Clinical Research Directory

DaxibotulinumtoxinA Injection for Treatment of Adductor Spasmodic Dysphonia

Spasmodic Dysphonia (SD) is a neurologic condition causing inappropriate contraction of the laryngeal musculature, leading to abnormal voicing. The three types (adductor, abductor, and mixed) affect varying muscle groups which produce characteristic voice patterns. The vast majority of patients with SD have adductor type, which impacts the lateral cricoarytenoid and thyroarytenoid muscle complex. While many treatment modalities have been investigated, the most effective treatment is botulinum toxin injection to these muscle groups, performed transcervically with or without electromyography (EMG) guidance. Patients undergoing this treatment typically require re-injection every 3 months. Due to its specialized nature, the laryngeal injections are not performed routinely outside of academic medical centers; thus, patients may come from a distance to receive this treatment. Both due to the significant impact on voice quality when the injections wear off and the sometimes challenging access to treatment, a longer-acting agent is desired. Injectible daxibotuliumtoxinA (DAXI, Revance Therapeutics Inc., Newark, CA) has been shown in large clinical trials to provide safe, effective treatment for glabellar lines and cervical dystonia and may offer a longer-lasting result when compared with onabotulinumtoxinA. Thus, a study examining the effect of DAXI for patients with adductor spasmodic dysphonia is proposed. This study aims to assess the efficacy of DAXI for transcervical laryngeal injection in patients with adductor spasmodic dysphonia.

The 'Lombard Effect' in Patients Affected by Adductor Laryngeal Dystonia

Adductory spasmodic dysphonia (AdSD) is a rare condition characterised by irregular and uncontrolled voice interruptions, most commonly affecting women around the age of 45. The diagnosis is clinical and usually requires evaluation by several specialists. The exact cause is not known, but a disturbance of the motor system is hypothesised, probably related to various causes such as loss of cortical inhibition or problems with sensory input. Neuroimaging studies have shown hyperactivity in various brain regions during speech production in patients with AdSD, but it is still unclear whether this hyperactivity is due to a malfunction of auditory and somatosensory feedback or an impairment of motor programming. Recent research indicates that patients with AdSD show excessive muscle activation during phonation, probably due to abnormal processing of auditory feedback. This suggests that intervention in the auditory system may offer new treatment opportunities. The proposed study aims to describe the acoustic, auditory-perceptual and subjective voice and speech changes in AdSD subjects during the Quick-Lombard Test (LT), a test that assesses vocal response under noisy conditions.