Brain Injury Glossary of Terms

Acceleration: An increase in rate or speed. Often associated with head injuries in vehicle collisions, as the brain hits the inside of the skull.

Alopecia: The loss or absence of hair; also referred to as "baldness".

Amnesia: Partial or total memory loss.

Angiogram: An X-ray test used to take images of the arteries or veins in the head, arms, legs, chest, back, or abdomen. Special dye is injected into a blood vessel with a thin tube to create clear images. Also referred to as an "arteriogram" for arteries or "venogram" for veins.

Anosmia: Partial or total loss of the sense of smell.

Anoxia: Absence of oxygen supply to an organ or a tissue; also referred to as “oxygen starvation”.

Anoxic Brain Injury: Occurs when the brain is completely deprived of oxygen, damaging the brain cells.

Apraxia: The inability to execute complex, purposeful movements despite being physically able and willing to do so.

Ataxia: The loss of muscle coordination and full control of bodily movements. May affect speech, eye movements, fingers, limbs, or the body.

Axons: The long, threadlike part of a nerve cell that passes electrical impulses away from the cell body and along to other cells. Axons are essential to nervous system functioning. Also referred to as “nerve fibers”.

Basal Ganglia: Structures in the base of the brain that are involved with coordinating voluntary movements.

Bipolar Disorder: A mental health disorder causing extreme mood and energy shifts, from elation to depression. Also referred to as “manic-depressive illness”.

Blast Injuries: A complex physical trauma injury resulting from exposure to an explosion. The explosion produces an overpressure blast wave that injures or ruptures organs surrounded by fluid or filled with air. This may include the brain, the lungs, the ear, or the gastrointestinal tract.

Brain: The coordinating center of the central nervous system. It regulates all sensation, intellectual ability, and nervous system activity.

Brain Stem: The portion of the brain that connects to the spinal cord. It controls the flow of messages between the brain and the body, as well as the basic bodily functions necessary for survival.

Cerebellum: Located at the back of the skull, it coordinates and regulates muscular activity.

Cerebral Hypoxia: Occurs when the brain receives inadequate oxygen supply. Symptoms include confusion and fainting. When mild or moderate, it is also referred to as “diffuse cerebral hypoxia”.

Cerebral Spinal Fluid: A clear bodily fluid in the brain and spine which acts as a cushion to provide basic protection for the brain. It is also involved in the autoregulation of cerebral blood flow.

Cerebrum: Located in the front of the skull, the cerebrum is the largest part of the brain. It is divided into the left and right hemispheres, which together are responsible for motor and sensory function, thought, memory, reason, and emotion.

Chronic Subdural Hematoma: A slow hemorrhage in the brain resulting from previous (often minor) head trauma that creates an old blood clot on the brain’s surface near its outer covering. May cause symptoms similar to other brain disorders and injuries.

Closed Head Injury: A type of traumatic brain injury where the skull and dura mater remain intact. Primarily caused by vehicle accidents, falls, assault, and sports-related injuries. Severity ranges from mild concussion to fatal.

Coma: An unconscious state that lasts for a prolonged or indefinite period.

Computerized Axial Tomography, or CT or CAT Scan: Using X-rays, multiple cross-sectional images are taken of the inside of the body to get clear, comprehensive images. Computers can combine the data to show a 3D view.

Concussion: A type of traumatic brain injury where the brain experiences a temporary loss of normal functioning in response to a non-penetrating injury (such as a blow or shaking).

Consciousness: The state of being awake and aware of the surrounding environment.

Contusion: An injury where the skin is not broken but the blood capillaries have been ruptured. Also referred to as a “bruise”. When related to brain injuries, it refers to bruised brain tissue.

Coup-Contrecoup: A brain injury occurring both at the site of impact and the opposite side of the brain. Often caused when a violent motion forces the head to suddenly stop, such as in a vehicle collision. Also referred to as an “acceleration-deceleration injury”.

Cranium: The skull.

Deceleration: A decrease in rate or speed. Often associated with head injuries in vehicle collisions, as the brain hits the inside of the skull.

Diffuse: Widely spread; not concentrated.

Diffuse Axonal Injury or DAI: A common and severe type of brain injury where damage of large nerve fibers covers a widespread area.

Diffuse Brain Injury: Injury to many areas of the brain rather than one specific location. Also referred to as “multifocal injuries”.

Diplopia: A disorder of vision in which a single object is seen in duplicate. Also referred to as “double vision”.

Dura Mater: Tough, fibrous membrane covering the brain and spinal cord. The outermost of the three layers surrounding the brain.

Dysarthria: A motor disorder producing difficult and unclear articulation of speech. Results from neurological injury of the motor-speech system. Symptoms can include laboured tongue movements, slow rate of speaking, abnormal voice quality, low volume, or drooling.

Dyskinesia: Impairment of voluntary movement, often manifesting in repetitive motions or lack of coordination. Usually experienced in the upper body.

Electroencephalograph, or EEG: A machine that measures electric activity in the brain through electrodes attached to the scalp.

Epidural Hematoma: A type of traumatic brain injury where blood builds up between the dura mater and the skull or spinal cord.

Euphoria: A state of intense happiness and well-being not justified by external reality.

Executive Functions: Refers to the effective management of cognitive processes, such as memory, reasoning, planning, problem solving, creativity, etc.

Expressive Aphasia: Communicative disorder causing difficulty using or understanding words. Symptoms often include being unable to find the correct words to express coherent thoughts, lack of spontaneous speech, labouring over words, and short and incomplete sentences. Results from injury to the language parts of the brain. Also referred to as “Broca’s aphasia”.

Focal Brain Injury: Injury to one localized area of the brain. Often results from injuries where the brain is struck by or strikes an object, or an injury where an object penetrates the skull.

Frontal Lobe: Found immediately behind the forehead, the frontal lobe coordinates certain higher cognitive functions such as problem solving, personality, selective attention, behaviour, learning, and movement.

Generalized Tonic-Clonic Seizures: A seizure or convulsion involving the entire body. Symptoms before the seizure may include sensory changes, hallucinations, or dizziness. Symptoms during the seizure may include rigid muscles, violent muscle contractions, and loss of consciousness. Also referred to as a “grand mal seizure”.

Glasgow Coma Scale (GCS): Neurological scale that attempts to objectively measure level of consciousness, often after a brain injury. Assessed based on ability to open eyes, verbal responsiveness, and motor responsiveness. Scores range from 3 to 15.

Glasgow Outcome Scale (GOS): Scale separating patients with traumatic brain injuries into five categories. Used to objectively grade the general functioning a brain injury’s severity based on trauma and mental ability. The scale predicts the long-term course of rehabilitation and ability to return to everyday life.

Hematoma: A swelling of clotted blood outside of a blood vessel. May cause significant swelling.

Herniation/Herniated: High pressure inside the skull causing compression of brain tissue. Can lead to death if not appropriately treated.

Hypertension: A medical term for abnormally high blood pressure.

Hypotension: A medical term for abnormally low blood pressure.

Hypoxia: Deficiency in oxygen reaching body tissues; e.g., brain tissues.

Intracranial Pressure (ICP) Monitor: A monitor placed inside the head to measure pressure within the skull. Used to determine the likelihood of complications due to pressure on the brain.

Impaired Initiation: Difficulty beginning an action.

Improvised Explosive Devices, or IEDs: A “homemade” explosive device constructed and used outside of conventional military action. Used to cause death or injury through an explosion or in combination with toxins. Can be produced in varying sizes, functioning methods, containers, and delivery methods.

Intracerebral Hematoma: A collection of blood inside the brain tissue.

Intracerebral Hemorrhage: Occurs when a blood vessel bursts in the brain, causing blood to leak into the brain. Can be caused by brain trauma.

Intracranial Pressure, or ICP: The amount of pressure inside the skull, brain, and cerebrospinal fluid. Normal pressure ranges from 5 to 15 mmHg. Levels over 20 mmHg are usually treated.

Limbic System: Group of nerves and structures in the brain that control basic emotions, instincts, and drives.

Lobes: Divide the brain into four sections: the frontal lobe, parietal lobe, occipital lobe, and temporal lobe. Each lobe is associated with different functions and spans both brain hemispheres.

Magnetic Resonance Imaging, or MRI: A test that creates detailed images of organs and soft tissues inside the body using a magnetic field and pulses of radio wave energy. Reveals different information than other imaging tests. In the brain, MRI can be used to find tumours, aneurysms, bleeding, nerve injury, etc.

Meninges: Three membranes enclosing the brain and spinal cord: dura mater, arachnoid, and pia mater. These membranes protect the brain and central nervous system.

Mild Traumatic Brain Injury, or mTBI: A brain injury involving the disruption of normal brain functioning due to trauma. Mild traumatic brain injury symptoms vary widely, depending on the area of the brain affected. Effects can last from a few hours to years. Classified on the Glasgow Coma Scale as 13-15. In some instances, is also referred to as a “concussion”.

Myalgia: Muscle pain.

Neurocognitive: Involving the central nervous system and cognitive abilities; e.g. relating to the ability to process thoughts, remember, etc.

Neurons: Functional unit of the nervous system consisting of a nucleus, cytoplasm, axon, and dendrites. Sends and receives information. Also referred to as a “nerve cell”.

Neuropsychology: The study of how brain function relates to and impacts behaviour, emotion, and cognition.

Neuroradiological Tests: Imaging tests for the brain using computers; includes CT scans, MRIs, angiograms, EEGs, SPECT scans, PET scans, and DTI scans.

Neurotransmitters: Chemicals in the brain released from a nerve cell that transmit an impulse from the nerve cell to another nerve, muscle, organ, or other tissue. Carries neurological information across gaps called synapses. Some neurotransmitters activate neurons, while others inhibit them.

Nystagmus: Involuntary, rapid, oscillating movement of the eyeballs.

Occipital Lobes: Found at the back of the brain, the occipital lobes process visual data and signals.

Ocular: Relating to the eye or vision.

Open Head Injury: An injury where the dura mater is broken and an object enters the brain (but does not exit it). Also referred to as a “penetrating head injury”.

Parietal Lobes: Found at the top of the head, the parietal lobes process movement, tactile sensations, and sensory information.

Penetrating Head Injury: An injury where the dura mater is broken and an object enters the brain. Also referred to as an “open head injury”.

Perseveration: Uncontrollable repetition of a particular response; e.g., a word, phrase or gesture. Involves the inability to change goals, tasks, or activities.

Photophobia: Abnormal, painful sensitivity to light.

Positron Emission Tomography, or PET Scan: Imaging test using a short-lived radioactive substance called a “tracer” to provide information about how a body’s organs and tissues are functioning. Reveals areas with higher levels of chemical activity and is helpful for evaluating neurological problems.

Post Deployment Health Assessment, or PDHA: Required for members of the United States military who are deployed outside of the continental United States for 30 days or more. Examines each service member for physical and behavioural health issues commonly associated with deployment.

Post Deployment Health Reassessment, or PDHRA: Required for members of the United States military 3 to 6 months after redeployment. Designed to address physical and psychological health concerns that may have emerged over time since deployment.

Post-Traumatic Stress Disorder, or PTSD: A condition of persistent mental and emotional stress after a traumatic injury or psychological shock. Symptoms typically include sleep disturbances, vivid flashbacks, and detachment from others.

Post-Traumatic Amnesia, or PTA: A state of confusion and memory loss following a brain injury or traumatic event.

Rancho Los Amigos Scale of Cognitive Functioning: Rehabilitation tool used to evaluate the recovery of a closed head injury patient, based on cognition and behaviour. Scored on a scale from 1 to 8. Often paired with the Glasgow Coma Scale.

Receptive Aphasia: Partial or total loss of ability to understand speech and written words. Difficulty interpreting sounds. Commonly manifests in speech that contains unnecessary or made-up words. Also referred to as “Wernicke’s aphasia”.

Seizure: Disruption of the brain’s normal electrical activity. Generalized seizures involve the entire brain, while partial seizures involve only one part of the brain. Symptoms often include uncontrollable movements or convulsions. There are over 20 different types of seizure disorders.

Shaken Baby Syndrome: A type of traumatic brain injury caused by violently shaking an infant or small child. Shaking causes the brain to hit the skull repeatedly, resulting in bruising, swelling, internal bleeding, permanent brain damage, or death.

Single-photon Emission Computed Tomography, or SPECT Scan: Imaging test that shows how blood is flowing through arteries and veins in the brain. May be more sensitive to brain injury than the MRI or CT scans.

Skull Fracture: Fracture or break in the skull.

Subdural Hematoma: Bleeding resulting in blood gathering between the dura mater and the brain. Also referred to as an “acute subdural hematoma”, in opposition to a chronic subdural hematoma. This is an emergency condition that requires immediate treatment.

Temporal Lobes: Found beneath the temples, the temporal lobes process memory, emotion, speech, visual perception, and auditory perception.

Thalamus: Found above the brainstem, the thalamus relays sensory and motor signals, processes pain, and regulates consciousness.

Tinnitus: Perception of sound in one or both ears, such as buzzing, ringing, or whistling, without external stimulus.

Traumatic Brain Injury, or TBI: Injury to the brain causing a disruption of normal function. Can result from rapid acceleration/deceleration, impact, or a penetrating brain injury. Classified in three levels of severity: Mild, Moderate, and Severe.

Whiplash: Neck injury caused by abrupt head movements forward and backward. Often associated with coup-contrecoup brain injuries.