“Hypo” is a prefix meaning “below” or “less.” It follows that this dysplasia is considered a more mild or atypical form of achondroplasia. The incidence of hypochondroplasia is approximately 180,000 to 312,000 live births (2).
Hypochondroplasia is genetically heterogeneous. Approximately one-half of hypochondroplastic patients have a mutation within the fibroblast growth factor receptor 3 (FGFR3) gene (2).
Due to its mild nature, it is often times difficult to differentiate between “familial” shortness of stature and hypochondroplasia. Hypochondroplasia seems to be the grey area between achondroplasia and being constitutionally shorter than average. The average adult height of hypochondroplastic patient varies between 52 and 58 inches.
The major radiographic features of hypochondroplasia include narrowing of interpediculate distances with anterioposterior shortening of pedicles. Vertebral bodies in lumbar region of spine have increased dorsal concavity. The height of the vertebral bodies is normal. The deformities of the spine, however, are not as pronounced as in the case of achondroplasia.
The pelvis is square with short ilia, although the flare of the iliac crests is normal. The sacrum is hypoplastic and low set on the iliac bones, effectively narrowing the transverse diameter of the pelvis. The tubular bones are short and with mild metaphyseal flare (most evident at the knees). The styloid processes of the ulnae are frequently long. Femoral necks are short and broad.
Distal fibulae are long in comparison to tibia. In children, growth plates of distal femurs exhibit a shallow, V-shaped indentation. This is due to slower enchondral bone growth at the center of the growth plate as compared to growth at the periphery. Again, this change is more mild in hypochondroplasia than in achondroplasia. Generalized brachydactyly is mild to moderate. Occasionally, the neurocranium is slightly larger.
Considering that the skeletal deformities of hypochondroplasia are moderately similar to those of achondroplasia, radiographic findings must be well-scrutinized to give a correct diagnosis. The best features to examine are the skull and pelvis; each are more severely affected in the case of achondroplasia.
In order to differentiate between hypochondroplasia and familial short stature, vertebral and pelvic changes should be considered. Vertebral abnormalities are characteristic only of hypochondroplasia. The appearance of the long bones may be similar to metaphyseal chondrodysplasia, Schmid type. Again, the differential feature is the vertebral abnormalities, which are only present in hypochondroplastic patients. It is difficult to diagnosis hypochondroplasia in infancy, although birth length may be slightly below average. By 3 years of age, slow growth and bowlegs are early indicators of this skeletal dysplasia.
Genu varum and outward bowing become pronounced as children age and weight bearing increases. Surgical straightening may be necessary.
Inversion of the Feet
Inversion of the feet may result becuase of the relatively longer fibulae.
Considerable discomfort in the knees, ankles, or elbows may occur, especially during childhood. Into adulthood, the pain is most prominent in the lower back.
Spinal stenosis may result in cord compression. Symptoms include activity-related leg pain that is relieved on squatting down, tingling, pins and needles, numbness in the feet (paraesthesias), weakness of the legs, or disturbances in control of bladder or bowel function (incontinence). X-rays, CT and MRI scans of the lower spine, confirm the diagnosis. Obesity greatly increases the risk of this problem developing.
Approximately 10% of hypochondroplastic persons have learning problems.
Compressive myelopathy and radiculopathy occur, albeit less frequent
Woman who become pregnant often times require a cesarean section, albeit vaginal delivery is still possible.
Considering that the course and complications of hypochondroplasia are slightly different from achondroplasia, it is important for a radiologist to correctly diagnosis this specific skeletal dysplasia early on.
For children and adults of any size or stature, obesity should be avoided. However, in the case of hypochondroplasia, patients must put forth greater effort to stay active and physically fit. Increased weight bearing of the joints can lead to extreme discomfort and possible neurological complications. Diminishing motor milestones, decreased endurance, apnea or any neurological symptoms should be quickly evaluated by an experienced physician.
Generally all skeletal dysplasias warrant multidisciplinary attention. Regular assessment by an orthopedist, geneticist, pediatrician, dentist, neurologist, and physical therapist will provide the most comprehensive treatment.
- Desch, Larry W. Horton, Willaim A. An Autosomal Recessive Bone Dysplasia Syndrome Resembling Hypochondroplasia. Pediatrics. 75, No 4: 786-789. 1985.
- Jones, Kenneth L. Recognizable Patterns of Human Malformation. Philadelphia, PA: Elsevier Saunders. 2006
- Newman, Donald E. Dunbar, Scott. Hypochondroplasia. Journal of the Canadian Association of Radiologists. 26: 95-103. 1975.
- Scott, Charles I. Dwarfism. Clinical Symposium, 1988; 40(1):9-10.
- Spranger, Jurgen W. Brill, Paula W. Poznanski, Andrew. Bone Dysplasias: An Atlas of Genetic Disorder of Skeletal Development. Oxford: Oxford University Press. 2002.
- Walker, Bryan A. Murdoch, Lamont J. McKusick, Victor A. Langer, Leonard O. Beals, Rodney K. Hypochondroplasia. American Journal of Disease of Children. 122: 95-104. 1971.
From Nemours' KidsHealth
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Relaxation Techniques for Children With Serious Illness
Nothing about serious illness is easy, but one of the hardest things for parents may be watching their child struggle with pain, stress, and anxiety.
Despite what we may sometimes tell ourselves, stress is not just "in our heads." The stress response — also called the flight-or-fight response — causes a rush of adrenaline and other hormones that trigger physical changes in the body: your heart races, your blood pressure rises, you breathe faster, your digestion slows, and your pupils dilate. Chronic stress takes a toll on the body as well as the mind.
The good news is that using a variety of mind-body relaxation techniques can help short-circuit the flight-or-fight response. Relaxation techniques not only can lessen a child's physical symptoms, they can also help him or her (and you!) regain a sense of control and confidence over a situation, helping everyone find moments of peace amid the chaos and isolation of illness and medical treatment.
Techniques That Can Help
These techniques are designed for parents and kids to practice together. Most can be done in a few minutes wherever you are, whether that's a quiet place or a crowded hospital, without any special tools.
However, it's important to note that these techniques should be used as a complement to conventional medical treatment for anxiety and pain, and not as a replacement — doing so could do a child more harm than good.
If your child is suffering from anxiety or pain, ask your doctor what can be done to help. And always check with your health care team to make sure that your child's symptoms are related to stress and not a different medical problem.
Pain and stress can leave a child breathing faster and shallower, or even holding his or her breath — all of which can actually keep the stress response going and heighten the intensity of pain. Paying attention to breathing can help calm the mind.
Try this exercise with your child:
- Step 1. Sit or lie comfortably and put one hand on your stomach, the other on your chest.
- Step 2. Close your eyes and try to relax all of your muscles, one by one, from the tips of your toes to the top of your head. Don't forget to relax the muscles in your face, neck, and jaw; you may be storing a lot of tension there.
- Step 3. Breathe deeply and regularly for several minutes— and try to make your stomach (abdomen) rise and fall, not only your chest. This will help you deepen your breath.
- Step 4. Pay attention to each breath; try to turn all your thoughts to each inhale … exhale. As you breathe out, imagine the tension leaving your body with the breath.
At first, it may be difficult for you and your child to focus on breathing. Distracting thoughts are normal — but rather than following a thought and letting it consume you, try to let it drift out of your mind, like a balloon.
Relaxation Response Method
This technique asks a person to focus on breathing and quiet the mind to create a sense of calmness and well-being. And by repeating a word, phrase, or prayer during the exercise, the mind is able to stay focused more easily. When practicing this, it's normal for thoughts to pop into the mind. Tell your child to disregard them and just focus on the word or phrase he or she is repeating.
Resembling an Eastern form of meditation, this technique — called the relaxation response — was popularized and put into Western practice in the 1970s by Herbert Benson, MD. To elicit the relaxation response, follow Steps 1-4 above, and then:
- Step 5. Pick a focus word, phrase, sound, or prayer such as "om," "one," or "peace."
- Step 6. As you breathe, say the focus word silently to yourself as you exhale.
- Step 7. Continue for 5 or 10 minutes, ideally building up to 10 to 20 minutes for each session.
- Step 8. When you're finished, do not stand up immediately. Continue sitting quietly for a bit, letting other thoughts back into your mind. Open your eyes, but stay sitting for another minute before getting up.
When practicing, go at your own pace. Don't feel like you have to achieve a deep level of relaxation right away. Often, feelings of calmness and well-being are felt later on or at times of crisis.
To achieve ongoing results, try to practice the technique with your child once or twice daily, but not within 2 hours after eating, as digestion can interfere with the relaxation response. Some people find that the best time to meditate is first thing in the morning, before breakfast.
A growing body of medical research suggests that imagery also can help lessen pain and anxiety, and promote positive feelings. In fact, studies have found that people who practice guided imagery during chemotherapy feel more relaxed and positive about their chemo experience than those who don't use the technique.
Guided imagery (also called "visualization") often works best when a person starts with a few minutes of focused breathing. Here's how it works: With eyes closed, imagine a safe place or a location you once visited that brought a feeling of contentment and joy. Hold on to the image of that place for a while, trying to picture all the sights and sounds:
- What does the ground beneath you feel like? Is it weather warm or a chilly? Is there a breeze?
- Are there any animal noises in the distance, or nature sounds (like running water) that you could hear?
Getting as descriptive as possible about this safe place will help you and your child get "into" the moment and feel relaxed.
Some children find this exercise more helpful when they are "guided" by a parent, another live instructor, or with a guided imagery CD or DVD.
As with meditation, distracting thoughts will float into the mind as you practice guided imagery. Acknowledge these thoughts, and then let them drift away while you move your attention back to the images in your mind and sounds you hear.
Just as pleasant images can calm the mind and soothe the body, so can music. Kids who undergo music therapy — the research-based use of music to lift moods and promote mental and physical well-being — have been found to have lowered heart rates and blood pressure, and improved anxiety.
Many hospitals provide a licensed, trained music therapist who can work individually with kids to develop a customized treatment plan that engages them in:
- active play that includes listening to music
- dancing or moving the body to music
- playing instruments or improvising on them
- singing along
To participate in music therapy, your child doesn't need to read music or have any special musical talents. And the best part is that you can practice music therapy at home. By choosing music that both you and your child enjoy — and setting aside time to listen, dance, sing, or experiment with an instrument together — you, too, can teach your child the joys of music.
Energy therapy is based on the theory of bioelectromagnetics, the belief that the electrical currents in all living organisms produce magnetic energy fields that extend beyond the body. Proponents of this therapy believe that gentle, light touch or above-the-body hand movements can redirect energy to places where it's needed in an effort to bring energy into "balance" or harmony.
While the principles of energy therapy have not been scientifically proven, practitioners say it promotes healing and helps kids feel more relaxed, less anxious, and less bothered by pain.
Many different types of energy therapy are practiced all over the world, including therapeutic touch, healing touch, Reiki and Johrei (from Japan), and Qi gong (from China).
In the United States, some hospitals offer therapeutic or healing touch as a complement to standard treatments for anxiety, pain, or other medical problems.
And some nurses, doctors, or other health care providers are certified in healing touch techniques. They may be able to offer this service to your child, or teach you how to practice healing touch at home.
If you like to take a more hands-on approach to soothing and comforting your child, you might prefer massage. The benefits of massage are well known, offering muscle relaxation and increased blood flow and oxygen to body parts to help alleviate stress and ease pain.
But some types of massage are not recommended for certain types of conditions, so check with your doctor first before massaging your child or taking your child to a massage therapist.
The most common forms of massage used in complementary medicine include:
- Swedish massage. Therapists use their hands to move muscles and joints with long, gliding strokes, tapping movements, friction (made by moving hands quickly) and kneading. Massage oils may be used, so be sure to tell the therapist about any allergies or sensitivities to ingredients that your child may have.
- Deep-tissue massage. Many of the same techniques are used as in Swedish massage, only therapists apply more pressure to specific areas, concentrating on the deeper layers of muscles and connective tissue.
- Trigger-point massage. Like deep-tissue massage, this technique massages deeper layers of tissue, focusing on what therapists call trigger points ("knots") within the connective tissue or muscles that are usually painful when pressed.
Many hospitals have massage therapists on hand to offer massages to both patients and their family members, so find out if massage therapy is offered at your hospital.
These are just a few of the many methods designed to help patients and families cope with pain and anxiety. Many people find that yoga, stretching, or light, gentle exercise also helps to quiet the mind and sooth the body.
To learn more about relaxation techniques, talk to your child's health care team.
Reviewed by: Larissa Hirsch, MD, and Walle Adams-Gerdts, RN, BA, HTCP/I
Date reviewed: April 2011