Effects of Shaker exercise in stroke survivors with oropharyngeal dysphagia

Abstract

BACKGROUND:

Dysphagia after stroke can cause a variety of complications, especially aspiration pneumonia, which can be life-threatening. Therefore, rehabilitation methods to reduce aspiration in patients with dysphagia are important.

OBJECTIVE:

In the present study, we aimed to investigate the effects of Shaker exercise on aspiration and oral diet level in stroke survivors with dysphagia.

METHODS:

Participants were randomly assigned to an experimental group (n = 16) or a control group (n = 16). Participants in the experimental group performed Shaker exercise and conventional dysphagia therapy, whereas those in the control group performed only conventional dysphagia therapy. All participants performed training 5 days a week for 4 weeks. Degree of aspiration was assessed using the Penetration-Aspiration Scale (PAS) based on videofluoroscopic swallowing study, while oral diet level was assessed using the Functional Oral Intake Scale (FOIS).

RESULTS:

The experimental group showed greater improvement on both the PAS (p < 0.05) and FOIS (p < 0.05) compared with the control group.

CONCLUSIONS:

The results of this study suggest that Shaker exercise is a effective exercise for recovery of swallowing function in stroke survivors with dysphagia.

Keywords

Dysphagia stroke swallowing aspiration-penetration

1 Introduction

Oropharyngeal dysphagia is a common problem in stroke survivors, which causes various difficulties in the oral and pharyngeal phases of swallowing due to changes in the motor, sensory, and mobility of orofacial, and hyolaryngeal muscles (Bahia, 2001). The pharyngeal phase is especially important as it is directly related to aspiration. Aspiration occurs when saliva or bolus enters the airway through the vocal cords instead of being swallowed into the esophagus. This can cause aspiration pneumonia, which can be fatal (Lim, 2012). Therefore, swallowing rehabilitation are important to ensure safe swallowing in stroke survivors with dysphagia.

Shaker exercise (SE) is a remedial method to train the swallowing-related muscles located in the front of the neck (Shaker et al., 2002). This head lift exercise involves mainly isometric and isokinetic contraction movements, and is performed by raising the head and looking at the toes while lying in a supine position. In the first part of the exercise, the patient sustains 3 head lifts held for 60 s with a 60-s rest between each lift. The second part of the exercise involves 30 repetitive head lifts at constant velocity without holding (Easterling, Grande, Kern, Sears, & Shaker, 2005).

Previous studies have found that SE is effective for activating the suprahyoid muscles (digastric, geniohyoid and mylohyoid muscles) located in the front of the neck and improving anterior and superior movements of the hyoid bone, as well as contributing to opening of the upper esophageal sphincter in elderly individuals and patients with various diseases (Easterling , & Shaker; 2000). As such, SE is a non-invasive intervention, does not require any additional cost or equipment, and can be carried out easily at the bedside with help and supervision of the caregiver. The present study aimed to investigate the effects of SE on swallowing function in stroke survivors with dysphagia.

2 Methods

2.1 Participants

Subjects were recruited from rehabilitation centers at 2 local hospitals in the Republic of Korea. Inclusion criteria were as follows: (1) dysphagia after stroke confirmed by a videofluoroscopic swallowing study (VFSS), (2) no significant cognitive deficit (Mini-Mental State Examination score >20), (3) above fair grade obtained on muscle testing of the neck, (4) symmetric posture of the neck, and (5) ability to swallow voluntarily. Exclusion criteria were as follows: (1) neck pain or neck surgery, (2) poor general condition precluding further participation in the experiment, (3) severe communication problem, (4) unstable medical condition, and (5) presence of a tracheostomy tube. The Institutional Review Board of Inje University approved the study (2-1041024-AB-N-01 – 20150609-HR-251), and all participants provided written informed consent prior to involvement in the study.

To perform sample size calculation, the G-power 3.1 software (University of Dusseldorf, Dusseldorf, Germany) was used. The power and the alpha levels were set at 0.60 and 0.05, respectively, and the effective size was set at 0.8. According to a prior analysis, each group required at least 12 subjects. Therefore, this study included 15 subject in the experimental group and 13 in the control group in preparation for drop-out cases.

2.2 Experimental procedures

This study had a 4-week, single-blind, 2-group, randomized, controlled design. Subjects were randomly allocated to either an experimental group (n = 16) or a control group (n = 15). Participants in the experimental group performed SE in addition to conventional dysphagia therapy (CDT), whereas those in the control group performed only CDT. CDT comprised orofacial muscle exercises, thermal tactile stimulation, and therapeutic or compensatory maneuvers. An experienced occupational therapist carried out CDT in all participants for 30 mina day, 5 days a week, for 4 weeks.

SE included isometric and isokinetic movements. First, participants sustained 3 head lifts held for 60 s without movement in the supine position; a 60-s rest was allowed between lifts. Then, participants performed 30 repetitive head lifts without holding in the same supine position. Participants lifted their head high enough to observe their toes without raising their shoulders. SE in the experimental group was carried out in hospital wards under supervision of caregivers, and performance status was assessed using a performance checklist.

2.3 Outcome measurement

The Penetration-Aspiration Scale (PAS) is a standard tool that reflects airway penetration and aspiration. Penetration is defined as passage of material into the larynx, which does not pass below the vocal folds, while aspiration refers to the action of material penetrating the larynx and entering the airway below the true vocal folds (Rosenbek, Robbinson, Roecker, Coyle, & Wood, 1996). The PAS utilizes an 8-point Likert scale based on depth of material invasion into the airway; higher score indicates higher aspiration severity.

The Functional Oral Intake Scale (FOIS) is a tool used to assess oral intake of foods and liquids type in dysphagic patients (Crary, Mann, & Groher, 2005). This tool consists of a 7-point scale; level 1 indicates complete impairment of oral intake whilst a level 7 rating indicates that the patient has complete oral intake regardless of food consistency or type.

2.4 Statistical analysis

All statistical analyses were performed using SPSS version 15.0 (IBM Corporation, Armonk, NY, USA). Normality of variables was assessed using the Shapiro-Wilk test. To evaluate intervention effects, the paired t test was used to compare outcome measures obtained before and after the intervention in each group. The independent t test was used to compare changes in outcome measures between groups. Significance was set at p < 0.05.

3 Results

In total, 31 participants completed the intervention. Three participants dropped out prior to follow-up because of hospital transfer, while 7 participants refused to continue because of fatigue or pain in the neck or general condition problem. Although participants who were able to raise their head while lying in a supine position were included in the experimental group, 5 participants (20%) dropped out during the intervention because of temporary fatigue or pain in the neck or abdominal muscles. This may be explained by the repetitive resistance movements performed during SE. Nevertheless, temporary fatigue and pain did not lead to any additional complications.

A summary of the clinical and demographic characteristics of the subjects is shown in Table 1. There were no significant differences in baseline characteristics between groups (p > 0.05). Both groups showed improved scores on both the PAS and FOIS (p < 0.05). However, the experimental group showed greater improvement than the control group, with significant differences in both PAS and FOIS scores between groups (p < 0.05) (Tables 2, 3).

Table 1
Characteristics of participants

Characteristics Experimental Group (n = 16) Control group (n = 15)

Age(year), mean±SD 60.81±10.85 60.40±10.50

Gender (male/female) 10/6 9/6

Type of stroke (Hemorrhage/Infarction) 7/9 3/12

Side of stroke (Right/Left) 7/9 10/5

Time since onset of stroke months, mean±SD 3.44±1.15 4.13±0.99

Characteristics	Experimental Group (n = 16)	Control group (n = 15)
Age(year), mean±SD	60.81±10.85	60.40±10.50
Gender (male/female)	10/6	9/6
Type of stroke (Hemorrhage/Infarction)	7/9	3/12
Side of stroke (Right/Left)	7/9	10/5
Time since onset of stroke months, mean±SD	3.44±1.15	4.13±0.99

SD: standard deviation.

Table 2

Clinical Parameters before and after Treatment

	Experimental group		Control group
	Pre-test	Post-test	Pre-test	Post-test
PAS	4.63(0.80)	3.19(0.54)^**	4.87(0.91)	4.27(0.88)^*
FOIS	3.13(0.95)	4.75(1.06)^**	3.20(0.67)	3.73(1.22)^*

The values are mean±standard deviation, PAS: Penetration-Aspiration Scale, FOIS: Functional Oral Intake Scale, ^*p < 0.05, ^**p < 0.01 by Paired-t test.

4 Discussion

Dysphagia treatment is usually performed by professional therapists, such as occupational therapists or speech language pathologists. However, it is crucial to educate patients to train on their own at the bedside, not just in the hospital treatment room, in order to improve swallowing function effectively. As such, the present study used SE as an intervention at the bedside in stroke survivors with dysphagia and studied its effects on swallowing function.

Although both groups showed decreases in aspiration, a significant difference was observed between the experimental and control groups after the intervention. Thus, we demonstrated that SE carried out in hospital wards under supervision of caregiversis effective for decreasing aspiration. Our finding can be explained by the following: SE is effective for activating the suprahyoid muscles, and with repetition of this exercise, such increase in muscle activation can result in muscle strengthening.

The normal swallowing mechanism is initiated by the swallowing reflex during the pharyngeal phase with suprahyoid muscle contraction (Ertekin & Aydogdu, 2006). Strong contraction of the suprahyoid muscles results in anterior-superior movement of the hyoid bone, which can influence the formation of residue in the epiglottic valleculae and pyriform sinuses, potentially leading to aspiration/penetration (Kendall & Leonard , 2003). In other words, SE is closely related to strengthening of the suprahyoid muscles, increasing movement of the hyoid bone, and protecting of the airway. Previous studies reporting the effect of SE on suprahyoid muscles activation in healthy adults have indicated an increase in muscle fiber recruitment (Woo, Won, & Chang, 2014). Increased muscle fiber recruitment produces greater muscle force, and repeated exercise has the potential to improve muscle strength. Therefore, we believe that SE has a positive effect on decreasing aspiration, which is in line with previous studies.

Table 3
Comparison of PAS, FOIS in Both Groups after Intervention

Experimental group Control group

PAS 3.19(0.54)^* 4.27(0.88)

FOIS 4.75(1.06)^* 3.73(1.22)

	Experimental group	Control group
PAS	3.19(0.54)^*	4.27(0.88)
FOIS	4.75(1.06)^*	3.73(1.22)

The values are mean±standard deviation, PAS: Penetration-Aspiration Scale, FOIS: Functional Oral Intake Scale, ^*p < 0.05 by independent t test.

Aspiration severity is closely related to L-tube feeding and oral diet level. Decreased aspiration implies that the patient can swallow food in a safer fashion, which may lead to removal of the L-tube and progression in oral diet level. Thus, we examined the L-tube removal rate and oral diet level after our 4-weekintervention, and found that the L-tube removal rate was 3 out of 9 (33%) in the experimental group, and 2 out of 8 (25%) in the control group. Moreover, a significant improvement in oral diet level was observed in the experimental group. Thus, this study confirmed that SE is effective for improving oral diet level in stroke survivors with dysphagia.

The present study confirmed that SE is an effective intervention for decreasing aspiration and improving oral diet level. However, there were several limitations. First, the relatively small sample size may have influenced the results. Therefore, the results cannot be generalized. Second, absence of follow-up after the intervention did not allow for determination of the long-term effects. Further studies with increased sample size and long-term follow-up are needed to evaluate the long-term effects of SE.

5 Conclusion

The present study confirmed that SE is an effective intervention for decreasing aspiration and improving oral diet level, which may lead to removal of the L-tube, in stroke survivors with dysphagia. Therefore, it is recommended that this intervention be carried out in hospital wards under supervision of caregivers.

Conflict of interest

This research was carried out without funding. No conflict of interest is declared.

References

Bahia

M. M.

, Mourao

L. F.

, & Chun

R. Y.

(2016). Dysarthria as a predictor of dysphagia following stroke. NeuroRehabilitation, 38(2), 155–162. doi: 10.3233/NRE-161305

Crary

M. A.

, Mann

G. D.

, & Groher

M. E.

(2005). Initialpsychometric assessment of a functional oral intake scale fordysphagia in stroke patients. Archives of Physical Medicineand Rehabilitation, 86(8), 1516–1520.

Easterling

, Grande

, Kern

, Sears

, & Shaker

(2005). Attaining and maintaining isometric and isokinetic goals of the shaker exercise. Dysphagia, 20(2), 133–138. doi: 10.1007/s00455-005-0004-2

Ertekin

, & Aydogdu

(2003). Neurophysiology of swallowing. Clinical Neurophysiology, 114(12), 2226–2244.

Ferdjallah

, Wertsch

J. J.

, & Shaker

(2000). Spectral analysis of surface Electromyography (EMG) of upper esophageal sphincter-opening muscles during head lift exercise. Journal of Rehabilitation Research and Development, 37(3), 335–340.

Freed

M. L.

, Freed

, Chatburn

R. L.

, & Christian

(2001). Electrical stimulation for swallowing disorders caused by stroke. Respiratory Care, 46(5), 466–474.

Humbert

I. A.

, Poletto

C. J.

, Saxon

K. G.

, Kearney

P. R.

, Crujido

, Wright-Harp

, & Ludlow

C. L.

(2006). The effect of surface electrical stimulation on hyolaryngeal movement in normal individuals at rest and during swallowing. Journal of Applied Physiology, 101(6), 1657–1663.

Kang

B. S.

, Oh

B. M.

, Kim

I. S.

, Chung

S. G.

, Kim

S. J.

, & Han

T. R.

(2010). Influence of aging on movement of the hyoid bone and epiglottis during normal swallowing: A motion analysis. Gerontology, 56(5), 474–482. doi: 10.1159/000274517.

Kendall

K. A.

, & Leonard

R. J.

(2001). Hyoid movement during swallowing in older patients with dysphagia. Archives Otolaryngology Head and Neck Surgery, 127(10), 1224–1229.

10.

Lim

K. B.

, Lee

H. J.

, Yoo

, & Kwon

Y. G.

(2014). Effect of low-frequency rTMS and NMES on subacute unilateral hemispheric stroke with dysphagia. Annals of Rehabilitation Medicine, 38(5), 592–602. doi: 10.5535/arm.2014.38.5.592.

11.

Matsuo

, & Palmer

J. B.

(2008). Anatomy and physiology of feeding and swallowing: Normal and abnormal. Physical Medicine and Rehabilitation Clinics of Narth America, 19(4), 691–707.

12.

Rosenbek

J. C.

, Robbins

J. A.

, Roecker

E. B.

, Coyle

J. L.

, & Wood

J. L.

(1996). A penetration-aspiration scale. Dysphagia, 11(2), 93–98. doi: 10.1007/BF00417897.

13.

Shaker

, Easterling

, Kern

, Nitschke

, Massey

, Daniels

, & Dikeman

(2002). Rehabilitation ofswallowing by exercise in tube fed patients with pharyngealdysphagia secondary to abnormal UES opening. Gastroenterology, 122(5), 1314–1321. doi: 10.1053/gast.2002.32999.

14.

Woo

H. S.

, Park

S. H.

, Jung

M. Y.

, Yoo

E. Y.

, & Park

J. H.

(2012). The effects of craniocervical flexion on activation of swallowing related muscles. Journal of Oral Rehabilitation, 39(11), 805–811. doi: 10.1111/j.1365-2842.2012.02338.x.

15.

Woo