Author: Jennifer Triandafilou, M.A., CCC-SLP  |  Simon Says Speech
ASHA CEUs: 0.05 (30 minutes / Intermediate)  |  Content Area: Orofacial Myofunctional Disorders
Completion Requirement: Read this article in full and pass the post-reading quiz with 80% or higher. Complete the program evaluation.

Learning Outcomes
Upon completing this article and the post-reading assessment, the learner will be able to:
Distinguish between structural ankyloglossia and the functional ankyloglossia framework introduced by Zaghi and colleagues.
Describe the Tongue Range of Motion Ratio (TRMR) and Tongue Range of Motion Ratio — Lingual Palatal Suction (TRMR-LPS) as clinical assessment tools.
Identify the downstream functional consequences of restricted tongue mobility across speech, swallowing, breathing, and craniofacial development.
Articulate the SLP's role within the interdisciplinary frenuloplasty team, including pre- and post-surgical myofunctional therapy.
Apply at least two clinical decision-making principles from this framework to their caseload.

Introduction: A Field in Transition
For most of its history, ankyloglossia — commonly known as tongue-tie — was evaluated almost entirely by what a clinician could see: the visible length and insertion of the lingual frenulum. If the frenulum looked short or appeared to tether the tongue tip, a referral for frenotomy might follow. If it looked normal, the case was often closed. The problem with this approach is that the frenulum's visual appearance tells only part of the story.
Over the past decade, a growing body of research — much of it led or co-authored by otolaryngologist Dr. Soroush Zaghi and his colleagues at the Breathe Institute in Los Angeles — has shifted the field toward a functional model. In this framework, the more important clinical question is not what the frenulum looks like, but what the tongue can do. Can it elevate fully? Can it create and sustain suction against the palate? Does restricted mobility affect how the patient breathes, swallows, sleeps, or speaks — and how is it shaping their craniofacial development over time?
This article explores the core concepts in Zaghi's functional ankyloglossia framework, examines the assessment tools that have emerged from this research, reviews the clinical consequences of unrecognized posterior tongue restriction, and considers what all of this means for the speech-language pathologist working in myofunctional therapy or with tongue-tie populations.
Why This Matters to SLPs: Speech-language pathologists are uniquely positioned to identify functional tongue restriction — and to provide the pre- and post-surgical myofunctional therapy that makes frenuloplasty outcomes durable. Understanding this framework is no longer optional for SLPs working in OMT.

Part 1: From Structural to Functional — Rethinking Ankyloglossia
The Limits of Structure-Based Diagnosis
Traditional approaches to tongue-tie diagnosis have relied primarily on structural classification systems. The Kotlow classification grades the frenulum based on the free length of the tongue anterior to the frenulum attachment. The Hazelbaker Assessment Tool for Lingual Frenulum Function (ATLFF), developed for neonates, combines both functional and structural components. The Coryllos classification describes the frenulum's insertion site and tissue type.
Each of these tools has clinical utility, particularly for infant populations where breastfeeding difficulties often prompt early assessment. However, they share a common limitation: they measure the frenulum itself, not the functional capacity of the tongue as a whole. This distinction becomes especially significant when evaluating school-age children and adults, where the consequences of tongue restriction often manifest not as visible tethering of the tongue tip, but as restricted posterior tongue mobility — a phenomenon that is easy to miss with structure-based evaluation alone.
Introducing Functional Ankyloglossia
In a landmark 2017 study published in Sleep and Breathing, Yoon, Zaghi, and colleagues proposed a functional definition of ankyloglossia and introduced the Tongue Range of Motion Ratio (TRMR) as a standardized assessment metric. In a validation sample of over 1,000 subjects, they examined the relationship between frenulum length, TRMR scores, and tongue mobility, establishing graded cutoffs that could be used to identify functional restriction regardless of the frenulum's visual appearance.
The TRMR measures the ratio of vertical tongue extension — specifically, elevation of the tongue tip to the incisive papilla (TIP) — to maximum interincisal opening (MIO). The calculation is straightforward:
TRMR = (TIP elevation ÷ Maximum Interincisal Opening) × 100
A TRMR of 80% or above is considered normal. Scores of 50–79% indicate mild-to-moderate restriction; scores below 50% suggest severe restriction. This ratio-based approach is significant because it accounts for variation in mouth opening size, making it applicable across age groups and facial morphologies.
The Posterior Tongue Problem
Even as the TRMR gained clinical traction, Zaghi and colleagues recognized that it was measuring only the anterior portion of tongue mobility — the tongue tip's ability to elevate. Many patients with functional complaints — difficulty with swallowing, low tongue posture, sleep-disordered breathing, or dental malocclusion — presented with apparently normal TRMR scores but demonstrated restricted posterior tongue mobility when examined more carefully.
This observation drove the development of a complementary measure: the Tongue Range of Motion Ratio – Lingual Palatal Suction (TRMR-LPS). Published in the Journal of Oral Rehabilitation in 2021, this study by Zaghi and colleagues validated the TRMR-LPS as a functional metric for posterior tongue mobility. To perform this assessment, the clinician asks the patient to lift the tongue body into suction against the palate — what many OMT practitioners call a 'suction hold' — and measures the ratio of this elevated position to maximum interincisal opening.
The clinical significance of the TRMR-LPS cannot be overstated. A patient may demonstrate full anterior tongue elevation (normal TRMR-TIP) yet be unable to sustain palatal suction or exhibit dramatically reduced posterior elevation (abnormal TRMR-LPS). This is precisely the profile of the 'posterior tongue-tie' patient: the frenulum appears normal or borderline on visual inspection, the tongue tip can elevate to the incisive papilla, yet the tongue body cannot rise fully against the palate — and this restriction has cascading consequences for tongue posture, nasal breathing, swallowing mechanics, and craniofacial development.
Recent Refinement: The Floor-of-Mouth Hold Maneuver
More recent work from Zaghi's group has refined the TRMR-LPS assessment further, addressing a subtle but important confound: patients can sometimes achieve an apparent suction hold by elevating the entire floor of the mouth, rather than by truly lifting the tongue body with intrinsic lingual muscle effort. To isolate genuine tongue movement from this compensation, clinicians now incorporate a floor-of-mouth hold maneuver during the exam. Using a gloved finger, the examiner applies gentle, stabilizing pressure at the sublingual caruncles, near the mandibular alveolar ridge, holding the floor of the mouth in place while the patient attempts the suction hold. With the floor of the mouth stabilized, any depression, dimpling, or cupping at the dorsal mid-tongue, along with palpable tension, becomes a much clearer signal of true intrinsic restriction, rather than a false pass produced by jaw, neck, or floor-of-mouth compensation. This refinement matters clinically because it reduces the risk of under-diagnosing posterior tongue-tie in patients who have unconsciously learned to compensate for years. For the SLP, it reinforces a broader theme in this evolving research: functional assessment tools continue to be refined specifically to separate true tongue mobility from the compensatory patterns patients develop to work around a restriction.
Clinical Takeaway: When evaluating a patient for tongue-tie, always assess both anterior (TRMR-TIP) and posterior (TRMR-LPS) mobility, and consider stabilizing the floor of the mouth during the suction hold to rule out compensation. A structurally 'normal' frenulum does not rule out functionally significant posterior restriction.

Part 2: Downstream Consequences of Restricted Tongue Mobility
Craniofacial Development
The tongue is the primary internal scaffold for palatal development. When a child's tongue rests habitually at the floor of the mouth rather than against the palate — as is typical in functional ankyloglossia — the transverse and sagittal growth of the maxilla is deprived of the internal pressure that drives normal arch development. The result is a narrower, higher-vaulted palate, increased dental crowding, and an elongated soft palate.
Zaghi and colleagues documented these relationships in a 2017 morphological study, finding that restricted tongue mobility was significantly associated with maxillary hypoplasia and soft palate elongation. The elongated soft palate, in turn, contributes to pharyngeal obstruction during sleep — connecting tongue-tie to pediatric sleep-disordered breathing in a way that is now well-supported in the literature.
Sleep-Disordered Breathing
The relationship between ankyloglossia and obstructive sleep apnea has become one of the most clinically important areas in this field. When the tongue cannot maintain a resting position against the palate, it tends to fall posteriorly during sleep, reducing the posterior airway space. This is compounded by the narrowed maxillary arch and elongated soft palate described above.
Research from Zaghi's group and from Guilleminault's lab at Stanford has shown that a short lingual frenulum is a risk factor for pediatric sleep-disordered breathing — and that treatment of the underlying tongue restriction through frenuloplasty combined with myofunctional therapy can produce meaningful improvements in airway outcomes. Critically, these improvements are more durable when myofunctional therapy addresses tongue posture, nasal breathing, and lip seal as part of a comprehensive protocol — not when frenuloplasty is performed in isolation.
Swallowing and Feeding
Restricted tongue mobility affects the full swallowing sequence. In infants, it is most visible in breastfeeding difficulties — poor latch, inefficient milk transfer, nipple pain, and early feeding fatigue. In older children and adults, the effects are more subtle but no less significant: compensatory swallowing patterns involving excessive jaw, lip, and buccinator activity; food residue in the oral cavity post-swallow; and reduced bolus formation and control.
SLPs assessing swallowing in patients with suspected OMDs should consider tongue-tie as a potential underlying factor — particularly in patients with a history of infant feeding difficulty, current atypical swallow patterns, or who have not achieved expected gains from swallowing therapy alone.
Speech Production
The relationship between ankyloglossia and speech is frequently debated in the literature, with some earlier studies suggesting minimal impact on speech intelligibility. However, these studies often used structure-based definitions of tongue-tie and focused primarily on articulation. When speech is evaluated through a functional lens — including tongue endurance, precision on high-load tasks, speaking fatigue, and the quality of lingual-alveolar and lingual-palatal sounds — a different picture emerges.
Patients with posterior tongue restriction may produce compensatory articulation patterns that are intelligible but effortful. Sounds requiring sustained tongue-to-palate contact — particularly /l/, /n/, /t/, /d/, and retroflex /r/ — may be produced with compensatory strategies that become apparent only on extended speech tasks or in connected speech at conversational rate. Voice professionals — singers, actors, public speakers — are an emerging population for whom posterior tongue restriction and associated myofascial tension are increasingly being recognized as contributors to vocal fatigue, tension, and reduced resonance.
Clinical Observation: If a patient has completed articulation therapy without achieving expected carryover — especially for lingual sounds — consider a functional tongue-tie evaluation as part of the differential. The 'treatment-resistant' articulation client may have an underlying structural reason for their compensatory patterns.

Part 3: The SLP's Role in Interdisciplinary Care
Pre-Surgical Myofunctional Therapy
One of the most significant paradigm shifts in the tongue-tie field is the growing consensus that frenuloplasty alone — without myofunctional therapy — produces limited and often temporary results. The reason is straightforward: the patient with functional ankyloglossia has spent months or years developing compensatory neuromuscular patterns. The frenulum release removes the structural restriction, but it does not automatically reprogram the tongue's habitual posture or movement patterns. Without active neuromuscular retraining, compensatory patterns persist, scar tissue can form, and the patient may not achieve the functional improvements that motivated surgery.
Pre-surgical myofunctional therapy serves two important functions. First, it begins the process of neuromuscular awareness and retraining — helping the patient develop the tongue elevation, range of motion, and suction patterns that post-surgical exercises will build on. Second, it establishes a documented functional baseline: the clinician measures and records TRMR-TIP and TRMR-LPS, photographs lingual range of motion, and notes functional complaints. This baseline makes post-surgical progress measurable and meaningful.
Post-Surgical Myofunctional Therapy
In Zaghi's published protocols, post-surgical myofunctional therapy begins immediately after frenuloplasty — typically within 24 to 48 hours — with gentle stretching and mobilization exercises to prevent scar tissue contracture. This early phase is critical: the window for optimal wound healing and tissue remodeling is narrow, and passive wound dilation without active functional exercise is insufficient to achieve lasting range of motion gains.
In a 2019 study in Laryngoscope Investigative Otolaryngology, Zaghi and colleagues reported outcomes in 348 patients who underwent lingual frenuloplasty with structured myofunctional therapy. The majority of patients reported improvements across multiple functional domains — tongue mobility, sleep, breathing, swallowing, and speech — with a high overall satisfaction rate. Importantly, patients who completed the full myofunctional therapy protocol reported better outcomes than those who did not.
For the SLP, this means that post-surgical myofunctional therapy is not a gentle adjunct — it is a clinical necessity. Protocols should include: wound dilation and scar management exercises in the first two to four weeks; progressive tongue elevation and range of motion exercises; suction hold training targeting TRMR-LPS improvement; and integration of newly available tongue mobility into functional speech and swallowing tasks.
Interdisciplinary Communication
Effective care for patients with functional ankyloglossia requires fluent communication between the SLP, the releasing provider (typically an ENT, oral surgeon, or dentist), and often an orthodontist or pediatric dentist. The SLP's documentation contributes functional data that surgical providers cannot easily gather themselves — TRMR measurements, functional descriptions of swallowing and speech, and a clear narrative of how tongue restriction is affecting the patient's daily life.
When referring to a releasing provider, SLPs should include: TRMR-TIP and TRMR-LPS measurements, a description of functional limitations, a summary of myofunctional therapy to date, and specific functional goals that surgery is intended to support. This documentation positions the SLP as a knowledgeable clinical partner and supports shared decision-making with the family and the surgical team.


Conclusion
Zaghi's functional ankyloglossia framework represents a meaningful advance for SLPs working in myofunctional therapy and with tongue-tie populations. By shifting evaluation from the frenulum's structure to the tongue's functional capacity — and by providing validated, reproducible assessment tools in the TRMR-TIP and TRMR-LPS — this body of work gives clinicians a more complete picture of who is affected, how significantly, and what treatment needs to address.
For SLPs, the practical implications are clear. Incorporate both anterior and posterior tongue mobility measures into your evaluation protocol. Consider functional tongue restriction as a differential factor in treatment-resistant articulation, persistent atypical swallow, and sleep-related concerns. Provide structured pre- and post-surgical myofunctional therapy as a clinical standard, not an optional add-on. Document functional outcomes with the same rigor as surgical providers document structural ones.
As the evidence base continues to grow and interdisciplinary care models mature, the SLP's role in this space will only expand. The field does not need more procedures performed in isolation — it needs clinicians who understand the full functional picture and can support lasting change.


References
Yoon, A., Zaghi, S., Weitzman, R., Ha, S., Law, C.S., Guilleminault, C., & Liu, S.Y. (2017). Toward a functional definition of ankyloglossia: Validating current grading scales for lingual frenulum length and tongue mobility in 1052 subjects. Sleep and Breathing, 21, 767–775.
Zaghi, S., Shamtoob, S., Peterson, C., Christianson, L., Valcu-Pinkerton, S., Peeran, Z., … & Yoon, A.J. (2021). Assessment of posterior tongue mobility using lingual-palatal suction: Progress towards a functional definition of ankyloglossia. Journal of Oral Rehabilitation, 48, 692–700.
Zaghi, S., Valcu-Pinkerton, S., Jabara, M., Norouz-Knutsen, L., Govardhan, C., Moeller, J., … & Camacho, M. (2019). Lingual frenuloplasty with myofunctional therapy: Exploring safety and efficacy in 348 cases. Laryngoscope Investigative Otolaryngology, 4, 489–496.
Yoon, A.J., Zaghi, S., Ha, S., Law, C.S., Guilleminault, C., & Liu, S.Y. (2017). Ankyloglossia as a risk factor for maxillary hypoplasia and soft palate elongation: A functional-morphological study. Orthodontics and Craniofacial Research, 20, 237–244.
Guilleminault, C., Huseni, S., & Lo, L. (2016). A frequent phenotype for paediatric sleep apnoea: Short lingual frenulum. ERJ Open Research, 2(3), 1–8.
Shortland, H.L., Hewat, S., et al. (2021). Orofacial myofunctional therapy and myofunctional devices used in speech pathology treatment: A systematic quantitative review of the literature. American Journal of Speech-Language Pathology.
American Speech-Language-Hearing Association. (2019). Orofacial myofunctional disorders. ASHA Practice Portal. Retrieved from www.asha.org


Disclosure Statement
The author has no financial conflicts of interest to disclose in relation to this article. ASHA CE Provider approval does not imply endorsement of course content, specific products, or clinical procedures.