Between July 2022 and April 2023, a total of 18 patients with dysphagia due to NPCR were recruited from the rehabilitation department of the third affiliated hospital of Sun Yat-sen University. Table 1 presents the demographic information of all patients. Within the patients' cohort, there were 14 males and 4 females, with an average age of 53.78 ± 11.38 years (ranging from 38 to 79 years). On average, the patients had undergone radiotherapy treatment 10.56 years ago (ranging from 5 to 25 years), and their duration of dysphagia was approximately 2.39 years (ranging from 1 to 4 years). The number of radiotherapy sessions received by the patients ranged from 32 to 34.
Table 1
Demographic information of NPC patients
Variables | Gender(m%) | Age(y) | Radiotherapy sessions (n) | Time to last radiotherapy session (y) | Dysphagia onset (y) |
NPC Patients (n = 18) | 77.78% | 53.78 ± 11.38 | 34.22 ± 0.42 | 10.56 ± 4.45 | 2.39 ± 0.68 |
Abbreviation:NPC, Nasopharyngeal carcinoma; m, male; y,year; n,number |
Table 2
The Intervention Protocol
Region | Objective | Intervention | Duration of maintenance | Frequency/day | Total frequency |
TAR | To increase TAR flexibility | 1.TAR flexibility training:Patients were instructed to touch their teeth with TAR as much as possible, including the medial and lateral parts of the upper alveolar and the medial and lateral parts of the lower alveolar bone. | 10s | 10 times per session,2 sessions a day | 10 days per cycle |
To increase TAR flexibility | 2.TAR active movement training:patients try their best to use TAR to lick lips, including up, down, left and right four directions.The patient complete 10 repetitions of elevation (up), 10 repetitions of depression (down), 10 repetitions of lateralization to the right (right) and 10 repetitions of lateralization to the left (left). |
To increases the forward and upward force of the tongue | 3.TAR suction cotton swab training:which involved putting a cotton swab into TAR and using it to suck the cotton swab. |
TCR | To increase the muscle strength of the TCR | 1.TCR resistance training:SLP pressed their index and middle fingers on the TCR of the patient, and instructed the patient to maintain the TCR with maximum force against the downward pressure of SLP's fingers |
TPR | To increase the muscle strength of the TPR | 1.Tongue-hold swallows:which involved wrapping a patient’s tongue with gauze, pulling it forward, and then instructing the patient to forcefully pull it back into the oral cavity against the resistance of traction and to swallow immediately |
To increase the muscle strength of the TPR | 2.TPR resistance training:SLP pressed their index and middle fingers on the TPR of the patient, and instructed the patient to maintain the TPR with maximum force against the downward pressure of SLP's fingers |
The whole tongue | To increase the whole tongue flexibility | 1.Tongue passive motor function training:SLP wrapped the patient's tongue with gauze and pulled it forward, including up, down, left and right directions.The patient complete 10 repetitions of elevation (up), 10 repetitions of depression (down), 10 repetitions of lateralization to the right (right) and 10 repetitions of lateralization to the left (left). |
To increase the tongue muscle fibre | 2.Low frequency electrical stimulation training:Low frequency electrical stimulation training | 10 min | 1 sessions a day | 10 days |
Abbreviation:s, second; min, minutes.
The inclusion criteria of the patients was as follows: (1) having a diagnosis of NPC confirmed by MRI and histologically diagnosed with malignant tumors in the nasopharynx;(2)dysphagia was diagnosed by VFSS17; (3) clinical examination showed no abnormalities in the oral cavity and intact dentition; (4) screening with a quick questionnaire detected impairment in hearing and comprehension. Individuals who scored > 24 on the Mini-Mental State Examination(MMSE)18 and < 24 on the Hearing Handicap Inventory for the Elderly-Screening(HHIE-S)19 were included in the study; (5) patients had to be fully aware and willing to participate in the therapy, as well as capable of giving informed consent; (6) adequate physical functioning was necessary to fulfill the exercise prescription requirements.
The exclusion criteria for all patients was as follows: (1) the history of neurogenic conditions that can lead to weakness in the muscles of the tongue, including stroke, Parkinson's disease, amyotrophic lateral sclerosis (ALS), tongue cancer, and laryngeal carcinoma; (2) recurrent or metastatic nasopharyngeal tumors; (3)oral structural abnormalities detected during clinical examination;(4)some patients were unable to complete the test and train due to oral pain and discomfort; (5)inability to comply with commands given by the tongue pressure sensors was observed; (6) patients were taken muscle relaxants; (7) unstable vital signs; and (8) patients or their family members exhibited uncooperative behavior.
This study underwent a thorough review and was approved by the Ethics Committee of XXX (Approval No:CUHK Attached SAN Medical Ethics [2021]02-200-01). All individuals participating in the study provided written informed consent for the utilization of their medical data and any remaining specimens.
Treatment
In this research, a total of 18 patients to evaluation from a team of medical professionals prior to the intervention. Following this, the medical team developed an training program focused on enhancing tongue function for all patients. The program was conducted by a proficient speech-language pathologist (SLP) possessing a 13-year background in dysphagia therapy. Throughout two weeks, the training sessions occurred once a day, five days a week, ensuring a high frequency and intensity of practice.The training program included intensive training on anterior tongue (TAR), center tongue (TCR), posterior tongue (TPR) and the whole tongue, as follows in Table 220–23.
Holding for 10s means that the patient holds the movement for 10s at the terminal end of completing the movement. Each training session consisted of 40 minutes of intensive training focused on tongue function, and the overall duration of the program was 1.2 hours. Patients were instructed to take a one-minute break after each basic training session and were allowed to perform oral cleaning during this interval. The medical team regularly evaluated the patients' progress and made necessary adjustments to the segmental tongue function training. Additionally, the SLP modified the training program according to each patient's individual needs.The exercise prescription was based on the meta-analysis by Banda et al.24, as well as the Korean version of clinical dysphagia rehabilitation guidelines25, and is clinically feasible.
Data collection
The tongue pressure and tongue endurance time before and after treatment were assessed by a flexible nine-sites tongue pressure sensor developed by our team(Fig. 1). The patients were in a seated position with the head in a neutral position in a quiet treatment room. The head position was kept constant during the examination. The assessor sits laterally to the patients and explains the purpose and methods of the examination(Fig. 2). Before the formal measurement, a complete practice was performed to ensure that the patient mastered the tongue pressure measurement method. A custom-made disposable film was used to wrap the sensor pad and placed on the surface of the tongue. The patients were then instructed to bite the first soft ring and hold the handle of the sensor themselves. Instructions were given on a flat panel monitor, providing guidance on how to perform the tongue pressure test and how to measure the tongue endurance time. Measurements were not recorded until the patient was unable to complete the instructions. After three tests had been completed, the maximum pressure value(The unit of pressure is kilopascals (kPa). Patients could rest for 15S between the two stress tests.) and the maximum tongue endurance time(The unit of endurance time is seconds(s). Patients could rest for 30S between endurance time tests. The tongue tolerance time was defined as the time that the patient's tongue pressure value was maintained at more than 50% of the maximum tongue pressure value.) at each site was displayed on the table(Fig. 3). The maximum tongue pressure value and maximum tongue pressure tolerance time of each patient were recorded before and after segmental tongue function training. The maximum tongue pressure and tongue endurance time were measured at 8 am before the first and the day after the last tongue strengthening training, respectively, to ensure consistent tongue muscle status.
All assessments were performed by an SLP with 8 years of experience to ensure the accuracy of the measurement data.
Data analysis
The measurement site design for this study was based on a previous research that found no notable variation in muscle fiber composition between the left, middle and right sides of the TAR, TCR and TPR. However, there were differences observed in muscle fibers from the anterior, middle and posterior parts of the tongue26, 27. To accurately capture these differences, the oral tongue was divided into three parts: TAR, TCR, and TPR28. Each part was further subdivided into three sites, with S1 to S3 representing TAR, S4 to S6 representing TCR, and S7 to S9 representing TPR(Fig. 1). The results obtained from the measurements were displayed on a tablet computer in real-time and recorded for analysis.
Tongue pressure measurement29
The defined pressure at each part (Px) was determined by calculating the average of the maximal tongue pressure obtained from the three tests.PTAR represents the mean maximum tongue pressure at the TAR part; PTCR represents the mean maximum tongue pressure at the TCR part; PTPR represents the mean maximum tongue pressure at the TPR part. The PTAR, PTCR and PTPR were compared before and after segmental tongue function training.
Endurance time30
The average endurance time of each section (ETx) was determined by calculating the average of endurance times obtained from three tests. ETTAR represents the mean maximum tongue endurance time of TAR part; ETTCR represents the mean maximum tongue endurance time of TCR part; ETTPR represents the mean maximum tongue endurance time of TPR part. The ETTAR, ETTCR and ETTPR were compared before and after segmental tongue function training.
Statistical Analysis
The statistical analyses for this study were conducted using SPSS 25.0 software. The paired t-test was used to compare the differences in tongue pressure and endurance time before and after treatment. The tongue pressure parameters (TAR, TCR, TPR) and endurance time parameters (TAR, TCR, TPR) all followed a normal distribution. The significance level for statistical significance was set at a P-value < 0.05.