Lower Lip Nerve Injury

Q: Dr. Eppley, I have had two mandible reductions and one full lower jaw sagittal split  jaw procedure. These were done within about 5 months of each other. It has been about 9 months after the sagittal split procedure and I still  have a problem with my lips. 

I think the doctor burred too much and now my lip is similar to this.This is the area which has damage. My lip is not quite as bad as this but it is noticeable to a degree. Which part is this? Is it the inferior alveoli nerve damage?  Is it likely that this is going to get better over longer period or is there no chance? When I chew it looks weird and also I dribble always when I drink and sometimes when my mouth is open. Even when I drink from a cup it dribbles from the middle for some reason. Is this type of overdone mandible burring and shaving possible to cause complete and utter permanent nerve death? I have a really tingly sensation if I tap it. It’s very hypersensitive. Some areas of the lip are numb though. 

Would a particular facial exercises help? 

Is there any way I will get back to normal or now not much chance? I worry Botox on other side will just mask problem and not help the dribbling issues. 

A: While you have a lip problem, you are confusing the two nerves that can be affected in mandibular surgery. The inferior alveolar nerve is the sensory nerve that runs inside the jaw and comes out of the bone at the mental foramen below the roots of the first and second premolars. This nerve is at risk in both the SSRO procedure (sagittal split ramus osteotomy) and the mandibular reduction. This nerve is responsible for feeling and is why you have numbness of the lip and chin.

The lip looks like it does because the marginal mandibular branch of the facial nerve has been injured on your right side and is why the lower lip is higher than the left side. This undoubtably occurred during the mandibular reduction not the SSRO. This small nerve is responsible for innervating the depressor anguli muscle of the lower lip (it is a motor nerve) which is responsible for pulling the lip down with motion. When injured it does not move and the normal side pulls down while the paralyzed side rides up, thus creating the asymmetry most seen in activation.

At 9 months after the surgery (injury), while it is not impossible that some motor function of that nerve may return, I would not be optimistic. This is a single fascicular nerve branch so it has no cross-innervation, thus it has a poor recovery outcome. Facial exercises will not help. Botox may be helpful on the normal side so it does not pull down as much.

Dr. Barry Eppley

Indianapolis, Indiana