I never really received a firm diagnosis, but I can tell you that I've regained a significant amount of strength (~80%) since the initial episode. The fact that I did regain strength gradually over time without any strength training, combined with the length of time it took to regain the strength, leads me to believe it was some type of neuritis caused my trauma to the brachial complex. I still get fasciculations in my right triceps & chest every so often, but they've decreased considerably -- both in terms of frequency and intensity.

If you're going through something similar, would just suggest an ample amount of rest. Like I said in my initial post, it took a solid 5 months of abstaining from weight lifting or contact sports to recover an appreciable amount of strength, which makes sense given a nerve regeneration rate of 1"/month.

Hope this helps!