Abstract
In clinical practice, involuntary vocalizing behaviors are typically associated with Tourette syndrome and other tic disorders. However, they may also be encountered throughout the entire tenor of neuropsychiatry, movement disorders, and neurodevelopmental syndromes. Importantly, involuntary vocalizing behaviors may often constitute a predominant clinical sign, and, therefore, their early recognition and appropriate classification are necessary to guide diagnosis and treatment. Clinical literature and video-documented cases on the topic are surprisingly scarce. Here, we pooled data from 5 expert centers of movement disorders, with instructive video material to cover the entire range of involuntary vocalizations in humans. Medical literature was also reviewed to document the range of possible etiologies associated with the different types of vocalizing behaviors and to explore treatment options. We propose a phenomenological classification of involuntary vocalizations within different categorical domains, including (1) tics and tic-like vocalizations, (2) vocalizations as part of stereotypies, (3) vocalizations as part of dystonia or chorea, (4) continuous vocalizing behaviors such as groaning or grunting, (5) pathological laughter and crying, (6) vocalizations resembling physiological reflexes, and (7) other vocalizations, for example, those associated with exaggerated startle responses, as part of epilepsy and sleep-related phenomena. We provide comprehensive lists of their associated etiologies, including neurodevelopmental, neurodegenerative, neuroimmunological, and structural causes and clinical clues. We then expand on the pathophysiology of the different vocalizing behaviors and comment on available treatment options. Finally, we present an algorithmic approach that covers the wide range of involuntary vocalizations in humans, with the ultimate goal of improving diagnostic accuracy and guiding appropriate treatment. © 2019 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.
Highlights
An extraordinary cause of belching was seen in a patient with parkinsonism, who suffered from a disturbance of esophageal motility with consecutive belching during OFF-periods that remitted with levodopa intake.[189]
We here presented the wide range of involuntary vocalizations in humans, together with 29 video-documented cases to exemplify their phenomenology
Based on these cases and on the extensive literature review, we provide a diagnostic algorithm to guide clinicians in approaching patients with involuntary vocalizing behaviors (Fig. 1), discuss their pathophysiology, and provide treatment options, where available
Summary
Medical literature and clinical practice have historically associated abnormal vocalizing behaviors with tic disorders, as for example, Tourette syndrome (TS), of which they are an essential part of the diagnostic criteria.[3]. In many of these disorders, abnormal vocalizations will often be only one feature of a range of abnormal motor behaviors and clinical signs, in some cases, they may constitute the sole clinical finding. Their early recognition and appropriate classification are paramount for guiding diagnostic reasoning and informing therapeutic decisions. Given the difficulties in the phenomenological classification of vocalizing behaviors, we here provide a clinical overview of the range of involuntary vocalizations in humans, together with 29 informative video-documented cases, to illustrate both typical and more unusual clinical examples. Our goal is to inform our colleagues from the neighboring fields of neurology, neuropsychiatry, and psychiatry on the phenomenological spectrum and diagnostic conditions associated with involuntary vocalizations, discuss their pathophysiology, and provide treatment recommendations where possible
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