Medical Dictionary

A

• Achondroplastic – A hereditary condition in which the growth of long bones by ossification of cartilage is retarded, resulting in very short limbs and sometimes a face that is small in relation to the (normal-sized) skull.
• Acute – Sharp, severe, having sudden onset, sharp rise and short course; lasting a short time; seriously demanding urgent attention.
• Acute Care – The phase of managing health problems which is conducted in a hospital on patients needing medical attention.
• Adiadochokinesia – Inability to stop one movement and follow it immediately with movement in the opposite direction.
• Afferent Neuron – a neuron conducting impulses inwards to the brain or spinal cord.
• Agnosia – Failure to recognize familiar objects although sensory mechanism is intact. May occur for any sensory modality.
• Agraphia – Inability to express thoughts in writing.
• Akinetic Mutism – A condition of silent, alert-appearing, immobility that characterizes certain subacute or chronic states of altered consciousness. Sleep-wake cycles have been retained, but no observable evidence for mental activity is evident; spontaneous motor activity is lacking; person appears to be aware but inactive. Exhibited by persons with high brain stem lesions.
• Alexia – Inability to read.
• Allograft – A tissue graft from a donor genetically unrelated to the recipient.
• Amyotrophic Lateral Sclerosis – (ALS, motor neuron disease, Lou Gehrigs disease). A degenerative disorder affecting the motor neuron cells and the motor tracts in the brain and spinal cord.
• Analgesia – The absence of pain.
• Anasthesia – Loss of bodily sensation with or without loss of consciousness.
• Anasthesia, Block – Anesthesia of an area supplied by a nerve; produced by an anesthetic agent applied to the nerve.
• Anasthesia, Local – Loss of sensation in a small area of the body.
• Aneurysm – A balloon-like deformity in the wall of a blood vessel. The wall weakens as the balloon grows larger, and may eventually burst, causing a hemorrhage.
• Angiogram – An invasive diagnostic test that uses a special dye injected into the arteries by a catheter to visualize the blood vessels.
• Anterior Cervical Discectomy and Fusion (ACDF) – a common surgical procedure to treat nerve root or spinal cord compression by decompressing the spinal cord and nerve roots of the cervical spine in order to stabilize the corresponding vertebrae.
• Anticoagulant – A substance that prevents coagulation; that is, it stops blood from clotting.
• Aphasia – Loss of the ability to express oneself and/or to understand language. Caused by damage to brain cells rather than deficits in speech or hearing organs.
• Aphemia – The isolated loss of the ability to articulate words without loss of the ability to write or comprehend spoken language.
• Apraxia – Inability to carry out a complex or skilled movement; not due to paralysis, sensory changes, or deficiencies in understanding.
• Arachnoid Mater – A layer of the meninges, membranes that contain the central nervous system.
• Arteries – The blood vessels that carry the oxygenated blood to the organs.
• Arteriovenous Malformation (AVM) – A “tangle” of blood vessels present from birth which may be prone to bleeding.
• Atherosclerosis – Thickening of the arterial wall of blood vessels due to deposition of lipids (fats) and blood clots.
• Arthrodesis (also known as Artificial Ankylosis or Syndesis) – The artificial induction of joint ossification between two bones via surgery. This is done to relieve intractable pain in a joint which cannot be managed by pain medication, splints, or other normally-indicated treatments.
• Arthralgia – Joint pain.
• Arthritis – A group of conditions involving damage to the joints of the body.
• Arthroplasty – Surgical reconstruction or replacement of a malformed or degenerated joint.
• Aspiration – When fluid or food enters the lungs through the wind pipe. Can cause a lung infection or pneumonia.
• Ataxia – A problem of muscle coordination not due to apraxia, weakness, rigidity, spasticity or sensory loss. Caused by lesion of the cerebellum or basal ganglia. Can interfere with a person’s ability to walk, talk, eat, and to perform other self care tasks.
• Atrial Fibrillation – An abnormal rhythm of the heart that can result in an increased risk of stroke due to the formation of emboli (blood clots) in the heart.
• Atrophy – A wasting away or decrease in size of a cell, tissue, organ, or part of the body caused by lack of nourishment, inactivity or loss of nerve supply.
• Avascular – Without blood vessels.
• Autoimmune – An abnormal response of the immune system, causing antibodies and immune mediated cells to attack parts of the body. This mechanism may explain many diseases.
• Axis – The second cervical vertebra on which the head turns.
• Axon – The inner core of peripheral nerves.

B

• Back Ache – An ache localized in the back.
• Backbone – The vertebrate spine or spinal column.
• BAER (Brainstem Auditory Evoked Response) – Measures function of Central Nervous System, including pathway from brainstem.
• Basal Ganglia – A series of structures located deep in the brain responsible for motor movements.
• Benign – Of no danger to health; not recurrent or progressive; not malignant.
• Bilateral – Pertaining to both right and left sides.
• Biopsy – Tissue from a living body to determine the cause or extent of a disease.
• BMP – Bone morphogenic protein.
• Bone – The dense, semirigid, porous, calcified connective tissue forming the major portion of the skeleton of most vertebrates.
• Bone graft – A piece of bone used to take the place of a removed bone or bony defect.
• Bone plate – A sheet of metal or titanium, used in conjunction with bone screws for the fixation of bone.
• Bone screws – Screws used to immobilize, for bone fixation or plate fixation.
• Bradykinesia – The slowing of motor movements due to dysfunction of the basal ganglia and related structures.
• Brain Scan – A scintigram of the brain, used to identify cerebral blood flow and to detect intracranial masses, lesions, tumors, or infarcts.
• Brain Stem – The part of the brain continuous with the spinal cord and comprising the medulla oblongata and pons and midbrain and parts of the hypothalamus.

C

• Carotid Artery – Either of two major arteries of the neck and head; branches from the aorta
• Cartilage – A tough, elastic, fibrous connective tissue found in various parts of the body, such as the joints, outer ear, and larynx. A major constituent of the embryonic and young vertebrate skeleton, it is converted largely to bone with maturation.
• CAT Scan (Computerized Axial Tomography) – A specialized X-ray examination that is often used to visualize the brain and spinal structures.
• Catheter – A flexible tube for withdrawing fluids from, or introducing fluids into, a cavity of the body. Frequently used to drain the urinary bladder (Foley catheter).
• Cataplexy – A sudden loss of muscle tone and strength, usually caused by an intense emotional stimulus.
• Central Nervous System – Refers to the brain and the spinal cord.
• Centrum – The main body of a vertebrae.
• Cerebellum – The portion of the brain (located at the back) which helps coordinate movement. Damage may result in ataxia.
• Cerebral Aneurysm – A defect that results in weakness in the wall of a blood vessel that can lead to bleeding in the brain.
• Cerebrovascular Disease – Disorders that affect the blood vessels that supply the brain that may result in a stroke.
• Cerebral Angiography – The brain substance is pushed aside and compressed by the presence of a brain tumor, aneurysm, swelling or hematoma.
• Cerebral Compression – The brain substance is pushed aside and compressed by the presence of a brain tumor, aneurysm, swelling or hematoma.
• Cerebral Decompression – Relief of intracranial pressure by removal of a skull flap and incision of the dura mater.
• Cerebral Infarct – When the blood supply is reduced below a critical level to a specific region of the brain and the brain tissue in that region dies.
• Cerebral Spinal Fluid (CSF) – Liquid which fills the ventricles of the brain and surrounds the brain and spinal cord.
• Cerebrospinal Fluid – The fluid that surrounds the brain and the spinal cord.
• Cervical – Relating to the neck or cervix.
• Cercical Collar – A supportive garment that encircles the neck following an injury or surgery to the cervical region.
• Cervical Plexus – A nerve plexus lying beneath the sternocleidomastoid muscle.
• Cervical Fusion – Where a determinate number of cervical vertebrae are fixated using bone screws, cages and bone plates.
• Clonus – A form of movement marked by contractions and relaxations of a muscle, occurring in rapid succession, after forcible extension or flexion of a part.
• Coagulation – A complex process by which blood forms clots.
• Coccyx – The final segment of the ape vertebral column.
• Chronic – Marked by long duration or frequent recurrence.
• Collagen – The main supportive protein of cartilage, connective tissue, tendon, skin, and bone.
• Coma – A state of unconsciousness from which the patient cannot be awakened or aroused, even by powerful stimulation; lack of any response to one’s environment.
• Concussion – The common result of a blow to the head or sudden deceleration usually causing an altered mental state, either temporary or prolonged. Physiologic and/or anatomic disruption of connections between some nerve cells in the brain may occur. Often used by the public to refer to a brief loss of consciousness.
• Contracture – Loss of range of motion in a joint due to abnormal shortening of soft tissues.
• Contralateral – Opposite side.
• Contrecoup – Bruising of the brain tissue on the side opposite where the blow was struck.
• Corticospinal Tract – The nervous system structures that begin in the brain and travel to the motor neuron cell to innervate the motor nerves.
• Coup Damage – Damage to the brain at the point of impact.
• CT Scan/Computerized Axial Tomography – A series of X-rays taken at different levels of the brain that allows the direct visualization of the skull and intracranial structures. A scan is often taken soon after the injury to help decide if surgery is needed. The scan may be repeated later to see how the brain is recovering.
• Cytology – The study of cells, their origin, structure, function, and pathology.

D

• Decerebrate Posture (Decerebrate Rigidity) – Exaggerated posture of extension as a result of a lesion to the prepontine area of the brain stem, and is rarely seen fully developed in humans. In reporting, it is preferable to describe the posture seen.
• Decompression – The relief of pressure on a body part by surgery.
• Deep Vein Thrombosis (DVT) – A blood clot in a vein, located deep from the skin, most commonly.
• Diaschisis – A theoretical state following brain injury in which healthy areas connected to the damaged area show a temporary loss of function.
• Degenerative Disc Disease – Degeneration of the intervertebral disc of the spine.
• Dementia – An acquired loss of cognitive function that may affect language, attention, memory, personality and abstract reasoning.
• Demyelinating – An inflammatory process that disrupts the myelin coating of nervous system structures.
• Diffuse Axonal Injury (DAI) – A shearing injury of large nerve fibers (axons covered with myelin) in many areas of the brain. It appears to be one of the two primary lesions of brain injury, the other being stretching or shearing of blood vessels from the same forces, producing hemorrhage.
• Diffuse Brain Injury – Injury to cells in many areas of the brain rather than in one specific location.
• Diplegia – Paralysis of corresponding parts on both sides of the body, such as both arms.
• Diplopia – Seeing two images of a single object; double vision.
• Discitis – An infection in the intervertebral disc space.
• Discogram – An x-ray image produced by discography.
• Diskography – Radiography of the vertebral column after injection of radiopaque material into an intervertebral disk.
• Dysesthesia – Unpleasant, abnormal sense of touch, and it may be, or not be, considered as a kind of pain.
• Dysplasia – Refers to an abnormality of development.

E

• Echocardiogram – A diagnostic test to detect abnormalities of the heart using an ultrasound probe to image the cardiac structures.
• Edema – Collection of fluid in the tissue causing swelling.
• Electroencephalogram (EEG) – A record of the tiny electrical impulses produced by the brain’s activity. By measuring characteristic wave patterns, the EEG can help diagnose certain conditions of the brain.
• Electrocardiogram (ECG/EKG) – The recording made by electrode pads located on the patient’s chest to monitor heart rate and rhythm. These are connected to a monitor and used routinely in the intensive care unit.
• Electroencephalogram (EEG) – A procedure that uses electrodes on the scalp to record electrical activity of the brain. Used for detection of epilepsy, coma and brain death.
• Electromyography (EMG) – An insertion of needle electrodes into muscles to study the electrical activity of muscle and nerve fibers. It may be somewhat painful to the patient. Helps diagnose damage to nerves or muscles.
• Embolism – The sudden blocking of an artery or a vein by a blood clot, bubble of air, deposit of oil or fat, or small mass of cells deposited by the blood flow.
• Encephalography – Non-invasive use of ultrasound waves to record echoes from brain tissue. Used to detect hematoma, tumor, or ventricle problems.
• Encephalitis – Inflammation or infection involving the brain.
• Endotracheal Tube – A tube that serves as an artificial airway and is inserted through the patient’s mouth or nose. It passes through the throat and into the air passages to help breathing. To do this it must also pass through the patient’s vocal cords. The patient will be unable to speak as long as the endotracheal tube is in place. It is this tube that connects the respirator to the patient.
• Epidural – An injection into the epidural space of the spine.
• Epidural – Outside the brain and its fibrous covering, the dura, but under the skull.
• Esophagus – The portion of the digestive canal between the pharynx and stomach, consisting of a cervical part from the cricoid cartilage to the thoracic inlet, a thoracic part from the thoracic inlet to the diaphragm, and an abdominal part below the diaphragm to the stomach.
• Equilibrium – Normal balance reactions and postures.
• Excision – Surgical removal by cutting, as of a tumor or a portion of a structure or organ.

F

• Fibrosis – Formation of fibrous tissue.
• Frontal Lobe – Front part of the brain; involved in planning, organizing, problem solving, selective attention, personality and a variety of “higher cognitive functions.”
• Foramen – A natural opening or passage, especially one into or through a bone.
• Foraminotomy – A medical operation used to relieve pressure on nerves that are being compressed by the intervertebral foramina, the passages through the bones of the vertebrae of the spine that pass nerve bundles to the body from the spinal cord.
• Fasciculation – A localized uncoordinated, uncontrollable twitching of a single muscle group innervated by a single motor nerve fiber or filament that may be palpated and seen under the skin.
• Fracture – A break or rupture in a bone.

G

• GCS (Glasgow Coma Scale) – A neurological scale that aims to give a reliable, objective way of recording the conscious state of a person for initial as well as subsequent assessment. A patient is assessed against the criteria of the scale, and the resulting points give a patient score between 3 (indicating deep unconsciousness) and either 14 (original scale) or 15 (the more widely used modified or revised scale).
• Gadolinium – A contrast agent that is given intravenously during MRI (magnetic resonance imaging) to increase visualization of specific abnormalities.
• Graft – Any tissue or bone for implantation or transplantation.

H

• Hemangioma – A benign tumour consisting of a mass of blood cells.
• Hematoma – The collection of blood in tissues or space following rupture of a blood vessel.
• Hematomyelia – Hemorrhage into the substance of the spinal cord, usually caused by trauma.
• Hemiplegia – Paralysis of one side of the body as a result of injury to neurons carrying signals to muscles from the motor areas of the brain.
• Hemiparesis – Weakness of one side of the body.
• Hemorrhage – Bleeding that occurs following damage to blood vessels. Bleeding may occur within the brain when blood vessels in the brain are damaged. (See Hematoma).
• Hematorrhachis – Hemorrhage into the vertebral canal.
• Herniation – A protrusion of a body organ or portion of an organ through an abnormal opening in a membrane, muscle, or other tissue.
• Hydrocephalus – Enlargement of fluid-filled cavities in the brain, not due to brain atrophy.
• Hyperextension – Movement at a joint to a position beyond the joint’s normal maximum extension.
• Hyperflexion – Flexion of a limb or part beyond its normal range.
• Hyperthermia – A much higher than normal body temperature induced therapeutically or iatrogenically.
• Hyperlordosis – Increase in the normal anterior curve of the cervical and lumbar spine.
• Hypothermia – Decrease in body temperature beyond normal limits.
• Hypoxia – A potentially fatal condition, occurs when body temperature falls below 95°F (35°C).
• Hypoxemia – An abnormally low level of oxygen in the blood. When a patient’s arterial blood sample is measured and a low level of oxygen is noted it is more appropriate to refer to hypoxemia rather than hypoxia.
• Hyperesthesia – An abnormal or pathological increase in sensitivity to sensory stimuli, as of the skin to touch or the ear to sound.

I

• Inferior – Situated below, or directed downward.
• Instrumentation – The use of instruments during surgery.
• Intercerebral – Between the cerebral hemispheres.
• Intracranial Pressure (ICP) – Cerebrospinal fluid (CSF) pressure measured from a needle or bolt introduced into the CSF space surrounding the brain. It reflects the pressure inside of the skull.
• Intracranial Pressure Monitor – An ICP monitor. A monitoring device to determine the pressure within the brain. It consists of a small tube (catheter) attached to the patient at the skull by either a ventriculostomy, subarachnoid bolt, or screw and is then connected to a transducer, which registers the pressure.
• Intracranial Insult – Something that causes injury to the brain. Includes hematomas (intraparenchymal and extraparenchymal; immediate or delayed) elevations of intracranial pressure (ICP), brain swelling, edema and vasospasm.
• Intravenous (IV) – Tubing inserted into a vein through which fluid and medications can be given.
• Ipsilateral – Same side of the body.
• Ischemia – A severe reduction in the supply of blood to body tissues.
• Isthmic – Relating to an anatomical isthmus.

J

• Joint – The point where bones meet.

K

• Kinetic – Pertaining to or producing motion.
• Kyphosis – The upper back bone (thoracic region), is normally curved forward. If the curve exceeds 50° it is considered abnormal (kyphotic). Kyphosis is the extreme curvature of the upper back also known as a “hunchback”.
• Laminectomy – Excision of a vertebral lamina.
• Lateral – Denoting a position farther from the median plane or midline of the body or a structure.
• Ligament – A band of fibrous tissue connecting bones or cartilages, serving to support and strengthen joints.

L

• Lipoma – A benign tumor composed chiefly of fat cells.
• Lordoscoliosis – A combination of lordosis and scoliosis.
• Lordosis – The anterior concavity in the curvature of the lumbar and cervical spine as viewed from the side.
• Lumbago – A painful condition of the lower back, as one resulting from muscle strain or a slipped disk.
• Lumbar – Of, near, or situated in the part of the back and sides between the lowest ribs and the pelvis.
• Lumbar Puncture – (also known as a Spinal Tap) A procedure that involves removing some of the cerebrospinal fluid from the base of the spine. The physician will first use a local anesthetic on the skin and soft tissues in the lower back. Cerebrospinal fluid is obtained from the spinal area using a small needle and a syringe.
• Lacunar – A subtype of stroke that affects the deeper parts of the brain and involves the tiny perforating arteries.
• Lyme Disease – A disease that affects the joints, nervous system and heart that is transmitted by the deer tick, and is caused by a parasite known as a Borrelia.

M

• Malignant – Usually refers to tumors that are cancerous; may refer to a disease state that has a debilitating unremitting course.
• Meningitis – Inflammation or infection of the meninges, which are the coverings of the brain.
• Metastatic – Usually used to describe cancerous lesions that spread to other organs in the body.
• Migraine – A headache syndrome characterized by throbbing, usually one sided pain, that may be associated with nausea, vomiting and visual disturbances.
• Monoplegia – Paralysis of one arm or one leg.
• Motor Neuron Cells – The cells located in the spinal cord that give rise to the nerves that supply the muscles.
• MRI (Magnetic Resonance Imaging) – A noninvasive nuclear procedure for imaging tissues of high fat and water content that cannot be seen with other radiologic techniques. The MRI image gives information about the chemical makeup of tissues, thus making it possible to distinguish normal, cancerous, atherosclerotic, and traumatized tissue masses in the image.
• Multi-Infarct Dementia – A dementia that is caused by the cumulative affect of having had many strokes in the brain.
• Muscular Dystrophy – A congenital (hereditary) disorder of the muscles resulting in weakness and dysfunction of the muscles.
• Myasthenia Gravis – An autoimmune disease that causes muscle weakness.
• Myelin – The outer lipid rich (fatty) layer that covers nerves and nervous system pathways in the brain and spinal cord.
• Myelography – A medical test involving injection of dye into the spinal subarachnoid space so that an x-ray of the spinal cord can be taken. Used to detect spinal cord tumors, anatomical defects and disc problems.
• Myopathy – A disease resulting in dysfunction of the muscles usually causing weakness and atrophy.

N

• Narcolepsy – A disorder marked by excessive daytime sleepiness, uncontrollable sleep attacks, and cataplexy (a sudden loss of muscle tone, usually lasting up to half an hour).
• Nerve – A cordlike structure comprising a collection of nerve fibers that convey impulses between a part of the central nervous system and some other body region.
• Neural Arch – The primordium of the vertebral arch; one of the cartilaginous structures surrounding the embryonic spinal cord.
• Neuralgia – Neuralgia is defined as an intense burning or stabbing pain caused by irritation of or damage to a nerve.
• Neurectomy – Surgical removal of a nerve or part of a nerve.
• Neuritis – The inflammation of a nerve or group of nerves that is characterized by pain, loss of reflexes, and atrophy of the affected muscles.
• Neurolysis – The surgical freeing of a nerve from inflammatory adhesions.
• Neuroma – A tumor growing from a nerve or made up largely of nerve cells and nerve fibers.
• Neurons – The nerve cells of the brain that carry out neurological function.
• Neuropathy – A functional disturbance or pathological change in the peripheral nervous system.
• Neurosurgeon – A physician who specializes in surgery of the nervous system and its surrounding structures. Neurosurgeons operate on the brain, skull, scalp and spinal column.
• Neuro surgery – A surgical speciality that is involved with the treatment of brain, spinal cord and peripheral nerve disorders.
• NPH (Normal Pressure Hydrocephalus) – Increase in pressure within the ventricles of the brain, causing dementia, gait difficulties and urinary incontinence.
• Nystagmus – The jerking “to and fro” movement of the eyes that occurs when disorders affect the control of eye movement

O

• Occipital Lobe – Region in the back of the brain which processes visual information. Damage to this lobe can cause visual deficits.
• Occiput – The back part of the head or skull.
• Olisthy – The slippage of a bone from its normal anatomic site, as in a slipped disk.
• Orthopedics – The branch of medicine devoted to the study and treatment of the skeletal system, its joints, muscles and associated structures.
• Orthosis – Splint or brace designed to improve function or provide stability.
• Ossification – Formation of or conversion into bone or a bony substance.
• Osteomyelitis – A bone infection.
• Osteophyte – A small abnormal bony outgrowth.
• Osteoporosis – Literally means “porous bones.” It occurs when bones lose an excessive amount of their protein and mineral content, particularly calcium. Over time, bone mass, and therefore bone strength, is decreased. As a result, bones become fragile and break easily.
• Oximeter – A device to monitor the patient’s oxygen saturation levels to assist in the prevention of hypoxia.

P

• Paraneoplastic – Disorders that occur due to the remote effects of cancer, such as through the mechanism of hormonal or antibody production.
• Paresthesias – Unusual sensory symptoms of tingling, numbness or other abnormal feelings of sensation.
• Paraplegia – Complete paralysis of the lower half of the body including both legs, usually caused by damage to the spinal cord.
• Parietal Lobe – One of the two parietal lobes of the brain located behind the frontal lobe at the top of the brain.
• Parietal Lobe, Right – Damage to this area can cause visuo-spatial deficits (e.g., the patient may have difficulty finding their way around new, or even familiar, places).
• Parietal Lobe, Left – Damage to this area may disrupt a patient’s ability to understand spoken and/or written language.
• Peripheral Nervous System – Refers to the nerves and muscular structures.
• Perceptual-Motor – Interaction of the perceptual abilities with motor abilities.
• Phlebitis – Inflammation of a vein.
• Plasticity – The ability of cellular or tissue structures and their resultant function to be influenced by an ongoing activity.
• Platysma – A platelike muscle that originates from the fascia of the cervical region and inserts in the mandible and the skin around the mouth. It wrinkles the skin of the neck and depresses the jaw.
• Plaque – The lesion that occurs in the “white matter” of the brain due to demyelination.
• Plexus – A network or tangle, chiefly of vessels or nerves.
• Posterior – Directed toward or situated at the back.
• Prosthesis – An artificial replacement for a missing body part, such as an artificial limb or total joint replacement.
• Proximal – Nearer to a point of reference such as an origin, a point of attachment, or the midline of the body.
• Pseudoarthrosis – A pathological entity characterized by a nonosseous union of bone fragments of a fractured bone due to inadequate immobilization leading to existence of the ‘false joint’ that gives the condition its name.
• Ptosis – Drooping of a body part, such as the upper eyelid, from paralysis, or drooping of visceral organs from weakness of the abdominal muscles.

Q

• Quadriparesis – Weakness of all four limbs.
• Quadriplegia – Paralysis of all four limbs (from the neck down). British authors often use the prefix “tetra” to mean four, so they may describe a patient as having tetraplegia.

R

• Rachialgia – Pain in the vertebral column.
• Rachicentisis (Lumbar Puncture) – A procedure in which the doctor inserts a small needle into the spinal cavity in the lower back to withdraw some spinal fluid for testing. Also known as a “spinal tap.”
• Rachiocampsis – Spinal curvature.
• Rachiopathy – A disease involving a spinal nerve root.
• Radiculopathy – Disease of the spinal nerve roots.
• Rachiodynia – Pain in the vertebral column.
• Radiculopathy – Irritation and inflammation of one of the nerve roots in the vicinity of the spinal column.
• REM: (Rapid Eye-Movement Sleep) – The stage of sleep that is characterized by decreased muscle tone, rapid eye movements and dreaming.
• Radiologist – A medical doctor specially trained in radiology (x ray) interpretation and its use in the diagnosis of diseases and injuries.
• ROM (Range of Motion) – Refers to movement of a joint (important to prevent contractures).
• Range of Motion, Active – The muscles around the joint do the work to move it.
• Range of Motion, Passive – Movement of a joint by means other than contraction of the muscles around that joint; e.g., someone else moves the joint.
• Reflex – A reflected action or movement; the sum total of any particular automatic response mediated by the nervous system.
• Retrolisthesis – Backward slippage of one vertebra onto the vertebra immediately below.
• Rhizolysis – Radiofrequency neurotomy; interruption of spinal nerve roots by coagulation with radiofrequency waves.
• Rigidity – Stiffness in the limbs or body due to dysfunction of the basal ganglia and related structures.

S

• Sacral – Pertaining to the sacrum.
• Sacrum – The triangle-shaped bone located between the fifth lumbar vertebra and the coccyx that consists of five vertebrae fused together. The sacrum joins on each side with the bones of the pelvis.
• Sagittal – Pertaining to a suture or an imaginary line extending from the front to the back in the midline of the body or a part of the body, dividing into right and left parts.
• Sciatica – Pain or discomfort associated with the sciatic nerve. This nerve runs from the lower part of the spinal cord, down the back of the leg, to the foot. Injury to or pressure on the sciatic nerve can cause the characteristic pain of sciatica: a sharp or burning pain that radiates from the lower back or hip, possibly following the path of the sciatic nerve to the foot.
• Sciatic Nerve – A large nerve in the lumbar-sacral spine region that is composed of multiple nerve roots that supply the lower extremities
• Scoliosis – A side-to-side curvature of the spine.
• Seizure – The abnormal electrical discharge of brain cells (neurons) that results in a transient disturbance in brain function.
• SEP (Somatosensory Evoked Response) – Measures function of Central Nervous System, including pathway from the extremities.
• Serotonin – An important neurotransmitter (communicates information chemically between brain cells) that is involved in the pain disorders and emotional perceptions.
• Shunt – A procedure to draw off excessive fluid in the brain. A surgically-placed tube running from the ventricles which deposits fluid into either the abdominal cavity, heart or large veins of the neck.
• Sleep Apnea – A disorder that results in apnea (cessation of breathing) during sleep often due to obstruction of the upper airway.
• Spasm – An involuntary and abnormal muscular contraction; also, a sudden violent and temporary effort or emotion.
• Spasticity – An involuntary increase in muscle tone (tension) that occurs following injury to the brain or spinal cord, causing the muscles to resist being moved. Characteristics may include increase in deep tendon reflexes, resistance to passive stretch, clasp knife phenomenon, and clonus.
• Spatial Ability – Ability to perceive the construction of an object in both two and three dimensions. Spatial ability has four components: the ability to perceive a static figure in different positions, the ability to interpret and duplicate the movements between various parts of a figure, the ability to perceive the relationship between an object and a person’s own body sphere, and the ability to interpret the person’s body as an object in space.
• Spinal Canal – The opening that runs through the center of the column of spinal bones (vertebrae), and through which the spinal cord passes.
• Spinal Cord - The thick, whitish cord of nerve tissue that extends from the medulla oblongata down through the spinal column and from which the spinal nerves branch off to various parts of the body.
• Spinal Fusion – A surgical procedure in which vertebrae are joined.
• Spinal Stenosis – Spinal stenosis is any narrowing of the spinal canal that causes compression of the spinal nerve cord.
• Spinal Column – The series of articulated vertebrae, separated by intervertebral disks and held together by muscles and tendons, that extends from the cranium to the coccyx, encasing the spinal cord and forming the supporting axis of the body.
• Spondylarthritis – Arthritis of the spine.
• Spondylitis – inflammation of vertebrae.
• Spondylolisthesis – Forward displacement of one of the lower lumbar vertebrae over the vertebra below it or over the sacrum.
• Spondylolysis – A degenerative disease of the spinal column, especially one leading to fusion and immobilization of the vertebral bones.
• Spondylopathy – Disease of the vertebrae or of the spinal column.
• Spondylosis – A degenerative disease of the spinal column, especially one leading to fusion and immobilization of the vertebral bones.
• Stenosis – A constriction or narrowing of a duct or passage; a stricture.
• Strabismus, External – Outward turning of the eye which may be due to a lesion of the oculomotor nerve (III) causing paralysis of the medial rectus muscle.
• Strabismus, Internal – Inward turning of the eye which may be due to a lesion of the abducens nerve (VI) causing paralysis of the lateral rectus muscle.
• Status Epilepticus – Seizures that continue for more than twenty minutes without an intervening period of responsiveness.
• Subarachnoid Hemorrhage – Bleeding in the area surrounding the brain, that is usually a result of the rupturing of a cerebral aneurysm in the brain.
• Subarachnoid Screw – Also Subarachnoid Bolt. A device for measuring intracranial pressure which is screwed through a hole in the skull and rests on the surface of the brain.
• Subdural – Beneath the dura (tough membrane) covering the brain and spinal cord.

T

• Temporal Lobes – There are two temporal lobes, one on each side of the brain located at about the level of the ears. These lobes allow a person to tell one smell from another and one sound from another. They also help in sorting new information and are believed to be responsible for short-term memory.

  Right Lobe – Mainly involved in visual memory (i.e., memory for pictures and faces).

  Left Lobe – Mainly involved in verbal memory (i.e., memory for words and names).

• Tendon – A fibrous cord of connective tissue continuous with the fibers of a muscle and attaching the muscle to bone or cartilage.
• Tensilon Test – A diagnostic test that is used to confirm the disease Myasthenia Gravis. A substance that interferes with the breakdown of acetycholine is injected intravenously, and the response is monitored.
• Thrombus – Blood clot.
• TIA (Transient Ischemic Attack) – Neurological symptoms occur due to transient interruption of the blood flow to the brain.
• Titanium – A strong, low-density, highly corrosion-resistant metallic element, used in ultraviolet sunscreens and as a surgical aid to repair fractures.
• Torticollis – The involuntary turning of the neck to one side that can be seen in disorders of the basal ganglia.
• Toxoplasmosis – A parasitic disease that affects the brain that occurs in patients who are immunosuppressed (such as those individuals with AIDS)
• Tracheostomy – A temporary surgical opening at the front of the throat providing access to the trachea or windpipe to assist in breathing.
• Transducer – A sensitive electronic device which detects bodily functions, such as heart rate and blood pressure, and transmits signals representing those functions to a monitor so that they can be observed.
• Thoracic – Refers to the chest area. The thorax runs between the abdomen and neck and is encased in the ribs.
• Toxicology – The branch of medicine that deals with the effects, detection, and treatment of poisons.
• Traction – The use of a pulling force to treat muscle and skeleton disorders.
• Transverse Plane – The plane orthogonal to the anteroposterior or oral-aboral axis.

U

• Ultra Sound – A diagnostic medical imaging technique used to visualize muscles, tendons, and many internal organs, to capture their size, structure and any pathological lesions with real time tomographic images.
• Uncovertebral – Pertaining to the uncinate processes of a vertebra.
• Unilateral – Pertaining to only one side.

V

• Ventricles, Brain – Four natural cavities in the brain which are filled with cerebrospinal fluid. The outline of one or more of these cavities may change when a space-occupying lesion (hemorrhage, tumor) has developed in a lobe of the brain.
• Ventriculostomy – A procedure for measuring intracranial pressure by placing a measuring device within one of the fluid-filled, hollow chambers of the brain.
• Verbal Apraxia – Impaired control of proper sequencing of muscles used in speech (tongue, lips, jaw muscles, vocal cords). These muscles are not weak but their control is defective. Speech is labored and characterized by sound reversals, additions and word approximations.
• VER (Visual Evoked Responses) – Measures function of Central Nervous System, including the pathway from optic tract.
• Vertebrae – Bones that make up the spinal column.
• Vertigo – Dizziness or imbalance that often has a spinning or rotational component.
• Vestibular – Pertaining to the vestibular system in the middle ear and the brain which senses movements of the head. Disorders of the vestibular system can lead to dizziness, poor regulation of postural muscle tone and inability to detect quick movements of the head.
• Vestibular System – The parts of the nervous system that control equilibrium and balance.

W

• White Matter – The lipid rich myelinated portion of the brain and spinal cord.

X

Y

Z