Language Development and Communication Disorders

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Chapter 32 Language Development and Communication Disorders

Mark D. Simms, Robert L. Schum

Normal Language Development

For most children, learning to communicate in their native language is a naturally acquired skill whose potential is present at birth. No specific instruction is required, although children must be exposed to a language-rich environment. Normal development of speech and language is predicated on the infant’s ability to hear, see, comprehend, and remember. Equally important are sufficient motor skills to imitate oral motor movements, and the social ability to interact with others.

For the purposes of analysis, language is subdivided into several essential components. Communication consists of a wide range of behaviors and skills. At the level of basic verbal ability, phonology refers the correct use of speech sounds to form words, semantics refers to the correct use of words, and syntax refers to the appropriate use of grammar to make sentences. At a more abstract level, verbal skills include the ability to link thoughts together in a coherent fashion and to maintain a topic of conversation. Pragmatic abilities include verbal and nonverbal skills that facilitate the exchange of ideas, including the appropriate choice of language for the situation and circumstance and the appropriate use of body language (i.e., posture, eye contact, gestures). Social pragmatic and behavioral skills also play an important role in effective interactions with communication partners (i.e., engaging, responding, and maintaining reciprocal exchanges).

It is customary to divide language skills into receptive (hearing and understanding) and expressive (talking) abilities. Language development usually follows a fairly predictable pattern and parallels general intellectual development (Table 32-1).

Table 32-1 NORMAL LANGUAGE MILESTONES

HEARING AND UNDERSTANDING TALKING
BIRTH TO 3 MONTHS
Startles to loud sounds
Quiets or smiles when spoken to
Seems to recognize your voice and quiets if crying
Increases or decreases sucking behavior in response to sound

Makes pleasure sounds (cooing, gooing)
Cries differently for different needs
Smiles when sees you
4 TO 6 MONTHS
Moves eyes in direction of sounds
Responds to changes in tone of your voice
Notices toys that make sounds
Pays attention to music
Babbling sounds more speech-like, with many different sounds, including p, b, and m
Vocalizes excitement and displeasure
Makes gurgling sounds when left alone and when playing with you
7 MONTHS TO 1 YEAR
Enjoys games such as peekaboo and pat-a-cake
Turns and looks in direction of sounds
Listens when spoken to
Recognizes words for common items, such as cup, shoe, and juice
Begins to respond to requests (Come here. Want more?)
Babbling has both long and short groups of sounds, such as tata upup bibibibi.
Uses speech or noncrying sounds to get and keep attention
Imitates different speech sounds
Has 1 or 2 words (bye-bye, Dada, Mama), although they might not be clear
1 TO 2 YEARS
Points to a few body parts when asked
Follows simple commands and understands simple questions (Roll the ball. Kiss the baby. Where’s your shoe?)
Listens to simple stories, songs, and rhymes
Points to pictures in a book when named
Says more words every month
Uses some 1-2 word questions (Where kitty? Go bye-bye? What’s that?)
Puts 2 words together (more cookie, no juice, mommy book)
Uses many different consonant sounds at the beginning of words
2 TO 3 YEARS
Understands differences in meaning (e.g., go-stop, in-on, big-little, up-down)
Follows 2-step requests (Get the book and put it on the table.)
Has a word for almost everything
Uses 2-3 word “sentences” to talk about and ask for things
Speech is understood by familiar listeners most of the time
Often asks for or directs attention to objects by naming them
3 TO 4 YEARS
Hears you when you call from another room
Hears television or radio at the same loudness level as other family members
Understands simple who, what, where, why questions
Talks about activities at school or at friends’ homes
Usually understood by people outside the family
Uses a lot of sentences that have ≥4 words
Usually talks easily without repeating syllables or words
4 TO 5 YEARS
Pays attention to a short story and answers simple questions about it
Hears and understands most of what is said at home and in school
Voice sounds as clear as other children’s
Uses sentences that include details (I like to read my books.)
Tells stories that stick to a topic
Communicates easily with other children and adults
Says most sounds correctly except a few, such as l, s, r, v, z, ch, sh, and th
Uses the same grammar as the rest of the family

From American Speech-Language-Hearing Association, 2005. http://professional.asha.org.

Receptive Language Development

From birth, newborns demonstrate preferential response to human voices over inanimate sounds. The infant alerts and turns toward the direction of an adult who speaks in a soft, high-pitched voice. Over the first 3 mo, infants appear to recognize their parent’s voice and quiet if crying. Between 4 and 6 mo, infants visually search for the source of sounds, again showing a preference for the human voice over other environmental sounds. By 5 mo, infants can passively follow the adult’s line of visual regard, resulting in a “joint reference” to the same objects and events in the environment. The ability to share the same experience is critical to the development of further language, social, and cognitive skills. By 8 mo, the infant can actively show, give, and point to objects. Comprehension of words often becomes apparent by 9 mo, when the infant selectively responds to his or her name and appears to comprehend the word “no.” Social games, such as “peek-a-boo,” “so big,” and waving “bye-bye” can be elicited by simply mentioning the words. At 12 mo, many children can follow a simple, one-step request without a gesture (e.g., “Give it to me!”).

Between 1 and 2 yr, comprehension of language accelerates rapidly. Toddlers can point to body parts on command, identify pictures in books when named, and respond to simple questions (e.g., “Where’s your shoe?”). The 2 yr old is able to follow a 2-step command, employing unrelated tasks (e.g., “Take off your shoes, then go sit at the table”), and can point to objects described by their use (e.g., “Give me the one we drink from”). By 3 yr, children typically understand simple “wh-” question forms (e.g., who, what, where, why). By 4 yr, most children can follow adult conversation. They can listen to a short story and answer simple questions about it. Five yr olds typically have a receptive vocabulary of over 2000 words and can follow 3- and 4-step commands.

Expressive Language Development

Cooing noises are established by 4 to 6 wk of age. Over the first 3 mo of life, parents may distinguish their infant’s different vocal sounds for pleasure, pain, fussing, tiredness, etc. Many 3 mo old infants vocalize in a reciprocal fashion with an adult to maintain a social interaction (“vocal tennis”). By 4 mo, infants begin to make bilabial (“raspberry”) sounds, and by 5 mo monosyllables and laughing are noticeable. Between 6 and 8 mo, polysyllabic babbling (“lalala” or “mamama”) is heard and the infant might begin to communicate with gestures. Between 8 and 10 mo, babbling makes a phonologic shift toward the particular sound patterns of the child’s native language (i.e., they produce more native sounds than nonnative sounds). At 9 to 10 mo, babbling becomes truncated into specific words (e.g., “mama,” or “dada”) for their parents.

Over the next several mo, infants learn 1 or 2 words for common objects and begin to imitate words presented by an adult. These words might appear to come and go from the child’s repertoire until a stable group of 10 or more words is established. The rate of acquisition of new words is approximately 1 new word per wk at 12 mo, but it accelerates to approximately 1 new word per day by 2 yr. The first words to appear are used primarily to label objects (nouns) or to ask for objects and people (requests). By 18 to 20 mo, toddlers should use a minimum of 20 words and produce jargon (strings of word-like sounds) with language-like inflection patterns (rising and falling speech patterns). This jargon usually contains some embedded true words. Spontaneous 2-word phrases (pivotal speech), consisting of the flexible juxtaposition of words with clear intention (e.g., “Want juice!” or “Me down!”), is characteristic of 2 yr olds and reflects the emergence of grammatical ability (syntax).

Two-word, combinational phrases do not usually emerge until the child has acquired 50-100 words in their lexicon. Thereafter, the acquisition of new words accelerates rapidly. As knowledge of grammar increases, there is a proportional increase in verbs, adjectives, and other words that serve to define the relation between objects and people (predicates). By 3 yr, sentence length increases and the child uses pronouns and simple present tense verb forms. These 3-5 word sentences typically have a subject and verb but lack conjunctions, articles, and complex verb forms. The Sesame Street character Cookie Monster (“Me want cookie!”) typifies the “telegraphic” nature of the 3 yr old’s sentences. By 4-5 yr, children should be able to carry on conversations using adult-like grammatical forms and use sentences that provide details (e.g., “I like to read my books”).

Variations of Normal

Language milestones have been found to be largely universal across languages and cultures, with some variations depending on the complexity of the grammatical structure of individual languages. In Italian (where verbs often occupy a prominent position at the beginning or end of sentences), 14 mo olds produce a greater proportion of verbs compared with English speaking infants. Within a given language, development usually follows a fairly predictable pattern, paralleling general cognitive development. Although the sequences are predictable, the exact timing of achievement is not. There are marked variations among normal children in the rate of development of babbling, comprehension of words, production of single words, and use of combinational forms within the first 2-3 yr of life.

Two basic patterns of language learning have been identified: “analytic” and “holistic.” The analytic pattern is the most common and reflects the mastery of increasingly larger units of language form. As reflected in the previous discussion of milestones, the child’s analytic skills proceed from simple to more complex and lengthy forms. Children who follow a holistic or gestalt learning pattern might start by using relatively large chunks of speech in familiar contexts. They might memorize familiar phrases or dialogs from movies or stories and repeat them in an over-generalized fashion. Their sentences often have a formulaic pattern, reflecting inadequate mastery of the use of grammar to flexibly and spontaneously combine words appropriately in the child’s own unique utterance. Over time, these children gradually break down the meanings of phrases and sentences into their component parts, and they learn to analyze the linguistic units of these memorized forms. As this occurs, more original speech productions emerge and the child is able to assemble thoughts in a more flexible manner. Both analytic and holistic learning processes are necessary for normal language development to occur.

Language and Communication Disorders

Epidemiology

Disorders of speech and language affect up to 8% of preschool-aged children. Nearly 20% of 2 yr olds are thought to have delayed onset of speech. By age 5 yr, 19% of children are identified as having a speech and language disorder (6.4% speech impairment, 4.6% both speech and language impairment, and 8% language impairment). Boys are nearly twice as likely to have an identified speech or language impairment as girls.

Etiology

Normal language ability is a complex function that is widely distributed across the brain through interconnected neural networks that are synchronized for specific activities. Early researchers in language disorders, noting what appeared to be clinical parallels between acquired aphasia in adults and childhood language disorders, expected to find similar lesions in the brains of affected children. For the most part, unilateral, focal lesions acquired in early life do not seem to have the same effects in children as in adults. Furthermore, risk factors for neurologic injury are absent in the vast majority of children with language impairment.

Genetic factors appear to play a major role in influencing how children learn to talk. Language disorders appear to cluster in families. A careful family history may identify current or past speech or language problems in up to 30% of 1st-degree relatives of proband children. Although children who are exposed to parents with language difficulty might be expected to experience poor language stimulation and inappropriate language modeling, studies of twins have shown the concordance rate for low language test score and/or a history of speech therapy to be approximately 50% in dizygotic pairs, rising to over 90% in monozygotic pairs. A number of potential gene loci have been identified, but no consistent genetic markers have been established.

The most plausible genetic mechanism involves a disruption in the timing of early prenatal neurodevelopmental events affecting migration of nerve cells from the germinal matrix to the cerebral cortex. Chromosomal lesions and point mutations of the FOXP2 gene and polymorphisms of the CNTNAP2 gene are associated with an uncommon but distinct speech and language disorder characterized by difficulties in learning and producing oral movement sequences (developmental verbal dyspraxia, childhood apraxia of speech). Affected children have a spectrum of impairment in expressive and receptive language as well as problems understanding grammar.

Pathogenesis

Language disorders are associated with a fundamental deficit in the brain’s capacity to process complex information rapidly. Simultaneous evaluation of words (semantics), sentences (syntax), prosody (tone of voice), and social cues can overtax the child’s ability to comprehend and respond appropriately in a verbal setting. Limitations in the amount of information that can be stored in verbal working memory can further limit the rate at which language information is processed. Electrophysiologic studies have shown abnormal latency in the early phase of auditory processing in children with language disorders. Neuroimaging studies have identified an array of anatomic abnormalities in regions of the brain that are central to language processing. MRI scans in children with specific language impairment (SLI) can reveal white matter lesions, white matter volume loss, ventricular enlargement, focal gray matter heterotopia within the right and left parietotemporal white matter, abnormal morphology of the inferior frontal gyrus, atypical patterns of asymmetry of language cortex, or increased thickness of the corpus callosum. Postmortem studies of children with language disorders have found evidence of atypical symmetry in the plana temporale and cortical dysplasia in the region of the sylvian fissure. Additionally, some researchers have identified a high incidence of paroxysmal EEG anomalies during sleep in children with SLI. Although these findings might represent a mild variant of the Landau-Kleffner syndrome (acquired verbal auditory agnosia), they likely represent an epiphenomenon in which paroxysmal activity is related to architectural dysplasia. In support of a genetic mechanism affecting cerebral development, a high rate of atypical perisylvian asymmetries has also been documented in the parents of children with SLI.

Clinical Manifestations

Primary disorders of speech and language development are often found in the absence of broader cognitive or motor dysfunction. Disorders of communication are the most common comorbid condition in persons with generalized cognitive disorders (intellectual disability or autism), structural anomalies of the organs of speech (velopharyngeal insufficiency from cleft palate), and neuromotor conditions affecting oral motor coordination (dysarthria from cerebral palsy or other neuromuscular disorders).

Classification

Each professional discipline has adopted a somewhat different classification system, based on cluster patterns of symptoms. One of the simplest classifications is the American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) (Table 32-2). This system recognizes 4 types of communication disorders: expressive language disorder, mixed receptive-expressive language disorder, phonological disorder, and stuttering. In clinical practice, childhood speech and language disorders occur as a number of distinct entities.

Table 32-2 DSM-IV DIAGNOSTIC CRITERIA FOR COMMUNICATION DISORDERS

EXPRESSIVE LANGUAGE DISORDER

A The scores obtained from standardized individually administered measures of expressive language development are substantially below those obtained from standardized measures of both nonverbal intellectual capacity and receptive language development. The disturbance may be manifest clinically by symptoms that include having a markedly limited vocabulary, making errors in tense, or having difficulty recalling words or producing sentences with developmentally appropriate length or complexity
B The difficulties with expressive language interfere with academic or occupational achievement or with social communication
C Criteria are not met for mixed receptive-expressive language disorder or a pervasive developmental disorder
D If mental retardation, a speech-motor or sensory deficit, or environmental deprivation is present, the language difficulties are in excess of those usually associated with these problems

Coding note: If a speech-motor or sensory deficit or a neurologic condition is present, code the condition on Axis III

MIXED RECEPTIVE-EXPRESSIVE LANGUAGE DISORDER

A The scores obtained from a battery of standardized individually administered measures of both receptive and expressive language development are substantially below those obtained from standardized measures of nonverbal intellectual capacity. Symptoms include those for expressive language disorder as well as difficulty understanding words, sentences, or specific types of words, such as spatial terms
B The difficulties with receptive and expressive language significantly interfere with academic or occupational achievement or with social communication
C Criteria are not met for a pervasive developmental disorder
D If mental retardation, a speech-motor or sensory deficit, or environmental deprivation is present, the language difficulties are in excess of those usually associated with these problems

Coding note: If a speech-motor or sensory deficit or a neurologic condition is present, code the condition on Axis III

PHONOLOGICAL DISORDER

A Failure to use developmentally expected speech sounds that are appropriate for age and dialect (e.g., errors in sound production, use, representation, or organization such as, but not limited to, substitutions of 1 sound for another [use of /t/ for target /k/ sound] or omissions of sounds such as final consonants)
B The difficulties in speech sound production interfere with academic or occupational achievement or with social communication
C If mental retardation, a speech-motor or sensory deficit, or environmental deprivation is present, the speech difficulties are in excess of those usually associated with these problems

Coding note: If a speech-motor a sensory deficit or a neurologic condition is present, code the condition on Axis III

STUTTERING

A Disturbance in the normal fluency and time patterning of speech (inappropriate for the individual’s age), characterized by frequent occurrences of ≥1 of the following:

1 Sound and syllable repetitions
2 Sound prolongations
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