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Glossary A-D

A-D   E-H   I-L   M-P   Q-Z

Absence Seizures – A non-convulsive generalized seizure when a person may appear to be staring into space with or without jerking or twitching movements of the eye muscles. These seizures may last for seconds, or even tens of seconds, with full recovery of consciousness and no confusion. People experiencing absence seizures sometimes move from one location to another without any purpose.

Abstract Thinking – Being able to apply abstract concepts to new situations and surroundings.

Acceleration – To increase speed and/or change velocity.

Alopecia – A condition of a loss of hair or baldness.

Amnesia – A loss of memory. Amnesia can be caused by brain injury, shock, fatigue, repression, illness and sometimes anesthesia.

Angiogram – A procedure in which a dye is injected through a thin tube into a blood vessel. Special x-ray pictures are taken, allowing your health care provider to view the blood vessels of the brain, heart or other part of the body. Also called an arteriogram for arteries or venogram for veins.

Anorexia – A loss of appetite, especially when prolonged over time.

Anosmia – The decrease or loss of the sense of smell.

Anoxia – Absence of oxygen supply to an organ.

Anoxic Brain Injury – Injury to the brain due to severe lack of oxygen. This usually happens when blood is unable to flow to the brain due to certain injuries,bleeding, or cardiac arrest.

Apraxia – The loss or impairment of the ability to perform complex coordinated movements despite having the desire and the physical ability to perform the movements.

Arthralgia – Joint pain or stiffness in a joint.

Ataxia – The inability to coordinate the movement of muscles. Ataxia may affect the fingers, hands, arms, legs, body, speech, or eye movements.

Axons – Also known as nerve fibers, an axon is a long, slender projection of a nerve cell, or neuron, that conducts electrical impulses away from the neuron's cell body or soma. Axons are the primary transmission lines of the nervous system.

Basal Ganglia – The deep brain structures that help start and control voluntary movements and postures.

Bipolar Disorder – Also known as manic-depressive illness, bipolar disorder is a brain disorder that causes unusual shifts in a person’s mood, energy, and ability to function.

Blast Injuries – Injuries that result from the complex pressure wave generated by an explosion. The explosion causes an instantaneous rise in pressure over atmospheric pressure that creates a blast over pressurization wave. Injuries to organs surrounded by fluid, such as the brain and air filled organs such as the ear, lung and gastrointestinal tract are common.

Brain – The main organ of the central nervous system (CNS). It is divided into the cerebrum, brainstem, and cerebellum. The brain regulates virtually all human activity.

Brain Stem – The lower extension of the brain where it connects to the spinal cord. Neurological functions located in the brainstem include those necessary for survival (breathing, heart rate) and for arousal (being awake and alert).

Cerebellum – The portion of the brain (located in the back) that helps coordinate movement.

Cerebral Hypoxia – The inadequate oxygen supply to brain tissue. Mild or moderate cerebral hypoxia is sometimes known as diffuse cerebral hypoxia. It can cause confusion and fainting, but its effects are usually reversible.

Cerebral Spinal Fluid – A colorless fluid that is found around and inside the brain and spinal cord, offering some protection and cushioning the brain.

Cerebrum – The largest part of the brain. It is divided into two hemispheres, or halves. It controls motor, sensory, and higher mental functions, such as thought, reason, emotion, and memory.

Chronic Subdural Hematoma – An "old" collection of blood and blood breakdown products between the surface of the brain and its outermost covering (the dura).

Closed Head Injury – Injury to structures within the skull or the brain that do not result in an opening in the, such as a direct blow to the head or a blast. Injuries may range from a mild concussion to potentially fatal.

Coma – A state of unconsciousness from which the person is not aware of the environment nor able to perform voluntary actions.

Computerized Axial Tomography, or CT or CAT Scan – A painless procedure in which x-rays are passed through the affected area at different angles, detected by a scanner, and analyzed by a computer. CT scan images show bones and blood collections more clearly than conventional x-rays. The computer can combine individual images to produce a three-dimensional view.

Concussion – A blow, jarring, shaking or other non-penetrating injury to the brain which causes a temporary decrease in normal brain activity.

Consciousness – The state of awareness of the self and the environment.

Contusion – A bruise. In terms of brain injury, a contusion refers to bruising of the brain tissues.

Coup-Contrecoup – An injury to the brain that occurs when an impact or violent motion brings the head to a sudden stop, causing injury to the impact site and the opposite side of the brain. This is also known as an acceleration / deceleration injury.

Cranium – Skull.

Deceleration – To reduce speed or go more slowly.

Diffuse – Widely spread.

Diffuse Axonal Injury, or DAI – Widespread injury of large nerve fibers (axons covered with myelin).

Diffuse Brain Injury – Injury to cells in many areas of the brain rather than in one specific location.

Diplopia – Seeing two images of a single object; double vision.

Dura Mater – The outermost of three membranes protecting the brain and spinal cord. It is tough and leather like.

Dysarthria – Difficulty in forming words or speaking them because of weakness of the muscles used in speaking. Tongue movements are usually labored and the rate of speaking may be very slow. Voice quality may be abnormal, usually excessively nasal; volume may be weak; drooling may occur.

Dyskinesia – Involuntary movements most often seen in the arms or legs.