Hematoma: A collection of blood forming a definite swelling which compresses and damages the brain around it.
Head Injury/ Mild: Causes brief loss of consciousness for 15 minutes or less with a period of post-traumatic amnesia of less than 1 hour.
Head Injury/ Moderate: Defined as being a condition where the patient has been in a coma for 6 hours, and a period of post-traumatic amnesia of up to 24 hours.
Head Injury/ Severe: Defined as being a condition where the patient has been in a coma for 6 hours or more, or a post-traumatic amnesia of 24 hours or more.
Hematoma: Heavy bleeding into or around the brain caused by damage to a major blood vessel in the head.
Hemianopia: Blindness in the same side of both eyes which can follow damage to the brain. This can cause an inability to see things on the left or right side.
Hemispheres: The two halves of the brain which are divided down the middle and called the cerebrum.
Hemorrhagic Stroke: A stroke caused by bleeding out of one of the major arteries leading to the brain.
Hydrocephalus: Enlargement of the ventricles due to an increase of cerebrospinal fluid (CSF) on the brain.
Hypoxia: Decreased oxygen levels in an organ, such as the brain; less severe than anoxia.