25.Dysphagia Evaluation(screening test)

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Explanation

We perform screening tests after evaluating systemic and local signs and symptoms. Even if we don't observe abnormal movement in either the mouth or in the pharynx at this point, we must confirm that their coordinated movements are working properly. Also, other things can sometimes compensate for impaired movement in one organ, so we should conduct screening tests routinely in order to evaluate function by function itself. This module explains the significance of screening tests and how to perform each type.

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Explanation

The term "screening test" conventionally refers to a test that is done to classify patients into groups, but the screening tests described in this module are primarily used to determine whether or not patients have aspirated. In this context, it's helpful to use standardized methods for reproducibility and information exchange. Screening tests must be safe, convenient, fast, and low-cost.

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Explanation

Indicators of the accuracy of screening tests include sensitivity and specificity. Sensitivity refers to the percentage of patients who actually have the disease (in this case, patients with aspiration actually observed on videofluoroscopy or videoendoscopy) who tested positive for aspiration. Specificity refers to the percentage of patients with a negative workup result for aspiration who tested negative for aspiration. The percentage of patients who tested positive for aspiration and were found to actually have aspirated by diagnostic workup is called the true positive rate, and the opposite is called the true negative rate. The matching rate of workup and test results is called the the accuracy rate.

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Explanation

In the repetitive saliva swallowing test (RSST),1)2) the number of times a patient can swallow in a 30-s period is measured by palpation of the thyroid cartilage with the index finger and middle finger. Less than 3 times in 30 s is a positive result that indicates aspiration. Research has shown that the interval between repeated swallows is prolonged in patients with dysphagia, and the sensitivity and specificity of this test have been reported as 0.98 and 0.66.

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Explanation

In the water swallowing test,3) patients are observed drinking 30 mL of room-temperature water to assess their swallowing function. Even though it was a great accomplishment to standardize water swallowing for this test, which was previously conducted solely based on experience, there is no information about its sensitivity or specificity and it is considered inappropriate to perform in patients with severe dysphagia due to the volume of water used.

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Explanation

In the modified water swallowing test (MWST),4) patients are observed swallowing 3 mL of cold water to determine whether they have aspirated. To prevent the water from flowing directly down the pharynx upon entering the mouth, it is necessary to pour the water into the floor of the mouth, but not on the tongue. After pouring the water, instruct the patient to swallow. If their score on this test is ≥ 4, the test is repeated up to 2 more times and the lowest score is taken as the result. The sensitivity and specificity of this test for detecting aspiration at a cutoff score of 3 points have been reported as 0.70 and 0.88.

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Explanation

The food test evaluates the ability to eat a teaspoon (about 4 g) of pudding.4) It differs from the MWST in that it evaluates the bolus residue in the oral cavity after swallowing. The sensitivity and specificity of this test for detecting aspiration at a cutoff score of 4 points have been reported as 0.72 and 0.62.

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Explanation

With both the MWST and the food test, the test is repeated a maximum of 3 times if the result is good, and the lowest score is taken as the result. Therefore, people who can't swallow well all 3 times can't score 4 or 5.

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Explanation

On pre- and post-swallowing radiography,5) plain radiographs in the lateral view are captured before and after swallowing 4 mL of liquid barium, and the patient's condition is evaluated by comparing those images and observing any episodes that occur during the test. The sensitivity and specificity of this test for detecting aspiration of liquids have been reported as 0.83 and 0.94.

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Explanation

The cough test is a screening test for silent aspiration.6)7)8) In this test, an irritant is sprayed into the air using a nebulizer and patients are asked to inhale orally to trigger the cough reflex. When they inhale 1.0% weight-by-volume citric acid-physiological saline from an ultrasonic nebulizer and cough is triggered ≥ 1 within 30s, presence of aspiration is indicated. The sensitivity and specificity for detecting silent aspiration have been reported as 0.92 and 0.94. Use of tartaric acid and use of a jet nebulizer have also been described.

11/19

Explanation

A flowchart for combining multiple tests to assess the patient's condition has also been published.4) The clinical tests used in the flowchart are the MWST, the food test, and pre- and post-swallowing radiography. When using the flowchart, we need to be aware that the goal is not to determine whether or not the patient has aspirated, but rather whether the patient can start direct swallowing training with food or needs a further evaluation by videofluoroscopy.

12/19

Explanation

To avoid serious risks when using the flowchart, the flowchart has 4 exclusion criteria and 3 checklist items. The listed clinical tests are not performed for patients who don't pass the prerequisites and who have the inappropriateness of three check items. If patients couldn't pass check items, the tests can be performed after correcting the defect check items.

13/19

Explanation

A flowchart that combines the cough test and the MWST has also been devised.7 This chart is not intended for only determining whether a patient has aspiration or not, but also for determining whether the the patient needs a further evaluation, like the previously mentioned flowchart.

14/19

Explanation

When using screening tests, be sure to keep in mind that each test gives only an outline of the patient's situation under defined conditions. In other words, even if one test shows that the patient's condition is poor, another test might have a good result. If several tests are performed, like in Example 1, the RSST alone might show that the patient is at high risk of aspiration, but results of the other tests might be relatively good. This kind of thing tends to happen with patients who do not follow instructions well. This patient obviously has aspirated, and their coughing during meals strongly appears to be associated with aspiration. Their meals should be changed immediately, and there should be no major problems if that is effective. The future rehabilitation plan should be determined after planning which tests to schedule. The patient in Example 2 has decent results for all tests but must be treated with aspiration pneumonia in mind because they have fever and possible silent aspiration. This must be managed immediately, and evaluation by videoendoscopy or videofluoroscopy should be performed soon.

15/19

Explanation

When using these as tests, it's a good idea to generally plan out who will perform the tests and at what timing. This promotes the intervention for swallowing disorders.

16/19

References

  1. Oguchi K, Saitoh E, Mizuno M, Baba M, Okui M, Suzuki M: The Repetitive Saliva Swallowing Test (RSST) as a Screening Test of Functional Dysphagia (1) Normal Values of RSS, Jpn J Rehabil Med,37(6): 375-382, 2000.
  2. Oguchi K, Saitoh E, Baba M, Kusudo S, Tanaka T, Onogi K: The Repetitive Saliva Swallowing Test (RSST) as a Screening Test of Functional Dysphagia (2) Validity of RSST, Jpn J Rehabil Med, 37(6): 383-388, 2000.
  3. Kubota T, et al.: Paralytic dysphagia in patients with cerebrovascular disease: Screening tests and their clinical applications, Sogo Rehabil, 10: 271-276, 1982.
  4. Tohara H, Saitoh E, Baba M, Onogi K, Uematsu H: A flowchart for evaluation of dysphagia without videofluorography. Jpn J Dysphagia Rehabil, 6(2): 196-206, 2002.
  5. Mizuno M, Saitoh E: Screening of dysphagia by X-ray: Comparing the findings of X-ray photos taken before and after swallowing contrast medium with those of videofluorography, Jpn J Rehabil Med, 37(10): 669-675, 2000.
  6. Wakasugi Y, Tohara H, Nakane A, Goto S, Ouchi Y, Mikushi S, Takeuchi S, Takashima M, Tsushima C, Chiba Y, Uematsu H: The utility of the cough test as a screening test for silent aspiration. Jpn J Dysphagia Rehabil, 12(2), 109-117, 2008
  7. Yoko Wakasugi, Haruka Tohara, Fumiko Hattori, Yasutomo Motohashi, Ayako Nakane, Shino Goto, Yukari Ouchi, Shinya Mikushi, Syuhei Takeuchi, Hiroshi Uematsu: Screening Test for Silent Aspiration at the Bedside, Dysphagia 23(4), 364-370, 2008
  8. Mitsuyasu Sato, Haruka Tohara, Takatoshi Iida, Satoko Wada, Motoharu Inoue, Koichiro Ueda: A Simplified Cough Test for Screening Silent Aspiration, Archives of Physical Medicine and Rehabilitation, 93, 1982-1986, 2012

Recommended readings

  1. Tohara H, ed.: A team approach to visiting dysphagia rehabilitation, Zennichi Byoin Publishing
  2. Uematsu H, ed.: An approach to dysphagia starting with in-home dentistry, Ishiyaku Publishers
  3. Mukai Y, Yamada Y, eds.: Dysphagia rehabilitation for dental students, 1st Edition, Ishiyaku Publishers
  4. Saitoh E, Mukai Y, eds.: Dysphagia rehabilitation, 2nd Edition, Ishiyaku Publishers
  5. Uematsu H, ed.: Understanding dysphagia rehabilitation I: Evaluation and management, Ishiyaku Publishers
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