I am afraid I cannot be much help.

The resolution of the images let me take a fairly close look, and I saw nothing that gave me clues.  Of course the relevant clue may not be visible even if I had it in hand. 

It is an odd pattern, fairly vigorous branches that have seemingly died, or are dying.  Yet there is some pretty healthy looking growth farther out on the branch.

You did not include a broader image.  How much of the total crown is affected by this? How much of the crown was lost in the ice storm?

Thanks for your quick response.  We estimate about 1/3-1/2 of the crown was lost with the ice storm and the post storm clean-up. It was mainly from the left side. It lost a large towering limb that used to be between the new growth on the left of the picture and the dying off part on the right. Here are a couple more pictures showing the entire crown of the tree. The new pictures give you an idea of how much of the crown is affected. This has always been a tall, gangly tree. Anyway, we figured it was a long shot that you could help, but felt it was worth a try in case there was a lot of this going on in the area. Otherwise, it's just our poor tree. Thanks so much,

That is a lot of damage, putting the tree out of balance with its roots.  So not entirely surprising that it is struggling.  But its not dead yet, and not clear that it will die.  What you choose to do may depend on where it is in your view shed, and certainly proximity to house and other infrastructure.

Good luck.

Thank you for your input. We'll let our arborist know what you said about the tree being out of balance with its roots. He's already talked to us about the importance of a healthy root system. We'll see what he can do to save it. But ultimately we may just need to take it down. It stands next to our driveway at the front of our property. We sure appreciate your help.