Introduction
Methods
Search Strategy
Eligibility Criteria
Study Selection
Risk of Bias (Quality) Assessment
Data Extraction Process
Results
Literature Retrieval
Quality Assessment
Study | Selection bias | Performance bias | Detection bias | Attrition bias | Reporting bias |
---|---|---|---|---|---|
Cho et al. [39] | + | + | + | ? | + |
Kim et al. [37] | − | + | + | − | + |
Park et al. [38] | − | + | + | + | + |
Robbins et al. [1] | + | + | + | − | − |
Robbins et al. [28] | + | + | + | − | − |
Steele et al. [2] | + | + | − | − | − |
Steele et al. [3] | − | + | − | + | − |
Study | Risk of bias | ||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Author | Year | Was the study question or objective clearly stated? | Were eligibility/selection criteria for the study population prespecified and clearly described? | Were the participants in the study representative of those who would be eligible for the test/service /intervention in the general or clinical population of interest? | Were all eligible participants that met the prespecified entry criteria enrolled? | Was the sample size sufficiently large to provide confidence in the findings? | Was the test/service/intervention clearly described and delivered consistently across the study population? | Were the outcome measures prespecified, clearly defined, valid, reliable, and assessed consistently across all study participants? | Were the people assessing the outcomes blinded to the participants' exposures/interventions? | Was the loss to follow-up after baseline 20% or less? Were those lost to follow-up accounted for in the analysis? | Did the statistical methods examine changes in outcome measures from before to after the intervention? Were statistical tests done that provided p values for the pre-to-post changes? | Were outcome measures of interest taken multiple times before the intervention and multiple times after the intervention (i.e., did they use an interrupted time-series design)? | Quality rating (good, fair, poor) |
Cho et al. [39] | 2017 | Yes | Yes | Yes | NR | No | No | CD | NR | CD | Yes | No | Poor |
Kim et al. [37] | 2017 | Yes | Yes | Yes | Yes | Yes | CD | CD | NR | Yes | Yes | No | Fair |
Park et al. [38] | 2015 | Yes | Yes | Yes | No | Yes | Yes | CD | NR | No | Yes | No | Poor |
Robbins et al. [1] | 2007 | Yes | Yes | Yes | Yes | No | CD | Yes | NR | Yes | Yes | No | Fair |
Robbins et al. [28] | 2005 | Yes | Yes | No | Yes | No | CD | Yes | NR | Yes | Yes | No | Poor |
Steele et al. [2] | 2013 | Yes | NR | Yes | Yes | No | Yes | No | Yes | Yes | Yes | No | Poor |
Steele et al. [3] | 2016 | Yes | Yes | Yes | Yes | Yes | Yes | CD | Yes | No | Yes | No | Good |
Patient Characteristics
Study | Year | N (M, F) | Average age in years (Range) | Control Group | Etiology |
---|---|---|---|---|---|
Cho et al. [39] | 2017 | 9 (NR) | NR | No | Stroke |
Kim et al. [37] | 2017 | 18 (11,7) | 62.17 (51.16–73.18) | N = 17 | Stroke |
Park et al. [38] | 2015 | 15 (6, 9) | 67.3 (56.7–77.9) | N = 14 | Stroke |
Robbins et al. [1] | 2007 | 10 (5, 5) | 69.7 (51–90) | No | Stroke |
Robbins et al. [28] | 2005 | 10 (4, 6) | NR (70–89) | No | Healthy |
Steele et al. [2] | 2013 | 6 (4, 2) | 42.33 (NR) | No | Acquired brain injury following motor vehicle accident |
Steele et al. [3] | 2016 | 5 (NR) | 71 (49–89) | Tongue pressure profile Training group; N = 6 | Stroke |
Question 1: Training Protocols
Study | Exercise | Device or tool | Repetition | Frequency (days/week) | Duration (weeks) | Guidance |
---|---|---|---|---|---|---|
Cho et al. [39] | Press tongue strongly against hard palate | None | 30 times | 5 | 4 | Education provided by OT on day 1 then supervised by caregiver |
Kim et al. [37] | TPRT | IOPI | 30 times | 5 | 4 | Two experienced OTs (no home practice) |
Park et al. [38] | Tongue muscle strength training (ant and post) | IOPI | 10 × 5 (total = 50 times) | 5 | 6 | Two experienced OTs (no home practice) |
Robbins et al. [1] | Isometric lingual exercise program (anterior and posterior) | IOPI | 10 × 3 each location (total = 60 times) | 3 | 8 | SLP contact by telephone or in person during the initial week then every 2 weeks thereafter |
Robbins et al. [28] | Isometric lingual exercise program (anterior) | IOPI | 30 × 3 (total = 90 times) | 3 | 8 | Contact with SLP at baseline, weeks 2, 4, and 6 paired with home practice (daily log) |
Steele et al. [2] | Maximum isometric tongue pressures (anterior and posterior) + amplitude accuracy | IOPI | 60 times | 2 | 11–12 | Direct supervision by a licensed SLP in clinic (no home practice) |
Steele et al. [3] | TPSAT –– TPPT | IOPI | 60 times | 2–3 | 8–12 | Direct supervision by a licensed SLP in clinic (no home practice) |
Question 2: Swallowing function
VFSS Protocols
Study | Thin | Thick | Puree | Semisolids | Solid | No. of trials | Frames (s) |
---|---|---|---|---|---|---|---|
Cho et al. [39] | NR | NR | NR | NR | NR | NR | NR |
Kim et al. [37] | NR | NR | NR | NR | NR | NR | NR |
Park et al. [38] | NR | NR | NR | NR | NR | NR | NR |
Robbins et al. [1] | Varibar thin liquid | No | No | Varibar pudding | No | Thin 3× (3 ml spoon, 10 ml catheter syringe); 2× (effortful 3 ml spoon) Semisolid: 3×: 3 ml spoon | NR |
Robbins et al. [28] | 3:1 (water:liquid Polibar plus) | No | No | Varibar pudding | No | Thin 3× (3 ml spoon, 10 ml catheter syringe); 2×: (effortful 3 ml spoon) Semisolid: 3×: 3 ml spoon | NR |
Steele et al. [2] | Thin solution of polibar and water (40% w/v) | No | EZ-HD barium powder with applesauce (40% w/v) | No | No | Thin 3×: 5 ml spoon Puree 3×: 5 ml spoon | NR |
Steele et al. [3] | Bracco EZ-Paque powder barium mixed with water (20% w/v) | Nectar: Bracco EZ-Paque powdered barium, xanthan gum thickener, mixed with water (20% w/v) | No | No | No | Thin 3× teaspoon amount Thick 3× teaspoon amount | NR |
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Thin teaspoon, 2.5 ml spoon, 3 ml spoon, 5 ml spoon, 10 ml catheter syringe, and consecutive swallow task (unreported volume);
-
Thick teaspoon;
-
Puree 5 ml spoon, 10 ml spoon, 15 ml spoon;
-
Semisolids ½ wafer dipped in barium, and 3 ml spoon.
Swallowing Biomechanics
Study | Inclusion criteria | Study design | Outcome measures collected |
---|---|---|---|
Cho et al. [39] | (1) Oropharyngeal dysphagia confirmed by VFSS; (2) No significant cognitive difficulties (MMSE > 24); (3) Ability to actively cooperate | Prospective Cohort Intervention Study | VDS (oral phase; pharyngeal phase) |
Kim et al. [37] | (1) Post-stroke oropharyngeal dysphagia confirmed by a VFSS; (2) Tongue muscle strength < 10 kPa; (3) MMSE score > 20; (4) Able to swallow voluntarily; (5) Cortex damage only; | Pre–post-treatment design | Tongue strength (anterior; posterior) Posterior tongue strength VDS (oral phase; pharyngeal phase) PAS |
Park et al. [38] | (1) Dysphagia from a stroke that was confirmed by a VFSS; (2) Onset duration > 6 months, (3) MMSE score ≥ 24 | RCT | VDS (oral phase; pharyngeal phase; total score) Tongue strength (anterior; posterior) |
Robbins et al. [1] | (1) 45 years of age or older; (2) Had a history of ischemic stroke; (3) Showed reduced lingual pressures with either the anterior or posterior tongue defined as < 40 kPa); (4) Physician referral for a VFSS that confirmed the presence of aspiration, penetration, or oropharyngeal residue | Prospective Cohort Intervention Study | PAS Durational measures (oral transit duration; oral clearance duration; pharyngeal transit duration; pharyngeal clearance duration; pharyngeal response duration; duration of hyoid maximum elevation; duration of hyoid maximum anterior excursion; duration to UES opening; duration of UES opening; total swallowing duration) Residue (oral cavity; vallecula; posterior pharyngeal wall; pyriform sinus; UES) Swallowing pressures Maximum isometric pressures (anterior and posterior) MRI (total lingual volume)/SWAL-QOL/Dietary intake questionnaire |
Robbins et al. [28] | (1) No history of swallowing problems or medical conditions that would affect oral motor performance, such as a history of acute or degenerative neurological condition or head/neck cancer | Prospective Cohort Intervention Study | PAS Durational measures (oral transit duration; stage transition duration; pharyngeal transit duration; pharyngeal response duration; duration of hyoid maximum elevation; duration to UES opening; duration of UES opening; total swallowing duration) Residue (oral cavity; vallecula; posterior pharyngeal wall; pyriform sinus; UES) Swallowing pressures Maximum isometric pressures(anterior and posterior) MRI (total lingual volume) |
Steele et al. [2] | (1) Dysphagia secondary to acquired brain injury following a motor vehicle accident; (2) Impaired swallowing safety, i.e., scores less than or equal to 3 on the PAS with thin liquids; (3) Post-swallow residues in the valleculae or pyriform sinuses with either thin and/or spoon-thick liquids measured using a 4-point ordinal scale | Case series | Isometric pressures (anterior; posterior) Saliva swallow pressures PAS Residue (vallecular; pyriform sinus) |
Steele et al. [3] | (1) History of recent stroke (4–20 weeks prior to enrollment); (2) One posterior maximum isometric pressure < 40 kPa; stage transition duration > 350 ms on at least one thin liquid barium swallow during intake VFSS; (3) Able to understand English; (4) Able to follow directions; (5) Able to tolerate oral trials under the supervision of a therapist | RCT | Posterior maximum isometric tongue-palate pressures Stage transition duration on thin liquid swallows PAS Residue (vallecular) |
Swallowing Safety
Swallowing Efficiency
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4 coded values on a nominal scalar mapped to scores on the VDS (0 = None; 4.5 = < 10%; 9 = 10–50%; and 13.5 = > 50%) [41].
Question 3: Other Measures
Question 4: Lingual Resistance Training Intervention Outcome
Tongue Pressure Generation
Swallowing Outcomes
Study | Measures | Results |
---|---|---|
Cho et al. [39] | VDS (oral phase; pharyngeal phase) | Significant improvement in oral phase components (p < 0.05) Significant improvement in the pharyngeal phase components (p < 0.05) |
Kim et al. [37] | Anterior tongue strength | Baseline MIP = 32.67 kPa; post-treatment MIP: 41.89 kPa Significant increases for both experimental and control; Statistically significant difference between groups (p < 0.000) |
Posterior tongue strength | Baseline MIP = 28.06 kPa; post-treatment MIP: 39.11 kPa Significant increases for both experimental and control; Statistically significant difference between groups (p < 0.000) | |
VDS (oral phase; pharyngeal phase) | Significant improvements in both oral and pharyngeal phase of VDS for experimental and control groups (p < 0.000), and also between groups (p < 0.000) | |
PAS | Significant decrease in PAS for both groups (p < 0.000); No significant differences between groups (p = 0.0471) | |
Park et al. [38] | VDS (oral phase; pharyngeal phase; total score) | Statistically significant differences in both the oral (p < 0.01) pharyngeal (p < 0.05) stages, and the total score (p < 0.01) for the experimental group. No significant difference in VDS scores between the experimental and control groups after the intervention |
Anterior tongue strength | Baseline MIP = 18.93 kPa; post-treatment MIP: 20.73 kPa Significant improvements for the anterior region pre–post-intervention for the experimental group (p < 0.01); no statistically significant difference between the two groups | |
Posterior tongue strength | Baseline MIP = 16.2 kPa; post-treatment MIP: 18.47 kPa Significant improvements for the posterior region pre–post-intervention for the experimental group (p < 0.01); no statistically significant difference in scores between the two groups | |
Robbins et al. [1] | PAS | Significantly reduced (increased safety) for the 3-ml thin liquid bolus condition at week 4 (p = 0.02) and week 8 (p = 0.005); 10-ml liquid bolus condition after at 8 weeks (week 4: p = 0.08; week 8: p = 0.003). A trend toward reduced airway invasion for the effortful swallowing condition was statistically significant after 4 weeks of exercise (week 4: p = 0.03, week 8: p = 0.07) |
Durational Measures (oral transit duration; oral clearance duration; pharyngeal transit duration; pharyngeal clearance duration; pharyngeal response duration; duration of hyoid maximum elevation; duration of hyoid maximum anterior excursion; duration to UES opening; duration of UES opening; total swallowing duration) | Significant decrease in the oral transit duration (time from beginning of posterior bolus movement until arrival of bolus head at ramus of mandible) for the 3-ml liquid bolus condition (p = 0.036) on 1 of 3 trials An increase in the pharyngeal response duration (time from beginning of hyoid excursion until hyoid returns to rest) for both the 3-ml liquid (p = 0.02) and the 10-ml liquid (p = 0.024) bolus conditions on 1 of 3 trials | |
Residue (oral cavity; posterior pharyngeal wall; pyriform sinus; UES) | Significant reduction in overall residue for the 3-ml effortful swallow (p = 0.02), 10-ml (p = 0 .02), and 3-ml (p = 0.01) bolus conditions, with the most significant changes in pharyngeal residue (p = 0.03) Reduction of average residue in the oral cavity (p = 0.07) and cricopharyngeus (p = 0.09) at week 8. No significant changes in average residue in the piriform sinuses (p = 0.17) or vallecula (p = 0.14) were observed after 8 weeks of exercise | |
Swallowing pressures | Significant increases on at least 1 of 3 trials for: 10 ml liquid (week 4 p = 0.04, week 8 p = 0.03), 3 ml liquid (week 4 p = 0.04, week 8 p = 0.004), Semisolid bolus conditions (week 4 p = 0.05, week 8 p = 0.02) | |
Maximum isometric pressures (anterior and posterior) | Anterior location: Baseline MIP = 35.6 kPa; Post-treatment MIP: 51.8 kPa Posterior location: Baseline MIP = 30.2 kPa; Post-treatment MIP: 54.6 kPa Statistically significant increase in anterior (week 4 p < 0.001, week 8 p < 0.001) and posterior tongue sites (week 4 p = 0.01, week 8 p < 0.001) | |
MRI (total lingual volume) | Increases lingual volume for two of three subjects (mean = 4.35%); A decline for one patient (6.5%) | |
SWAL-QOL | Statistically significant (fatigue, p = 0.047; communication, p = 0.026; and mental health p = 0.022) | |
Dietary intake questionnaire | Six subjects reported addition of difficult-to-swallow food items (nuts, popcorn, salad, and raw vegetables) to their diet | |
Robbins et al. [28] | PAS | No significant changes |
Durational Measures (oral transit duration; stage transition duration; pharyngeal transit duration; pharyngeal response duration; duration of hyoid maximum elevation; duration to UES opening; duration of UES opening; total swallowing duration) | No significant changes | |
Residue (oral cavity; posterior pharyngeal wall; pyriform sinus; UES) | No significant changes | |
Swallowing pressures | Significant based on bolus type (p = 0.47): 3 ml effortful swallow: statistically significantly increase (p = 0.001) 10 ml of thin liquid: statistically significantly increase (p = 0.04) 3 ml semisolid: statistically significantly increase (p = 0.01) 3 ml thin liquid: not significantly changed (p = 0.18) No significant changes in pressure rise rate overall or by bolus type | |
Maximum isometric pressures (anterior) | Baseline MIP = 41 kPa; Post-treatment MIP: 49 kPa A significant increase in peak isometric pressure (week 4, p = 0.002; week 6, p = 0.001) | |
MRI (total lingual volume) | Increased lingual volume (mean change = 5.1%) | |
Steele et al. [2] | Anterior isometric pressures | Increases (sustained above the Cohen’s d = 0.6 effect size boundary for at least three consecutive sessions) for participants 1, 2, 3, 4, 5 |
Posterior isometric pressures | Increases (beyond the d = 0.6 effect size boundary over at least three consecutive treatment sessions) for all six participants; sustained gains not seen for participant 1 | |
Saliva swallow pressures | Increases (beyond the effect size boundary over at least three consecutive sessions) for participants 1, 2, and 6, but gains were not clearly sustained for participants 2 and 6 Participants 3, 4, and 5 failed to demonstrate any notable changes in saliva swallowing pressures | |
PAS | Thin liquids: Improved swallowing safety (participants 1, 2, 4, 5, and 6); unchanged (participant 3) Spoon-thick liquids: post-treatment improvement of all those unsafe at baseline (participants 1, 2, 3, and 6); | |
Vallecular residue | Thin liquids: remained unchanged (three participants); worsened (three participants) Spoon-thick liquids: remained unchanged (two participants); worsened (4 participants) | |
Pyriform sinus residue | Thin liquids: improved (one participants); remained unchanged (2 participants) and worsened (3 participants) Spoon-thick liquids: improved (2 participants) remained unchanged (2 participants) and worsened (2 participants) | |
Steele et al. [3] | Maximum isometric pressures (posterior) | Pooled MIPs across groups: Baseline MIP = 21 kPa; Post-treatment MIP: 41 kPa Significant increases post-treatment for the entire to mean values of 41 kPa (p < 0.001; Cohen’s d = 1.15) An significant main effect of protocol (p = 0.08; Cohen’s d = 1.64): lower pressures for TPPT participants Significant protocol X age interaction (patients over 80 in the TPPT group had the lowest tongue pressures) No significant differences in the magnitude of change between treatment groups and no protocol X age-group interactions |
Stage transition duration | Thin liquids swallows: No statistically significant change (p = 0.13) | |
PAS | Thin & Nectar thickened liquids: There were no significant differences for either group, or across the entire pooled sample | |
Residue (vallecular) | Thin liquid: Statistically significant reduction in NRRSv scores (p = 0.05; Cohen’s d = 0.58). There were no significant differences between treatment groups Nectar-thick liquids: Non-significant reduction but medium effect size (Cohen’s d = 0.54) |