A friend of mine had an accident riding his bicycle, he grabbed a nearby railing and his pectoral muscle was torn completely from the bone. Unluckily when he saw a doctor here he was prescribed massages and told that it would recover in a few weeks. After several months he had an MRI, but again unluckily they took the MRI of his stomach rather than his shoulder/chest.
Anyway, long story short, six months after the injury he went to the states and got surgery. He told me that because of the length of time before treatment, he is in real risk of losing all feeling in the arm: something like the nerves are under constant tension and could snap at any moment, particularly if he over-uses the arm. And since he's a BJJ guy, it's somewhat likely that he will do just that.
Sounded scary, anyway.