Why is there such a focus on the lip? I have several theories:
1) It's an easy structure to evaluate.
2) Many parents and practitioners are confused about the difference between a normal labial frenulum and a lip tie. I've written about that previously.
3) The procedure and the recovery are relatively easy. The stretching exercises for the lip are well-tolerated and the reattachment rate is extremely low.
Wouldn't it be great if such a simple lip procedure took care of so many problems? I do think that the upper lip plays a role in normal breast-feeding. With a lip tie, the child has difficulties flanging the upper lip, and this can cause muscular tension that can make opening the mouth widely very difficult. The result is a shallow latch, a small mouth (baby can't open widely), nipple pain and nipple trauma. In my experience, if a baby comes to my office with breastfeeding problems and has a tie, 99% of the time that child will have a tongue tie. They may also have a lip tie (about 50-60% of the time) accompanying the tongue tie but isolated lip tie is very uncommon - it makes up less than 1% of the babies that I treat. Those few babies have normal tongue function; the lip restriction is the only obstacle to achieving a normal latch. For most babies, however, a tongue restriction is the problem.
Why do I think that the tongue is usually to blame?
1) The tongue is the active muscle in breastfeeding. It is responsible for the creation of negative pressure that is necessary to nurse normally. The lip, on the other hand, is a relatively static/passive component of normal breastfeeding. It can get in the way, but a normal lip doesn't guarantee normal feeding. A normal tongue, on the other hand, is much more predictive of normal breastfeeding.
2) Almost every published paper demonstrating the benefit of frenotomy on breastfeeding included patients who only had a tongue tie release. Most ignored the lip. Despite ignoring the lip, the available evidence shows that lingual frenotomy alone was beneficial.
3) When the tongue is tethered, it can affect the lip's function. If the tongue does not form the peristaltic wave necessary for vacuum generation, the baby can forcefully try to suck the breast in. This can cause the upper (and lower) lip to get sucked in, again causing the mouth to stay closed. This can mimic a lip tie because many people equate a rolled-in lip with a lip tie when it's really the tongue's fault. Think of the lip motions necessary to use a straw: the lips must purse with strength to hold suction. In people with facial paralysis (like with Bell's Palsy or who have suffered a stroke), they are unable to purse the lips on the affected side and the suction is weak and liquid can dribble out. How does this relate to a baby? If a baby's tongue isn't working appropriately, they will often purse their lips to hold on tightly to the breast - this can result in the upper (and lower) lip turning in, even if there's no true lip tie.
Remember, most of the symptoms common to tied children are caused by the tongue's inability to move up: clicking, poor suction, poor breast drainage, leaking out the sides of the mouth, slipping to the end of the breast, popping on and off the breast, poor weight gain, falling asleep prematurely only to wake up hungry later, reflux/colic symptoms and pain/nipple trauma. The one major overlapping symptom set with isolated lip ties occurs in moms who have lots of pain and nipple damage without the other tongue symptoms. If the tongue has good superior movement in the mouth, then I will treat the upper lip alone and wait to determine if something else needs to be done.
If a practitioner focuses on a lip tie without evaluating the tongue or determines that the tongue is "normal" even in the presence of the aforementioned symptoms of tongue restriction, it may be an indication of inadequate education or experience in diagnosing or treating tongue ties. In my mind, the tongue should be the first place a practitioner should look before even worrying about the lip. Quite often, I will only treat the tongue if I'm not sure of the impact of the lip on the breastfeeding relationship. In those instances, I usually never see those babies back because the tongue release alone is sufficient to improve that relationship.