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

habilitation

The provision of medical, psychological, educational, and family services to children with disabilities, in order to maximize these children's vocational, mental, physical, and social abilities and to allow them to function as independently as possible. Although the term adult rehabilitation refers to the recovery of abilities lost, pediatric habilitation connotes the development of abilities not previously mastered. The importance of the distinction lies in the differences in instructional techniques and individual motivation dealing with an adult who may remember having achieved a particular goal in the past, compared to a child who has no such experience on which to rely.

habit spasm

See tic.

habituation

Decreased response to a repeated stimulus that is not due to sensory adaptation or fatigue. Increased or decreased habituation may occur in mental retardation and syndromes involving brain damage. Rapidity or failure of habituation is a component of many infant cognitive assessments.

habitus

The physical characteristics of a person that are indicative of constitutional tendencies, disposition to (or presence of) disease, or personality traits. Habitus can include facies, somatotype, gait, and other movement patterns. With dysmorphology (atypical features) and physical signs, habitus is one of the major components of visual diagnosis, an approach important in pediatrics because patients often cannot otherwise communicate their concerns.

Haemophilus [also Hemophilus] influenzae (Hib)

Also known as "H flu." A common cause of bacterial infections (e.g., otitis, pneumonia, meningitis [inflammation of the spinal cord and brain membranes]) in children under 5 years of age.

Haeussermann developmental evaluation

An approach to the psychoeducational and developmental evaluation of preschool children that utilizes techniques from an individualized assessment of children with cerebral palsy. Motor and sensory disabilities are bypassed in this nonstandardized clinical assessment; 41 test items tap five areas: physical functioning and sensory status, perceptual functioning, competence in learning for short-term retention, language competence, and cognitive functioning. This method represents a pioneering approach to an assessment for educational intervention purposes.

hair whorl

The spiral pattern generated by the hair follicles of the scalp. Variations on the single clockwise posterior (back) hair whorl are minor dysmorphic (atypical appearance) features; these include poorly defined, double, and counterclockwise versions.

Haldol

See haloperidol.

Hall facies

The disproportion of forehead to face seen in hydrocephalus (excess fluid in the brain). Marshall Hall (1790-1857) was an English physician who first described this hydrocephalic facies.

Hallermann-Streif syndrome

Hallermann-Streiff-François syndrome; oculomandibulodyscephaly (malformation of the face, especially the lower jawbone and eyes) with hypotrichosis (hair deficiency). A dysmorphic (atypical appearance) syndrome with oculo (eye) findings: microphthalmia (small eyes) and congenital cataracts; mandibulo (]aw) findings: small jaw producing a "double" cutaneous chin with central dimple or cleft and contributing to a parrot nose appearance; dyscephaly; brachycephaly with frontal and parietal bossing (swelling); and hypotrichosis: thin, fine, scant hair. About one in seven cases exhibits mental retardation. Inheritance pattern remains unclear.

hallux

Big toe.

haloperidol

Trade name Haldol; an antipsychotic neuroleptic (major tranquilizer) drug. A butyrophenone, used to treat Gilles de la Tourette syndrome and severe behavior problems in children; it can cause severe extrapyramidal symptoms.

Halstead-Reitan Neuropsychological Test Battery for Older Children

An adaptation of the Halstead-Reitan adult battery to children 9-14 years of age. The battery is composed of 45 subtests grouped under such categories as motor, sensory-perceptual, visual-spatial, alertness and concentration, memory, abstract reasoning and logical analysis, right-left differences, and dysphasia. The simultaneous administration of a Wechsler Intelligence Scale is required to interpret the results and to calculate the Neuropsychological Deficit Scale (NDS) score, a number that estimates the total battery's estimated misclassification of an individual as having brain damage.

hamstrings

The tendons of the calf muscles.

hand regard

A fairly transient behavior observed briefly in children in the first 6 months of life. The infant stares at or through his or her nearly immobile hands. There is little or no touching of the hands and a minimum of movement (mostly slow, stereotyped, and rotatory—alternating pronation and supination). When prolonged, prominent, or occurring at a later age, this behavior is deviant and mav reflect autism, profound deprivation, or mental retardation.

handedness

The tendency to use one hand in preference to the other for activities including writing, eating, and throwing. Predominant use of the left hand is called sinistrality, and of the right hand, dextrality. A tendency toward a right- or left-handed preference emerges late in the first year but is not usually fully dominant until close to 2 years of age. Strong hand preference prior to 1 year of age suggests motor impairment (e.g.. hemiplegia [paralysis of half the body]) of the other side of the body. Failure of handedness to appear by 2 years of age may reflect global cognitive delay (mental retardation), mild motor incoordination, a language disorder, or a learning disability.

handicap

A disadvantage for a given individual resulting from an impairment or disability that limits or prevents the fulfillment of a role that would otherwise he normal for the individual. The term handicap is concerned with the value attached to an individual's situation or experience when it departs from the norm. It is characterized by a discordance between the individual's performance or status and his or her personal expectations or the expectations of the group to which he or she belongs. Handicap thus represents the socialization of an impairment or disability and the consequences for an individual. The term handicap is often inaccurately used as a synonym for disability. People with or without disabilities may have a societal standard or condition imposed upon them. Except when citing laws or regulations, the term handicap should not be used to describe a disability.

Handicapped Children's Protection Act of 1986 (PL 99-372)

An amendment to the Education of the Handicapped Act to allow parents who prevail in due process administrative hearings or court actions to be reimbursed for reasonable attorney's fees and other costs of preparing for the proceeding concerning their child's right to a free appropriate public special education and related services.

haptic

Tactile; relating to touch.

Haptic Intelligence Scale for the Adult Blind (HISab)

An adaptation of the Wechsler Adult Intelligence Scale that may be used with adolescents who are blind.

hard neurological sign

A neurological finding that can be interpreted as physiological or pathological, relatively independently of the individual's age. Hard signs contribute to the localization of brain lesions.

hard of hearing

Degrees of hearing loss that may be significantly improved with amplification (hearing aid). Although there is reduced hearing activity and sensitivity of the ears to sound, the ability to communicate orally is generally maintained.

Harrington distraction rod

An orthopedic surgery procedure that implants a metal rod into the vertebral column to correct scoliosis (spinal curvature): sometimes combined with a Luque rod.

Hartford Scale of Clinical Indicators of Cerebral Dysfunction in Child Psychiatric Patients

A 30-item measure of cerebral dysfunction in children 2-17 years of age. The scale is divided into three sections: 1) symptoms and signs related to impulsivity or direct aggression, 2) symptoms and signs related to compensatory adjustments against impulsivity or aggression, and 3) items from the individual's early history. Items are rated present or absent on the basis of clinical interviews with the parents, child, and family, as well as medical or school records. The higher the score (more than 7 or 8 items present), the greater the likelihood that cerebral dysfunction is present in the child.

hatchet face

A profile produced by atrophy (wasting) of facial muscles; found in myotonic dystrophy.

Hawaii Early Learning Profile (HELP)

An assessment instrument for birth to 3 years of age that covers six developmental areas encompassing 650 skills: cognitive (with receptive language), expressive language, fine motor, gross motor, social, and self-help. A sequenced checklist can be used to select objectives. The assessment component is keyed to a variety of intervention curricula and approaches.

Hayes-Binet

A dated adaptation of the Stanford-Binet Intelligence Scale for people ages 2 years to adult who are blind.

head lag

Inability of the head to keep up with the trunk when the baby is pulled to sitting; some degree of head lag may be observed up to 4 months of age. A frequent finding in the presence of hypotonia (decreased muscle tone) and motor disorders associated with hypotonia. Most types of cerebral palsy include an early phase of hypotonia, even though they later exhibit hypertonia (increased muscle tone), so head lag may be observed even in children who are later diagnosed with spastic or rigid types of cerebral palsy.

head retraction

A physical sign in infancy that reflects 1) part of a tonic labyrinthine posture (extension of all four extremities [arms or legs]), 2) a respiratory disorder, or 3) part of a transient extensor posture observed in preterm infants.

Head Start

A national program providing enriched early childhood education for children of low-income families. Established in 1965, Head Start's goals include meeting the developmental and educational needs of young children and increasing the likelihood of later school success. The program also provides a range of additional services designed to help meet health, nutrition, and social needs. In 1972, Head Start legislation was amended to include children with disabilities; of the total Head Start enrollment, 10% is reserved for children with disabilities. The inclusion of children with developmental disabilities in Head Start programs emphasizes the need for screening, diagnosis, and individualized program planning. Better grades, fewer grade retentions, limited and more effective use of subsequent special education services, and greater likelihood of completing high school and continuing education are some of the reported positive effects of preschool participation. Most research has examined the impact of early childhood education on children at risk due to economic or educational disadvantage. More recent investigations of early intervention efforts with general populations of parents and young children have shown gains for these children and their families as well.

hearing aid

An electronic device that amplifies sound coming to the wearer's ear. The device consists of a microphone, amplifier, and receiver that can route sound for air conduction (to one or both middle ears) or for bone conduction (to the hone of the skull) to augment the amount of sound stimulating the eighth cranial nerve. Hearing aids amplify all sound or only those frequencies (pitches) that are lost (such as in high-frequency hearing loss). The components of the hearing aid can be placed in a variety of locations to enhance volume, improve directionality of sound, and balance sound between the ears.

hearing impairment

Loss of auditory ability ranging in degree from slight to profound. Hearing impairments are generally categorized as conductive (involving the middle and outer ear) or sensorineural (involving the inner ear or the auditory nerve). Hearing impairment can also be classified as congenital (existing at or dating from birth), prelingual (occurring before the development of speech and language skills), and postlingual (occurring after the development of speech and language skills).

hearing impairment degrees

The six categories used to identify the level of auditory loss: slight (15-25 decibels [dB]), mild (26-40 dB), moderate (41-55 dB), moderately severe (56-70 dB), severe (71-90 dB), and profound (more than 91 dB). Each category has its own characteristics and indicates the disability most likely to result from such a loss.

hearing loss

Any level of auditory impairment ranging from slight difficulty to profound inability to hear. See also hearing impairment degrees.

heart disease, cyanotic

Heart disease of a type to produce some peripheral cyanosis (blue color) of the fingernails or lips. When such heart disease is not associated with a syndrome that also involves the central nervous system, it does not necessarily affect development. Poor oxygenation leading to cyanosis can, however, slow motor development. In young children, the amount of energy expended combating hypotonia (decreased muscle tone) can lead to difficulty with breathing, which interferes with the quantity of expressive language. Motor-dependent infant tests tend to underestimate IQ in pre-operative cyanotic heart disease.

heart rate response audiometry (HRRA)

The use of changes in heart rate on electrocardiogram (EKG) to assess hearing thresholds.

heel cord

See Achilles tendon.

heel cord lengthening

See tendo Achilles lengthening (TAL).

HEENT

An acronym for head, eyes, ears, nose, and throat; shorthand used in reporting findings on medical examination; an arbitrary grouping.

Helen Keller International

An organization founded in 1915 to assist governments and agencies in developing countries with the prevention and treatment of eye disease and with the education and rehabilitation of persons with visual impairment. The organization offers training for teachers and health care workers, with a focus on prevention of eye diseases. Volunteers are also instructed in counseling families of infants who are blind. Helen Keller International collects and compiles data on blindness throughout the world and publishes a newsletter, fact sheets, and other educational materials.

heliotrichous

Helical or spiral hair as found in the black populations.

helix

The shape of a spiral or coil, such as the ridges of the ear or the molecular structure of the gene.

HELP

See Hawaii Early Learning Profile.

hematocrit

The volume percentage of cells (solids) to whole blood (cells [solids] and plasma [liquid]). A low hematocrit is one indication of anemia.

hemianesthesia

Decreased to absent sensation on one side of the body; frequently accompanies hemianopsia (blindness for half the field of vision) and hemiatrophy (decreased growth and development on one side of the body) in hemiplegic cerebral palsy.

hemianopsia

Visual field cut; loss of vision for one half of the visual field. In a child with a left hemiplegic cerebral palsy, the motor control centers in the right brain are damaged. If that injury extends to the right occipital region, the child may have a cut in the left visual field and not perceive objects coming from the left side. The measurement of visual field (by perimetry) is difficult in young children, but the possibility of a hemianopsia should be suspected in cases of hemiplegic cerebral palsy with hemiatrophy (decreased growth and development on one side of the body) and hemianesthesia (decreased or absent sensation on one side of the body), especially if the child constantly tilts the head to one side. The degree of visual impairment is rarely significant, hut may need to be considered in selecting alternate communication devices such as communication boards.

hemiatrophy

Undergrowth of one side of the body. Although this can be associated with several rare syndromes (e.g., Russell-Silver syndrome), it is more typically found on the involved side in a hemiplegic cerebral palsy. The presence of this unilateral growth disturbance also acts as a marker for such associated deficits as hemianopsia (blindness for half the field of vision) and hemianesthesia (decreased or absent sensation on one side of the body).

hemiballismus

See ballismus.

hemihypertrophy

Enlargement of the limbs on one side of the body; can occur in a number of syndromes, such as Russell-Silver, Klippel-Trenaunay-Weber, Beckwith-Wiedemann, chondrodysplasia punctata, and Wilms' tumor (a malignancy of the kidney).

hemiplegia

Literally, "half palsy"; a topographical type of spastic cerebral palsy in which one side of the body (the arm more than the leg) is motorically involved, while the other is spared. The prognosis for independent ambulation is excellent. People with hemiplegia frequently have normal intelligence, learning disabilities, seizures, and hemiatrophy (decreased growth and development on one side of the body) and hemianesthesia (decreased or absent sensation on one side of the body) on the involved side. Hemianopsia (blindness for half the field of vision) can be present ipsilaterally to (on the same side as) the motor impairment. Seizure disorders are of such high frequency that they should be closely monitored for the first decade of life. Right hemiplegia is more common than left hemiplegia. Double hemiplegia refers to a quadriplegia in which both arms are more involved than both legs.

hemisphere

In reference to the brain, one of the two halves (right and left). The left hemisphere is responsible for the comprehension and production of language, whereas the right side controls nonverbal, spatial, and visual tasks. Damage to the left side of the brain may result in aphasia (loss of language skills) or a language problem.

hemisyndrome

Any asymmetry of movement, posture, or motor behavior. A hemisyndrome is present in hemiplegic cerebral palsy, but milder asymmetries may be associated with disorders of learning, behavior, and temperament.

hemorrhage

Bleeding; loss of blood.

hepatic

Relating to the hepar (liver).

hepatolenticular degeneration

See Wilson disease.

hepatosplenomegaly

Pathological enlargement of the liver and the spleen; a common finding in metabolic storage disorders such as mucopolysaccharidoses and Gaucher disease.

heredodegenerative diseases

A grouping of diseases that are familial and degenerative in nature. The degeneration is chronic and progressive, resulting in worsening function and often loss of function. These diseases are generally grouped by the area of the brain that is affected and thus determines the functional insult. This can occur in the basal ganglia, for example, causing gait disturbances, tremors, and rigidity without intellectual deterioration such as is found in juvenile paralysis agitans, or juvenile Parkinsonism. In other degenerative disorders, such as Hallervorden-Spatz syndrome, intellectual deterioration occurs with motor findings such as limb stiffness. Another example is Huntington chorea. The pattern of inheritance of these disorders varies. The underlying biochemical abnormalities are under investigation.

heritability

A statistical measurement of the degree to which a trait is genetically determined. This is generally used to determine the amount of impact the genes have as compared to environmental factors such as toxins (poisons).

Hermansky-Pudlak syndrome

A generic syndrome with partial albinism (contributing to reduced visual acuity) and a bleeding disorder. Inheritance is autosomal recessive.

hernia

Abnormal protrusion of part of an organ.

herniorrhaphy

The surgical repair (closing) of a hernia.

herpes simplex virus

A DNA (deoxyribonucleic acid) virus group that can produce herpetic skin lesions, meningoencephalitis, and a congenital infection syndrome. One of the sexually transmitted viruses, herpes simplex is to be distinguished from herpes zoster, the virus that causes "cold sores."

hertz

A unit of vibration; the frequency of one cycle per second (CPS), named after the German physicist, Heinrich R. Hertz (1857-1894).

heterochromia irides

Eyes of two different colors in the same individual; see also Waardenburg syndrome.

heterocyclic antidepressants

A class of drugs that includes tricyclic antidepressants, trazodone (trade name, Desyrel). and maprotiline (trade name, Ludiomil). These antidepressants are mood normalizers and are not habit forming.

heterodisomy

Isodisomy; a condition in which an individual receives two copies of a chromosome from one parent and none from the other. This can result in a loss of the effects of imprinting (the differences in chromosomes from different-sex parents) and can cause genetic disorders such as Prader-Willi syndrome.

heterogeneity

The situation in syndromology (the identification of genetic and other syndromes) when multiple genetic causes produce the same effect. The identification of separate genetic causes for the same phenotype (appearance) is the result of a process of "splitting." For instance, the phenotype Marfanoid habitus can he caused by Marfan syndrome, homocystinuria, and several other syndromes. Most malformation patterns, referred to as sequences, have multiple pathogenetic etiologies (causes).

heterogeneous grouping

In reference to an educational setting, placing students representing a range of characteristics (e.g., ability or age levels) together for instruction.

heterotopia

Islands of gray matter in the white matter of the brain. Found commonly with other abnormalities of neuronal (gray matter) migration, such as lissencephaly (smooth, rather than convoluted, brain surface) or micropolygyria (an increased number of smaller ridgings on the brain surface). Most migration abnormalities result in mental retardation, motor findings of spasticity or hypotonia (decreased muscle tone), and seizures. Heterotopia can be found in the brains of children with myelomeningocele (protuberance of both the spinal cord and its lining).

heterotopy

Sound displacement during speech, involving transposition and reversal of letters and phonemes; it is a characteristic of cluttered speech: example: "hip" for "flip."

heterozygote

An individual with different genes for the same trait.

heuristic

Rule or algorithm.

H flu

See Haemophilus influenzae.

HFV

See high-frequency ventilation.

HHE syndrome

Hemiplegia (paralysis of half the body), hemiconvulsion, and epilepsy syndrome with a characteristic frontotemporal spike—slow wave electroencephalographic (EEG) pattern; a complication of acute hemiplegia with febrile (feverish) illness.

HHHO syndrome

See Prader-Willi syndrome.

hiatal hernia

The protrusion of some part of the stomach above the diaphragm. This contributes to acid reflux and chest pain.

Hib

See Haemophilus influenzae.

HIE

See hypoxic-ischemic encephalopathy.

high arched palate

See palate.

high-frequency ventilation (HFV)

A type of mechanical ventilation that uses high rates (e.g., more than 900 breaths per minute) with very low tidal volumes. There are several variations of HFV.

hip abduction deformity

See frog posture.

hip adduction deformity

Positioning of the thigh closer to (or across) the mid-line. This deformity both leads to and results from hip dislocation or subluxation. Bilateral hip adduction deformity produces scissoring; this deformity is common in spastic cerebral palsy.

hip-knee-ankle-foot orthosis (HKAFO)

An orthosis that both supports and to some degree limits the entire lower extremity.

hippotherapy

Therapeutic horsemanship; the use of horseback riding as a treatment modality to enhance self-esteem and broaden experience in children with disabilities.

hippus

Rhythmic dilation (enlargement) and constriction of the pupils.

Hirschberg test

Corneal light reflex test; a screening test for strabismus (squint) in which the examiner shines a light and observes its reflection in the child's pupils. If the eyes are both straight, the reflection is at the same o'clock in each eye. An in-turned eye displaces the light laterally, whereas an out-turned eye displaces it medially.

Hirschsprung disease

Aganglionic megacolon, congenital megacolon; functional obstruction of the rectum or colon. A congenital absence of the nerve supply to the lower colon causes an absence of peristalsis (wavelike muscular contractions that propel food and waste along the gastrointestinal tract) that results in a massive enlargement of the colon, constipation, and obstruction. Treatment is in two stages: 1) a temporary colostomy, followed by 2) colonic resection of the involved segment. Infants with Down syndrome have an above-average (tenfold increased) incidence of Hirschsprung disease. Several other syndromes have an increased incidence of the disorder, and it is also associated with a variety of urogenital abnormalities. Named after the Danish pediatrician, Harold Hirschsprung (1830-1916).

hirsutism

A nonspecific condition of excessive facial or body hair. The cause may be familial, endocrine, pharmacological (e.g., after prolonged anticonvulsant usage), or genetic (part of a specific syndrome).

HISab

See Haptic Intelligence Scale for the Adult Blind.

Hiskey-Nebraska Test of Learning Aptitudes

An intelligence test for deaf children ages 3-16 years.

histidinemia

A disorder of amino acid metabolism with high blood levels of histidine; an autosomal recessive condition not associated with any disability. In the past, this disorder was considered an etiological factor in language disorders, but this association has been disproven.

HIV-1

See human immunodeficiency virus, type 1.

HKAFO

See hip-knee-ankle-foot orthosis.

HMD

Hyaline membrane disease. Seerespiratory distress syndrome.

hockey stick crease

A palmar crease variant in which the distal transverse crease abruptly exits between the second and third fingers.

Hoffmann sign

The stimulus of sudden extension of the middle finger whereby flicking or snapping the nail of that finger produces a flexion response of the thumb and index finger; a sign of pyramidal tract involvement.

holistic learning

An approach to learning in which variables are not broken down into their component parts but are examined in the context in which they occur. Rather than focusing on a specific and often arbitrary sequence of skills aimed at the remediation of impairments, proponents of the holistic approach advocate a language-rich environment wherein the fundamental purpose of language (reading, writing, speaking, and listening) is the communication of meaning. Teaching and learning are viewed as an interactive process, with the form of language seen as a tool to be refined in order to enhance meaning, rather than as a goal in itself. Proponents suggest that this is particularly beneficial to students with learning disabilities, whose cognitive variability often precludes a sequential approach to a task and whose conceptual skills are often tar ahead of their mechanical skills. Critics suggest that this approach does not sufficiently stress direct instruction in skills not readily assimilated by students with learning disabilities.

holistic medicine

Wholistic medicine; a vague catchword that indiscriminately connotes either or both of two attitudes toward traditional medicine: 1) a critique of scientific medicine as too exclusively focused on the disease, on technology, and on pathology (origin), rather than on the whole person, on health, or prevention; or 2) an espousal of a variety of naturopathic, shamanistic, homeopathic, vitamin and health food, and psychic and metaphysical regimens as self-help approaches to health (especially as part of "new age" mysticism). Because of the confusion often deliberately fostered by the term holistic, its usage should be abandoned, and whenever used, it should be considered suspect.

holophrastic speech

The use by young children of single words to express complete sentences. For example: "Cookie" for "I want a cookie," or "Out" for "Let me out of this stroller."

Holler Pudenz valve

A valve that allows unidirectional flow of cerebrospinal fluid in a shunt tube going from the brain to the atrium (heart) or peritoneum (abdomen) in the treatment of hydrocephalus (excess fluid in the brain).

HOME

See Home Observation for Measurement of the Environment.

home-based programs

Intervention that occurs in the child's home that focuses attention on the parent-child relationship and on the natural support systems of the family in order to strengthen family awareness of, and involvement with, the child. Services can be of many types, including those of a medical (physical/occupational therapy), educational (sensory and cognitive stimulation), and preventive (nutritional counseling, visiting nurse consultation) nature. In addition to the prescribed treatment, a goal of in-home intervention is to foster and maximize opportunities within the home to enhance intellectual, social, and emotional development. Home-based intervention is most often used with children from birth to 3 years of age.

home health

The provision of supportive medical services in the recipient's own home. Such services may include dressing care, feeding, intravenous (IV) care, physical therapy, respiratory therapy, nursing, dialysis, bathing, and other health-related services.

Home Observation for Measurement of the Environment (HOME)

An inventory of the home to quantitate the presence of toys, games, books, language stimulation, the physical environment, nurturance, academic goals, and modeling of social maturity and physical punishment as they relate to infants and preschoolers (one form for birth to 3 years of age, another for 3-6 years of age). The validity of this instrument is limited by the failure to include some measure of the impact of social desirability on the item answer/interpretation.

home school

In terms of disabilities, the element of inclusion that requires all students with disabilities to receive their education at the educational facility associated with their residence.

Home Screening Questionnaire (HSQ)

A component of the Denver Developmental Screening Test battery. A parent-answered instrument in two forms, blue for birth to 3 years of age, and white for 3-6 years of age.

homebound instruction

The provision of educational services for a student in his or her home due to illness, physical injury, or emotional condition. A child is eligible for homebound instruction, to be provided by a visiting or itinerant teacher, when school attendance is made impossible by the preceding conditions. Mandated by PL 101-476, the Individuals with Disabilities Education Act of 1990, homebound instruction is categorized as one of the most restrictive alternatives in a continuum of services, and is to be considered a temporary measure whenever possible.

homemaker services

Social or health services to support and help maintain persons with physical or cognitive disabilities in their own homes. Such services may include shopping, budgeting, cleaning, meal planning and preparation, in-home adaptive modifications, and assisting in communication or transportation with other agencies and services. The effort is to provide services in the homes of persons with disabilities, rather than moving them to long-term care facilities.

homeostasis

Tendency of biological and other systems to remain internally constant despite interacting with a changing external environment.

homocystinuria

A genetic inborn error of metabolism producing increased homocystine in the blood and urine. The habitus (physical appearance) is similar to that seen in Marfan syndrome, with a tall, thin stature, a malar (cheekbone) flush, and arachnodactyly (long, thin fingers and toes), except that the ectopia lentis (lens dislocation) is downward in homocystinuria and upward in Marfan syndrome. Osteoporosis (thinning of the hones), mental retardation (in 50% of cases), and a shuffling ("Charlie Chaplin") gait can be present. Inheritance is autosomal recessive, and the incidence is more common in people of Irish descent. The disorder can be responsive to pyridoxine (vitamin B₆) or a special diet.

homolateral limb synkinesis

A mutual dependency between the synergies of the affected upper and lower limbs, so that, for example, arm flexion evokes leg flexion.

hospitalism

A behavioral syndrome characterized by delays in mental and physical development, apathy, and waxy immobility that occurs when an infant is separated from the mother or primary caregiver. If the situation is prolonged (institutionalization) or includes frequent and recurrent infections, cachexia (general weight loss) and death may occur. To a milder degree, some form of hospitalism is common in infants and young children admitted to the hospital. Although the effects can be ameliorated by parental rooming-in and other techniques, hospitals are not appropriate settings for the cognitive and behavioral development of very young children.

House-Tree-Person Test

A projective test that requires children 5 years of age and older to draw and then interpret a house, a tree, and a person (in that order).

HRRA

See heart rate response audiometry.

HSQ

See Home Screening Questionnaire.

human immunodeficiency virus, type 1 (HIV-1)

The human retrovirus (a class of RNA viruses) that causes acquired immunodeficiency syndrome.

humerus

Upper arm bone.

humoral theory/humorism

A doctrine of the pathology (origin) and treatment of disease that originated in ancient Greece and influenced medical thinking in the 19th century. The four humors—blood, phlegm, black bile, and yellow bile—correlated with the four elements of ancient cosmology. Many traces of this ancient dogma persist both in language and in scientific popularization and misinterpretation of modern medical ideas about body chemistry, endocrinology, allergy, and immunology.

Hunter syndrome

Mucopolysaccharidosis (MPS) II, a genetic syndrome with growth deficiency, coarse facies, stiff joints, and hepatosplenomegaly (enlargement of the liver and spleen). In contrast to Hurler syndrome (MPS IH), MPS II has a more gradual onset with clear corneas. Mental retardation is variable; hearing loss occurs in half the cases. In contrast to all the other types of MPS, Hunter syndrome is X-linked, so there are no affected females. Named after the Canadian physician, Charles Hunter (1873-1955).

Huntington disease

Huntington chorea; adult onset hereditary neurodegenerative disease that affects the basal ganglia of the central nervous system and progresses to dementia. There is a rare juvenile onset rigid subtype. Inheritance is autosomal dominant with an incidence of 1 in 18,000. This disorder is one of the classic models for research into the underlying neuropathology of extrapyramidal movement disorders. Named after the American physician, George S. Huntington (1850-1916).

Hurler syndrome

Pfaundler-Hurler syndrome; mucopolysaccharidosis (MPS) IH. A genetic syndrome with growth deficiency, coarse facies, stiff joints, hepatosplenomegaly (enlargement of the liver and spleen), mental deficiency, and cloudy corneas. Named after the German pediatrician, Gertrud Hurler (1889-1965).

Hurler-Scheie compound syndrome

Mucopolysaccharidosis (MPS) 1H/S. A genetic syndrome with symptoms, progression, and severity intermediate between Hurler (MPS 1H) and Scheie (MPS 1S). Recurrence risk is 25%.

hyaline membrane disease (HMD)

See respiratory distress syndrome.

hydranencephaly

A condition in which the cerebral hemispheres are sacs made of glial (cell and fiber) tissue and filled with cerebrospinal fluid (CSF). Some islands of cortex are preserved, as are the brain stem, midbrain, and diencephalon. Four causes are postulated: 1) gestational insults such as intrauterine infection; 2) genetic abnormality of vessel formation; 3) defects in brain formation (e.g., embryogenesis, cell migration); and 4) the end point of a massive hydrocephalus (excess fluid in the brain) that runs its course in utero. Clinically, babies may have a normal to large head with normal infant reflexes. However, these infantile reflexes persist, and no normal development occurs, leading to a picture of cerebral palsy with spastic quadriparesis (weakness of all four extremities), seizures, and profound mental retardation. Diagnosis can be made by transillumination or imaging studies, such as computed tomography (CT) scan, magnetic resonance imaging (MRI), or ultrasound. There is no treatment.

hydrocephalus

"Water on the brain" or, more accurately, "water in the brain." A condition in which there is an enlargement of the ventricular system in the brain due to an increase in the amount of cerebrospinal fluid (CSF) present in the ventricles fluid-containing spaces) at one time. It may he caused by decreased absorption or increased production of CSF. Hydrocephalus may be congenital or acquired. Hydrocephalus is divided anatomically into two categories: 1) obstructive, and 2) communicating. Obstructive hydrocephalus is caused by a blockage of the circulation of CSF by a tumor, an anatomical narrowing of the ventricle (e.g., aqueductal stenosis), or a bleeding underneath the dura (the outer layer of the brain). Communicating hydrocephalus occurs when the absorption of CSF from the ventricles is blocked. This occurs in the Arnold-Chiari malformation (commonly associated with myelomeningocele [protuberance of both the spinal cord and its lining]), after an infection such as meningitis (inflammation of the spinal cord and brain membranes) or a hemorrhage (bleeding) in the brain (see stroke and intraventricular hemorrhage). Hydrocephalus is commonly manifested by ataxia (unsteady gait) and spasticity affecting the legs more than the arms. Judgment and reasoning are typically affected, and speech is generally preserved. However, children with hydrocephalus tend to have more expressive than receptive language, resulting in a characteristic speech pattern with little content, often called cocktail party chatter. Children with hydrocephalus may also experience a decline in mental function, including language use, that may progress with the hydrocephalus. The correlation between intellectual functioning and degree of hydrocephalus is poor, so that many children who have extensive hydrocephalus have normal intelligence. Hydrocephalus ex vacuo presents with the appearance of hvdrocephalus (enlarged ventricles) secondary to atrophy (wasting) of brain tissue.

hygroma

Chronic subdural hematoma; bleeding into the space between the membranes covering the brain and leading to contusion, weakness, developmental delay, and paralysis.

hyperactivity

Spontaneous gross-motor activity that is excessive for age. Motor activity increases as age or mental age decreases and in the presence of a variety of medical (e.g., hyperthyroidism), psychological (e.g., anxiety), interactional (e.g., maternal depression), and neurological (e.g., attention deficit disorder) conditions. Therefore, hyperactivity is not diagnostic of any particular entity but must be correlated with other findings. See also attention-deficit/hyperactivity disorder (ADHD).

hyperalimentation

Parenteral (intravenous) nutrition; feeding an individual by total parenteral alimentation (TPA) or total parenteral nutrition (TPN).

hyperammonemia, congenital

A group of metabolic disorders that present in infancy with vomiting, lethargy, and coma and progress to severe mental retardation or death; dietary treatment is available. There are five enzymatic subtypes: four are autosomal recessive, and one is X-linked. Incidence is 1 in 30,000, with a recurrence risk rate of 25% for the autosomal recessive subtypes and 50% for the X-linked subtype.

hyperbilirubinemia

A high level of bilirubin in the blood. Bilirubin is a red pigment produced in the body during the breakdown of hemoglobin (oxygen-carrying red blood cells); an excessive amount of bilirubin results from either too many red blood cells (e.g., polycythemia) or a deficit in hemoglobin breakdown (e.g., liver disease). The clinical presentation of hyperbilirubinemia is jaundice (yellowing of the skin). In infants, hyperbilirubinemia is treated with fluorescent lighting (bililight) and sometimes exchange transfusion to prevent the bile from damaging the basal ganglia of the brain and causing choreoathetoid cerebral palsy.

hyperexplexia, stiff baby syndrome

An autosomal dominant syndrome with hypertonia (increased muscle tone) at birth that becomes less pronounced with age. The baby maintains a fetal flexor habitus (appearance) with clenched fists and an anxious expression. The fact that the hypertonicity can be suddenly exaggerated by slight stimuli requires careful discrimination from a seizure disorder. Hyperexplexic babies have a high incidence of hernias and respiratory and gastromotility (movement of food and waste through the gastrointestinal tract) disorders but no cognitive impairment.

hyperkinesis

See hyperactivity.

hyperkinetic syndrome of childhood

A neurobehavioral syndrome with distractibility, short attention span, extreme overactivity, disinhibition, disorganization, occasional underactivity, impulsivity, marked mood fluctuation, and aggression. The preferred term for attention deficit/hyperactivity (ADHD) disorder in Europe and Great Britain. See attention-deficit/hyperactivity disorder.

hyperlexia

Advanced single-word reading skills that exceed grade levels of performance in other areas, as well as levels expected on the basis of intellectual ability. These word-calling skills arc high in the presence of poor reading comprehension. The term hyperlexia was first used in 1967, although the condition was described in the 1940s. There is no consensus concerning either the etiology (cause) or significance of the condition. Hyperlexia has been reported in populations of children with varying cognitive abilities, including some with severe mental retardation. Intellectual level by itself does not therefore seem to be a definitive factor in the condition. Hyperlexia is considered by some researchers to be a unique type of language disorder and a condition occurring with another reading disability. Others report that children with hyperlexia demonstrate a profile opposite from that shown by children with classic dyslexia on Wechsler performance subtests.

hypermetropia

See hyperopia.

hypernasality

A disorder of resonance secondary to velopharyngeal incompetence (structural or motor incoordination problems with the palate or velum).

hyperopia

Farsightedness—sees better at a distance; close vision not as good; also known as hypermetropia; corrected by plus diopter (convex) lenses. Hyperopia has been reported to be more common among children with learning disabilities and reading problems.

hyperplasia

An increase in the size of an organ through an increase in the number of cells.

hypertelorism

Increased distance between two paired organs. Ocular hypertelorism reflects an increased distance between the eyes (interpupillary distance); the diagnosis of an orbital hypertelorism requires that the measurement be made from a skull X ray. (Hypertelorism is, in practice, often equated with an increased inner canthal distance.) Hypertelorism is common in Down syndrome and in a number of other genetic disorders, hut is also a nonspecific dysmorphic (atypical) feature. As an isolated finding, it may be of no significance.

hypertonicity/hypertonia

Increased muscle tone; typically found in the spastic or rigid types of cerebral palsy. More generally, a neurological sign of pyramidal tract involvement.

hypertrichosis

Excessive hair; this can involve scalp, facial, eyebrow, eyelid, and body hair. Hypertrichosis can be genetic (familial or part of a specific syndrome), endocrinological (hormonal), or drug induced.

hypertrophy

An increase in the size of an organ through an increase in the size of the cells that comprise it.

hyperventilation

Rapid, deep breathing that mildly changes blood chemistries by decreasing the carbon dioxide (CO₂) level in the blood. Hyperventilation is used clinically to enhance or induce electroencephalogram (EEG) abnormalities, since it is known to precipitate seizures, especially the absence (petit mal) type. Hyperventilation is a routine part of the EEG evaluation in a child old enough to cooperate. Children ages 8-12 years generally show the most dramatic EEG; changes to hyperventilation, including diffuse slowing and sometimes abnormal wave complexes such as spike (a sharp pointed deviation) and slow waves (a rounded deviation). Hyperventilation can also be a symptom of a panic disorder or panic attack and can sometimes result in syncope (fainting).

hypocalcemia

Low blood calcium levels; acute symptoms include irritability, high-pitched cry, tremors, seizures, and tone abnormalities; chronic symptoms relate to delayed skeletal mineralization and rickets. Etiologies (causes) include metabolic disorders and deficient calcium or vitamin D intake. Transient hypocalcemia can produce symptoms in newborns with other medical problems.

hypochondriac

See somatization disorder.

hypoglossal nerve

The 12th cranial nerve; cranial nerve XII is responsible for movement of the tongue.

hypoglycemia

Low blood sugar; glucose is the principal substrate for brain oxidative metabolism; hypoglycemia may be asymptomatic (without symptoms), or it may produce a range of symptoms that include irritability, seizures, lethargy, fatigue, sweating, high-pitched cry, and coma. Severe prolonged hypoglycemia can produce brain damage leading to mental retardation. The hypothesis that transient, low-grade fluctuations in blood sugar, not documented by glucose tolerance testing, can contribute to disorders of attention and learning and can be treated by dietary intervention has no scientific support.

hypomania

Mild form of mania.

hypomelanosis of Ito

A genetic syndrome with streaky, patchy or spraylike depigmentation of the skin; seizures; mental retardation; and eye abnormalities.

hyponasality

A disorder of resonance that occurs with a stuffy nose, allergies, and enlarged adenoids. Hyponasality can affect speech clarity, as speech will sound muffled.

hyponatremia

Salt depletion; marked decrease in the concentration of sodium in the blood. A common cause of hyponatremia in small babies is the ingestion of overly dilute formula; the lowered sodium levels can produce convulsions.

hypospadias

A urological malformation in which the urethra opens on the underside of the penis instead of at the distal end. It can be found in different syndromes and may be associated with other urogenital anomalies (malformation, deformation, disruption, or dysplasia).

hypotelorism

Decreased distance between two paired organs. Ocular hypotelorism is a decreased distance between the eyes as reflected by a decreased interpupillary distance and usually a decreased inner canthal distance. It is often part of syndromes with mid-facial hypoplasia (defective tissue development).

hypothalamic midbrain dysregulation syndrome

Hypertension (high blood pressure), hyperthermia (fcver), hyperventilation (rapid breathing), and decerebration (generalized spasticity) occurring secondary to hypothalamic-mesencephalic dysfunction leading to a diencephalic—brain-stem disconnection syndrome or brain-stem release; this can occur during recovery from coma.

hypothyroidism, acquired

Decreased production of thyroid hormone after the newborn period with a variety of etiologies (causes), leading to a syndrome displaying many of the following features: decreased height growth, obesity, myxedema (dry swollen skin), goiter (neck swelling), cold intolerance, constipation, thin hair, lethargy, and sluggish deep-tendon reflexes.

hypothyroidism, congenital

Cretinism; a clinical syndrome caused by the absence or hypoplasia of the thyroid gland in newborn infants. Findings include prolonged jaundice (yellowing of the skin), feeding difficulties, sluggishness, somnolence (sleepiness), poor cry, and respiratory difficulties exacerbated by a large tongue. Cold mottled extremities (arms or legs), a large abdomen, and an umbilical hernia may also he present. A short thick neck, puffy face, and myxedema (dry swollen skin) develop. Stunting of physical growth and progressive mental retardation occur when diagnosis and treatment are delayed. Newborn thyroid screening is available.

hypotonic cerebral palsy

A physiological subtype of cerebral palsy characterized by severe low muscle tone and pronounced motor delay. Many cases of hypotonic cerebral palsy are transient: the early hypotonia eventually resolves into one of the other subtypes of cerebral palsy. Prolonged or permanent severe hypotonia (atonic cerebral palsy) is rare and is often associated with severe diffuse brain damage and profound mental retardation. Flaccid diplegia is an antiquated term for the transient hypotonia that precedes spastic cerebral palsy.

hypotonicity/hypotonia

Decreased muscle tone; floppiness, limpness, weakness. This is a frequent, if variable or intermittent, finding in extrapyramidal cerebral palsy. Floppy infant.

hypotrichosis

Decreased hair; this can include balding, alopecia (hair loss), and decreased eyelid, eyebrow, or body hair. Hypotrichosis can be genetic (familial or part of a specific syndrome), endocrine-logical (hormonal), or dermatological (skin) in cause.

hypoxic

Describing a low level of oxygen; this state can be due to low ambient oxygen or to respiratory, cardiac, or hematological (pertaining to the blood and blood-forming tissues) disorders.

hypoxic-ischemic encephalopathy (HIE)

Nonprogressive brain damage secondary to hypoxia (oxygen deficiency) and ischemia (blood supply deficiency); most perinatal asphyxia (lack of oxygen) occurs in utero.

hypsarhythmia

Infantile spasms.