It’s a cliché that you don’t appreciate something til its gone, but in the case of one-sided facial palsy, one half of your face is a constant reminder of what you used to have: symmetry at rest, facial expressions, blinking to keep your eye moist, and resting tension in your lip muscles to keep you from drooling.
Bell’s palsy in particular usually resolves, and so most of the facial functions return, but if they don’t, or you have some permanent injury to the facial nerve (through trauma or after tumor resection), or you’re born without functioning facial nerves (hemifacial microsomia, Moebius syndrome) there are ongoing problems.
The details and options for these kinds of reconstructions are too varied and extensive to go into here, but I’m glad my training allows me to help in these situations.
One of the last cases I did as resident involved transferring a muscle and nerve from the inner thigh to a little girl’s cheek, so we could restore her smile. It takes some time for the nerve and muscle to work in their new environment, but I was happy to hear 6 months later she was starting to smile . . .