Autistic Spectrum Disorders The 5 Minute Pediatric Consult


	Autistic Spectrum Disorders

Patricia T. Molloy

Database
Differential Diagnosis
Data Gathering
Physical Examination
Laboratory Aids
Therapy
Follow-Up
Common Questions and Answers
Bibliography

DATABASE

DEFINITION

Autism is a chronic, nonprogressive developmental disability with a classic triad of impairment in social interaction, communication, and behavior. DSM-IV categorizes autistic disorder under the more general rubric of pervasive developmental disorders, which have in common impairments in social and communicative interaction with restricted interests or repetitive behavior. IQ ranges from retarded to above average. Most, but not all, children with autism have some degree of mental retardation and may develop epilepsy.

EPIDEMIOLOGY

The estimated prevalence of autism ranges from 4 to 5 cases per 10,000 to 15 cases per 10,000.

ETIOLOGY

No single underlying cause for autism has been identified. Disorders found to be either in association with or causative for autism include:

Prenatal: toxemia, rubella, cytomegalovirus, toxoplasmosis
Perinatal: anoxia, trauma, hyperbilirubinemia
Chromosomal: fragile X syndrome, trisomy 21, XYY syndrome, tuberous sclerosis
Metabolic: phenylketonuria, hyperthyroidism, lead ingestion, histidinemia, lipidosis
Congenital: microcephaly, hydrocephalus, Dandy-Walker syndrome
Acquired: infantile spasms, meningitis, encephalitis

Of the hereditary diseases associated with autism, fragile X is the most commonly reported. The frequency of fragile X syndrome among autistic males is 7.7% and among autistic females is estimated at 12.3%.

CLINICAL PRESENTING SIGNS AND SYMPTOMS

Speech and language delay
Limited eye contact
Severe sleep problems
Feeding difficulties
Signs of deafness
Temper tantrums
Stereotypies (i.e., rocking, hand flapping)
Fascination with parts of toys (i.e., rotating wheels)
Attachment to unusual objects
Hyperactivity or hypoactivity
Distress with changes in routine
Little pretend or imitative play

DIFFERENTIAL DIAGNOSIS

Major differential diagnoses of autistic behaviors include:

Mental retardation
Rett syndrome occurs only in females initially. Normal development followed by deceleration in head growth (“progressive microcephaly”), marked regression in development. Autistic features may develop with loss of purposeful hand movements, followed by repetitive hand-wringing or other repetitive behavior.
Evidence of schizophrenia (hallucinations, delusions) excludes autism. Mental retardation is characterized by IQ,70 with delayed early milestones and delayed adaptive skills, with communication and social skills that are appropriate for mental age. Schizophrenia is characterized by periods of remission, without mental retardation; development may be normal.
Diagnosis of attention-deficit hyperactivity disorder (ADHD) and autism are mutually exclusive diagnoses according to DSM-IV, though autistic syndromes may encompass symptoms of ADHD.

DATA GATHERING

HISTORY

A complete prenatal, neonatal, and childhood history helps to detect risk factors.

Failure to thrive due to peculiar eating habits may be noted.
Diagnosis is frequently based on a history of impaired verbal/nonverbal communication, social isolation, poor eye contact, stereotyped behavior, resistance to change, and tactile defensiveness.
A history of incoordination, paroxysmal disturbance suggesting epilepsy (staring spells, convulsions), and fragmented sleep are frequently present.

PHYSICAL EXAMINATION

Secondary growth disturbance (due to reflux, aversive feeding behavior) should be sought in growth curves.
Evidence of self-injurious behavior (excoriations, bruising, hair loss)
Physical findings may suggest alternate (metabolic) disorders or the underlying basis of autism:
- Long, thin face and prominent ears are characteristic of fragile X, and macroorchidism may not be present until after puberty.
- Pigmented lesions may suggest neurocutaneous syndromes, especially hypopigmented macules or fibromas indicating tuberous sclerosis.
- Microcephaly suggests TORCH infection (toxoplasmosis, rubella, cytomegalovirus, herpes infection), Angelman syndrome, or Rett syndrome.
- Macrocephaly suggests neurocutaneous disorder, storage disease, or hydrocephalus, or it may have no clear underlying cause.
- Neurologic examination: Spasticity, visual loss, or ataxia suggests leukodystrophy. Neurologic examination is necessary for assessment of stereotypic behavior, involuntary movements, abnormalities in motor coordination, and mirror or other overflow movements.
- Ophthalmologic and audiologic evaluations are necessary to rule out visual and hearing deficits.

LABORATORY AIDS

Neurodiagnostic tests may not be useful unless specific neurologic disorders are suspected. While some studies suggest minor structural abnormalities of the brain in autism (e.g., small cerebellum, open operculum), such findings are of limited diagnostic or practical value.

TESTS

EEG
- Significance: 20% to 40% of autistic patients develop seizures.
Chromosomes/fragile X
- Significance: appropriate for all autistic patients; helpful for genetic counseling
Inborn error screen
- Significance: to detect PKU, other amino acid disorders.
Head MRI/CT
- Significance: focal neurologic deficit to evaluate structural CNS abnormalities of cortex, cerebellum, brainstem, microcephaly/macrocephaly
TORCH (toxoplasmosis, rubella, cytomegalovirus, herpesvirus) titers
- Significance: microcephaly
Complete blood count
- Significance: growth delay, hyperactivity, pica
Blood lead level
- Significance: lead intoxication
Thyroid function tests
- Significance: for hypothyroidism
Audiogram/BAER
- Significance: speech and language delay, signs of hearing loss

THERAPY

MEDICAL MANAGEMENT

Though pharmacological therapy is frequently unsuccessful, target symptoms for a trial of medical therapy include:

Self-injurious behavior: fenfluramine, naltrexone
Sleep disturbances: benzodiazepines, melatonin
Seizures: barbiturates (may worsen hyperactivity), carbamazepine, phenytoin, valproate, others
Motor hyperactivity: clonidine, tricyclic antidepressants, methylphenidate (may worsen symptoms)
Violent rages: lithium, tricyclic antidepressants, L-dopa. Autistic children generally get worse on stimulants, with increased stereo-typies and worsening behavior. Neuroleptics (dopamine blockers) such as haloperidol and fluphenazine and resperidone decrease behavioral symptoms and can increase learning; morbidity includes movement disorders (tardive dyskinesias), risk of neuroleptic malignant syndrome. Clonidine is often the mainstay of treatment.

EDUCATIONAL/PSYCHOSOCIAL/MEDICAL MANAGEMENT

A complete psychoeducational assessment and treatment plan for intellectual, developmental, adaptive, functional, communication, and social skills is warranted.
Psychotherapy has not been effective.
Behavioral therapies may improve patient/family outcomes.

PITFALLS

Social deficits—not speech, language, or IQ—are the hallmarks of the disease.
Symptoms of autism—especially social isolation—may worsen on stimulants.
Subclinical seizure types, including absence spells, may be detected only on EEG.

FOLLOW-UP

Development of language in the preschool years is the best prognostic indicator. If there is no language by age 5 to 6 years, language development is unlikely and the probable outcome is poor. Prognosis is closely linked to cognitive ability and acquisition of social and communication skills; autistic children require lifelong treatment and support.

COMMON QUESTIONS AND ANSWERS

Q: What are the chances of having a second child with autism?
A: Several studies do show an increased risk of autism in families with a single case, even without any other features of a heritable cause of autism.

Q: What is the value of brain imaging in autism?
A: MRI may help diagnose a heritable syndrome with genetic counseling implications (e.g., leukodystrophy, tuberous sclerosis).

ICD-9-CM 299.0

BIBLIOGRAPHY

Edwards DR, Bristol MM. Autism: early identification and management in family practice. Am Fam Pract 1991;44(5):1755–1764.

Freeman BJ, Ritvo ER. The syndrome of autism: establishing the diagnosis and principles of management. Pediatr Ann 1984;13:284–290.

Minshew NJ, Payton JB. New perspectives in autism: Part II. The differential diagnosis and neurobiology of autism. Curr Probl Pediatr 1988;18:613–694.

Olsson I, Steffenburg S, Gilberg C. Epilepsy in autism and autisticlike conditions: a population based study. Arch Neurol 1988;45:666–668.

Piven J. The biological basis of autism. Curr Opin Neurobiol 1997;7(5):708–712.

Wing L. The autistic spectrum. Lancet 1997;350(9093):1761–1766.

Hosted by www.Geocities.ws