The injection of botox or similar products into the masseter is a popular and safe way to contour the lower face making it less square. In addition, if you tend to clench or grind teeth, this can be reduced with masseter injections. Proper technique is essential as...
There are a lot of sensory nerves in the face and yes, what you are describing, a feeling like an electrical pulse from the site up into your head, is exactly what happens when a nerve is affected. I have never seen this be permanent, but I have seen it take up to about 6 months to resolve fully...
Your question is an excellent one. When I inject "baby botox" it is more of an art than a science. I generally reduce the number of units placed and distribute it in a "softer" way so as not to "freeze" the wrinkles altogether. If you would like to post a photo I can more reasonably tell yo...