Nothing you can do - wait till spring and see if they recover. If the stems go soggy, cut back past that point. You may find the top doesn't grow, but new growth appears further down the stem, or from the base. If nothing at all from anywhere by September/october, they're probably dead, but wait till then to decide that.

I have the self same problem Andrea....last year they weathered the snows but this winter has taken it's toll. The smaller one of mine has a spongy stem now, which I shall have to prune right down in Spring...the larger one which must be 20ft, has damage to the leaves but I think the crowns have been sheltered by them....so far the trunk is firm, I am keeping my fingers crossed!