Pseudoachondroplasia

“Pseudo” means “false.” Thereby, this disorder is one that resembles, but is clinically distinct from, achondroplasia.The incidence of pseudoachondroplasia is estimated at 1 in 30,000, however the birth prevalence is not yet known (2).

 
How Pseudoachondroplasia Is Inherited

Pseudoachondroplasia can either be inherited in an autosomal dominant inheritance pattern (1). Parental germinal mosaicism is often found, which explains why many affected children have unaffected parents. Mosaicism causes the condition to behave in an autosomal recessive fashion.

 
Causes of Pseudoachondroplasia

Pseudoachondroplasia results from a mutation in the gene coding for cartilage oligomeric matrix protein (COMP) (1). COMP is a normal constituent of the extra-cellular matrix in cartilage, ligaments, and tendons. Defective COMP results in the accumulation of proteoglycans within cartilage cells.

 
Physical Characteristics

Both the epiphyses and metaphyses are affected in pseudoachondroplasia. Clinically, it is recognized as a form of short-limbed dwarfism, with body proportions similar to those of achondroplasia, yet with normal-sized heads and facial features.

The postnatal onset of short-limbed growth deficiency will not become apparent until between 18 and 24 months of age. Pseudoachondroplasia manifests itself over time. Ultimately, adult stature is between
82 and 130 cm.

Face & Skull
  • Normal head size and facial features
Trunk, Chest, & Spine:
Arms & Legs:
What are the X-ray characteristics?

The radiographic features of pseudoachondroplastic patients include short and broad long bones with flaring of the metaphyses. Epiphyseal ossification is delayed. The epiphyses appear irregular and fragmented. The hips and knees are primarily affected. Due to their dysplastic nature, the carpals ossify late.

In the pelvis, the acetabulum (hip socket) is shallow and accentuates hip dysplasia. The triradiate cartilage is also late to mature and ossify. Arthrograms are helpful in identifying joint surfaces and planning surgery for angular deformities. The capital femoral epiphyses are small and irregular in children; in adults, there is marked dysplasia of the femoral head. The femoral head is flattened and fragmented. This leads to hip joint incongruity and exacerbates the effects of hip subluxation.

X-rays of the spine show platyspondyly and flame-shaped anterior projections. The interpedicular distance does not progressively decrease in the lumbar spine. In the neck, lateral X-rays of the cervical spine may reveal odontoid hypoplasia. The vertebrae will at first seem deformed, but the irregularities generally disappear by adolescence. Flexion-extension radiographs should be obtained to rule out atlantoaxial instability. MRI scans of the cervical spine (static, flexion/extension views and CSF flow studies) are helpful in identifying any compression of the spinal cord.

 
Making the Diagnosis

The average length at birth is 49 cm, which is within the normal range. Pseudoachondroplasia is therefore not readily recognized at birth. But, lack of longitudinal growth manifests itself in the first 2 years of life (below 5th percentile on standard growth charts). By this point the abnormal gait is present and measurements suggest pseudoachondroplasia. Diagnosis is typically made between 1 and 4 years of age and is based on clinical examination and characteristic X-ray appearances. Prenatal testing is now available by direct DNA analysis. The test detects the abnormal COMP gene by mutation scanning. Prenatal diagnosis may be appropriate during pregnancy in women with pseudoachondroplasia. It must be stressed that the majority of cases are spontaneous mutations.

 
Musculoskeletal Problems
Spine

The cervical spine should be monitored for the presence of atlantoaxial instability. Lateral flexion-extension x-rays of the cervical spine is recommended, if a pre-existing abnormality such as hypoplastic odontoid is present. Posterior cervical decompression and fusion should be performed if the instability exceeds 8 mm or neurological symptoms (cervical myelopathy) occur. Scoliosis should be looked for and is managed similar to idiopathic curves. Lateral c-spine x-rays should be routinely obtained in all children with pseudoachondroplasia undergoing surgery for any reason.

Lower Limbs

Angular deformities around the knee are corrected using osteotomies. Careful pre-operative planning is essential to restore normal mechanical axes in sagittal and coronal planes (down the middle of the body). Since the epiphyses are distorted, intraoperative arthrography may be necessary to properly visualize the joint surfaces. The effect of ligamentous laxity on alignment should be ascertained as part of the pre-operative planning. Recurrence of deformity is common and several procedures may be necessary to achieve lower extremity skeletal alignment at maturity. Up to 50% of adults will require joint replacement surgery for early onset degenerative arthritis. Hip/ knee replacement surgery in patients with skeletal dysplasia is a technically demanding exercise due to abnormal skeletal size and shape. Subluxation of the hips is a combination of femoral deformity, failure of epiphyseal ossification, acetabular dysplasia (failure of hip socket development), and joint contractures (flexion and adduction). A combination of femoral and pelvic osteotomies may be necessary. Since the femoral head is flattened, a valgus proximal femoral osteotomy is preferred to a varus procedure. If the hip joint is not congruous, acetabular augmentation procedures (Chiari osteotomy or Shelf procedure) are used to salvage the hip.

 
Problems Elsewhere in Body

Few problems, if any, occur and good general health can be expected.

 
What to Watch For

Pseudoachondroplastic patients should look out for neurological symptoms such as weakness of the lower limbs, incontinence, pain in the legs, reduced endurance, and tingling/ numbness of the legs. These symptoms may indicate compression of the spinal cord in the neck.

Lower extremity pain of gradual onset or changes in walking (waddling/ limping) may also result from altered alignment of the legs. In later life, pain in the hips and knees is usually the result of degenerative arthritis.

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.

 
References
  1. Jones, Kenneth L. Recognizable Patterns of Human Malformation. Philadelphia, PA: Elsevier Saunders. 2006.
  2. Posey, Karen L. Hayes, Elizabeth. Haynes, Richard. Hecht, Jacqueline T. 2004. Role of TSP-5/COMP in Pseudoachondroplasia. The International Journal of Biochemistry and Cell Biology. 36: 1005-1012.
  3. Scott, Charles I. Dwarfism. Clinical Symposium, 1988; 40(1);11-14.
  4. Spranger, Jurgen W. Brill, Paula W. Poznanski, Andrew. Bone Dysplasias: An Atlas of Genetic Disorder of Skeletal Development. Oxford: Oxford University Press. 2002.

Trusted Insights from Nemours' KidsHealth

Relaxation Techniques for Children With Serious Illness

Managing Stress

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.

Focused Breathing

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.

Guided Imagery

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.

Music Therapy

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

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.

Massage Therapy

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.

Learn More

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