus syndrome A condition that features symptoms including dizziness, confusion, fainting, and heart failure that is due to a problem with the sinoatrial node (SA node) of the heart, which acts as the body’s natural pacemaker. If the SA node is not functioning normally, the patient usually has an abnormally slow heart rate (bradycardia),…

sickle cell anemia See anemia, sickle cell.

sickle cell disease See anemia, sickle cell.

sickle cell trait The condition in which a person has only one copy of the gene for sickle cell (and is called a sickle heterozygote) but does not have sickle cell disease (which requires two copies of the sickle cell gene). If two people with sickle cell trait mate and have children together, each of…

sickle hemoglobin See hemoglobin S.

sickness, mountain See altitude sickness.