Autism spectrum disorder (ASD) is a biologically based neuro-developmental disorder clinically diagnosed through specialist ASD multidisciplinary (MDT) assessments based upon Diagnostic and Statistical Manual of Mental Disorders (DSM-V) Diagnostic Criteria.1,2
In order to meet the DSM-V Diagnostic Criteria for ASD a patient must demonstrate persistent deficiencies in both major domains: A) impairment in social communication and interaction B) restricted repetitive patterns of behaviour, interests, and activities.1
Identifying children at risk of ASD
As a developmental disorder, autism spectrum disorder (ASD) has a broad spectrum of presentations that varying throughout each individual’s life as well as between individuals. It is well documented that early identification of at risk individuals, with early diagnosis and intervention ultimately results in less challenging behaviours and improved outcomes for patients and their whānau.3
The expectation is by the age of two to three a child with moderate to severe ASD should be reliably diagnosed by an experienced clinician.4 Children on the less severe end of the spectrum may not may not present until they are exposed to the greater social demands of early childhood centres or primary school; although these children often have better language skills, they can still have significant needs.
Formal ASD population screening programmes are not recommended in New Zealand, but routine developmental surveillance is offered and widely available to all New Zealand’s children. This is provided through the Well Child/Tamariki Ora framework5 for under fives and beyond this through regular academic and behavioural reviews in school. Ensuring staff education, in addition to nurturing healthcare and childhood educational environments that are receptive to parental concerns remain critical in early identification of presenting signals.
Assessment
In New Zealand, inconsistent and inequitable access to assessment and diagnosis has lead to demand for an increase in structured pathways and validated diagnostic instruments to be utilised in conjunction with expert clinical judgment in the hope of providing consistency of the screening process and ultimate diagnosis.6,7
Following the suggested pathway (Figure 1) when concerns are raised the first step is referral to a community health or educational professional with experience in ASD who can elicit the concerns, the severity of the condition and collect additional information. If concerns are identified or unclear, this professional should refer to the local Developmental Services Coordinator who will collaborated information, ensure audiology screening is up to date and arrange the initial assessment with an appropriate agency.
The initial assessment is often undertaken by an individual practitioner then if they are concerned referral for further multidisciplinary assessment is appropriate. A Social Communication Questionnaire (SCQ) could be utilised by this broad range of professionals as a second-stage screening tool for ASD. Using a total score of 15 or higher to differentiate ASD from other diagnoses with a sensitivity of 85% and specificity of 75%.6
The specialist multidisciplinary team (MDT) assessment is designed to provide a robust assessment and diagnosis, therefore allowing for accurate planning of future services and supports. The specialist ASD MDT usually includes at least two or three members from the following professionals; paediatricians, child and adolescent psychiatrists, clinical or educational psychologists, speech-language therapists and occupational therapists.
The MDT assessment has two major objectives:
Providing a definitive diagnosis by excluding conditions that may produce symptoms suggestive of ASD
Guiding future management by screening for co-morbid conditions and building an individual strengths and challenges profile to tailor future intervention.8
History
This is usually obtained from the parents, but as the child gets older teachers and therapists can also provide useful observations.
A detailed developmental and behavioural history is particularly key in the diagnosis of ASD. This history should clearly elicit early language and social-emotional milestones, play skills, behaviour, and any regression. Exploring specific information centred around early communicative behaviours, such as use of eye contact, pointing and response to name. A history of ritualised, repetitive or stereotyped behaviours, such as hand flapping. Unusual visual behaviour, or preoccupation with parts of toys. Frequent tantrums and trouble tolerating change or transition.
In addition to a thorough past medical history, areas explored should include seizure activity, self-injury, significant disturbance in sleep or eating (including pica). Divergence suggestive of delayed development or of behavioural concerns . The record should include concerns that are voiced regarding hearing, vision, and speech/language. A social history is valuable in understanding the child’s home environment.
ASD has a strong genetic component and therefore warrants a thorough three-generation family history.9 This should specifically explore family history of ASD (including in previous terminology), seizures, genetic syndromes, language delay and learning, attentional, mood, tic and psychiatric disorders.
In some cases it may be useful to use a semi-structured interview such as the Autism Diagnostic Interview – Revised (ADI-R) This is a 2-3 hour semi-structured method exploring the history designed for experienced clinicians. It explores family background, developmental history, language, communication, social development, interests, and general behaviour. Then Grouping and scoring of answers under under four domains: reciprocal social interaction; communication; restricted, stereotypic behaviour; and age of presentation. For each domain, a range of sensitivity (86–100%) and specificity (75–96%) values are demonstrated. Importantly the ADI-R is useful for treatment and educational planning, regardless of the ultimate diagnosis.
Medical Examination
Communication deficits and behavioural symptoms recognised in ASD may limit cooperation with examination, it is therefore particularly important to allocate extra time to achieve a thorough examination. Direct observation of the child’s behaviour is often opportunistically monitored during the history taking. Observing patterns of play, responses to non-verbal communication and interaction with familiar and unfamiliar adults.
Dysmorphic features, growth parameter and ideally their trajectory should be a routine part of any paediatric examination. Height and weight measurements are necessary in children who are being evaluated for ASD, since dietary obsessions and compulsions can result in poor weight gain or obesity. Children with ASD have early acceleration of head growth, followed by stabilisation.10 Macrocephaly is recognised in an approximately 25 percent of children with isolated ASD. Microcephaly is present in only 15 percent of patients with ASD however this is usually associated with co-existing conditions.11
A full physical examination should be completed including a thorough neurological assessment. Children with ASD can have mild hypotonia4 but focal neurologic findings or asymmetry requiring further neurologic evaluation and likely neuro-imaging.
Clinical /Educational psychologist assessment
Focused observations should be taken across more than one setting as the familiarity of the setting (for example home, early childhood centre or school) often has significant impact on the skills and behaviours demonstrated by the child. Direct observations need to be systematic and examine communication, social and play skills.
Diagnostic Observation Schedule (ADOS) is semi-structured assessment with observational measures designed to assess reciprocal social interaction and communication, play, and use of imagination. It was originally developed to be used in conjunction with the Autism Diagnostic Interview (ADI). This combination of instruments in conjunction with a developmental history, corroborating information from other sources, and of course the use of clinical judgment has been deemed the Gold Standard’ for the assessment of ASD.4,6,8 It provides an overall score and scores for social interaction and communication. In a systematic review, the average sensitivity and specificity were 87 and 78 percent, respectively, for ASD.6
Cognitive development including patterns of skills as well as intellectual and adaptive functioning can be formally assessed. In ASD a comprehensive history and review of records is the most valuable tool for distinguishing ASD from other disorders. Global developmental delay or intellectual disability can be difficult to distinguish from ASD, particularly in young children. In young or non-verbal children cognitive deficits are challenging to assess and severe cognitive deficits may be associated with repetitive behaviours and mixed expressive/receptive language delay. In addition, a high percentage of individuals with ASD have cognitive deficits.
Further Therapist Assessments
There should be a low threshold for visual or mental health assessments. Occupational and physical therapist can be involved as required. Speech-language therapist assessment of speech and language.
Co-morbid Conditions
Once the diagnosis of ASD is confirmed, additional medical testing may be indicated. Additional evaluation may be necessary to identify co-morbid conditions that have important implications for treatment or genetic counselling and/or to definitively exclude some conditions in the differential diagnosis. A recognisable disorder is found in a minority of cases, usually in patients with co-morbid global developmental delay or intellectual disability. The most common of these disorders include tuberous sclerosis complex, fragile-X syndrome, and Angelman syndrome.
Evaluation for associated conditions should include genetic testing and may include metabolic testing, neuroimaging, and/or electroencephalography (EEG). These evaluations should be obtained as indicated based upon the history and clinical presentation as the yield of such testing in the absence of clinical indications is low.
Genetic Testing
Some sources suggest all children diagnosed with ASD receive chromosomal microarray and polymerase chain reaction for Fragile-X Syndrome. Karyotype is warranted if a balanced translocation is suspected.12 Additional genetic testing or geneticist involvement is indicated only for individuals with dysmorphic features, microcephaly, macrocephaly, cognitive impairment, suspicious medical or family history.
Metabolic Testing
Metabolic disease account for less than five percent of cases of ASD, testing is only indicated if there are symptoms or signs of a metabolic disorder.4
Electroencephalogram
Sleep-deprived EEG is indicated when there is a history of unusual spells or behaviours frankly suggestive of seizures and to exclude Landau-Kleffner syndrome (acquired epileptic aphasia) in patients with a significant regression in language skills.4
Summary
ASD is a developmental disorder that all health and education professional working with children should be educated to identify children at risk. The formal diagnosis requires a throughout specialist multidisciplinary assessment.