Aphids, winter damage, leaf curler insects and insecticide/fungicide damage can cause leaves to curl and deform. Search for insects day and night; use an insecticidal soap or spray if you find aphids. If you unfurl the leaves and find insects/worms, you could remove the manually or apply some bt this year and next. Insecticide/fungicide damage requires that someone apply them recently nearby and then the wind spreads them to the hydrangea; the damage can be pruned off.