I'm 55 and about 3 months ago, out of the blue, my left bicep and triceps began to twitch vigorously pretty much non-stop for a few days. Began to taper off after about a week, but would start up again and last for hours. Was waking me up and making it difficult to focus. Spoke to my PCP and she ordered a bunch of blood work to rule out something simple. Everything came back "normal" which was surprising to me.

Went to a neurologist and have to say when I was sitting in the waiting room I was in full panic attack mode (BTW, I am considered to have panic attacks after a bout of cardiac issues a few years ago that turned out to be caused by hyper-functioning thyroid), heart rate was off the charts, BP was extremely elevated, and I was sweating profusely. Could barely speak when I got to the exam room as I was sure I had ALS. Neurologist performed a pretty thorough physical exam and gave me the same diagnosis as many have stated above: no signs of weakness, atrophy, or any other obvious issues. Probably anxiety (prescribed an SSRI), could be BFS, and suggested an EMG/NCV exam. Felt better immediately after the exam. The SSRI makes me have other weird sensations, but in combination with meditation and mindfulness, has helped a lot. EMG/NCV results came back normal (actual statement was "perfect") and was sent away with suspicion of GAD/Panic attacks and scheduled a follow up for December.

A week after the EMG I sprained my left wrist, got some cortisone shots, and told to wear a splint for ~ 8 weeks. Forearm muscle shrunk a bit (as it has been immobilized by the splint) which triggered "atrophy" in my mind. Twitches came back with a vengeance all over my body. Arms and legs feel week, pain/discomfort that doesn't respond to NSAIDs, and I just feel terrible. Interestingly, when I am busy doing something I don't notice any twitches or discomfort - when I stop and look at my arm everything starts up again.

I am a true believer that anxiety and stress is a major factor. I strongly encourage everyone with symptoms to pursue testing with a healthcare provider, but in addition to many of the things mentioned here, good mental health practices are important. Mindfulness and cognitive behavior therapy are very helpful. Once you get answers from a physician who has done due diligence, it is importnat work to accept the diagnosis and come to believe what you have been told. If you truly have a condition, it will continue to manifest itself. However, if it is stress and/or anxiety, controlling that can have a major impact on quality of life. Be an advocate for yourself when you go to the doctor and continue with routine follow ups, but also be an advocate with yourself and remember that most of the most horrible and serious conditions that are associated with fasciculations (e.g., ALS, MS) are also relatively rare. Don't do searches on Google; Dr. Google didn't go to a good medical school. This is easier said than done. If you are going to go on the internet, look for things that can help you feel better. Learn about managing stress and anxiety. If you want to read about conditions, use Google Scholar and get peer-reviewed research papers and read the entire paper.

Finally, be careful with supplements/vitamins/minerals, etc., unless you are followed by a physician and tested regularly. You could end up doing more harm. Prescription drugs are required to disclose potential side effects, most supplements are not, nor are they studied rigorously.