A joint dislocation is when there is an abnormal separation between the bones of a joint. When this happens in your ankle joint, it's known as an ankle dislocation. It is a severe injury.

Aniridia is a serious and rare eye disorder in which the iris is partly or completely gone.

Acute bacterial rhinosinusitis (ABRS) is an infection of both your nasal cavity and sinuses. It's caused by bacteria. Here's what you need to know about this condition.

Parkinson disease is a movement disorder that can cause muscles to tighten and become rigid. It can make it hard to walk and engage in daily activities.

Normal pressure hydrocephalus is excess cerebrospinal fluid buildup in the brain ventricles. It may develop from infection, bleeding, injury, or surgery.

Cranial neuropathy is a disorder that causes nerve damage in the nerves that arise from the brain and brainstem. This disorder can affect the ability of the face and eyes to feel and move.

The brachial plexus can be injured in many different ways--from pressure, stress, or being stretched too far. The nerves may also be damaged by cancer or radiation treatment. Sometimes, brachial plexus injuries happen to babies during childbirth.

Huntington disease is a brain disorder that can lead to emotional disturbances, loss of intellectual abilities, and uncontrolled movements.

Cerebral venous sinus thrombosis (CVST) occurs when a blood clot forms in the brain's venous sinuses. The clot prevents blood from draining out of the brain. As a result, blood cells may break and leak blood into the brain tissues, forming a hemorrhage. This chain of events is part of a stroke that can occur in adults and children of all ages.

A subarachnoid hemorrhage means that there is bleeding in the space that surrounds the brain. Most often, it occurs when a weakened area in a blood vessel (aneurysm) on the surface of the brain bursts and leaks. The blood then builds up around the brain and inside the skull increasing pressure on the brain. This can cause brain cell damage, life-long complications, and disabilities.