Dr Nikki Mill's pioneering studies on the functional anatomy of sucking and swallowing in breastfeeding

This is a photo of me and Nikki in the mountains outside Nelson, New Zealand, when I went to stay with her and her husband in August 2023. I had the most wonderful week. They cooked me fabulous food, and took me out into the mountains. Nikki is superfit, as you can tell. She once represented New Zealand as a rower at the Olympic Games. I'm ... let's say I'm ... not Olympic material; just trying to remain upright and catch my breath, with the help of that handy post.

Studies 1, 2	Study 3	Study 4	Study 5
Floor of mouth connective tissue dissection (adults and neonates)	Histology of frenulum and floor of mouth fascia	MRI of breastfeeding pairs with no problems N=12, < 5/12 of age	Flexible Endoscopic Evaluation of Swallowing (FEES) in breastfeeding babies with laryngomalacia: clinical and endoscopic changes with altered position (N=23 infants with noisy breathing and endoscopically confirmed laryngomalacia)
The lingual frenulum is not a discrete band of tissue	Highly variable elastin and collagen contents in floor of mouth fascia between individuals	Upper lip position is neutral during successful breastfeeding	Once infant's position is altered from supine or semi-lateral decubitus to semi-prone (consistent with the gestalt method), there is resolution of stridor and improved ability to latch
Variable appearance relates to variability in gliding and mobilization of mucosal and fascial layers. Elevation of tongue draws up either 1. Mucosa 2. Mucosa + fascia 3. Mucosa + fascia + muscle	Variability in thickness and number of elastin layers, that is, of type III collagen and elastin, which are distensible	Tongue-tip doesn't extend beyond alveolar ridge	Also there is more anterior positioning of the tongue base.
No anatomical basis to diagnosis of posterior tongue-tie - this term should be abandoned		No air visible in oral cavity when sucking or swallowing	There is decreased supraglottic tissue collapse.
No connection between base of tongue and floor of mouth fascia	No extension of floor of mouth fibres into septum of the tongue	Ultrasound is best modality for investigating dorsal tongue movement	There is decreased volume of milk into pyriform fossa with pauses.
No connection between hyoid bone and tongue or floor of mouth fascia		MRI is best modality for investigating swallowing	There is less penetration and aspiration of milk
No continuation of frenulum into median septum of tongue		Tongue and mandible move in synchrony
Risk of lingual nerve damage and sensory impairment with frenotomy, particularly laser		No gap between tongue base and soft palate. Soft palate elevation and pharyngeal constriction evident with swallow
		The seal, or mid-tongue elevation to palate at end of suck cycle appears impacted by height and contour of infant's hard palate as well as volume of maternal nipple and areolar tissue. Other anatomical variables are relevant when assessing causes of suck dysfunction

References

1. Mills N, Pransky SM, Geddes DT, Mirjalili SA. What is a tongue tie? Defining the anatomy of the in-situ lingual frenulum. Clinical Anatomy. 2019:doi:10.1002/ca.23343.

2. Mills N, Keough N, Geddes DT, Pransky S. Defining the anatomy of the neonatal lingual frenulum. Clinical Anatomy. 2019;32:824-835.

3. Mills N, Geddes DT, Amirapu S, Mirjalili SA. Understanding the lingual frenulum: histological structure, tissue composition, and implications for tongue tie surgery. International Journal of Otolaryngology. 2020(1820978.):doi: 10.1155/2020/1820978.

4. Mills N, Lydon A-M, Davies-Payne D, Keesing M, Mirjalili SA, Geddes DT. Imaging the breastfeeding swallow: pilot study utilizing real-time MRI. Laryngoscope Investigative Otolaryngology. 2020;5:572-579.

5. Mills N, Keesing M, Geddes DT, Mirjalili SA. Flexible endoscopic evaluation of swallowing in breastfeeding infants with laryngomalacia: observed clinical and endoscopic changes with alteration of infant positioning at the breast. Annals of Otology, Rhinology and Larygology. 2020:doi:10.117/00034894220965636.