Help with SINGLE frown line, not a number 11. It is 1 inch long. Plastic surgeon said it was a split muscle & should be removed?

I understand your concern! Usually Botox is the silver bullet for such a problem, but it doesn't always work when the muscle is as thick as yours. If the Botox treatments are effective, that remains your best option. If less than effective, Botox plus filler, or a more aggressive approach would be direct excision of the line and debunking the muscle through a more "open" approach. Less chance of complications, like bleeding, but you are trading for a permenent, yet probably unobtrusive scar in the region. Seek the advice of a board certified plastic surgeon.

Your frown line is not due to a split muscle. It can be treated without surgery, using a combination of Botox, fillers, and laser resurfacing. Your line is due to the activity of the corrugated muscle, which over time has weakened the collagen structure under the skin. It is important to first weaken the muscle with Botox or Dysport. If this still leaves a dent, then fillers should be used next. Once filled, if you want to improve the texture of the skin in the wrinkle itself, a resurfacing laser will be very helpful

Just adding a filler won't do much since the skin is adhered down tightly. Subcision followed by an implant to permanently fix the problem is 1 solution.

I have successfully treated these lines for over 10 years using fillers.  Surgery might not be the solution.  

Botox will reduce the movement in the area and your ability to frown. However, the fact that your line is marginally better when you relax suggests that Botox won't correct this on its own. A dermal filler can be very effective in combination with Botox to fill the line and prevent it from recurring by relaxing the muscle. If you're having a browlift, the muscle can be divided but I wouldn't recommend that unless you're already planning to have browlift surgery. Best. Stephen Weber MD, FACSDenver Facial Plastic Surgeon