head injury - can anyone help ease my fears numbness around the wound?

my partner was hit on the head with a bottle on sat night by some random hooligan he went to hospital and they glued the wound and put paper stitches in and sent him home, now he says he has numbness in his scalp (like if i pulla certain part of his hair he cant feel it) is this normal due to the trauma or does this spell something serious - i over react and just need to settle my mind - he is such a quiet man and i am worried out of my head as it is about the whole incident thanks in advance for any help