By Harini Sarva, MD
Assistant Professor of Clinical Neurology, Weill Cornell Medical College
Dr. Sarva reports no financial relationships relevant to this field of study.
SYNOPSIS: Researchers demonstrated that isolated laryngeal dystonia in an Italian population can spread to contiguous regions, thus expanding knowledge of dystonia spread and phenomenology of this rare form of dystonia.
SOURCE: Esposito M, Fabbrini G, Ferrazzano G, et al. Spread of dystonia in patients with idiopathic adult-onset laryngeal dystonia. Eur J Neurol 2018;25:1341-1344.
Spread of focal dystonia has been described with limb dystonia, cervical dystonia, and blepharospasm. However, the frequency of spread of laryngeal dystonia has not been well described because of mixed population reports. This retrospective study of laryngeal dystonia obtained from the Italian Dystonia Registry reported that of 71 adults with laryngeal dystonia, 79% were women, the mean age of dystonia onset was in the sixth decade, and 84% had the adductor form of laryngeal dystonia.
Fifty subjects had focal laryngeal onset. Among the other 21 subjects, eight had onset in the cranial region, 10 in the neck, and three in the upper limb, with spread to the larynx. Among the fifty with laryngeal onset, 32% spread to a contiguous body region (11 to the neck and five to cranial regions). Thirty-four continued to have isolated laryngeal dystonia over a long period of follow-up, ranging from one to 56 years. For those whose dystonia spread from the larynx, contiguous regions were affected within the first year of dystonia onset. In general, when found in those with other body parts affected, laryngeal dystonia was found most commonly with cervical dystonia and less commonly with upper limb dystonia. None were DYT-1 positive.
COMMENTARY
Adult-onset laryngeal dystonia is a rare form of isolated, action-specific dystonia. When it occurs, it affects women more commonly and begins in the sixth decade. Adductor spasm is the most common form. Esposito et al reviewed data from a large dystonia registry comprising subjects from 37 institutions in Italy. The results provide insight into the frequency of spread as well as common phenomenology, allowing clinicians to better counsel patients regarding dystonia spread. However, since participants were from a single ethnic population, it may be difficult to extrapolate these results to other ethnic populations. In addition, all subjects were referred by movement disorders centers; thus, referral bias is an issue. In addition, other dystonia genes known to cause laryngeal dystonia, such as THAP1, TUB4, and GNAL, were not tested. As clinical variability is common among the genetic dystonias, not knowing the complete genetic results further limits the generalizability of these results. Adult-onset laryngeal dystonia can spread to contiguous body regions, but further study is needed to confirm this observation in other ethnic populations as well as in genetically confirmed DYT-1 isolated dystonias.
