Initially, they weren't able to diagnose it due to the odd cause. Like the article said, mostly this disease is caused by extreme trauma. My father's case was when he cut himself and had to receive a Tetanus shot. About 5 hours after the shot, he was back an the hospital with an arm swelled to twice the size and it's been downhill since. He's actually been to a number of universities for studies, as he's the first documented case to get it from a shot I believe.
He's taken virtually all forms of THC to help, but the only way it is manageable is in addition to the extremely heavy methadone dose and oxycontin as well. Usually he relies on smoking, but pills are sometimes used. Unfortunately, his THC use has increased to the point that's it's insanely expensive and he rarely is thinking clearly any point in the day. It's had long term effects on his mood as well, either from the pain or the heavy drug use (it's hard to tell). He appreciates the THC because it's reduced his dependency a little on the methadone and oxycontin, which were beginning to do severe damage to his memory. It definitely wasn't a miracle cure though, but it's seemed to help.
After 10 years of being heavily medicated to handle the pain, my father too is rarely thinking clearly and has a very poor short term memory.