| Fetal Alcohol Syndrome
Introduction
Background: Adverse neonatal and pediatric effects occur with maternal alcohol consumption during pregnancy. Fetal alcohol syndrome (FAS) is contingent on findings in the following 3 areas: (1) dysmorphology (particularly midfacial anomalies), (2) growth retardation (intrauterine growth rate and failure to experience catch-up growth), and (3) CNS involvement (cognitive impairment, learning disabilities, impulsiveness).
Effects of alcohol exhibited by exposed children exist on a diagnostic continuum, with FAS the most involved form and fetal alcohol effects (FAE) on the less affected end of the continuum. Children with FAE may exhibit little or no dysmorphology but display significant CNS involvement.
FAS first was described in France in 1968 by Lemoine et al and in the United States in 1973 by Jones and Smith. Prominence within the literature is attributed to the following causes: (1) FAS is the leading known cause of mental retardation, (2) FAS or FAE produces irreversible physical and mental damage, and (3) FAS crosses all socioeconomic groups and affects all races. The costs for one child with FAS are estimated to be $2 million over a lifetime, and costs of FAS to the American taxpayer are more than $321 million each year.
Pathophysiology: Alcohol crosses the placenta and rapidly reaches the fetus. Extensive studies have demonstrated equivalent fetal and maternal alcohol concentrations, suggesting an unimpeded bidirectional movement of alcohol between the 2 compartments. The fetus appears to depend on maternal hepatic detoxification, because the activity of alcohol dehydrogenase in the fetal liver is less than 10% of that observed in the adult liver. Furthermore, the amniotic fluid acts as a reservoir for alcohol, resulting in prolonged fetal exposure.
The mechanism for the spectrum of adverse effects on virtually all organ systems of the developing fetus is unknown. Ethanol and its metabolite acetaldehyde can alter fetal development by disrupting cellular differentiation and growth, disrupting DNA and protein synthesis, and inhibiting cell migration. Both ethanol and acetaldehyde modify the intermediary metabolism of carbohydrates, proteins, and fats. Both also have been demonstrated to decrease the transfer of amino acids, glucose, folic acid, zinc, and other nutrients across the placental barrier, indirectly affecting fetal growth via intrauterine nutrient deprivation. Elevated levels of erythropoietin in cord blood of newborns exposed to alcohol have been reported and suggest a state of chronic fetal hypoxia.
Frequency:
- In the US : Incidence of FAS is 1-2 infants per 1000 live births. Incidence is related to the population studied. Assuming an annual birth cohort of approximately 4 million, this translates into 2,000-12,000 FAS births per year. Incidence among children born to heavy drinkers is approximately 4%.
Mortality/Morbidity:
- A number of adverse effects on the outcome of pregnancy have been noted with chronic alcohol use, including spontaneous abortion, placental abruption, preterm delivery, amnionitis, and stillbirth.
- Morbidity and mortality associated with FAS are difficult to specify because of manifestations that are not associated solely with FAS or FAE, lack of a single biologic marker, and unreliable maternal drinking histories during pregnancy. Polysubstance abuse also creates difficulty in isolating the consequences of maternal alcohol consumption.
- Alcohol-related birth defects and neurodevelopmental disorders are 2 categories of abnormalities observed in individuals with FAS. They may co-occur and range from subtle to severe.
Race: FAS effects all races.
Clinical
History: A documented history of exposure to alcohol is not required for the diagnosis of FAS. Based on the history obtained, the following 3 diagnostic subcategories are described in the literature.
- FAS with a history of maternal alcohol exposure
- Confirmed maternal alcohol exposure exists.
- Evidence exists of characteristic pattern of facial anomalies.
- Evidence of CNS neurodevelopment abnormalities is present.
- FAS without confirmed maternal alcohol
- Evidence exists of characteristic pattern of facial anomalies.
- Evidence of CNS neurodevelopment abnormalities is present.
- Partial FAS with confirmed maternal alcohol exposure
- This category is useful for the patient who presents for diagnosis as an older child or adolescent. The natural history of persons with FAS is such that some of the hallmark indicators used in infancy are not maintained into adolescence.
- Evidence of some components of the pattern of characteristic facial anomalies is present.
- The individual displays evidence of growth retardation or CNS neurodevelopmental abnormalities or evidence of a complex pattern of behavior or cognitive abnormalities that are inconsistent with developmental level and cannot be explained by familial background or environment alone.
Physical: Alcohol withdrawal is uncommon. Infants of women who have been drinking immediately before delivery may have alcohol on their breath for several hours, and blood levels of these infants are similar to those in the mother. Hypoglycemia and acidosis may be present. Withdrawal symptoms are agitation, hyperactivity, and marked tremors lasting 72 hours, followed by approximately 48 hours of lethargy. Seizures may develop. In addition, the following physical findings may manifest in all organ systems:
- Craniofacial abnormalities
- Midface hypoplasia
- Flat philtrum
- Retrognathia in infancy; micrognathia or relative prognathism in adolescence
- Low nasal bridge
- Thin upper lip
- Microphthalmia, strabismus, ptosis
- Short palpebral fissures
- Cleft palate
- Posterior rotation of the ears
- Central nervous system and neurobehavior anomalies
- Microcephaly
- Intellectual impairment (mild to moderate retardation), low intelligence quotient (IQ of 65-70)
- Hypotonia
- Developmental delay
- Poor coordination
- Cognitive impairment
- Sensory impairment
- Irritability in infancy, and hyperactivity in childhood or attention deficit/hyperactivity disorder (ADHD)
- Language impairment
- Sleep/wake cycle disturbances
- Seizure disorder
- Delayed or deficient myelination
- Corpus callosum agenesis or hypoplasia
- Electroencephalogram hypersynchrony
- Echolalia
- Cerebral palsy
- Ventricular and atrial septal defects
- Tetralogy of Fallot
- Great vessel anomalies
- Double outlet right ventricle
- Dextrocardia
- Patent ductus arteriosus
- Hydronephrosis
- Renal dysplasia, aplasia, small rotated kidneys
- Hypospadias
- Ureteral duplication, megaloureter,
- Cystic diverticula
- Vesicovaginal fistula
- Pyelonephritis
- Horseshoe kidneys
- Gastrointestinal
- Inguinal and abdominal hernias
- Diastasis recti
- Gastroschisis
- Extrahepatic biliary atresia
- Shortened fifth digits
- Radioulnar synostosis
- Flexion contractures
- Camptodactyly
- Clinodactyly
- Pectus excavatum and carinatum
- Klippel-Feil syndrome
- Hemivertebrae
- Scoliosis
- Dislocated hip
- Lumbosacral lipoma
- Strabismus
- Oculo-retinal tortuosity
- Ptosis
- Epicanthic folds
- Blepharophimosis
- Short-palpebral fissures
- Microphthalmia, steep corneal curvature, anterior chamber anomalies
- Refractive problems secondary to small globes (eg, myopia, astigmatism)
- Cataracts
- Glaucoma
- Retinal coloboma
- Intermittent conductive hearing loss secondary to recurrent serous otitis media
- Neurosensory hearing loss
- Delayed maturation of the auditory system
- Central hearing loss
- Poorly formed conchae and rotation of the ear
- Eustachian tube dysfunction
- Microtia
- Hypoplastic nails
- Hemangiomas
- Hirsutism in infancy
- Aberrant fingerprint and palmar creases
- Disproportionately diminished adipose tissue
- Abnormal whorls on scalp
- Association with neoplasm
- Neuroblastoma
- Adrenal carcinoma
- Hepatoblastoma
- Ganglioneuroblastoma
- Endodermal sinus tumor
- Acute lymphocytic leukemia
- Sacrococcygeal teratoma
- Medulloblastoma
- Hodgkin disease
- Other anomalies
- Pectus excavatum
- Bifid xiphoid
- Pulmonary atresia
- Atelectasis
- Upper respiratory infections
- DiGeorge syndrome
Causes:
- Maternal alcohol consumption
- The current evidence supports the conclusion that women who drink heavily during pregnancy may produce children exhibiting features of FAS.
- Low-to-moderate levels of maternal alcohol consumption have not been demonstrated consistently to cause harm to the fetus or the child.
- In the absence of a scientifically established threshold of consumption above which risk to the fetus is present, no consistent and valid safe level of alcohol consumption exists.
- A number of studies demonstrate that the risk of congenital abnormalities resulting from prenatal alcohol exposure increases in a dose-dependent fashion.
- Maternal conditions and characteristics
- Maternal conditions and characteristics affect the likelihood of producing a child with FAS.
- The longer a woman drinks, the more likely she is to give birth to a child with FAS or multiple congenital anomalies associated with alcohol use.
- Prolonged maternal alcohol consumption adversely affects the woman's general health status, increasing the risk of illness and depleting maternal nutritional stores.
- Pregnancy naturally places stress on the body, resulting in increased workload and metabolic rate.
- Pregnancy increases the blood volume and makes the cardiac, hepatic, and renal systems work harder.
- These, coupled with a lack of maternal nutritional stores, further can deplete maternal nutritional status.
- When repeated pregnancies coexist with little or no prenatal care, nutritional deficits, and heavy drinking, the risk of giving birth to a child with FAS is increased.
- Having one child with FAS further increases the risk of producing subsequent children affected with FAS.
- The typical biologic mother of a child with FAS is older than 30 years, has a long-standing history of heavy drinking, and has had several pregnancies.
- Cleft lip with or without cleft palate
- Cleft lip with or without cleft palate can result from teratogenic exposure, can be part of FAS, can be inherited as a multifactorial disorder, or can be part of an autosomal dominant, autosomal recessive, or X-linked condition.
- In all, more than 50 syndromes are associated with cleft lip.
- Physical examination reveals whether any dysmorphic features or malformations suggestive of such a syndrome are present.
- Isolated cleft lip, with or without cleft palate, is considered a multifactorial disorder, resulting from the effects of genetic liability and environmental factors that often cannot be identified.
- Most children with FAS have developmental delay in the maturation of the auditory system, intermittent conductive hearing loss secondary to recurrent serous otitis media, sensorineural hearing loss, or central hearing disorders.
- Delayed development may reflect impaired maturation of neurons, myelin, or synapses.
- Recurrent serous otitis media has been attributed to malformations of the eustachian tube or immune system.
- Sensorineural hearing loss is most likely the result of increased cell death in the embryonic inner ear, resulting in reduced numbers of sensory receptor cells and auditory nerve fibers.
- Central hearing disorders are observed with anomalies of various brainstem and forebrain structures involved in auditory processing.
- A child with hearing loss experiences impaired speech and language acquisition and comprehension and most likely exhibits hyperactivity and distractibility
The medical care of the child with FAS or FAE is treatment for associated birth defects. Treatment often includes hospitalization in a neonatal intensive care unit, neonatal auditory screening and follow-up evaluations, treatment for serous otitis media, and hearing aids. Arrange special education services, speech therapy, day care, and home respite care. Surgical care is recommended for malformations that can be corrected surgically. Obtain consultation from various pediatric subspecialists including nutritionists, physical therapists, and speech therapists
|
Medical online consultation with qualified doctors
Copyright © 2004-2005