More than 6.5 million U.S. children have diagnosed disabilities and receive special education services.1 In addition, 17% of the U.S. pediatric population is at risk for developmental delay.2
The first 2 years of a child's life represent a critical time for early intervention. Intelligence is believed to be 50% developed by age 5. The Centers for Disease Control and Prevention estimate that more than 300,000 U.S. residents younger than 21 have such poor cognitive development they are considered retarded.3 In many cases, this progression could be prevented by early intervention.3
Risk factors for developmental delay include poverty, maternal substance abuse, lack of prenatal care, low birth weight, prematurity, lack of parenting skills, abuse and neglect and medical conditions such as hypotonia. Obviously this is not a complete list. With the support of nurse practitioners and early intervention services, these risks can be decreased.
Early intervention services provide an excellent return on taxpayer funds, with a potential return of $7 for every $1 invested.4 Societal benefits of having fewer children with developmental delays include higher graduation rates, decreased grade repetition and more self-sufficient adults.4 Early intervention services provide early identification, screening and assessment. They include family training; counseling; home visits, including respite care; occupational, physical, speech and audiology services; case management for service coordination; and needed medical services. All infants and toddlers with diagnosed developmental disabilities are eligible for early intervention. States have the option to extend early intervention to children considered at risk - for example, very low birth weight infants and children from multirisk families.
What Is Hypotonia?
Hypotonia is a disability characterized by decreased muscle tone with varying degrees of floppiness. It is associated with multiple neuromuscular, metabolic and genetic disorders. Hypotonia affects many areas of a child's life, including cognitive development. The severity and progression of hypotonia varies with each child and his or her underlying diagnosis.
Developmental delay is common with many disabilities. An important distinction in hypotonia is progression. For example, Down syndrome causes low tone that is stable or nonprogressive, but muscular dystrophy causes tone problems that tend to worsen with time. Infants born prematurely may have hypotonia that improves with maturity of the central nervous system in the absence of cerebral palsy. Table 1 lists a few of the many causes of hypotonia.
|Causes of Hypotonia |
This list is not all-inclusive.
|| Chromosomal disorders or malformations|
|| Infectious causes such as toxoplasma, rubella, cytomegalovirus, herpes simplex or HIV|
|| Perinatal asphyxia, Down syndrome|
|| Congenital hypothyroidism, kernicterus |
|| Hypotonic cerebral palsy|
|| Spinal cord disorders, hydrocephalus|
|| Neonatal myasthenia gravis, botulism|
|| Prader-Willi syndrome, congenital myopathies (after neonatal period)|
When I began researching benign congenital hypotonia (BCH) in 1992, I found one paragraph. At that time it was called Oppenheim's disease. Now there are two classifications for it: congenital hypotonia (779.89) and benign congenital hypotonia (358.8). The difference between the two is that the cause of BCH is not known.5 Another unknown is the exact number of children affected. The estimated prevalence of all types of congenital hypotonia, including hypotonic cerebral palsy, is one in 1,000 births. When hypotonia in premature infants weighing less than 1,500 grams is included, the prevalence is 60 per 1,000 births.5
Benign congenital hypotonia is considered benign because it is not fatal and the condition does not worsen like many neuromuscular disorders. It does, however, have the potential to affect lifelong physical, cognitive, social and emotional development.
BCH is a diagnosis of exclusion and is frequently applied to children with nonprogressive low tone without a known cause. Unlike other neuromuscular disorders, BCH does not worsen and tends to improve with maturation of the central nervous system and early intervention. Children with this disorder do not receive the correct "signals" for all their muscles to work properly. Thus, muscle biopsy and neuromuscular testing usually produce normal results.
The cause of BCH is unknown, but it is believed to be an autosomal recessive trait, meaning that both parents must contribute a gene for this disorder to occur. No genetic testing is available, and no cure has been developed. Many affected families report pregnancy or delivery complications, decreased fetal movement, prolonged hospital stays, breastfeeding difficulty, maternal age over 30, or a family history of developmental delays and hip dysplasia. No tests are available for prenatal diagnosis. Treatment is supportive for both the child and family.
Signs and Symptoms
The infant with BCH feels limp and fragile and has very flexible joints. He or she easily falls sideways and slides out of openings on high chairs and strollers. An affected baby may not develop head control until quite late and often sleeps in a "frog-leg" position with hips externally rotated. Children with hypotonia are prone to skeletal deformities as a result of maintaining abnormal postures. Table 2 summarizes signs and symptoms of BCH.
|Signs and Symptoms|
|| Unable to maintain head control or sitting position|
|| Feeding difficulties|
|| Orthopedic problems|
|| Developmental and cognitive delay|
|| A passive onlooker rather than participant|
|| Speech delay due to facial muscle weakness|
|| Perceived to have low cognitive function|
The typical child with hypotonia is described as a "good, quiet baby" who needs to be awakened to feed, does not nurse well and is generally content. Parents carry the child with BCH like a young infant and lay him or her flat for dressing; the child becomes a passive onlooker. Parents may discourage the child from learning self-help skills such as dressing and feeding because the tasks are so time consuming for him or her. The infant with hypotonia is unable to reach out and mouth toys and becomes used to having someone entertain, feed and change him or her. The child may not receive necessary stimulation, which contributes to developmental delay.
The child's low tone often encompasses the face and mouth, making sucking, chewing and swallowing challenging. Food aversions and vomiting due to choking episodes are common. Food and saliva may be drooled out of the mouth, persisting as late as grade school and affecting socialization. Some children appear to be less intelligent owing to decreased smiling, verbal and nonverbal communication. Language development is often significantly delayed and the progression to solid foods is slow. Affected children have gaps in receptive and expressive language development. Global developmental delays are common as a result of the child's inability to explore the environment and bring toys to the mouth.
Congenitally dislocated hips and clubfeet are common in this population. After birth, children with BCH may develop pectus excavatum from adapted trunk control patterns and muscle weakness. Continued low tone in the pelvis causes the young child to lean forward dramatically to sit. Affected children often sit on their forelegs with their feet behind them (known as the "W sit"), leading to further hip and knee problems. A common motor pattern is the "combat crawl." In this pattern, the child uses his or her forearms to propel forward and drags his or her legs behind him (think of soldiers crawling under barbed wire fences).