Clinicoanatomic studies in dysarthria: review, critique, and directions for research

Longitudinal flortaucipir, metabolism and volume differ between phonetic and prosodic speech apraxia

Progressive apraxia of speech (PAOS) is a neurodegenerative motor-speech disorder that most commonly arises from a four-repeat tauopathy. Recent studies have established that progressive apraxia of speech is not a homogenous disease but rather there are distinct subtypes: the phonetic subtype is characterized by distorted sound substitutions, the prosodic subtype by slow and segmented speech and the mixed subtype by a combination of both but lack of predominance of either. There is some evidence that cross-sectional patterns of neurodegeneration differ across subtypes, although it is unknown whether longitudinal patterns of neurodegeneration differ. We examined longitudinal patterns of atrophy on MRI, hypometabolism on 18F-fluorodeoxyglucose-PET and tau uptake on flortaucipir-PET in a large cohort of subjects with PAOS that had been followed for many years. Ninety-one subjects with PAOS (51 phonetic, 40 prosodic) were recruited by the Neurodegenerative Research Group. Of these, 54 (27 phonetic, 27 prosodic) returned for annual follow-up, with up to seven longitudinal visits (total visits analysed = 217). Volumes, metabolism and flortaucipir uptake were measured for subcortical and cortical regions, for all scans. Bayesian hierarchical models were used to model longitudinal change across imaging modalities with PAOS subtypes being compared at baseline, 4 years from baseline, and in terms of rates of change. The phonetic group showed smaller volumes and worse metabolism in Broca's area and the striatum at baseline and after 4 years, and faster rates of change in these regions, compared with the prosodic group. There was also evidence of faster spread of hypometabolism and flortaucipir uptake into the temporal and parietal lobes in the phonetic group. In contrast, the prosodic group showed smaller cerebellar dentate, midbrain, substantia nigra and thalamus volumes at baseline and after 4 years, as well as faster rates of atrophy, than the phonetic group. Greater hypometabolism and flortaucipir uptake were also observed in the cerebellar dentate and substantia nigra in the prosodic group. Mixed findings were observed in the supplementary motor area and precentral cortex, with no clear differences observed across phonetic and prosodic groups. These findings support different patterns of disease spread in PAOS subtypes, with corticostriatal patterns in the phonetic subtype and brainstem and thalamic patterns in the prosodic subtype, providing insight into the pathophysiology and heterogeneity of PAOS.

Mechanisms of Swallowing, Speech and Voice Disorders in Parkinson's Disease: Literature Review with Our First Evidence for the Periperal Nervous System Involvement

The majority of patients with Parkinson's disease (PD) develop swallowing, speech, and voice (SSV) disorders. Importantly, swallowing difficulty or dysphagia and related aspiration are life-threatening conditions for PD patients. Although PD treatments have significant therapeutic effects on limb motor function, their effects on SSV disorders are less impressive. A large gap in our knowledge is that the mechanisms of SSV disorders in PD are poorly understood. PD was long considered to be a central nervous system disorder caused by the death of dopaminergic neurons in the basal ganglia. Aggregates of phosphorylated α-synuclein (PAS) underlie PD pathology. SSV disorders were thought to be caused by the same dopaminergic problem as those causing impaired limb movement; however, there is little evidence to support this. The pharynx, larynx, and tongue play a critical role in performing upper airway (UA) motor tasks and their dysfunction results in disordered SSV. This review aims to provide an overview on the neuromuscular organization patterns, functions of the UA structures, clinical features of SSV disorders, and gaps in knowledge regarding the pathophysiology underlying SSV disorders in PD, and evidence supporting the hypothesis that SSV disorders in PD could be associated, at least in part, with PAS damage to the peripheral nervous system controlling the UA structures. Determining the presence and distribution of PAS lesions in the pharynx, larynx, and tongue will facilitate the identification of peripheral therapeutic targets and set a foundation for the development of new therapies to treat SSV disorders in PD.

Neural basis of speech and grammar symptoms in non-fluent variant primary progressive aphasia spectrum

The non-fluent/agrammatic variant of primary progressive aphasia (nfvPPA) is a neurodegenerative syndrome primarily defined by the presence of apraxia of speech (AoS) and/or expressive agrammatism. In addition, many patients exhibit dysarthria and/or receptive agrammatism. This leads to substantial phenotypic variation within the speech-language domain across individuals and time, in terms of both the specific combination of symptoms as well as their severity. How to resolve such phenotypic heterogeneity in nfvPPA is a matter of debate. 'Splitting' views propose separate clinical entities: 'primary progressive apraxia of speech' when AoS occurs in the absence of expressive agrammatism, 'progressive agrammatic aphasia' (PAA) in the opposite case, and 'AOS + PAA' when mixed motor speech and language symptoms are clearly present. While therapeutic interventions typically vary depending on the predominant symptom (e.g. AoS versus expressive agrammatism), the existence of behavioural, anatomical and pathological overlap across these phenotypes argues against drawing such clear-cut boundaries. In the current study, we contribute to this debate by mapping behaviour to brain in a large, prospective cohort of well characterized patients with nfvPPA (n = 104). We sought to advance scientific understanding of nfvPPA and the neural basis of speech-language by uncovering where in the brain the degree of MRI-based atrophy is associated with inter-patient variability in the presence and severity of AoS, dysarthria, expressive agrammatism or receptive agrammatism. Our cross-sectional examination of brain-behaviour relationships revealed three main observations. First, we found that the neural correlates of AoS and expressive agrammatism in nfvPPA lie side by side in the left posterior inferior frontal lobe, explaining their behavioural dissociation/association in previous reports. Second, we identified a 'left-right' and 'ventral-dorsal' neuroanatomical distinction between AoS versus dysarthria, highlighting (i) that dysarthria, but not AoS, is significantly influenced by tissue loss in right-hemisphere motor-speech regions; and (ii) that, within the left hemisphere, dysarthria and AoS map onto dorsally versus ventrally located motor-speech regions, respectively. Third, we confirmed that, within the large-scale grammar network, left frontal tissue loss is preferentially involved in expressive agrammatism and left temporal tissue loss in receptive agrammatism. Our findings thus contribute to define the function and location of the epicentres within the large-scale neural networks vulnerable to neurodegenerative changes in nfvPPA. We propose that nfvPPA be redefined as an umbrella term subsuming a spectrum of speech and/or language phenotypes that are closely linked by the underlying neuroanatomy and neuropathology.

Behavioral Therapy for Tremor or Dystonia Affecting Voice in Speakers with Hyperkinetic Dysarthria: A Systematic Review

INTRODUCTION

Hyperkinetic dysarthria is characterized by atypical involuntary movements within the speech mechanism that may affect the respiratory, laryngeal, pharyngeal-oral, or velopharyngeal-nasal subsystems and may alter speech production. Although articulatory impairments are commonly considered in hyperkinetic dysarthria, speakers with hyperkinetic dysarthria may also present with changes in voice quality, pitch, and loudness. In approximately 70% of speakers with hyperkinetic dysarthria, these voice alterations are associated with tremor or dystonia. The purpose of this systematic review was to investigate the association between behavioral therapy for tremor or dystonia affecting voice in speakers with hyperkinetic dysarthria and improvement in the functional, perceptual, acoustical, aerodynamic, or endoscopic characteristics of voice.

METHOD

MEDLINE (PubMed), Embase, PsycINFO, and ClinicalTrials.gov online databases were searched in August 2017, December 2018, and April 2020 for relevant studies. The searches provided 4,921 unique records, and six additional unique records were added from other sources. Twelve studies met the criteria for inclusion in the systematic review. Participants who received concurrent medical treatment were included in this review to ensure that the search was inclusive of all relevant studies and informative for typical clinical scenarios.

RESULTS

The most commonly administered treatment ingredient was relaxation training, which was investigated in three of the four studies on tremor and three of the eight studies on dystonia. Of these six studies, only one used an experimental design and administered relaxation training as the only behavioral approach. This single-case experiment reported a significant reduction in participant ratings of tremor severity and interference with activities of daily living, although the speaking subscale reportedly did not improve and oral medications were administered concurrently. In two group studies that tested potential behavioral therapy targets, production of a low pitch improved acoustical measures for participants with essential tremor and improved auditory-perceptual judgments for participants with laryngeal dystonia. Behavioral therapy improved functional, acoustical, and aerodynamic outcomes in participants with laryngeal dystonia who were also receiving botulinum toxin injections in a randomized cross-over study and a non-randomized controlled study. Because one study employed easy onset and breathing exercises, while the other employed loud voice exercises, the mechanism of action for improvement in voice associated with behavioral therapy requires further investigation.

CONCLUSION

This systematic review describes the current evidence for treatment of tremor and dystonia affecting voice in speakers with hyperkinetic dysarthria and highlights the need for future research on behavioral therapy for these disorders.

Effect of speech therapy on quality of life in patients with spinocerebelar ataxia type 3

BACKGROUND

Individuals with spinocerebellar ataxia type 3 (SCA3) present communication and swallowing disorders, and consequent deterioration in quality of life (QOL).

OBJECTIVE

To evaluate the impact of a speech therapy rehabilitation program on the QOL of patients with SCA3.

METHODS

All participants were randomly assigned to two groups, an intervention group receiving speech therapy (STG) and a control group (CG). The International Cooperative Ataxia Rating Scale scores were 32.4 ± 20.2, and the Scale for the Assessment and Rating of Ataxia scores were 11.8 ± 8.0. The intervention consisted of a 12-session speech therapy rehabilitation program with oral, pharyngeal, and laryngeal strengthening exercises-the so-called ATAXIA-Myofunctional Orofacial and Vocal Therapy (A-MOVT). They all were submitted to pre- and postintervention evaluations using the World Health Organization's Quality of Life (WHOQOL-BREF) assessment, as well as the Living with Dysarthria (LwD), Quality of Life in Swallowing Disorders (SWAL-QOL), and Food Assessment Tool (EAT-10).

RESULTS

The study sample consisted of 48 patients with SCA3 (STG = 25; CG = 23), mean age was 47.1 ± 11.4 years; mean age at symptom onset was 36.9 ± 11.3 years; disease duration was 11.9 ± 13.3 years. After the 3-month intervention, there were significant changes in the QOL in the STG compared with the CG, when assessed by the LwD (179.12 ± 62.55 vs. 129.88 ± 51.42, p < 0.001), SWAL-QOL (869.43 ± 153.63 vs. 911.60 ± 130.90, p = 0.010), and EAT-10 (5.16 ± 7.55 vs. 2.08 ± 3.85, p = 0.018).

CONCLUSIONS

Patients with SCA3 should receive continuous speech therapy as part of the A-MOVT program, because therapy helps to improve difficulty swallowing and dysarthria.

Substrates of speech treatment-induced neuroplasticity in adults and children with motor speech disorders: A systematic scoping review of neuroimaging evidence

Purpose: Neuroimaging may provide clinical evidence for speech treatment-induced neuroplasticity. This review aimed to report the current scope of evidence relating to brain changes identified using neuroimaging techniques, following effective speech intervention in adults and children with motor speech disorders (MSD).Method: Studies were retrieved from five electronic databases (PubMed, CINAHL, EMBASE (Medline), SCOPUS, and Web of Science) and a general internet search.Result: Seven studies met the inclusion criteria. Using structural or functional neuroimaging techniques, five studies reported on the effects of the Lee Silverman Voice Treatment for dysarthria in adults and children, one study on the outcome of rhythmic-melodic voice training in adults with apraxia of speech, and one study on the effects of Prompts for Restructuring Oral Muscular Phonetic Targets therapy in children with idiopathic apraxia of speech. Identified brain changes included: enhanced white matter tract integrity; normalisation of baseline cortical activity; right-hemisphere shifts in re-organisation; perilesional activations; and cortical thinning.Conclusion: The current review identified preliminary evidence for treatment-dependent brain changes in adults and children with MSD. Although important to interpret within the context of Phase I research, the identification of therapeutic effects across seven heterogeneous studies suggests that treatment-induced improvements in speech performance are underpinned by demonstrable alterations in brain structure and/or function. Future research is required to better define these mechanisms of neuronal re-organisation in individuals receiving treatment for MSD, including their prognostic potential.

Speech-Language Pathology Evaluation and Management of Hyperkinetic Disorders Affecting Speech and Swallowing Function

Background

Hyperkinetic dysarthria is characterized by abnormal involuntary movements affecting respiratory, phonatory, and articulatory structures impacting speech and deglutition. Speech–language pathologists (SLPs) play an important role in the evaluation and management of dysarthria and dysphagia. This review describes the standard clinical evaluation and treatment approaches by SLPs for addressing impaired speech and deglutition in specific hyperkinetic dysarthria populations.

Methods

A literature review was conducted using the data sources of PubMed, Cochrane Library, and Google Scholar. Search terms included 1) hyperkinetic dysarthria, essential voice tremor, voice tremor, vocal tremor, spasmodic dysphonia, spastic dysphonia, oromandibular dystonia, Meige syndrome, orofacial, cervical dystonia, dystonia, dyskinesia, chorea, Huntington’s Disease, myoclonus; and evaluation/treatment terms: 2) Speech–Language Pathology, Speech Pathology, Evaluation, Assessment, Dysphagia, Swallowing, Treatment, Management, and diagnosis.

Results

The standard SLP clinical speech and swallowing evaluation of chorea/Huntington’s disease, myoclonus, focal and segmental dystonia, and essential vocal tremor typically includes 1) case history; 2) examination of the tone, symmetry, and sensorimotor function of the speech structures during non-speech, speech and swallowing relevant activities (i.e., cranial nerve assessment); 3) evaluation of speech characteristics; and 4) patient self-report of the impact of their disorder on activities of daily living. SLP management of individuals with hyperkinetic dysarthria includes behavioral and compensatory strategies for addressing compromised speech and intelligibility. Swallowing disorders are managed based on individual symptoms and the underlying pathophysiology determined during evaluation.

Discussion

SLPs play an important role in contributing to the differential diagnosis and management of impaired speech and deglutition associated with hyperkinetic disorders.

The pulvinar nucleus is associated with the presence of dysarthria in patients with basal ganglia hemorrhage

Dysarthria is a frequent symptom in patients with stroke. The anatomical structures responsible for dysarthria have been reported in patients with lacunar infarcts, but the related lesions in patients with basal ganglia hemorrhage (BGH) have not been investigated. The aim of this study was to identify associations between the lesion location and the presence/absence of dysarthria in patients with BGH using voxel-based lesion symptom mapping (VLSM) analyses. A retrospective analysis was conducted on 26 patients with acute BGH (mean age, 54.0 years; men:women, 14:12) who underwent conservative management. The patients were classified into groups based on the presence or absence of dysarthria at the time of admission, which was determined by reviewing the patients' medical records. Brain lesions were traced on magnetic resonance images that were acquired within the first 3 weeks after BGH onset, and then separate high-resolution region-of-interest images were generated. Associations between dysarthria and the lesion location were determined with the VLSM analyses. The average volume of the delimited lesions was 7.38±5.75cm³. The VLSM analyses identified several voxel clusters, mainly in the pulvinar nucleus of the left thalamus, that were significantly related to the presence of dysarthria at admission. These findings suggest that patients with BGH extending into the left pulvinar nucleus should be monitored for dysarthria.

Asphyxia due to laryngeal spasm as a severe complication of awake deep brain stimulation for Parkinson's disease: a case report

BACKGROUND

In accordance with German neurosurgical and neurological consensus recommendations, lead placements for deep brain stimulation (DBS) in patients with Parkinson's disease (PD) are usually performed with the patient awake and in "medication off" state. This allows for optimal lead position adjustment according to the clinical response to intraoperative test stimulation. However, exacerbation of Parkinsonian symptoms after withdrawal of dopaminergic medication may endanger the patient by inducing severe "off" state motor phenomena. In particular, this can be a problem in awake craniotomies utilizing intraoperative airway management and resuscitation.

CASE PRESENTATION

We report the case of a PD patient with progressive orofacial and neck muscle dystonia resulting in laryngeal spasm during DBS lead placement. This led to upper airway compromise and asphyxia, requiring resuscitation.

CONCLUSIONS

Laryngeal spasms may occur as a rare "off" state motor complication in patients with PD. Other potential causes of intraoperative difficulties breathing include bilateral vocal cord palsy, positional asphyxia, and silent aspiration. In our practice, we have adjusted our medication regimen and now allow patients to receive their standard dopaminergic medication until the morning of surgery. Neurologists and neurosurgeons performing lead placement procedures for PD should be aware of this rare but unsafe condition to most optimized treatment.

Communicating with Patients with Special Health Care Needs

People with special health care needs (PSHCN) often have difficulty communicating with providers in health care settings, including dental practices. This difficulty can affect access to care as well as the quality of care received. This article provides practical tips and tools dental professionals can use to facilitate communication for a diverse population of PSHCNs. The article discusses communication needs of patients with communication disorders; augmentative and alternative communication; and communication for patients with intellectual disability, psychiatric conditions; and dental fears. Examples are given of communication breakdowns, and descriptions of how communication challenges can be resolved.

The role of subcortical structures in recited speech: Studies in Parkinson's disease

The role of subcortical structures in language function is complex and dependent on language task, with studies increasingly showing subcortical involvement for the production of formulaic language, including recited speech. Individuals with Parkinson's disease (PD), with (n = 6) and without (n = 7) surgical treatment, deep brain stimulation (DBS), were compared to healthy adults (n = 14) to determine whether individuals with subcortical dysfunction produce more errors during a recitation speech task. Participants were asked to recite poems, prayers, and rhymes familiar to them in order to determine the effects of subcortical disease on recited speech ability. When compared with healthy controls, the DBS-OFF group produced significantly more error words, suggesting that deficits in recitation arise with severe states of subcortical dysfunction. Individuals with DBS in the ON or OFF conditions did not differ significantly during the recited speech task. Results support a model of language where large units of overlearned language are at least partially modulated by subcortical structures.

Clinical and imaging characterization of progressive spastic dysarthria

BACKGROUND AND PURPOSE

To describe speech, neurological and imaging characteristics of a series of patients presenting with progressive spastic dysarthria as the first and predominant sign of a presumed neurodegenerative disease.

METHODS

Participants were 25 patients with spastic dysarthria as the only or predominant speech disorder. Clinical features, pattern of MRI volume loss on voxel-based morphometry and pattern of hypometabolism on F18-fluorodeoxyglucose positron emission tomography (FDG-PET) scan are described.

RESULTS

All patients demonstrated speech characteristics consistent with spastic dysarthria, including strained voice quality, slow speaking rate, monopitch and monoloudness, and slow and regular speech alternating motion rates. Eight patients did not have additional neurological findings on examination. Pseudobulbar affect, upper motor neuron pattern limb weakness, spasticity, Hoffman sign and positive Babinski reflexes were noted in some of the remaining patients. Twenty-three patients had electromyographic assessment and none had diffuse motor neuron disease or met El Escorial criteria for amyotrophic lateral sclerosis. Voxel-based morphometry revealed striking bilateral white matter volume loss affecting the motor cortex (BA 4), including the frontoparietal operculum (BA 43) with extension into the middle cerebral peduncle. FDG-PET showed subtle hypometabolism affecting the premotor and motor cortices in some patients, particularly in those who had a disease duration longer than 2 years.

CONCLUSIONS

A neurodegenerative disorder that begins focally with spastic dysarthria due to involvement of the motor and premotor cortex and descending corticospinal and corticobulbar pathways is characterized. The descriptive label 'progressive spastic dysarthria' to best capture the dominant presenting feature of the syndrome is proposed.

Auditory-perceptual speech analysis in children with cerebellar tumours: a long-term follow-up study

Mutism and Subsequent Dysarthria (MSD) and the Posterior Fossa Syndrome (PFS) have become well-recognized clinical entities which may develop after resection of cerebellar tumours. However, speech characteristics following a period of mutism have not been documented in much detail. This study carried out a perceptual speech analysis in 24 children and adolescents (of whom 12 became mute in the immediate postoperative phase) 1-12.2 years after cerebellar tumour resection. The most prominent speech deficits in this study were distorted vowels, slow rate, voice tremor, and monopitch. Factors influencing long-term speech disturbances are presence or absence of postoperative PFS, the localisation of the surgical lesion and the type of adjuvant treatment. Long-term speech deficits may be present up to 12 years post-surgery. The speech deficits found in children and adolescents with cerebellar lesions following cerebellar tumour surgery do not necessarily resemble adult speech characteristics of ataxic dysarthria.

Pharmacological aspects and neurological speech therapy: target of dysphony, dysarthria and dysphagia

The word dysphagy was suggested by Nicolatopoulos (1907) and derives from the ancient Greek &#x0022;duz&#x0022;, which means &#x0022;difficulty&#x0022; and &#x0022;katapinein&#x0022;, which means &#x0022;to swallow&#x0022;. Generally, the dysphagia is defined on the basis of its origin: oral, pharynx and oesophagus, otherwise by its mechanical or neurological aetiology. The symptoms are dependent on the nature of the lesions in the affected organs. The swallow is a complex motor sequence dependent on the coordinate contraction of the muscle of mouth, of larynx and of the oesophagus. The mechanical action of the swallow helps the liquid or solid food progression from mouth to stomach thanks to cooperation of 31 muscles and 5 cranial nerves and allows swallowing about 580 times approximately. The dysphagy in neurological diseases is mainly due to the following reasons. Increase of vascular cerebral disease, increase of population age and increase of road and work traumas. The difficulties in swallowing causes heavy social problems like meager diet, social isolation and worsening of quality of life. The speech rehabilitation requires the involvement of care givers through a re-educational program that takes place in two periods: the first of relaxation, and the second of restoration of phonodeglutition praxis.

Neural bases of childhood speech disorders: lateralization and plasticity for speech functions during development

Current models of speech production in adults emphasize the crucial role played by the left perisylvian cortex, primary and pre-motor cortices, the basal ganglia, and the cerebellum for normal speech production. Whether similar brain-behaviour relationships and leftward cortical dominance are found in childhood remains unclear. Here we reviewed recent evidence linking motor speech disorders (apraxia of speech and dysarthria) and brain abnormalities in children and adolescents with developmental, progressive, or childhood-acquired conditions. We found no evidence that unilateral damage can result in apraxia of speech, or that left hemisphere lesions are more likely to result in dysarthria than lesion to the right. The few studies reporting on childhood apraxia of speech converged towards morphological, structural, metabolic or epileptic anomalies affecting the basal ganglia, perisylvian and rolandic cortices bilaterally. Persistent dysarthria, similarly, was commonly reported in individuals with syndromes and conditions affecting these same structures bilaterally. In conclusion, for the first time we provide evidence that longterm and severe childhood speech disorders result predominantly from bilateral disruption of the neural networks involved in speech production.

Cerebellar ataxia: pathophysiology and rehabilitation

This series of articles for rehabilitation in practice aims to cover a knowledge element of the rehabilitation medicine curriculum. Nevertheless they are intended to be of interest to a multidisciplinary audience. The competency addressed in this article is 'The trainee consistently demonstrates a knowledge of management approaches for specific impairments including spasticity, ataxia.'

Role of cerebellum in fine speech control in childhood: persistent dysarthria after surgical treatment for posterior fossa tumour

Dysarthria following surgical resection of childhood posterior fossa tumour (PFT) is most commonly documented in a select group of participants with mutism in the acute recovery phase, thus limiting knowledge of post-operative prognosis for this population of children as a whole. Here we report on the speech characteristics of 13 cases seen long-term after surgical treatment for childhood PFT, unselected for the presence of post-operative mutism (mean time post-surgery=6y10m, range 1;4-12;6 years, two had post-operative mutism), and examine factors affecting outcome. Twenty-six age- and sex- matched healthy controls were recruited for comparison. Participants in both groups had speech assessments using detailed perceptual and acoustic methods. Over two-thirds of the group (69%) with removal of PFT had a profile of typically mild dysarthria. Prominent speech deficits included consonant imprecision, reduced rate, monopitch and monoloudness. We conclude that speech deficits may persist even up to 10 years post-surgery in participants who have not shown mutism in the acute phase. Of cases with unilateral lesions, poorer outcomes were associated with right cerebellar tumours compared to left, consistent with the notion based on adult data that speech is controlled by reciprocal right cerebellar/left frontal interactions. These results confirm the important role of the cerebellum in the control of fine speech movements in children.

Speech and oral motor profile after childhood hemispherectomy

Hemispherectomy (disconnection or removal of an entire cerebral hemisphere) is a rare surgical procedure used for the relief of drug-resistant epilepsy in children. After hemispherectomy, contralateral hemiplegia persists whereas gross expressive and receptive language functions can be remarkably spared. Motor speech deficits have rarely been examined systematically, thus limiting the accuracy of postoperative prognosis. We describe the speech profiles of hemispherectomized participants characterizing their intelligibility, articulation, phonological speech errors, dysarthric features, and execution and sequencing of orofacial speech and non-speech movements. Thirteen participants who had undergone hemispherectomy (six left, seven right; nine with congenital, four with acquired hemiplegia; operated between four months and 13 years) were investigated. Results showed that all participants were intelligible but showed a mild dysarthric profile characterized by neuromuscular asymmetry and reduced quality and coordination of movements, features that are characteristic of adult-onset unilateral upper motor neuron dysarthria, flaccid-ataxic variant. In addition, one left and four right hemispherectomy cases presented with impaired production of speech and non-speech sequences. No participant showed evidence of verbal or oral dyspraxia. It is concluded that mild dysarthria is persistent after left or right hemispherectomy, irrespective of age at onset of hemiplegia. These results indicate incomplete functional re-organization for the control of fine speech motor movements throughout childhood, and provide no evidence of hemispheric differences.

Differential motor speech outcomes in children treated for mid-line cerebellar tumour

PRIMARY OBJECTIVE

To investigate the nature of the motor speech impairments and dysarthria that can arise subsequent to treatment for childhood mid-line cerebellar tumours (CMCT).

RESEARCH DESIGN

The motor speech ability of six cases of children with CMCT was analysed using perceptual and physiological measures and compared with that of a group of non-neurologically impaired children matched for age and sex.

MAIN OUTCOME AND RESULTS

Three of the children with CMCT were perceived to exhibit dysarthric speech, while the remaining three were judged to have normal speech. The speech disorder in three of the children with CMCT was marked by deviances in prosody, articulation and phonation. The underlying pathophysiology was linked to cerebellar damage and expressed as difficulty in co-ordinating the motor speech musculature as required for speech production. These deficits were not identified in the three non-dysarthric children with CMCT.

CONCLUSION

Differential motor speech outcomes occur for children treated for CMCT and these are discussed within the realm of possible mechanisms responsible for these differences. The need for further investigation of the risk factors for development of motor speech impairment in children treated for CMCT is also highlighted.

Speech and language disorders secondary to diffuse subcortical vascular lesions: Neurolinguistic and acoustic analysis. A case report

BACKGROUND AND PURPOSE

Subcortical white matter (WM) plays an important role in speech production and language processing. Most frequently, cerebral WM lesions are secondary to small vessel disease in patients with vascular risk factors. We report the case of a 53-year-old man with history of hypertension and ischemic subcortical lesions, who presented with speech difficulties and mild cognitive impairment.

METHODS

Language and cognitive assessment included Boston Diagnostic Aphasia Examination, Boston Naming Test, Rey Auditory-Verbal Learning Test, Rey-Osterrieth Complex Figure Test, Trail Making Test A and B, Wisconsin Card Sorting Test, Scale for Evaluation of Perceptive Characteristics of Voice and Speech, and Multidimensional Evaluation of Speech and Voice.

RESULTS

Brain MRI showed ischemic WM lesions and lacunar infarcts in the brainstem and right cerebellum. Cognitive testing revealed mild cognitive impairment, predominantly affecting attention and executive functions. Speech and language analysis demonstrated dysarthria, dysphonia with hypophonia, and imprecise articulation, as well as short rushes of speech, palilalia and mild subcortical dysphasia.

CONCLUSIONS

Neurolinguistic and acoustic analysis in patients with ischemic WM lesions can provide additional information in the understanding of language and speech disturbances, and can assist in patient management.

Evaluation of language functions in acute cerebellar vascular diseases

BACKGROUND

The principal features of the cerebellar infarcts are ataxia, failure of coordination, gait instability, and articulation and eye movement disabilities. Language disabilities are also seen with cerebellar lesions, but there are difficulties in diagnosis. This study was planned to evaluate the effects of cerebellar lesions on language functions and the relation between these functions and lesion type, age, and education level.

METHODS

A total of 20 patients, 13 male (65%) and 7 female (35%), were included in this study. Twenty control subjects with similar demographic characteristics were also included. The mean age of the patient group was not statistically different.

RESULTS

Patients with vermal lesions had significantly higher performance than patients with paravermal lesions when evaluating the understanding of hearing and total aphasia score. Understanding of reading function was significantly better in the patients with small lesions compared with those with large lesions. When the aphasia parameters were compared between the patient and control groups, significant differences were found for all parameters, which reflected the language abilities understanding, naming, true-wrong questions, complex questions, comparing, repeating, and total aphasia score. Reading and writing functions were also significantly different between the patients and the control subjects.

CONCLUSION

We found that the cerebellum contributes in several language parameters. These functions show difference according to localization and lesion volume of cerebellar disease. Aphasia should be explored as an important parameter when evaluating the loss of function in patients with cerebellar lesions.

A neuroimaging study of premotor lateralization and cerebellar involvement in the production of phonemes and syllables

PURPOSE

This study investigated the network of brain regions involved in overt production of vowels, monosyllables, and bisyllables to test hypotheses derived from the Directions Into Velocities of Articulators (DIVA) model of speech production (Guenther, Ghosh, & Tourville, 2006). The DIVA model predicts left lateralized activity in inferior frontal cortex when producing a single syllable or phoneme and increased cerebellar activity for consonant-vowel syllables compared with steady-state vowels.

METHOD

Sparse sampling functional magnetic resonance imaging (fMRI) was used to collect data from 10 right-handed speakers of American English while producing isolated monosyllables (e.g., "ba," "oo"). Data were analyzed using both voxel-based and participant-specific anatomical region-of-interest-based techniques.

RESULTS

Overt production of single monosyllables activated a network of brain regions, including left ventral premotor cortex, left posterior inferior frontal gyrus, bilateral supplementary motor area, sensorimotor cortex, auditory cortex, thalamus, and cerebellum. Paravermal cerebellum showed greater activity for consonant-vowel syllables compared to vowels.

CONCLUSIONS

The finding of left-lateralized premotor cortex activity supports the DIVA model prediction that this area contains cell populations representing syllable motor programs without regard for semantic content. Furthermore, the superior paravermal cerebellum is more active for consonant-vowel syllables compared with vowels, perhaps due to increased timing constraints for consonant production.

The neural basis of ataxic dysarthria

Lesions to the cerebellum often give rise to ataxic dysarthria which is characterized by a primary disruption to articulation and prosody. Converging evidence supports the likelihood of speech motor programming abnormalities in addition to speech execution deficits. The understanding of ataxic dysarthria has been further refined by the development of neural network models and neuroimaging studies. A critical role of feedforward processing by the cerebellum has been established and linked to speech motor control and to aspects of ataxic dysarthria. Moreover, this research has helped to define models of the cerebellar contributions to speech processing and production, and to posit possible regions of speech localization within the cerebellum. Bilateral, superior areas of the cerebellum appear to mediate speech motor control while a putative role of the right cerebellar hemispheres in the planning and processing of speech has been suggested.

Parametric quantitative acoustic analysis of conversation produced by speakers with dysarthria and healthy speakers

PURPOSE

This study's main purpose was to (a) identify acoustic signatures of hypokinetic dysarthria (HKD) that are robust to phonetic variation in conversational speech and (b) determine specific characteristics of the variability associated with HKD.

METHOD

Twenty healthy control (HC) participants and 20 participants with HKD associated with idiopathic Parkinson's disease (PD) repeated 3 isolated sentences (controlled phonetic content) and 2 min of conversational speech (phonetic content treated as a random variable). A MATLAB-based program automatically calculated measures of contrastivity: speech-pause ratio, intensity variation, median and maximum formant slope, formant range, change in the upper and lower spectral envelope, and range of the spectral envelope. t tests were used to identify which measures were sensitive to HKD and which measures differed by task. Discriminant analysis was used to identify the combination of measures that best predicted HKD, and this analysis was then used as a general measure of contrastivity (Contrastivity Index). Differential effects of HKD on maximum and typical contrastivity levels were tested with interaction of maximum, minimum, and median observations of individual speakers and with pairwise comparisons of skewness and kurtosis of the contrastivity index distributions.

RESULTS

Group differences were detected with pairwise comparisons with t tests in 8 of the 9 measures. Percentage pause time and spectral range were identified as the most specific (95%) and accurate (95%) differentiators of HKD and HC conversational speech. Sentence repetition elicited significantly higher levels of contrastivity than conversational speech in both HC and HKD speakers. Maximum and minimum contrastivities were significantly lower in HKD speech, but there was no evidence that HKD affects maximum contrastivity levels more than median contrastivity levels. The HKD speakers' contrastivity distributions were significantly more skewed to lower levels of production.

CONCLUSION

HKD can be consistently distinguished from HC speech in both sentence repetition and conversational speech on the basis of intensity variation and spectral range. Although speakers with HKD were effectively able to produce higher contrastivity levels in sentence repetition tasks, they habitually performed closer to the lower end of their production ranges.

Imaging speech production using fMRI

Human speech is a well-learned, sensorimotor, and ecological behavior ideal for the study of neural processes and brain-behavior relations. With the advent of modern neuroimaging techniques such as positron emission tomography (PET) and functional magnetic resonance imaging (fMRI), the potential for investigating neural mechanisms of speech motor control, speech motor disorders, and speech motor development has increased. However, a practical issue has limited the application of fMRI to issues in spoken language production and other related behaviors (singing, swallowing). Producing these behaviors during volume acquisition introduces motion-induced signal changes that confound the activation signals of interest. A number of approaches, ranging from signal processing to using silent or covert speech, have attempted to remove or prevent the effects of motion-induced artefact. However, these approaches are flawed for a variety of reasons. An alternative approach, that has only recently been applied to study single-word production, uses pauses in volume acquisition during the production of natural speech motion. Here we present some representative data illustrating the problems associated with motion artefacts and some qualitative results acquired from subjects producing short sentences and orofacial nonspeech movements in the scanner. Using pauses or silent intervals in volume acquisition and block designs, results from individual subjects result in robust activation without motion-induced signal artefact. This approach is an efficient method for studying the neural basis of spoken language production and the effects of speech and language disorders using fMRI.

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.