LARYNGOLOGY AND BRONCHOESOPHAGOLOGY: Edited by Jacqui E. Allen
The voice is an interesting thing. At once, the vocal folds are just a passive valve mechanism designed to protect our respiratory tract, and at other times, they are a view to our deepest emotions through speech and song. No other trait so defines humans as our ability to communicate through speech and express our inner thoughts and feelings. And despite the understanding of the physiology of phonation, we still struggle to explain many of the disorders that affect speech and glottic function. We struggle to come up with new ways to facilitate muscle function and to replicate or repair the delicate structure at the margin of the vocal fold. Many organ systems rely on the larynx for functional support and, in turn, several distant organs may affect laryngeal function. Given the valving function that the larynx undertakes due to its unique position within the aerodigestive tract, influenced and controlled by deglutitive forces, it is exposed to repeated trauma from external and internal material. Trying to understand the key events in neural regulation, or development of dysplasia goes to the core of how the larynx functions. Appreciating normal physiology then uncovers pathologic processes and suggests possible treatment targets.
This issue reviews topics across the field of Laryngology. The impact of muscle asymmetry or hyperfunction on otherwise anatomically normal vocal folds is contrasted with the effect on voice when epithelial disease develops. Dysphonia in both cases but with completely different tissues affected and radically different treatment paradigms. Functional voice disorders demonstrate diverse underlying triggers with variable response to current therapies. Recognition of the need for consistent taxonomy and selection criteria, clear outcome measures and long-term evaluation of results will provide more solid ground on which clinicians may design their treatment strategies. The review by Andreassen et al. (pp. 447–452) thoroughly covers this broad area and is positive about current research streams in this evolving field.
It seems increasingly likely that disordered phonatory patterns are a major driver in the development of lesions within Reinke's space. The fact that similar forces may result in slightly different manifestations, for example polypoid change vs. nodule formation indicates that it is more than just physical disruption causing changes. Innate wound healing responses, genetic predispositions, comorbid conditions and age may also affect the development or resolution of benign vocal fold lesions. As Dr. Carroll (pp. 453–458) reports, molecular clues are now also being identified with upregulation of inflammatory markers and alterations of the apoptotic cascade recently reported in benign vocal fold lesions. When one considers this from a wound healing perspective, as discussed in Professor Hirano's (pp. 459–463) manuscript, it makes more sense to base our recommendations for vocal rest on the known and relatively conserved inflammatory response time course. Although larger, controlled studies would be of huge benefit in this area, the molecular appreciation of timeframes for the infiltration of inflammatory cells, release of mediators and upregulation of cellular machinery that remodels the ground substance of the superficial lamina propria offers a bio-plausible starting point for comparison. These ideas and pathways will undoubtedly also unravel pathways in malignant disease development as discussed by Dr. Parker (pp. 464–468). Biopsies in future may define those with molecularly unstable lesions that require greater surgical excision or laser therapy, or those needing intensive or longer-term follow-up. We now need consistency in biomarkers defined for disease states and risk stratification. Translation to treatment protocols is also needed whereby biological predictors of response to treatment can be used to assist in decision making for therapeutic interventions. Does depth of lesion, presence of genetic change or density of vasculature influence response to laser therapy, surgical excision or conservative measures? These questions are being asked now and will help all those treating malignant or potentially malignant disease in future.
Effect on phonation when the larynx is an innocent bystander as in thyroid disease or neurological conditions is also reviewed. Some might argue that muscle tension dysphonia represents a local manifestation of a systemic issue too! The interplay between the glottis and other systems is part of our central homeostatic control. Flow regulation at the glottis ensures we have end-expiratory pressure to keep alveoli inflated, produces airway-clearing cough and moderates air loss during phonatory activities. External compression, damage to the neural supply or diminution of the luminal sensitivity results in perturbation of loop control. Recurrent laryngeal nerve injury following thyroidectomy is common and not only alters glottic competence but also respiratory homeostasis and pulmonary clearance mechanisms. Being cognisant that additional symptomatology including proprioceptive and sensory issues such as globus sensation, may result from changes in motor biomechanics will help understand patient complaints. Dr. Park (pp. 469–474) illustrates this in publishing findings correlating inflammatory thyroid changes with reported globus sensation. In addition, the newly described ‘postthyroidectomy’ syndrome encompasses a group of pharyngolaryngeal symptoms occurring after thyroidectomy in the absence of direct detectable nerve injury. These symptoms include globus sensation, odynophagia, dysphagia and voice changes with no discernible abnormality in perceptual voice measures, or fluoroscopic swallow studies. Although there appears to be a degree of spontaneous resolution over time, it may be important to council patients accordingly preoperatively or in the immediate postoperative period. It remains to be seen whether other interventions such as augmentation, therapy or medication will alter these symptoms.
We also continue to develop understanding of neurolaryngeal disease such as dystonia and tremor. Dr. Richards (pp. 475–489) has summarized the subtle differences in pathophysiology of these conditions that may now lead us to more targeted management strategies. The case for considering vocal tremor a distinct subset of essential tremor is growing, supported by prevalence, presence of vocal tremor in absence of other tremor sites and pathological findings in neuroanatomic studies. Peripherally, reinnervation techniques offer exciting options for management of paralytic disorders of the larynx. This area of research is receiving increased attention with investigative strands examining nonselective and selective reinnervation and both adult and paediatric populations. Fancello et al. (pp. 480–485) summarize the status of published literature and how far we have come in trying to balance the protective and respiratory functions of the glottis with its phonatory action. Long-term outcomes may be particularly important in this field and these studies are awaited with great interest.
Voice, therefore, remains a defining human characteristic and a crucial part of a productive Society given that more than one-third of adults report a voice problem during their lifespan, and in those who use their voice for occupational purposes, there are a mean of 8 days lost from work as a result [1,2]. Understanding the biomechanics of the glottis will continue to expand our therapeutic armamentarium, whilst appreciation of the voice as an instrument and tool is crucial for translating therapy to the end-user. If we cannot talk to our patients about what is not working, we would not be able to talk to them about what is or what can! At the end of the day, it is all about communication.
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1. Barkmeier-Kraemer JM, Patel RR. The next 10 years in voice evaluation and treatment. Semin Speech Lang 2016; 37:158–165.
2. Bhattacharyya N. The prevalence of voice problems in adults in the United States. Laryngoscope 2014; 124:2359–2362.