Is it an MS relapse, a pseudo relapse or a flare up?

MS relapse: my idea of what that means is that we know that under the surface in the brain and the spinal cord of people with MS there are episodes where a new patch of inflammation arrives and depending on where that inflammation is it would cause a new symptom. The way that that's experienced would be that people would start to have a new symptom, often evolving over a few hours or a few days until it reaches its worst. Then it would sometimes stay like that for a few days before they start to have any sign of recovery, and then gradually I would expect some recovery to happen over the next few weeks. So I think that's how I would describe a relapse.

Pseudo relapse is meant to is meant to imply that once you have an established area of inflammatory demyelination somewhere in the brain or spinal cord, if that person then experiences something like heat or infection or stress there's a risk that the old symptoms that were originally caused by that same patch of inflammation might flare up. 

The implication of a pseudo-relapse is that we're suspecting that there hasn't been a new area of inflammation but we're suspecting that that old area has just made the patient a little bit more vulnerable to re-experiencing those same symptoms when something else happens. I think one of the reassuring things is that it should get better and and it doesn't always imply that your disease is fallen out of control. It might just be that there's been no change on your scans but you've just re-experienced some symptoms because of something else that's going on in life.

Some people use MS flare-up to mean the same as an MS relapse.  I think it is open to interpretation, but I think one of the good things about this term is that it recognises that not all worsening that people experience in MS is due to a patch of new inflammation. 

Sometimes there can be other reasons for that, so I think an MS flare-up is a little bit more encompassing of all the reasons why someone can transiently feel worse in MS. They could include, apart from a relapse, they might include a pseudo relapse, they might include side effects of a medication. It might be that there's some fluctuation in symptoms such as fatigue, such as spasticity, that are just a little bit worse at that time. So that might relate to all sorts of things like stress levels, sleep deprivation, and you know other things that are going on in life. I think a flare-up can really be all-encompassing of that.