What Is a Developmental Disability?

Approximately 17% of Americans younger than 18 years have been diagnosed with a developmental disability. The 2000 reauthorization of the Developmental Disabilities Act defines developmental disability as a “severe, chronic disability in an individual five years of age or older that is attributable to a mental or physical impairment or a combination of mental and physical impairments.” The developmental disability must manifest before 22 years of age, continue indefinitely, and result in substantial functional limitation in multiple areas of life. Children with developmental disabilities often have complex health care needs and may receive care from multiple subspecialists. Such patients are also identified as having special health care needs, which is discussed in Chapter 16.

What Developmental Disabilities Am I Likely to See?

A review of every developmental disability is beyond the scope of this chapter. The focus is on autistic disorder, cerebral palsy, and Down syndrome because they are common and because management principles may be applied to other developmental diagnoses. Diagnosis and management of common associated health issues will be reviewed. Where appropriate, information about incidence and genetic factors will be provided. Finally, you will be referred to text and electronic resources for more developmental disability-related information.

Who Is at Risk for Developmental Disability?

Developmental disabilities occur in every race and socioeconomic group. As outlined in Chapter 27, genetic, prenatal, and perinatal factors contribute to the genesis of certain developmental disorders. Children with these predisposing factors may be at higher risk of disability. Many affected children, however, have unremarkable family, prenatal and birth histories.

What Is Autism?

Autism, or autistic disorder (AD), was first described by Leo Kanner in 1943. Decades ago, the medical community believed that AD was caused by cold and rejecting mothers. Most investigators today agree on a neurobiologic cause, although a specific lesion has not been identified. AD is one of five autism spectrum disorders that are classified under the category of pervasive developmental disorders (PDDs) in the Diagnostic and Statistical Manual (DSM-IV). The diagnosis of AD requires symptoms in three areas:

What Are the Other Autistic Spectrum Disorders?

The other autistic spectrum disorders have various combinations of the AD clinical features. Children with Asperger’s disorder have problems with social interaction, pragmatic language, and restricted interests but show normal cognitive abilities and language development. Rett syndrome is an X-linked condition affecting girls that typically has onset before age 4 years. Patients with Rett syndrome have deceleration of head growth plus loss of social skills, expressive language, and both gross motor and purposeful hand skills. Childhood disintegrative disorder is diagnosed in children who demonstrated normal development for at least 2 years then began to regress in more than one developmental area. Pervasive developmental disorder not otherwise specified (PDD-NOS) describes children who display some autistic symptoms but do not meet the criteria for the other four spectrum disorders.

How Common Is Autistic Disorder?

Autistic spectrum disorder develops in 60 out of 10,000 children. Boys have more than three times higher risk than girls. Autism in girls, however, is much more likely to be accompanied by significant mental retardation. AD coexists with some degree of mental retardation in 70% of cases. Often, AD can be correlated with a specific genetic, metabolic, or structural cause of mental retardation, including fragile X syndrome, tuberous sclerosis, Angelman syndrome, Down syndrome, phenylketonuria, neurofibromatosis, Rett syndrome, or congenital brain malformation.

What Causes Autism?

There is no unifying hypothesis about the etiology of autism. Neuroanatomic, neurochemical, neuroelectrical, and genetic factors have all been implicated. Various brain anomalies are commonly seen on imaging studies, and seizure disorders occur in 11% to 42% of individuals with AD. Neurochemical studies suggest abnormal neurotransmitter activity in some autistic individuals, although the significance of this finding is not clear. The evidence for a genetic basis is striking: AD has a 60% concordance in monozygotic twins. Siblings of autistic individuals have up to 25 to 50 times higher risk of AD than the general population. First-degree relatives of individuals with AD have higher than average rates of personality traits such as anxiety, rigidity, and social awkwardness, a group of traits known as the broader autism phenotype (BAP). BAP implies that the spectrum of autistic traits may be much wider than originally thought. A single gene has not been identified, but studies to date point to three locations: the long arm of chromosome 7 (7q), a region on the long arm of chromosome 15, and a region on chromosome 13.

What History Is Needed to Diagnose Autism?

Family members or teachers are very likely to express concern about a child’s language, social development, or behavior. Your task is to obtain a detailed history with particular attention to communication, social skills, and behaviors. Table 58-1 shows a general list of associated signs and symptoms. Screening tools such as the Checklist for Autism in Toddlers (CHAT) help focus your questions during primary care visits. The five key items from the CHAT can be found in Table 58-2. Children who fail all these items have a high risk of developing autism.

Table 58-1 Impairments Common to Autistic Syndromes

Table 58-2 5 Key Items in the CHAT (Failure of All 5 Means High Risk for Autism)

How Should I Assess Communication?

You must assess for speech and language delay because most children with AD acquire these skills much more slowly than motor skills. Ask family members if the child communicates with words and sentences, by pointing, use of hand signs, or jargoning. If the child speaks, inquire about vocabulary size and complexity of utterances. Next, ask about unusual features of speech. Does the child often echo what he or she hears? Immediate echolalia occurs when a child promptly repeats the final fragments of sentences or songs; delayed echolalia occurs when the child repeats past information out of context. A child with AD/PDD commonly demonstrates delayed echolalia by habitually reciting portions of movies or television programs. In addition, a child may also misuse pronouns, speak in a pedantic tone of voice, or fail to respond to his or her own name. Hearing loss, language disorders, and some learning disabilities can mimic AD/PDD symptoms. Evaluation by an interdisciplinary team should include audiometry, psychometric testing, and speech and language assessment, in addition to cognitive testing and a medical evaluation.

How Does a Child with Autistic Disorder Interact with Others?

Social skills are delayed relative to developmental age in AD/PDD. Examples of social deficits include poor eye contact, incongruent facial expressions, inappropriate volume or rate of speech, and resistance to being touched. A good screening question is “Does your child point out things for you to look at?” A normally developing young child usually draws the attention of a parent or other adult to an object of interest by pointing, reciprocal eye contact, verbalizations, and body language. These joint attention behaviors demonstrate the child’s growing awareness that others may share their experiences. Young children with AD/PDD perform far fewer joint attention behaviors than do typical children. They are occasionally described by parents as less interested in cuddling than their siblings, although this may vary markedly. Ask if the child seeks comfort from parents when hurt, and if he initiates hugs and kisses.

What Are Restricted Activities?

A child may “ignore” surroundings and people, yet show unusual interest in a single object such as a ceiling fan or running water. Pretend play is reduced in children with AD/PDD, so it is appropriate to inquire about favorite toys and activities, and about the nature of play. If the child likes to play with toy cars, does he set up races and crashes, make appropriate noises, and put toy figures inside the cars? Or does he play with them by lining them up or banging them together? Ask about play that is imitative of adult activity such as cooking on a toy stove or pretending to drive a toy vehicle. Also inquire if the child has a transitional object, such as a teddy bear. A child with AD/PDD tends not to have such objects or may choose an unusual item, such as a wooden spoon.

What Repetitive Activities Characterize Autistic Disorder?

Repetitive activities in AD/PDD may take many forms, including hand flapping, finger posturing, rocking, and spinning. Children may play for hours looping a particular piece of string or pouring water from one cup into another. The propensity for repetition may be demonstrated by a rigid insistence on routine, with severe behavioral outbursts greeting even a minor alteration in routine.

What Developmental Findings Suggest Autism?

It is especially important to consider the child’s overall developmental status before concluding that a particular symptom is indicative of AD/PDD. For example, a 5-year-old boy with known mental retardation may have a developmental age of 18 months. He may prefer to play alongside, but not with, other children, may flap his hands when excited, and speak only in 2-word phrases. His behaviors are consistent with his delayed development and do not by themselves support a diagnosis of AD/PDD.

What Should I Look for on Physical Examination?

The examination is an opportunity to observe the child’s interactions with family members and with you. Note how the child responds to his or her name and to instructions. You should look carefully for dysmorphic features, including microcephaly and neurocutaneous disorders.

What Workup Is Indicated for Autistic Disorder/Pervasive Developmental Disorder?

The diagnosis is based entirely on clinical findings and the DSM-IV criteria. Laboratory tests are indicated mainly to evaluate clinical suspicions of an associated acquired or congenital disorder. Consider blood lead level if the lead screening history is positive. Molecular genetic studies are needed if findings suggest fragile X syndrome. MECP2 mutation study is appropriate in a girl with slow head growth and suspected Rett syndrome. Electroencephalogram (EEG) may be indicated if the history suggests seizure activity. Head imaging may be helpful for a child with cranial abnormalities or suspicion of neurocutaneous disease. A child with dysmorphic features or findings suggestive of neurocutaneous disorder may benefit from referral to a medical geneticist for further evaluation.

How Is Autism Treated?

At this writing, autism and its spectrum disorders cannot be cured. Most treatment plans emphasize intensive academic and behavioral intervention beginning as soon as possible after the diagnosis is made. Classroom environments must be highly structured, heavily reliant on visual aids, and provide frequent positive reinforcement to the child. Behavioral techniques are used to teach social skills and activities of daily living. Parents need to be trained in these techniques to teach their children at home.

Are Medications Ever Useful?

Psychotropic medications may provide isolated benefits to some children with severe behavioral challenges. Atypical antipsychotic agents, including risperidone and quetiapine, have been shown to reduce aggressive behaviors in autistic children and are generally well tolerated. Selective serotonin reuptake inhibitors may alleviate the rigidity and perseveration of some autistic symptoms. Drug therapy is not indicated for or useful in treatment of social or language deficits associated with AD/PDD.

Do “Alternative” Treatments Help?

Although it is critical that you listen to parental concerns and beliefs, you also must provide appropriate, reliable, valid information to counter the misinformation that abounds in popular media and on the Internet. Elimination diets, vitamin and herb supplements, heavy metal chelation, and avoidance of immunizations all are examples of practices favored by many parents of children with AD/PDD. None of these measures has been demonstrated to be safe or effective and none can be recommended. Immunizations have no identified relationship to any of the autistic spectrum disorders, and referral to reliable Web sites such as those of the Centers for Disease Control and Prevention and the American Academy of Pediatrics may be helpful to families. Avoidance of immunizations puts a child at risk for preventable infections.

What Is Cerebral Palsy?

Cerebral palsy describes a group of static, nonprogressive disorders of the developing brain. Although it may manifest in many different ways, cerebral palsy is consistently characterized by abnormalities in muscle tone and posture and by some degree of permanent motor impairment.

The incidence of cerebral palsy is between 2 and 3 per 1000 births, a figure that has not changed for the past two decades.

How Is Cerebral Palsy Classified?

Individual cases are classified by subtype and by distribution of neurologic impairment. Approximately 80% of patients have one of the three subtypes of cerebral palsy; the remaining 20% demonstrate either a mix of subtypes or muscle rigidity throughout range of motion.

What Are the Subtypes of Cerebral Palsy?

Which Regions of the Body Are Affected?

Cerebral palsy of the spastic subtype is further classified by the distribution of neurologic impairment. Diplegia refers to impairment of trunk and extremities, with the lower extremities usually most severely affected. Hemiplegia describes impairment of function of only one side of the body. Quadriplegia affects all extremities, plus truncal, head, and neck musculature. Paraplegia, involvement of the lower extremities alone, is rare, as are monoplegia and triplegia.

What Causes Cerebral Palsy?

Any agent that damages the immature brain is capable of causing cerebral palsy. A list of potential etiologic factors is provided in Table 58-3. Note that causative factors in preterm and term infants differ somewhat. Also bear in mind that many children with cerebral palsy may not have histories indicative of any of these etiologies. Maternal infection, neonatal infection, and coagulopathy have emerged as important etiologic agents in the past decade, while birth asphyxia is now thought to account for a minority of cases. Extreme prematurity and multiple gestations are also increasingly significant etiologic factors.

Table 58-3 Factors Associated With Development of Cerebral Palsy