Hi EL,

I understand how you could be worried aout your husband.  Let's see.

An electric wheelchair for someone with PPMS is not unusual after six years.  The weakness is quite common in MS.  Based on what you said, I would not say he is in "final stages," but your doctor can give you a better idea.

I did not find a life expectancy for apnea, but serious apnea can result in a heart attack.

As far as a relationship between MS and apnea, both have similar symptoms.  For example, both lead to depression and a sedentary lifestyle.

I don't think this is exactly what you were looking for.  Perhaps someone else has experience and can give you a better answer.  Good luck to both you and your husband.