History
When eliciting history from the parents, reviewing pregnancy, peripartum, and infancy behaviors can yield clues to the genetic etiology of pervasive developmental disorder (PDD/ASD) behaviors or inform the decision whether to perform brain imaging. Many parents of children later diagnosed with autism can recall that, as an infant, their child had poor eye contact and was unlike older siblings in interpersonal interactions. Studies using the 1-year birthday party as a developmental milestone show that these children lack interest in the party, do not engage with adults, and/or show inappropriate interest in the gifts or activities.
A significant history of neglect or failure to thrive requires consideration of reactive attachment disorder, which is an important differential diagnosis of ASD. If the child has a clinically significant history of physical or emotional deprivation, a diagnosis of ASD should be deferred until the child has had an opportunity to recover in an enriched environment.
A common misconception is that children with a ASD do not show attachment to parent figures. In fact, many children with ASD have an emotional attachment to parental figures, but the attachment may manifest mostly as separation anxiety or as a seeking of comfort in odd ways. Children whose first language is not English may pose additional challenges in differentiating ASD from selective mutism and language disorders.
A thorough medical review is important, because none of the ASDs have a medical cure. Treatable conditions may cause symptoms of ASD, or they may worsen behaviors associated with these disorders.
Any history of deficiencies in the following areas is an indication for an evaluation for PDD:
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Language development
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Social interaction
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Sensory integration
Language development
Delay suggests autism or PDD not otherwise specified.
Regression is consistent with Rett disorder or childhood disintegrative disorder but may also be an important subtype of autistic disorder. [31]
Normal language development is a diagnostic feature of Asperger disorder. Problems with the pragmatics of language become more apparent with age.
Poor social interaction
Features include the following:
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Social isolation
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Poor eye contact
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Attachment to unusual objects
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Overdeveloped, circumscribed interests in odd or specific topics
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Inability to engage in imaginative play
Sensory integration difficulties
Features include the following:
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Oral aversion to certain textures or colors
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Olfactory aversion
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Tactile aversion to certain fabrics (eg, tags on clothing, position of socks)
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Auditory aversion to loud noises or types of music
Stereotyped behaviors/Restrictive Interests
Stereotyped behaviors are also an indication for an evaluation for ASD. Such behaviors include hand flapping and self-injurious behavior (eg, head banging). Children with stereotyped behavior may have difficulty making a transition between activities. In older children or adults, narrow interests which cause conflict in social interactions also warrant evaluation for ASD. High functioning individuals may present as experts in obscure topics.
Screening in the pediatric visit
The social communication questionnaire (SCQ) is a short parent report of current and past behavior. It has been validated to be consistent with the Autism Diagnostic Observation Schedule (ADOS) and has excellent sensitivity and specificity for ASDs. [32] The form is filled out by parents of children who are aged 4 years or older and have a mental age of 2 years. It is short enough to be completed in the waiting room.
The Developmental and Behavioral Pediatrics subgroup of the American Academy of Pediatrics recommends using the Modified Checklist for Autism in Toddlers (M-CHAT) form [5] to screen for symptoms in children aged 16-30 months. The checklist has been translated into Chinese [33] and many other languages, with differing degrees of validation in progress.
Physical Examination
Physical examination findings in children with pervasive developmental disorder (PDD/ASD) are usually normal, but the evaluation should be thorough in order to identify genetic or metabolic disorders.
The most important exception is Rett disorder; almost all patients who present with this disorder have the characteristic findings of hand-wringing, hyperventilation, or both. Unlike children with autism, who tend to have larger head circumference (>90%), children with Rett disorder have smaller head circumference (< 10%). Children with fragile X syndrome have a larger head circumference, while children with both fragile X syndrome and autistic disorder have even larger mean head circumference as a group. [8]
Children with ASD often have constipation, diarrhea, or reflux that they may lack the verbal ability to report. Untreated conditions present as disruptive behavior. A physical examination may be the only method to identify these issues. Food allergies may be the etiology of these gastrointestinal issues. Physical findings of eczema, wheezing, and poor weight gain should heighten the suspicion for food allergies. [34]
Complications
Early identification and treatment leads to better prognosis and outcomes. As discussed earlier, in the United States, age of identification varies from state to state. Resources for treatment are also geographically dependent. Non-verbal children have difficulty reporting symptoms and signs of acute illness and should warrant a careful physical exam for changes in behavior.
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Young child with fragile X syndrome who does not have obvious dysmorphic features. Courtesy of Randi J Hagerman, MD, FAAP.
