Bettina Brendel

Effectiveness of metrical pacing in the treatment of apraxia of speech

Background: One class of methods used in the treatment of apraxia of speech is based on rhythmic stimulation. Controlled trials investigating the effectiveness of these methods are still rare. This study, which was part of the PhD thesis of the first author (Brendel, 2003), was approved by the ethics committee of the Bayerische Ärztekammer, Munich. The first author was supported by DFG grant Zi 469/4‐1/4‐2. We are indebted to the speech‐language team of the Neuropsychological Department of the City Hospital Bogenhausen. Aims: To examine the effectiveness of a new treatment of apraxia of speech based on a metrical pacing technique (MPT) with acoustic stimulation. Methods & Procedures: MPT was applied to 10 patients with apraxia of speech. Conventional, non‐rhythmic therapeutic techniques were used as a control treatment (cross‐over design). Therapeutic effects were measured by variables describing speech rate, fluency, and segmental accuracy of sentence production. Corrections for spontaneous recovery were based on estimates inferred from a baseline period. Group statistics and multiple single case statistics were performed. Outcomes & Results: The complete intervention (MPT plus control treatment) yielded significant improvements in speech rate, fluency, and segmental accuracy. Regarding rate and fluency, MPT was superior to the control treatment. Regarding segmental accuracy, both treatments yielded comparable benefits. Conclusions: In a sample of 10 patients apraxia of speech could be modulated by behavioural treatment methods. The Metrical Pacing Therapy yielded specific improvements of rate and fluency, but also of segmental accuracy, which exceeded the effects of spontaneous recovery.

Friedreich Ataxia: Dysarthria Profile and Clinical Data

Friedreich ataxia (FRDA) is the most frequent recessive ataxia in the Western world. Dysarthria is a cardinal feature of FRDA, often leading to severe impairments in daily functioning, but its exact characteristics are only poorly understood so far. We performed a comprehensive evaluation of dysarthria severity and the profile of speech motor deficits in 20 patients with a genetic diagnosis of FRDA based on a carefully selected battery of speaking tasks and two widely used paraspeech tasks, i.e., oral diadochokinesis and sustained vowel productions. Perceptual ratings of the speech samples identified respiration, voice quality, voice instability, articulation, and tempo as the most affected speech dimensions. Whereas vocal instability predicted ataxia severity, tempo turned out as a significant correlate of disease duration. Furthermore, articulation predicted the overall intelligibility score as determined by a systematic speech pathology assessment tool. In contrast, neurologists’ ratings of intelligibility—a component of the “Scale for the Assessment and Rating of Ataxia”—were found to be related to perceived speech tempo. Obviously, clinicians are more sensitive to slowness of speech than to any other feature of spoken language during dysarthria evaluation. Our results suggest that different components of speech production and trunk/limb motor functions are differentially susceptible to FRDA pathology. Furthermore, evidence emerged that paraspeech tasks do not allow for an adequate scaling of speech deficits in FRDA.

Oral Motor Abilities Are Task Dependent: A Factor Analytic Approach to Performance Rate

ABSTRACT Measures of performance rates in speech-like or volitional nonspeech oral motor tasks are frequently used to draw inferences about articulation rate abnormalities in patients with neurologic movement disorders. The study objective was to investigate the structural relationship between rate measures of speech and of oral motor behaviors different from speech. A total of 130 patients with neurologic movement disorders and 130 healthy subjects participated in the study. Rate data was collected for oral reading (speech), rapid syllable repetition (speech-like), and rapid single articulator movements (nonspeech). The authors used factor analysis to determine whether the different rate variables reflect the same or distinct constructs. The behavioral data were most appropriately captured by a measurement model in which the different task types loaded onto separate latent variables. The data on oral motor performance rates show that speech tasks and oral motor tasks such as rapid syllable repetition or repetitive single articulator movements measure separate traits.

Dissociating oral motor capabilities: Evidence from patients with movement disorders

ABSTRACT Abnormal articulation rate is a frequent symptom in neurogenic speech disorders. Performance rates in speech‐like or nonspeech tasks involving the vocal motor apparatus are commonly accepted predictors of speech motor function in general and of articulation rate in particular. However, theoretical arguments and behavioral observations in populations with disordered speech indicate that different oral motor behaviors may be governed by distinct mechanisms. The objective of the present study was to expand our knowledge of the relationship between speech movements, on the one hand, and speech‐like and nonspeech oral motor behaviors, on the other, by using a rate paradigm. 130 patients with neurological movement disorders of different origins and 130 neurologically healthy subjects participated in the study. Rate data was collected in a speech task (oral reading/repetition), in speech‐like tasks (rapid syllable repetitions), and in nonspeech tasks (rapid single articulator movements of the tongue/lips). The main analyses involved a multiple single‐case method, by which we tested for differences among each patients performance rates on the three task types. The results disclosed statistically significant (classical and strong) dissociations between movement rates obtained from the speech task and those obtained from speech‐like and nonspeech oral motor tasks in a number of patients. The findings can be interpreted as reflecting major differences in task demands and underlying control mechanisms. The validity of diagnostic indices for speech obtained from speech‐like or nonspeech tasks must thus be called into question. HIGHLIGHTSSpeech is governed by task‐specific control mechanisms.Articulation rate cannot be reliably predicted by speech‐like or nonspeech rate indices.Dysarthria assessments should include articulation rate measures based on real speech.

Cerebellar Contributions to Speech and Language

It is well-established that the cerebellum participates in movement preparation/execution and motor skill acquisition, including the domain of speech production. Dysfunctions of this hindbrain component, therefore, may give rise to a distinct syndrome of articulatory and phonatory deficits (ataxic dysarthria). Furthermore, impaired perceptual encoding of temporal aspects of speech sounds could be documented in cerebellar patients. In addition, a variety of clinical and functional imaging data point to an engagement of the “small brain” in various cognitive-mental functions, even higher-order aspects of spoken language, and the regulation of behavior. As a possible morphological substrate, the cerebellar lobules interconnected with contralateral frontal areas underwent a disproportionate increase during the course of human evolution. At the computational level, there is some evidence for a contribution of these circuits to the temporal organization of a prearticulatory verbal code (“inner speech”) in terms of the concatenation of syllable strings (sequencing) into highly coarticulated sequences at an individual’s habitual speaking rate. Thus, cerebello-cerebral interactions could support verbal-executive functions, (e.g., subvocal working memory rehearsal). Finally, the tight reciprocal interactions between prefrontal cortex and lateral cerebellar hemispheres during a variety of mental tasks may provide—most presumably via crossed cerebello-cerebral diaschisis effects—a further basis for the emergence of higher-order language disorders such as aphasia-like or mutism-like syndromes.