LP Doc Talk
Dr. William Mackenzie, M.D. with Advanced Nurse Practitioner Colleen Ditro
Nemours Childrens’ Health System, duPont Hospital for Children
Topic: Supporting Dwarfism
January 21, 2013
www.GrowingStronger.org
Audio recording: https://youtu.be/V92Nn67aZ4Q
(opening comments)
Dr. Mackenzie: “So my daughter is 8 months old and has achondroplasia; is there any testing she should have done? My doctors don’t know much. She had an x-ray at one month and a test where they look to see if there was fluid in her head when she was two months.” So we have a child who is 8 months old with achondroplasia. Well, the recommendations that were put forward through the American Academy of Pediatrics by Judy Hall and a group a number of years ago was that all children with achondroplasia should have imaging of their foramen magnum and should be considered for sleep studies to assess for apnea that may be centrally related which is due to compression of the brain stem or peripheral which is obstructional due to a small throat area, made even smaller by large tonsils and adenoids. And also to have hearing testing because of the problems with the eustachian tubes and chronic fluid buildup and middle ear infections. So there are 8-month-old children with achondroplasia that develop normally and there are ones that are very delayed. So in our practice if we have an 8-month-old child that is developing normally, and when I say normal, they’re following the average developmental milestones for achondroplasia where the motor milestones are a little delayed compared to average stature. And by 8 months they’re sitting. They maybe doing some crawling. Some really advanced kids may be pulling up a little bit. We would not be concerned about compression at the base of the skull. But if the child is delayed, poor head control, not starting to sit independently and very floppy, we would be concerned about the possibility of compression at the base of the skull and that child would need imaging and the imaging we would do would be an MRI. Sleep studies we do very commonly, they’re easy to do. They require an overnight stay usually in the pediatric hospital and they’re very, very effective at ruling out the difference between central and obstructive apnea.
Moderator: I think the question right after that repeated the same question I believe.
Dr. Mackenzie: So I’ll make one other comment there, because it’s sort of like we just did a huge long thing on achondroplasia. The other thing that young parents with achondroplasia need to know is that in addition to the compression of the base of the skull, the children can have interference in the way that the fluid that bathe the brain is distributed. And as that builds up it can cause something called hydrocephalus. And the way of monitor for that is to monitor the growth of the circumference of the skull and we have charts that you can plot your child’s head circumference on. And it doesn’t matter that it’s big, it matters that it stays on the same percentile over time. So if your child has a big head and it’s growing within the same percentile for the achondroplasia head circumference chart, that’s fine, but if it’s jumping up that would be bad and that child would need to be evaluated for hydrocephalus.
My six-month-old child was diagnosed with Type II collagen chondrodysplasia exact type unknown. So that’s very common. The Type II collagenopathies encompass the spondyloepiphyseal, some of the spondylometaphyseal dysplasias, Kniest syndrome and Stickler. And it says, “How important is it for us to get an exact diagnosis? We’ve had a very tough time trying to find anyone in the medical profession experienced with this condition. I feel he should see a skeletal dysplasia expert. He’s doing well but he has breathing issues, cleft palate and feeding issues. When it comes to anything like feeding, physio, OT, sitting, anesthetic, no one knows that I have to refer to the internet to be taken to the UK,” and I think in Ireland it’s pronounced as Ciara. This child lives in Ireland. There are good physicians in Ireland. They tend to be in localized in larger cities in Dublin and Belfast. For a 6-month-old child with Type II collagenopathy, there’s typically more issues than the mother has mentioned. Children with Type II collagenopathies can have problems with the eyes, specifically the vitreous. The retina is not well supported in Type II collagenopathies and retinal detachment occurs commonly. These children need to be evaluated sometimes every 3 to 6 months. And it’s very important to track this because of the visual problems that can be the result of a retinal detachment. Cleft palette can have issues related to breathing, speech development and feeding, and generally requires surgical management. Any child with the Type II collagenopathy can have an unstable upper cervical spine and other spinal deformities. None of these children should be put to sleep without having at least some understanding of how stable the upper cervical spine is. And that can be sometime as simple as a plain x-ray with the neck maximally reflexed, or maximally extended, or it may involve the use of an MRI, and I’m not sure there’s one in UK. There are skeletal dysplasia centers in the world. The group in Great Britain at Great Ormond Street would be a good resource. Obviously there are a few centers in the United States that could help as well.
My daughter with achodroplasia is eleven, is it possible to enroll her in a growth study drug trial at this point? Well, the only drug trial I know about is the BioMarin BMN 111 study. At the moment, she’s too old for that trial. I believe the ages right now are 4 to 9, and the stage of the trial that it’s at at this time is evaluating the growth in achondroplasia and evaluating the safety of the drug in the pediatric population. They’ve evaluated the safety in an adult population already. So there’s no opportunity for an eleven year old to be enrolled in any drug trial at this time; probably the drug trial won’t start for at least several years. Amir, would you like to add to that?
Moderator: No, I think the age is the main factor, which you already mentioned. I think if there’s anything for parents they would be maybe interested in understanding, when could we expect the general availability. If it magically becomes available tomorrow, would the children of similar age, like 11 or 12 benefit or not at all?
Dr. Mackenzie: I think they’re still growing and they may well benefit. We don’t know yet.
Okay, next one is from Lansing, Michigan, and I know why they’re asking this question because they’re hosting the World Dwarf Games. So the first thing is, [a joke] what’s the largest operation in the United States? Lansing, Michigan. You get it? No? Okay. With the 2013 World Dwarf Games coming to the US August 3rd to 10th, what are the benefits of sports for dwarf athletes in terms of flexibility, stamina, core strengths versus the potential risk of skeletal and neurological damage. For reference, 75 to 80 percent of the participating athletes have achondroplasia as a primary diagnosis.” I would guess that’s an accurate estimate. I think that the benefits are all of those things; flexibility, stamina, core strength, the opportunity to participate in sports events against individual’s with the same diagnosis and size. The opportunity to meet athletes from all over the world and discuss issues related to your form of dysplasia in other countries. I think there are huge benefits from these dwarf games. I think the potential downsides are minor. All these kids that have unstable necks will have to have specialized x-rays. Older individuals will have to have a cardiac and pulmonary evaluation. I think there’s really very little downside here.
So the next question is from Caruthers, California, and relates to a family asking, where should their son’s spinal fusion be done? So, I don’t know that I should be advocating certain centers over another, but I’ll give you the background. So this is a 21-month-old boy with brachytelephalangic chondrodysplasia punctata with instability in the upper cervical spine. He has no signs of spinal cord compression. He has a tracheostomy. He gets his medical care at a large center in the west coast and the family is happy with this group. The surgeons have suggested that he would need fusion from the skull to the bottom of the cervical spine. And a suggestion to the family was that the surgeons are waiting until the child gets big enough and his bones are strong enough to support using a HALO. The orthopedic surgeon would like to wait until the tracheostomy has been discontinued. So I’m going to address the issues and not the place. This is a very rare form of chondrodysplasia punctata. It can be associated with cervical stenosis that is a narrow spinal canal or instability. You do the operation when the child’s spinal cord is threatened or already compromised. You do not wait until the child gets bigger because during that time there may be irreversible spinal cord problems. There are sometimes challenges for the surgeon but we do not wait until they get older or they get stronger. We do it when it needs to be done and we have to adapt. We do not have to wait until the tracheostomy is removed unless there is need for an anterior approach but even so you can still do that with a reasonable incidence of infection. So when you choose for a hospital, you have to choose a facility where a surgeon is comfortable and experienced at doing these procedures. And that anesthesia is comfortable giving an anesthetic and maintaining the airway and that the post-operative physicians, that’s usually the intensive care physians, are comfortable dealing with the issues that occur in these children. That child was 21 months.
The next question is, “What are your thoughts on using excersaucers, i.e. exercise saucers. My daughter will be one-years-old next month and I see some people use them with their children. That daughter has achondroplasia. How do I know if the kyphosis is bad? I read that 10 percent will require surgery or back brace. None of my doctors know what I should watch for.” Well, generally excersaucers with wheels should not be use. I don’t think they’re very safe. If you have a wheeled excersaucer and you happened to leave the door to the basement open that could be a fatal injury. I don’t mind excersaucers that are stable on the ground. Any sort of system where the child is supported, it’s not a problem when used in moderation. If you use an excersaucer to park your child with achondroplasia for 3 hours, that’s not a good idea. If you use an excresaucer for half an hour of play time, that’s perfectly fine. Most children with achondroplasia have a kyphosis. They should not be propped into a sitting position for hours at a time, but short periods is okay. A small percentage of kids with kyphosis do not improve spontaneously when they start walking or when they get strength through their trunk.
The next question is from Pakistan, “This is an individual with achondroplasia who said he’s a student and ocassionally has tiredness in his hand when he’s writing for long periods. Achondroplasia, not only has problems with narrowing at the base of the skull, but also narrowing of the spinal canal all the way from the top to the bottom of the spine. I’ve had to treat teenagers with compression of the spinal cord in the part in the neck or in the cervical spine. That can get so bad that you need to do decompression surgery for this narrow canal, but usually not in someone who is in their teenage or young adult years. You have to make sure that the discomfort is not due to elbow problems or forearm problems. And that the many people with achondroplasia have very, very short fingers and it can be tough to hold pens or pencils making it more difficult to write. You can use modifications to pens such as big grips to make that better. So first of all, you have to decide what the problem is and then decide how to manage it.
The next question is about limb lengthening for height in pseudoachondroplasia. “Not all doctors who perform limb lengthening will do so on those with pseudoachondroplasia. What are your thoughts on why it is more risky with pseudos and do you have any experience with this?” So, there is extensive experience throughout the world of doing extended limb lengthening in achondroplasia. Achondroplasia is due to an FGFR3 mutation, which interferes with the longitudinal growth of bones through cartilage. The joints are not a effected primarily. So the surface of the joints, the articular cartilage in the joints, is normal in achondroplasia. In psedudoachondroplasia, it’s caused by a cartilage oligomeric matrix protein abnormality. This results in abnormal cartilage in the joints. So while people with pseudoachondroplasia wear out their joints and need joint replacements in adult, this is very rarely required in achondroplasia. So when you do extended limb lengthening you put extensive pressure across the joints. And I’m concerned about degenerative changes that may occur in the joints of people with pseudoachondroplasia who have had extended limb lengthening. I have used external fixators to straighten out the legs of children with pseudoachondroplasia, but I have not done extensive lengthening because of the concerns that I have and just voiced.
I’m going to jump the next question because it doesn’t make sense. It talks about sitting but doesn’t give the diagnosis.
The next question is an individual with achondroplasia who is 40 years old. This individual has extreme back pain on a daily basis. And an MRI in numbered years ago showed spinal stenosis in the lower part of the back. The family doctor has this person on pain-killers, but that isn’t working. This individual has significant pain throughout much of her body. This individual wore a back brace and leg braces for many years to control leg and back deformity. So this person could have several problems. So she is 40 years old and has back pain and MRI findings of spinal stenosis. Spinal stenosis is present in every single person with achondroplasia, so having an MRI that shows spinal stenosis is not surprising, but it can give you a sense of the severity. Spinal stenosis can cause leg pain and back pain, but it will cause both. And the main thing it does to the legs is something called neurogenic claudication, which means as you walk you get pain, weakness, numbness or abnormal sensation in your legs that improves when you stop and take a rest. There is no mention of that in this question. When someone has severe back pain with no leg pain or neurogenic claudication, then it’s unlikely that spine surgery will help unless there is another problem like a disc abnormality, when you have a failed disc in the lumbar or thoracic spine. So this patient requires a very extensive evaluation to make sure exactly where the pain is coming from and then make a decision about how to manage it. One of the problems when the pain is being treated with narcotic for many years is that people can become very dependent on the narcotics and develop psychological syndromes due to chronic pain. And that can sometimes be very difficult to differentiate from the organic problems that are present that cause back pain. Colleen, any comments about that?