Spasmodic Dysphonia: A Review. Part 2: Characterization of Pathophysiology

Abstract

Objective The 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 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). Conclusion The 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 Practice A 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.

Otolaryngologic Symptoms in Multiple Sclerosis: A Review

“…Speech disorders are mainly correlated to demyelinating lesions in the central speech pathways rather than to a peripheral involvement of recurrent nerve 107 ; in particular, these disorders may be observed in case of lesions located in the subthalamic regions 113 and in the periaqueductal area 108 . They mainly follow a progressive weakness of the musculature that can involve all the speech mechanisms and provoke a relevant decrease of verbal communication skills.…”

Validation of the Communicative Participation Item Bank as an Outcome Measure for Spasmodic Dysphonia

“…Spasmodic dysphonia (SD) is a focal dystonia characterized by laryngeal spasms that result in uncontrolled voice breaks during phonation. 1 This voice dysfluency has debilitating effects on a person's ability to communicate and thus negatively impacts their function in both workplace and social environments. 2 The existing treatment of SD is suboptimal, as the current gold standard involves injection of botulinum toxin into the laryngeal musculature.…”

Dystonia: diagnosis and management

“…Spasms may be brief or sustained and may induce narrowing or closure of the eyelids, but of course have no torsional attitude . In the case of laryngeal dystonia, instrumental examination can reveal spasmodic contractions of the vocal folds (abductor or adductor dysphonia), also without overt torsional appearance . In muscle tension dysphonia, instead, the involuntary contractions affect the accessory phonation muscles without necessarily involving the vocal folds.…”