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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.
To increase speed and/or change velocity.
A condition of a loss of hair or baldness.
A loss of memory. Amnesia can be caused by brain injury, shock, fatigue, repression, illness and sometimes anesthesia.
A procedure in which a dye is injected through a thin tube into a blood vessel. Special x-ray pictures are taken, allowing your healthcare 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.
A loss of appetite, especially when prolonged over time.
The decrease or loss of the sense of smell.
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.
A language disorder resulting from brain injury that can affect one or more of the following abilities: spoken language expression, spoken language comprehension, written expression, and reading comprehension. A person with expressive aphasia may struggle to find the right words to express their thoughts, omit small words, put words in the wrong order, or make up words. A person with receptive aphasia may have difficulty understanding what others tell them, find it hard to follow fast speech, misinterpret subtleties of language, or fail to understand complex grammar.
The loss or impairment of the ability to perform complex coordinated movements despite having the desire and the physical ability to perform the movements.
Joint pain or stiffness in a joint.
The inability to coordinate the movement of muscles. Ataxia may affect the fingers, hands, arms, legs, body, speech, or eye movements.
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.
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.
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).
The portion of the brain (located in the back) that helps coordinate movement. The cerebellum contributes to coordination, accuracy, and precision of body movements and is a major contributor to balance and equilibrium.
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.
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. In many cases, “cerebrum” may be used synonymously with "brain."
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 skull, such as a direct blow to the head or a blast. Injuries may range from a mild concussion to severe TBI.
A state of unconsciousness from which the person is not aware of the environment nor able to perform voluntary actions.
Computerized Axial Tomography (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 (Mild TBI)
A blow, jarring, shaking or other non-penetrating injury to the brain which causes a temporary disruption in normal brain activity.
The state of awareness of the self and the environment.
A bruise. In terms of brain injury, a contusion refers to bruising of the brain tissues.
A cause of 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.
A force described as a reduction of speed or to go more slowly.
Widely spread.
Diffuse Axonal Injury (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.
Seeing two images of a single object; double vision.
Dura Mater
The outermost of three membranes protecting the brain and spinal cord.
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.
Involuntary movements most often seen in the arms or legs.

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Electroencephalogram (EEG)
A test that measures electrical activity of the brain that is recorded from electrodes placed on the scalp.
Epidural Hematoma
Bleeding into the area between the skull and the dura mater.
An exaggerated or abnormal sense of well-being not based on reality.
Executive Functions
The ability to formulate and carry out plans effectively. These functions are essential for independent, creative and socially constructive behavior.
Focal Brain Injury
Damage confined to a small area of the brain. The focal damage is most often at the point where the head hits an object or where an object, such as a bullet, enters the brain.
Frontal Lobe
The front part of the brain; involved in planning, organizing, problem solving, selective attention, personality and a variety of "higher cognitive functions."
Generalized Tonic-Clonic Seizures
A seizure involving the entire body, previously known as a grand mal seizure. Such seizures usually involve muscle rigidity, violent muscle contractions, and alteration or loss of consciousness.
Glasgow Coma Scale
A scale used for measuring level of consciousness. Scoring is determined by three factors: eye opening ability, verbal responsiveness, and motor responsiveness. The scores range from 3 (lowest level of responsiveness) to 15 (highest level of responsiveness).
A collection of blood caused by the rupture or tearing of blood vessels.
Compression of brain tissue caused by high pressure inside the skull that can lead to death if not urgently medically treated.
The medical term for high blood pressure.
The medical term for low blood pressure.
Decreased oxygen levels in an organ, such as the brain.
Impaired Initiation
The diminished ability to take the first step in beginning an action.
Intracerebral Hematoma
Collection of blood inside the brain tissue.
Intracerebral Hemorrhage
A subtype of intracranial hemorrhage that occurs within the brain tissue itself. Intracerebral hemorrhage can be caused by brain trauma, or it can occur spontaneously in hemorrhagic stroke.
Intracranial Pressure (ICP)
The amount of pressure inside the skull resulting from the brain tissue, cerebrospinal fluid and blood volume. This pressure normally ranges from 0-10 mmHg.
Intracranial Pressure (ICP) Monitor
A monitoring device used to determine the pressure within the brain. It is used to assess potential complications resulting from increased pressure exerted on the brain.

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Limbic System
A group of structures deep within the brain that are associated with emotion and motivation.
A part of the brain located in each of the two hemispheres. Each hemisphere of the cerebrum is divided into four sections (or lobes) known as the frontal lobe, the parietal lobe, the occipital lobe, and the temporal lobe.
Magnetic Resonance Imaging (MRI)
A test that uses a powerful magnet linked to a computer to make detailed pictures of soft tissues inside the body.
The covering of the brain that consists of three layers: the dura mater, the arachnoid mater, and the pia mater. The primary function of the meninges and the cerebrospinal fluid is to protect the central nervous system (which includes the brain and spinal cord).
Mild Traumatic Brain Injury (Mild TBI, mTBI, Concussion)
Mild TBI involves a disruption of brain function caused by trauma. This disruption is characterized by, but not limited to, a loss of consciousness for less than thirty minutes, and post-traumatic amnesia lasting for less than 24 hours.
Military Acute Concussion Evaluation (MACE)
A standardized mental status exam that is used to evaluate concussion in theater. This screening tool was developed to evaluate a person with a suspected concussion.
Pain in one or more muscles.
Of, relating to, or involving the brain and the ability to think, remember or process thoughts.
A nerve cell that can receive and send information by way of connections with other nerve cells.
A science that combines the study of the brain’s structures and functions with psychological processes and human behaviors.
Neuroradiological Tests
Tests using computer-assisted brain scans. These tests allow providers to visualize the brain. Tests may include: CT Scan, MRI, Angiogram, EEG, SPECT Scan, PET Scan, DTI Scan.
Chemicals found within the brain that are released from a neuron which transmit signals from neuron to neuron across gaps called synapses. These chemicals either excite or inhibit specific reactions; an example is a motor neuron where the neurotransmitter causes contraction of muscles through stimulation of muscle fibers.
Involuntary, usually rapid movement of the eyes (side to side, up and down, or rotary) that can be caused by a head injury or stroke.
Occipital Lobe
The occipital lobes of the brain (cerebrum) are found at the back of the brain. These lobes receive signals from the eyes, process those signals, allow people to understand what they are seeing, and influence how people process colors and shapes.
Relating to the eye.
Open Head Injury
Trauma to the brain that occurs from a skull fracture or penetrating injury.

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Parietal Lobe
The part of the brain (cerebrum) that is involved with movement, and with the processing of signals received from other areas of the brain such as vision, hearing, motor, sensory and memory.
Penetrating Head Injury
A brain injury in which an object pierces the skull and enters the brain tissue.
The repeated and uncontrollable use of the same words or actions regardless of the situation.
An intolerance to light; or a painful sensitivity to strong light.
Positron Emission Tomography (PET Scan)
A specialized imaging technique that uses an injection of a short-lived radioactive substance and special CT scans. PET scanning provides information about the body's chemistry not available through other procedures. Unlike other imaging techniques that look at structures of the brain, PET looks at the energy use of different parts of the brain.
Post Deployment Health Assessment (PDHA)
The military’s global health screening that occurs when a unit or service member returns from an overseas deployment. The purpose of this screening is to review each service member's current health, mental health or psychosocial issues commonly associated with deployments, special medications taken during the deployment, possible deployment-related occupational/environmental exposures, and to identify deployment-related health concerns.
Post Deployment Health Reassessment (PDHRA)
A second assessment used three to six months following redeployment or return of service members from overseas deployment. PDHRA extends the continuum of care for deployment related heath concerns and provides education, screening, assessment and access to care.
Post-traumatic Stress Disorder (PTSD)
A condition where memories of traumatic events are re-lived after the fact.
Post-traumatic Amnesia (PTA)
The inability to remember things following a traumatic event. Memory loss caused by brain damage or severe emotional injury.
Rancho Los Amigos Levels of Cognitive Functioning
A scale used to follow the recovery of the TBI survivor and to determine when he or she is ready to begin a structured rehabilitation program.
Uncontrolled electrical activity in the brain, which may produce a physical convulsion, minor physical signs, thought disturbances, or a combination of symptoms. Seizures fall into two main groups. Focal seizures, also called partial seizures, happen in just one part of the brain. Generalized seizures are a result of abnormal activity throughout the brain.
Single-photon Emission Computed Tomography (SPECT Scan)
Test that uses the injection of a weak radioactive substance into a vein, followed by pictures taken with special cameras. This test is similar to a PET scan and provides information on the energy being used by the brain.
Skull Fracture
A break, split or crack in the skull.
Subdural Hematoma
Bleeding confined to the area between the outer-most covering of the brain (dura) and the brain.
Temporal Lobes
The temporal lobes of the brain (cerebrum) are located at about ear level, and are the main memory center of the brain, contributing to both long-term and short-term memories. The temporal lobe is also involved with understanding what is heard, and with the ability to speak. An area on the right side is involved in visual memory and helps people recogn