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Medical Terms

Here at Neurology Associates, we understand that many patients can feel overwhelmed by the use of medical terminology. That is why we make this "Medical Terminology Dictionary" available for your use. We hope you enjoy!

A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z

Click on one of the letters above to jump straight to that portion of the dictionary!

ADHD ADHD is a syndrome generally characterized by inattention, distractibility, impulsivity and hyperactivity. ADHD is common in both children and adults. Many factors contribute to ADHD including physical factors, problems surrounding pregnancy, genetic factors, diet, and infant malnutrition.
Advanced Sleep Phase Syndrome A circadian rhythm disorder in which phases of the daily sleep/wake cycle are advanced with respect to clock time. The sleep phase occurs well ahead of conventional bedtime, creating a tendency to fall asleep or wake up too early.
Alpha Rhythm An EEG brainwave produced when an individual is in a relaxed awake condition with their eyes closed. The frequency is 8-13 Hz in human adults, and is predominately present in the occipital lobe of the brain. It indicates the awake state in most normal individuals.
Alpha Sleep Sleep in which alpha activity occurs with sleep EEG patterns.
Alpha-Delta Sleep On rare occasions, Delta brainwaves (deep sleep) are mixed with alpha brainwaves (relaxed wakefulness). Alpha-delta sleep occurs with conditions such as arthritic pain, stimulant use and thyroid imbalance.
Alzheimer’s Alzheimer’s disease is a degenerative disease of the brain from which there is no recovery. The disease slowly attacks nerve cells in all parts of the brain’s cortex as well as some surrounding structures thereby impairing a person’s abilities to govern emotions, recognize errors and patterns, coordinate, movement, and remember. Two significant abnormalities occur in the brain affected by Alzheimer’s: twisted nerve cell fibers, known as neurofibrillay tangles and a sticky protein called beta amyloid.
Ambulatory EEGs AEEG is a technology that allows 72-hour monitoring of a patient in the home setting. The chances of recording an ictal event over this prolonged time period are increased versus other 24-hour alternatives. Ambulatory electroencephalography is less expensive than most inpatient monitoring as well.
Ambulatory Monitor Portable system used for the continuous recording of multiple physiological variables during sleep.
Amnesia Loss of memory. Types of amnesia include: anterograde Loss of memory of events that occur after the onset of the etiological condition or agent. retrograde Loss of memory of events that occurred before the onset of the etiological condition or agent.
Apnea Cessation of breathing for 10 or more seconds during sleep. There are two basic types of sleep apnea: Obstructive Apnea is caused by a closure of the air passage despite efforts to breathe; Central Apnea is a lack of effort to breathe. Obstructive Sleep Apnea is by far the most common type. True apnea during wakefulness is extremely rare.
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Benzodiazepines Class of sedative medication commonly used to treat anxiety and insomnia.
Beta Activity Brain waves seen in alert wakefulness which have a frequency greater than 13 Hz (Hertz).
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Carpal Tunnel Syndrome This condition presents with burning, tingling, itching and or numbness in the palm of the hand and the fingers especially the thumb, the index and the middles fingers. Carpal Tunnel occurs when the median nerve which runs from the forearm into the hand, becomes pressed or squeezed at the wrist. Thickening from the irritated tendons or other swelling narrows the tunnel and causes the median nerve to be compressed.
Central Nervous System (CNS) The brain and spinal cord.
Central Sleep Apnea A period of at least 10 seconds without airflow, during which no respiratory effort is evident.
Chronotherapy Treatment of a circadian rhythm sleep disorder by systemically changing sleeping and waking times to reset the patient's biological clock.
Circadian Any periodicity that is near but not necessarily exactly 24 hours.
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Delayed Sleep Phase Syndrome A circadian rhythm disorder, which in the daily sleep/wake cycle, is delayed with respect to clock time. Accordingly, the sleep phase occurs well after the conventional bedtime. Usually associated with difficulty getting up in the morning.
Diagnostic Sleep Study Continuous monitoring of several physiological activities in a sleeping individual. Usually carried out to determine the absence or presence of a specific sleep disorder. A diagnostic sleep study can be performed in a sleep disorders center or in a patient's home with portable recording equipment.
Drowsiness, Drowsy A state of quiet wakefulness that typically occurs prior to sleep onset. If the eyes are closed, diffuse and slowed alpha activity usually is present, which then gives way to early features of stage 1 sleep.
Déjà vu A paramnesia consisting of the sensation or illusion that one is seeing what one has seen before.
Dyslexia Inability or difficulty in reading, including word-blindness and a tendency to reverse letters and words in reading and writing.
Dyssomnia Primary disorders of sleep or wakefulness characterized by insomnia or hypersomnia as the major presenting symptom. Dyssomnias are disorders of the amount, quality, or timing of sleep.
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Electrocardiography (EKG) (ECG) Method of measuring the electrical activity of the heart. EKG is continuously recorded in both diagnostic sleep studies and CPAP titration sleep studies.
Electrodes Small devices that transmit brain waves or other biological electrical signals from a patient to a polysomnograph machine, where the signal is amplified and displayed.
Electroencephalogram (EEG) A recording of the electrical activity generated by the brain. Brain wave frequencies are expressed in hertz (Hz) or cycles per second (cps), and amplitude is expressed in microvolts. Characteristic frequency and amplitude patterns of the activity define which stage of sleep the patient is experiencing. Brain waves are recorded in both diagnostic and CPAP titration sleep studies.
Electromyogram (EMG) A recording of the electrical activity of the muscles. The absence of very low level of EMG activity indicates the presence of REM sleep. Very high levels can help identify periods of wakefulness. Non-invasive EMG is recorded in both diagnostic and CPAP titration sleep studies.
Epilepsy Epilepsy is a brain disorder in which clusters of nerve cells, or neurons, in the brain sometimes signal abnormally. The result can be seizures, and strange sensations, emotions, behavior and loss of consciousness. Epilepsy can be caused by illness, brain damage, and abnormal brain development. Often abnormal brain wiring or a chemical imbalance (neurotransmitters) can contribute. Persons experiencing two or more seizures are considered to have Epilepsy.
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Fatigue A feeling of tiredness or weariness usually associated with performance decrements.
Fibromyalgia FM is a chronic pain illness characterized by widespread musculoskeletal aches, pain and stiffness, soft tissue tenderness, general fatigue and sleep disturbances. The most common sites of pain include the neck, back, shoulders, pelvic girdle and hands, but any body part can be involved. Fibromyalgia patients experience a range of symptoms of varying intensities that wax and wane over time.
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GABA (Gamma-Amniobutyric Acid) A major inhibiting compound (neurotransmitter) in the brain, which is considered to be involved in muscle relaxation, sleep, diminished emotional reaction and sedation. GABA is released in the greatest amount from the cerebral cortex during slow wave sleep.
Gastroesphageal Reflux Disease (GERD) The flow of stomach acid upwards into the esophagus, which can cause arousals and disrupt sleep.
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Hypersomnia Excessive sleepiness, as evidenced by prolonged nocturnal sleep, difficulty maintaining an alert awake state during the day, or undesired daytime sleep episodes. ideas of reference The feeling that casual incidents and external events have a particular and unusual meaning that is specific to the person. This is to be distinguished from a delusion of reference, in which there is a belief that is held with delusional conviction.
Hypnagogic Referring to the semiconscious state immediately preceding sleep; may include hallucinations that are of no pathological significance.
Hypnopompic Referring to the state immediately preceding awakening; may include hallucinations that are of no pathological significance.
Hyoid Suspension Surgical procedure sometimes used in the treatment of sleep apnea or snoring. It is designed to improve the airway behind the base of the tongue. The hyoid bone is located in the neck where some tongue muscles attach. If the hyoid bone containing these muscles is pulled forward in front of the voice box, it can open the airway space behind the tongue. This is performed under local intravenous sedation or general anesthesia, and requires a one or two day hospital stay.
Hypnic Jerk Sensation of falling, and then "jerking" awake just as one drifts to sleep. It is a normal sensation experienced by many people.
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Insomnia A subjective complaint of difficulty falling or staying asleep or poor sleep quality.
Initial Insomnia Difficulty in falling asleep.
Inappropriate Sleep Episodes Periods of sleep that are not planned and often occur in an unsafe situation (i.e., while driving). These episodes are always due to sleep deprivation.
"Intermediary" Sleep Stage" A term sometimes used for non-REM stage 2 sleep.
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Jet Lag A disturbance induced by a major rapid shift in environmental time during travel to a new time zone. Symptoms include fatigue, sleep and impaired alertness.
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K Complex An EEG waveform most commonly found in stage 2 sleep. It has a well-delineated negative sharp wave that is immediately followed by a slower positive component.
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Leg Movement Leg movements are recorded in diagnostic sleep studies to test for Periodic Limb Movement Disorder.
Limit-Setting Sleep Disorder Occurs when a child stalls or refuses to go to bed, and subsequently does not receive enough sleep.
Linear Sleepiness Rating Scale A measure of subjective sleepiness. The scale consists of a horizontal line, 100 mm in length on which the right extreme is labeled "Very Sleepy" and the left extreme is labeled "Very Wide Awake."
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Middle insomnia Awakening in the middle of the night followed by eventually falling back to sleep, but with difficulty.
Melatonin A hormone secreted by the pineal gland in the brain. Melatonin has been reported to have hypnotic properties, leading some to suggest that melatonin, which is released at night, may be an endogenous sleep inducer.
Multiple Sclerosis MS is an unpredictable and incurable disease of the central nervous system. The condition can range from relatively benign to somewhat disabling to devastating, as communication between the brain and other parts of the body is disrupted. Many investigators believe MS to be an autoimmune disease -- one in which the body, through its immune system, launches a defensive attack against its own tissues. In the case of MS, it is the nerve-insulating myelin that comes under assault. Such assaults may be linked to an unknown environmental trigger, perhaps a virus.
Multiple Sleep Latency Test (MSLT) The standard test used to quantify the overall daytime sleep tendency by measuring the speed of falling asleep (sleep latency) usually in 5 tests carried out at two-hour intervals. This test also helps in the diagnosis of narcolepsy. Patients with narcolepsy often go directly from wakefulness to REM, which can be evaluated with the MSLT.
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Narcolepsy A sleep disorder characterized by excessive sleepiness, cataplexy, sleep paralysis, hypnagogic hallucinations, and an abnormal tendency to pass directly into REM sleep from wakefulness. It was recently found to be caused by an abnormal gene in the brain.
National Commission on Sleep Disorders Research Created by the U.S. Congress in 1990, the commission conducted a comprehensive study of the social and economic impact of sleep disorders in America, and made recommendations based on its findings to Congress in January of 1993.
NCVs NCV is a Nerve conduction velocity (NCV) test of the speed of conduction of impulses through a nerve. The nerve is stimulated, usually with surface electrodes, which are patch-like electrodes (similar to those used for ECG) placed on the skin over the nerve at various locations. One electrode stimulates the nerve with a very mild electrical impulse. The resulting electrical activity is recorded by the other electrodes. The distance between electrodes and the time it takes for electrical impulses to travel between electrodes are used to calculate the nerve conduction velocity.
Neurology A specialized branch of medicine that deals specifically with the nervous system and its diseases.
Neuropsych Tests Neuropsychological tests are noninvasive; that is, they do not involve attaching you to machines or using X-rays. Commonly, the tests involve a question-and-answer format and/or working with materials on a table. Some tests are administered using a computer. Clinical Neuropsychologists use this knowledge to assist in the assessment, diagnosis, and treatment of patients.
Neurotransmitters Endogenous chemical components that are released from axon terminals of one neuron and transmit the signal to the next neuron by combining with its receptor molecules. Examples of neurotransmitters that appear to be important in the control of sleep and wakefulness include: norepinephrine, serotonin, acetylcholine, dopamine, adrenaline and histamine. The process of neurotransmission may be inhibited, modulated, or enhanced by other chemical mediators within the brain, or by exogenous pharmaceuticals.
Nightmare An unpleasant and/or frightening dream that usually awakens a person from REM sleep. Occasionally called a dream anxiety attack, it is not synonymous with a night (sleep) terror.
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Obesity-Hypoventilation Syndrome A term applied to obese individuals who have abnormally slow and shallow respiration (hypoventilation) during wakefulness, resulting in an increased level of carbon dioxide in the blood.
Obstructive Hypopnea Periodic, partial closure of the throat during sleep resulting in reduced air exchange. The medical consequences of this partial closure can be as severe as sleep apnea (full closure of throat) Usually characterized by snoring, excessive daytime sleepiness, and other symptoms of fatigue
Obstructive Sleep Apnea Repetitive cessation of breathing during sleep for 10 seconds or more due to complete closure (collapse) of the throat. Usually characterized by snoring, excessive daytime sleepiness, and other symptoms of fatigue.
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Paramnesia A disorder of memory in which dreams or fantasies are confused with reality.
Parasomnia Abnormal behavior or physiological events occurring during sleep or sleep-wake transitions.
Parkinson’s Disease Parkinson's disease is a slowly progressive disorder that affects movement, muscle control, and balance. It occurs when cells are destroyed in certain parts of the brain stem, particularly the crescent-shaped cell mass known as the substantia nigra. The primary cause of Parkinson’s is unknown. Although it is clear that dopamine deficiency is the primary defect in Parkinson's disease, researchers now must discover how this dopamine is lost. Symptoms often start with an occasional tremor in one finger that spreads over time to involve the whole arm.
Periodic Limb Movement Disorder Also known as Periodic Leg Movements of Sleep and Nocturnal Myoclonus. Characterized by periodic episodes of repetitive limb movements during sleep. The movements are often associated with a partial arousal or awakening; however, the patient is usually unaware of the limb movements or frequent sleep disruption. There can be marked night-to-night variability in the number of movements.
Persistent Insomnia Continuing insomnia that responds poorly to treatment.
Polysomnogram A continuous and simultaneous recording of multiple physiological variables during sleep.
Polysomnograph A biomedical instrument for the measurement of multiple physiological variables of sleep. It records the sleep physiological parameters of EEG, EOG, EMG, EKG, respiratory airflow, respiratory movements, leg movements, and other parameters depending on the situation.
PSG A polysomnograph is a test of sleep cycles and stages through the use of continuous recordings of brain waves (EEG), electrical activity of muscles, eye movement (electrooculogram), breathing rate, blood pressure, blood oxygen saturation, and heart rhythm and direct observation of the person during sleep. There are two states of sleep: non-rapid eye movement (NREM) sleep and rapid eye movement (REM) sleep. REM sleep alternates with NREM sleep approximately every 90 minutes. A person with normal sleep usually has four to five cycles of REM and NREM sleep during a night.
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Quiet Sleep The term frequently used instead of NREM sleep in describing the sleep of infants. Quiet/NREM sleep comprises 50% of a newborns' total sleep time.
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Rapid Eye Movement Sleep (REM Sleep) The sleep stage in which vivid dreaming occurs; identified by the occurrence of rapid eye movements under closed eyelids, motor atonia and low voltage EEG patterns. Also associated with bursts of muscular twitching, irregular breathing, irregular heart rate, and increased autonomic activity.
Restless Legs Syndrome The sleep disorder characterized by tingling, creeping, crawling, or aching sensation in the legs that tends to occur when an individual is not moving. There is an almost irresistible urge to move the legs that relieve the sensations. Inability to remain at rest can result in severe sleep disturbance.
Restlessness (Referring to Quality of Sleep) Persistent or recurrent body movements, arousals, or brief awakenings in the course of sleep.
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Sleep Terror Disorder One of the parasomnias, characterized by panic and confusion when abruptly awakening from sleep. This usually begins with a scream and is accompanied by intense anxiety. The person is often confused and disoriented after awakening. No detailed dream is recalled, and there is amnesia for the episode. Sleep terrors typically occur during the first third of the major sleep episode.
Serotonin A neurotransmitter in the brain that modulates mood, appetite, sexual activity, aggression, body temperature and sleep.
Sleep Overall state in which an individual rests quiescently in a recumbent position, disengages from the environment, and become unresponsive to stimuli.
Sleep Apnea Cessation of breathing for 10 or more seconds during sleep. There are two basic types of sleep apnea: Obstructive Apnea is caused by a closure of the air passage despite efforts to breathe; Central Apnea is a lack of effort to breathe. Obstructive Sleep Apnea is by far the most common type.
Sleep Architecture The sequence and duration of each sleep stage and awakening during a sleep period. Often displayed in the form of a histogram.
Sleep Cycle The progression through an orderly succession of sleep states and stages. In a healthy adult, the first cycle is always initiated by going from wakefulness to non-REM sleep. The first REM period follows the first period of non-REM sleep to complete the first sleep cycle. The two sleep states continue to alternate throughout the night with an average cycle period of about 90 minutes. A full night of normal human sleep will usually consist of 4-6 non-REM/REM sleep cycles.
Sleep Debt The result of recurrent sleep deprivation that occurs over time, when an individual does not obtain a sufficient amount of restorative daily sleep. Sleep debt is like a monetary debt; it must be paid back at some time. The larger the sleep debt, the stronger the tendency to fall asleep. This accumulation of "lost sleep" may contribute to a decreased quality of life, the onset of related health problems, and the increased risk of injury and/or accident. See Sleep Deprivation.
Sleep Deprivation An acute or chronic lack of sufficient sleep, which causes a person to feel unrefreshed during wakefulness.
Sleep Disorders A broad range of illnesses arising from many causes, including; dysfunctional sleep mechanisms, abnormalities in physiological functions during sleep, abnormalities of the biological clock, and sleep disturbances that are induced by external factors.
Sleep Hygiene Behavioral activities that either contribute to or detract from restorative sleep. Good sleep hygiene would include activities such as going to bed the same time each night, restricting caffeine intake, and avoiding napping during the day.
Snoring Sounds made during sleep caused by breathing vibrations in the pharynx. In the diagnosis of obstructive sleep apnea, snoring volume and frequency of occurrence often correlate with the severity of the condition. Snoring noise is recorded in both diagnostic sleep studies and CPAP titration studies.
Strokes A stroke has the same relationship to the brain as a heart attack does to the heart; both result from a blockage in a blood vessel that interrupts the supply of oxygen to cells, thus killing them. A stroke is usually defined as either ischemic or hemorhagic, depending upon whether it is caused by a blockage in an artery or by a tear in the artery's wall that produces bleeding in the brain.
Systemic Lupus Erythematosus Lupus is an autoimmune disease in which the immune system turns against parts of the body it is designed to protect leading to inflammation and damage to various body tissues. The cause of Lupus is unknown. It can affect joints, skin, kidneys, heart, lungs, blood vessels, and brain. Common symptoms include extreme fatigue, painful or swollen joints (arthritis), unexplained fever, skin rashes, and kidney problems. Lupus can run in families indicating a genetic basis however additional factors may include sunlight, stress, certain drugs, and infectious agents such as viruses.
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Terminal insomnia Awakening before one's usual waking time and being unable to return to sleep.
Therapeutic Botox Botulinum toxin injection therapy (also known as "BOTOX® therapy") is used to treat dystonia—a neuromuscular disorder that produces involuntary muscle contractions, or spasm—that affects muscles that control movement in the eyes, neck, face, voice box, or the smooth muscle in the bladder. The goal of the therapy is to reduce muscle spasm and pain. This potent neurotoxin is produced by Clostridium botulinum, a bacterium that causes food poisoning (botulism). Botulinum toxin has proven to be useful in the treatment of many forms of dystonia. Neurons generate new nerve endings that reactivate the dystonia, so improvement is not long lasting, and treatment is usually repeated every 3 to 4 months.
Thoracic Excursion Thoracic (chest) movement, which indicates respiratory effort. This is recorded in diagnostic sleep studies, and is typically measured by the placement of a sensor band around the chest. The sensor band records chest wall movement associated with respiration. This measurement is used in differentiating the type of sleep apnea.
Transient Insomnia Difficulty sleeping for only a few nights.
Trigger Points A trigger point is a knot or tight, ropy band of muscle that forms when muscle fails to relax. The knot often can be felt under the skin and may twitch involuntarily when touched (called a jump sign). The trigger point can trap or irritate surrounding nerves and cause referred pain — pain felt in another part of the body. Scar tissue, loss of range of motion, and weakness may develop over time. TPI is used to alleviate myofascial pain syndrome (chronic pain involving tissue that surrounds muscle) that does not respond to other treatment. Many muscle groups, especially those in the arms, legs, lower back, and neck, are treated by this method.
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Unintended Sleep Episode A sleep episode that is not planned and may happen during an activity in which such an episode is hazardous, such as when driving a car or working with machinery.
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Wake Time The total time scored as wakefulness in a polysomnogram occurring between "lights out" and final awakening.
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Zeitgeber An environmental time cue that entrain biological rhythms to a specific periodicity. Known Zeitgebers are light, melatonin and physical activity. To be effective, these signals must occur when the biological clock is in a responsive phase.

Check out these great links below! These websites provide information that you might find
helpful and informative.

American Academy of Neurology The official website of the American Academy of Neurology
Neurology Reference Library A great reference site maintained by the creators of WebMD. Find answers to all your Neurological questions.
The American Board of Neurology Certifying organization for neurologists
WebMD A great website on an endless variety of topics.
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