The aim of our study was to compare the connectivity between large-scale resting state networks and the cerebellum before and after treatment initiation.

Administration of botulinum neurotoxin A (BoNT) injections is currently the preferred, although symptomatic, treatment of focal dystonia. The clinical effect of BoNT is assumed to be mediated by dynamic changes at multiple levels of the sensorimotor system. Recently, the role of the cerebellum in the pathophysiology of dystonia has been discussed. The aim of our study was to compare the connectivity between large-scale resting state networks and the cerebellum before and after treatment initiation.

Twelve patients with cervical dystonia indicated for treatment with BoNT were enrolled (11 female, aged 50.8 ± 8.1 years, range 38-61 years). Clinical and functional MRI examinations were carried out immediately before and 4 weeks after BoNT injection. Clinical severity of dystonia was evaluated using the TWSTRS. The functional imaging data were acquired using a 1.5 Tesla MRI scanner during an 8-minute rest. Pre-processed data from both sessions were decomposed into 30 group-wise independent components (IC's) using MELODIC from the FSL toolbox. Treatment-related changes in connectivity between the cerebellum and the whole-brain components were evaluated using dual regression analysis and non-parametric permutation testing.

Clinical scoring demonstrated satisfactory clinical effect of BoNT. The only significant difference was detected in the left-sided fronto-parietal component (IC 7, Figure 1), which demonstrated a decrease of functional connectivity after the treatment in the left cerebellar lobule VIIIa (coordinates [x,y,z]: -34, -54, -56).

Our data provide evidence for abnormal resting state connectivity between large-scale cortical networks and the cerebellum.

Research was supported by grant of the Agency for Healthcare Research of the Czech Republic (AZV MZ CR) NV16-30210A and Institutional Support of Research Organization MZ CR RV FNOL 2017. All rights reserved.