Laboratory Evaluation of Spasmodic Dysphonia

Exploration of potential immune mechanisms in cervical dystonia

BACKGROUND

Although there are many possible causes for cervical dystonia (CD), a specific etiology cannot be identified in most cases. Prior studies have suggested a relationship between autoimmune disease and some cases of CD, pointing to possible immunological mechanisms.

OBJECTIVE

The goal was to explore the potential role of multiple different immunological mechanisms in CD.

METHODS

First, a broad screening test compared neuronal antibodies in controls and CD. Second, unbiased blood plasma proteomics provided a broad screen for potential biologic differences between controls and CD. Third, a multiplex immunoassay compared 37 markers associated with immunological processes in controls and CD. Fourth, relative immune cell frequencies were investigated in blood samples of controls and CD. Finally, sequencing studies investigated the association of HLA DQB1 and DRB1 alleles in controls versus CD.

RESULTS

Screens for anti-neuronal antibodies did not reveal any obvious abnormalities. Plasma proteomics pointed towards certain abnormalities of immune mechanisms, and the multiplex assay pointed more specifically towards abnormalities in T lymphocytes. Abnormal immune cell frequencies were identified for some CD cases, and these cases clustered together as a potential subgroup. Studies of HLA alleles indicated a possible association between CD and DRB1*15:03, which is reported to mediate the penetrance of autoimmune disorders.

CONCLUSIONS

Altogether, the association of CD with multiple different blood-based immune measures point to abnormalities in cell-mediated immunity that may play a pathogenic role for a subgroup of individuals with CD.

Thyroid disease in cervical dystonia

There are many possible etiologies for cervical dystonia (CD), but a cause cannot be identified in most cases. Most recent attention has focused on genetic causes, although a few prior studies have highlighted autoimmune mechanisms instead. Because autoimmune disorders frequently co-exist, the current study evaluated the hypothesis that autoimmune disorders might be more common in CD than neurological controls. The frequency of 32 common autoimmune disorders was evaluated using a systematic survey comparing 300 subjects with CD with 391 neurological controls. The frequency of thyroid disease was significantly higher in CD (20%) compared with controls (6%). Regression analyses that accounted for age and sex revealed an odds ratio of 4.5 (95% CI 2.5-8.1, p < 0.001). All other autoimmune disorders occurred with similar frequencies in CD and controls. Although these studies do not establish a mechanistic link between CD and autoimmune disease, they suggest the need for further attention to a potential relationship, and more specifically with thyroid disease.

How can we make better decisions about dystonic voice management?

PURPOSE OF REVIEW

The optimal diagnosis and management of dystonic voice disorders are rooted in the nuanced understanding of their phenomenology. Distinguishing between subtypes of vocal dystonia is challenging, not only because the audible and physical presentations of these dystonia's can seem similar, but also because there is a lack of scientific consensus regarding the diagnostic criteria for these conditions. To help improve the clinician's acumen we focus on outlining the classification of the top three neurological voice disorders, notably: spasmodic dysphonia, (2) spasmodic dysphonia with tremor, and essential tremor of the voice. We also provide an algorithmic approach based on current evidence-based literature to guide practitioners through the clinical diagnosis and management of each possible etiology.

RECENT FINDINGS

Much remains unknown about the subtypes of vocal dystonia, and this gap in our knowledge likely limits our ability to advance clinical management. Still, continued experience evaluating and treating these patients yields refined clinical evaluations and decision making.

SUMMARY

Improvements in our clinical decision-making can be made by acknowledging that our limited understanding of vocal dystonia may hinder what therapeutic interventions we can offer, yet our ability to accurately diagnose the dystonia is central to providing optimal patient management.

Do Laryngologists and General Otolaryngologists Manage Laryngopharyngeal Reflux Differently?

OBJECTIVE

To investigate current practices of laryngologists and non-laryngologists in management of Laryngopharyngeal Reflux (LPR).

METHODS

An online survey was sent to members of otolaryngology societies about LPR, and subgroup analysis was performed between laryngologists and non-laryngologists. This survey was conducted by the LPR Study Group of Young Otolaryngologists of the International Federation of Otolaryngological Societies.

RESULTS

A total of 535 otolaryngologists completed the survey. Among them, 127 were laryngologists and 408 were non-laryngologists. Collectively, symptoms most commonly attributed to LPR are cough after lying down/meal, throat clearing, and acid brash; most common findings are thought to be arytenoid erythema and posterior commissure hypertrophy. Respectively, 12.5% and 5% of non-laryngologists and laryngologists believe that ≥50% of LPR patients suffer from heartburn (P = .010). Non-laryngologists are more aware about some extra-laryngeal findings associated with LPR (eg, pharyngeal erythema) than laryngologists. Neither laryngologists nor non-laryngologists associated development of benign lesions of the vocal folds with reflux. The management of LPR substantially differs between groups, with laryngologists indicating increased awareness of (impedance)-pH monitoring as well as the prevalence and treatment of nonacid/mixed LPR. Conversely, non-laryngologists are much more likely to include gastroenterology referral in their management of presumed LPR. Respectively, 44.8% and 27.6% of non-laryngologists and laryngologists believe themselves not sufficiently knowledgeable about LPR.

CONCLUSIONS

Significant differences exist between laryngologists and non-laryngologists in diagnosis and treatment of LPR. Overall only one-third of responders believe themselves to be sufficiently educated about LPR.

LEVEL OF EVIDENCE

4 Laryngoscope, 130:E539-E547, 2020.