Answer: Contorted Filbert usually tolerates a wide range of soil types and exposure to sun and except for the dreaded filbert blight, generally has no disease problems. Suckers arising from the roots indicates the roots are healthy (no root rot, etc.) so I'd advise rechecking the stems of the plant for signs of disease. Look for white growths or for tiny black speckles (fruiting bodies of a fungal infection). If you still find nothing out of the ordinary, I'd just leave the plant alone and allow it to produce new leaves. As a last gap measure you can do some light pruning. Sometimes this will shock a plant into new growth.
Wish I had more suggestions!
Q&A Library Searching Tips