The Role of Nutrition in Spinal Muscular Atrophy

Nancy L. Kuntz, MD: Along those lines, Liz, in your team and the team you’ve pulled together in your university, what do you do to assure good nutrition and minimize aspiration?

Elizabeth Kichula, MD, PhD: Our nutritionist is probably a critical part of our team and regularly follows all our SMA [spinal muscular atrophy] patients. And I think it’s really important to have an appropriate weight and make sure we’re meeting all of our appropriate nutritional needs. And so I think nutrition is 1 important piece of that, although there are other gastrointestinal component parts that we can also talk about separately. In terms of nutrition, we do know that particularly the weaker patients don’t respond well to fasting. So they frequently do better with smaller snacks throughout the day, and I think you see this in some of the type 2s who are going to school, that they really need a little bit of that boost. And so we really work on giving them a little bit more of a protein boost that’s more long-standing than some of the sugar boost that most kids would go to right away.

We really make sure that they have an appropriate weight, and that means both avoid being underweight, which is our primary danger in some of our weaker infants, because they may develop feeding difficulties. But in our older patients, a lot of times that also means avoiding being overweight because for any patient who’s weak, carrying around a lot of extra weight can make a lot of those things more challenging as well. It’s harder to lose calories when you’re weak and exercising is more difficult. We really try to maximize all that together.

I think there are a couple of important nutritional components that have to be addressed, in particular vitamin D and calcium. Given the fact that bone health is a really important thing to think about, particularly in these patients who aren’t standing and ambulating, we make sure that we are providing at least basic needs with vitamin D and calcium I think is also a critical piece of that.

There are also a lot of other gastrointestinal complaints that I think as neurologists we often are primarily following along with the pediatrician often. And sometimes they escalate to the point where we really need our GI [gastrointestinal] colleagues as well. Constipation and reflux are very common. A lot of them also just—we see this in a lot of our patients who are weak—have their guts still moving throughout from top to bottom. Helping to make sure that they’re tolerating their feeds is a very important factor going on. I think it’s frequently helpful to really be proactive when we do get to those cases in which we need a G-tube [gastronomy tube] or an NG-tube [nasogastric tube] supplementation.

I think it’s always important to say that this doesn’t mean the children need to stop eating, but really to let them enjoy their eating—again, not to tire out with this very basic life function. They can continue to work on the skill, continue to work on it, but we need to make sure that they have maximal nutrition because for those kids who fall off the weight curve. In my experience at least, I see their motor scores also fall, and they really don’t do as well overall when their nutrition isn’t maximized.

Nancy L. Kuntz, MD: And I think you made a very good point about how the children can actually be quite obese before they actually go above the 90th or 95th percentile for weight, just because the natural state of some of the children with symptomatic SMA is that they have a decreased muscle bulk, and that puts them in the leaner categories. Now, again, we’re hoping that this might change over time with treatment and that we can forget some of these rules of thumb. But you’re right about that.

Claudia A. Chiriboga, MD, MPH: But that’s important to underscore because many pediatricians will want to fatten them up, so that they’re proportionate to their height. And that just creates fat, and what’s missing is muscle. Typically, you want to keep them on the leaner side, 5th to 10th percentile, even if they are much taller or longer.

Elizabeth Kichula, MD, PhD: And I sometimes really find it helpful just to go back and look at the patients sometimes. As much as we look at the growth charts and can follow the trends, you always have to go back and look at what the patient looks like in front of you. Particularly with a lot of our older patients who may have severe scoliosis and contractures and when height is no longer an accurate measurement to really just look at the child in front of you.

Nancy L. Kuntz, MD: I think for some of the clinical trials people have had to have chosen to look at synthesized or calculated heights from older links, and that’s probably a little bit more accurate than actual height.

Claudia A. Chiriboga, MD, MPH: I would have thought that, but I started using it, and it seems as if it overestimates height—at least the familial height for my 4 or 5 inches, I would have thought. I think there may be some excessive growth of the arms or something, because in SMA, it was striking that the parents would say there’s no way he’s going to be 6-foot-3.