Parent Support for Children with Challenges - Definitions

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

labeling: The classification and application of a name to a set of symptoms, characteristics, behaviors, and traits. In medicine, such a process is termed diagnosis. Although few challenge the necessity of such "classification" processes for appropriate treatment and planning, many contend that such labels-particularly in the behavioral area-become pejorative, a basis for discrimination, and perhaps even serve as self-fulfilling prophecies. Thus, the description "a mentally retarded adult" has now been discarded in favor of "person with mental retardation," which shifts the focus from "mentally retarded" to "person."
labile: unstable, fluctuating.
labyrinth: Inner ear; composed of the cochlea (concerned with hearing) and the vestibule and semicircular canals (concerned with balance and equilibrium). The control of balance and equilibrium is complex, and it is inappropriate to automatically attribute problems in these areas to labyrinthine dysfunction in the absence of more specific diagnostic resting.
labyrinthine righting reflex: The reflex tendency of the head to move toward an upright vertical position; this reflex can be assessed in a variety of positions from tilted upright supported sitting (head control) to vertical upside-down suspension, as well as many oblique positions.
LAC: See Lindamood Auditory Conceptualization Test.
laceration: Tear.
lacrimal duct stenosis, congenital: Dacryostenosis; blockage of the tear duct, which can lead to eye irritation and infection.
LAD: See language acquisition device.
lallation: Sound imitation in infancy; primitive echolalia (repetition of what is heard) not necessarily specific to the sounds heard; describes repetitive vocalizations made between 6 and 9 months of age.
lalopathy: Rarely used term for any type of speech disorder.
Landau reflex: Precipitation reflex; a postural response that emerges between 2 and 3 months of age, in which an infant held in prone (front) suspension succeeds in raising his or her head to a vertical position with subsequent trunk, hip, and leg extension. The Landau is a prerequisite to voluntary rolling over; it is delayed in the presence of hypotonia (decreased muscle tone).
Landau-Kleffner syndrome: A rare form of seizure disorder manifested as acquired aphasia (loss of language skills); it may also need to be considered in some presentations of autism. It generally begins with one or more seizures between the ages of 5 and 6 years. First, language comprehension is abruptly lost, followed by a gradual loss in expressive language. The seizures generally do not continue, although the electroencephalogram (EEG) remains abnormal. There may be spontaneous improvement or improvement with anticonvulsant therapy.
Langer-Giedion syndrome: A genetic syndrome with mental retardation, growth deficiency, a peculiar facies with a bulbous nose, sparse scalp hair, loose skin, short fingers, and exostoses (tumors' bumps) of the long bones. Inheritance is possibly antosomal dominant, with most cases representing new mutations; a deletion on the long arm of chromosome 8 (8q deletion) has been observed. Sometimes referred to as trichorhinophalangeal syndrome II. (Trichorhinophalangeal syndrome has the same hair, nose, and ringer abnormalities, but tends to lack the exostoses, mental retardation, and short stature.)
language acquisition: The process ot learning to communicate effectively and appropriately in a transactional context. This includes knowledge of syntax (grammar), semantics (the meaning of words), and pragmatics.
language acquisition device (LAD): The set of linguistic processing skills that enables a child to infer the rules in the speech of others and then use these rules to generate language; LAD is thought to be innate.
language delay: Communication skills not developing commensurately with the advance of chronological age. Includes the diagnostic subgroups of language disorder, language and learning disability, mental retardation, and autism.
language disorder: A developmental disorder involving disabilities of reception, integration, recall, and/or production of language. Language disorders may be spoken, written, or both.
language experience approach to reading: An instructional approach that combines listening, speaking, writing, and reading skills in a single program. This approach assumes that a child learns the following reasoning: What 1 am thinking about, I can talk about; What I can talk about, I can write (or dictate); What is written, I (and others) can read; and I can read what others have written. Instruction begins with a discussion of what is to be written. The teacher then writes what the student dictates, resulting in an individual story or an experience chart, winch then becomes the basic instructional material used for teaching the student to read. Advocates of this approach suggest that the students' level of interest is higher than with other methods because 1) students are reading about something that actually happened, and 2) they tend to learn material based on their personal word patterns faster than those contrived by others. There is some concern that students may practice faulty language patterns and may not receive enough encouragement to learn new words. Perhaps the greatest area of controversy revolves around whether this method includes direct, systematic instruction of skills, particularly phonics. Critics contend that children cannot learn to read if they have not mastered phonics, and all children, especially those at risk, need systematic instruction in phonics. Advocates claim that phonetic instruction does occur, hut within a meaningful context. The emphasis on student writing requires students to actually spend more time applying phonics knowledge than is found in a traditional program.
language, expressive: A coded system for communication with another person or people. Speaking, writing, and signing are expressive language skills.
Language Processing Test, The (LPT): A language test for 5- to 11-year-olds that assesses associations, categorization, similarities, differences, multiple meanings, and attributes. LPT analysis yields information regarding processing limitations such as word retrieval difficulties, inappropriate word substitutions, nonspecific word usage, inability to correct errors, response avoidance, rehearsing responses, and unusual pauses.
lanugo: Primary hair; the fine downy hair that covers the entire fetus from mid-gestation to term; lanugo is replaced by yellus, or secondary hair, at term.
large for gestational age (LGA): An infant whose birth weight is above the 90th percentile for age. This condition may be constitutional (the baby comes from physically large parents) or related to conditions such as maternal diabetes or Beckwith syndrome. Mechanical birth injuries (injuries secondary to the physical difficulty of delivering a large baby) are more common in LGA babies.
larynx: The upper part of the trachea (windpipe); it contains the vocal cords.
last menstrual period (LMP): A date used in calculating the due date of a pregnancy.
latency: A term from behavioral learning theory referring to the time that elapses between an operant behavior and a consequent stimulus event (CSE). The shorter the latency, the easier it is to make an association between the operant and the CSE. For example, if the behavior to be strengthened is "lining up quietly," then children who line up quietly should be recognized (i.e., rewarded) immediately, not at the end of the day.
latency: The elementary school-age period from 4-6 to 11-13 years of age. It is named for the latency, or relative inactivity, of the sexual drive between the resolution of the so-called Oedipus complex and the onset of puberty. During latency the sexual drive is sublimated into social learning.
laterality: Awareness of and ability to use both sides of the body; the recognition of the existence of both the left and right sides of the mid-line. By 5 years of age, most children discriminate between their left and right. The ability to perform a task involving both sides on demand (touching their right knee with their left hand) appears around 7 years of age, whereas the ability to identify the left and right of another person positioned opposite them usually occurs by 9 years of age. Children with problems involving laterality may have difficulty with certain learning tasks (e.g., reading) and can display other forms of visual-spatial orientation deficits, but laterality training docs not necessarily improve reading skills.
Laurence-Moon-Biedl syndrome: See Bardet-Biedl syndrome (the original cases reported by Laurence and Moon had spastic diplegia [paralysis on both sides of the body] and lacked polydactyly [extra fingers or toes]).
LBW: See low birth weight.
L.C.S.W.: See Licensed Clinical Social Worker.
LD: See learning disability.
LDA: See Learning Disabilities Association of America.
lead line: On physical examination, a blue line on the gums; on an X ray, a thin line at the growing end of the bone; both lines are indicative of (past) lead poisoning.
lead poisoning: Plumbism. A heavy metal found in old interior paint (made before 1950) and in exhaust from leaded gasoline that is toxic to the nervous system. Lead poisoning is most commonly found in children 1-6 years of age who live in old, deteriorating, inner-city buildings. These children put paint chips, toys, dust, and dirt that often have a high lead content in their mouths (i.e., pica). Remodeling of old buildings with poor ventilation can dramatically increase the airborne lead level, producing toxic levels from inhalation alone. The lead is absorbed through the intestine and into all the tissues in the body. Any level of lead toxicity can probably cause permanent brain damage. The entire range of developmental disorders has been described as symptomatic of lead poisoning, including mental retardation, language disorders, learning disabilities and other school problems, autism, and attention-deficit/ hyperactivity disorder (ADHD). Lead levels over 40 micrograms per cubic centimeter have been clearly associated with central nervous system (CNS) impairment and a poor developmental outcome. The effects of low (or subclinical) levels of lead are debated. Lead generally causes anemia by blocking iron binding; anemia also contributes to poor attention span. Treatment involves two goals: 1) prevention through the removal of lead from the environment; and 2) chelation to reduce the lead burden by removing lead from the body and brain, with iron supplementation to treat the anemia.
learned helplessness: Failure to respond appropriately to a situation due to previous experience with uncontrollable events in the same or similar situations. The concept combines a behaviorist approach to mastery of the environment with the psychoanalytic concept of inferiority and the humanistic concept of motivation. Learned helplessness is characterized by cognitive and affective disturbances that undermine a person's desire or motivation to respond, distort the ability to perceive success and to learn that responding can work, and result in heightened emotionality due to anxiety and depression. It is not merely the perceived lack of control but (mis)understanding of why one lacks control that encourages learned helplessness. Thus, students with learning disabilities and mental retardation view their failures as being due to their lack of ability despite possessing the skills required to accomplish the task. These children often say, "I can't" or "I'm dumb," or are hesitant to even begin a task for fear of being unable to complete it or do it correctly. Some attributions play a central role in the acquisition and maintenance of learned helplessness. Students must be directly taught to ascribe their learning difficulties to factors they can affect. In addition to classroom intervention, supportive counseling or group therapy can further address issues of self-esteem and depression.
learning disability (LD): A disorder in one or more of the basic psychological processes involved in understanding or using language, spoken or written: the disorder may manifest itself in imperfect ability to listen, think, speak, read, write, spell, or do mathematical calculations. Learning disabilities include such conditions as perceptual disabilities, brain injury, minimal brain dysfunction, dyslexia, and developmental aphasia (loss of language skills). According to PL 94-142/PL 101-476, the term does not include children who have learning problems that are primarily the result of visual, hearing, or motor disabilities; mental retardation; emotional disturbance; or environmental, cultural, or economic disadvantage. Because many different tests, standards, and criteria have been used to operationalize these definitions, a student may be classified as having a learning disability in one area but not in another. According to a definition of learning disabilities developed by the National Joint Council on Learning Disabilities in 1981, these disorders are intrinsic to the individual and are presumed to be due to central nervous system dysfunction. Even though a learning disability may occur concomitantly with other handicapping conditions (e.g., sensory impairment, mental retardation, social and emotional disturbance) or environmental influences (e.g., cultural differences, insufficient/inappropriate instruction, psychogenic factors), it is not the direct result of those conditions or influences.

The definition of learning disability subscribed to by the Learning Disabilities Association of America includes the effect of the disability on self-esteem, education, vocation, and daily living activities. The concept of learning disabilities, as it has evolved, reflects a range of neurological dysfunctions that may be manifested in various aspects of life, are innate in the individual, and are" lifelong. However, people with learning disabilities can learn to compensate, attend college, and have successful careers.
Learning Disabilities Association of America (LDA): A nonprofit organization formed to advance the education and general welfare of children and adults of normal or potentially normal intelligence who have learning disabilities. The organization was founded by parents of children with learning disabilities in 1964 as the Association of Children with Learning, Disabilities (ACLD). The name was subsequently modified to include both "Children and Adults," but the acronym remained the same. In 1990, the name was officially changed to the Learning Disabilities Association of America (LDA). The LDA holds international and national annual conventions. Newsbriefs, the official LDA newsletter, is published six times yearly.
Learning Potential Assessment Device (LPAD): A clinical battery of 14 instruments devised by Reuven Feuerstein. Using adaptations from Raven's Progressive Matrices, Organization of Dots, Plateaux Tests, representational stencil design tests, numerical progressions, positional learning, and verbal and figural analogy tests, the LPAD is a dynamic assessment that focuses on the process rather than the product of learning and on the qualitative rather than quantitative aspects of the individual's thinking.
learning style: The manner in which an individual learns most efficiently. In addition to preferred cognitive style, learning style also includes environmental variables, such as lighting, noise level, snacking, time of day, and position.
Learning-Style Inventory (LSI): A brief 12-item questionnaire that characterizes how an individual learns and deals with ideas and day-to-day situations; scores on four learning stages (concrete experience, reflective observation, abstract conceptualization, and active experimentalization) are used to graphically locate the individual's learning style.
least restrictive environment (LRE): Term used in PL 94-142, the Education for All Handicapped Children Act of 1975, to stress the importance of attending school in the most natural and integrated setting possible considering the student's individual needs. The least restrictive environment is one that allows the child to participate in general education programs as much as possible while meeting his or her special needs. The justifications for this include questions regarding the efficacy of special class placement and the idea that children with disabilities would benefit from exposure to typical role models. However, the least restrictive environment may also be used administratively as an excuse to provide minimal special services. Used appropriately, the term stresses the need to find an optimal placement for each child within a continuum of services.
Leber congenital amaurosis: A genetic syndrome with progressive blindness (an infant form of retinitis pigmentosa [night blindness and progressively restricted visual field]), mental retardation, and kidney disease. Incidence is 2.5 in 100,000. In most cases, inheritance is autosomal recessive.
legally blind: A condition in which an individual has less than 20/200 vision (can see at 20 feet what can typically be seen at 200 feet) in his or her better eye, or a very limited field of vision (20 degrees at its widest point).
leiotrichous: Straight hair, as found in the Mongoioid races.
Leiter International Performance Scale (LIPS): Individually administered test of global intelligence. The test requires no language usage for either administration or response. It is suitable for people 2 years of age through adult, although it is used primarily for children with suspected language delays. The tasks range from matching colors and forms to the completion of complex patterns, analogous designs, and classification of objects. The test is especially helpful for people with profound hearing impairment and language impairment and non-English-speaking persons. Differences between the scores achieved by children with language impairments on the Peabody Picture Vocabulary Test-Revised and on the Leiter may help to illuminate the severity of their language impairments. The test takes approximately 40 minutes to administer and provides an intelligence quotient by the ratio method. The Leiter should be used only as a supplementary measure of intelligence, since its norms are outdated and originate from a non-standardized normative group. However, the LIPS is helpful in obtaining a nonverbal measure of ability to compare with results obtained by other measures.
Lennox-Gastaut syndrome: Atonic-astatic epilepsy. A syndrome of different types of seizures, including typical absence seizures with myoclonic, clonic, tonic, and atonic seizures present in one individual. It is characterized by frequent seizures, including status epilepticus, that are difficult to control. The electroencephalogram (EEG) generally shows multifocal abnormalities with abnormal background activity and a spike and wave pattern of less than 3 per second. Mental retardation is common, and the syndrome occurs frequently in children who have had previous encephalopathy (brain damage due to lack of oxygen). Lennox-Gastaut can evolve from hypsarhythmia (a continuous disorganized pattern of high-voltage slow-waves [a rounded curve deviation] and spikes [a sharp pointed deviation]).
lens: Transparent material designed to form an image. Lenses are used to correct vision both in (contact lenses) and outside of (glasses) the eye. The transparent surface that focuses light rays upon the retina (light-sensitive inner back wall) is the eye's lens.
Lenz-Majewski hyperostosis syndrome: Craniodiaphyseal dysplasia, Lenz-Majewski type; a syndrome with poor growth, mental retardation, a peculiar facies, atrophic (thin) skin, sparse hair, syndactyly (webbing of the fingers or toes), and dense, thick bones. Etiology (cause) is possibly autosomal dominant; association with advanced paternal age noted.
LEOPARD syndrome: See multiple lentigines svndrome.
leprechaunism: Donohoe syndrome; a genetic syndrome with growth deficiency, marked absence of subcutaneous (inner) fat, an elfin facies, severe failure to thrive, hypoglycemia (low blood sugar level), and early death. Inheritance is autosomal recessive. The name derives from the dwarf cobblers of Irish folklore.
LES: See lower esophageal sphincter.
Lesch-Nyhan syndrome: Lesch-Nyhan disease; a disorder of purine metabolism that causes a progressive syndrome including profound mental retardation, choreoathetosis, and marked self-injurious behavior. Inheritance is X-linked.
lesion: Injury; local tissue discontinuity, sometimes with loss of function.
Let's Talk Inventory for Adolescents (LTI-A): An age-normed (in 2-year intervals) language scale for people 9 years to young adulthood that helps identify inadequate or delayed social-verbal communication skills. The LTI-A looks at the ability to formulate speech acts appropriate to pictured situational contexts for the functions of ritualizing, informing, controlling, and feeling. Stimulus pictures present interactions with adolescent peers and with an authority figure.
Let's Talk Inventory for Children (LTI-C): An age-normed language scale for preschool and early elementary-age children with inadequate or delayed social-verbal communication skills; children are asked to formulate speech acts to go with pictured situational contexts.
lever arm dysfunction: A group of neuromuscular/orthopedic abnormalities that negatively affect the efficiency of flexible joints.
lethargy: State of decreased consciousness in which the individual can be readily aroused, but this aroused state can only be maintained with difficulty.
leukocytosis: A transient increase in the white blood count, usually associated with inflammation or infection.
leukodystrophy: See white matter disease.
leukomalada: Necrosis (tissue death) in the white matter of the brain, generally secondary to an anoxic (oxygen-deficiency) insult. In premature babies, this is most commonly located around the ventricles (fluid-containing spaces) and is termed periventricular leukomalada.
level: Any standard, position, or rank in a graded series of values, often as a measure of ability or performance. For example, levels of sensory efficiency, intellectual capacity, or motor development can he determined. Levels are relative and the cutoffs may be arbitrary.
lexicon: Dictionary; a collection of words, their meanings, and associated information.
Lexington Developmental Scales (Short Form): A developmental screening test for children from birth to 6 years of age. The instrument assesses motor, personal-social, cognitive-preacademic, language, and articulation areas by a variety of measures over an administration time of approximately 35 minutes. Standardization remains limited.
LGA: See large for gestational age.
Licensed Clinical Social Worker (L.C.S.W.): A person legally sanctioned by state statute to practice clinical social work. Licensing implies meeting minimum standards, which may or may not include academic or professional training and competency-based testing. When seeking a fully qualified social worker, the client should inquire about both licensing and Academy of Certified Social Workers certification.
licensing: A state-legislated and state-maintained competency-based sanction for professional practice. License laws restrict those able to perform certain tasks and duties by virtue of both education and tested competency levels. Thus, a medical doctor may not apply for a license to practice medicine without furnishing documentation of specific competencies and educational attainment. Other professions, such as social work, psychology, speech and language specialties, and nursing, must be similarly licensed. When a profession is regulated by licensing, it is illegal to perform those services without a license.
Light Retention Scale: A measure developed by educational psychologist H. Wayne Light; it is used by some school districts to help determine whether a child should be retained in the same grade. Although not a psychometric instrument, the retention scale consists of 19 factors from which a child receives a score categorizing him or her as being a fair (score of 32-40), good (score of 10-31), or excellent (score of 0-9) candidate for retention. The factors used to make this determination include age, grade, sex, previous retention, intelligence level, and evidence of learning disabilities. On this scale, boys make better retention candidates than girls, as do children who are small for their age and/or young for their grade. A number of the factors used by Light to determine appropriateness for retention are unsupported by research; rather, they are criteria informally established by teachers over the years as a basis for holding back children.
Likert scale: A scaling technique in which the subject indicates his or her degree of (dis)agreement with a variety of attitudinal statements, usually on a 3- or 5-point scale.
limb synergy: A group of muscles acting as a bound unit (all flexing or all extending) in a primitive and stereotyped manner.
limbic system: A group of functionally related brain structures that regulate emotions and primary drives.
Lincoln-Oseretsky Motor Development Scale: A measure of motor dexterity (balance, speed, dexterity, rhythm, and coordination) for children between 6 and 14 years of age.
Lindamood Auditory Conceptualization Test (LAC): A 10-minute criterion-referenced test for preschool children to adults that measures auditory discrimination and perception of number and order of speech sounds in sequences.
linguistic reader: An instructional model that does not emphasize meaning in beginning reading but, rather, stresses mastery of a limited number of consistent spelling patterns that correspond to syllables heard in oral language. Words are read as wholes, not sounded out letter by letter. Linguistic readers frequently have few pictures to avoid distracting the beginning reader.
linguistics: The scientific study of the origin, structure, nature, and function of language.
linkage: The coinheritance of two or more traits at a rate greater than one would expect by chance because they are present side by side on the same chromosome. In some families, males are affected with more than one X-linked disorder because the X chromosomes they received had the disease gene for Duchenne muscular dystrophy, chronic granulomatous disease, and retinitis pigmentosa (night blindness and progressively restricted visual field). This linkage helps in the identification of the gene locations for each disorder.
lipidoses: A group of progressive neurological disorders characterized by defects in lipid metabolism. Histochemically, the neurons (nerve cells) are filled with lipids (fats). The actual biochemical defects of these disorders are unknown.
lipreading: See speech reading.
LIPS: See Leiter International Performance Scale.
lissencephaly: Agyria—literally, "smooth brain"; a condition in which there is abnormal migration of neurons (nerve cells) during early fetal life, resulting in lack of gyri (hills). This is often associated with other abnormalities such as heterotopia (displacement of an organ or tissue), pachygyria (broad, flat cerebral convolutions), or micropolygyna (an increased number of smaller ridgings on the brain surface). Clinically, these individuals have severe mental retardation and marked hypotonia (decreased muscle tone). Seizures, including infantile spasms and Lennox-Gastaut syndrome, are common. A small number of children with lissencephaly have an accompanying chromosomal abnormality or a known genetic syndrome (e.g., Miller-Dieker syndrome). Infection with cytomegalovirus (CMV) has also been described. Lissencephaly can be detected on a computed tomography (C-T) scan. Both lissencephaly and Miller-Dieker syndrome are associated with deletions on chromosome l7-p13.
lithium: An antipsychotic drug that can be used to treat severe behavior disorders in people with developmental disorders. It is believed to normalize receptor site sensitivity in the brain to reduce mood swings. Side effects include drowsiness, tremors, and electrocardiogram (ECG) changes. Blood levels must be carefully monitored for toxicity.
litmus test: A test that indicates a solution's degree of acidity or alkalinity. Litmus is a chemical substance (usually in the form of a chemically impregnated paper strip—litmus paper) that turns red in an acid solution and blue in an alkali, or basic, solution. Metaphorically, a litmus test suggests that classification can be successfully achieved using a single parameter—for example, IQ to define mental retardation; such usage often reflects an oversimplification.
Little disease: An old term for cerebral palsy in general or spastic diplegia (paralysis on both sides of the body) in particular; eponym after William John Little (1810-1894), who first described cerebral palsy.
Little etiology: Old term for perinatal asphyxia (lack of oxygen) as a cause of brain damage leading to later cerebral palsy, mental retardation, or other chronic, central nervous system impairment. Perinatal asphyxia, especially as reflected in low Apgar scores, is no longer considered a significantly frequent cause of cerebral palsy. The contribution of perinatal asphyxia to otherwise unexplained mental retardation continues to be debated.
LMP: See last menstrual period.
LNNB-CR: See Luria-Nebraska Neuropsychological Battery-Children's Revision.
loading: A statistical term referring to the correlations between factors and tests in factor matrix. Loadings indicate the weight of each factor in determining performance on each; see also factor analysis.
locomotion in prone: Movement from one point to another with the body horizontal and the chest and abdomen not raised off the ground; movement is accomplished by coordinated and sometimes alternating pulling with the arms and pushing with the legs. Sometimes a synonym for creeping.
locomotion in quadruped: Movement from one point to another with the body horizontal and chest and abdomen raised off the floor so the child is supported on elbows/hands and knees/feet; movement is accomplished by coordinated and alternating actions of all four extremities (arms and legs). Sometimes a synonym for crawling. The child who walks before he or she crawls is not necessarily at increased risk for developmental disabilities.
locus of control: A theory explaining a person's view of most causal mechanisms for feelings, successes, failures, or behavioral outcomes. Two loci of control are postulated: external and internal. People tend to base most of their causal explanations on either an external cause (e.g., it was God's will) or an internal cause (e.g., I really did a good job). Many educational and psychological interventions arc based on a framework using a person's predominant locus of control attribution.
long leg brace: A brace that extends from the upper thigh to the foot.
long-term care: A coordinated set of health, social, personal, and protective services, usually in an out-of-home placement. The underlying assumption or connotation of this term is long-term, severe, irremediable impairment (physical or cognitive). Some people with developmental disabilities need long-term care of some form (e.g., group homes, sheltered workshops).
long-term memory: The component of conceptual models of memory in which information is stored for later use. In contrast to short-term, or working, memory, long-term memory has a very large capacity, and, although unproven, information stored there may last a lifetime. Often the feeling of not remembering is related to the inability to retrieve the information. This phenomenon is often seen in children with learning disabilities, particularly for specific information on demand. Information retained for 1 or 2 minutes is retained in the same manner as that retained after 1 or 2 days and is assumed to be encoded in long-term memory. Memory theorists have conceptually divided long-term memory into semantic (meaning systems) memory, episodic memory, and procedural memory. See also memory.
lorazepam: Trade name Ativan; a drug in the class of benzodiazepines (the most widely known of which is diazepam [Valium], used to treat seizures. Lorazepam is a rapidly acting drug that is quite successful in the treatment of status epilepticus. The advantage of using lorazepam over diazepam is that it continues to suppress seizure activity for 24-48 hours after administration, and it does not produce as much respiratory depression. Lorazepam also has an antianxiety effect and can be used chronically to decrease anxiety.
lordosis: An excessive curvature of the lower vertebral column (spine), convex anteriorly, to produce a swayback appearance.
Louis-Bar syndrome: See ataxia telangiectasia.
low birth weight (LBW): Describes an infant whose birth weight is less than 2,500 grams, regardless of gestational age (full-term or premature).
low-set ear: See pinna.
low-vision: Generally refers to a severe visual impairment, not necessarily limited to distance vision. Low vision applies to all individuals who are unable to read the newspaper at a normal viewing distance, even with the aid of corrective lenses.
Lowe syndrome: Oculocerebrorenal syndrome; a genetic syndrome with hypotonia (decreased muscle tone), cataracts, kidney disease, and severe mental retardation. Inheritance is X-linked.
lower esophageal sphincter: (LES) The pressure difference between the lower part of the esophagus and the stomach; lowering of this gradient can contribute to gastroesophageal reflux.
lower extremity: Thigh, leg, and foot.
LPAD: See Learning Potential Assessment Device.
LPT: See Language Processing Test.
LRE: See least restrictive environment.
LSI: See Learning-Style Inventory.
LTI-A: See Let's Talk Inventory for Adolescents.
LTI-C: See Let's Talk Inventory for Children.
lumbar: Relating to that part of the back between the ribs and the hips.
lumbar puncture: See spinal tap.
lumping: The tendency to classify together entities that at first do not appear to go together.
Luque rod: An orthopedic surgery procedure to treat scoliosis (spinal curvature) by wiring each of the vertebrae to a metal rod; sometimes combined with a Harrington rod.
Luria, Alexander Romanovich: (1902-1977) A Russian physician and neuropsychologist whose work with World War II brain injuries laid the foundation for modern neuropsychology and brain localization tests.
Luria-Nebraska Neuropsychological Battery-Children's Revision (LNNB-CR): A neuropsychological battery for children 8-12 years of age.
lymphadenopathy: Swelling of the lymph nodes that produces palpable masses and sometimes tenderness; it is often a sign of infection but may be associated with other causes of inflammation. When an infection is localized, the lymph nodes nearest the site of the infection are usually more involved. For example, cervical (neck) lymphadenopathy frequently accompanies tonsillitis or pharyngitis (throat infection/inflammation). Lymph nodes may remain swollen or palpable for some time after an infection has resolved.