Dwarfism (skeletal dysplasia or short stature) is a genetic condition that results in shortened bones. There are over 200 disorders that include some form of skeletal dysplasia. Only about 20 percent of cases occur to babies born to parents who already carry the genetic mutation; 80 percent of cases occur with neither parent passing the mutation along.
A baby born with short stature will grow to an average height of 4 foot 4 inches if male, and 4 foot 1 inch if female.
The two main types of dwarfism are disproportionate and proportionate dwarfism. Most people are familiar with disproportionate dwarfism where some of the parts of the body are small or average or above-average in size. In proportionate dwarfism, all the parts of the body are small to the same degree. (Mayo Clinic)
The most common form of dwarfism is achondroplasia. It accounts for one out of every 25,000 births worldwide.
Most babies born with achondroplasia have:
- Normal life expectancy
- Normal cognitive abilities
- Moderate to marked short stature (sometimes as small as 3 feet 8 inches)
- Large heads
- Constriction of the craniocervical junction (where the skull and neck join, and where the spinal cord connects with the brain through a large hole (foramen magnum) )
- Short fingers with longer space between the middle and ring fingers
- Joint hypermobility
- Low nasal bridge and narrow nasal passages
- Enlargement of the brain (megalenephaly)
- Obstructive sleep apnea (ages 2 to 10)
- Recurrent or persistent middle ear dysfunction with hearing loss
- Kyphosis or hunching of the upper back
- Arching of the lower back (hyperlordosis)
- Limited elbow extension (only 20 to 60 degrees)
- Hypermobility of the wrists
- Knock-knees and/or bowed legs (about 60-80 percent of children)
“If one parent has achondroplasia, the infant has a 50% chance of inheriting the disorder. If both parents have the condition, the infant’s chances of being affected increase to 75%.” (MedlinePlus)
Prenatal and Post-natal Signs of Dwarfism
While many times skeletal dysplasias are diagnosed prenatally during an ultrasound, some types of dwarfism may not be detected until after the baby is born and, in some cases, not until after 2 years of age.
During an ultrasound, the doctor will take measurements of arms and legs and head. He/she will compare these numbers against normal gestational milestones. The ultrasound will also measure the amount of amniotic fluid. If there is an excess amount of amniotic fluid around the baby for the amount of gestation time, that might signify a smaller-than-average baby. If achondroplasia is suspected, confirmation will be done through chorionic villus sampling (CVS) at 11-13 weeks, or amniocentesis after 15 weeks.
At birth, a baby measuring less than 18 inches long is usually a sign that some form of skeletal dysplasia is present. Because of the larger head, it is possible that a mother will experience more bleeding. A caesarean section may be recommended to prevent this, and to reduce the chances of compression of the spinal cord and brain stem, which contributes to abnormal breathing.
What to expect in the early years?
In the days and weeks after birth, doctors will focus on confirming the diagnosis by taking a series of X-rays (CTs and MRIs) to get a better idea as to the extent of the defect, as well as measuring head circumference, body length, and body weight and plotting these measurements on a growth chart. Chest circumference will also be measured to monitor for signs of respiratory distress, which can add to the problems of craniocervical junction issues.
Approximately 2 to 5 percent of all infants with achondroplasia die unexpectedly from central apnea (loss of breathing control), which occurs when the foramen magnum opening is too narrow, compressing nerves, spinal cord, and blood vessels. This opening can be surgically enlarged in severe cases.
“Parents should be advised to use an infant seat or infant carrier that has a firm back that supports the neck and to use a rear-facing car safety seat for as long as possible. They should ... avoid use of ... mechanical swings and carrying slings to limit uncontrolled head movement.” (AAP) Umbrella strollers and Jolly Jumpers need to be avoided as well. As they grow older, children will have to avoid collision sports, vaulting, trampolining, etc.
A majority of infants and toddlers will develop recurrent or ongoing middle ear dysfunction, eventually resulting in hearing loss. If this is not treated aggressively, then delays in language and speech development will also result. Since there is no medical way of repairing the ear, equalizing pressure or ventilating tubes are placed. The first hearing tests (audiometric and tympanometric) are done “at 9-12 months of age and every 9-12 months throughout early childhood.” (Pauli)
If hydrocephaly or hydrocephalus (water on the brain) is present, a shunt may need to be placed to drain the fluid.
To avoid kyphosis (hunching of the upper back), the child will not be allowed to sit unsupported for the first 12-14 months. Emphasis will be on providing good back support, prone position activities and limiting trunk-flexed (tummy) activities. To address hyperlordosis, parents will be taught an exercise regimen to do with their child to stretch hip flexors and strengthen lower abdominal muscles, and stooping and tucking exercises.
There isn’t a cure for any form of skeletal dysplasia. Most efforts are at helping a little person adapt to his/her surroundings, or learning how to accommodate life to him or her. “Growth hormones, other drug therapies, and food or vitamin supplements are not effective in significantly increasing stature. Growth-hormone therapy may result in a transient increase in growth rate. However ... no study has clearly demonstrated a significant benefit.” (AAP)
Some families opt for limb lengthening, which is usually carried out in the teen years. It is extremely expensive, and is not performed that often in North America. Surgery may be indicated in children with bowed legs if the joints “become significantly out of plumb or if position is associated with marked pain.” (Pauli)
Because of the associated difficulties of being of small stature in a large-stature world, many accommodations may need to be made in everyday activities to help little people participate and cope with the world around them. This should be done in cooperation with parents, teachers and caregivers. The Little People of America has a wide range of adaptive technology solutions.
Darlene Oakley is a freelance writer for EmpowHER.com.
“Achrondroplasia” by Melissa Conrad Stöppler, MD. MedicineNet.com. Web. Mar 19, 2012.
Achondroplasia. MedlinePlus. Web. Mar 19, 2012.
Dwarfism: Symptoms. Mayo Clinic. Web. Mar 29, 2012.
“Health Supervision for Children with Achondroplasia” by Tracy L. Trotter, MD; Judith G. Hall, OC, MD; and the Committee on Genetics. American Academy of Pediatrics. Web. Mar 19, 2012.
“Achondroplasia: Natural History in the Infant and Young Child” by Richard M. Pauli, M.D., Ph.D., Midwest Regional Bone Dysplasia Clinics. Web. Mar 19, 2012.
Dwarfism. Shriners Hospital for Children. Web. Mar 19, 2012.
Tracy L. Trotter, MD et. al. Health Supervision of Children With Achrondronplasia. American Academy of Pediatrics. Web. Mar 19, 2012.