Coarticulation patterns in children with developmental apraxia of speech

The aim of this study was to enhance our insight into the underlying deficit in developmental apraxia of speech (DAS). In particular, the involvement of planning and/or programming of speech movements in context was tested by analysing coarticulatory cohesion. For this purpose, second formant frequency measurements were conducted in repetitions of nonsense utterances ([ CV]C=/s,x,b,d/; V=/i,a,u/), and compared across nine children with DAS, six normally speaking (NS) children and six adult women. The results showed both intra- and intersyllabic anticipatory coarticulation in NS children and adult women, in which the intersyllabic coarticulation was stronger in NS children than in adult women. The children with DAS showed more variability as compared to NS children, made, on average, less distinction between the vowels, and showed individually idiosyncratic coarticulation patterns. These results are discussed in the light of a delay as well as a deviance of speech development in children with DAS.     

A speech motor learning approach to treating apraxia of speech: Rationale and effects of intervention with an adult with acquired apraxia of speech

Background: In this paper the rationale for a treatment of apraxia of speech, the speech motor learning (SML) approach, is described and the effects of its application explored. The SML approach endeavours to address the underlying inability to plan and program the production of different speech motor targets (SMTs) in changing phonetic contexts and in utterances exceeding a single word/nonword in length.

Aims: The aims of the study were to determine (1) if treatment effects generalised to untreated nonwords and untreated real words with trained vowels and consonants, (2) if a learning effect was maintained, (3) if the treatment task hierarchy of the SML approach could be confirmed, and (4) if the number of speech errors judged perceptually declined across the treatment period on treated and untreated stages.

Methods & Procedures: A multiple baseline single-participant design across behaviours and contexts was used to assess the effects of treatment with a speaker with chronic pure AOS. The first six stages of an eleven-stage treatment hierarchy were consecutively treated. The last five remained untreated.

Outcomes & Results: During treatment, production of untrained nonwords and words containing trained and untrained SMTs improved. For three treated stages the improvement was greater during the treatment phase than during baseline, for words, nonwords, or both. Stage 4 vowels only improved once treatment commenced. Untreated consonant clusters of Stage 10 improved negligibly. Improvement was maintained 2 years post-treatment. The number of speech errors decreased across the treatment period.

Conclusions: Preliminary evidence is provided supporting a general improvement in speech motor planning and programming ability for this participant. The relative value of components of the SML approach needs to be verified in future.     

Treating apraxia of speech (AOS) with EMA-supplied visual augmented feedback

Background: Previous studies have suggested that visual augmented feedback provided by electromagnetic articulography (EMA) helps persons with apraxia of speech (AOS) recover speech motor control following stroke (e.g., Katz et al., 2007 Katz, W., Garst, D., Carter, G., McNeil, M., Fossett, T.Doyle, P. 2007. Treatment of an individual with aphasia and apraxia of speech using EMA visually augmented feedback. Brain and Language, 103: 213–214. [Crossref], [Web of Science ®] , [Google Scholar]). However, the data are few, both in terms of the variety of participants and the speech motor targets investigated.

Aims: This study was designed to determine whether EMA supplied feedback improves articulatory accuracy in an adult with acquired AOS. We also examined whether reduced feedback frequency results in (1) decreased performance during acquisition and (2) enhanced maintenance and generalisation of the targeted behaviours.

Methods & Procedures: A multiple-baseline across-behaviours design was used to assess the efficacy of this treatment for an individual with AOS. Over a 27-week period, the participant received visual feedback provided by an EMA system for treatment of three groups of speech motor targets (SMTs): /j/, /θ/, and /t∫ / with various following VCs. The consonant clusters /br/ and /sw/ served as untreated controls. Frequency of feedback scheduling was 100% for /j/ and /t∫?/, and 50% for /θ/.

Outcomes & Results: For the first group of SMTs treated, /j/, there was acquisition for 4/5 trained words. These were maintained post-treatment and at the long-term probe. Improved performance and maintenance were also noted for 5/8 untreated stimuli, with maintenance shown for most of these words by 1 month post-treatment. The next treated SMT, /θ/, showed acquisition for all five treated items. Two of these five targets were maintained one month post-treatment. All three untreated /θ/ probes showed generalisation, with two of these showing maintenance post-treatment. The third treated group of SMTs, /t∫/, showed improved performance for all of the five treated words. However, these gains could only be attributed to /t∫/ treatment for three of the five words. Two treated items appeared well maintained at 1 month post-treatment. Generalisation and maintenance were also noted for all six untreated /t∫?/ words. However, generalisation from previously treated /j/ and /t∫/ targets was involved in their improved performance. The untrained (control) word data suggested that the gains noted for treated items did not result from across-the-board improvement or unassisted recovery. There were no consistent differences corresponding with low- versus high-frequency feedback conditions.

Conclusions: Augmented kinematic feedback provided by an EMA system improved production for some, but not all, treated targets. Generalisation to untreated probes was also evident. Predictions concerning the effects of feedback frequency on the acquisition, maintenance, and transfer of trained behaviours were not supported.     

A kinematic investigation of anticipatory lingual movement in acquired apraxia of speech

Background: Apraxia of speech (AOS) is considered a disorder of speech planning or programming. Evidence for this stems from perceptual, acoustic, and electropalatographic investigations of articulation in AOS that revealed a delayed onset of anticipatory vowel gestures. Articulatory prolongation and syllable segregation have been attributed to a disturbance in anticipatory coarticulation.

Aims: The aim of the current study was to investigate anticipatory lingual movement for consonantal gestures in AOS, and its impact on absolute and relative speech timing.

Methods & Procedures: Tongue-tip movement and tongue-to-palate contact patterns were recorded for three speakers with AOS and a concomitant aphasia (age range?=?35–63 years; M?=?50.67 years; SD?=?14.29) and five healthy talkers (age range?=?29–65 years; M?=?52.6 years; SD?=?14.5) during the phrases “a scarlet” and “a sergeant”, using electromagnetic articulography (EMA) (AG-200 system) and electropalatography (EPG) (Reading Electropalatograph system). Anticipatory lingual movement and speech timing were analysed during the final C₁VC/C₂ syllable in each of these phrases, where C represented an alveolar or postalveolar consonant. Specifically, tongue-tip displacement was calculated from the onset of release to the end of release of C₁ to provide an indication of anticipatory lingual movement. With respect to speech timing, absolute (i.e., duration from time of maximum contact for C₁ to time of maximum contact for C₂) and relative (i.e., absolute duration expressed as a function of total syllable duration) durational measures were recorded, as was the stability of each. The results recorded for each of the participants with AOS were individually compared to those obtained by the control group.

Outcomes & Results: The EMA results indicated that two participants with AOS exhibited reduced anticipatory lingual movement (i.e., greater tongue-tip displacement) during repetitions of “sergeant”; however, all speakers produced a comparable tongue-tip displacement to that produced by the control group during the release of /l/ in “scarlet”. The EPG results indicated that absolute duration was significantly prolonged during the final syllables of both stimuli for each of the apraxic speakers. Equivocal results were reported for relative timing and temporal stability.

Conclusions: The results provide some preliminary evidence of reduced anticipatory lingual movement in AOS, and have demonstrated that this can have a significant impact on absolute speech timing. However, measures of relative timing were suggestive of either unimpaired or more extensive coarticulation. Additional research is required to resolve this issue.     

Prosody-voice characteristics of children and adults with apraxia of speech

We address explanatory issues raised by prior findings on the prosody-voice characteristics of suspected apraxia of speech in children (AOSc). Prosody-voice patterns for 14 adults with apraxia of speech (AOS) were compared to the prosody-voice patterns of 14 children with suspected apraxia of speech and inappropriate stress (AOSci) using the same assessment instruments and analysis methods. Compared to the speakers with AOSci, speakers with AOS had significantly fewer utterances meeting criteria for inappropriate stress, and significantly more utterances meeting criteria for inappropriate phrasing and inappropriate rate of speech. Discussion focuses on the implications of these three dissociations for the psycholinguistic locus of the stress deficit in AOSci including candidate loci within linguistic, motor speech, and self-monitoring processes.     

Lesion correlates of conversational speech production deficits

We assess brain areas involved in speech production using a recently developed lesion-symptom mapping method (voxel-based lesion-symptom mapping, VLSM) with 50 aphasic patients with left-hemisphere lesions. Conversational speech was collected through a standardized biographical interview, and used to determine mean length of utterance in morphemes (MLU), type token ratio (TTR) and overall tokens spoken for each patient. These metrics are used as indicators of grammatical complexity, semantic variation, and amount of speech, respectively. VLSM analysis revealed that damage to the anterior insula was predictive of low scores on MLU and tokens, consistent with prior findings of the role of this region in speech production [Dronkers, N. F. (1996). A new brain region for coordinating speech articulation. Nature, 384(6605), 159-161]. Additionally, the inferior frontal gyrus, sensorimotor and anterior temporal areas were also associated with lower scores on both of these measures. Overall, token and MLU maps were highly similar, suggesting an overlap between grammatical language networks and overall fluency. TTR maps also shared some portions of this network, but damage to posterior temporal regions also reduced scores on this measure. These results represent the first voxel-based lesion analysis of speech production performance in aphasic patients.     

Phonological encoding in apraxia of speech and aphasia

Background: Apraxia of speech (AOS) is considered a speech motor planning/programming disorder. While it is possible that co-occurring phonological impairments exist, the speech motor planning/programming deficit often makes it difficult to assess the phonological encoding stage directly. Studies using online methods have suggested that activation of phonological information may be protracted in AOS.

Aims: The present study was designed to investigate the integrity of the phonological encoding stage in AOS and aphasia. We tested two specific hypotheses, the Frame Hypothesis and the Segment Hypothesis. According to the Frame Hypothesis, speakers with AOS have an impairment in retrieving metrical frames (e.g., number of syllables); according to the Segment Hypothesis, speakers with AOS have an impairment in retrieving segments (e.g., consonants).

Methods & Procedures: Four individuals with AOS and varying degrees of aphasia, two speakers with aphasia, and 13 age-matched control speakers completed an online priming task in which participants name pictures in sets that do or do not share number of syllables (e.g., balcony-coconut-signature vs. balcony-carrot-sock), the initial consonant (e.g., carpenter-castle-cage vs. carpenter-beaver-sun), or both (e.g., boomerang-butterfly-bicycle vs. boomerang-sausage-cat). Error rates and reaction times were measured.

Outcomes & Results: Data for controls replicated previous literature. Reaction time data supported the Segment Hypothesis for speakers with AOS and for one speaker with aphasia without AOS, with no differences in pattern from controls for the other speaker with aphasia without AOS.

Conclusions: These results suggest that speakers with AOS may also have difficulties at the phonological encoding stage. Theoretical and clinical implications of these findings are discussed.     

Audio-visual matching of speech and non-speech oral gestures in patients with aphasia and apraxia of speech

BACKGROUND: Audio-visual speech perception mechanisms provide evidence for a supra-modal nature of phonological representations, and a link of these mechanisms to motor representations of speech has been postulated. This leads to the question if aphasic patients and patients with apraxia of speech are able to exploit the visual signal in speech perception and if implicit knowledge of audio-visual relationships is preserved in these patients. Moreover, it is unknown if the audio-visual processing of mouth movements has a specific organisation in the speech as compared to the non-speech domain. METHODS: A discrimination task with speech and non-speech stimuli was applied in four presentation modes: auditory, visual, bimodal and cross-modal. We investigated 14 healthy persons and 14 patients with aphasia and/or apraxia of speech. RESULTS: Patients made substantially more errors than normal subjects on both the speech and the non-speech stimuli, in all presentation modalities. Normal controls made only few errors on the speech stimuli, regardless of the presentation mode, but had a high between-subject variability in the cross-modal matching of non-speech stimuli. The patients' cross-modal processing of non-speech stimuli was mainly predicted by lower face apraxia scores, while their audio-visual matching of syllables was predicted by word repetition abilities and the presence of apraxia of speech. CONCLUSIONS: (1) Impaired speech perception in aphasia is located at a supra-modal representational level. (2) Audio-visual processing is different for speech and non-speech oral gestures. (3) Audio-visual matching abilities in patients with left-hemisphere lesions depend on their speech and non-speech motor abilities.     

Whole-exome sequencing supports genetic heterogeneity in childhood apraxia of speech

Background

Childhood apraxia of speech (CAS) is a rare, severe, persistent pediatric motor speech disorder with associated deficits in sensorimotor, cognitive, language, learning and affective processes. Among other neurogenetic origins, CAS is the disorder segregating with a mutation in FOXP2 in a widely studied, multigenerational London family. We report the first whole-exome sequencing (WES) findings from a cohort of 10 unrelated participants, ages 3 to 19 years, with well-characterized CAS.

Methods

As part of a larger study of children and youth with motor speech sound disorders, 32 participants were classified as positive for CAS on the basis of a behavioral classification marker using auditory-perceptual and acoustic methods that quantify the competence, precision and stability of a speaker’s speech, prosody and voice. WES of 10 randomly selected participants was completed using the Illumina Genome Analyzer IIx Sequencing System. Image analysis, base calling, demultiplexing, read mapping, and variant calling were performed using Illumina software. Software developed in-house was used for variant annotation, prioritization and interpretation to identify those variants likely to be deleterious to neurodevelopmental substrates of speech-language development.

Results

Among potentially deleterious variants, clinically reportable findings of interest occurred on a total of five chromosomes (Chr3, Chr6, Chr7, Chr9 and Chr17), which included six genes either strongly associated with CAS (FOXP1 and CNTNAP2) or associated with disorders with phenotypes overlapping CAS (ATP13A4, CNTNAP1, KIAA0319 and SETX). A total of 8 (80%) of the 10 participants had clinically reportable variants in one or two of the six genes, with variants in ATP13A4, KIAA0319 and CNTNAP2 being the most prevalent.

Conclusions

Similar to the results reported in emerging WES studies of other complex neurodevelopmental disorders, our findings from this first WES study of CAS are interpreted as support for heterogeneous genetic origins of this pediatric motor speech disorder with multiple genes, pathways and complex interactions. We also submit that our findings illustrate the potential use of WES for both gene identification and case-by-case clinical diagnostics in pediatric motor speech disorders.     

The uniqueness of speech among motor systems

This paper considers evidence that the speech muscles are unique in their genetic, developmental, functional and phenotypical properties. The literature was reviewed using PubMed, ScienceDirect, ComDisDome and other literature‐retrieval systems to identify studies reporting on the craniofacial and laryngeal muscles. Particular emphasis was given to studies of muscle fibre composition. A number of studies on mandibular, lingual, palatal and laryngeal muscles in humans show that these muscles are distinct from limb and other muscles. These speech‐related muscles typically contain diverse fibre types and these types can vary regionally within a muscle. In general, the muscles of the speech production system are designed for fast and/or variable contraction and fatigue resistance. The craniofacial and laryngeal muscles are unique among the muscle systems of the human body and the specialized properties of these muscles are relevant to understanding the biomechanics of speech and various speech disorders.     

Sequential processing deficit as a shared persisting biomarker in dyslexia and childhood apraxia of speech

The purpose of this study was to investigate the hypothesis that individuals with dyslexia and individuals with childhood apraxia of speech share an underlying persisting deficit in processing sequential information. Levels of impairment (sensory encoding, memory, retrieval, and motor planning/programming) were also investigated. Participants were 22 adults with dyslexia, 10 adults with a probable history of childhood apraxia of speech (phCAS), and 22 typical controls. All participants completed nonword repetition, multisyllabic real word repetition, and nonword decoding tasks. Using phonological process analysis, errors were classified as sequence or substitution errors. Adults with dyslexia and adults with phCAS showed evidence of persisting nonword repetition deficits. In all three tasks, the adults in the two disorder groups produced more errors of both classes than the controls, but disproportionally more sequencing than substitution errors during the nonword repetition task. During the real word repetition task, the phCAS produced the most sequencing errors, whereas during the nonword decoding task, the dyslexia group produced the most sequencing errors. Performance during multisyllabic motor speech tasks, relative to monosyllabic conditions, was correlated with the sequencing error component during nonword repetition. The results provide evidence for a shared persisting sequential processing deficit in the dyslexia and phCAS groups during linguistic and motor speech tasks. Evidence for impairments in sensory encoding, short-term memory, and motor planning/programming was found in both disorder groups. Future studies should investigate clinical applications regarding preventative and targeted interventions towards cross-modal treatment effects.     

Voice onset time in aphasia,apraxia of speech and dysarthria: a review

Voice onset time (VOT) is an objective temporal acoustic parameter defined as the time between the release of the oral constriction for plosive production and the onset of vocal fold vibrations. Many researchers consider VOT to be the most reliable acoustic cue for the distinction between voiced and voiceless stops. Previous studies have explored the physiological and linguistic factors underlying VOT production in normal speakers across several languages. A major clinical goal of acoustic analysis in speech disorder is to establish a correlation between the acoustic abnormalities and the phonetic perturbations. VOT could thus be used as an acoustic parameter that indicates the phonetic contrast between voiced and voiceless stops. This paper includes a critical review of the measurement of VOT, factors of VOT variability and the effect of neurogenic communication disorders on VOT. We review the VOT data from subjects who exhibit aphasia, apraxia of speech and dysarthria. These studies reveal that VOT perturbations in aphasia have been interpreted as phonemic or phonetic errors, while VOT abnormalities in apraxia of speech and dysarthria grossly reflect loss of motor control.     

Speech motor control in fluent and dysfluent speech production of an individual with apraxia of speech and Broca's aphasia

Apraxia of speech (AOS) is typically described as a motor‐speech disorder with clinically well‐defined symptoms, but without a clear understanding of the underlying problems in motor control. A number of studies have compared the speech of subjects with AOS to the fluent speech of controls, but only a few have included speech movement data and if so, this was primarily restricted to the study of single articulators. If AOS reflects a basic neuromotor dysfunction, this should somehow be evident in the production of both dysfluent and perceptually fluent speech. The current study compared motor control strategies for the production of perceptually fluent speech between a young woman with apraxia of speech (AOS) and Broca's aphasia and a group of age‐matched control speakers using concepts and tools from articulation‐based theories. In addition, to examine the potential role of specific movement variables on gestural coordination, a second part of this study involved a comparison of fluent and dysfluent speech samples from the speaker with AOS. Movement data from the lips, jaw and tongue were acquired using the AG‐100 EMMA system during the reiterated production of multisyllabic nonwords. The findings indicated that although in general kinematic parameters of fluent speech were similar in the subject with AOS and Broca's aphasia to those of the age‐matched controls, speech task‐related differences were observed in upper lip movements and lip coordination. The comparison between fluent and dysfluent speech characteristics suggested that fluent speech was achieved through the use of specific motor control strategies, highlighting the potential association between the stability of coordinative patterns and movement range, as described in Coordination Dynamics theory.     

Alternative organization of speech perception deficits in children

Children's first‐language perception base takes shape gradually from birth onwards. Empirical research has confirmed that children may continue to fall short of age‐based expectations in their speech perception. The purpose of this study was to assess the contribution of various perception processes in both reading and learning disabled children. A series of experiments was carried out with 450 Hungarian‐speaking schoolchildren: learning disabled, reading disabled and typically developing control first‐, second‐, and third‐graders. Data from seven perception tasks—focusing on acoustic, phonetic and phonological perception processes—were analysed. Results revealed that (i) there is no linear development in all groups across ages, (ii) correct performance is characteristic of both the perception process and the type of disability, and (iii) a specific pattern of organization can be drawn up as a factor in development.     

Temporal control in the voicing contrast: Evidence from surgery-related apraxia of speech

ABSTRACT

The goal of this study was to investigate the phonetic realisation of the voicing feature in two tumour resection-related Spanish speakers with apraxia of speech. Temporal parameters related to the phonological contrast of voicing in Spanish have been analysed for intervocalic voiced and voiceless obstruents embedded in isolated words and nonwords, and compared with data collected from healthy speakers. Results indicate that in devoiced productions, where VOT values fitted the ‘voiceless stops’ category, vowel duration values matched those of voiced stops and suggested the preservation of contextual voicing cues. An attempt at preserving a consonant/vowel duration ratio consistent with aerodynamic predictions for voicing contrast has been observed in apraxic correct production as well as in devoicing errors, but not in the control group, which could be interpreted as a compensatory mechanism.     

Treating control of voicing in apraxia of speech with variable practice

Background: Apraxia of speech (AOS) is generally considered a phonetic‐motoric disorder. As such, it is reasonable to draw on the motor learning literature to develop interventions for improving articulation. The often cited problem of impaired voicing control is used to test the application of a variable practice approach to training skilled movements in AOS. It is predicted that variable practice—practising a behaviour over a range of possible values or contexts—increases accuracy and stability of a trained behaviour.

Aims: The aims of the study were to test the influence of variable practice conditions on acquisition and long‐term maintenance of voiced and voiceless phonemes in words at the phrase/sentence level as well as on generalisation of treatment effects to phonemes of same and different manner. The protocol was tested on two individuals with moderate AOS, one of whom exhibited a concomitant moderate aphasia.

Methods & Procedures: A single subject multiple baseline across‐subjects design was used to examine efficacy of treatment for improving control of voicing for three fricative/affricate phonemes (Participant 1) or three plosive phonemes (Participant 2). The training sets included two voiced phonemes and one voiceless phoneme, each presented in the initial position of 10 different words. This provided a range of voice onset times and a range of phonetic contexts for each target phoneme, thus providing the variable practice. The inclusion of a voiceless phoneme that was produced at a high level of accuracy during baseline was hypothesised to reduce the chance of overgeneralisation from voiced to voiceless phoneme production.

Outcomes & Results: Consistent with predictions, participants demonstrated improved production of trained voiced phonemes and generalisation of treatment effects to untrained phonemes of same manner only. These effects were maintained up to 3 months post‐treatment. Results support training multiple fricatives or plosives in parallel in a variety of phonetic contexts (i.e., variable practice) as well as including a combination of voiced and voiceless phonemes in treatment to ensure maintenance of accurate voiceless phoneme production.

Conclusions: Results from two participants, varying in overall communication impairment severity, provide promising evidence that a variable practice approach to retraining speech behaviours in AOS is effective. Specifically, this approach resulted in long‐term maintenance of treatment effects and generalisation of treatment effects to untrained phonemes within manner class. Just as importantly, it did not result in overgeneralisation of voicing to voiceless phonemes. Further testing is required before recommending general clinical application.     

Negative motor seizure arising from the negative motor area: Is it ictal apraxia?

Purpose:   Seizure manifesting motor arrest, that is, negative motor seizure (NMS), is a rare epileptic condition in which only inability to conduct voluntary movements or praxis is produced, although consciousness is preserved. The negative motor area (NMA) seems to be responsible, but its generator mechanism has not yet been clarified.
Patients and Methods:   Three patients manifesting NMS were investigated. Two patients (ages 33 and 17) with intractable frontal lobe epilepsy had subdural grid implantation for epilepsy surgery, and one (age 77) had scalp electroencephalography (EEG) monitoring.
Results:   Ictal semiologies commonly observed, at least in the two patients, were found as follows; (1) indescribable or ill-localized aura, (2) repetitive involuntary vocalization, (3) inability to speak, (4) inability to move the extremities, and (5) subsequent evolution to positive motor seizures. Awareness and comprehension were preserved throughout the episode before generalized seizures. In two patients with epicortical EEG recording, ictal activity arose from the lateral NMA in one, and from the rostral supplementary motor area in the other. Cortical stimulation at NMA in one patient elicited symptoms identical to NMS. Another patient had scalp EEG and magnetic resonance imaging (MRI) abnormality, both suggesting the epileptogenic focus in the mesial frontal area.
Conclusion:   We showed that (1) NMS was a rare condition in patients with seizure focus in the frontal lobe, and (2) that the NMA was responsible for the symptoms. The documented state in the present study may reflect ictal apraxia, but it requires further investigation.     

A new MAPT deletion in a case of speech apraxia leading to corticobasal syndrome

Speech apraxia is a disorder of speech motor planning/programming leading to slow rate, articulatory distortion, and distorted sound substitutions. We describe the clinical profile evolution of a patient presenting with slowly progressive isolated speech apraxia that eventually led to the diagnosis of corticobasal syndrome (CBS), supporting the evidence that this rare speech disorder can be the first presentation of CBS. Moreover, we found a novel variant in MAPT gene, which is hypothesized to be disease-causing mutation. These results underscore the importance of genetic analysis – particularly in selected atypical cases – for in vivo understanding of possible pathophysiological disease process.