My DD, Charlotte, has a facial palsy that has largely recovered. A facial palsy just means that a nerve or nerves in the face are paralyzed for one reason or another - and it encompasses a large range of diagnoses and conditions. Sometimes it can completely cosmetic and effect only a small area of the face, other times it can hinder a child's ability to do things like eat, talk, and blink and they might have problems with drooling.
Charlotte's face droops on one side. The plastic surgeon and neurologist think that she had a nerve damaged in the womb or during delivery. When she was little - up until about a year - it would often look like she was biting her lip when she wasn't actively engaging her face with a smile (see PIP). She never had any problems with eating/sucking/drooling, etc.
In the last year, she's had EMGs that showed that her nerve is recovering and her drooping has become much better - although it's still noticeable when she's tired. It's pretty much unoticeable to non-medical personnel when she's smiling/talking/actively engaged. My guess is you can't tell at all from my siggy photo below.
Before it became apparent that her nerve was healing, we had talked about surgical options that were pretty serious stuff (taking nerves from a muscle in her leg and implanting them in her face). My understanding is that most of the time surgery isn't recommended until about preschool age or older, simply due to the fact that the nerve may recover.
With Charlotte, we just have yearly appointments now with the plastic surgeon to make sure that she's not back tracking. The plastic surgeon thinks that she will never have a truly even face b/c even though the nerve is recovering, a few of the conductors that send the message to the muscle to work may have died. But he said that it's unlikely that we'll want surgery for her in the future - but that she may decide at some point to do something minor like botox to help even out her face if she wants.