I know you've heard me talk about sensory issues quite a bit on here, and you may be wonderingwhat in the world I mean. Well, today at physical therapy Super Jane gave me a really good explanation of where all of these "issues" arise. Let's see if I retained enough to explain it all!
Since Jane is a physical therapist, this explanation is from a gross motor perspective, but the general ideas apply throughout the therapeutic disciplines (for Becca, that's physical, occupational and feeding/speech). (Gross motor, by the way, just means big motor skills - walking, crawling, sitting, running, etc. - as opposed to fine motor skills - writing, picking up Cheerios, buttoning buttons. Generally, physical therapists work with gross motor and occupational therapists work with fine motor (among other things).
When we talk about sensory issues from a gross motor perspective, there are basically 3 systems/aspects to consider:
- The tactile input you receive when body parts are touching a surface - for example, when Becca is standing holding on to something, she is getting feedback from the ground under her feet and the surface her hands are holding. This information travels through the nerves and to the brain, where it is processed. At the same time, ligaments in each joint are sending messages to the brain as well (I guess also through the nerves...not sure about that). So when you're standing all the joints you are using (like your ankles, hips, etc.) are noting tiny movements and stretching or contracting to make corrections, keeping you balanced.
- The visual input you are receiving as you look around, helping you orient yourself in your environment. Are you close to the wall? Can you reach out and touch it? What is the ground like? Rocky? This information is taken in through the eyes (duh) and travels via the optic nerve to several different spots in the brain, where it is processed.
- The vestibular system, which, according to Wikipedia, "contributes to our balance and our sense of spatial orientation, is the sensory system that provides the dominant input about movement and equilibrioception. Together with the cochlea, a part of the auditory system, it constitutes the labyrinth of the inner ear, situated in the vestibulum in the inner ear." Got that? Riiight...and that was the easy part of the article! Basically, the vestibular system is based in your inner ear and orients you in your environment and controls balance. That's why you are dizzy when you have inner ear infections, and vertigo is an inner ear issue. Interestingly, the reason the world seems to spin when you are tipsy is that alcohol messes with your vestibular system. Next time you are tempted to over do, remind yourself to be kind to your vestibular system. :) And, like the others, the vestibular system sends messages to your brain to be processed.
Okay, that's how things are supposed to work. Clear as mud?
Now, here's the deal with preemies. The vestibular system is one of the last systems to develop in a fetus, so preemies are born without a fully developed vestibular system. So that's off to begin with. Then this preemie with an underdeveloped sensory system is traumatically introduced to the outside world instead of spending, say, another 12 weeks tucked away snugly in mom's womb. The preemie's immature brain immediately has to start processing sensory input that neither the sensory system nor the brain are really ready for. Think about it - the lights, the touch, the touch, the smells, the cold air - it's a lot to take in, even for a regular newborn. Ever notice that no baby enters the world smiling? So the immature brain has to process everything, on top of all the work it's doing to, oh, keep the baby alive, regulating the heartbeat, respiration, temperature, etc. But then, to make matters worse, these preemies are subjected to all kinds of additional (and necessary) sensory input - intubation, IV's, central lines, umbilical catheters, heel sticks every couple of hours, injections, etc., along with the stimuli we would consider normal but are very abnormal for a fetus/baby this age - even the lights and sounds of the NICU (both of which are intense - think florescent lighting and rooms full of beeping machines and busy people) must be taken in by the underdeveloped sensory system and processed by the underdeveloped brain. See where I'm going with this? All of this taken together basically messes things up. Their systems form a little bit off, and the brain doesn't learn how to correctly process the messages it receives, and it's hard to undo that damage. It's a necessary evil, of course, and when docs and nurses are in the midst of saving and sustaining a life, it's kind of at the bottom of the list, but it sure can leave an older preemie with what we call...drum roll...sensory issues.
Becca's sensory issues affect her in a few ways. We're picking up weekly physical therapy again since she's having trouble progressing because her vestibular system is out of whack (hard to stand and walk without it!) and the tactile messages that she is receiving likely aren't being processed correctly. Same goes for occupational therapy (though we've been weekly with them for a while now.) Also because those stimuli aren't being processed correctly, Becca (as you know by now) can't tolerate certain textures on her hands or in her mouth (or anywhere else, really, but those are the most problematic areas since they keep her from eating), so in occupational therapy and feeding/speech, we work on desensitization, which ought to help her brain learn how to process things correctly. For example, today in feeding therapy we stripped her down, and she played in chocolate pudding. Many toddlers would dive right in and welcome the opportunity to make a huge mess, but for a kid with sensory issues, it's really a challenge. She did great, though! That is, she did great in a relative sense: she tolerated the pudding on her hands and even some on her face for a few minutes, and she even finger painted with it a little bit. No, she didn't actually eat any (I would be all over licking chocolate pudding off my fingers!), but she did better than she has in the past. It's a really, really slow process, so we celebrate even "little" victories like this one.
And that takes me to some good news: the sensory system (and the nervous system in general) is very "elastic," meaning that it can adapt and form new pathways. I know a couple of kids who are completely missing their cerebellum (the part of the brain that controls movement), and their brains have adapted. Crazy. Seriously, our bodies are amazing, particularly our brains. You might have heard about people who are impaired in one sense making up for it in another, and this is why people who are blind can still learn to walk, for example, because their vestibular system becomes more refined and makes up for the lost visual input that is typically needed for motor development. And that's the point of all of this therapy: to retrain her compromised sensory system.
The other bit of good news is that NICU's have caught on to the sensory problems that preemies experience and many have taken steps to attend to "developmental care;" that is, they try to develop protocols that are more gentle on a preemie's sensory system and brain. For example, in Vandy's NICU, they cluster the babies care so that every three hours they change their diaper, take their temperature, adjust their position, and give them any feeds or meds that are due. Obviously they attend to a baby in between, but they try to do all the routine things together so that they aren't constantly disturbing them. Young preemies have thick blanket-like coverings over their isolettes to keep the lights out. (You may remember them from Becca's NICU pictures.) Nurses try to keep the noise level down by limiting visitors and not talking to each other too loudly. They probably do a lot of other things, too, and even some new ones that they have come up with in the past 2 years, but those are the big ones I remember.
Okay, that's all I got. Please leave any questions you have in the comments, and I'll try to address them in another post. And please leave any corrections or clarifications you have, and I'll try to address them in the same another post. :) And because you deserve a reward for making it to the end of this technical post: a picture! Here's Becca trying to orient herself in the space underneath my parents' coffee table. She likes to crawl into small spaces - and there are a lot she fits into!
p.s. It's not too late to make a donation! Help the March of Dimes find new ways to prevent sensory issues in tiny kids like Becca by donating here: www.marchforbabies.org/BeccaHill. To date, we are $645 from meeting our goal. Thanks!