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

Jacksonian march

A progression of a focal motor seizure that follows a particular pattern of spread to other body parts and finally becomes generalized. This is relatively rare and is often associated with an identifiable lesion in the cerebral cortex.

jargon

A body of specialized terms used by various subgroups of a society, especially among professionals in a given discipline. Meaningful communication is often hindered by the use of such jargon, particularly when individuals from several disciplines are discussing a given case or topic. This is because some words have different meanings according to the discipline in which they are used. When explaining developmental disabilities to parents, those with disabilities, or others, it is advisable to avoid using jargon entirely. These terms can sound contrived and assume an importance of their own, attributing a higher status to the individual using them. Providing information in a clear, direct, and thoughtful manner facilitates communication and the establishment of a cooperative relationship.

jargoning

Vocalization pattern of infants that has the intonation, inflection, and rhythm of conversational speech but is unintelligible; it sounds as though the baby is talking a foreign language. Immature jargoning is completely unintelligible, whereas mature jargoning contains one or more intelligible words mixed in with the gibberish. Jargoning as an expressive language milestone emerges between 14 months (immature) and 18 months (mature).

jaundice

A yellow tinge to the skin resulting from hyperbilirubinemia (high levels of bilirubin in the blood) secondary to diseases of the blood or liver. Physiological jaundice occurs in many normal new-horns with bilirubin levels up to 4 milligrams/deciliters in the first week of life. Physiological jaundice is due to a transient immaturity of the liver enzymes that help the body to remove bilirubin. In some breast fed babies, this jaundice may be prolonged and somewhat more severe. In older children, jaundice must he distinguished from carotenemia (yellowing of the skin due to excess carotene, rather than bilirubin, in the blood); with carotenemia, the whites of the eyes remain white. In adults, jaundice is most commonly associated with hepatitis.

jaw jerk

A sharp tap to the chin (stimulus) produces a reflex closure of the jaw (response).

Jekyll and Hyde personality

Dramatic and sudden emotional lability (changeability) in the absence of recognizable cause or precipitating factors; observed in children with attentional disorders and in Gilles de la Tourette syndrome. This term derived from Robert Louis Stevenson's (1850-1894) short story, The Strange Case of Dr. Jekyll and Mr. Hyde (1886), has also been used to describe the syndrome of repeated mental and physical deterioration and improvement observed in elderly people.

Jendrassik maneuver

An individual is asked to pull as hard as possible against hands hooked together by flexed fingers; this maneuver is utilized to enhance the knee jerk, in part by distracting the person's attention and decreasing anxiety over the examination of the lower extremities.

Jensen controversy

Unresolved debate instigated by the educational psychologist Arthur Jensen concerning the degree to which intelligence is hereditary and the implications that such estimates should have for educational programming. In this recent variation on the nature versus nurture controversy, most arguments have depended heavily on philosophical presuppositions or very refined statistical models. Except at the most abstract and theoretical level, this debate contributes nothing to conceptualizations of or approaches to mental retardation or learning disabilities.

Jervell and Lange-Nielsen syndrome

A genetic syndrome or profound congenital deafness associated with syncope (fainting) secondary to a heart conduction defect. Distinguishing this specific etiology (cause) for deafness is important, because drug treatment may prevent sudden death during a syncopal episode. Incidence is 1 in 1 million, with an autosomal recessive inheritance pattern.

jitteriness

Nonspecific irritability in infants; movements can be tremulous and sometimes jerky with clonus (rhythmic oscillations between flexion and extension); the absence of abnormal gaze or eye movements helps to distinguish jitteriness from neonatal seizures. The most common causes of jittery newborns in the past included asphyxia (lack of oxygen), hypocalcemia (low blood calcium), and hypoglycemia (low blood sugar levels); today the effects of drug withdrawal are rapidly becoming the primary etiology (cause).

Johanson-Blizzard syndrome

A genetic syndrome with deafness, hypothyroidism, a peculiar facies, growth deficiency, and frequent mental retardation. Inheritance is autosomal recessive.

Joubert syndrome

A genetic syndrome with episodic hyperpnea/apnea (disturbances of respiratory control), opsoclonus (abnormal eye movements), mental retardation, hypotonia (decreased muscle tonei. ataxia (an unsteady gait), and dysplasia (defective tissue development) of the cerebellum, resulting in partial or complete absence of the cerebellar vermis (central part of the brain) with other structural abnormalities of the brain, the routine association of this syndrome with severe mental retardation has been questioned; severe visual, motor, and articulation problems contribute to interpretive limitations on cognitive assessment. Inheritance follows an autosomal recessive pattern.

jug-handle ear

Protruding auricle. Rather than being a minor dysmorphic (atypical) feature, this tvpe of ear protrusion may reflect the presence of neuromuscular disease.

Jukes

Fictitious name for a real New York family that included more than 1,000 cases of mental deficiency; used as anecdotal support for the hypothesis that most mental retardation is hereditary. First reported in 1877 by R.L. Dugdale (1841-1883).