Diagnosing Developmental Disabilities

Developmental disabilities are defined in terms of what an individual can or
cannot do rather than in terms of a clinical diagnosis. They affect the typical
processes in a child’s growth, particularly the maturation of the central nervous
system. For this reason, early identification is important. The potential
exists for an improved outcome if children are provided with education and
habilitation. Prenatal diagnostic techniques may be appropriate for at-risk
pregnancies. If a fetus is known to be affected, the physician is better able to
plan the delivery and for special care during the newborn period.

Newborn screening is another way in which to identify conditions that
can result in developmental disabilities if untreated. The Apgar test is administered by the medical staff in the delivery room at one minute, five minutes,
and, if there are complications, at ten and fifteen minutes after birth. It
measures the effects of various complications of labor and birth and determines
the need for resuscitation. The test assesses physical responsiveness,
development, and overall state of health using a scale of five items rated
from 0 to 2. A low Apgar score at birth can signal the potential for a developmental
disability.

Measurement of head circumference is a useful tool for predicting
whether an infant is likely to have a neurodevelopmental impairment such
as microcephaly. A blood test screening can be done for phenylketonuria
(PKU), congenital hypothyroidism, galactosemia, maple syrup urine disease,
homocystinuria, and biotinidase deficiency. Early detection of these
conditions and appropriate intervention may reduce the severity of the resulting
disability.

An older child can be referred to a developmental pediatrician for assessment
of a developmental disability if the child has not attained expected
age-appropriate developmental milestones, exhibits atypical development
or behavior, or regresses to a previous level of development. Correcting for
prematurity in developmental testing is necessary. An instrument commonly
used is the Denver Developmental Screening Test. The more severely
affected a child is, the clearer is the diagnosis, as an individual’s failure to
meet developmental milestones may represent a short-term problem that resolves over time as the child “catches up.” Even readily identifiable indicators
of potential disability do not always result in expected delays.
Related issues such as feeding, elimination, and cardiorespiratory problems;
pressure sores; and infection control are also considered as part of the
diagnosis. Screening for lead poisoning or psychological testing may be recommended.

At whatever age the person is referred, a multidisciplinary evaluation attempts
to establish a baseline of the present level of performance, including
both skills and deficits. Activities of daily living (ADLs) such as bathing, eating,
and dressing are widely used in assessing this population. Needing assistance
with ADLs becomes an important criterion for determining eligibility
for public and private disability benefits. An appraisal is made of those deficits
that can be remedied and those that require accommodation. The predictive
accuracy of the diagnosis improves with the individual’s age.
Language development is another predictor variable. Individuals with
developmental disabilities may have little or no apparent intent to communicate
and may not understand that they can affect their environment
through communication. Though developmental disabilities, by definition,
are severe, it is possible that a child not previously identified could be detected
by routine public school prekindergarten screening.