Dysarthria Screening | Detect Dysarthria in an Instant with STAD Oral Diadochokinesis and Oral Movement

• Can Dysarthria Really Be Detected “In an Instant”?

You're probably curious about how dysarthria is screened using the STAD, which we'll explain in detail here. To do so, we’ll walk through a real case of mild dysarthria.

By the end of this article, you’ll be equipped to spot dysarthria without missing a beat.

Let’s dive in! 

■ Table of Contents

1. Oral Diadochokinesis
   1. Evaluation method

   2. Watch a Real Case

   3. Distortions in /ka/: A Key Indicator for Dysarthria
2. Oral Movement
   1. Evaluation method
   2. The Evidence-Based Tool for Dysarthria Screening

Slow, low-effort alternating movements cannot detect mild dysarthria. The scoring criteria ask not only whether the patient can repeat the sounds, but also whether they can articulate them fluently and rhythmically.

In the STAD Oral Diadochokinesis test, the sounds /pa/ (bilabial), /ta/ (alveolar), and /ka/ (velar) are used. The subject repeats these sounds, and speech rate, accuracy, and coordination are measured.

This is a case after experiencing a cerebral infarction.

Quite a few licensed SLPs should detect the speech abnormalities in this case, right?

• /pa/ is somewhat too slow, and there is some hesitancy.
• /ta/ shows distortion, resembling the sound /ts/.
• /ka/ exhibits insufficient contact between the tongue and palate, with undershooting and weak plosiveness.

The scoring criteria for the STAD Oral Diadochokinesis test focus on whether the sounds are produced fluently and rhythmically. In the case shown in the video, all the /pa/, /ta/, and /ka/ sounds would be rated as "fail."

It should be noted that in this case, dysarthria is hardly noticeable in everyday conversation, and no issues in communication have been observed. However, dysarthria can be detected with the /pa/ /ta/ /ka/ sequence in the STAD Diadochokinesis test.

I hope this has proven to you that this method can identify dysarthria in an instant, even in a very mild case. 

Generally, the consonant /ka/ has the highest detection power. This is because quantitative analysis of 45 cases in the acute phase shows that it has the lowest accuracy rate.

Clinically, many cases show more significant distortions in /ka/ compared to /pa/ and /ta/. Boldly speaking, I would even say that no dysarthria exists without distortion in /ka/.

I hope this can be useful as a method to identify dysarthria in an instant.

Next, I will explain the benefits of the STAD oral movement test and its supporting evidence.

Visually inspect the function of the oral articulators. If there are no issues with range of motion, speed of movement, or dexterity, it is marked as "pass."

This is not an item for evaluating auditory comprehension, so prompting through visual demonstration (imitation) is allowed.

Instruction: "Please copy me. Lick your upper lip."

Scoring: If the tongue extends beyond the upper lip, it is marked as "pass."

Instruction: "Wiggle your tongue outside your mouth."

Scoring: If the range of motion (ROM) extends beyond both corners of the mouth and the movement speed reaches 2 cycles per second, it is marked as "pass." Compensatory movement of the jaw is allowed, but it should be noted in the response section.

Instruction: "Move your tongue in and out."

Scoring: If the ROM extends beyond the lips and the movement speed reaches 2 cycles per second, it is marked as "pass." Deviation of the tongue is allowed, but it should be noted in the response section.

Instruction: "Puff out your cheeks."

Scoring: If the cheeks are puffed out, it is marked as "pass." However, if air leaks from the corners of the mouth, it is marked as "fail."

You can use the STAD articulation test as an evidence-based screening tool. This is because the STAD articulation test has demonstrated validity in the evaluation of articulation function.

Citing the Folia Phoniatr Logop. (Araki, 2021), the results of the STAD test conducted on 314 cases after brain injury are shown.

The vertical axis of the graph represents each test item of the STAD, while the horizontal axis represents the effect size (phi coefficient) indicating the strength of the association between each test item and the three types of disorders.

The factors for the three disorders and the effect size for each test are shown in different colors:

• Aphasia is represented in orange
• Dysarthria in green
• Other higher cognitive dysfunctions in navy blue

The STAD consists of three domains: verbal, articulation, and non-verbal. The top section of the graph corresponds to verbal tests, the middle section to articulation tests, and the lower section to non-language tests, with the strength of the association to the three disorders displayed.

The phi coefficient, which extends to the right on the graph, indicates a stronger correlation between the test item and the disorder. By observing the colors, you can visually confirm which disorder has the strongest correlation with each test item.

Focusing on the articulation tests in the middle section, you can see that the green bars extend further to the right than the orange or navy bars. Notably, the disease-specific response of Oral Diadochokinesis ③ (/ka/) is particularly significant.

This suggests that the STAD articulation test has strong validity in the assessment of dysarthria, with OraDiadocho ③ (/ka/) showing the most notable results.

When an SLP devises a speech therapy strategy for stroke patients, they should determine whether the patient has aphasia, dysarthria, or cognitive dysfunction.

The STAD articulation test provides evidence of its disease-specific response to dysarthria, allowing you to use it as a screening tool to differentiate the types of communication disorders.

This article explores the efficiency and validity of using the STAD (Screening Test for Aphasia & Dysarthria) for dysarthria detection, focusing on the oral diadochokinesis and oral movement tests. Developed in Japan and validated in large-scale studies, STAD offers a rapid, evidence-based method for speech-language pathologists (SLPs) to assess dysarthria.

Ultimately, the article aims to equip SLPs with the knowledge to detect dysarthria efficiently using STAD, offering a practical tool that combines speed and accuracy in diagnosis.