Sleep and PWS
Prior to starting recombinant growth hormone (rGH), our son underwent a sleep study to examine his incidence of sleep apnea. Because of the recent case studies of morbidity due to sleep apnea associated with rGH therapy, this is now becoming a prerequisite prior to beginning rGH treatment.
Our son had no issues identified in the first sleep study and had healthy sleep patterns with some mild obstructive sleep apnea.
After 3 months of rGH therapy, our endocrinologist asked us to follow up with a second sleep study to examine whether rGH had negatively impacted our son’s sleep.
Unfortunately, the second study showed that he had an increase in the apnea index, implying that compared to the first study, he had a higher number of obstructive sleep apnea events. Because of the Thanksgiving holidays, our endocrinologist had not yet looked at the study, but based on this study, our endocrinologist’s nurse called and asked us to terminate rGH. We refused.
As it turns out, we had a long and interesting conversation with the sleep clinic director, who had performed the sleep study, and he explained the details of a sleep study and its implications better.
I believe that this is important information for any PWS parent or person with PWS to be aware of and hence I am posting it here. Again, this is based upon our experience and what I gathered from our conversation with the sleep expert.
First, he explained to us that numbers such as the apnea index and the number of hypopneas (shallow breathing) per hour in an infant/toddler do not mean much. These numbers are based on adult figures because no data is available on infants/toddlers. In fact, he went on to say that if anything, what is known would suggest that infants/toddlers are more tolerant of a higher rate of apnea events than adults because they have little negative predispositions such as high cholesterol levels or prior cardiac stress.
What is important to him was the physiologic impact of the sleep apnea, especially if we are balancing it against the long-term benefits of rGH therapy in an infant with PWS. Specifically, he was interested in two physiologic measurements: oxygen and carbon dioxide levels/pressure, and cardiac function. As it turns out, with our son, there was no difference in these two measurements between the first and second sleep studies and so, it appears that we made the right decision to not stop rGH therapy.
However, he went on to talk about sleep and PWS in general. He has about 20-30 adolescents/young adults with PWS under his care and he had noted that with many of these patients, if it were not for the diagnosis of PWS, these patients would be diagnosed with some form of moderate to severe sleep disorder. However, because of the PWS diagnosis, the downstream effect of the sleep disorder, for example, acting out, sleepiness, mild mental retardation, etc, is attributed to the person having PWS rather than to the sleep disturbances.
He speculates that if we take a good look at his patients with PWS and address the fact that they are having very poor sleep and therefore not well rested, we might be able to treat some of these "problems". Minimally, we would create an environment where the patient would respond better to the environment, treatment and PT/OT.
Additionally, we then talked about the impact of poor sleep on infants and toddlers. If the above is also true about infants and toddlers with PWS, then the issue of proper sleep is even more important as we know that proper sleep (not excessive sleep, which actually indicates a lack of proper sleep) is so critical to the development of neuronal junctions and synapses in the brain. He argues that the sleep study should not only be used to address the issue of initiation of rGH therapy, but should be used regularly to ensure that our PWS infants and children are indeed getting the "proper" sleep that they need to develop normal neuronal and cognitive function.
There is no data out there on this hypothesis although we do know that people with PWS are frequently diagnosed with obstructive sleep apnea and other sleep disturbances. This was an interesting proposition and one I think worthy of keeping in the back of our minds.