Secondhand smoke is the smoke you're exposed to when someone nearby is smoking. It includes the smoke breathed out by the smoker. And it includes the smoke given off by the burning tobacco.

Learn details about post-polio syndrome, including causes, symptoms, diagnosis, and treatment.

Brown syndrome is a problem with a tendon that attaches to the eyeball. Most cases are congenital, which means they are present at birth. Here's what you need to know about this condition.

A Baker's cyst (popliteal cyst) is a fluid-filled sac that forms behind the knee.

An arachnoid cyst is a fluid-filled sac of the brain or spinal cord. It forms between the brain or spinal cord and the arachnoid membrane. An arachnoid cyst contains cerebrospinal fluid (CSF). These cysts appear most often in children, but they may also occur in adults.

Tongue-tie (ankyloglossia) is a problem with the frenulum, the thin strip of tissue under the tongue. It connects from the underside of the tongue to the floor of the mouth. Some children are born with a frenulum that is too short and tight. This can cause problems with speech and eating.

You may need to take more anti-rejection medicine or take it more often.

Acute bacterial rhinosinusitis (ABRS) is an infection of your nasal cavity and sinuses. It's caused by bacteria. Acute means that you've had symptoms for less than 12 weeks.

A look at treatment and prevention of ear barotrauma. This type of ear damage is caused by a difference in pressure between the inside of the ear and the air around you.

A cardiologist will treat your child. Treatment helps prevent the abnormal heartbeat.