How Passive Neck Immobilisation Influences Tongue Mobility and Strength: An Observational Study

Abstract

Background: There is a physiological association of the neck movements and jaw and tongue movements. However, there are no previous data regarding the performance of the tongue when the neck is under a lack of movement condition.

Objective: To quantify the tongue's maximal strength and mobility under an experimental restriction of cervical mobility.

Methods: This cross-sectional study recruited 33 healthy volunteers. We measured the tongue's mobility and maximal strength reached at the posterior, middle and anterior parts of the tongue; all were performed with and without neck immobilisation. A neck collar was used for the experimental restriction of cervical mobility.

Results: ANOVA revealed no differences in tongue strength between cervical condition (p = 0.84), but differences were found among the three tongue areas' strength (p < 0.001), according to the post hoc results the posterior area of the tongue resulted significantly weaker compared to the anterior (with collar p = 0.006; without collar p = 0.01) and midparts (with collar p = 0.03; without collar p = 0.006). Significant differences were also found in the tongue's range of motion (ROM) between groups for the protraction (p = 0.02). A subclassification of the participants was made according to the greatest strength obtained with (CCI group) or without (WCI group) neck collar, or no difference (NC group). The analysis of variance showed significant changes in tongue strength between groups at the tongue's anterior area (F = 5.28; p = 0.01), middle area (F = 9.83; p < 0.001) and posterior area (F = 4.05; p = 0.02). The post hoc analyses showed strength in the middle area of the tongue changed between neck conditions, obtaining significantly greater results without the neck collar compared with those with the neck collar (p = 0.01; d = 1.10).

Conclusion: The results of this study indicate a trend suggesting that posture induced by experimental cervical fixation may influence tongue strength, with a possible greater effect in the middle area of the tongue compared to the anterior and posterior areas; however, it affects tongue range of motion. These findings suggest that cervical posture could be an important factor to consider in clinical assessments and interventions involving tongue function. Nonetheless, a larger sample size and further studies are needed to draw more definitive conclusions and understand these potential associations.

Keywords: immobilisation; movement; muscle strength; neck; posture; tongue.

FIGURE 1

IOPI device and neck collar. Procedure for the measurements with and without the neck collar, inserting the IOPI's probe in the mouth to place it onto the corresponding part of the tongue (anterior, middle or posterior).

FIGURE 2

Measurement of the tongue's range of movement. Protrusion and lateral movement.

FIGURE 3

Graph representing the percentage of participants who achieved greater tongue strength at each tongue area when measured with (blue/light grey) or without (dark grey) neck fixation by the neck collar. Also shown is the percentage of participants who demonstrated no strength change between both neck conditions (medium grey/red).

FIGURE 4

Influence of the cervical fixation. Comparisons of tongue strength in the various tongue areas performed with or without neck immobilisation. The largest differences were found for the middle part of the tongue; neck immobilisation was associated with lower strength compared with the strength achieved without immobilisation. *p < 0.05; **p < 0.001.