Ludlow, Christy L.

Objective The purpose of this review is to describe the recent advances in identifying possible factors involved in the pathogenesis of spasmodic dysphonia. Spasmodic dysphonia is a task‐specific focal laryngeal dystonia characterized by irregular and uncontrolled voice breaks. Pathogenesis of the disorder is poorly understood. Data Sources PubMed, Google Scholar, and Cochrane Library. Review Methods The data sources were searched using the following search terms: ( spasmodic dysphonia or laryngeal dystonia ) and ( etiology, aetiology, diagnosis, pathogenesis , or pathophysiology ). Conclusions Several potential etiological factors have been proposed by epidemiological, genetic, and neuropathological studies. Spasmodic dysphonia is a rare disorder primarily affecting females beginning in their 40s. Vocal tremor co‐occurs in 30% to 60%. Large cohort studies identified risk factors such as a family history of neurological disorders including dystonia and tremor, recent viral illness, and heavy voice use. As none are rare events, a complex interactive process may contribute to pathogenesis in a small proportion of those at risk. Consequences to pathogenesis are neurological processes found in spasmodic dysphonia: loss of cortical inhibition, sensory processing disturbances, and neuroanatomical and physiological differences in the laryngeal motor control system. Implications for Practice Diagnosis of spasmodic dysphonia usually includes speech and laryngoscopic assessment. However, as diagnosis is sometimes problematic, measurement of neurophysiological abnormalities may contribute useful adjuncts for the diagnosis of spasmodic dysphonia in the future.

ObjectiveThe purpose of this review is to describe the recent advances in characterizing spasmodic dysphonia. Spasmodic dysphonia is a task‐specific focal laryngeal dystonia characterized by irregular and uncontrolled voice breaks. The pathophysiology is poorly understood, and there are diagnostic difficulties.Data SourcesPubMed, Google Scholar, and Cochrane Library.Review MethodsThe data sources were searched using the following search terms: (spasmodic dysphonia or laryngeal dystonia) and (etiology, aetiology, diagnosis, pathogenesis, or pathophysiology).ConclusionThe diagnosis of spasmodic dysphonia can be difficult due to the lack of a scientific consensus on diagnostic criteria and the fact that other voice disorders may present similarly. Confusion can arise between spasmodic dysphonia and muscle tension dysphonia. Spasmodic dysphonia symptoms are tied to particular speech sounds, whereas muscle tension dysphonia is not. With the advent of more widespread use of high‐speed laryngoscopy and videokymography, measures of the disruptions in phonation and delays in the onset of vocal fold vibration after vocal fold closure can be quantified. Recent technological developments have expanded our understanding of the pathophysiology of spasmodic dysphonia.Implications for PracticeA 3‐tiered approach, involving a questionnaire, followed by speech assessment and nasolaryngoscopy is the most widely accepted method for making the diagnosis in most cases. More experimental and invasive techniques such as electromyography and neuroimaging have been explored to further characterize spasmodic dysphonia and aid in diagnosing difficult cases.

ObjectiveTo identify research priorities to increase understanding of the pathogenesis, diagnosis, and improved treatment of spasmodic dysphonia.Study Design and SettingA multidisciplinary working group was formed that included both scientists and clinicians from multiple disciplines (otolaryngology, neurology, speech pathology, genetics, and neuroscience) to review currently available information on spasmodic dysphonia and to identify research priorities.ResultsOperational definitions for spasmodic dysphonia at different levels of certainty were recommended for diagnosis and recommendations made for a multicenter multidisciplinary validation study.ConclusionsThe highest priority is to characterize the disorder and identify risk factors that may contribute to its onset. Future research should compare and contrast spasmodic dysphonia with other forms of focal dystonia. Development of animal models is recommended to explore hypotheses related to pathogenesis. Improved understanding of the pathophysiology of spasmodic dysphonia should provide the basis for developing new treatment options and exploratory clinical trials.SignificanceThis document should foster future research to improve the care of patients with this chronic debilitating voice and speech disorder by otolaryngology, neurology, and speech pathology.

PurposeTo review the principles of neural plasticity and make recommendations for research on the neural bases for rehabilitation of neurogenic speech disorders.MethodA working group in speech motor control and disorders developed this report, which examines the potential relevance of basic research on the brain mechanisms involved in neural plasticity and discusses possible similarities and differences for application to speech motor control disorders. The possible involvement of neural plasticity in changes in speech production in normalcy, development, aging, and neurological diseases and disorders was considered. This report focuses on the appropriate use of functional and structural neuroimaging and the design of feasibility studies aimed at understanding how brain mechanisms are altered by environmental manipulations such as training and stimulation and how these changes might enhance the future development of rehabilitative methods for persons with speech motor control disorders.ConclusionsIncreased collaboration with neuroscientists working in clinical research centers addressing human communication disorders might foster research in this area. It is hoped that this article will encourage future research on speech motor control disorders to address the principles of neural plasticity and their application for rehabilitation.