Apraxia of Speech

Acquired Apraxia of Speech (AOS) Overview

Part I: Background

What is Acquired Apraxia of Speech?

• Apraxia is a motor disorder resulting from neurological damage. It is characterized by the inability to execute purposeful movements despite having normal muscle tone and coordination. 

How does Acquired Apraxia of Speech occur? 

• AOS occurs when the part of the brain that controls coordinated muscle movement is damaged. This most often occurs in the left hemisphere of the brain. It can be caused by head injury, brain tumors, dementia, stroke, or other progressive neurological disorders.

Speech characteristics of AOS: 

• The speech production of those with AOS is often very effortful and overtly characterized by a great deal of struggle and frustration. Those with Apraxia of Speech have a high level of awareness of their speech errors. 
• Articulation errors
  • Note: Often inconsistent and include various sound-level errors such as phoneme substitutions and/or distortions, and voice-onset errors. For example, someone might produce very different error patterns on repeated attempts of the same word. 
• Limited Prosody
  • Note: The prosody of those with Apraxia of Speech is usually highly affected by the decreased rate of speech they adopt to avoid errors and fluency of speech is often disrupted by repeated attempts at self-repair. 
• Slowed Rate 
• Visible groping of the tongue, lips and mandible
  • Note: Oral groping is often displayed by an obvious trial-and-error behavior as the patient attempts to position their articulators in the correct position for speech. 

*Most of the time, resonance, coordination of respiration for speech and phonation are left intact. 

AOS can range from mild to severe: 

• Mild case:
  • Barely noticeable articulation errors 
• Moderate case:
  • Individual may continually struggle to articulate properly 
• Severe case:
  • Patient may produce only a handful of words appropriately and will exhibit extreme difficulty with producing appropriate speech 
• Profound case:
  • Renders a patient completely mute with the inability to produce even a single phoneme

Differential Diagnosis of Acquired Apraxia of Speech

Characteristic	AOS?	Dysarthria?	Aphasia?
Muscle Weakness	No	Yes	No
Articulatory Deficits	Yes	Yes	No
Prosodic Deficits	Yes	Yes	No
Language Processing Difficulties	No	No	Yes
Consistent Error Patterns	No	Yes	No
Groping for articulatory postures	Yes	No	No

Part II: Evaluation

Motor Speech Evaluation: 

• Purpose: to determine a Motor speech disorder and the severity

Components of a Motor-Speech evaluation: 

• Case History taken from medical records and patient/caregiver interview 
• Oral motor evaluation with maximum performance tasks
  • Purpose: This is when the therapist will ask the client to move their tongue, lips and mandible so that the basic function of these structures and their general appearance of the oral cavity can be evaluated. 
• Speech tasks that assess error patterns in speech
• Identification of confirmatory signs to support hypothesized motor speech diagnoses 

Step 1: Case History

• Thorough review of available medical records and background 
• Interview of patient and caregivers
  • Ask questions that explore the nature of the illness or pathology producing speech problems as well as the perceived impact that speech deficits have on the communication abilities and the patient’s state of mind 
  • Observe the patient’s speech in a natural context 

Step 2: Oral Motor Evaluation 

• Facial symmetry at Rest: Observe Facial Symmetry- Eyes, lips, cheeks (assess symmetry)
• Evaluation of Labial movement:
  • Ask Patient to Pucker (assess strength, deviation, range of motion)
  • Ask client to pucker against mild resistance of a tongue depressor (assess strength)
  • Ask patient to smile (assess symmetry, deviation)
  • Ask patient to close lips and inflate cheeks to test labial seal (assess strength, air leakage)
• Evaluation of Mandible:
  • Ask Patient to open their mouth (assess symmetry, deviation, range of motion)
  • Ask patient to move their mandible from side to side (assess range of motion)
  • Ask client to lower mandible against moderate resistance of your gloved hand (assess strength)
  • Ask patient to raise mandible against mild resistance of your gloved hand holding chin down (assess strength)
• Evaluation of Dentition:
  • Teeth: (present, absent, dentures)
  • Dental hygiene
  • Occlusion
• Evaluation of the tongue:
  • Observe tongue at rest (assess color, appearance, movements)
  • Ask patient to protrude the tongue (assess movement, symmetry, deviation)
  • Ask patient to protrude the tongue and move tongue as far left and as far right as possible (assess range of motion)
  • Ask patient to push left and then right against a tongue depressor with extended tongue (assess strength)
  • Ask patient to push tongue against inside of left and right cheeks against resistance of your gloved hand (assess strength)
• Evaluation of Hard Palate- Color, Palatal arch
  • Note abnormalities: Fistula/Cleft, etc. 
• Evaluation of Velum (Soft Palate)/Pharynx:
  • Observe Velum (assess symmetry, deviation, color, movements)
  • Observe Tonsils (removal, appearance)
• Laryngeal Evaluation:
  • Ask patient to cough as hard as they can (strength, wet/dry, Hypo/Hyperadduction)
  • Ask patient to sustain /a/ for as long as possible (more or less than 20 seconds)
• Speech and Speech-like tasks:
  • Sequential and alternating motion rates:
    • Have the client produce: 
      • PUH
      • TUH 
      • KUH 
      • PUH TUH 
      • TUH KUH 
      • PUH KUH 
      • PUH TUH KUH 
  • Spontaneous Speech sample:
    • Observe the patient’s speech during the speech interview (assess resonance, Pitch/Loudness of voice)

Step 3: Speech tasks that assess error patterns in speech

After the structures and functions of the articulators and speech systems have been examined in isolation using nonspeech tasks, it is then useful to observe how the patient performs when asked to coordinate these structures and functions to produce speech. 

Step 4:  Identification of confirmatory signs to support hypothesized motor speech diagnoses 

Look for observable physiologic characteristics displayed by the  individual that support the therapist’s diagnosis. This can range from the presence of abnormal muscle tone (flaccid or spastic), to patterns of paresis/paralysis, to the presence of abnormal reflexes or involuntary movements. Take note. 

Part III: Treatment

*Behavioral Treatment is the most effective in treating AOS (Duffy, 2013)

Treatment for Mild AOS:

• Eight step continuum treatment 
• Contrastive Stress Drills
• Speech Motor Learning treatment

Treatment for Moderate AOS:

• Contrastive Stress Drills
• Melodic Intonation Therapy (MIT)
• Eight step continuum treatment
• Script Training
• Speech Motor Learning treatment

Treatment for Severe/Profound AOS: 

• Total communication 
• Script Training
• Melodic Intonation Therapy (MIT) 
• Multiple Input Phoneme Therapy