A recent retrospective study
published in Journal of Rare Disorders: Diagnosis & Therapy
suggests a correlation between upper-lip ties and death from unexpected and unexplained asphyxia (UUA) in infants. The paper’s first author is Leslie Haller, DMD, of Miami-Dade Medical Examiner’s Department, Miami, FL.
Unexpected and unexplained asphyxia (UUA)
Though rare, UUA is the leading cause of death for infants between 1 and 12 months of age. The CDC estimates
about 1,500 infants died of UUA in 2014. “Sudden infant death syndrome” (SIDS) is another common term for the condition. These infant deaths cannot be explained by other medical problems or by accidental suffocation.
The cause of UUA is not completely understood. However, both internal and environmental factors seem to contribute to risk. For example, prematurity, exposure to cigarette smoke, and male sex increase the risk of UUA. Dr Haller and her colleague investigated whether upper lip-ties (frenums) might constitute another risk factor for sudden death in infants.
Lip and tongue-ties
Early in prenatal development, a layer of tissue connects the lips to the the jaw bones. During normal development, most of this tissue resorbs, allowing the lips to move freely. A lip-tie results when an unusual amount of tissue remains intact at birth. The lip-tie might or might not restrict full movement of the lips, depending on severity.
When a lip-tie is present, a tongue-tie is almost always present as well. This is a similar condition in which a layer of tissue remains between the base of the tongue and the floor of the mouth.
Infants with either type of tie tend may have difficulty breastfeeding, and they tend to regurgitate their stomach contents. Infants with these ties may have more difficulty modulating the opening between the lungs and GI tract, which may make UUA more likely to occur. Once the infant falls asleep, regurgitated stomach contents may be more likely to be inhaled, causing asphyxia.
Dr Haller and her colleague reviewed the autopsy photos of 327 infants who died of UUA between 2009 and 2015. They performed a blind evaluation of the photos for upper lip-ties, classifying the degree of apparent restriction.
The researchers found that 84% of the infants had had apparent restriction of the upper lip as evaluated by these photos. As a comparison, they estimated the incidence of upper lip-tie in the general population to be no more than 5% using previous reports. This strong association had a 99% confidence level analyzed on t-test.
It is unclear whether this association is causal or merely an association. For example, both UUA and lip-ties might result from some other factor, like low birth weight. It is also unclear whether this apparent risk derives from upper lip-ties themselves or only through their association with tongue-ties. Confirmation would require a prospective matched case-control study.
Frenectomies as UUA prevention?
In light of these results, medical professional may need to include evaluation of upper-lip frenums as part of their standard medical exam, especially for infants who have other risk factors for UUA. Unlike tongue-ties, which are sometimes difficult to diagnose, health professionals can assess lip-ties relatively easily. Currently, many infants with lip-ties and tongue-ties often do not receive frenectomies
, surgical treatment to remove the large frenums.
If lip-ties and tongue-ties do truly represent a major increased risk factor for UUA, it may be worth considering performing frenectomies more frequently. The authors argue, “With current research showing the safety, effectiveness, and simplicity of laser assisted frenectomies even in infants only a few days old, and with the majority of UUA deaths occurring within the first few months of life, pediatricians should consider the possibility that treating restricted frenums within the first few months of life would be prudent.”