INTRODUCTION A functional voice disorder applies to an alteration of voice quality where there is no structural or neurological laryngeal pathology or where the dysphonia is disproportionate to the pathology detected. Nomenclature is problematic in this area and there are many synonymous and similar diagnostic labels in use, including (most commonly) ‘functional dysphonia’ and ‘non-organic dysphonia’. These terms are generic and indicate characteristics of a syndrome rather than a specific diagnosis. Several key authors have defined several subcategories which more accurately reflect the underlying pathogenesis1-4 and these will be discussed below. Functional disorders of the voice represent by far the commonest presentation to voice clinicians, accounting for at least 50 000 new cases per year in the UK.5, 6 The impact of this condition is considerable: it is known to affect communication in all contexts, and is related to impaired personal and work relationships, low self-esteem and reduced quality of life.6-8 In addition, people with functional dysphonia also suffer from increased levels of anxiety, depression and poor general health.6, 9, 10
It is also important to note that there is an overlap between ‘organic’ and ‘functional’ voice disorders and that they do not represent dichotomous disorders.11 A number of benign vocal pathologies (e.g. vocal nodules, oedema of the lamina propria, contact granulations) are attributable to vocal hyperfunction, voice misuse and poor voice technique.12, 13 Similarly, aberrant phonatory physiology viewed on endoscopic examination (e.g. bowing of the
vocal folds, supraglottic constriction) may also be a consequence of vocal hyperfunction and poor technique.12, 13
THEORETICAL PERSPECTIVES Most contemporary authors have accepted that functional disorders of the voice might usefully be divided into two different subcategories: ‘muscle tension’ dysphonia and ‘psychogenic’ dysphonia.