To develop a quantitative and organ-specific practical test for the diagnosis and treatment of dysphagia based on assessment of stroke patients.
An initial test composed of 24 items was designed to evaluate the function of the organs involved in swallowing. The grading system of the initial test was based on the analysis of 50 normal adults. The initial test was performed in 52 stroke patients with clinical symptoms of dysphagia. Aspiration was measured via a videofluoroscopic swallowing study (VFSS). The odds ratio was obtained to evaluate the correlation between each item in the initial test and the VFSS. A polychotomous linear logistic model was used to select the final test items.
Eighteen of 24 initial items were selected as significant for the final tests. These 18 showed high initial validity and reliability. The Spearman correlation coefficient for the total score of the test and functional dysphagia scale was 0.96 (p<0.001), indicating a statistically significant positive correlation.
This study was carried out to design a quantitative and organ-specific test that assesses the causes of dysphagia in stroke patients; therefore, this test is considered very useful and highly applicable to the diagnosis and treatment of dysphagia.
Dysphagia is closely associated with stroke, and aspiration pneumonia is a main cause of death in stroke patients [
Given the above, this study aims to develop a practical assessment that allows evaluation of swallowing function in stroke patients with a risk of dysphagia in a quantitative and an organic-specific manner and evaluate their applicability.
This is a prospective study that was approved by the Institutional Review Board of Chungbuk National University Hospital. A total of 52 stroke patients aged 20 or older who underwent VFSS to evaluate dysphagia in a rehabilitation center from May to June 2015 were involved in this study. The mean age was 67.3 years, and 34 male and 18 female patients participated in this study (
This study was inspired by previous studies conducted by Mann et al. [
The sample test was performed on 8 specific categories (cognition, respiration, lip, tongue, chin, soft palate, vocal cord, and swallowing). These 8 categories were further sub-divided into 24 items.
The cognition evaluation was composed of orientation analysis and the ability to obey a 3-step command. The patients were asked about time, place, and person to investigate their mental orientation and, based upon the accuracy of their answers, the severity of cognitive deficit was classified as follows: normal, all correct answers; mild, 2 correct answers; moderate, 1 correct answer; severe, all wrong answers. The 3-step command was used to evaluate whether the patients were able to follow 3 consecutive commands. The patient's ability to obey the commands was similarly ranked: normal, obeyed all commands; mild, obeyed 2 commands; moderate, obeyed 1 command; severe, failed to obey all commands.
Respiratory evaluation was composed of analysis of cough, maximum number of repeated expirations, strength of expiration, and maximum phonation duration. The patients were instructed to cough violently and the tester evaluated their coughing function on a 3-stage scale (normal, able to cough violently; moderate, able to cough but not perfectly; severe, unable to cough) based on his observations. In order to evaluate the ability for repeated expiration, patients were asked to repeatedly expirate as quickly as possible. Expiration was classified as follows: normal, at least 18; mild, 15 to 17; moderate, 12 to 14; severe, fewer than 11 expirations. The strength of expiration was assessed by the maximum distance at which a patient could blow out a candle while maintaining a seated position on a stationary chair. The strength of expiration was divided into 4 categories based on the distance: normal, at least 90 cm; mild, 65 to 90 cm; moderate, 40 to 65 cm; severe, less than 40 cm. The patients were asked to phonate as long as possible in a sedentary position to evaluate maximum phonation time. It was measured twice and the maximum of the two measurements was recorded. Phonation time was ranked as follows: normal, at least 9 seconds; mild, 6 to 9 seconds; moderate, 3 to 6 seconds; severe, less than 3 seconds.
The symmetry of the lips, ability to repeat /pΛ/, sensation in the lips, and drooling were evaluated to assess lip function. The symmetry of the lips was categorized as either normal (bilateral symmetry) or abnormal (bilateral asymmetry) based on the tester's observations. The patients were asked to pronounce the bilabial sound /pΛ/ as many times as possible in 5 seconds, and the number of pronunciations was recorded and ranked as follows: normal, at least 24; mild, 21 to 23; moderate, 18 to 20; severe, less than 17. The tip of a cotton bud was lightly applied to the patient's lips to evaluate sensation, which was classified in one of the following 3 categories : normal, same for left and right; moderate, different for left and right; severe, no sensation on either side. Drooling was classified as normal (no drooling) or abnormal (drooling).
The function of the tongue was evaluated for strength, number of times the patient could repeat the sounds /tΛ/ and /kΛ/, and sensation. A tongue depressor was used to examine the strength of the tongue as assessed by the patient's ability to raise the tongue depressor. Tongue strength was given one of 4 rankings: normal, able to withstand strong resistance; mild, able to withstand weak resistance; moderate, able to raise the tongue without resistance; severe, unable to raise the tongue at all. Ability to repeat /tΛ/ was evaluated by asking patients to pronounce the alveolar consonant /tΛ/ as many times as possible in 5 seconds. Based on repetition number, one of 4 rankings was given: normal, at least 24 repetitions; mild, 22 to 24; moderate, 19 to 21; severe, less than 18. Evaluation of the ability to pronounce /kΛ/ was measured in the same manner and again given one of 4 rankings: normal, at least 24; mild, 21 to 23; moderate, 18 to 20; severe, less than 17. To assess sensation, the tongue was touched lightly with the tip of a cotton ball. Sensation on the left and right sides were measured and one of 3 rankings was given: normal, same for left and right; moderate, different for left and right; severe, no sensation on either side.
The inter-incisor distance and mastication ability were measured in order to quantitatively evaluate the function of the chin. Patients were asked to open their mouths as widely as possible and inter-incisor distance was recorded. The distance was classified into 4 categories: normal, at least 3.5 cm; mild, 2.5 to 3.5 cm; moderate, 1.5 to 2.5 cm; severe, less than 1.5 cm. In order to examine the ability to masticate, the patients were asked to chatter their teeth as quickly as possible for 5 seconds, as they would if they were eating. Mastication was divided into 4 categories: normal, at least 17; mild, 14 to 16; moderate, 11 to 13; severe, less than 10.
The movement of the soft palate was observed, and the pronunciation of an oral sound was evaluated in order to examine the health of the soft palate. First, the patients were asked to pronounce /α/ while their tongue was pressed with a tongue depressor to evaluate the lifting and symmetry of the soft palate. The health of the soft palate was divided into 4 categories: normal, normal lifting and symmetry of the soft palate; mild, a slight decline in lifting of the soft palate or a slightly asymmetric soft palate; moderate, a significant decline in lifting of the soft palate or a severely asymmetrical soft palate; severe, no lifting of the soft palate at all. Second, the patients were asked to form words and sentences involving oral sounds, and their sound-making ability was divided into 3 categories: normal, accurate pronunciation of the oral sound; moderate, incomplete pronunciation of the oral sound with a slight nasal sound; severe, too much nasal sound, based on the tester's observations. The words used in this test were '학교, 파도, 가구, 버스, 카드, and 바다' in Korean. The sentence used was '바닷가에 파도가 거세게 쳐요' in Korean.
A tester evaluated the extent of hoarseness during conversation in order to evaluate the function of the vocal cords. Function was assessed as either normal (no hoarseness at all) or abnormal (hoarseness). The patients were then asked to increase the volume of their voices from a whisper to a yell in order to examine their ability to control strength of phonation. Control was given one of 3 rankings: normal, able to control phonation; moderate, difficulty in controlling phonation; severe, unable to alter the volume of their voice, based on the tester's observations.
A syringe was used to place distilled water on each patient's tongue, 3 mL each time 3 consecutive times. The patients were asked to swallow the water in order to evaluate the swallowing ability. Aspiration of fluid (choking) subjectively divided into 4 categories: normal, no choking or hoarse voice after swallowing; mild, no choking but slight hoarseness of voice; moderate, no choking but a clearly identifiable hoarseness of voice; severe, choking. Next, excursion of thyroid cartilage was given one of 3 rankings: normal, clear excursion of thyroid cartilage; moderate, slight excursion of thyroid cartilage; severe, barely any excursion of thyroid cartilage. Last, latency of thyroid cartilage elevation was measured as the mean value of the 3 repeats. The latency of thyroid cartilage elevation was given one of 4 rankings: normal, less than 1 second; mild, 1 to 2 seconds; moderate, 2 to 3 seconds; severe, 3 seconds or more.
An overall evaluation was made by combining the means and standard deviations from each test item. The 'normal' state was based on the results of 50 healthy adults. The odds ratio between each evaluation item and the VFSS results was calculated to investigate the accuracy of the evaluation items. Each evaluation item was considered an independent variable, whereas aspiration on VFSS was the dependent variable. A polychotomous linear logistic model was used for regression analysis. Odd ratios, 95% confidence intervals (CIs) and p-values were obtained. From the initial 50 evaluation items, those with at least a 1.0 odds ratio and a p-value less than 0.1 were selected as final evaluation items. The final items were weighted on a relative scale. As a result, a 100-point evaluation was designed. Higher scores correspond with greater swallowing function. A receiver operator characteristic (ROC) curve was used to investigate the sensitivity, specificity, positive predictive value, negative predictive value and area under the ROC curve (AUC). The intra-class correlation coefficient (ICC) was used to evaluate inter-rater reliability, and a Spearman correlation coefficient was calculated to identify the relationship between total score and FDS score. The SAS ver. 9.3 program (SAS Institute Inc., Cary, NC, USA) was used to calculate all statistics.
The most significant odds ratio observed was that between aspiration of fluid and the VFSS results (12.0) (
There is often difficulty ensuring that stroke patients receive sufficient nutrition because of a risk of aspiration pneumonia caused by dysphagia. Sufficient nutrition helps stroke patients recover, and early detection and identification of dysphagia is crucial for prognosis [
A total of 24 evaluation items were identified that, in combination with one another, systematically and quantitatively evaluate the cognition, respiration, mouth function, pharynx health, larynx health, and swallowing ability in stroke patients. Then, a total of 18 items with odds ratios of at least 1.0 and p-values less than 0.1 were selected as the final items. As a result, a 100-point test was developed; higher scores on the test indicate more satisfactory swallowing function. Among the 18 items finally selected, a relatively high odds ratio was observed in the items related to the pharynx, such as aspiration of fluid, latency of thyroid cartilage elevation, and excursion of thyroid cartilage after swallowing distilled water. Therefore, we conclude that symptoms exhibited in the pharynx are of especial note in identifying dysphagia in stroke patients; this conclusion is in agreement with results from other studies done by Han et al. [
We found a close relationship of cognition and 3-step command understanding with aspiration. Better cognitive function clearly contributes to these abilities, which are also considered to be associated with dysphagia. Patients were asked to pronounce words and sentences involving oral sounds and then evaluated for excess nasality in order to investigate the correlation of soft palate function with dysphagia. We assumed that the odds ratios of oral abilities in words and sentences would be similar. Unexpectedly, the odds ratio of the ability to pronounce words was lower than that of the ability to pronounce sentences. In healthy people, nasal output tends to reduce as the length of the stimulus word gets longer [
The Burke dysphagia screening test, timed test, 3-oz water swallow test, bedside swallowing assessment, standardized swallowing assessment, GUSS, and TOR-BSST are the most commonly used screening tests today [
The Spearman correlation coefficient for total points and FDS score of the present test was 0.96 (p<0.001), which is a statistically significant positive correlation. FDS was developed using VFSS to confirm its validity [
The authors wished to use this study to identify, diagnose and set a treatment plan for dysphagia in stroke patients in an organ-specific manner; however, the authors have concluded that the this test is not suitable as a screening test since it has more evaluation items and requires far more hours to complete than other tests. It surpasses the usefulness limit of a screening tool [
The significance of this study is that is systematically evaluated the contribution of each organ to dysphagia in stroke patients. Evaluating swallowing function in a quantitative and organ-specific manner is a highly useful tool in planning the treatment and observing the progress of stroke patients.
This work was supported by the research grant of Chungbuk National University in 2014.
VFSS, videofluoroscopic swallowing study; OR, odds ratio; CI, confidence interval.
*p≤0.1.
PPV, positive predictive value; NPV, negative predictive value.