Early Childhood Education

Developmental Disorders of Infancy and Early Childhood, A Taxonomy of

The following listing briefly describes a range of conditions that can affect young children. It should be noted that the perception of disability is a social phenomenon, and that the capacities of an individual child are affected by typical developmental processes, a variety of environmental influences, and biological risk factors. These labels are just that, labels that describe conditions but fail to adequately portray the unique personhood of each child. This taxonomy is organized by underlying conditions rather than by functional categories or environmental risk factors (e.g., lead poisoning, fetal drug, or alcohol exposure). It is intended to provide an overview. For specific diagnostic criteria consult Diagnostic and Statistics Manual of Mental Disorders (DSM IV) or the Diagnostic Classification of Mental Health and Developmental Disorders of Infancy and Early Childhood. When working with children more detailed information on these conditions is required and should be used in concert with assessment of the child’s individual strengths and needs as they relate to parental concerns, developmental domains and real world skills.

Sensory Disorders

Hearing impairment. Hearing impairment ranges from mild hearing loss to deafness which is defined as the level of hearing loss at which speech cannot be understood. Conductive hearing loss involves problems with the middle or outer ear often caused by infections such as otitis media. Sensorineural hearing loss occurs in the inner ear or auditory nerve and is typically more debilitating than conductive loss.

Visual impairment. Children with a variety of developmental disabilities are at greater risk for visual impairments such as amblyopia (lazy eye), strabismus—an imbalance of the eye muscles, and cataracts—opacity in the lens, as well as more normative conditions like myopia. A number of diseases can cause blindness that can severely affect other areas of development. Retrolental fibroplasia has been related to the use of high does of oxygen to premature infants.

Sensorimotor integration disorders. This set of conditions affects a child’s ability to integrate sensory input including that from vestibular and proprioceptive systems. Tactile defensiveness is an inability to tolerate textures, touch, or stimulation.

Neuromotor Disorders

Cerebral palsy. Cerebral palsy results from brain lesions that result in mild to severe motor problems. A variety of prenatal and perinatal events (e.g., anoxia, RH blood incompatibility, birth complications, and heavy alcohol use) can contribute to the brain damage. Depending upon the location and nature of the lesion upper and lower limbs and sides of the body may or may not be affected.

Spina bifida. Spina bifida results from neural tube defects that interrupt transmission of neural impulses and motor development to the lower part of the body. Due to new surgical techniques the neural openings can now be corrected, limiting the motor disabilities as well as the accumulation of spinal fluid in the brain’s ventricles that has the potential to affect cognitive functioning.

Muscular dystrophy. Muscular dystrophy, as opposed to cerebral palsy, is a progressive disorder resulting from a brain lesion. Its mechanisms are less well understood but are linked to a genetically transmitted metabolic disorder. The most common form is Duchenne’s, which results in gradual disintegration of muscle cells.

Seizure disorders. Seizure disorders constitute a variety of conditions resulting from abnormal bursts of electrical activity that disrupt brain functioning. Grand mal seizures usually involve a loss of consciousness and alternate rigidity and relaxation of muscles. Focal seizures involve localized areas of the brain. Myoclonic seizures do not result in loss of consciousness and are characterized by involuntary jerking of the extremities. Akintetic seizures are opposite myoclonic in that they involve reduced muscle tone. Petit mal seizures are of short duration involving a brief lapse of consciousness without loss of muscle tone. Seizure disorders are often associated with other neurological disorders.

Congenital disorders. Only the most common of many hundreds of congenital disorders are described here.

Genetic Metabolic Disorders

Phenylketonuria is a metabolic disorder that, if left untreated, can cause brain damage and severe mental retardation. It can be identified with routine blood and urine screening at birth. Cystic fibrosis is also a metabolic disorder that leads to buildup of mucus in the child’s lungs and vulnerability to infections. Death usually occurs by early adulthood. Galactosemia results in an enlarged liver. Children are susceptible to mental retardation, cataracts, and infections. Congenital hyperthyroidism is a hormone deficiency which, if left untreated, leads to floppy muscle tone and retardation. Tay-Sachs disease is a progressive disease of the nervous system that affects infants after about six months of age and leads to severe debilitation and death by age 5.

Chromosomal Disorders

Down syndrome involves mild to severe mental retardation, low muscle tone, and distinctive physical features. In many cases cardiovascular problems are also present. Cri du chat syndrome results in microcephaly, smaller than average size, poorly formed ears. Children are usually mentally retarded. Prader-Willi syndrome results in moderate retardation, obesity, and low muscle tone. Fragile- X disease often results in retardation and behavioral disorders.

Cognitive/Learning Disorders

Mental retardation. Mental retardation is defined as significantly subaverage general intellectual functioning and can be attributed to a broad variety of both biological and environmental factors. Classification is typically arranged by IQ, with IQs of 50/55-70 being considered mild, 35/40-50/55 moderate, 20/25- 35/40 severe, and below 20 or unspecified as profound. Labeling also requires evidence of limits on adaptive behavior. Typically in infancy and early childhood developmental delay is referred to, particularly in mild to moderate cases, based on measures of overall developmental functioning to avoid false prediction of retardation as well as stigma.

Learning disabilities. Learning disabilities can affect children of average or above average intelligence. They are characterized by specific inabilities in auditory and visual processes and are rarely diagnosed before school age. There is some evidence that premature and low birth weight babies have a higher incidence of learning disabilities when they reach school age.

Attention deficit disorder. Attention deficit disorder can be categorized in two ways, either with (ADHD) or without (ADD) hyperactivity. The two classifications are characterized by inattention, impulsivity and, in the case of ADHD, by a high activity level.

Social/Emotional Disorders

As with language, these social and emotional disorders may be secondary to other conditions. For example, self-stimulation and self-injurious behavior may characterize the behavior of some children with mental retardation, or social adjustment to a neuromuscular disorder may result in extreme shyness or oppositional behavior. On the other hand, a social-emotional disorder may be a primary disability with an etiology of its own.

Autism. Autism and an associated classification, pervasive developmental disorder, are characterized by severe delays of communicative and social development. Autistic children often engage in repetitive and self-stimulatory behavior and inability to tolerate even small changes in their environment or schedule. Autistic children show abroad range of intelligence and adaptive abilities. Some evidence exists for physiological causes but it is not yet conclusive.

Attachment disorders. Attachment disorders are characterized by behaviors that indicate the lack of a strong emotional tie to a caregiver or caregivers. Such children are seen as avoidant or resistant to forming relationships. These disorders are seen as primarily induced by severe child maltreatment confinement to nonresponsive institutional care.

Behavior disorders. Oppositional and aggressive behaviors in young children are increasing. Typically the child’s social environment (e.g., abusive, neglectful, or nonnurturant situations) has been blamed for these behaviors. However, the factors that enter into the equation that result in such disorders may be biophysical and temperamental as well as environmental. Increasingly, a portion of these children are being diagnosed with ADD/ADHD.

Social withdrawal/isolation. Some children are extremely fearful or withdrawn in social situations. Again, a variety of factors, both biological and environmental, can lead to these conditions. Conditions such as social phobias or selective mutism may be identified in the preschool years.

Communication Disorders

Speech and language disability is often associated with many of the other conditions listed here such as retardation, hearing problems, or autism. In some cases, however, language functions seem to be the primary issue of concern. Because of the importance of language functions in development, this primarily functional area is included as a distinct disability category.

Speech or phonological disorders. Speech and phonological disorders involve difficulties with the production of speech sounds. These often include problems with the nerves and muscles of the mouth, vocal cords, and breathing apparatus.

Expressive language disorders. Expressive language disorders are, in some cases, the result of lesions in the motor cortex responsible for language production. They can also be the by-product of a number of other biological and environmental risk factors. They are characterized by difficulty in using words.

Receptive language disorders. Receptive language disorders are those that affect the comprehension and production of language. Receptive aphasias involve damage to temporal language areas. As a result, not only language comprehension but also language production is affected. The understanding and production of language involves a broad set of abilities and hence these problems require assessment that isolates specific areas of skill.

Health-Related Conditions

Failure to thrive. The failure to gain weight within a normal range may be due to a number of factors that may include either an inability to provide sufficient breast milk or digestive problems in the infant. In some instances it has been related to neglect or ignorance of basic parenting practices.

Infections. The incidence of rubella is now rare, but in the past German measles during pregnancy resulted in children with sensory and cognitive impairments. Other viral infections such as cytomegalovirus and herpes simplex can cause severe disabilities. Meningitis , an infection of the tissue around the brain and spinal cord, can be due to a virus or bacterial infection and can cause a wide range of neurological problems.

Gastrointestinal. Many children with multiple or severe conditions have difficulty maintaining body weight and meeting basic nutritional needs. In addition they may also have gastroesphageal reflux, a condition in which the muscle that prevents food from backing up between the stomach and esophagus is weak. See also Attention Deficit Disorder/Attention Deficit Hyperactivity Disorder; Autism; Cerebral Palsy; Fetal Alcohol Syndrome.

Further Readings: Blackman, J. A., ed. (1983). Medical aspects of developmental disabilities in children birth to three: A resource for special-service providers in the educational setting. Iowa City: University of Iowa Press; Neisworth J. T., and S. J. Bagnato (1987). The young exceptional child: Early development and education. New York: Macmillan; Widerstrom, A. H., B. A. Mowder, and S. R. Sandall (1991). At-risk and handicapped newborns and infants: Development, assessment, and intervention. Englewood Cliffs, NJ: Prentice-Hall.

John Hornstein