Thank you for sharing your pictures with eXtension.

There are many causes for your spruce's problems. This article from Michigan has an excellent description of each, as well as some pictures: http://msue.anr.msu.edu/news/what_is_spruce_decline_and_what_should_you_do_about_it.

If the dying branches are only found at the top, I would consider one of the canker diseases to be the cause.  Unfortunately, there's not much you can do other than prune out the diseased wood.  Cutting the top off a spruce might save its life, but I think that the resulting regrowth might ruin the cosmetic appearance of the tree.  I would suggest contacting a local arborist (check the yellow pages) to see if someone could get up into the tree and examine the diseased area.