In either case, approval or denial, Social Security will notify you by mail as to their decision. The state disability office in which you live processes your claim. They will review all you medical records pertaining to your conditon. It is very important that you send all records including the most recent office visits or hosptializalions.
Usually, a decison notice is sent within 90 days when you first filed. If you are approved you will be sent a letter stating what benefits will be paid.
You will always receive an official written notice regarding the decision of your case, but you should check the status of your claim occasionally to make sure a decision has not been made to avoid the risk of having your sixty day appear period lapse.