Aphasia vs dysarthria vs apraxia of speech: How do you tell the difference? After all, an adult patient can have more than one at the same time, and the diagnoses can present similarly.
In this post, you’ll find a guide to differential diagnosis, including checklists, a quick screen, and a free Differential Diagnosis Chart PDF!
For everything you need to assess, treat, and document, check out our bestselling Adult Speech Therapy Starter Pack!
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What are Aphasia, Dysarthria, and Apraxia?
The following are patient-friendly definitions.
What is Apraxia of Speech?
Apraxia is a speech disorder caused by damage to the part of the brain that coordinates the movements of speech. A person with apraxia has difficulty coordinating what they want to say clearly and consistently.
What is Dysarthria?
Dysarthria is a speech disorder caused by weakness of the muscles that help us speak. This weakness comes from an underlying neurological disorder (stroke, ALS, Parkinson’s Disease, etc.) Speech may sound unclear, mumbled or slurred.
What is Aphasia?
Aphasia is a language disorder caused by brain damage that can result in difficulty understanding language, producing language, reading, and/or writing.
Differential Diagnosis Printable Chart (PDF)
Use the Differential Diagnosis chart as a checklist when making your diagnosis. If you’re in a hurry, download the free PDF and be on your way!
Keep scrolling for more differential diagnosis comparison charts and checklists.
Differential Diagnosis Chart
| Yes/No | Characteristic | Apraxia | Dysarthria | Aphasia |
|---|---|---|---|---|
| Distorted sound substitutions & additions (not including intrusive schwa “uh”) | ✓ | – | – | |
| Inaccurate speech AMRs (“puhpuhpuh”) | ✓ | – | – | |
| Speech SMRs (“puhtuhkuh”) more difficult than AMRs (“puhpuhpuh”) | ✓ | – | ✓ | |
| Increased sound distortions or distorted sound substitutions with increased speech rate, utterance length, and/or complexity | ✓ | – | – | |
| Reduced words per breath group relative to maximum vowel duration | ✓ | – | – | |
| Muscle weakness | – | ✓ | – | |
| Respiration affected | – | ✓ | – | |
| Phonation affected | – | ✓ | – | |
| Resonance affected | – | ✓ | – | |
| Voice changes | – | ✓ | – | |
| Language processing deficits | – | – | ✓ | |
| Reading and/or writing abilities affected | – | – | ✓ | |
| Articulatory deficits | ✓ | ✓ | – | |
| Prosodic deficits | ✓ | ✓ | – | |
| Sound distortions | ✓ | ✓ | – | |
| Slow overall speech rate | ✓ | ✓ | – | |
| Lengthened intersegment durations | ✓ | ✓ | – | |
| Lengthened vowel and/or consonant segments | ✓ | ✓ | – | |
| Syllable segmentation within words > 1 syllable | ✓ | ✓ | – | |
| Syllable segmentation across words in phrases/sentences | ✓ | ✓ | – | |
| Articulatory groping | ✓ | – | – | |
| Inconsistent errors | ✓ | – | ✓ | |
| Sound/syllable repetitions | ✓ | ✓ | ✓ | |
| Sound prolongations | ✓ | ✓ | ✓ |
Interpreting The Chart
Here are the main takeaways from the Differential Diagnosis Chart.
1. Your patient may have APRAXIA if:
- Their sound substitution or additions are distorted
- Saying “puhpuhpuh” was inaccurate
- Saying “puhtuhkuh” was even more challenging than “puhpuhpuh”
- There were more distortions the longer the word/utterance or the faster they spoke
2. Your patient may have DYSARTHRIA if:
- Their articulators seem weak (slurred or mumbled speech, etc)
- Respiration is abnormal (they seem out of breath, only get a few words in per breath, etc.)
- Phonation is abnormal (they seem quiet, etc)
- Voice or resonance are abnormal
3. Your patient may have APHASIA if:
- They seem to have a hard time understanding you
- They have difficulty reading
- They have difficulty writing
Quick Screen for Aphasia vs Dysarthria vs Apraxia
Here are five tasks to screen for aphasia, dysarthria, and apraxia. But be sure to also complete a full assessment, as this screen is limited.
See our Evaluation Pack for print-and-go adult speech therapy assessments!
- Engage in conversational speech
- Any difficulty following the conversation in their preferred language (aphasia)?
- Any sound distortions (apraxia, or dysarthria if due to weakness)?
- Any slurred speech or other apparent weakness (dysarthria)?
- Any apparent voice or resonance issues?
- Complete maximum phonation time
- Was it below normal limits (dysarthria)?
- Was it below normal limits (dysarthria)?
- Complete s/z ratio
- Was it outside normal limits (dysarthria)?
- Was it outside normal limits (dysarthria)?
- Ask them to read phrases (in their head) and fill in the blanks (aphasia)
- Ask them to write/copy short phrases (aphasia)
What If I’m Not Sure?
What do you do if you’re not sure what the right diagnosis is?
It’s easy to get tunnel vision when diagnosing a patient. We get it, you want to be accurate so that your goals make sense.
This is a great time to zoom out and remember why you’re seeing the patient in the first place. You’re helping them become more independent and safe to improve their quality of life. To get them there, you help improve their communication.
Pause, zoom out, and ask, “How can I help my patient communicate more fully right now?” Then write goals from that viewpoint.
For example, “The patient will [BLANK] in order to communicate basic wants and needs.” Then complete whatever evals you need in order to fill in the blank.
The answer may be “repeat multisyllabic words at 80% accuracy.”
Or “speak at the phrase level at 90% intelligibility.”
Or “generate 3-5 word sentences at 80% accuracy.”
Sometimes, starting at the end goal (improved communication, independence, and quality of life!) and working backward can make diagnosing feel less complicated.
Dysarthria vs Aphasia
How do you tell the difference between dysarthria and aphasia? See the checklist below for guidance.
| Yes/No | Characteristic | Dysarthria | Aphasia |
|---|---|---|---|
| Muscle weakness | ✓ | – | |
| Articulatory deficits | ✓ | – | |
| Prosodic deficits | ✓ | – | |
| Sound distortions | ✓ | – | |
| Slow overall speech rate | ✓ | – | |
| Lengthened intersegment durations | ✓ | – | |
| Lengthened vowel and/or consonant segments | ✓ | – | |
| Language processing deficits | – | ✓ | |
| Inconsistent errors | – | ✓ | |
| Reading and/or writing abilities affected | – | ✓ | |
| Sound/syllable repetitions | ✓ | ✓ | |
| Sound prolongations | ✓ | ✓ |
Apraxia vs Aphasia
How do you tell the difference between acquired apraxia of speech and aphasia? Here’s a checklist comparing the two, plus the Apraxia of Speech Rating Scale PDF.
| Yes/No | Characteristic | Apraxia | Aphasia |
|---|---|---|---|
| Articulatory deficits | ✓ | – | |
| Prosodic deficits | ✓ | – | |
| Articulatory groping | ✓ | – | |
| Slow overall speech rate | ✓ | – | |
| Sound distortions | ✓ | – | |
| Inaccurate speech AMRs | ✓ | – | |
| Syllable segmentation within words > 1 syllable | ✓ | – | |
| Syllable segmentation across words in phrases/sentences | ✓ | – | |
| Lengthened intersegment durations | ✓ | – | |
| Lengthened vowel and/or consonant segments | ✓ | – | |
| Language processing deficits | – | ✓ | |
| Reading and/or writing abilities affected | – | ✓ | |
| Sound/syllable repetitions | ✓ | ✓ | |
| Sound prolongations | ✓ | ✓ |
Apraxia of Speech Rating Scale (ASRS)
The Apraxia of Speech Rating Scale (ASRS) is the gold standard for evidence-based differential diagnosis of acquired apraxia of speech.
Duffy et al. include the ASRS in their research article. Scroll down to the appendix.
Apraxia vs Dysarthria
How do you tell the difference between acquired apraxia of speech and dysarthria? See the checklist below.
| Yes/No | Characteristic | Apraxia | Dysarthria |
|---|---|---|---|
| Articulatory groping, false starts/restarts, speech initiation difficulty | ✓ | – | |
| Inaccurate speech AMRs | ✓ | – | |
| Speech SMRs more difficult than AMRs | ✓ | – | |
| Distorted sound substitutions & additions | ✓ | – | |
| Errors increase with increased speech rate, utterance length, and/or complexity | ✓ | – | |
| Reduced words per breath group relative to maximum vowel duration | ✓ | – | |
| Muscle weakness | – | ✓ | |
| Consistent error patterns | – | ✓ | |
| Respiration affected | – | ✓ | |
| Phonation affected | – | ✓ | |
| Resonance affected | – | ✓ | |
| Voice changes | – | ✓ | |
| Sound/syllable repetitions | ✓ | ✓ | |
| Sound prolongations | ✓ | ✓ |
Speech Therapy Materials
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References
Allison KM, Cordella C, Iuzzini-Seigel J, Green JR. Differential Diagnosis of Apraxia of Speech in Children and Adults: A Scoping Review. J Speech Lang Hear Res. 2020 Sep 15;63(9):2952-2994. doi: 10.1044/2020_JSLHR-20-00061. Epub 2020 Aug 12.
American Speech-Language-Hearing Association. (n.d.). Acquired Apraxia of Speech. (Practice Portal). Retrieved June, 23, 2022, from www.asha.org/practice-portal/clinical-topics/acquired-apraxia-of-speech/
Brewer, C.H. (2019). The Home Health SLP Handbook (M. Aparo, Ed.). Harmony Road Design, LLC.
Strand, E. A., Duffy, J. R., Clark, H. M., & Josephs, K. (2014). The Apraxia of Speech Rating Scale: a tool for diagnosis and description of apraxia of speech. Journal of communication disorders, 51, 43–50. https://doi.org/10.1016/j.jcomdis.2014.06.008