Application value research of swallowing treatment device combined with swallowing rehabilitation training in the treatment of swallowing disorders after stroke

Abstract

BACKGROUND

Stroke is a common disabling disease, whether it is ischemic stroke or hemorrhagic stroke, both can result in neuronal damage, leading to various manifestations of neurological dysfunction.

AIM

To explore of the application value of swallowing treatment device combined with swallowing rehabilitation training in the treatment of swallowing disorders after stroke.

METHODS

This study selected 86 patients with swallowing disorders after stroke admitted to our rehabilitation department from February 2022 to December 2023 as research subjects. They were divided into a control group (n = 43) and an observation group (n = 43) according to the treatment. The control group received swallowing rehabilitation training, while the observation group received swallowing treatment device in addition to the training. Both groups underwent continuous intervention for two courses of treatment.

RESULTS

The total effective rate in the observation group (93.02%) was higher than that in the control group (76.74%) (P = 0.035). After intervention, the oral transit time, swallowing response time, pharyngeal transit time, and laryngeal closure time decreased in both groups compared to before intervention. In the observation group, the oral transit time, swallowing response time, and pharyngeal transit time were shorter than those in the control group after intervention. However, the laryngeal closure time after intervention in the observation group was compared with that in the control group (P = 0.142). After intervention, average amplitude value and duration of the genioglossus muscle group during empty swallowing and swallowing 5 mL of water are reduced compared to before intervention in both groups. After intervention, the scores of the chin-tuck swallowing exercise and the Standardized Swallowing Assessment are both reduced compared to pre-intervention levels in both groups. However, the observation group scores lower than the control group after intervention. Additionally, the Functional Oral Intake Scale scores of both groups are increased after intervention compared to pre-intervention levels, with the observation group scoring higher than the control group after intervention (P < 0.001). The cumulative incidence of complications in the observation group is 9.30%, which is lower than the 27.91% in the control group (P = 0.027).

CONCLUSION

The combination of swallowing therapy equipment with swallowing rehabilitation training can improve the muscle movement level of the genioglossus muscle group, enhance swallowing function, and prevent the occurrence of swallowing-related complications after stroke.

Key Words: Swallowing therapy device, Swallowing rehabilitation training, Stroke, Swallowing disorder, Swallowing function

Core Tip: The purpose of the study was to explore of the application value of swallowing treatment device combined with swallowing rehabilitation training in the treatment of swallowing disorders after stroke. The total effective rate in the observation group (93.02%) was higher than that in the control group (76.74%) (P < 0.05). The combination of swallowing therapy equipment with swallowing rehabilitation training can improve the muscle movement level of the genioglossus muscle group, enhance swallowing function, and prevent the occurrence of swallowing-related complications after stroke.

INTRODUCTION

Stroke is a common disabling disease, whether it is ischemic stroke or hemorrhagic stroke, both can result in neuronal damage, leading to various manifestations of neurological dysfunction[1]. Swallowing disorders are common sequelae following a stroke, which can not only lead to inadequate food intake resulting in electrolyte imbalances and malnutrition but also may cause coughing leading to pulmonary infections, choking, and even life-threatening situations for the patient[2]. Therefore, in clinical practice, it is necessary to provide active swallowing rehabilitation training for stroke patients. However, some patients cannot tolerate the discomfort associated with swallowing rehabilitation training, leading to poor compliance. As a result, the effectiveness of conventional swallowing rehabilitation training varies[3].

In recent years, the swallowing therapy device has emerged as a novel instrument for treating swallowing disorders following stroke. By placing electrodes in the throat, it delivers electrical pulses to stimulate nerves such as the glossopharyngeal, hypoglossal, and vagus nerves, enhancing the contraction function of swallowing muscles and re-establishing the swallowing reflex arc. This method causes minimal discomfort, requires low patient compliance, and is increasingly being utilized in clinical practice[4]. We hypothesized that the combination of the swallowing device and rehabilitation training would have better therapeutic value for patients with post-onset dysphagia. This study explores the value of combining swallowing therapy devices with rehabilitation training for treating swallowing disorders following stroke.

MATERIALS AND METHODS

General data

This retrospective study was approved by the Ethics Committee of Yixing Hospital of Traditional Chinese Medicine. This study collected 86 patient data with swallowing disorders following stroke, who were admitted to the Rehabilitation Department of our hospital from February 2022 to December 2023. Patients were divided into two groups based on treatment, with 43 cases in each group. In the control group, there were 24 males and 19 females, with ages ranging from 42 to 75 years old and an average age of (62.47 ± 8.74) years. The duration of stroke ranged from 1 to 3 months, with an average duration of (2.05 ± 0.43) months. Regarding the type of stroke, 28 cases were ischemic stroke, and 15 cases were hemorrhagic stroke. In the observation group, there were 25 males and 18 females, with ages ranging from 41 to 74 years old and an average age of (61.97 ± 9.07) years. The duration of stroke ranged from 1 to 3 months, with an average duration of (1.98 ± 0.47) months. Regarding the type of stroke, 30 cases were ischemic stroke, and 13 cases were hemorrhagic stroke. The general data such as the duration of illness and disease type were compared between the two groups.

Inclusion criteria: (1) Stroke refers to the standard of 'Chinese main cerebrovascular disease diagnosis points 2019[5], and is confirmed by magnetic resonance imaging or head computed tomography (CT); (2) age 40-75 years old; (3) conscious, simple mental state examination scale > 24 points; (4) stroke duration ≤ 3 months; (5) dysphagia refer to the 'Chinese expert consensus on the assessment and treatment of dysphagia[6], video swallowing angiography confirmed, and Kubota drinking water test grade III-V; and (6) understand the training content, and cooperate with the research, sign the consent form.

Exclusion criteria: (1) Dysphagia caused by head and neck structural lesions or neurological diseases; (2) dysphagia existed before stroke; (3) with important organ dysfunction; (4) the estimated survival time was less than 6 months; (5) with malignant tumors or systemic infectious diseases; (6) have a history of esophageal surgery; and (7) with hematopoietic system diseases.

Methods

The control group received swallowing rehabilitation training intervention. Patients were seated with their heads tilted toward the unaffected side for supine and prone swallowing training. If unable to sit, supine position was adopted with slight flexion and lateral tilting of the head, and the affected shoulder elevated for swallowing training. This included pharyngeal cold stimulation, sour stimulation, dry swallowing exercises, cough training, and respiratory training. Pharyngeal cold stimulation: Using an ice-cold cotton swab to stimulate the posterior pharyngeal wall, base of tongue, palate, uvula, and other areas in the patient. Dry swallowing exercises: Instructing the patient to perform dry swallowing movements and swallow saliva during training. Instructing patients in diaphragmatic breathing, pursed-lip breathing, and effective coughing exercises. Advising patients to place food on the healthy side of the mouth while eating, transitioning from liquid to semi-solid and soft foods gradually. Instructing patients to eat slowly to prevent aspiration and reflux.

In addition to the aforementioned interventions, the observation group received intervention with a swallowing therapy device, along with the same swallowing rehabilitation training as the control group. The device used was the Vitalstim swallowing therapy device from Beijing Pukangjian Company. According to the instructions, electrodes were placed and secured at the patient's throat. The display screen was activated, and the channel intensity was adjusted within the patient's tolerance range, typically ranging from 3.5 to 10 mA. The treatment duration with the swallowing therapy device was 20-30 minutes per session, once daily. Both groups underwent two weeks as one course of treatment, with two consecutive courses of intervention.

Criterion of therapeutical effect

Reference to the water swallow test criteria: Significant improvement is defined as patients having no swallowing difficulties, categorized as Grade I in the water swallow test. Effective improvement is defined as a reduction compared to before enrollment, categorized as Grade II in the water swallow test. Ineffective improvement is defined as no change in swallowing, categorized as Grade III to V in the water swallow test.

Detect method

Both groups of patients underwent video fluoroscopic swallowing examination before intervention and after two courses of intervention. The fluoroscopic instrument used was the Siemens digital fluoroscopy machine, with a recording speed of 30 frames per second. Barium sulfate suspension was mixed with thickening agents to create liquid, honey-thick, and pudding-like consistencies. Patients were seated in a lateral position for swallowing, and each swallow was administered with a 5 mL bolus. Parameters recorded included oral transit time, swallowing reflex, pharyngeal transit time, and laryngeal closure time.

The surface electromyography of the infrahyoid muscle group was detected before and after 2 courses of intervention. Guide the patient to take the supine position and relax the whole body. The magnetic stimulation coil was placed at the position tangent to the motor cortex of the mandibular hyoid muscle in the contralateral hemisphere. The main electrode of the surface electrode was placed 2 cm outside the midpoint of the mandibular hyoid line. The stimulation was performed with 100% resting motion threshold stimulation intensity. The average amplitude value (AEMG) and duration of the hyoid muscle group were recorded when swallowing and swallowing 5 mL water.

Marking criterion

Wakita water drinking test scoring[7]: (1) Grade I (1 point): Drinking 30 mL of warm water while seated, completed in a single swallow within 5 s without coughing; (2) Grade II (2 points): Drinking 30 mL of warm water while seated, completed in ≥ 2 swallows within 5 s without coughing; (3) Grade III (3 points): Drinking 30 mL of warm water while seated, completed in a single swallow without coughing but taking longer than 5 s; (4) Grade IV (4 points): Drinking 30 mL of warm water while seated, requiring > 2 swallows and accompanied by coughing; and (5) Grade V (5 points): Difficulty in drinking and accompanied by coughing.

The functional oral intake scale scoring[8] is as follows: (1) Level 1 (1 point): Tube dependency for all nutrition and hydration; (2) Level 2 (2 points): Intake of consistency-modified (pureed) foods; (3) Level 3 (3 points): Intake of liquidized (thin) fluids; (4) Level 4 (4 points): Intake of cohesive (soft) solids; (5) Level 5 (5 points): Intake of soft-solid foods; (6) Level 6 (6 points): Intake of regular foods that are chopped or minced; and (7) level 7 (7 points): Intake of regular foods without any modifications.

The standardized swallowing assessment scoring[9]: It consists of 19 items, including consciousness, head control, breathing, swallowing 5 mL of water, swallowing 60 mL of water, etc. The total score ranges from 18 to 46 points, with swallowing function negatively correlated with the score.

Complication

The incidence of aspiration pneumonia, choking cough and asphyxia in the two groups was recorded, and the incidence rate was counted.

Statistical Analysis

All the data in this study were processed by SPSS 25.0. The quantitative indicators that obey the normal distribution and meet the homogeneity of variance were described by the mean plus or minus standard deviation. The t test was used to compare the count data with the number of cases and the percentage. The χ² test was used to compare the theoretical frequency < 1, Fisher 's exact test was used, and the theoretical frequency ≥ 1 and ≤ 5, with the correction test. P < 0.05 was considered statistically significant.

RESULTS

Comparison of efficiency between two groups

The observation group had 19 cases showing significant improvement and 21 cases showing effectiveness, with a total effective rate of 93.02%; the control group had 11 cases showing significant improvement and 22 cases showing effectiveness, with a total effective rate of 76.74%. The total effective rate of the observation group was higher than that of the control group (P = 0.035) (Table 1).

Table 1 Comparison of efficiency between two groups, n (%).

Group	Number of samples	Significantly effective	Effective	Ineffective	Total effective rat
Control group	43	11 (25.58)	22 (51.16)	10 (23.26)	33 (76.74)
Observation group	43	19 (44.19)	21 (48.84)	3 (6.98)	40 (93.02)
χ2 value					4.441
P value					0.035

Comparison of TV video fluoroscopic swallowing examination before and after intervention between the two groups

The video fluoroscopic swallowing examinations before intervention were compared between the two groups (P > 0.05). The oral delivery time, swallowing reaction, pharyngeal delivery time and laryngeal closure time of the two groups after intervention were lower than those before intervention. The oral delivery time, swallowing reaction and pharyngeal delivery time of the observation group after intervention were shorter than those of the control group. However, the time of laryngeal closure after intervention in the observation group was compared with that in the control group (P = 0.142) (Table 2).

Table 2 Comparison of video fluoroscopic swallowing examination before and after intervention between the two groups.

Group	Number of samples	Oral delivery time		Swallowing reaction		Pharyngeal delivery time		Laryngeal closure time
		Before intervention	After intervention	Before intervention	After intervention	Before intervention	After intervention	Before intervention	After intervention
Control group	43	1.52 ± 0.53	0.89 ± 0.24a	1.12 ± 0.38	0.80 ± 0.37a	2.51 ± 0.45	1.76 ± 0.41a	0.70 ± 0.19	0.54 ± 0.13a
Observation group	43	1.56 ± 0.52	0.61 ± 0.20a	1.09 ± 0.42	0.56 ± 0.34a	2.47 ± 0.51	1.50 ± 0.34a	0.68 ± 0.21	0.50 ± 0.12a
t value		0.353	5.877	0.347	3.132	0.386	3.201	0.463	1.483
P value		0.725	0.000	0.729	0.002	0.701	0.002	0.644	0.142

^aP < 0.05 vs before intervention.

Comparison of surface electromyography of the genioglossus muscle group before and after intervention in both groups

The surface electromyography of the genioglossus muscle group before intervention was compared between the two groups (P = 0.945). After intervention, the AEMG and duration of the genioglossus muscle group during empty swallowing and swallowing 5mL of water decreased compared to before intervention in both groups. However, in the observation group, the AEMG and duration of the genioglossus muscle group during empty swallowing and swallowing 5mL of water were lower than those in the control group after intervention. The difference was statistically significant (Table 3).

Table 3 Comparison of surface electromyography of the genioglossus muscle group before and after intervention in both groups.

Group	Number of samples	Empty swallowing				Swallowing 5 mL of water
		AEMG (μV)		Duration (s)		AEMG (μV)		Duration (s)
		Before intervention	After intervention	Before intervention	After intervention	Before intervention	After intervention	Before intervention	After intervention
Control group	43	35.89 ± 7.94	28.75 ± 6.12a	3.89 ± 1.21	2.11 ± 0.82a	38.16 ± 8.95	29.11 ± 6.05a	3.64 ± 1.23	2.08 ± 0.74a
Observation group	43	36.01 ± 8.12	26.31 ± 4.96a	3.92 ± 1.17	1.47 ± 0.67a	37.96±9.41	25.21 ± 5.13a	3.71 ± 1.18	1.51 ± 0.45a
t value		0.069	2.031	0.117	3.963	0.101	3.224	0.269	4.316
P value		0.945	0.045	0.907	0.000	0.920	0.002	0.788	0.000

^aP < 0.05 vs before intervention.

AEMG: Average amplitude value.

Comparison of Wakita water drinking test scores, functional oral intake scale, and standardized swallowing assessment scores between the two groups

Comparison was made between the two groups regarding the Wakita water drinking test scores, functional oral intake scale (FOIS) scores, and standardized swallowing assessment (SSA) scores before intervention. There was no significant difference between the two groups and the difference was not statistically significant. After intervention, both groups showed a decrease in Wakita water drinking test scores and SSA scores compared to before intervention. In the observation group, these scores were lower than those in the control group after intervention. Additionally, both groups showed an increase in FOIS scores after intervention compared to before intervention, with the observation group scoring higher than the control group after intervention . The difference was statistically significant (Table 4).

Table 4 Comparison of Wakita water drinking test scores, functional oral intake scale scores, and Standardized swallowing assessment scores between the two groups.

Group	Number of samples	Wakita water drinking test scores		FOIS scores		SSA scores
		Before intervention	After intervention	Before intervention	After intervention	Before intervention	After intervention
Control group	43	4.58 ± 0.47	2.24 ± 1.05a	1.79 ± 0.74	4.46 ± 1.02a	32.52 ± 5.85	25.41 ± 4.11a
Observation group	43	4.62 ± 0.43	1.53 ± 0.81a	1.80 ± 0.78	5.53 ± 1.17a	31.97 ± 6.26	22.23 ± 3.95a
t value		0.412	3.511	0.061	4.520	0.421	3.658
P value		0.682	0.001	0.952	< 0.001	0.675	< 0.001

^aP < 0.05 vs before intervention.

FOIS: Functional oral intake scale; SSA: Standardized swallowing assessment.

Comparison of complications between two groups

The cumulative incidence of complications in the observation group, at 9.30%, was lower than that in the control group, at 27.91% (P = 0.027) (Table 5).

Table 5 Comparison of complications between two groups, n (%).

Group	Number of samples	Aspiration pneumonia	Choking coughing	Asphyxia	Cumulative complications
Control group	43	9 (20.93)	2 (4.65)	1 (2.33)	12 (27.91)
Observation group	43	3 (6.98)	1 (2.33)	0 (0.00)	4 (9.30)
χ2 value					4.914
P value					0.027

DISCUSSION

Swallowing is a complex neuro-muscular activity that requires precise interaction among different regions of the brain to coordinate the muscles involved in swallowing. Ischemic and hypoxic damage to brain functional areas following stroke can lead to swallowing dysfunction[10]. Based on the plasticity of swallowing motor cortex, active swallowing rehabilitation training is typically provided in clinical practice for post-stroke patients with swallowing disorders to promote central nervous system remodeling and regulation of swallowing function[11]. Traditional swallowing rehabilitation interventions, such as pharyngeal cold stimulation, dry swallowing exercises, and coughing respiratory training, stimulate brain input signals, promote connections between neurons around brain lesions and motor neurons, restore feedback pathways, and improve coordination and flexibility of pharyngeal muscles. However, some patients still exhibit unsatisfactory outcomes after swallowing rehabilitation interventions[12].

The swallowing therapy device is an auxiliary treatment device for swallowing disorders, which improves swallowing function by stimulating the activity of swallowing-related muscle groups through electrical stimulation[13]. Zhang et al[14] applied synchronized neuromuscular electrical stimulation during swallowing training to intervene in post-stroke swallowing disorders, and found that it could better alleviate swallowing difficulties. In this study, the observation group had a higher total effective rate. After intervention, both groups showed a decrease in Wakita Water Drinking Test scores and SSA scores compared to before intervention. Furthermore, in the observation group, the scores for Wakita Water Drinking Test and SSA were lower than those in the control group after intervention. Additionally, both groups showed an increase in FOIS scores after intervention compared to before intervention, with the observation group scoring higher than the control group after intervention. This result suggested that the combination of swallowing therapy device with rehabilitation training has a better improvement effect on swallowing disorders following stroke. However, the subjective nature of the above-mentioned scale scores for evaluating swallowing function exists. Therefore, this study attempted to use video fluoroscopic swallowing examination to objectively evaluate the improvement in swallowing function before and after intervention in patients. It was found that after intervention, both groups showed a decrease in oral transit time, swallow response, pharyngeal transit time, and laryngeal closure time compared to before intervention. Additionally, in the observation group, oral transit time, swallow response, and pharyngeal transit time were shorter than those in the control group after intervention, while laryngeal closure time was similar in both groups after intervention. This objective result confirms that the combination of swallowing therapy device with rehabilitation training helps improve swallowing function in patients with post-stroke swallowing disorders. This is because swallowing rehabilitation training can simultaneously stimulate the cortical sensory area of the central nervous system and the pharyngeal muscle group, preventing muscle atrophy[15]. The swallowing therapy device promotes muscle contraction in the throat through electrical stimulation, a process that does not require active cooperation from the patient, and its efficacy is not affected by the patient's level of cooperation[16]. Additionally, electrical stimulation can strengthen positive feedback and input to the central nervous system through the biofeedback mechanism, promoting the reorganization of swallowing central function, thereby achieving better therapeutic effects[17].

The strength and motor level of the submental muscle group play an important role in completing swallowing actions[18]. Therefore, this study attempted to explore the mechanism by which the swallowing therapy device combined with rehabilitation training alleviates swallowing disorders following stroke, starting from surface electromyography of the submental muscle group. The study found that after intervention, both groups showed a decrease in AEMG and duration during both dry swallowing and swallowing 5mL of water compared to before intervention. Additionally, in the observation group, the AEMG and duration of the submental muscle group during both dry swallowing and swallowing 5mL of water were lower than those in the control group after intervention. This result suggested that the combination of swallowing therapy device with rehabilitation training helps improve the muscle motor level of the submental muscle group. This is an important mechanism for improving swallowing function. This is because the electrical stimulation generated by the swallowing therapy device can stimulate the submental muscle group to produce instantaneous strong contractions. Repeated electrical stimulation can strengthen muscle strength, promote nerve repair, and regeneration[19,20].

The study also found that the observation group had a lower cumulative incidence of complications. This result suggests that the combination of swallowing therapy device with swallowing rehabilitation training can better reduce complications such as aspiration pneumonia, choking, and suffocation in patients with post-stroke swallowing disorders. This is related to the improvement in swallowing function and the increase in muscle strength and motor level of the submental muscle group facilitated by the swallowing therapy device.

CONCLUSION

In summary, the combination of swallowing therapy device with swallowing rehabilitation training for treating post-stroke swallowing disorders can improve the muscle motor level of the submental muscle group, enhance swallowing function, and prevent the occurrence of swallowing-related complications.