Regarding the meds: I was a bit anxious when I posted my question and just now when I went back to reread it looks like I was almost asking for heroin or something

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For me it totally didn't come across as that.
That is NOT at all what I meant to sound like. His doctors know we are going and I meant I was wondering if he should talk to them about something additional just for the flights, but now that you mention it he WOULD need to try it out beforehand to check it's effect. I mean, we wouldn't sedate our pets; it's no safer to sedate DH right? So thanks for pointing that out.
Don't wonder about talking to the doc; DO it. Together you can evaluate if changing his meds for the flight (or perhaps maybe even right before it if for instance it are meds that he needs to built up a level off before having the best effect) might be an option. Try out to see how he reacts to it, which again also is something that together with doc you can decide if it's worth the "price" (read side effects, possible risks etc.) for the "gain" off them.
Think about what helps him painwise and how this could be reached. Some might turn out to be medicinal, others might be aids or mindset. For instance changing his level of activities in the days prior to flying so that he doesn't start out on a level "on the edge" where pain will hit him harder and sooner.
You know, medications come in all shapes and forms and it doesn't mean you will sedate him. First up; he's an adult and I assume he's of sane mind. Unless you sneak him something, that wouldn't be you sedating him to begin with.

Besides that I'm an avid believer that sedation isn't an effect one wants on a flight. Odds are in favor of you, but what if you hit the jackpot and need to evacuate the aircraft a.s.a.p with a sedated adult? Not the smartest move, so to say. One of the many reasons I'm so pro trying out meds before inflight. Also remember; up in the air one might react a bit more intense to medications, just like one does to alcohol.
It might be an option, might not be. That's up to husband and doc and secondly you as a partner if you are willing/able to travel with him like that. I personally always alter my meds for a flight and also alter them for a "stay" during a trip. Inflight are aimed towards making the flight a bit less of a hurdle and the "stay" chance is aimed towards having a temporary slightly higher level of "ability" then in daily life. The latter as a direct result in wanting to be a bit functioning while travelling but knowing it is not an option for daily life as that bit of extra painmanagement does come with overdoing it that bit more and for me overdoing it too that extend does come with a permanent loss of "ability" I will have from then on. It's a balancing game as it always is with any medication.
Guess thats one great point for the list to consider; if DH meds are changed and his pain is temporarely managed otherwise, could that come with a risk of overdoing it? And with which risks would that be? Would that be worth it for him and you?
Also, I did NOT even think about the transfer. How could I forget that! We planned for dme. I'll try to find out if he can stand for that. He's much better standing on the busses or sitting in the backs where there are many seats in a row.
We all forget things, you're just human. I'll give you one to laugh about; my first trip ever to WDW was a solo trip (as many are) and my first ever trip with a powerchair (had done some with just manual chair). I checked all details and got all my ducks in order, incl. most small things. Forgot one rather huge thingie.......... the battery charger. I brought it, I brought a "world plug" but totally forgot about the 220V in Europe versus 110V in America difference. Sure enough; couldn't charge my powerchair, which is kinda...... well....... problematic.


End of the day Disney took this moment to shine and took care of it and let me enjoy 9 magical WDW days which would result in many more trips and a confidence that whatever might happen, I'll be OK in the end.
Sitting in the back is easier? Funny! I've found there is a lot more movement in the back on the style of busses used for DME. On the other hand; it might be a benefit as most people will want to sit up front which would give good odds for a seat in the back. Can DH stand in line and wait? The lines for DME are standing and can take a bit before you can get on the bus sometimes. If not; there is a (hard wooden) bench used for instance for those travelling with somebody in a wheelchair (who don't wait in the regular resort lines). Explaining his situation to DME CM's should probably do the trick to let him wait there while you wait in line.
I'ld advice reading Sue's sticky about the DME. It has great pics about the stairs onto the DME so DH can see if he can manage that after a flight. And have you considered the shuttles that go from gate to the terminal at MCO airport? Again something that can jerk when leaving and stopping. There are polls to hold onto, but no real seats. Getting very detailed now; how about waiting around the airport before you can board? Doable for him or also something to factor in?
I'ld try out some cushions for DH to absord some of the motions. Not only can he benefit from it at home (car etc.) but it could be a help on the plane, on the DME, the bus to the park (again hard plastic seats and jerky ride, that is if it isn't standing room only by then). I'm very avid for not "just" taking anybodies word for something as so many individuals, so many different needs, likes etc. Take out time for this and give stuff a trial run. Find out if foam, memory foam, standard, form fitting, shaped, angled, airsystem, whatever of the many options out there work best for DH. For instance; I totally

for air as it constantly adjusts itself to my ever changing body and absorbs the way I need. My friend on the other hand with the same condition does much better with memory foam. Trying really does pay out with this. Where possible, try something out at least for a longer time if it seems to be a succes. If it turns out to be something that is great for 15 minutes but then tortures him more than having all his nails pulled out, he'll find that out before spending money on it.
Doctors still haven't diagnosed what's causing the pain, although they believe it is related to nerves in his spine. It causes back, leg, abdominal pain like a fist with electricity. It's hard for him to describe to me. He's had so many tests and treatments and pain clinic appts and has two more appts this coming week. He goes to a university hospital as well as team based specialty hospital and they coordinate. What they've both told him to prepare for is that only 5% of people in chronic pain get a firm diagnosis and resolution. 95% learn to manage. And he does manage so much better than he did 6 months ago.
Yep, that's the thing with chronic pain. Much more often than not a diagnosis will never be found. Even if it is, it's not a good odd that this will come with a removal of chronic pain. It's a hard path to walk and often you as a partner and kids are even more overlooked when it comes to seeing the effect it has and having some support for it. Realise that and be your own advocate with that.

If he hasn't had the option discussed or metioned yet; there are some great pain management programs out there that will focus on learning to LIVING with chronic pain instead of just surviving. They are allround programs that tend not to look into healing or diagnosing but offer all kinds of specialties. Physio, occupational therapy, hydrotherapy but also looking into how work impact this and what can be done on that front, impacts and options with regards to sports and hobbies, impact on ones emotions etc and not in the least; also offering some support for the partner as it's also a life-changing thing for them. They aren't curative but results when it comes to how one views their quality in life afterwards are very positive for high number of participants.
Either way; have an amazing trip!