The lingual frenulum is a fold of mucous membrane that helps stabilise the base of the tongue by binding the tongue to the floor of the mouth (5, 13, 14). Ankyloglossia occurs most frequently as an isolated anatomical variation in which the lingual frenulum is so short, hypertrophic or tight that it interferes with the free movement of the tongue (2, 5). The lingual frenulum may either be attached too close to the tip of the tongue and too far forward towards the inferior alveolar ridge, or it may be attached in a more posterior position on the tongue and the floor of the mouth, but be so short as to impede movement. When the tongue is lifted, the tip of the tongue may form a heart shape (2). Some classify ankyloglossia as a congenital malformation of the genioglossus muscles (15). The condition has been assigned its own ICD-10 code, Q38.1 Ankyloglossia (16).
The concept of 'posterior lingual frenulum' is controversial (4, 17, 18). Some maintain that the term describes the functional symptoms associated with tongue-tie, without necessarily requiring a visibly tight or short lingual frenulum (3, 18). According to the guidelines of the Norwegian Society of Pediatricians, 'posterior lingual frenulum' simply means a somewhat thicker submucosa in the posterior part of the lingual frenulum; the guidelines emphasise that there is only a single lingual frenulum (19). The term can also be misleading because the reasons for reduced tongue mobility may be complex, and not necessarily related to the lingual frenulum itself (17).
No specific embryological cause of ankyloglossia has been identified. It has been suggested that the short mucosa and increased fibromuscular tissue in the midline may result from insufficient development of the anterior tongue combined with incomplete apoptosis of the anteromedial lingual prominence and overfusion of the lateral lingual prominences (8, 20).
One of the functions of the tongue is to enable the infant to latch onto the mother's breast (21). Ultrasound examinations of breastfeeding infants suggest that good tongue mobility and the ability to create a vacuum are necessary for effective breastfeeding (22–25). An overly tight lingual frenulum may lead to difficulties by restricting the movement of the tongue (5, 13).
We believe a more cautious approach to surgical intervention is warranted than the trend we see today
The emphasis placed on symptoms of ankyloglossia differs depending on the age of the child (2, 3). The main issue in the neonatal period can be difficulty with breastfeeding, although the majority of children with tongue-tie do seem able to breastfeed normally (3). Several studies have examined the association between tongue-tie and breastfeeding problems, and typically describe poor latching, pain during breastfeeding, and sore nipples (5, 9, 26). These issues can in turn lead to impaired milk ejection, reduced milk production, clogged milk ducts and mastitis (8, 10, 21, 27). Tongue-tie alone does not appear able to fully explain these problems, but must be viewed in connection with other factors, including characteristics of the mother's breast (28).
Breastfeeding difficulties can manifest in various ways. Poor latching can lead to the infant losing its grip during breastfeeding. This may result in the child making 'clicking' sounds when the vacuum disappears, or in prolonged breastfeeding, irritability or poor weight gain (8, 10, 21). The extent to which ankyloglossia contributes to these symptoms is disputed, but they are included in several sets of ankyloglossia diagnostic criteria (Appendix 1). Tongue-tie does not appear to affect the ability to bottle-feed, probably because the infant uses a different technique to suck from a bottle than from the breast (3).