ELI5; How do central nervous system disorders work? For example, why does fibromyalgia make it impossible for an otherwise healthy 29yr old unable to open a bag of chips?
In: Biology
Speaking broadly, central nervous system (CNS) disorders happen when your brain or spinal cord do things they aren’t supposed to do, whether that’s sending out too many signals or not enough signals. Here, you should be thinking things like stroke, Alzheimer dementia, Parkinson, epilepsy, and multiple sclerosis. With these, there is actual structural/chemical problem in the nerves leading to the symptoms. We can see those changes with imaging, lab work, and nerve function studies.
Something like fibromyalgia is not really a CNS disorder in that sense. We don’t really know why fibromyalgia happens, but what we do know is that there is no real identifiable underlying nerve problem seen. The most common presenting symptom of fibromyalgia is long-standing, widespread pain.
To further drop some knowledge bombs on fibromyalgia:
– it’s sometimes associated with other chronic pain conditions like IBS and chronic pelvic pain (interstitial cystitis)
– stress is usually a trigger, which it’s why it’s often associated with depression and anxiety
– there’s not really a good treatment because we don’t really know what’s going on.
Source: final year medical student
Think of it like a captain commanding a bunch of workers to haul some very large thing by collectively pulling on a rope. Captain = brain, command = nerve signals, workers = muscle fibres. I’m currently visualizing this [scene](https://www.youtube.com/watch?v=zpgiw1i94Io) from Les Miserables.
You may technically have enough workers (muscle mass) to haul the large object (open a bag of chips) but if only a few of the workers hear the command (get properly signaled through the nerve cells) only a few of the workers will be working towards the goal and the rest will just be sitting around not contributing, or getting confused and doing something that is unhelpful to the task at hand. The task cannot be completed without more of the group working in unison.
To take it further, if the workers repeatedly do not hear the command because the chain of communication has deteriorated long term, the workers themselves get weaker (muscles atrophy). Later down the line, even if the line of communication is repaired (nerves healing or becoming less inflamed) the previously non-contributing muscles are too weak to contribute meaningfully even if they are trying to. For this reason, it can sometimes be hard for people with nervous system disorders to maintain muscle mass/muscle function long term.
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