Can someone please explain why some people have loads of lesions but have little in the way of disability. But then others only have a few or no lesions and can be very disabled? I ask this as the main tool Nueros use to Dx MS is the MRI, and this seems strange in view of the above.
I don’t know much about it but my understanding is that the lesions show evidence that your nerves are being damaged which is what ms is. However the extent you are disabled depends very much on where the damage occurs. It could be that you have lots of damage occurs(lesions) but that they have limited effect on you physically as the are not near nerves that control your physical movement. For example i have 11 plaques but until very recently only suffered from a numb face and a funny arm. Not sure if my explanation is that clear but Im sure others with more knowledge will fill you in on the science behind it!
As Sheena has said, it’s where the lesions are rather than how many there are or what size they are that matters.
A lesion in white matter is often easy for the brain to deal with - it finds a new route or manages to work with what’s left. A lesion in gray matter is much harder, but the neighbouring gray matter can often take up some of the slack. Plus, the brain tends to work in networks, with multiple areas involved in doing the one task. If one bit is struggling, the other bits can sort of work harder to compensate or the brain might recruit new areas to help out too. This kind of thing means that a lot of MS lesions are “clinically silent” in that they don’t cause any noticeable symptoms, and is the reason that we go into remission (as our brains get on top of the inflammation and learn to cope).
If a lesion happens somewhere that is very specialised, then the brain can’t work around it so well. For example, while the body is pretty good at repairing the optic nerve, repeated attacks of ON will often cause some degree of permanent loss of vision - there’s just no way to work around it. There are various specialised areas in the brain - some of these are absolutely fundamental, e.g. for breathing. Thankfully, MS rarely wipes these out, but it can and does happen - and it could happen in someone with hardly any lesions - it’s a bit like Russian Roulette, but with billions of empty slots in the gun barrel. (And I mean billions.)
Spinal lesions tend to cause more disability than brain lesions because there is less wriggle room in there. If you imagine the spinal cord as a motorway and a lesion as a car crash - all the cars have to try and go past in one lane or they are stuck completely until the crash is removed from the carriageway.
Another main reason is probably that there are two main processes going on in MS. Lesions are the obvious one: this is inflammation and is partially repairable. The other one happens at a much smaller scale and causes the death of nerves. Once a cell is dead, it cannot be repaired. This is the process in progression.
And finally we have the very strange fact that some people’s MS tends to be mostly motor-related and other people’s MS tends to be mostly sensory-related. Someone with motor-based damage may be unable to walk. Someone with sensory-based damage may find it too painful to walk. Both things are disabling, but for different reasons and while the sensory damage may be helped with meds, motor damage cannot.
I may have missed something, but I hth.
Karen x
Brilliant explanation Karen thank you, I never knew any of that!
What a really clear and well written explanation Karen.
When I had my MRI scan nearly two years ago I had at least thirty lesions but all in the white matter. So compared to some people I have relatively little disabilty at the moment. Lots of pins and needles, muscle pains and ‘dead’ right arm and leg. One of the first symptoms I had was a numb face. I’ve never had a spine MRI so no idea what’s going on there. I don’t suppose it would make any difference to find out anyway. I’ve got a diagnosis of RRMS. All of my lesions were not typical of MS so I had to have a lumbar puncture to confirm the diagnosis.
I do wonder though, how long between the lesions occuring and symptoms showing? I look back over the last 10 years or so at various things that happened and now wonder if that was part of the MS?
Lynne