In a previous post I talked about dysphagia and why a thorough evaluation should include imaging. So what does that mean? The most common type of imaging done in this area is the Modified Barium Swallow Study (MBS). This is different than a “Barium Swallow” but is sometimes confused during the ordering process.
An MBS is conducted in radiology by an SLP, with a radiologist or radiology technician present to run the equipment. We conduct the test using fluoroscopy which is a moving x-ray. This allows us to watch you swallow in real time to see what your swallow really looks like, and what is really happening in there. I happen to think it’s a pretty cool test! Here are a couple of videos so you can see what it looks like!
During the test, the SLP or the rad tech will feed you various textures mixed with barium. Barium is a white material that shows up on an x-ray, and we mix it with food so we can watch what happens when you eat the food. Depending on the test, you may be given thin liquid barium, and various other thicknesses of liquid mixed with barium. You may be asked to drink them from a spoon, a cup, and a straw to see if the amount of liquid changes the swallow. Babies will be given a bottle containing barium mixed with formula or breastmilk. You will also be given various textures of solid mixed with barium paste, usually a cookie, fruit, and a puree, like applesauce or yogurt.
The most common misconception about an MBS, is that it is a “pass/fail” test, that if you don’t aspirate, you pass, and if you do, you fail. Really, though, its not that simple. SLPs are looking at multiple features of the swallow. In my post “So what is Dysphagia Anyway?” I referred to the three phases of the swallow, oral, pharyngeal, and esophogeal. It happens quickly! Each phase is watched closely, with each texture, for anything abnormal. Here are some important things we look for in each phase:
Oral phase- lip closure, biting, chewing, tongue movement side to side, back to front, and up and down. We watch for the “bolus” (the bite/sip of food/drink) to be chewed and collected together, to move appropriately to the back of the mouth for swallowing. We also watch for material to fall out through the lips, get stuck somewhere in the mouth, or fall down the throat before you are ready.
Pharyngeal phase- this starts when the bolus goes “over the cliff” or down the base of the tongue and into the throat. We watch how soon the swallow triggers, and where the bolus is that causes the trigger. We take note of tongue base moving back, and the entire larynx (often called the voicebox) to move up and slightly forward, the epiglottis to invert (or flip/close down) over the airway (my patients love to talk about getting the “flapper to flap”). We watch for material to stay in the spaces known as the valleculae or the pyriform sinuses. And of course we watch to see if any material goes to the vocal folds (penetration) or into the airway (aspiration), and if the patient responds to clear it out.
*Now I’m going to stop right here, to comment, because this is hugely important. The biggest reason that an MBS is of utmost importance is that sometimes a patient does not respond when they aspirate. The vocal folds sit at the top of the airway, and close to protect it when we swallow. These vocal folds have very sensitive nerves that hate material touching them. When food or liquid touches the vocal folds, the normal response is to cough like crazy. This is the body’s way of clearing out anything that gets in there. This is why it is so uncomfortable for something to “go down the wrong pipe!” Sometimes, because of a stroke, or another event, a person with dysphagia doesn’t sense this aspiration. This is called “silent aspiration” and is a dangerous scenario because material can go down the windpipe and into the lungs where it can do all kinds of damage. This is also why we can’t know for sure if a person is aspirating unless we SEE IT on an MBS.
Esophogeal phase- this is only viewed during the MBS as the ending of the swallow for us. While we really don’t treat the esophogeal phase, what we do above can affect it, and what happens in this phase can affect what happens above. We look for things like material sitting on top of the Upper Esophogeal Sphincter (UES) that opens to the esophogus, backing up into the esophogus or back up to the airway, or falling into a pocket and staying there and any other thing that looks abnormal. If this happens, it could cause symptoms such as coughing or even aspiration after the swallow is over. These are important findings that would cause us to refer you to a gastroenterologist (GI) who assesses and treats this phase of the swallow and below. This is also why we can’t just assume coughing is aspiration, we can’t know why you are coughing unless we see it.
MBS for infants is completed using only the textures which are age-appropriate. The phases look a little different because a baby’s anatomy is slightly different but the SLP will look at the suck-swallow-breathe rhythm and, similarly, will look for aspiration, under what circumstances, and if the baby shows any response to the aspiration. Babies responses are different, and when they aspirate it is often silent, so we need to know to look for other signs the baby may be giving us, and we can know what those are from seeing them on the MBS.
You might think that the MBS is only diagnostic in nature, but here is the cool part of the MBS. During the MBS, if the SLP sees anything abnormal, they make a quick decision as to what might make that better based on our knowledge of how the swallow works, and what is causing your particular difficulty. We may have you tuck your chin down, alternate liquid with food, or swallow twice. We may change the positioning of the baby, or the flow of the nipple. We may determine that you swallow more safely with thicker liquids, or even that you do better with thinner material, with smaller or larger bites, or with cold liquid. This is where the MBS is really so valuable for therapy! We can watch these strategies and changes and know what they do to YOUR swallow. Your treatment plan should be personal to you! For some people, a chin tuck, or thickening liquids are great strategies, and prevent aspiration. For others, they make the swallow worse or do nothing. Knowing this information is absolutely invaluable for making treatment decisions because we only want to change what will actually help you. Thickening your liquids without knowing it helps doesn’t make a lot of sense. I will talk more about diet texture changes, and swallowing safety in future posts! In the meantime, talk to your SLP about your, or your loved one’s, MBS. Ask what it looked like, and ask them to explain the treatment plan, and what you can do to carry over the treatment outside of therapy. Trust me, we love to talk about this stuff. The more you understand about your swallow, the better equipped you are to improve it!
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