Die back of maples by branch or in larger sections is often attributed to Verticillium wilt. This is a soil pathogen to which maples are very susceptible. It is present in most soils but usually in a dormant stage until stimulated into life by some sort of mechanical injury or major stress factor. These can include such things as unusual weather occurrences, drought, poor drainage and root disturbance.

IME, VW is pretty much fatal and rather rapidly so and replanting with another maple or VW-susceptible species is not advised, but I have read of occurrences where the trees can survive for a number of years with the affliction. The only way to be sure is to take a sample into your extension service office or other plant pathologist for diagnosis.

Here is a link that might be useful: Verticillium wilt