Thanks for writing in.
A cut finger nerve can be missed immediately following the injury. The cut may be closed in the emergency room before numbness
is recognized. It is possible that he still has some internal swelling causing nerve compression - if this is so, the numbness will go away once the swelling comes down. If the sensations do not return with time, it can be a severed nerve injury
. As pain decreases, numbness can become more obvious and requires a visit to a hand surgeon.
Hope this helps