R

Definition Renal artery stenosis (RAS, sometimes also called renal artery disease or kidney stenosis) occurs when the two main vessels that deliver blood to the kidneys become stiff or narrowed due to vascular disease. RAS is a type of atherosclerosis or hardening of the arteries, which occurs when fatty cholesterol …

Definition Raynaud’s phenomenon (RP) is a disorder resulting in vasospasm, a particular series of discolorations of the fingers and/or the toes after exposure to changes in temperature (cold or hot) or emotional events. Most people with RP have sensitivity to cold. Skin discoloration occurs because an abnormal spasm of the …

Definition Rectal prolapse is when part of your rectum sticks out through your anus (back passage) to form a lump. The rectum is the last part of your bowel. You may notice the rectal prolapse when you’re having a bowel movement. But it can also happen when you cough or …

Definition Reye’s syndrome is a rare but serious disease that is characterized by cerebral and hepatic impairment that occurs after influenza, a respiratory infection, or chickenpox. Reye’s syndrome mainly affects children and adolescents. It sometimes affects infants, and very rarely affects adults. It appears most often in the wintertime when …

Overview – Rubella Rubella is commonly known as German measles or 3-day measles — is an infection that mostly affects the skin and lymph nodes. It is caused by the rubella virus (not the same virus that causes measles). German measles spreads when people breathe in virus-infected fluid, such as …

Overview – Rotavirus Infection Rotavirus Infection is caused by Rotavirus, a contagious virus that causes diarrhea. It’s the most common cause of diarrhea in infants and children worldwide, resulting in over 215,000 deaths annually. Before the development of a vaccine, most children in the United States had been infected with …

Definition Reflux laryngitis or laryngopharyngeal reflux disease also abbreviated LPR. Digestive acid and enzymes flow upward from the stomach through the esophagus to the level of the vocal folds. This is the same process that causes gastroesophageal reflux disease, or GERD, except that otolaryngologists are preoccupied with its effects at …

Definition of Retinitis Pigmentosa Retinitis pigmentosa (RP) is the name given to a group of inherited eye diseases that affect the retina (the light-sensitive part of the eye). RP causes the breakdown of photoreceptor cells (cells in the retina that detect light). Photoreceptor cells capture and process light helping us …