At least 8 percent of all preschool children (birth to 6 years) exhibit developmental delays in one or more areas. Some have global delays—they lag in all areas of development—and others lag in specific areas. Different neurodevelopmental disorders cause different types of delays. That’s why identifying a child’s pattern of delays can lead to a diagnosis. A diagnosis, in turn, offers many benefits.
When a child is diagnosed with a particular disorder, clinicians can design appropriate treatment plans. Families and clinicians will learn to expect and plan for conditions associated with the diagnosed disorder. They’ll also have an idea of the outcomes they can expect. In many cases, putting a name to a condition lessens a family’s anxieties. It also helps predict the risk of a similar condition occurring in future pregnancies.
Regarding delays, evaluation, screening, diagnosis and intervention are all important steps; each is addressed below.
Start With an Evaluation
The first step in identifying the reasons for a delay is to schedule a neurodevelopmental assessment and medical evaluation. Parents are essential during such evaluations, because they best perceive the rate at which their child is reaching developmental milestones.
When evaluating development, clinicians look for delay, dissociation and deviancy. Delay refers to a significant lag in one or more areas of development. Dissociation refers to the difference in development between two areas (one area is more delayed). Deviancy refers to achieving developmental milestones unevenly in different areas of development.
Global Delays
Children diagnosed with mental retardation often have global developmental delays. Two to three children of every 100 have some type of mental disability. Those whose IQs are 55 or below generally have physiological reasons for their delay.
Common causes of a global delay are:
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Chromosomal anomalies such as Down syndrome, the most common identifiable cause of mental retardation
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Fetal alcohol syndrome, the most common preventable reason for mental retardation
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Fragile X syndrome, the most common known cause of inherited mental retardation
Speech and Language Delays
Among children with developmental disabilities, disorders of speech and language development are the most common. Eleven percent of toddlers have a speech and language impairment.
Early identification and intervention is vital—even for mild delays. That’s because the social and educational development of children with delayed speech and language may be significantly disrupted. Children with delayed speech and language should also be evaluated for hearing loss, mental retardation and autism, a verbal learning disability and developmental language disorders
Hearing Loss
Hearing loss affects two to four of every 1,000 children. About half of preschool children have fluctuating hearing loss caused by fluid in the middle ear.
In general, the greater the hearing loss, the more language is delayed. Even when hearing loss is confined to one ear, more than one-third of such children fail at least one grade in school. The earlier the hearing loss is identified, however, the better the outcome.
Autism
Autism is a relatively common disorder, occurring approximately once in 500 children.
Because social and emotional abilities, cognitive development and language are closely related, it’s important to review any dissociation among them and in comparison to motor skills. Children whose speech and language skills lag and whose behaviors resemble autism should be evaluated for Asperger syndrome, childhood disintegrative disorder and Rett syndrome.
Verbal Learning Disability
Children with a verbal learning disability—similar to children with severe mental retardation or autism—often show dissociation in developmental areas. For example, their language may be more delayed than their motor skills. In addition, a verbal learning disability may be present if a child’s academic achievement at school doesn’t reflect the child’s general intellectual abilities.
Developmental Language Disorders
A developmental language disorder is characterized by speech that begins late and advances slowly. Children with a developmental language disorder (about 10 percent of the population) have a gap between their cognitive abilities and their language skills.
Motor Delays
Motor delays can occur in such skills as crawling, walking and grasping. Motor delays that appear between the ages of 6 and 18 months are often a sign of neurological problems.
When a child has a motor delay and delays in other developmental areas, clinicians should check for a visual impairment or mental disability. When a child has only, or primarily, motor delays, clinicians should consider cerebral palsy, ataxia, spina bifida, spinal muscular atrophy and myopathy. If there’s no motor delay, however, a child does not have cerebral palsy.
Older children with motor skills substantially below their cognitive abilities may have a development coordination disorder. Their clumsiness may be associated with a learning disability or attention deficit/hyperactivity disorder.
Hypotonia
Hypotonia, or “floppy muscles,” is the most common symptom of motor problems in newborns and infants. Such children show developmental delays. A neurodevelopmental examination should include a discussion of the quality of the pregnancy (including onset and vitality of fetal movements), any problems during labor and delivery, and family history (to assess the potential for genetic disorders).
The challenge in diagnosing hypotonia lies in differentiating the reasons for it. Weakness strongly implies a neuromuscular condition. Normal or increased deep tendon reflexes suggest central hypotonia.
Fine Motor Delays
Children with fine motor delays and delays in other areas should be evaluated for visual impairments and mental disabilities. It’s imperative for clinicians to assess the eyes and visual acuity of children with delayed fine-motor skills. It’s never too early to do so.
If a delay occurs primarily in one developmental area, clinicians should consider hemiplegia, a brachial plexus injury (such as Erb’s or Klumpke’s palsy) or a fractured clavicle. In older preschool or elementary school children with fine-motor delays, consider a developmental coordination disorder or a disorder of written expression. About 6 percent of all children have developmental coordination disorder. It’s often associated with attention deficit/hyperactivity disorder and learning disabilities.
Personality and Social Delays
When a child’s personality and social skills show delays, it’s important to consider the child’s cognitive abilities, potential for autism and environment. (For example, abuse, neglect, deprivation and other less-than-ideal family dynamics can affect personality and social skills.)
Certain behaviors, combined with severe communication disorders, suggest autism. To diagnose autism, it’s important to observe whether the child shows restricted and repetitive behaviors (such as sustained odd play). Children with social interaction disorders (such as difficulties playing with others in an age-appropriate way) may also have autism.
In contrast, a child who fails to discriminate between familiar and unfamiliar persons—and respond differently—may have a reactive-attachment disorder. Discriminating sociability usually emerges between 2 and 7 months of age. A dissociation among social skills, expressive language and language comprehension skills may help determine a diagnosis.
Screening Tools
Developmental screenings or assessments are essential in all practices. Many pediatricians use the Denver II test. This test, however, may not detect cerebral palsy in a child’s first 12 months. In general, it consistently over-refers or under-detects. Measures that rely on parents’ reports include the Parents’ Evaluation of Developmental Status, the Ages and Stages Questionnaire, and the Child Development Inventories. Office checklists aren’t recommended, because they often miss developmental or behavioral concerns.
Screening instruments should never take the place of a thorough neurodevelopmental history and physical examination. Developmental delays are symptoms, not diagnoses. Listening to parents, paying special attention to their concerns and meticulously charting a child’s history are vital to making a neurodevelopmental diagnosis.
Intervention
It’s essential to help families plan how to address a child’s developmental delays. Seek resources in the patient’s hometown, if possible, and further away if necessary. Early intervention services, available through the school district, are a sound first start.
Although eligibility criteria vary, common measures of delay are 25 percent and/or two standard deviations in one or more developmental areas. A neurodevelopmental assessment is essential to help families get the support services they need.
Raymond Tervo, M.D. is a neurodevelopmental pediatrician for Gillette Children’s Specialty Healthcare in St. Paul, Minnesota.
