This Myth has been around for quite awhile and has caused some schools to wrongly stop using cold packs for bumps on the head.
I think the myth comes from the mistake not to put pressure on the skull in case there is an underlying fracture. But you can apply a cold pack without applying pressure. Also did I mention that the skull and facial bones are very hard and are designed to protect the brain which is soft. Remember ice should never be put directly onto the skin but use a cloth. Also Ice or cold packs should be applied roughly thirty minutes on and thirty minutes off and then repeated.
I will be adding head injuries on here soon so keep checking back.