Tongue Rehabilitation Device for Dysphagic Patients

Abstract

Dysphagia refers to difficulty in swallowing often associated with syndromic disorders. In dysphagic patients' rehabilitation, tongue motility is usually treated and monitored via simple exercises, in which the tongue is pushed against a depressor held by the speech therapist in different directions. In this study, we developed and tested a simple pressure/force sensor device, named "Tonic Tongue (ToTo)", intended to support training and monitoring tasks for the rehabilitation of tongue musculature. It consists of a metallic frame holding a ball bearing support equipped with a sterile disposable depressor, whose angular displacements are counterbalanced by extensional springs. The conversion from angular displacement to force is managed using a simple mechanical model of ToTo operation. Since the force exerted by the tongue in various directions can be estimated, quantitative assessment of the outcome of a given training program is possible. A first prototype of ToTo was tested on 26 healthy adults, who were trained for one month. After the treatment, we observed a statistically significant improvement with a force up to 2.2 N (median value) in all tested directions of pushing, except in the downward direction, in which the improvement was slightly higher than 5 N (median value). ToTo promises to be an innovative and reliable device that can be used for the rehabilitation of dysphagic patients. Moreover, since it is a self-standing device, it could be used as a point-of-care solution for in-home rehabilitation management of dysphasia.

Keywords: dysphagia; personalized medicine; rehabilitation; tongue.

Figure 1

Traditional exercises proposed by speech therapists to treat and monitor tongue mobility rehabilitation. A speech therapist holds a disposable depressor against which dysphagic patients exert pressure with the tongue. Based on the directionality, we distinguish the exercises as (a) forward; (b) lateral (right/left); and (c) vertical (up/down) tasks.

Figure 2

Architecture of ToTo device. (a) The axonometric view of ToTo presents the main components: (1) frame; (2) traction spring; (3) graduated scale; (4) disposable tongue depressor; (5) depressor holder with rollers supported by ball bearings. (b) A picture of the ToTo prototype implemented with two traction springs (one per side).

Figure 3

(a) Forward exercise performed by a volunteer. (b) Mechanical scheme of the forward thrust with depiction of the pushing force $F_L$ exerted by the tongue and the reaction force $F_m$ from the linear spring.

Figure 4

Experimental protocol to assess ToTo performance: (a) forward, (b) vertical (up and down), and (c) lateral (right and left) thrust exercises.

Figure 5

Histograms depicting the related-samples differences for each loading direction: (a) forward; (b) right; (c) left; (d) up; (e) down; and (f) omni-directional. We observe similarities among panels a–d and f with distributions having peaks between 2–3 N. Panel (e) presents, in contrast, a broader distribution of counts, with occurrences up to ~12 N, showing higher tongue musculature improvement.