I developed weakness and winging in my left shoulder 4 months ago. I was diagnosed with the LTN injury. EMG did not show anything.
I am convinced the diagnosis was incorrect though and my symptoms are due to lower trapezius weakness (accessory nerve).

After 2 months my symptoms started improving slowly. But recently I developed the same problem on the right side. Ugh. Doctors just shrug their shoulders so I am scheduled for another EMG.

From what I read about the LTN injury, if the nerve was severed, it may not recover without surgery. If it was simply compressed, it usually recovers on its own though it takes a long time.
The surgery may not be beneficial long time (after 1 year) after the injury.