Pericardial effusion is the buildup of extra fluid in the space around the heart. If too much fluid builds up, it can put pressure on the heart. This can prevent it from pumping normally.

In parotid duct obstruction, part of your parotid duct becomes blocked. As a result, saliva can't flow normally from your parotid gland into your mouth.

Neuronal and mixed neuronal-glial tumors are a group of rare tumors that occur in the brain or spinal cord.

Prion diseases comprise several conditions. A prion is a type of protein that can trigger normal proteins in the brain to fold abnormally. Prion diseases can affect both humans and animals and are sometimes transmitted to humans by infected meat products. The most common form of prion disease that affects humans is Creutzfeldt-Jakob disease (CJD).

Neurogenic bowel is the loss of normal bowel function. It’s caused by a nerve problem. Here's what you need to know about this condition.

Nasal polyps are abnormal, soft, swollen, sac-like growths of inflamed tissue. They line the inside of your nose or your sinuses.

Mitral valve regurgitation is when the mitral valve in the heart is leaky. Read on to learn details about this condition, including causes, risk factors, symptoms, diagnosis, and treatment.

Microscopic polyangiitis (MPA) is a condition that causes small blood vessels to be inflamed. It's a rare type of vasculitis. The disease can damage the blood vessels and cause problems in organs around the body. Read on to learn about causes, symptoms, diagnosis, and treatment.

Medulloblastoma is a type of brain cancer. It most often affects children, but it can also happen in adults. These tumors often grow in the cerebellum, the part of the brain that controls balance and coordination.

McArdle disease is a rare muscle disorder. In McArdle disease, the muscle cells can’t effectively store energy. Read on to learn more.