Prof. Dr. Nasir Sulman
Department of Special Education
University of Karachi
It has been said that all typically developing children in all cultures master the basics of their language by 4 years of age. However, 5% to 8% of children experience speech-language delays or disorders by the preschool years, which may be associated with later learning, socio-emotional, or behavioral problems. The primary clinician often is the first professional to whom parents turn when a developmental problem is suspected, and in the course of routine visits, the clinician may encounter any of the following language-related questions or concerns:
- The parents of a 9-month-old wonder what language and social skills should be present at this age, and they have heightened concern because an older sibling has autism.
- The parents of a 12-month-old wonder if their child is hearing impaired because he rarely responds to his name.
- The parents of an 18-month-old who has a history of recurrent ear infections ask if those infections will affect their child’s language development.
- A 20-month-old is reported to have lost the words he was using previously.
- The mother of the 2-year-old reports that her child is not talking as much as her older siblings did at the same age.
- The parents of a 3-year-old report that their child’s speech is very hard to understand and they wonder if this is normal.
- The father of a 3½-year-old expresses concern that his child has started stuttering.
Normal Language Development
Table 1 summarizes language milestones from birth to school age. From the neonatal period, children show interest in human voices and faces in preference to other stimuli, preferences that forge the building blocks of communicative development. By about 2 to 3 months of age, an infant begins to use his or her voice to make melodic vowel sounds called cooing. Shortly thereafter, they begin to enter into reciprocal vocal exchanges with their caregivers. By about 6 months of age, the child adds consonants to vowels, creating syllables known as babble. Also at about 6 months of age, children show emerging abilities to understand elements of the sound stream, responding appropriately to their name and to the word “no.” By 8 to 10 months of age, children can use verbal cues for practiced routines, such as “wave bye-bye.” Expressive communication at that age includes ma-ma or da-da, first used nonspecifically and then for the parent. Children begin to communicate nonverbally by pointing.
|Table 1: Normal Milestones in the Development of Language and Speech|
|Age||Receptive Skills||Expressive Skills|
|Birth||– Turns to source of sound
|– Shows preference for voices
– Shows interest in faces
Takes turns cooing
|6 months||Responds to name||Babbles|
|9 months||Understands verbal routines (wave bye-bye)||Points|
|12 months||Follows a verbal command||Uses jargon|
|15 months||Points to body parts by name||Learns words slowly|
|18 to 24 months||Understands sentences||Learns words quickly
Uses two-word phrases
|24 to 36 months||Answers questions||Phrases 50% intelligible
Builds three- (or more) word sentences
Asks “what” questions
|36 to 48 months||Understands much of what is said||Asks “why” questions
Sentences 75% intelligible
Masters the early acquired speech sounds: m, b, y, n, w, d, p, and h
|48 to 60 months||Understands much of what is said, commensurate with cognitive level||Creates well-formed sentences
Tells stories 100% intelligible
|6 years||Pronounces most speech sounds correctly; may have difficulty with sh, th as in think, s, z, th as in the, l, r, and the s in treasure|
|7 years||Pronounces speech sounds correctly, including consonant blends such as sp, tr, bl|
Detection of Language Delay
Table 2 describes abnormal findings on case history (or developmental observation) at various ages that should prompt further evaluation of a child’s language or speech. In addition, a delay of 25% or greater by 16 to 24 months of age is considered significant. For example, a 24-month-old child who functions as a typical 18-month-old can be considered to have a clinically significant language delay.
Speech and language delay in children is associated with increased difficulty with reading, writing, attention, and socialization. Although physicians should be alert to parental concerns and to whether children are meeting expected developmental milestones, there currently is insufficient evidence to recommend for or against routine use of formal screening instruments in primary care to detect speech and language delay. In children not meeting the expected milestones for speech and language, a comprehensive developmental evaluation is essential, because atypical language development can be a secondary characteristic of other physical and developmental problems that may first manifest as language problems. Types of primary speech and language delay include developmental speech and language delay, expressive language disorder, and receptive language disorder. Secondary speech and language delays are attributable to another condition such as hearing loss, intellectual disability, autism spectrum disorder, physical speech problems, or selective mutism. When speech and language delay is suspected, the primary care physician should discuss this concern with the parents and recommend referral to a speech-language pathologist and an audiologist. There is good evidence that speech-language therapy is helpful, particularly for children with expressive language disorder.
|Table 2: Indications for Referral for Delays and Disorders
of Language and Speech
|Birth and at any age||Lack of response to sound
Lack of interest in interaction with people
|4 months||Lack of any drive to communicate|
|6 to 9 months||Loss of the early ability to coo or babble
Poor sound localization or lack of responsiveness
|12 months||No verbal routines
Failure to use ma-ma or da-da
Loss of previous language or social milestones
|15 to 18 months||No single words
Poor understanding of language
|24 months||Vocabulary less than 50 words
No two-word phrases
Less than 50% of speech intelligible to strangers
|36 months||Rote memorization of words or phrases
Frequent immediate or delayed repetition of others’ speech
Flat or stilted intonation
More than 75% of speech unintelligible to strangers
|48 months||Inability to participate in conversation
Stuttering of initial sounds or parts of words
|6 to 7 years||Immature or inaccurate speech sound production|
Delayed Versus Disordered Language Development
Determining whether a developmental difference is significant and warrants further evaluation and intervention is one of the clinician’s greatest challenges. There is no generally agreed-upon standard for what constitutes a developmental language delay, and clinicians should consider data from multiple sources (history, screening tools, and clinical judgment) in determining which children are delayed or at risk. Parental concern should be acknowledged and is, in itself, sufficient reason for closer examination of the child’s status. Parental worry about language status in the toddler and preschool-age child has been associated with delayed expressive language development.
The term “language disorder” refers to a deficit in the comprehension or production of language that causes clinically significant impairment in functioning relative to developmental norms and cultural expectations. A child who has a developmental language delay may or may not develop a speech-language disorder, depending on the severity of the delay and whether it causes significant impairment in functioning. The clinician may identify a child at risk or one who is presenting with delayed language development, but the speech-language clinician usually determines whether a delay is clinically significant or constitutes a disorder.
Prevalence studies suggest that 13% to 18% of 1½- to 3-year-old children present with late talking or expressive language delays. At 4 years, approximately 50% of late talkers still present with language difficulties. Current screening measures do not predict reliably persistent language delay versus maturational lag followed by recovery. Factors that have been associated with early delays in expressive language include family history of language delay, low socioeconomic status, and the richness of the language environment.
Of those who continue to manifest speech-language delays, many require specific intervention. Early intervention programs often set a percent delay standard to determine eligibility, which typically is 20% to 30% below chronologic age in one or more domains of development.
Specific Language Impairment
Specific language impairment (SLI) refers to a disorder of oral language acquisition in the absence of environmental deprivation, deficits in nonverbal cognitive ability, hearing loss, autism, or other identified neurologic conditions. Recent research suggests, however, that children in whom SLI is diagnosed often have other, more subtle, deficits in non-language areas of functioning relative to normal controls. Children who have SLI have difficulty understanding and using syntax and grammar, such as tense markings, plurals, and possessives. Problems comprehending and formulating responses to open-ended questions (eg, why, what, and how) compromise their ability to participate in sustained conversation. Many children who have SLI eventually have trouble comprehending what they read.
Although its cause is unknown, SLI is presumed to be a biologically based neurodevelopmental disorder. Early signs of SLI include late onset of first words and phrases, immature or delayed mastery of the rules of grammar, and short utterance length relative to peers. Symptoms of SLI usually present in the preschool years, and by kindergarten age, an estimated 7% of children have SLI. Interestingly, in a prevalence study, only 29% of the parents of kindergartners in whom SLI was diagnosed had ever been told that their child had a significant speech-language problem. The clinician’s role in early detection and timely referral is underscored by the significant morbidity associated with persistent speech-language disorders and the efficacy of appropriate treatment.
Causes of Language Delay
Significant delays in language development can result from either biologic or environmental causes. The differential diagnosis of language delays in children who have no specific findings on history, physical examination, or neurologic examination includes hearing loss, global developmental delay, autism, specific language impairment, and psychosocial deprivation. Hearing loss may be suspected based on the pattern of the child’s understanding and production. Speech sounds at the greatest risk for poor reception and production in the context of moderate sensorineural hearing loss are s, th, and f, which are high-frequency sounds that have low energy. Global developmental delay may be suspected on the basis of other delays in cognitive or motor skills. If such developmental findings persist into school age, the child may meet diagnostic criteria for mental retardation.
Autistic disorder should be suspected when language not only is delayed but also is deviant, that is, different in terms of vocabulary, grammar, or communicative pattern from the language of younger children. In autism, qualitative impairments in communication are accompanied by qualitative impairments in social interaction, such as a lack of eye-to-eye gaze and reciprocity, and by restrictive, repetitive, and stereotyped patterns of behaviors, interests, or activities. Some children who have autism develop language and speech skills, but these higher functioning children show characteristic impairments in the ability to initiate or sustain conversation, a reliance on stereotyped or repetitive language rather than truly novel constructions, and flat or stilted intonation patterns. Longitudinal follow-up of preschool-age children who have autistic features and do not meet diagnostic criteria for autism at that age often finds that they meet diagnostic criteria at school age, although some children improve over time.
Specific language impairment may be suspected when language skills are lower than other cognitive abilities. Specific language impairment may affect only expressive language or both receptive and expressive language. Characteristics of the language include delays or errors in the use of elements of the grammar that are infrequent or unaccented in speech, such as accurate understanding or production of the plural or past-tense. In some children, social aspects of communication are affected, making differentiation of these semantic-pragmatic language impairments from autism challenging.
Language delays also can result from a poor linguistic environment. Children who have suffered child abuse or severe deprivation typically have delayed language and speech. Under less extreme conditions, the size of children’s vocabulary and the maturity of their grammatic skills are associated with the quality and quantity of parental input. The slow language development of children from low socioeconomic groups has been attributed to the relatively impoverished linguistic environment of children raised in poverty. Programs that encourage reading to infants and toddlers may improve language skills in children by increasing the amount and diversity of language in their environment.
Language and speech disorders are prevalent in the school-age population, and early delays are even more prevalent in toddlers and preschoolers. The pediatric clinician plays a central role in the detection, evaluation, and management of children who have these delays and disorders. Initial and ongoing assessment of language and speech use specific screening tests or a comprehensive history. Parent report inventories can be used to validate parental concerns. Children who have genetic, chromosomal, or neurologic disorders require evaluation and treatment appropriate to the underlying condition. For children who have no obvious underlying disorder, prediction of who will progress rapidly from those who will develop disorders is inaccurate. At a minimum, the evaluation of children who have significant delays in language or speech should include a full audiologic assessment, a comprehensive interdisciplinary developmental assessment for children who have additional cognitive or social problems, or a speech-language evaluation for children who have no other issues. The management of language and speech disorders should follow the principles of chronic care management. Children who have language and speech disorders are at risk for the development of academic and psychiatric disorders and, therefore, require regular long-term follow-up.
Zaheer is a 2½-year-old boy and came for a routine health supervision visit. On a general developmental screening questionnaire, his mother reports that he is not yet talking. She has not been too concerned because the child’s father was a late talker. Although the boy has had several episodes of otitis media, she feels strongly that there is no question of hearing loss because he seems to understand what is said to him. Other domains of development are reported as age-appropriate. His physical examination results are normal, and he appears to be a socially engaging toddler. However, we have concerns about his apparent low frustration tolerance and tendency to throw tantrums.
This 2½-year-old boy clearly has delayed expressive language development that requires further evaluation. It is important to explain to his mother that his failure to talk cannot be assumed to be due to the history of familial late talking or otitis media. Although his mother is confident that her son’s hearing is normal, his delayed language suggests the need for formal audiologic evaluation. A speech-language evaluation should be conducted either through his local early intervention program or by an independent speech-language pathologist. The early intervention program will also conduct a full developmental evaluation to rule out other problems and to design an individualized family service plan. The clinician can help the family understand the problem, make appropriate referrals, advocate for services, and guide the caregivers in supporting language development in the home environment.