Apraxia of Speech: Causes, Symptoms, and Evidence-Based Treatment

Apraxia of speech is a motor planning disorder. A person with apraxia knows exactly what they want to say — the language is intact — but the brain cannot consistently translate that intention into the precise, coordinated sequence of movements the mouth, tongue, and jaw need to make. The result is effortful, inconsistent speech with frequent sound errors that vary from attempt to attempt.

The defining feature of apraxia is inconsistency. A person with aphasia has difficulty retrieving or formulating a word. A person with apraxia may produce the word correctly on one attempt, then stumble on it completely on the next. This variability is a product of failed motor programming, not linguistic failure.

Other characteristic features include:

• •Groping or trial-and-error searching movements of the lips and tongue before or during speech
• •Errors that are predominantly sound substitutions and transpositions rather than omissions
• •More errors on longer, less familiar words
• •Better performance on automatic speech (counting, singing, social phrases) than in deliberate, volitional speech
• •Awareness of errors — the person often knows immediately that what they said was wrong

Acquired apraxia of speech in adults is most commonly caused by stroke in the left hemisphere, particularly the anterior superior region including Broca's area and the premotor cortex. Damage disrupts the stored motor programs the brain uses to produce familiar words and sounds.

Less commonly, apraxia results from traumatic brain injury, brain tumours, or neurodegenerative conditions. A progressive form — primary progressive apraxia of speech — has been increasingly recognised as a distinct syndrome associated with frontotemporal degeneration.

Dysarthria is a motor execution disorder: the neural signals that control the speech muscles are weak, slow, or incoordinated. Dysarthric speech is typically consistent — the person makes the same types of errors at the same points, reflecting underlying muscle weakness.

Apraxia is a motor programming disorder: the signals themselves are the problem. Apraxic errors are inconsistent and groping. Many stroke survivors have both conditions simultaneously.

All effective apraxia treatments share a foundation in motor learning: high numbers of practice trials, immediate feedback, and systematic progression from simple to complex stimuli. Treatment intensity (total practice repetitions) predicts outcome more strongly than the specific technique used.

Melodic Intonation Therapy uses singing and rhythmic hand-tapping to leverage preserved right-hemisphere processing of melody. By intoning phrases to a simple melodic pattern while tapping the rhythm, many people with severe apraxia can produce utterances they cannot produce in ordinary speech.

SPT systematically trains the production of specific sounds through modelling, repetition, and a structured cueing hierarchy. The therapist models target sounds, the patient imitates, and feedback guides successive attempts.

VAST uses video modelling — a clearly visible face producing the target sound or word — to support imitation practice. The visual information supplements the auditory model and helps guide the patient's motor planning.

Motor learning requires repetition volume that a clinic schedule cannot deliver alone. A person practising 30 repetitions twice a week accumulates approximately 3,000 trials over a year. Adding 15 minutes of daily structured home practice can add 30,000 or more additional trials over the same period — a difference that directly translates to rate of improvement. See our aphasia home practice guide for how to structure daily sessions effectively.

For clinicians, ReSpeak's apraxia modules support structured repetition practice that patients complete between sessions, with session recordings available for clinical review before the next appointment.

• •ASHA — Acquired Apraxia of Speech
• •Tactus Therapy — MIT guide
• •NIDCD — Aphasia and related disorders