Autism



Developmental-Behavioral Pediatrics, 2008

Josh Mandelberg

Autism

• Definition – neurodevelopmental impairment of 1) reciprocal social interaction, 2) impaired communication (verbal & nonverbal) 3) deficits in play / imagination 4) repetitive/stereotyped behaviors

• See failure to develop joint attention (unable to share interests, pleasurable experiences or requests using gestures or verbal communication + eye contact with another person)

• Part of PDD (autism, Asperger’s, Rett’s, childhood disintigrative d/o, PDD-NOS), autistic spectrum d/o (ASD) used to denote less severe impairment

• Epi –

o 4-10 per 10K in 80’s now 67 per 10K in 2007 study

o recurrence rate in sibs is 2-8% (even without specific genetic Dx) = 50x rate of general population. If 2nd child has autism, recurrence risk is 25-35% Concordance 70% autism/90% ASD for monozygotic twins (vs 3% for dizygotic)

o males 3-4x more prevalent (no diff in race, ethnicity, SES)

o Co-morbidities –

▪ Mental retardation (50%),

▪ Seizure d/o (33% have 2+ unprovoked by adulthood, peak onset bimodal = early childhood & adolescent),

▪ Also hyperactivity or inattention, anxiety, obsessive-compulsive behavior, self-injurious behavior, pica, aggression.

▪ May have sleep d/o, GI or feeding d/o, allergies

o Increased prevalence causes: change in dx criteria/broader definition of ASD, incentive for services (diagnostic substitution), study sensitivity, increased public and professional awareness, availability of tx, possible true increase in prevalence

• Pathology

o Felt to be polygenetic d/o resulting from gene-environment interactions

o Historically thought from bad parenting (refrigerator mother). Neurologic basis more likely with prevalence of SZ, genetic links, pathological brain anomalies)

o Most cases idiopathic. Are cases with underlying metabolic, infectious or genetic d/o (untreated PKU, congenital CMV or rubella, tuberous sclerosis, fragile X, CHARGE synd, neurofibromatosis, Downs)

o Chromosomal hot spots identified include chromosome 6, 7, 13, 15, 16, 17 and 22. High rate of Fragile X syndrome (possibly up to 10%)

o Most non-regressive (subtle signs may not be identified at time – 1 year old birthday party video studies)

o Theory of mind – idea that kids with autism have difficult time understanding that other people have a different perspective

• Diagnosis

o Eval – screen with autism specific screening tools: CHAT (18m/o 14 ?’s, 98% specific, 38% sensitive because also + if mental retardation), Social Communication Questionaire (4y+), M-CHAT (24m/o, 23?, 87% specific, 99% sensitive, PPV ~5%) and M-CHAT Follow up Interview (PPV ~50%, see dbpeds) , STAT. Some have accelerated head growth 6m/o. ASD toolkit developed.

o Red flag milestones – no babble or point or use other gestures by 12m/o, no single words by 16m/o, no 2 word phrases by 24m/o, loss of language skills at any age

o Joint attention deficits see in: eye contact, respond to name, pointing, showing (triadic), can be spontaneous (8-10m follow mother’s gaze), responding (10-12m follow point and look back), initiating (request cookie – 12-14m, show parents object – 14-16m). Absence at 18-24m is red flag for autism (specific sign, global delay “show” when reach dev age 14-16m. Functional language within 1y of mastering joint attention)

o Social orienting (turn to name being called) – best early predictor 8-10m/o

o Pretend play – autism stay oral-motor, pretend play rare before 2y/o, prefer everyday objects to toys, play unusually with toys, prefer trial and error problems to observe and imitate

o Language – quiet, atypical vocalizations and speech (echolalic esp delayed and larger chunks, gestalt pseudophrases, popup words out of context), cry, fewer gestures

o Social development out of sync with motor + cognitive + adaptive development (physical handicap driven and compensate), autistic still seek comfort when hurt or anxious

o Features for early diagnosis (want 4/4 for provisional dx, emphasize social, DSM4 hard before 3rd B-day)

▪ Lack of spontaneous shared enjoyment (show, bring, point)

▪ Lack emotional/social reciprocity (drive to connect with others)

▪ Impaired nonverbal behaviors (eye contact, gestures, facial expression)

▪ Delayed language

o Communication Profile

▪ Rely on pre-symbolic communication (leading, pulling), lack of generalization, lack of gestures or odd gestures.

▪ Problem behaviors as attempt to communicate – screeching, hitting, fleeing.

▪ Literal interpretation of words as lack appreciation for non-verbal cues, difficulties with own non-verbal communication

▪ Early language have vocabulary limited to nouns and labels. Use chunk language and borrowed phrases (situation specific, blunt use of language). Expressive may appear better than receptive language

▪ Harder to acquire action words, modifiers and relationship words (i.e. prepositions) – probably because these are not static, require taking others’ perspective (theory of mind)

o Other features - Hard item and constant attachments, stereotypic behaviors (>2y/o, not specific for autism), repetitive behaviors, tantrum when try to stop. Sensory processing differences (sensitive to dripping water, oblivious to name calling, tactile defensiveness – sensory gating issue), Communication differences (most aberrant from peers at 4-5y/o, use of other’s body to communicate, inability to make small talk / reciprocal conversation, odd statements, pronoun reversal, idiosyncratic language, abnormal speech volume/intonation/rhythm/ rate)

o PDD – severe, pervasive impairment not meeting criteria for autism - examples:

▪ Abnormal social interactions – lack of joint attention, eye contact minimal or fleeting. Act withdrawn or unaware of others, or may be odd. May be affectionate and have normal attachment with caregivers. Lack ability to feel empathy. Difficulty with peer friendships – aloof or overly intrusive

▪ Atypical communication – regress in language skills, echolalia, scripted speech (from video or adult conversation), unusual prosody (monotone/singsong), pronoun reversal. Often lack 1 year old gestures (pointing, waving)

▪ Restricted activities – little imaginative play, prefer repetitive games or routines with toys (line up, smelling), focus on sensory aspects of objects (spinning, flashing lights), fascination with unusual objects. Demand sameness in routines, placement of objects, rituals and get agitated with change. Repetitive movements

▪ Nonverbal skills – advanced skills (word decoding, aka hyperlexia, but often lack commensurate reading comprehension)

▪ Sensory sensitivities – can be hyper or hypo sensitive (noise, texture, pain)

• DDx –

o Global developmental delay / mental retardation

o Developmental Language d/o – normal social interaction and play (can be confusing if anxiety or significantly inhibited temperament)

o Hearing Impairment – must rule out

o Landau-Kleffner syndrome (acquired epileptic aphasia), see regression of language, dx by sleep-deprived EEG

o Rett’s syndrome – sporatic X-linked d/o of girls. Decelerated head growth, stereotypic hand movements, dementia (MECP2 gene)

o Childhood disintegrative d/o – rarer than autism, normal development followed by regression in 2+ areas: language, social skill, adaptive behavior, bowel/bladder control, play/motor skills

o Reactive attachment d/o (severe early deprivation) – abuse, neglect, orphanage

o Anxiety d/o / OCD – may have overlap but should have good joint attention and reciprocal social relations

• Medical Evaluation (90% idiopathic, specific unifactorial diagnosis in 6-15%) –

o H+P (most idiopathic with unremarkable exam, normal neuro exam and no motor abnormalities. May have isolated macrocephally)

o Formal audiology eval (significant hearing loss can affect socialization as well as language), vision testing on all children

o Lead level (esp if pica, persistent mouthing or social risk)

o Wood’s lamp eval (3-4% of autism is Tuberous Sclerosis) esp if seizures

o fragile X (7-8% of autism is Frag X),

o high res chromosome analysis (5% yield), subtelomeric FISH (esp if MR, dysmorphic, congenital anomalies, FHx of MR or autism),

o Genetics tests (2nd tier tests)

▪ CGH – yield not yet determined (may identify 10% more than chromosomes alone)

▪ MECP2 gene in females (5% yield)

▪ PTEN gene in large head circumference (3% if head circumference >2.5SD)

o Repeat newborn screen if not available or performed

o EEG (Landau-Kleffner, not routinely indicated in autism eval but consider if concern for SZ or significant later regression)

o MRI not indicated but consider if SZ or focal neuro exam

o Genetics consult can consider in any child

o Metabolic studies if suggestive

▪ screening tool if negative recheck 1mo

o Comprehensive eval

▪ Thorough Hx (3 generation pedigree)

▪ Detailed PEx (focus neuro, dysmorphic)

▪ Developmental eval

▪ Standardized ASD tool (ADOS - observed, ADI - interview)

▪ Assessment of family’s strength and needs

▪ Search for etiology based on 1-5

Autism Interventions

• Goal to minimize core features and deficits, maximize quality of life, alleviate family distress – facilitate learning, promote socialization, reduce maladaptive behaviors, educating and supporting families. Better outcomes suggest with earliest intervention

• Indiv with disabilities act mandates educational services for autism – 2001 National Research Council recommend 25h/w instruction, 12mo/yr, teacher:student ratio ................
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