Speech is the motor act of communicating by articulating verbal expression, whereas language is the knowledge of a symbol system used for interpersonal communication.¹ In general, a child is considered to have speech delay if the child's speech development is significantly below the norm for children of the same age. A child with speech delay has speech development that is typical of a normally developing child of a younger chronologic age; the speech-delayed child's skills are acquired in a normal sequence, but at a slower-than-normal rate.²

Speech delay has long been a concern of physicians who care for children. The concern is well founded, because a number of developmental problems accompany delayed onset of speech. In addition, speech delay may have a significant impact on personal, social, academic and, later on, vocational life. Early identification and appropriate intervention may mitigate the emotional, social and cognitive deficits of this disability and may improve the outcome.

Normal Speech Development

To determine whether a child has speech delay, the physician must have a basic knowledge of speech milestones. Normal speech progresses through stages of cooing, babbling, echolalia, jargon, words and word combinations, and sentence formation. The normal pattern of speech development is shown in Table 1.³

Epidemiology

Exact figures that would document the prevalence of speech delay in children are difficult to obtain because of confused terminology, differences in diagnostic criteria, unreliability of unconfirmed parental observations, lack of reliable diagnostic procedures and methodologic problems in sampling and data retrieval. It can be said, however, that speech delay is a common childhood problem that affects 3 to 10 percent of children.^4–6 The disorder is three to four times more common in boys than in girls.^5,7

Etiology

Speech delay may be a manifestation of numerous disorders. Causes of the problem are listed in Table 2.

MENTAL RETARDATION

Mental retardation is the most common cause of speech delay, accounting for more than 50 percent of cases.⁸ A mentally retarded child demonstrates global language delay and also has delayed auditory comprehension and delayed use of gestures. In general, the more severe the mental retardation, the slower the acquisition of communicative speech. Speech development is relatively more delayed in mentally retarded children than are other fields of development.

In approximately 30 to 40 percent of children with mental retardation, the cause of the retardation cannot be determined, even after extensive investigation.⁹ Known causes of mental retardation include genetic defects, intrauterine infection, placental insufficiency, maternal medication, trauma to the central nervous system, hypoxia, kernicterus, hypothyroidism, poisoning, meningitis or encephalitis, and metabolic disorders.⁹

HEARING LOSS

Intact hearing in the first few years of life is vital to language and speech development. Hearing loss at an early stage of development may lead to profound speech delay.

Hearing loss may be conductive or sensorineural. Conductive loss is commonly caused by otitis media with effusion.¹⁰ Such hearing loss is intermittent and averages from 15 to 20 dB.¹¹ Some studies have shown that children with conductive hearing loss associated with middle ear fluid during the first few years of life are at risk for speech delay.^4,11 However, not all studies find this association.¹² Conductive hearing loss may also be caused by malformations of the middle ear structures and atresia of the external auditory canal.

Sensorineural hearing loss may result from intrauterine infection, kernicterus, ototoxic drugs, bacterial meningitis, hypoxia, intracranial hemorrhage, certain syndromes (e.g., Pendred syndrome, Waardenburg syndrome, Usher syndrome) and chromosomal abnormalities (e.g., trisomy syndromes). Sensorineural hearing loss is typically most severe in the higher frequencies.

MATURATION DELAY

Maturation delay (developmental language delay) accounts for a considerable percentage of late talkers. In this condition, a delay occurs in the maturation of the central neurologic process required to produce speech. The condition is more common in boys, and a family history of “late bloomers” is often present.¹³ The prognosis for these children is excellent, however; they usually have normal speech development by the age of school entry.¹⁴

EXPRESSIVE LANGUAGE DISORDER

Children with an expressive language disorder (developmental expressive aphasia) fail to develop the use of speech at the usual age. These children have normal intelligence, normal hearing, good emotional relationships and normal articulation skills. The primary deficit appears to be a brain dysfunction that results in an inability to translate ideas into speech. Comprehension of speech is appropriate to the age of the child. These children may use gestures to supplement their limited verbal expression. While a late bloomer will eventually develop normal speech, the child with an expressive language disorder will not do so without intervention.¹³ It is sometimes difficult, if not impossible, to distinguish at an early age a late bloomer from a child with an expressive language disorder. Maturation delay, however, is a much more common cause of speech delay than is expressive language disorder, which accounts for only a small percentage of cases. A child with expressive language disorder is at risk for language-based learning disabilities (dyslexia). Because this disorder is not self-correcting, active intervention is necessary.

BILINGUALISM

A bilingual home environment may cause a temporary delay in the onset of both languages. The bilingual child's comprehension of the two languages is normal for a child of the same age, however, and the child usually becomes proficient in both languages before the age of five years.

PSYCHOSOCIAL DEPRIVATION

Physical deprivation (e.g., poverty, poor housing, malnutrition) and social deprivation (e.g., inadequate linguistic stimulation, parental absenteeism, emotional stress, child neglect) have an adverse effect on speech development. Abused children who live with their families do not seem to have speech delay unless they are also subjected to neglect.¹⁵ Because abusive parents are more likely than other parents to ignore their children and less likely to use verbal means to communicate with them, abused children have an increased incidence of speech delay.¹⁶

AUTISM

Autism is a neurologically based developmental disorder; onset occurs before the child reaches the age of 36 months. Autism is characterized by delayed and deviant language development, failure to develop the ability to relate to others and ritualistic and compulsive behaviors, including stereotyped repetitive motor activity. A variety of speech abnormalities have been described, such as echolalia and pronoun reversal. The speech of some autistic children has an atonic, wooden or sing-song quality. Autistic children, in general, fail to make eye contact, smile socially, respond to being hugged or use gestures to communicate. Autism is three to four times more common in boys than in girls.

ELECTIVE MUTISM

Elective mutism is a condition in which children do not speak because they do not want to. Typically, children with elective mutism will speak when they are on their own, with their friends and sometimes with their parents, but they do not speak in school, in public situations or with strangers. The condition occurs somewhat more frequently in girls than in boys.¹⁷ A significant proportion of children with elective mutism also have articulatory or language deficits.

The basis of mutism is usually family psychopathology. Electively mute children usually manifest other symptoms of poor adjustment, such as poor peer relationships or overdependence on their parents. Generally, these children are negativistic, shy, timid and withdrawn. The disorder can persist for months or years.

RECEPTIVE APHASIA

A deficit in the comprehension of spoken language is the primary problem in receptive aphasia; production difficulties and speech delay stem from this disability. Children with receptive aphasia show normal responses to nonverbal auditory stimuli. Their parents often describe such children as “not listening” rather than “not hearing.” The speech of these children is not only delayed but also sparse, agrammatic and indistinct in articulation.¹⁸ Most children with receptive aphasia gradually acquire a language of their own, understood only by those who are familiar with them.

CEREBRAL PALSY

Delay in speech is common in children with cerebral palsy. Speech delay occurs most often in those with an athetoid type of cerebral palsy. The following factors, alone or in combination, may account for the speech delay: hearing loss, incoordination or spasticity of the muscles of the tongue, coexisting mental retardation or a defect in the cerebral cortex.

Clinical Evaluation

A history and physical examination are important in the evaluation of children with speech delay. The information obtained will help the physician select appropriate studies for further evaluation (Tables 3 and 4).

HISTORY

A thorough developmental history, with special attention to language milestones, is extremely important in making the diagnosis. The physician should be concerned if the child is not babbling by the age of 12 to 15 months, not comprehending simple commands by the age of 18 months, not talking by two years of age, not making sentences by three years of age, or is having difficulty telling a simple story by four to five years of age.^4,18 The physician should also be concerned if the child's speech is largely unintelligible after three years of age or if the child's speech is more than a year late in appearance in comparison with normal patterns of speech development. Generalized delay in all aspects of developmental milestones suggests mental retardation as the cause of a child's speech delay.

The medical history should include any maternal illnesses during the pregnancy, perinatal trauma, infections or asphyxia, gestational age at birth, birth weight, past health, use of ototoxic drugs, psychosocial history, language(s) spoken to the child, and family history of significant illness or speech delay.

PHYSICAL EXAMINATION AND SCREENING TESTS

A precise measurement of the child's height, weight and head circumference is necessary. A review of the appropriate parameter on the growth chart also can help in early identification of some types of speech delay. Any dysmorphic features or abnormal physical findings should be noted. A complete neurologic examination should be performed and should include vision and hearing evaluations.

The Early Language Milestone Scale (Figure 1) is a simple tool that can be used to assess language development in children who are younger than three years of age.¹⁹ The test focuses on expressive, receptive and visual language. It relies primarily on the parents' report, with occasional testing of the child. The test can be done in the physician's office and takes only a few minutes to administer.⁷ For children two and one-half to 18 years of age, the Peabody Picture Vocabulary Test–Revised²⁰ is a useful screening instrument for word comprehension. If the child is bilingual, it is important to compare the child's language performance with that of other bilingual children of similar cultural and linguistic backgrounds.

A comprehensive developmental assessment is essential, because a delay in speech development is the most common early manifestation of global intellectual impairment. The Denver Developmental Screening Test is the most popular test in clinical use for infants and young children.^9,21

Children whose results indicate an abnormal condition require more definitive testing with one of the standardized and validated tests of intelligence. The most widely used intelligence tests for assessing the intellectual and adaptive functioning of a child are the Stanford-Binet Intelligence Scale, the Bayley Scales of Infant Development, the Wechsler Intelligence Scale for Children–Revised (WISC–R), and the Wechsler Preschool and Primary Scale of Intelligence (WPPSI).

DIAGNOSTIC EVALUATION

All children with speech delay should be referred for audiometry, regardless of how well the child seems to hear in an office setting and regardless of whether other disabilities seem to account for the speech delay.⁸ Special earphones that shut out background noise may improve the study result. Tympanometry is a useful diagnostic tool. When coupled with results from pure-tone audiometry, measurement of eardrum compliance by means of a tympanometer helps to identify a potential conductive component (e.g., middle ear effusion) that might otherwise be missed. An auditory brain-stem response provides a definitive and quantitative physiologic means of ruling out peripheral hearing loss.²² It is especially useful in infants and uncooperative children.²² The auditory brain-stem response is not affected by sedation or general anesthesia.

Additional tests should be ordered only when they are indicated by the history or physical examination. A karyotype for chromosomal abnormalities and a DNA test should be considered in children who have the phenotypic appearance of fragile X syndrome. An electroencephalogram should be considered in children with seizures or with significant receptive language disabilities. The latter may occasionally be related to subclinical seizure activities in the temporal lobe.⁴

Management

The management of a child with speech delay should be individualized. The health care team might include the physician, a speech-language pathologist, an audiologist, a psychologist, an occupational therapist and a social worker. The physician should provide the team with information about the cause of the speech delay and be responsible for any medical treatment that is available to correct or minimize the handicap.

A speech-language pathologist plays an essential role in the formulation of treatment plans and target goals. The primary goal of language remediation is to teach the child strategies for comprehending spoken language and producing appropriate linguistic or communicative behavior. The speech-language pathologist can help parents learn ways of encouraging and enhancing the child's communicative skills.

In children with hearing loss, such measures as hearing aids, auditory training, lip-reading instruction and myringotomy may be indicated; occasionally, reconstruction of the external auditory canal, ossicular reconstruction and cochlear implantation may be necessary. The use of a high-risk registry as well as universal hearing screening may help to identify hearing loss at an early age.

Psychotherapy is indicated for the child with elective mutism. It is also recommended when the speech delay is accompanied by undue anxiety or depression. In autistic children, gains in speech acquisition have been reported with behavior therapy that includes operant conditioning.

Parents and caregivers who work with children with speech delay should be made aware of the need to adjust their speech to the level of the particular child. Teachers should consider the use of small group instruction for children with speech delay.²³