Physical Therapist's Guide to
Prader-Willi syndrome is a complicated genetic condition that affects many body systems, and usually results in mild to moderate intellectual disability. Infants born with Prader-Willi syndrome typically have low muscle tone, growth problems, difficulties feeding/sucking, and experience developmental delay. Between the ages of 1 and 4 years, children with the syndrome develop an insatiable appetite, causing rapid weight gain, which may lead to obesity. Scoliosis and other bone problems may develop as well as behavioral difficulties. In the United States, between 1 in 15,000 and 1 in 25,000 live births are affected by Prader-Willi syndrome, and the disease affects between 350,000 and 400,000 people worldwide. Physical therapists partner with children born with Prader-Willi syndrome and their families to help them achieve their maximum potential, and to lead fulfilling lives.
What is Prader-Willi Syndrome?
First described in 1956, Prader-Willi syndrome is a genetic disorder caused by defective or missing genes. In about 70% of cases, genes inherited from the father are deleted on a specific section of chromosome 15, as a baby develops in the womb. In another 25% of cases, 2 copies of chromosome 15 are inherited from the mother, and replace the genes normally inherited from the father. When only the genes from the mother are present, neither of the genes are active. Prader-Willi Syndrome occurs randomly and affects males and females equally. The severity of symptoms varies from person to person.
Until recently, most individuals with Prader-Willi syndrome died in their 40s due to complications resulting from morbid obesity. However, with diligent weight control and support, persons with Prader-Willi syndrome can remain healthy and live a normal life span.
Signs and Symptoms
Prader-Willi syndrome has a wide range of physical, mental, and behavioral symptoms, and the severity of symptoms varies from person to person. People with Prader-Willi syndrome have distinctive facial and body features, including almond-shaped eyes, short stature with small hands and feet, and a down-turned mouth. Low pigmentation in the skin is common; people affected tend to have lighter hair color and fairer skin than their family members.
Prader-Willi syndrome is classified in 2 stages:
First Stage: Birth to Approximately 2 Years of Age
The first stage of the syndrome is marked by factors, including low muscle tone (hypotonia), feeding problems related to a poor ability to suck and use the muscles of the mouth, and developmental delays. Despite difficulties gaining weight early on, infants with the syndrome have been shown to already have high body fat compared to lean body mass (muscle) than other infants, so they need to take in fewer calories to meet their energy needs. Most infants with Prader-Willi syndrome need help feeding during the first 4 to 6 months of life. Feeding assistance may include nursing systems and feeding tubes.
Second Stage: Starting Between 1 and 4 Years of Age and Continuing Into Adulthood
The second stage is marked by the development of an insatiable hunger (called hyperphagia) and rapid weight gain. Individuals never feel full and often develop food-seeking behaviors. Dysfunction in an area of the brain is believed to be responsible for the hyperphagia. Obesity often begins at this point, and weight gain is complicated because persons with Prader-Willi syndrome need only 60% to 80% of the calories that a typical individual needs, due to their high body-fat composition and corresponding lower lean body mass (muscle).
Other symptoms that may be present during stage 2 include:
- Hypotonia (low muscle tone)
- Hip dysplasia (hip problems)
- Decreased bone density
- Small stature (due to growth hormone deficiency), with small hands and feet
- Problems breathing when sleeping (such as sleep apnea)
- Absent or incomplete puberty
- Behavior and learning challenges
- Scoliosis(curvature of the spine)
- Vision problems
- Insensitivity to pain, which can mask other symptoms
How Is It Diagnosed?
A diagnosis of Prader-Willi syndrome is based on clinical symptoms; it should be considered in any infant born with severely low muscle tone. A blood test is used to confirm the diagnosis, and can accurately identify more than 99% of persons with Prader-Willi syndrome. The blood test will be ordered by the physician.
How Can a Physical Therapist Help?
Your physical therapist will serve as a valuable partner to help your child reach maximum potential. First, your physical therapist will perform an evaluation, including:
- Birth and Developmental History. Your physical therapist will ask about your child’s birth, hospital treatment, and motor development (such as, head control, rolling, sitting unsupported, crawling, and walking).
- Medical History/Health Concerns. Your physical therapist will ask about any medical problems or concerns, hospitalizations, recent doctor appointments, and any specialists involved in your child's treatment. You may be asked to report your child's feeding habits and growth.
- Parental Concerns. Your physical therapist will ask about your concerns and goals for your child. We are here to help!
- Physical Exam. Your physical therapist will perform a physical exam to determine your child’s strengths and weaknesses. It may include measuring height and weight, observing movement patterns, and assessing muscle strength and tone. Your physical therapist will use specific tests to determine your child’s current level of muscle function, balance, and coordination.
Your physical therapist may identify the need for other health professionals to be consulted, such as an orthotist, who can recommend a brace to help with walking. A physical therapist helps children and adults with Prader-Willi syndrome increase their movement ability and muscle strength, so they can function at their best potential throughout their lives. Physical therapy may be provided in the home, at school, or in an outpatient setting.
Your physical therapist will provide services through the different stages of your child's life, and work with other service providers, such as occupational therapists and speech language pathologists, to coordinate care and ensure that all your child's needs and goals are being addressed in the safest and most effective way possible.
Physical Therapy in the Early Years: Birth to Age 4
Physical therapists work with parents to educate them about their infant's condition, and provide training in activities they can perform with their baby to promote movement and muscle strength. Your physical therapist may also suggest changes to make in your home to encourage play skills, and increase opportunities for your baby's movement. Children at this age learn through play. Your physical therapist will develop an individual plan of fun, play-focused treatment based on your child’s strengths and weaknesses, and on your goals.
Physical Therapy in the School Years: Ages 5 to 17
Physical therapists work in schools and outpatient clinics to help children with Prader-Willi syndrome function as independently as possible, as they get older and attend school. Your physical therapist may provide training to you and to caregivers at home and in school to ensure the highest quality of life for your child. As a child ages, the child with Prader-Willi syndrome often struggles with obesity and inactivity. Your physical therapist may suggest a fitness program or specific activities designed to increase aerobic fitness, and promote increased mobility and activity. Some children may receive growth hormone (rhGH) treatment; research suggests that rhGH treatment combined with physical training results in the greatest benefits. Scoliosis is also common in children with Prader-Willi syndrome; it is diagnosed in 30% to 80% of persons with the syndrome, depending on their age. Your physical therapist will check for signs of scoliosis.
Physical Therapy Into Adulthood: Ages 18+
For adults living with Prader-Willi syndrome, inactivity and obesity-related health issues can result in decreased mobility and independence. Osteoarthritis (decreased bone-mineral density) is also common, and can result in limited joint movement, causing pain. Your physical therapist may suggest adaptive equipment and home modifications to help with mobility and independence in the home. Your physical therapist can also design a fitness program to improve aerobic fitness, and increase muscle mass and bone density.
Can this Injury or Condition be Prevented?
Prader-Willi syndrome is a genetic change that is usually random, happening at the time the baby is forming in the mother's womb. Therefore, the syndrome is very difficult to prevent, but all pregnant women should seek excellent prenatal care and follow the suggestions of health care practitioners. Genetic testing during pregnancy is possible and might be helpful, if the specific genetic change is known.
Although Prader-Willi syndrome affects many aspects of health, improvements in health care have resulted in many individuals with the syndrome now living into their 70s. Physical therapists and other health care providers can help diminish some of the effects of the syndrome, including the development of obesity. Strong nutritional management and the use of recombinant human growth hormone treatment (rhGH) have shown to produce significant positive effects, including increased, appropriate growth; increased muscle strength; improved bone health; and improved motor (movement) development (in infants). The use of rhGH growth hormone treatment may be recommended as early as 4 to 6 months of age, or at older ages. Children need to be monitored by physicians regarding hormone treatment.
Real Life Experiences
Ethan is a 17-month-old boy with Prader-Willi syndrome. Ethan was born full-term and was diagnosed with the syndrome as a newborn. His parents adore him, and have sought the best medical care for him.
Ethan was diagnosed with hip problems when he was 5 days old; he was placed in a Pavlik harness to gently encourage proper hip development, which he wore until he was 7 months old. Ethan struggled with feeding, and needed a feeding tube while he was in the neonatal intensive care unit (NICU).
Ethan also received gentle physical therapy while in the NICU to increase his muscle tone and movements. A speech-language professional also worked with Ethan to improve his mouth movements and feeding skills.
Once discharged home, Ethan was referred to early intervention services, from which he continues to benefit. Ethan is seen at home and at his day care facility by a team of health professionals, including a special educator, an occupational therapist, and his physical therapist.
Ethan has begun rhGH growth hormone treatment, and his weight and growth are watched carefully. Ethan is now taking solids and liquids by mouth, but he does continue to receive supplemental nutrition through his G-tube.
Ethan continues to have low muscle tone but is very curious and motivated to move. His physical therapist has helped him learn to sit unsupported, and use rolling to move around and explore his environment. Ethan is now able to support himself briefly on his hands and knees, and put weight on his feet to stand with some support. His physical therapist uses games and toys to gain Ethan’s interest and encourage him to develop more movement skills, and to improve his strength.
Each of Ethan’s therapy providers shares activities and games with Ethan’s parents that can be done at home, so he can build his thinking and movement skills.
As Ethan continues to grow and develop, his physical therapist will work with him and his parents to advance his motor skills into crawling, walking, climbing stairs, and running. To help him walk at his highest level, Ethan may wear lower leg braces, and have inserts in his shoes.
As Ethan grows and matures, his team of health care professionals, including his physical therapist, will offer support and guidance to help ensure that he lives a full and productive life.
What Kind of Physical Therapist Do I Need?
Every physical therapist is trained by education and practical experience to treat a wide variety of conditions and injuries. Some things to consider as you choose a physical therapist include:
- A physical therapist who focuses on treating infants and children.
- A physical therapist with experience in pediatrics who is committed to working with other health care professionals to provide the best possible treatments for individuals with Prader-Willi syndrome.
- A physical therapist who is a board-certified clinical specialist or who has completed a residency or fellowship in pediatrics. This therapist will have clinical expertise, knowledge, and experience that may apply to developmental conditions, such as Prader-Willi syndrome.
You can find physical therapists who have these and other credentials by using Find a PT, the online tool built by the American Physical Therapy Association to help you search for physical therapists with specific clinical expertise in your geographic area.
General tips when you are searching for a physical therapist (or any health care provider):
- Ask family, friends, or other health care providers for recommendations.
- When you contact a physical therapy clinic or agency, ask about the physical therapists’ experience in treating children with Prader-Willi syndrome, or other developmental or genetic conditions.
- During your first visit with the physical therapist, be prepared to describe your child’s symptoms and motor skills in as much detail as possible.
The American Physical Therapy Association (APTA) believes that everyone should have ready access to information that can enable them to make health care choices, and also prepare them for a visit with their health care provider.
The following articles provide some of the best scientific evidence related to physical therapy treatment of Prader-Willi syndrome. The articles report recent research and give an overview of the standards of practice both in the United States and internationally. The article titles are linked either to a PubMed* abstract of the article or to free access of the full article, so that you can read it or print out a copy to bring with you to your health care provider.
Rubin DA, Wilson KS, Wiersma LD, Weiss JW, Rose DJ. Rationale and design of active play @ home: a parent-led physical activity program for children with and without disability. BMC Pediatr. 2014;14:41. Free Article.
Reus L, Pelzer BJ, Otten BJ, et al. Growth hormone combined with child-specific motor training improves motor development in infants with Prader-Willi syndrome: a randomized controlled trial. Res Dev Disabil. 2013;34(10):3092-103. Article Summary on PubMed.
Bakker NE, Kuppens RJ, Siemensma EP, et al. Eight years of growth hormone treatment in children with Prader-Willi syndrome: maintaining the positive effects. J Clin Endocrinol Metab. 2013;98(10):4013-4022. Free Article.
Mccandless SE; Committee on Geriatrics. Clinical report—health supervision for children with Prader-Willi syndrome. Pediatrics. 2011;127(1):195-204. Free Article.
Jin DK. Systematic review of the clinical and genetic aspects of Prader-Willi syndrome. Korean J Pediatr. 2011;54(2):55-63. Free Article.
Reus L, Zwarts M, Van vlimmeren LA, Willemsen MA, Otten BJ, Nijhuis-van der sanden MW. Motor problems in Prader-Willi syndrome: a systematic review on body composition and neuromuscular functioning. Neurosci Biobehav Rev. 2011;35(3):956-969. Free Article.
Cimolin V, Galli M, Grugni G, et al. Gait patterns in Prader-Willi and Down syndrome patients. J Neuroeng Rehabil. 2010;7:28. Free Article.
Vismara L, Cimolin V, Grugni G, et al. Effectiveness of a 6-month home-based training program in Prader-Willi patients. Res Dev Disabil. 2010;31(6):1373-1379. Article Summary on PubMed.
Lewis CL. Prader-Willi syndrome: a review for pediatric physical therapists. Pediatr Phys Ther. 2000;12:87-95. Article Summary not available.
Genetics Home Reference. Prader-Willi syndrome. Published March 10, 2015. Accessed March 16, 2015.
Foundation for Prader-Willi Research. Diagnosis and treatment. Accessed March 16, 2015.
* PubMed is a free online resource developed by the National Center for Biotechnology Information (NCBI). PubMed contains millions of citations to biomedical literature, including citations in the National Library of Medicine’s MEDLINE database.
Authored by Michelle Caldwell, PT. Reviewed by the editorial board.