ASD is a neurodevelopmental disorder often identified at an early age and is characterised by functional impairment in social communication and restricted interests and repetitive behaviours. The term ASD, as defined in DSM-5, covers all the diagnostic terms that are previously used including Asperger syndrome, autistic disorder, pervasive developmental disorder-not otherwise specified (PDD-NOS).
ASD affects 1 in 88 children in the United States, with 1 in 56 boys affected. It is associated with intellectual disability in 55%, with other mental health disorders including ADHD, anxiety and conduct disorder in 70% and epilepsy in 30%. Common and rare genetic variants as well as environmental factors likely contribute to ASD risk. Through integrated analysis of de novo copy number variants, Indels and single nucleotide variants, currently 71 genetic risk loci have been associated with ASD. Genes that regulate chromatin, transcription and synapse formation have been implicated in the pathogenesis of ASD. This complex genetic picture with wide variety of clinical presentations suggests that many different subtypes of ASD may be identified in the future.
Although “no two kids with autism are the same”, they all share some common features including abnormal sensory processing that can predispose them to sensory overload in an average hospital setting. Sensory sensitivities may affect 42-80% of individuals with ASD. They may over or under-react to it. These include auditory, visual, gustatory and tactile input.
Management is divided into pharmacological and non-pharmacological interventions. Pharmacological interventions includes atypical antipsychotics that are aimed at controlling challenging behaviours and aggression, antidepressants (SSRIs and SNRIs) to improve repetitive behaviours as well as anxiety/depression, alpha-2 agonists to improve irritability and sensory sensitivities as well as sleep disorders and stimulants to treat hyperactivity, impulsivity and inattention. Anticonvulsants are used to control co-morbid seizure disorders.
The non-pharmacological interventions include a diverse group of approaches such as applied behavioural analysis, use of social stories and visual strategies to facilitate understanding. In addition, Complementary and Alternative therapies (CAM) are used widely. By the time the child receives the formal diagnosis of ASD, nearly a third already have tried it. The National Institute for Health and Care Excellence guidelines recommend not to use secretin, chelation, or hyperbaric oxygen therapy to manage ASD in any context because there is no evidence it is effective and because there is potential harm associated with their use. It is important to inquire about the use of CAM.
While there may be unique anaesthetic concerns for each child with ASD, common anaesthetic issues are a combination of significant anxiety, lack of understanding of the surroundings, sensory hypersensitivities and sensory overload in a busy, noisy hospital, communication difficulties and change of routine that in combination can lead to behavioural challenges at induction and in the recovery room as well as the wards.
Traditionally, restraint and intramuscular ketamine has been used. Later, the use of oral ketamine or the combination of ketamine and midazolam have been reported. Also, case reports of the use of alpha-2 agonists have been emerging with 93% successfully completing EEG in Mehta study after oral clonidine, 98.7% success with MRI or EEG in Lubisch study after mostly intravenous dexmedetomidine and 84% adequate sedation for intravenous cannula placement or induction in Zub study after oral dexmedetomidine. In another retrospective study by Ray et al. oral dexmedetomidine was used for sedation during EEG in 18 patients. More recently a more systematic approach has been used. It involves preparation of hospital, staff and the child as well as the use of premedication if necessary.
Early identification and planning in advance and a quiet room for admission and recovery have been described. More attention to preparation of children at home with social stories and the use of premedication and personal computer/ games for distraction at induction are necessary and effective. Parents are the experts in their children and their views should be valued. Many children with ASD can be very cooperative as long as they are prepared and understand what is expected of them.
Staff education and awareness of alternative communication methods, use of simple language with pictures, avoidance of triggers to challenging behaviour and ways to deal with aggressive behaviour are also important.
Intramuscular ketamine and significant restraint should be used rarely and only in extreme circumstances.