Prader-Willi Syndrome (PWS)
Prader-Willi syndrome (PWS) is a rare genetic disorder, affecting 1 in 10,000 to 1 in 30,000 babies born. It is, however, the most common genetic cause of severe obesity.
Babies with PWS may kick less than normal while in the womb. They often are born past their due date and require a C-section delivery. Newborns typically show very low muscle tone and are often described as “floppy.” They might have difficulty breathing and may need extra oxygen or have difficulty eating and seem too weak to breastfeed or drink from a bottle. Such breathing and feeding issues usually delay a baby from going home from the hospital by weeks or even months.
Later developmental milestones such as sitting, standing, and walking are significantly delayed. Children with PWS do not start walking, on average, until they are 27 to 29 months old. With the early use of growth hormone medication, though, children start to walk in about 18 months.
The syndrome also impacts a significant number of bone and skeletal issues that should be evaluated as soon as they are identified so that early interventions can improve balance and motor abilities.
Babies and children diagnosed with Prader-Willi syndrome (PWS) need a comprehensive, multi-disciplinary approach to address the wide range of symptoms that occur with this rare genetic metabolic disorder.
At SSM Health Cardinal Glennon Children’s Hospital, pediatric specialists in endocrinology, gastroenterology, orthopedics, and behavior and development have extensive expertise and collaborate on the care of children diagnosed with PWS.
Eating & Gastrointestinal Issues
Eating difficulties and digestive disorders are common in infants and children with PWS. The earliest symptom that can occur soon after birth is difficulty in suckling. They may also experience food aspiration (food accidentally running down the windpipe rather than to the stomach), which can cause dangerous lung infections. By the time children are between 2 and 4 years of age, they can develop uncontrolled cravings for food. In addition, they can experience constipation, heartburn, acid reflux, and bloating. People with PWS usually have a high pain threshold, and do not experience or complain about their digestive issues until they are serious, which is why it is important to begin good eating habits early and watch for any signs of difficulty. Children with PWS rarely vomit and are always hungry, so danger signs are when they do vomit, show no interest in food, or have painful swelling and bloating of their abdomen, all of which should be evaluated in a hospital emergency room.
One of the more serious concerns is gastroparesis, a condition where the food does not move from the stomach into the small intestines properly. This can happen after an illness or from overeating. It may lead to thinning of the stomach lining and wall and, in extreme cases, a stomach rupture, which is a life-threatening situation. Research has found that gastroparesis occurs in an estimated 20% of young adolescents (ages 11 to 15) but can occur at earlier ages and also in adulthood.
At SSM Health Cardinal Glennon, pediatric gastroenterologists will collaborate with dietitians/nutritionists to help parents and children develop a regular meal schedule, maintain healthy diet habits, and control access to food. Regular physical activity also is recommended.
Growth Hormone & Other Hormone Deficiencies
People with PWS have abnormal functioning of the hypothalamus and the pituitary gland, small but very important parts of the brain that control body temperature, blood pressure, heart rate, breathing ability, sleep, and hunger and thirst, among several other functions. The result of the abnormal function is reduced levels of growth hormone, which is important for proper metabolism. Growth hormone medication has proven to be effective in many cases, resulting in improved growth, reduced obesity, and better breathing function. These treatments usually begin in early childhood — sometimes as early as six months of age — and continue until the child becomes an adult. Other hormonal therapies also may be prescribed.
Orthopedic Problems
Five orthopedic issues are noted in children with PWS:
Poor muscle tone, also called hypotonia, is usually detected at birth or in early infancy, but can also be suspected when there is little movement of the baby while in the womb. Once born, infants may seem limp or “floppy,” with little to no head control. Parents also may notice suckling difficulties while feeding and delays in sitting up or crawling as children age. It is important to begin physical therapy early to help babies with PWS gain strength. As they get stronger, they may benefit from temporary braces for their legs to help support them as they try to stand and walk.
Common in children with PWS, flat feet are typically the result of overly flexible ligaments and poor muscle tone. The heels roll to the outside of the ankles, the front of the foot points further out to the side, and the arch on the inner side of the foot might collapse. This can lead to poor balance, chronic fatigue in legs and feet, and trouble walking and running. Parents may see their children have a wide stance while standing or walking. The foot shape may affect the child’s posture, where they are less upright and walk in a “guarded” hands-forward manner. More importantly, it might cause a child to be less active than they normally would be, and may lead to foot pain as adults. The best solution is a small brace within the shoe to help correct the heel position.
Both children and adults with PWS may have decreased bone strength. This can lead to fractures or complicate healing after a bone surgery, such as a spinal fusion. Growth hormone replacement therapy improves bone health. Most children will also benefit from vitamin D and calcium supplements. It is important to recognize the high pain threshold of people with PWS; there are many examples of children continuing to walk on broken legs, for example. Any change in the use of an arm or leg, especially after a fall, should be carefully evaluated to make sure there is no fracture.
Problems in the hip joint can occur when the hip socket develops abnormally and is not aligned or too shallow for the “ball” of the thigh bone to connect properly. Hip dysplasia occurs in almost one-third of children with PWS. Increasing activity is the first treatment step. In contrast to typical babies with hip dysplasia who are outfitted with a harness to help the hip develop, babies with PWS should not be placed in a harness, as this will reduce their spontaneous leg motion in the crib.
Scoliosis is a side-to-side curve of the spine, which if severe, can cause major problems, including breathing difficulty and heart problems. An estimated 60-70% of PWS patients will develop a spine deformity. Of those, about 15% will need surgery to correct it. The goal is to manage a curve so that the chest develops appropriately, with enough room for the lungs to grow. Curves can begin during two important age ranges – before 4 years of age and around adolescence. The early curves probably develop because the children with PWS have ongoing issues with muscle tone, and the spine is not stabilized properly. For this reason, the advice is to not place children in an unsupported sitting position until they can pull themselves up to sit. Spine curves in the very young can be treated with bracing to decrease the size of their spinal curve. In an older child with a curve too large for a brace, surgery to implant expandable rods next to the spine might be advised to control and correct the curve. These rods can be lengthened over time, keeping up with the growth of the spine.
For more information about the Pediatric Prader-Willi Syndrome Clinic, call 314-268-4010.
