L4 Apraxia Flashcards
what is apraxia of speech
“ an acquired disorder of learned volitional actions associated with breakdown in the planning or programming of the movements needed for speech” (Miller and Wambaugh, 2017, p. 493).
is AOS acquired or developmental
acquired
what movements does AOS affect
volitional movements not reflexive movements
does it AOS affect non speech movements
no, apraxia of non speech movements are oral apraxia or bucco-facial apraxia
who came up with kernal diagnostic features
(McNeil et al., 1997; 2004; 2009)
kernal diagnostic features
- Sound distortions (including distorted substitutions)
- Extended segment durations - segment meaning sound or syllable
- Extended intersegment durations - long pauses give a robotic quality
- Prosodic deficits - monotone, no intonation or melody, aids in robotic effect
segment
smallest unit of sound e.g. a consonant or syllable
substitutions
speaker has selected or accessed incorrect phonemes and articulated these normally (e.g in phonemic paraphasia)
distortions
the correct phoneme was accessed, but articulated in an imprecise or unusual way (e.g. in AOS, dysarthria)
distorted substitutions
the impression that both phoneme selection and articulatory accuracy are incorrect – most common error type in AOS
most common distortions in AOS
length, voicing, tongue placement
extended segment durations
lengthened production of consonants and vowels → rate of speech is perceived as slower overall
Extended intersegment durations
lengthened pauses between sounds and between words → speech sounds segmented
what is an intrusive schwa
the insertion of a shwa into a segment where there shouldn’t be one
prosodic deficits that occur in AOS
- restricted alteration of pitch, intonation, loudness – may sound monotonous
- Slow rate of speech is common – this may be due to increased segment and intersegment durations
- Equal lexical stress
- No longer sound like themselves/unnatural sounding
- Can very occasionally sound like a foreign accent
non-discriminatory features of AOS
- articulatory groping
- perserverative errors
- increasing errors with word length
- awareness of errors
- variability
what is articulatory groping
- Gives the impression that speaker is trying to find right position
- Can be silent or auditory
error location
whether an error occurs on the same target sound within a word across repeated trials
error type
whether the same error is made within the same location of a word across repeated trials
what is not a feature of AOS
discriminatory errors - may find this in old literature but no longer considered true
severity scale of AOS
Slightly slow, relatively fluent speech → slow segmented speech with lots of sounds errors and disturbed prosody → complete inability to speak
what happens if there is minimal or no speech output
It is difficult to reliably diagnose AOS in a client who has very little speech output, because this does not allow you to observe the core features of AOS. You might reach a tentative diagnosis of “probable” or “suspected” AOS but you may also need to consider other diagnoses such as aphasia. Being unable to produce any verbal output can also be caused by aphasia.
AOS and aphasia
co-occur very often
AOS and dysarthria
sometimes co-occur
pure AOS
very rare
Acute AOS
- Primarily caused by stroke – typically left hemisphere; most often frontal and parietal lobes; most often larger strokes
- Can also be caused by head injury (traumatic brain injury or TBI) or a brain tumour/brain surgery
when can AOS be caused by a right hemisphere stroke
when the person is left handed (dominant hemispheres switched)
when does primary progressive AOS (Josephs et al., 2006) occur
as the first sign of a progressive neuro-degenerative disease
what diseases can primary progressive AOS be a sign of
- Cortico-basilar degeneration (CBD)
- Progressive supranuclear palsy (PSP)
- Motor neurone disease(MND)/Amyotrophic lateral sclerosis (ALS)
which brain regions have been proposed as being assocaiated with AOS
- left insula
- Broca’s area/left inferior frontal gyrus
- Pre-central gyrus - primary motor area
- Post-central gyrus - primary somtosensory area
- Pre motor cortex
why is it hard to definitively say where AOS lesions occur
- speech is organised all over the brain
- stroke/TBI can damage more than one area of the brain
- organisation of the brain may change after injury due to neuroplacticity
what is a motor plan
- Brain tells articulators where to move, when to move and in what way to move
- Brain also tells articulators how fast to move, for how long and with how much force
four stages of van der merwe’s model of motor planning
- conceptual-linguistic stage
- motor planning stage
- motor programming
- execution
conceptual linguistic phase (van der merwe 1997)
- Pre-motor stage
- Intention to speak
- Message is constructed - syntax, semantics, morphology
- Phonological plan (phonemes)
motor planning stage (van der merwe 1997)
- Strategy of action
- Spatial specifications (place and manner of articulation)
- Temporal specifications (timing)
- Core motor plans are goals of movement
motor programming stage (van der merwe 1997)
- Muscle-specific programs selected and sequenced
- Spatial and temporal dimensions; tone direction, force and rate
execution stage (van der merwe 1997)
Articulators carry out the motor plan to form speech
which of the stages of van der merwe’s model of motor planning (1997) is affected by aphasia
conceptual linguistic
which of the stages of van der merwe’s model of motor planning (1997) is affected by AOS
motor planning
which of the stages of van der merwe’s model of motor planning (1997) is affected by dysarthria
execution
what does DIVA stand for
models of motor planning
Directions Into Velocities of Articulator
Explain DIVA model of motor planning
- This model suggests that we have a “speech sound map” believed to be located in the left frontal cortex
- This “map” area is believed to be made up of “mirror neurons” (Hickock, 2012) which are activated both when a sound is produced and heard
- These neurons are thought to be responsible for motor planning/programming by sending out “feedforward” commands to the articulators, and receiving “feedback” from auditory and sensory routes
theories to explain what goes wrong with motor planning in AOS (Miller and Wambaigh, 2017)
- The brain selects the incorrect motor programme (i.e. the opening or closing settings or sequences for the articulators) for the intended production target
- (e.g. selects the programme for /p/ when the target was /d/)
- The brain can no longer access stored programmes for the intended target, or the quality of these stored programmes has deteriorated
- There is interference in the brain between competing motor programmes
- (e.g., competition between the tongue tip and the dorsum raising in target /’take’/ → → may lead to what the listener hears as /‘cake’/
- The correct programme is selected, but the programme is applied to the wrong articulator
- (e.g., closing gesture applied to tongue dorsum instead of lips for the target /m/ would result in production of /ng/ instead)
explain feedforward and feedback in motor planning (ballard, tourville and robin, 2014)
- A movement goal is identified (e.g. producing a syllable)
- A motor program or command for that movement is activated and initiated
- Simultaneously an efference copy of that command is generated, i.e. a prediction of the expected sensory feedback from the issued motor command
- As the movement unfolds, the actual sensory consequences are compared to the prediction
- If a mismatch is detected, error signals arise and corrective motor commands are generated to modify the ongoing movement
- The error signals are also used to update the “stored” motor programs, thereby improving the accuracy of future attempts to perform that motor task → this is motor learning
