Motor Speech Disorders on the Praxis SLP: Dysarthrias and Apraxia

Motor speech disorders are a guaranteed Praxis 5331 topic — and they're where many candidates lose easy points by confusing dysarthria subtypes with apraxia of speech. Once you know the lesion-to-symptom map, these questions become almost mechanical. Here is the focused review the exam actually rewards.

The two big buckets

• Dysarthria — a neuromuscular execution problem. Weakness, slowness, incoordination, or abnormal tone affecting the muscles of speech. Errors are consistent and predictable.
• Apraxia of Speech (AOS) — a motor planning/programmingproblem. Muscles work fine in isolation, but the brain can't sequence them for volitional speech. Errors are inconsistent, with groping and trial-and-error.

The seven dysarthrias (Mayo Clinic classification)

Apraxia of Speech — the 4 cardinal features

Per ASHA's adult AOS criteria, look for:

1. Slow overall rate, especially with lengthened segments and intersegment intervals.
2. Distorted sound substitutions and additions (not the clean substitutions you see in phonological errors).
3. Abnormal prosody — equal stress across syllables, segmented speech.
4. Trial-and-error groping with attempts at self-correction; errors are inconsistent on repeated productions of the same word.

Lesion: typically left frontal (insula, Broca's area, premotor cortex). AOS commonly co-occurs with Broca's aphasia — see our aphasia subtypes guide for the differential.

Childhood Apraxia of Speech (CAS) — exam-relevant points

• Three ASHA consensus features: inconsistent errors on consonants and vowels in repeated productions, lengthened/disrupted coarticulatory transitions, and inappropriate prosody.
• Not a delay. CAS is a motor planning disorder, not a phonological delay. Treatment is intensive and motor-based (DTTC, ReST, integral stimulation), not traditional articulation drill.
• Principles of motor learning matter. High repetitions, blocked early then random practice, immediate then faded feedback.

Evidence-based interventions to recognize

• LSVT LOUD — for hypokinetic dysarthria in Parkinson's disease. Single target: increased vocal loudness. Intensive: 16 sessions in 4 weeks.
• SpeechVive / EMST — respiratory-phonatory training for Parkinson's and other neurogenic populations.
• DTTC (Dynamic Temporal and Tactile Cueing) — gold-standard motor treatment for severe CAS.
• ReST (Rapid Syllable Transition Training) — for older children with CAS; targets prosody and transitions.
• Sound Production Treatment (SPT) — for adult AOS; hierarchical articulatory cueing.
• AAC — appropriate at any stage for ALS, severe progressive dysarthria, or unintelligible AOS. Don't wait until speech is gone.

The differential the exam keeps testing

• Dysarthria vs. AOS — dysarthria errors are consistent and distortions dominate; AOS errors are inconsistent with groping. Automatic speech (counting, social phrases) is often relatively preserved in AOS.
• AOS vs. phonological disorder — AOS shows groping and motor inconsistency; phonological errors are systematic substitutions following predictable patterns.
• Hypokinetic vs. spastic — Parkinson's = soft, monotone, fast; spastic = strained-strangled, harsh, slow.

Pair this with our cranial nerves guide (because almost every flaccid dysarthria question is really a cranial nerve question) and the content area breakdown to plan your adult-neuro week.