Experimental Injury Rodent Models for Oropharyngeal Dysphagia

Oropharyngeal dysphagia is a disorder that can make swallowing difficult and reduce the quality of life. Recently, the number of patients with swallowing difficulty has been increasing; however, no comprehensive treatment for such patients has been developed. Various experimental animal models that mimic oropharyngeal dysphagia have been developed to identify appropriate treatments. This review aims to summarize the experimentally induced oropharyngeal dysphagia rodent models that can be used to provide a pathological basis for dysphagia. The selected studies were classified into those reporting dysphagia rodent models showing lingual paralysis by hypoglossal nerve injury, facial muscle paralysis by facial nerve injury, laryngeal paralysis by laryngeal and vagus nerve injury, and tongue dysfunction by irradiation of the head and neck regions. The animals used in each injury model, the injury method that induced dysphagia, the screening method for dysphagia, and the results are summarized. The use of appropriate animal models of dysphagia may provide adequate answers to biological questions. This review can help in selecting a dysphagia animal system tailored for the purpose of providing a possible solution to overcome dysphagia.

Decreased Tongue Volume Post Radiation

Objectives: To evaluate volume changes within the tongue post chemoradiation therapy (CRT) Study Design: Retrospective review Setting: Academic Medical Center Subjects and Methods: Subjects included 19 patients that received CRT as the primary treatment for tonsillar or hypopharynx squamous cell carcinoma. Tongue volumes were calculated by three raters from thin slice computed tomography images collected before treatment and up to 29 months post-CRT. Body mass index (BMI) was also collected at each time point. Results: Inter-rater reliability was high with an ICC of 0.849 (95% CI = 0.773, 0.905). Linear mixed effects modeling showed a mean decrease of 0.45 cm3 (standard error of the mean [SEM] = 0.11) in tongue volume per month post-CRT ( P < .001). However, the addition of BMI to the model was significant (χ2 (4) = 25.0, P < .001), indicating that BMI was a strong predictor of tongue volume, with a mean decrease of 1.75 cm3 (SEM = 0.49) in tongue volume per unit decrease in BMI ( P < .001) and reducing the post-CRT effect on tongue volume decrease per month to 0.23 cm3 ( P = .02). BMI significantly ( P < .001) decreased by 0.11 units (SEM = 0.02) per month post radiation. Conclusion: Tongue dysfunction and decreased tongue strength are significant contributors to the dysphagia that patients experience after receiving CRT. In this study, both tongue volume and BMI decreased post-CRT; therefore, BMI could potentially be used as a predictor of tongue volume post-CRT.

Treatment of tongue dysfunction: rehabilitation for prescribers’ practice

Immature tongue function so-called “tongue-thrust or infantile and teeth apart swallow” and its rehabilitation involves multiple specialities in dentistry (pediatric dentistry, orthodontics, management of temporomandibular disorders, periodontics,…). Fifty years ago Mrs Fournier described a tongue rehabilitation technique. Given the difficulty to find a physiotherapist able to practice such a therapeutic, the aim of this article is to describe this therapeutic so that non-physiotherapists practitioners be able to initiate it and to teach it to their patients, at least for simple cases. It includes corrections of tongue immaturity, tongue resting position, deglutition and phonation. These changes might involve adaptive cortical neuroplasticity. Indeed these last years it has been shown in humans that standardised and calibrated tongue lift or protrusion exercises induce such plasticity in the tongue motor cortex.

Evaluation of a neuromotor ability of the tongue in patients at the developmental age using a stereognostic examination

Normal development of physiological functions affects normal maturation of the whole stomatognathic system and articulation. A persistent infantile swallowing pattern is listed as one of factors responsible for malocclusions and speech problems. “Stereognosis” originates from neurology and indicates an ability to recognise objects only by touch. <b>Aim</b>. The aim of the paper was to compare a neuromotor ability of the tongue in patients with a persistent infantile swallowing pattern compared to patients with a mature swallowing pattern. Material and methods. The study included 620 patients aged between 4 and 13 years. All subjects were diagnosed for swallowing dysfunctions with a spatula for speech therapy and a visual assessment when they were swallowing saliva, and then divided into 3 groups: study group (children with malocclusions and tongue dysfunctions) – 290 patients; comparator group (children with malocclusions and without tongue dysfunctions) – 240 patients; control group (children without malocclusions or tongue dysfunctions) – 90 patients. Stereognostic tests were performed according to Koczorowski methods and included recognition of geometrical shapes of silicone moulders using one’s tongue and without vision. <b>Results</b>. A differential analysis was performed and the following factors were included: age, sex and malocclusion. There were statistically significant differences between individual groups namely the study and comparator groups, study and control groups, and between the comparator and control groups. Results obtained indicate that a tongue dysfunction is a factor impairing sensory and motor correlation in patients at the developmental age. <b>Conclusions</b>. Patients with malocclusions complicated by tongue dysfunctions have impaired stereognostic sensation in the oral cavity. Impaired oral perception in patients at the developmental age with an abnormal position and functions of the tongue requires interdisciplinary specialist orthodontic treatment and speech therapy. <b>(Osiewacz S, Strzecki A, Szczepańska J, Pawłowska E. Evaluation of a neuromotor ability of the tongue in patients at the developmental age using a stereognostic examination. Orthod Forum 2017; 13: 267-82).</b>

The Effect of Tongue Exercise on Serotonergic Input to the Hypoglossal Nucleus in Young and Old Rats

Purpose Breathing and swallowing problems affect elderly people and may be related to age-associated tongue dysfunction. Hypoglossal motoneurons that innervate the tongue receive a robust, excitatory serotonergic (5HT) input and may be affected by aging. We used a rat model of aging and progressive resistance tongue exercise to determine whether age-related alterations in 5HT inputs to the hypoglossal nucleus can be modified. We hypothesized that tongue forces would increase with exercise, 5HT input to the tongue would decrease with age, and tongue exercise would augment 5HT input to the hypoglossal nucleus. Method Young (9–10 months), middle-aged (24–25 months), and old (32–33 months) male F344/BN rats received tongue exercise for 8 weeks. Immunoreactivity for 5HT was measured in digital images of sections through the hypoglossal nucleus using ImageJ software. Results Tongue exercise resulted in increased maximum tongue forces at all ages. There was a statistically significant increase in 5HT immunoreactivity in the hypoglossal nucleus in exercised, young rats but only in the caudal third of the nucleus and primarily in the ventral half. Conclusion Specificity found in serotonergic input following exercise may reflect the topographic organization of motoneurons in the hypoglossal nucleus and the tongue muscles engaged in the exercise paradigm.