cooperative research. To discuss the relationship of apraxia of speech to stuttering is especially difficult because apraxia of speech is controversial and com-. A parent's grit and determination paves the road for their child's apraxia many children will go through dysfluency, which sounds similar to stuttering. . Instead, try to focus on your child's progress and the relationships they have formed. A Diagnostic Marker to Discriminate Childhood Apraxia of Speech From Speech .. Pearson r correlation coefficients for two indices and 18 signs of speech and levels of dysarthria, stuttering, cluttering, and velopharyngeal incompetence.
However, individual profiles revealed patterns of dissociation between the 2 in a few cases, with evidence of double dissociation of speech and oral apraxic impairment. We discuss the implications of these relationships for models of oral motor and speech control. Speech apraxiaOral apraxiaStrokeDissociationAssociation Introduction Apraxia of speech AOS is a motor speech disorder where the movement plans that control speech production are impaired or inaccessible.
As a consequence, speech output is characterized by a range of features that affect intelligibility. There is often evidence of initiation difficulties, and articulatory groping, which involves preparatory visible and sometimes audible speech movements and gestures. The temporal components of speech can be disrupted and features such as the voice onset time patterns of plosives can be disturbed e. Other temporal dimensions of speech are also affected, with output displaying longer intersyllabic pauses, prolonged segment and syllable durations e.
Furthermore, the spatiotemporal dimensions of speech are affected, and substitutions and distortions of articulatory targets are perceived as a result of misdirected gestures Bartle-Meyer et al. Controversies surrounding AOS also extend to its relationship with other forms of impairment resulting from left hemisphere LH injury such as aphasia and oral apraxia OA.
Verbal Dyspraxia and Stuttering Michelle Harmon Apraxia Stuttering
AOS is recognized on the basis of spatiotemporal disruptions of speech gestures that affect fluency and intelligibility. Both vegetative functions respiration, laryngeal and palatal valving, chewing, and swallowing and volitional nonspeech oral gestures, such as sticking out the tongue or performing lateral tongue movements to command, may be relatively normal. OA is diagnosed when, despite intact sensory motor function evident in vegetative use of the respiratory—oral tract, an individual is unable to use these effector systems under voluntary control.
OA like AOS and other movement apraxias typically occurs following LH damage, which suggests that crucial movement control systems are lateralized.
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Typical clinical assessment tasks for OA involve imitating nonspeech movements such as blowing, smiling, or licking the lips Bizzozero et al. A complicating factor in the identification of OA is that, as an impairment of volitional movement, evaluations require that a patient performs oral movements in response to spoken commands Dabul, Patients with significant comprehension failure due to coexisting aphasia may fail to understand commands and may be slow to perform movements or require a model before they can enact the movement.
This attracts a scoring penalty in standard clinical evaluations. As a result, an individual might be classed as displaying OA deficits when the source of the impairment lies elsewhere and the presence and degree of OA may be overdetermined by standard clinical evaluations.
However, these tasks are not widely available. Some patients with AOS appear to display a movement disorder that is restricted to speech e. The frequent co-occurrence of conditions might indicate that the control mechanisms for oromotor and speech motor control depend to some degree on shared substrates and resources Ballard et al.
Although gross oral movements such as moving the tongue from side to side remain relatively unimpaired in instances of limited damage, the finer and faster movements of speech, requiring narrowly targeted and tightly integrated gestures, are disrupted.
Evidence from functional neuroimaging also supports the proposal that neural networks underpinning speech and nonspeech behavior overlap to some degree New et al. The evidence of a double dissociation between conditions would suggest some degree of autonomy between speech and oromotor control Shallice, Proposals of independence between components of control systems for speech and nonspeech oral movement are consistent with approaches that view complex behaviors as being mediated by multiple assemblies of processing systems.
In the case of speech and nonspeech oral motor control, the total assemblies that mediate each form of behavior are likely to be rather different Weismer, The movement control system for speech will be closely interconnected with auditory and more general linguistic processing mechanisms.
Furthermore, speech movements in adults are entrained actions that have been executed many times.
In contrast, a request to produce an action such as moving the tongue alternately between the top and bottom lips is a novel action sequence. Different neural systems are recruited in executing novel as opposed to overlearned movements. Nonspeech oral movement is also likely to place greater dependence upon occipitoparietal somatosensory and visuospatial systems in targeting movements and determining whether visual targets have been reached.
Functional brain imaging studies support the proposal that the neural networks for speech motor control can be differentiated from those employed in nonspeech oral movement. In addition to difference in the total neuronal assembly for speech and nonspeech oral movements, there are also differences in the movement parameters of the two forms of action.
Differences in force, speed, and spatial targeting have been described Bunton, ; Weismer, ; Ziegler,suggesting that even within dedicated motor control mechanisms, there is potential for separation between the two forms of movement.
However, it is likely that movements of the vocal tract, whether they result in speech or nonspeech gestures, involve some common units, for example, at the level of primary motor cortex. Therefore, the degree of autonomy between speech and oromotor control will be constrained Ballard et al. In terms of patterns of association and dissociation that might occur between AOS and OA, a partial autonomy model is able to account for all possible patterns.
In this article, we evaluate the severity of speech and volitional nonspeech oral movement impairment in a large clinical sample of 50 participants with AOS. In addition to exploring relationships at group level, we conducted individual case profiling to determine if there was evidence of double dissociation of speech and oral apraxic impairment.
Given the theoretical importance of cases where OA impairment was disproportionate to degree of AOS, we examined the behavioral profiles of such cases to determine if their difficulty in performing oral movements to command could be attributed to impaired auditory comprehension.
Children with Apraxia & Stuttering
All participants gave their informed consent, but one participant later withdrew from the study. The remaining 50 participants were recruited to an intervention study Whiteside, Inglis, et al. These baseline profiles are the focus of the current article.
Brain imaging was not available for all participants. There was attested LH pathology for 38 participants. There was no information regarding lesion location for 11 participants, and one participant, who was right handed, showed signs of right hemisphere pathology.
All participants were assessed for handedness by asking them to report their hand preference in opening a jar, brushing teeth, throwing a ball, and writing and footedness kicking a ball. All participants except for six were either right or predominantly right-lateralized for handedness and footedness.
Of the six non-right handers, three displayed mixed laterality, and three were predominantly left handed. Two speech and language therapists independently identified the participants as having AOS using standard diagnostic criteria such as longer syllable durations, speech errors sound substitutions and sound [phonetic] distortionsreduced speech fluency, and dysprosody e. All participants had some degree of coexisting aphasia. Behavioral Profiling The extent of aphasic difficulties, the severity of AOS, and the presence of nonspeech oral impairment were assessed by raters who were blind to the purpose of the analysis.
All raters were qualified speech and language therapists who went through a process of consensus training. The details of the assessments are provided under three headings Severity of oromotor impairment, Severity of AOS, and Aphasia severity. Severity of oromotor impairment Volitional nonspeech movements to command The nonspeech oromotor assessments consisted of three tasks that involved subcomponents of the speech production system laryngeal, lingual, and labial.
In the laryngeal task, participants were instructed: The labial task involved alternate lip spreading and rounding. In all three subtasks, if no response was made after 10 s, a demonstration was provided. The scoring of the nonspeech oromotor tasks was based on the established system and assessment devised by Dabulwith a score of 5 for correct responses and 4.
InYoss and Darley suggested that stuttering as well as articulation difficulties might be expressions of developmental apraxia.
Whether or not Yoss' and Darley's suggestion is true, both stuttering and apraxia "have been defined or studied in terms of speech motor control dysfunction Neuroimaging techniques are beginning to give researchers new insights into sites of abnormality that were not previously available.
In developmental apraxia, Kent cites studies that found abnormalities in cortical and subcortical motor related areas of the frontal lobe. The studies also identified the basal nuclei, particularly the caudate nucleus, as being abnormally small.
Kent's review of the some of the neuroimaging research in individuals who stutter suggest that "stuttering can result from a variety of neurological disturbances and is not necessarily related to damage to any one structure or neural pathway".
One of the structures that has been implicated in stuttering is the basal nuclei. Most of us have witnessed the groping behaviors during the motor programming efforts of individuals with apraxia.
We have also seen groping posturing of the articulators in children who stutter as they try to "program" their speech. Blomgren and Nagarajan have observed, through neuroimaging, a reversal of cortical activation sequences during motor programming of individuals who stutter in that they initiate the motor program before preparing the articulatory code.
Most of us are also aware of the effortful nature of apraxic speech and of stuttering behaviors. It is possible that the tense behaviors of apraxic speech are classically conditioned or paired with normal dysfluent behaviors, which then develop into a stuttering disorder in the same fashion as classical conditioning may occur in individuals who stutter without apraxia. It is also possible that a version of Bloodstein's Communication Failure theory of stuttering may be operating in the child with apraxia, in that the child with apraxia experiences communication failure and talking difficulty.
This results in tension when talking. Since stuttering is a tension behavior, stuttering may develop as a result. Regardless of whether the stuttering is related to the dysapraxia or whether it is a separate concern, I would suggest that you primarily address the apraxia.
Verbal Dyspraxia and Stuttering
As you address it, you might consider attempting strategies designed to take the effort out of speaking and phonating. In addition, it is well known that both apraxia and stuttering respond well to rhythms and melodic types of strategies. These strategies might help you to manage the fluency difficulties as well. In fact, it is perfectly all right to work on fluency and articulation concurrently Ratner, Some sources that might assist you in treating your child include the following: Management strategies for developmental apraxia of speech: A review of literature.