Child with possible autism spectrum disorder
The purpose of assessment in ASD (autism spectrum disorder) is to make a diagnosis where applicable and guide interventions and treatment based on a profile of strengths, impairments, skills and needs of the child and family. This includes identification of co-morbidities and associated developmental problems which can have significant impact on a child with ASD and their family. Diagnosis may be difficult due to communication impairment and possible associated cognitive problems, making it hard to determine whether the features are the result of ASD, due to comorbid conditions, environmental factors, or a combination of all three. For UK practitioners, the NICE guideline on assessment and diagnosis of ASD recommends that children and young people with suspected ASD have access to a local multidisciplinary autism team who can provide advice and expertise in assessing and formulating both the individuals’ and their family’s profile.
The diagnosis of ASD is based on developmental history and direct observation looking for behavioural features. Information about symptoms and signs and direct observations should be gathered from different settings, including home, education and other settings including social care services (if applicable), noting the duration, severity and impact. The features should be pervasive, but may appear different across the various settings.
Interpretation should take into account the child’s overall development, medical history and presence of risk factors. Absence of certain symptoms and signs does not exclude an ASD diagnosis e.g. poor eye contact, social smiling. Likewise presence of symptoms and signs consistent with ASD may be accounted for by other factors. It is important to note that a lack of concern from the parents about early development does not imply a
normal developmental history.
Standardized instruments can be used to provide a structure for assessment and are reviewed in NICE guidelines. Assessments should be undertaken by professionals with definite clinical competencies in ASD assessment, diagnosis and intervention planning. Standardised instruments are not essential for every assessment, but may enhance or facilitate diagnosis in that they can bring a broader understanding to the strengths and difficulties experienced by the patient and family. They should not be used in isolation and are less reliable in the younger age group (less than 2 years.) The differential diagnosis for ASD is listed in below, and should help guide further assessment.
Differential diagnosis of autism spectrum disorder Differential diagnoses may also be coexisting conditions
– Global developmental delay
– Intellectual disability
– Hearing problems
– Visual impairment
– Specific language disorders
– Social communication disorder
– Selective mutism
– Obsessive compulsive disorder
– Reactive attachment disorder/Maltreatment
– Lack of opportunity for interaction
– Rett syndrome (if features of regression)
– Epileptic encephalopathy
When to refer for specialist review
Key features indicating that further evaluation is essential are absence of babble, gesture or pointing by 12 months, no single words by 18 months, no two-word spontaneous phrase (nonechoed) by 24 months and any loss of language or social skills at any age. Developmental concerns raised in a preschool child will tend to generate initial referral through child health e.g. presentation with developmental delay or speech and language difficulties. The entry point is more diverse in school-age children as they can present with a broader range of symptoms.
General physical examination should be performed as part of the assessment and include a full neurological examination, looking for dysmorphisms, neurocutaneous stigmata and include Woods light (ultraviolet light) examination. Signs of injury, self-harm and possible maltreatment should be recognized. Observation of behaviour in different settings, e.g. home and school/nursery/play group, will allow assessment of the child in environments with varied social structures and give an impression of how the child interacts with peers and adults and how they adapt to predictable and less predictable routines. An autism-specific observational assessment such as the Autism Diagnostic Observational Schedule (ADOS) can provide useful information about social communication, repetitive behaviours and play skills during a set of standardised social situations with a professional trained to administer the tasks.
Where a possible hearing or visual impairment is suspected then it is helpful to rule out these problems first. Subsequent investigations should aim to exclude or identify medical conditions associated with ASD, but should only be performed where there are clinical indications and/or specific management, treatment or genetic implications. Investigative yield for biomedical testing is quoted as between 8% and 37% depending on the population studied. Array comparative genomic hybridisation (Microarray
CGH) has largely replaced karyotyping and can identify rare ‘causal’ copy number variants associated with ASD. Clinical practice varies as to which children should receive a microarray. Some target those where there is a higher yield of positive results i.e. lower IQ and dysmorphisms and some services are offering testing to all. Ultimately investigations should be guided by clinical presentation and family history and may include genetic testing for Fragile X or Rett’s syndrome.
Given the relatively low yield and potential for false-positive investigation, neuroimaging and EEGs should only be performed if there is a clinical indication. Similarly, evaluation of the gastrointestinal tract should be guided by clinical presentation and follow standard evaluation as for any child.