Fluctuating temperatures can affect plants in many different ways so I would recommend doing nothing until mid-May. By then, all stems that should leaf out should have done so. If you just cannot wait another microsecond, you can prune the stems from the top downwards in 1" increments until you see indications of life or until you get to the bottom of the stem. Keep in mind too that, although the drought could have killed stems, the roots may be fine and the roots will create new stems from the base or crown of the plant.