Phenotypic differences in spasmodic dysphonia arise at the level of the primary and associative areas of motor control, whereas genotype-related pathophysiological mechanisms may be associated with dysfunction of regions regulating phonological and sensory processing, a recent study found. Identification of structural alterations specific to disorder phenotype and putative genotype provides an important step toward future delineation of imaging markers and potential targets for novel therapeutic interventions for spasmodic dysphonia. 89 patients with spasmodic dysphonia underwent high-resolution magnetic resonance imaging and diffusion-weighted imaging to examine cortical thickness and white matter fractional anisotropy in adductor vs abductor forms (distinct phenotypes) and in sporadic vs familial cases (distinct genotypes). Researchers found:
- Phenotype-specific abnormalities were localized in the left sensorimotor cortex and angular gyrus and the white matter bundle of the right superior corona radiata.
- Genotype-specific alterations were found in the left superior temporal gyrus, supplementary motor area, and the arcuate portion of the left superior longitudinal fasciculus.
Bianchi S, Battistella G, Huddleston H, et al. Phenotype- and genotype-specific structural alterations in spasmodic dysphonia. [Published online ahead of print February 10, 2017]. Mov Disord. doi:10.1002/mds.26920.