Mirjalili, S. AliGeddes, Donna TMills, Nicola A (Nikki)2020-09-142020-09-142020http://hdl.handle.net/2292/52826Aims Breast milk is the ideal nutrition for a human infant, but the physical process of breastfeeding is not always straightforward. When problems occur, an understanding of functional anatomy is crucial to determine when anatomical factors may be impacting on breastfeeding and how to best manage these issues. There is a growing interest in the lingual frenulum’s potential role in causing breastfeeding difficulties, with increasing diagnosis of ankyloglossia and rising frenotomy rates in infants. The first aim of this study was to define lingual frenulum anatomy, in the context of the absence of a comprehensive description of frenulum structure and an ambiguous relationship between frenulum structure and functional limitation of tongue movement during breastfeeding. Other potential causes for difficulty breastfeeding include airway compromise and difficulty regulating breathing with rapid changes in maternal milk flow. Understanding these problems is challenged by difficulties imaging the breastfeeding swallow and a limited understanding of the 3-dimensional events occurring during swallowing. Assessment of breastfed infants with compromised swallowing commonly involves imaging using bottle feeding, with any recommended modifications to feeding often excluding the possibility of continued breastfeeding. Therefore secondly, we aimed to explore modalities for imaging or viewing the breastfeeding swallow to progress our understanding of normal swallowing function during breastfeeding. We also aimed to determine the impact of gravity on airway compromise and aspiration risk during breastfeeding, with the hypothesis that latching position may be modified therapeutically to minimise aspiration risk and improve the possibility of successful breastfeeding. Methods To determine the structure of the lingual frenulum, fresh tissue microdissection of the lingual frenulum and FOM was performed on nine adult and four premature infant cadavers, with photo-documentation and description of findings. In addition, histological assessment of frenulum structure and tissue composition was then performed on 10 en-bloc anterior tongue, FOM and lingual frenulum embalmed specimens, with frenulums from an additional 3 fresh tissue specimens harvested with the tongue frozen in an elevated position. All 13 specimens were prepared as ten-micron coronal sections, using a variety of stains to determine the general morphology of the frenulum, its relationship to neighbouring structures, the presence of elastin fibres and collagen typing. With respect to swallowing, in a prospective observational study, we used real-time MRI to image breastfeeding in 12 normal infants. We then reviewed 48 flexible endoscopic evaluation of swallowing (FEES) performed on breastfeeding infants referred for noisy breathing, difficulty feeding and/or concerns regarding possible aspiration. From this audit we provide a description of the dynamic anatomy and variability of the breastfeeding swallow as viewed during FEES and the endoscopically observable changes to airway and/or swallowing occurring following modification of infant positioning. Results The lingual frenulum is a dynamic structure, formed by tongue elevation raising a midsagittal fold in a layer of fascia that spans across the FOM, inserting immediately beneath the mucosa to the inner surface of the mandible. The fascial thickness, composition and extent the fascia mobilises into the fold of the frenulum with tongue elevation varies on a spectrum, providing a structural explanation for individual variability in lingual frenulum morphology. Lingual nerve branches are located superficially on the ventral tongue and are therefore vulnerable to injury during frenotomy. Static and dynamic images of the breastfeeding swallow were successfully captured using real-time MRI, enabling viewing of mandibular movement with sucking, palatal elevation and pharyngeal constriction with swallowing, diaphragm movement with breathing and milk entering the stomach. Breast milk was clearly visualised, being high intensity on T2 sequences. Some technical challenges were encountered, mainly associated with difficulties acquiring and maintaining a midsagittal orientation due to infant movement during feeding. Similarity in tissue densities of the lips, tongue, nipple and hard palate limited definition between the interface of these structures. Endoscopic observation of the breastfeeding swallow identified that modification of latching position improved dynamic airway compromise in 94% of infants that warranted this intervention. Infants with laryngomalacia improved when breastfed in a semi-prone position. Silent aspiration in infants with unilateral vocal fold paralysis resolved when positioned side-lying with the affected vocal fold superior. Conclusion The lingual frenulum is not a discrete midline structure, challenging the longstanding belief of lingual frenulum structure being a midline, submucosal “band”. We have provided an anatomical construct for understanding and describing variability in lingual frenulum morphology, laying the foundation for future research to assess the impact of variables in frenulum morphology on tongue mobility. Real-time MRI imaging has successfully captured dynamic images of the breastfeeding swallow but technical and practical challenges make it currently unsuitable for use in clinical practice. FEES has provided an understanding of the impact of an infant’s breastfeeding position on airway and on fluid dynamics during swallowing. This creates the opportunity to therapeutically modify an infant’s positioning during breastfeeding to optimise their airway, reduce aspiration risk and maximise the possibility of safe and successful breastfeeding.Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated.Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated.https://researchspace.auckland.ac.nz/docs/uoa-docs/rights.htmhttp://creativecommons.org/licenses/by-nc-sa/3.0/nz/Thesis2020-07-22Copyright: The authorhttp://purl.org/eprint/accessRights/OpenAccessQ112953090