Apraxia of speech: how reliable are speech and language therapists' diagnoses?

Mumby, Katharyn; Bowen, Audrey; Hesketh, Anne

doi:10.1177/0269215507077285

Cited by 25 publications

(17 citation statements)

References 17 publications

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“…Specifically, we identified regions in cortical motor and somatosensory areas that predict AOS errors, even after removing variability explained by errors that could also occur in aphasia (and vice versa). The study of AOS has been built on different definitions of the disorder, 39–41 complicating the interpretation of findings regarding its localization and theoretical bases, and hindering the generalizability of conclusions pertaining to speech motor planning in general. On the most fundamental level, the current practices for AOS diagnosis are largely ambiguous and subject to variability in interpretation.…”

Section: Discussionmentioning

confidence: 99%

Patterns of Poststroke Brain Damage That Predict Speech Production Errors in Apraxia of Speech and Aphasia Dissociate

Basilakos

Rorden

Bonilha

et al. 2015

Stroke

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A praxia of speech (AOS) is a disorder of motor speech planning that can occur after brain damage to the language-dominant hemisphere. Generally, agreed on characteristics of AOS include articulatory imprecision, atypical prosody, frequent errors with consonants when compared with vowels, and distinct from speech production deficits that occur in aphasia and dysarthria, distorted sound additions and substitutions.1,2 The nature of these behaviors differs from that of aphasia, as AOS is neither a linguistic impairment (ie, a problem with the conceptualization of verbal symbols used to communicate thoughts) nor a problem with speech motor execution (ie, dysarthria). Rather, it is a deficit in planning speech motor movements. The study of AOS has been plagued by controversy since its description by Darley in 1968. 4,5 This can be attributed to the fact that the behavioral presentation of AOS is often difficult to distinguish from the speech production deficits that can occur in aphasia and dysarthria, [6][7][8][9] and because the anatomy of brain damage leading to AOS is similar to the pattern of damage leading to aphasia.10,11 A seminal study by Dronkers 12 in 1996 localized AOS to damage to the left insula, specifically the superior precentral gyrus of the insula (SPGI). Twentyfive poststroke patients with chronic AOS had SPGI damage, whereas patients without AOS did not have a lesion in this area. This double dissociation between SPGI damage and AOS has been argued as strong support for the role of the insula in AOS. 6,12,13 However, in the study by Dronkers, 12 none of the patients in the group without AOS were reported to have Broca aphasia or other speech impairment (eg, dysarthria). These patients were classified with Wernicke, anomic, conduction, or unclassifiable/no aphasia. In addition, lesion distribution maps for this group indicate that areas of maximal overlap occurred in posterior perisylvian areas; therefore, it can be argued that the lesion distribution of this group is too different to serve as an adequate comparison. 14 Furthermore, mounting evidence does not support the role of the insula in speech production generally 15 and AOS specifically, as such work has found that AOS can occur in the Background and Purpose-Acquired apraxia of speech (AOS) is a motor speech disorder caused by brain damage. AOS often co-occurs with aphasia, a language disorder in which patients may also demonstrate speech production errors. The overlap of speech production deficits in both disorders has raised questions on whether AOS emerges from a unique pattern of brain damage or as a subelement of the aphasic syndrome. The purpose of this study was to determine whether speech production errors in AOS and aphasia are associated with distinctive patterns of brain injury. Methods-Forty-three patients with history of a single left-hemisphere stroke underwent comprehensive speech and language testing. The AOS Rating Scale was used to rate speech errors specific to AOS versus speech errors that can also be associated with ...

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Section: Discussionmentioning

confidence: 99%

Patterns of Poststroke Brain Damage That Predict Speech Production Errors in Apraxia of Speech and Aphasia Dissociate

Basilakos

Rorden

Bonilha

et al. 2015

Stroke

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“…Several previous studies have examined speech errors in patients with an aphasia consequent to stroke (Ackermann & Riecker, 2004; Dronkers, 1996; Mumby, Bowen, & Hesketh, 2007; Peach & Tonkovich, 2004; Riecker et al, 2004). Apraxia of speech has been well documented in stroke patients (Dronkers, 1996), and other authors have explicitly compared errors of speech production in patients with fluent vs. nonfluent aphasia due to stroke (Canter et al, 1985; Romani et al, 2002).…”

Section: Discussionmentioning

confidence: 99%

Speech errors in progressive non-fluent aphasia

et al. 2010

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The nature and frequency of speech production errors in neurodegenerative disease have not previously been precisely quantified. In the present study, 16 patients with a progressive form of nonfluent aphasia (PNFA) were asked to tell a story from a wordless children's picture book. Errors in production were classified as either phonemic, involving language-based deformations that nevertheless result in possible sequences of English speech segments; or phonetic, involving a motor planning deficit and resulting in non-English speech segments. The distribution of cortical atrophy as revealed by structural MRI scans was examined quantitatively in a subset of PNFA patients (N=7). The few errors made by healthy seniors were only phonemic in type. PNFA patients made more than four times as many errors as controls. This included both phonemic and phonetic errors, with a preponderance of errors (82%) classified as phonemic. The majority of phonemic errors were substitutions that shared most distinctive features with the target phoneme. The systematic nature of these substitutions is not consistent with a motor planning deficit. Cortical atrophy was found in prefrontal regions bilaterally and peri-Sylvian regions of the left hemisphere. We conclude that the speech errors produced by PNFA patients are mainly errors at the phonemic level of language processing and are not caused by a motor planning impairment.

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“…However, consistency of diagnosis on the basis of clinical impression is far from good. While one recent study reported high consistency (Mumby et al, 2007), another reported staggering levels of inconsistency, at least when criteria were not specifically calibrated . Secondly, consistency, in itself, does not imply correct diagnosis.…”

Section: Introductionmentioning

confidence: 98%

Phonological simplifications, apraxia of speech and the interaction between phonological and phonetic processing

et al. 2015

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Research on aphasia has struggled to identify apraxia of speech (AoS) as an independent deficit affecting a processing level separate from phonological assembly and motor implementation. This is because AoS is characterized by both phonological and phonetic errors and, therefore, can be interpreted as a combination of deficits at the phonological and the motoric level rather than as an independent impairment. We apply novel psycholinguistic analyses to the perceptually phonological errors made by 24 Italian aphasic patients. We show that only patients with relative high rate (>10%) of phonetic errors make sound errors which simplify the phonology of the target. Moreover, simplifications are strongly associated with other variables indicative of articulatory difficulties - such as a predominance of errors on consonants rather than vowels - but not with other measures - such as rate of words reproduced correctly or rates of lexical errors. These results indicate that sound errors cannot arise at a single phonological level because they are different in different patients. Instead, different patterns: (1) provide evidence for separate impairments and the existence of a level of articulatory planning/programming intermediate between phonological selection and motor implementation; (2) validate AoS as an independent impairment at this level, characterized by phonetic errors and phonological simplifications; (3) support the claim that linguistic principles of complexity have an articulatory basis since they only apply in patients with associated articulatory difficulties.

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Apraxia of speech: how reliable are speech and language therapists' diagnoses?

Abstract: Despite controversy over its nature and existence, specialist speech and language therapists show high levels of agreement on the diagnosis of apraxia of speech using their clinical judgement.

Cited by 25 publications

References 17 publications

Patterns of Poststroke Brain Damage That Predict Speech Production Errors in Apraxia of Speech and Aphasia Dissociate

Patterns of Poststroke Brain Damage That Predict Speech Production Errors in Apraxia of Speech and Aphasia Dissociate

Speech errors in progressive non-fluent aphasia

Phonological simplifications, apraxia of speech and the interaction between phonological and phonetic processing

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