Dr. Bullen: When I think of cachexia, I think of the loss of lean muscle mass associated with an active disease state. So, it tends to be more of an active process. Typically, it’s associated with increased inflammatory cytokine circulation. Oftentimes, it’s associated with an increased energy need, depending on what it is, but you get this increase in lean muscle mass breakdown, whereas sarcopenia tends to be loss of lean muscle mass associated with age, and that sometimes can be due to an increase in inflammatory mediators, but a lot of times, it’s inactivity. You can have both; you can have a cachectic process and also age-related sarcopenia. Sarcopenia is not ideal, but cachexia is more alarming and more important to really try to get a handle on, if one can. It’s very challenging to support the patient appropriately.
Dr. Larsen: Dr. Bullen, do you think that the distribution of muscle loss in a particular patient helps determine the underlying cause?
Dr. Bullen: I personally do. When I think of some age-related changes, especially if it’s associated with inactivity or disuse or things like that, it tends to be the muscle that they should be using to ambulate and mobilize. When I see muscle loss associated with cachexia, it tends to be the muscles you wouldn’t necessarily see associated with disuse—the temporalis muscles, the epaxial muscles, things like that. So, when I’m assessing a patient for muscle mass scoring or muscle mass indexing, I’m looking at everything but also assigning localization. I’ll say moderate muscle wasting, generalized, and if it’s truly generalized, that worries me if it’s all over. If I see moderate muscle wasting for a limb and normal muscle mass everywhere else, we really need to be isolating that limb, seeing if it is disuse, if there’s an injury, that sort of thing. So, yes; localization and distribution can help me determine if it’s more likely to be sarcopenia versus a cachectic process. By the time they get to me, I usually know that they have a chronic disease state in which cachexia is more common or likely, so it’s already on my radar.
Dr. Larsen: For certain patients, I’m often looking more at the musculature on their head, those temporalis muscles and such, because we see so many geriatric patients that have some degree of degenerative joint disease, so maybe their pelvic limbs are atrophied and sometimes they’re not symmetrical because we know they have an injury on a side. Then sometimes the patient’s conformation or maybe their underlying orthopedic disease makes the epaxial muscles really difficult to determine, if the spine is just prominent, or if the muscle is atrophied or both, due to ankylosing spondylosis. Sometimes it’s even harder when they have a layer of adipose on top of those muscles and you can’t palpate easily, especially in that location. Most of our patients are geriatric and have multiple comorbidities.