Indian Journal of Physical Medicine and Rehabilitation
Volume 31 | Issue 2 | Year 2020

Improvement Pattern of VFSS due to Swallowing Maneuvers in Patients of Dysphagia with Posterior Circulation Stroke

Ayan Ghosal1, Saumen Kumar De2, Siddhartha Sinharay3, Biman K Ray4, Rajesh Pramanik5

1,3,5Department of Physical Medicine and Rehabilitation, Institute of Post Graduate Medical Education and Research and SSKMH, Kolkata, West Bengal, India
2Department of Physical Medicine and Rehabilitation, Calcutta National Medical College, Kolkata, West Bengal, India
4Department of Neurology, Bangur Institute of Neurology, Institute of Post Graduate Medical Education and Research and SSKMH, Kolkata, West Bengal, India

Corresponding Author: Siddhartha Sinharay, Department of Physical Medicine and Rehabilitation, Institute of Post Graduate Medical Education and Research and SSKMH, Kolkata, West Bengal, India, Phone: +91 9038337475, e-mail: dr.siddharthasinharay@gmail.com

How to cite this article Ghosal A, Kumar De S, Sinharay S, et al. Improvement Pattern of VFSS due to Swallowing Maneuvers in Patients of Dysphagia with Posterior Circulation Stroke. Indian J Phys Med Rehab 2020;31(2):24–30.

Source of support: Nil

Conflict of interest: None


Background: Post-stroke dysphagia is a leading cause of morbidity and prolonged hospitalization in stroke patients. The videofluoroscopic swallowing study (VFSS) is one of the gold standard techniques, designed to define the anatomy and physiology of a patient’s oropharyngeal swallow and examine the effectiveness of selected rehabilitation strategies designed to eliminate aspiration or excess oral or pharyngeal residue (the symptoms of patient’s dysphagia).

Objective: To quantify the improvement of patients’ subjective and objective symptoms.

Materials and methods: Institutional ethics committee clearance was taken. Fifteen patients were selected who satisfy our inclusion criteria. A prospective interventional study was done in the Department of PMR, IPGMEandR, Kolkata over 12 months. Videofluoroscopic swallowing study was done on all these patients at baseline and at 3 months interval and swallowing technique of head rotation to the paretic side applied at baseline and Mendelsohn maneuvers were applied for 3 months duration. Changes in VAS of swallowing (VASs) and videofluoroscopic dysphagia scale (VDS) were noted.

Inclusion criteria: Clinical dysphagia in a patient with confirmed posterior circulation stroke, after 2 weeks of stroke.

Exclusion criteria: Anterior circulation stroke, Other pertinent neurological diseases, any structural abnormalities in head-neck region, medically unstable patient.

Results: Statistically significant improvements of both VASs and VDS were seen in all the patients in follow-up visits with the application of selected swallowing techniques and maneuvers.

Conclusion: This study concludes that:

Keywords: Mendelsohn maneuver, Post-stroke dysphagia, Swallowing maneuvers, Videofluoroscopic swallowing study..


More than 50% of stroke survivors are affected by dysphagia.1 Fortunately, the majority of these patients recover swallowing function within 7 days, and only 11 to 13% remain dysphagic after 6 months.2,3

Among brainstem stroke patients, >70% had dysphagia and aspiration in videofluoroscopic swallowing study (VFSS).4

When lateral medullary syndrome patients were considered, dysphagia has been reported in 57 to 69%,58 though some studies showed less frequency.9 In a patient with medial medullary syndrome, dysphagia has been reported to 11,10 29,8 or as high as 78%.9

In acute stroke patients, it has been reported that severity was more important than location,11,12 and brainstem involvement increases readmission for dysphagia after 3 months.11

Another study with 64 patients in the post-acute phase of stroke concluded that pharyngeal safety was impaired more frequently in posterior territory lesion.13

The most feared complication of dysphagia after stroke is aspiration pneumonia. Dysphagia identified during bedside clinical examination was associated with an increase of 17% in the incidence of pulmonary infection compared to those that were not dysphagic (33 vs 16%, respectively).14

Dehydration and malnutrition also are common in dysphagic patients especially those who receive thickened liquids or modified diets. Forty-nine percent of stroke survivors admitted to a rehabilitation unit were malnourished, and that malnutrition was associated with dysphagia.15

Dysphagia can adversely impact the quality of life. Only 45% of dysphagic patients eat enjoyably, and eating is a time of panic or anxiety in about 41%.13,16 More than one-third of patients do not eat with others because of their dysphagia.16

The central pattern generator (CPG) for swallowing is located in the area of the nucleus tractus solitarius (NTS), the reticular formation, and nucleus ambiguus (NA) in the rostral and ventrolateral medulla.1419 Its intraneuronal network controls the timing of the deglutition phases and integrates sensory and supramedullary afferent with efferent processes.17

Since these areas are crucial for pattern generation, a lateral medullary stroke (Wallenberg’s syndrome) can cause severe dysphagia resulting in aspiration.20,21 This lesion affects the CPG and the CNs involved in swallowing; paralyzes or weakens the ipsilateral pharynx, larynx, and the soft palate; and initiation and coordination of the pharyngeal stage of deglutition. Notably, electrophysiological studies demonstrate that the acute disconnection of contralateral swallowing centers also takes place.20

Patients with swallowing disorders may be aware of their problem and able to describe it to the clinician in great detail or may be entirely oblivious to any difficulty with deglutition. Those patients reporting oropharyngeal swallowing disorders and can describe them are typically highly accurate in their localization and definition of the problems.22,23 However, if a patient denies having a swallowing problem, he or she is frequently oblivious about their swallowing problem, even severe.24

There are emerging pieces of evidence that early detection of dysphagia reduces not only pulmonary complications but also the length of hospital stays and overall healthcare costs for acute post-stroke patients.25,26

Clinical bedside evaluation can provide clinician data regarding cognition, current medical history, history of dysphagia, nutritional and respiratory status, oral anatomy, labial and lingual control, respiration and its relation to swallow, palatal function, pharyngeal wall contraction, laryngeal control, patients reaction to oral sensory stimulation and patient reaction in an attempt to swallow.27,28 Though clinical evaluation provides valuable information, sensitivity and specificity for aspiration risk are generally low.2931 Changes in voice quality32,33 and gag reflex33 were considered two important predictors of risk of aspiration. Clinicians could not identify aspiration in approximately 40% of time.34

The VFSS, also known as modified barium swallowing (MBS) study, is considered the gold standard for evaluation of oropharyngeal dysphagia.35,36 The VFSS allows the clinician to observe the important relationships between swallowing, food consistency, position, and ventilation.36,37 The process38 consisting of anteroposterior and lateral view of the oral-pharyngeal phase, with slow-motion features to allow characterization of the mechanism of swallowing and severity grading of dysfunction. Recent study reported early VFSS in acute stroke patients can determine most effective dysphagia management.39 During VFSS, some compensatory swallowing techniques can be applied to see any change. Swallowing techniques are designed to control the flow of food, eliminate the patient’s symptoms, and do not change the physiology of swallowing.40 It has been reported that rotating the head to the paretic side can direct the flow of bolus down a potentially more sensate and stronger side,41 though another study concluded no significant improvement in swallowing with head rotation in hemiplegic stroke patients.42

In lateral medullary syndrome, the upper esophageal sphincter did not open well and there was absent pharyngeal and upper esophageal contraction on manometry.43,44

Mendelsohn maneuver is designed to increase the extent and duration of laryngeal elevation and thus increase the duration and width of cricopharyngeal opening.45 Mendelsohn maneuver increases laryngeal elevation, hyoid superior displacement, and prolongs the duration of upper esophageal sphincter opening.46 A recent study used dynamic area detector CT to find out the effect of the Mendelsohn maneuver on swallowing in healthy subjects.47 They concluded that it increases hyoid elevation and pharyngeal constriction, but there was no significant increase in the duration of UES opening. It has been reported that there was a significant improvement in swallowing in acute stroke patients with conventional swallowing therapy, which includes Mendelsohn maneuver and head rotation to paretic side.48


This study is done to assess patients’ subjective and objective improvement in dysphagia after giving swallowing technique head rotation to paretic side and Mendelsohn maneuver and the role of VFSS.


This prospective interventional study was done in the outpatient and inpatient department of Physical Medicine and Rehabilitation, IPGMER AND SSKMH, KOLKATA, from September 2018 to September 2019 (12 months). It was calculated that at least 15 patients would be needed to detect a statistically significant change in videofluoroscopy. Patients with clinically and radiologically(MRI and/or MRA) confirmed cerebrovascular accident involving posterior circulation, with history of dysphagia attending OPD and IPD of the department of Physical Medicine and Rehabilitation, IPGMER AND SSKMH, KOLKATA, were included in this study depending on inclusion and exclusion criteria.

Inclusion Criteria

  • Age: 18 years and above.
  • Clinical dysphagia in patients with confirmed posterior circulation stroke.
  • More than equal to 2 weeks after stroke.
  • First incident of stroke.
  • Patient can communicate.

Exclusion Criteria

  • Anterior circulation stroke.
  • Other pertinent neurological diseases.
  • Any structural abnormality or neoplastic disease in the head-neck region.
  • Significant oropharyngeal incoordination.
  • Medically unstable patients.

Patients were allergic to barium salts.

After approval by IPGMEandR Research Oversight Committee, detailed history taking and thorough clinical examination were conducted for every patient after taking written informed consent. Age, sex, duration of disease, and baseline data on stroke were obtained. Mini-Mental Score of all patients was 28 or more. Baseline history regarding dysphagia and clinical examination of cranial nerves and neurological examination was done to determine the exact nature of the stroke and further define overall impairment. MRI scan report and MRA scan report, if available, were obtained to confirm the location of stroke. All the patients and caregivers were counselled regarding the disease processes and the mainstay of treatment and their active role in treatment process. After that, the baseline VAS score of swallowing (VASs) was obtained for every patient. VAS score of swallowing (VASs)45 is a 10-point score for subjective evaluation of dysphagia where 0 point means no difficulties at all and 10 points means maximum difficulties or unable to swallow. For VFSS, patients were positioned properly and lateral and posterior-anterior view video taken with 2 and 5 mL of liquid in each and every patient and videofluoroscopic dysphagia scale (VDS) score was obtained. Videofluoroscopic dysphagia scale46 is a 14-point score with a range from 0 to 100 (Table 1).

Compensatory swallowing technique rotation of head to the paretic side applied during baseline VFSS and change in VASs Score and VDS Score is noted (Figs 1 to 3).

All the patients and caregivers were taught the Mendelsohn’s maneuver thoroughly (Table 2). Patients were asked to do the Mendelsohn maneuver 45 minutes to 1 hour twice daily with a 2 to 3 hours gap between the sessions to prevent fatigue. Patients and caregivers were also advised regarding maintenance of nutrition and different food consistencies.

Follow-up assessment was done after 3 months and during follow-up VFSS was done again and no compensatory techniques were applied during follow-up VFSS. The data were tabulated in an excel sheet and analyzed according to standard statistical methods to fulfill the aims and objectives of the study. Baseline VASs were compared with baseline VASs with technique applied and VASs at 3 months, and baseline VDS score with baseline VDS with technique applied and VDS at 3 months. No comparison was done between baseline with technique scores and follow-up scores.

Process of Mendelsohn Maneuver


Statistica Version 8 [Tulsa, Oklahoma: StatSoft Inc., 2007] was used.

Comparison of individual parameters against baseline values done by Student’s paired t-test. During analysis, p %3C; 0.05 was considered statistically significant. All numerical variables are normally distributed by Kolmogorov–Smirnoff goodness-of-fit test. There was no drop out in this study.

Table 1: Videofluoroscopic dysphagia scale (VDS)
ParametersCoded valueScore (Max.)
Lip closure
Bolus formation
Tongue to palate contact
Premature bolus loss
Oral transit time
≤1.5 seconds03
>1.5 seconds3
Triggering of pharyngeal swallow
Vallecular residue
Laryngeal elevation
Pyriform sinus residues
Coating of the pharyngeal wall
Pharyngeal transit time
≤1.0 s06
>1.0 s6
Supraglottic penetration6
Subglottic aspiration12

The range of age was 37 to 78 years, with a mean age of 56.80 ± 12.02 years. Ten patients (67%) were male and 5 patients (33%) were female. The baseline VASs score was 8.13 ± 0.74 and the VDS score was 54.43 ± 11.23. Among 15 patients, 7 (46.67%) patients had aspiration, and 4 (26.67%) patients had supraglottic penetration in videofluoroscopy. There was significant improvement (p < 0.001) in both VASs score and VDS score with head rotation to the paretic side (Table 2). Significant improvement of both the parameters was found after 3 months follow-up (p < 0.001) (Table 3 and Figs 1 to 4).

Table 2: VDS and VASs scores comparison between baseline parameters and baseline with technique (head rotation to paretic side) parameters
ParametersBaselineBaseline with tech.p value
VDS54.43 ± 11.2347.13 ± 10.73<0.001
VASs8.13 ± 0.746.53 ± 0.64<0.001
Table 3: VDS and VASs scores comparison between baseline parameters and 3 months parameter
ParametersBaseline3 monthsp value
VDS54.43 ± 11.2348.07 ± 10.68<0.001
VASs8.13 ± 0.746.67 ± 0.98<0.001

Fig. 1: VDS scores comparison between baseline parameter and baseline with technique (head rotation to paretic side) parameter

Fig. 2: VASs scores comparison between baseline parameter and baseline with technique (head rotation to paretic side) parameter

Fig. 3: VDS scores comparison between baseline parameter and 3 months parameter

Fig. 4: VASs scores comparison between baseline parameter and 3 months parameter


The range of age group of patients were 37 to 78, which was similar to Priya et al.47 All these patients had symptoms of dysphagia, but only four patients had a cough with a change in voice during bedside swallowing examination. No patients had altered gag reflex. In VFSS, we found supraglottic penetration in four patients, and aspiration (Fig. 4) in seven patients. We found that though the change in voice clinically correlates with videofluoroscopy findings, only 26.67% of patients had clinical symptoms of a total of 73.33% of patients who diagnosed as having penetration or aspiration in videofluoroscopy. This concludes that clinical examination was inaccurate in diagnosing aspiration. Similar findings were also reported in their study by Terre and Mearin.12 As posterior circulation stroke itself a risk factor for aspiration, VFSS is essential in evaluating these patients. The baseline VAS of swallow (VASs) was 8.14 ± 0.74, which was quite higher than a study done by Bulow et al.45 This is probably because their study included more chronic patients and excluded brainstem stroke. In our study, we found most of our patients’ pharyngeal phase of swallowing was affected. This finding was similar to the studies of Martino et al.42 and Logemann et al.41 Similar finding was also reported by Priya et al.47 The baseline VDS score was 54.43 ± 11.23, quite higher than a study done by Park et al.,48 who included unilateral hemispheric stroke and post 1-month stroke. Pyriform fossa residue has been given a higher value (13.5) in the VDS score. So, the mean VDS in our study was higher probably because we included post circulation stroke patients and more acute patients (2 weeks). In the videofluoroscopic study, there was an improvement in swallowing in all the patients with head rotation to the paretic side and statistically significant improvement (p < 0.001) seen in VDS and Visual Analog Scale for swallowing. This finding was similar to Logemann et al.40

Fig. 5: In a patient with a lateral medullary syndrome, P-A view shows vallecular and pyriform residue

Fig. 6: Improve on right (paretic) side head rotation

Fig. 7: Improve on right (paretic) side head rotation

Fig. 8: Improvement on right (paretic) side head rotation

Fig. 9: Silent aspiration

In a study by McCullogh et al.,44 Mendelsohn maneuver was used to see any physiological change in swallowing, and participants performed them at home as an exercise program, but not during swallowing or VFSS examination. We considered a similar program in our study. Though sEMG biofeedback measure was not used during training of the Mendelsohn maneuver.

There was an improvement in swallowing and statistically significant improvement seen both in the VDS and visual analog scale for swallowing which was similar to McCullogh et al.44

No comparison was done between the swallowing technique and the Mendelsohn maneuver.

No major complications were seen in the patients.

Figs 5 to 8: In a patient with a lateral medullary syndrome, P-A view shows vallecular and pyriform residue (Fig. 5); improvement on right (paretic) side head rotation (Figs 6 to 8).4952


It was a short-term study and the study group was very small. No control group was there and no long-term follow-up was done. Participants did the Mendelsohn maneuver at home and so compliance with the maneuver could not be ensured. sEMG biofeedback measure was not used during training of Mendelsohn maneuver, so proper technique could not be ensured and can decrease effectiveness. No comparison was done between the swallowing technique and Mendelsohn maneuver, so which of them is more effective.


Swallowing difficulty involved mainly the pharyngeal phase in the patients with posterior circulation stroke and a VFSS is an essential part of an evaluation to diagnose aspiration and silent aspiration in these patients. The compensatory technique of rotation of the neck to the paretic side and can improve the dysphagia symptoms and the Mendelsohn maneuver can improve and maintain the improvement of dysphagia symptoms in patients with posterior circulation stroke. Videofluoroscopy is helpful to objectively quantify the improvement of dysphagia symptoms with different swallowing techniques and maneuvers.


1. Martino R, Foley N, Bhogal S, et al. Dysphagia after stroke: incidence, diagnosis, and pulmonary complications. Stroke 2005;36(12):2756–2763. DOI: 10.1161/01.STR.0000190056.76543.eb.

2. Smithard DG, O’Neill PA, England RE, et al. The natural history of dysphagia following a stroke. Dysphagia 1997;12(4):188–193. DOI: 10.1007/PL00009535.

3. Mann G, Hankey GJ, Cameron D. Swallowing function after stroke: prognosis and prognostic factors at 6 months. Stroke 1999;30(4):744–748. DOI: 10.1161/01.STR.30.4.744.

4. Singh S, Hamdy S. Dysphagia in stroke patients. Postgrad Med J 2006;82(968):383–391. DOI: 10.1136/pgmj.2005.043281.

5. Norrving B. Medullary infarcts and hemorrhages. In: ed. J, Bogousslavsky L, Caplan ed. Stroke Syndromes.Cambridge: Cambridge UniversityPress; 2001. 534–539.

6. Kim JS, Lee JH, Suh DC, et al. Spectrum of lateral medullary syndrome: correlation between clinical findings and magnetic resonance imaging in 33 subjects. Stroke 1994;25(7):1405–1410. DOI: 10.1161/01.STR.25.7.1405.

7. Kim JS. Pure lateral medullary infarction: clinical-radiological correlation of 130 acute, consecutive patients. Brain 2003;126(8):1864–1872. DOI: 10.1093/brain/awg169.

8. Kameda W, Kawanami T, Kurita K, et al. Lateral and medial medullary infarction: a comparative analysis of 214 patients. Stroke 2004;35(3):694–699. DOI: 10.1161/01.STR.0000117570.41153.35.

9. Kwon M, Lee JH, Kim JS. Dysphagia in unilateral medullary infarction lateral vs medial lesions. Neurology 2005;65(5):714–718. DOI: 10.1212/01.wnl.0000174441.39903.d8.

10. Kim JS, Kim HG, Chung CS. Medial medullary syndrome: reports of 18 new patients and a review of the literature. Stroke 1995;26(9):1548–1552. DOI: 10.1161/01.STR.26.9.1548.

11. Arnold M, Liesirova K, Broeg-Morvay A, et al. Dysphagia in acute atroke: incidence, burden and impact on clinical outcome. PLoS ONE 2016;11(2):e0148424. DOI: 10.1371/journal.pone.0148424.

12. Falsetti P, Acciai C, Palilla R, et al. Oropharyngeal dysphagia after stroke: incidence, diagnosis, and clinical predictors in patients admitted to a neurorehabilitation unit. J Stroke Cerebrovascu Dis 2009;18(5):329–335. DOI: https://doi.org/https://doi.org/10.1016/j.jstrokecerebrovasdis.2009.01.009.

13. Terre R, Mearin F. Oropharyngeal dysphagia after the acute phase of stroke: predictors of aspiration. Neurogastroenterol Motil 2006;18(3):200–205. DOI: 10.1111/j.1365-2982.2005.00729.x.

14. Smithard DG, O’Neill PA, Park C, et al. Complications and outcome after acute stroke. does dysphagia matter? Stroke 1996;27(7):1200–1204. DOI: 10.1161/01.STR.27.7.1200.

15. Finestone HM, Greene-Finestone LS, Wilson ES, et al. Malnutrition in stroke patients on the rehabilitation service and at follow-up: prevalence and predictors. Arch Phys Med Rehabil 1995;76(4):310–316. DOI: 10.1016/S0003-9993(95)80655-5.

16. Ekberg O, Hamdy S, Woisard V, et al. Social and psychological burden of dysphagia: its impact on diagnosis and treatment. Dysphagia 2002;17(2):139–146. DOI: 10.1007/s00455-001-0113-5.

17. Broussard DL, Altschuler SM. Brainstem viscerotopic organization of afferents and efferents involved in the control of swallowing. Am J Med 2000;108(Suppl 4a):79S–86S. DOI: 10.1016/S0002-9343(99)00343-5.

18. Jean A. Brain stem control of swallowing: neuronal network and cellular mechanisms. Physiol Rev 2001;81(2):929–969. DOI: 10.1152/physrev.2001.81.2.929.

19. Jean A. Brainstem organization of the swallowing network. Brain Behav Evol 1984;25(2-3):109–116. DOI: 10.1159/000118856.

20. Aydogdu I, Ertekin C, Tarlaci S, et al. Dysphagia in lateral medullary infarction (Wallenberg’s syndrome): an acute disconnection syndrome in premotor neurons related to swallowing activity? Stroke 2001;32(9):2081–2087. DOI: 10.1161/hs0901.094278.

21. Kim H, Chung CS, Lee KH, et al. Aspiration subsequent to a pure medullary infarction: lesion sites, clinical variables, and outcome. Arch Neurol 2000;57(4):478–483. DOI: 10.1001/archneur.57.4.478.

22. Kirchner JA. Pharyngeal and esophageal dysfunction: the diagnosis. Minn Med 1967;50:921–924.

23. Logemann JA. Evaluation and Treatment of Swallowing Disorders.Austin: Pro-Ed; 1998. p.1.

24. Logemann J. Evaluation and Treatment of Swallowing Disorders.Austin: Pro-Ed; 1998. p.152.

25. Hinchey JA, Shephard T, Furie K, et al. Formal dysphagia screening protocols prevent pneumonia. Stroke 2005;36(9):1972–1976. DOI: 10.1161/01.STR.0000177529.86868.8d.

26. Martino R, Pron G, Diamant NE. Screening for oropharyngeal dysphagia instroke: insufficient evidence for guidelines. Dysphagia 2000;15(1):19–30. DOI: 10.1007/s004559910006.

27. Griffin K, et al. Swallowing training for dtshagic patients. Arch Phys Med Rehabil 1974;55:467–470.

28. Linden and Seibeus, 1980. Videofluoroscopy: Use in evaluation and treatment of Dysphagia. The American Speech-Language Hearing Association Annual Meeting, Detroit.

29. Mann G, Hankey GJ, Cameron D. Swallowing disorders following acute stroke: prevalence and diagnostic accuracy. Cerebrovasc Dis 2000;10(5):380–386. DOI: 10.1159/000016094.

30. Daniels SK, Brailey K, Priestly DH, et al. Aspiration in patients with acute stroke. Arch Phys Med Rehabil 1998;79(1):14–19. DOI: 10.1016/S0003-9993(98)90200-3.

31. Langmore SE, Terpenning MS, Schork A, et al. Predictors of aspiration pneumonia: how important is dysphagia? Dysphagia 1998;13(2):69–81. DOI: 10.1007/PL00009559.

32. Horner J, Massey EW. Silent aspiration following stroke. Neurology 1988;38(2):317–319. DOI: 10.1212/WNL.38.2.317.

33. Horner J, Brazer SR, Massey EW. Aspiration in bilateral stroke patients: a validation study. Neurology 1993;43(2):430–433. DOI: 10.1212/WNL.43.2.430.

34. Gonzalez-Fernandez M, Sein MT, Palmer JB. Clinical experience using the mann assessment of swallowing ability for identification of patients at risk for aspiration in a mixed-disease population. Am J Speech Lang Pathol 2011;20(4):331–336. DOI: 10.1044/1058-0360(2011/10-0082).

35. Palmer JB, Kuhlemeier KV, Tippett DC, et al. A protocol for the videofluorographic swallowing study. Dysphagia 1993;8(3):209–214. DOI: 10.1007/BF01354540.

36. Martin-Harris B, Brodsky MB, Michel Y, et al. MBS measurement tool for swallow impairment—MBSImp: establishing a standard. Dysphagia 2008;23(4):392–405. DOI: 10.1007/s00455-008-9185-9.

37. Martin-Harris B, Jones B. The videofluorographic swallowing study. Phys Med Rehabil Clin N Am 2008;19(4):769–785. DOI:viii. 10.1016/j.pmr.2008.06.004.

38. Logemann JA. Manual for the Videofluorographic Study of Swallowing, 2.,Austin, TX: Pro-Ed, Inc; 1993.

39. Kim SB, Lee SJ, Lee KW, et al. Usefulness of early videofluoroscopic swallowing study in acute stroke patients with dysphagia. Ann Rehabilitat Med 2018;42(1):42–51. DOI: https://doi.org/10.5535/arm.2018.42.1.42.

40. Logemann J. Evaluation and Treatment of Swallowing Disorders.Austin: Pro-Ed; 1998. p.196.

41. Logemann JA, Kahrilas PJ, Kobara M, et al. The benefit of head rotation on pharyngoesophageal dysphagia. Arch Phys Med Rehabilitat 1989;70:767–771.

42. Lee H, Rho H, Cheon HJ, et al. Selection of head turn side on pharyngeal dysphagia in hemiplegic stroke patients: a preliminary study. Brain Neurorehabil 2018;11(2):e19. DOI: 10.12786/bn.2018.11.e19.

43. Logemann JA. Evaluation and Treatment of Swallowing Disorders.Austin: Pro-Ed; 1998. pp.1–7.

44. Martino R, Terrault N, Ezerzer F, et al. Dysphagia in a patient with lateral medullary syndrome: insight into central control of swallowing. Gastroenterology 2001;121(2):420–426. DOI: 10.1053/gast.2001.26291.

45. Bartolome G, Neumann S. Swallowing therapy in patients with neirological dysfunction. Dysphagia 1993;8(2):146–149. DOI: 10.1007/BF02266995.

46. McCullough GH, Kamarunas E, Mann GC, et al. Effects of Mendelsohn maneuver on measures of swallowing duration post stroke. Top Stroke Rehabil 2012;19(3):234–243. DOI: 10.1310/tsr1903-234.

47. Inamoto Y, Saitoh E, Ito Y, et al. The Mendelsohn maneuver and its effects on swallowing: kinematic analysis in three dimensions using dynamic area detector CT. Dysphagia 2018;33(4):419–430. DOI: https://doi.org/10.1007/s00455-017-9870-7.

48. Jongprasitkul H, Kitisomprayoonkul W. Effectiveness of conventional swallowing therapy in acute stroke patients with Dysphagia. Rehabil Res Pract 2020;2020:1–5. DOI: https://doi.org/10.1155/2020/2907293.

49. Bülow M, Speyer R, Baijens L, et al. Neuromuscular electrical stimulation (NMES) in stroke patients with oral and pharyngeal dysfunction. Dysphagia 2008;23(3):302–309. DOI: https://doi.org/10.1007/s00455-007-9145-9.

50. Han TR, Paik NJ, Park JW, et al. The prediction of persistent Dysphagia beyond six months after stroke. Dysphagia 2008;23(1):59–64. DOI: https://doi.org/10.1007/s00455-007-9097-0.

51. Priya CM, Menon JR. Cricopharyngeal dysfunction in lateral medullary syndrome. J Laryngol Voice 2014;4(1):21–27. DOI: 10.4103/2230-9748.141461.

52. Park JW, OH JC, Lee JW, et al. The effect of 5Hz high‐frequency rTMS over contralesional pharyngeal motor cortex in post‐stroke oropharyngeal dysphagia: a randomized controlled study. Neurogastroenterol Motil 2013;25(4):324–e250. DOI: 10.1111/nmo.12063.

© The Author(s). 2020 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by-nc/4.0/), which permits unrestricted use, distribution, and non-commercial reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.