Preferential age-related striatal volume preservation in cervical dystonia

Previous research has shown inconsistent striatal volumetric differences in isolated, idiopathic dystonia. In healthy populations, progressive striatal volume loss occurs with advancing age. We investigated age-related striatal volume in participants with adult-onset cervical dystonia (CD) and other isolated, idiopathic focal dystonias.

High-resolution structural MRI was analyzed in 184 participants (92 focal dystonia: 33 CD, 18 laryngeal, 18 blepharospasm, 10 embouchure, 13 upper-limb; 92 healthy controls). Subcortical volumes (caudate, putamen, hippocampus, amygdala, ventricles) were quantified using FreeSurfer, adjusted for intracranial volume. Linear regression examined age-volume relationships controlling for sex and motion.

CD showed significantly different age-related striatal trajectories versus controls. Putamen [F(1117) = 10.82, p = 0.001, η² = 0.043] and caudate [F(1117) = 5.17, p = 0.025, η² = 0.027] demonstrated significant group × age interactions after FDR correction. CD exhibited volume increases with age (β = + 37.4 mm³/year) while controls showed typical decline (β = -38.2 mm³/year). This pattern was striatum-specific; hippocampus, amygdala, and ventricles showed similar age-related changes between groups (p > 0.8). Other dystonia subtypes demonstrated age-related decline similar to controls. Among dystonias, only CD showed preserved putamen [F(4,78) = 3.11, p = 0.020, η² = 0.048] and caudate [F(4,78) = 3.59, p = 0.010, η² = 0.080] volumes. Disease duration and severity did not correlate with striatal volumes.

Our findings reveal selective preservation of caudate and putamen volume with age that is unique to CD among focal dystonia subtypes. This neuroanatomical distinction suggests different adaptive or pathophysiological mechanisms underlying CD. These results contribute to the conceptualization of both common and heterogeneous neurobiological substrates across dystonia subtypes, highlighting the importance of subtype-specific research approaches to consider age.