Effects of lingual strength training on lingual strength and articulator function in stroke patients with dysarthria

The role of oral and pharyngeal motor exercises in post-stroke recovery: A scoping review

OBJECTIVE

To analyze intervention goals, protocols, and outcome measures used for oral and pharyngeal motor exercises in post-stroke recovery.

DATA SOURCES

MEDLINE, EMBASE, CINAHL, PsychINFO, and Cochrane databases were searched in September 2022.

METHODS

Studies were included if they (1) recruited post-stroke adult patients, (2) administered exercises for the oral and/ or pharyngeal muscles, and (3) reported results at baseline and post-exercise. The extracted data included intervention goals, protocols, and outcomes. All outcomes were classified according to the International Classification of Functioning, Disability and Health (ICF).

RESULTS

A total of 26 studies were identified. Their intervention goals aimed to rehabilitate a broad spectrum of muscle groups within the oral cavity and pharynx and to improve the functions of swallowing, speech, facial expressions, or sleep breathing. Protocol duration ranged from 1 to 13 weeks, with various exercise repetitions (times per day) and frequency (days per week). Half of the studies reported using feedback to support the training, and these studies varied in the feedback strategy and technology tool. A total of 37 unique outcome measures were identified. Most measures represented the body functions and body structure component of the ICF, and several of these measures showed large treatment effects.

CONCLUSIONS

This review demonstrated inconsistency across published studies in intervention goals and exercise protocols. It has also identified current limitations and provided recommendations for the selection of outcome measures while advancing a multidisciplinary view of oral and pharyngeal exercises in post-stroke recovery across relevant functions.

Changes in ultrasonic vocalizations after unilateral cerebral ischemia in a rat stroke model

Stroke frequently results in communication impairments that negatively impact quality of life and overall recovery, yet the biological mechanisms underlying these changes are not well understood. Ultrasonic vocalizations (USVs) in rodent models of disease and aging have been used to improve our understanding of the biological mechanisms that underlie vocal deficits and their response to interventions. Changes in USVs after middle cerebral artery occlusion (MCAO) in mice have been reported, yet rat models have significant anatomical and behavioral advantages over mice, including the ability to vocally train rats with an established paradigm. We sought to determine whether a unilateral MCAO rat stroke model provides a biologically and behaviorally relevant way to study post stroke vocalization deficits. We hypothesized that left MCAO would be associated with changes in USVs. Six weeks after MCAO or sham-control surgery, USVs were recorded in rats using an established mating paradigm. Stroke was associated with differences in USV acoustics including more frequent use of simple calls characterized by shorter durations and restricted bandwidths. These parameters were also found to correlate with post stroke lingual weakness. This is the first study to describe changes to rat USVs using a stroke model. These results suggest the unilateral MCAO rat stroke model is a biologically and behaviorally relevant model to understand how stroke affects vocal behaviors.

Effects of tongue strengthening exercises on tongue muscle strength: a systematic review and meta-analysis of randomized controlled trials

Tongue strengthening exercise (TSE) has been proposed as an intervention to increase tongue strength and improve swallowing. However, clinical evidence of its effectiveness is lacking. In this review, seven databases were searched from inception to September 30, 2021 for randomized controlled trials that compared tongue strengths between the TSE intervention and control groups, obtained from maximal tongue elevation peak force in kilopascals (kPa). The Cochrane risk of bias tool was used for quality assessment. In total, 12 studies with 388 participants were included. The pooled meta-analysis demonstrated that the anterior tongue strength (ATS) (MD = 5.34 kPa; 95% CI 3.28–7.40; I² = 71%) and posterior tongue strength (MD = 8.12; 95% CI 3.45–12.79; I² = 90%) were significantly higher in the TSE intervention than that in the control group. Among healthy participants, subgroup analysis showed that TSE had improvements on ATS in all age groups, with the greatest improvement in old people (≥ 65 years) (MD = 8.01; 95% CI 4.39–11.64; I² = 30%). Meta-regression analysis revealed a nonsignificant trend toward greater improvement on tongue strength with increasing TSE duration. This study provides positive evidence that TSE may be beneficial in improving tongue strength and could be applied for adults, especially healthy older adults.

Relationships between maximum tongue pressure and second formant transition in speakers with different types of dysarthria

The effects of muscle weakness on speech are currently not fully known. We investigated the relationships between maximum tongue pressure and second formant transition in adults with different types of dysarthria. It focused on the slope in the second formant transition because it reflects the tongue velocity during articulation. Sixty-three Japanese speakers with dysarthria (median age, 68 years; interquartile range, 58–77 years; 44 men and 19 women) admitted to acute and convalescent hospitals were included. Thirty neurologically normal speakers aged 19–85 years (median age, 22 years; interquartile range, 21.0–23.8 years; 14 men and 16 women) were also included. The relationship between the maximum tongue pressure and speech function was evaluated using correlation analysis in the dysarthria group. Speech intelligibility, the oral diadochokinesis rate, and the second formant slope were based on the impaired speech index. More than half of the speakers had mild to moderate dysarthria. Speakers with dysarthria showed significantly lower maximum tongue pressure, speech intelligibility, oral diadochokinesis rate, and second formant slope than neurologically normal speakers. Only the second formant slope was significantly correlated with the maximum tongue pressure (r = 0.368, p = 0.003). The relationship between the second formant slope and maximum tongue pressure showed a similar correlation in the analysis of subgroups divided by sex. The oral diadochokinesis rate, which is related to the speed of articulation, is affected by voice on/off, mandibular opening/closing, and range of motion. In contrast, the second formant slope was less affected by these factors. These results suggest that the maximum isometric tongue strength is associated with tongue movement speed during articulation.

Effect of tongue-strengthening exercises on tongue strength and swallowing-related parameters in chronic radiation-associated dysphagia

BACKGROUND

Radiation-associated dysphagia (RAD) is highly prevalent in head and neck cancer (HNC) patients, with insufficient tongue strength (TS) as a characteristic of this disabling complication. The effects of tongue-strengthening exercises (TSE) on TS, swallowing, and quality of life (QoL) have not been studied in this population.

METHODS

A prospective phase 2 study using an 8 weeks during TSE protocol was carried out in 15 patients with chronic RAD. Outcome parameters were maximal isometric pressure (MIP), TS during swallowing (Pswal), swallowing function, and QoL. All parameters were evaluated at baseline, after 4 and 8 weeks of training, and 4 weeks after the last training session.

RESULTS

MIP increased significantly, without detraining effects. Pswal did not increase significantly, but relevant effect sizes were measured. Swallowing function ameliorated, but did not result in increased functional oral intake, self-reported outcome or QoL.

CONCLUSION

TSE in patients with RAD results in increased strength and swallowing function.