Objective: To study the microstructural changes and functional connectivity in cranial, cervical, and cranio-cervical segmental dystonia using voxel-based morphometry (VBM), diffusion tensor imaging (DTI), and resting-state functional magnetic resonance imaging (fMRI).

Background: The rapid advances in neuroimaging techniques have shown that isolated focal dystonia is not a disorder due to isolated brain lesions but involves damage in multiple brain networks. Microstructural abnormalities within the brain and abnormal functional connectivity (FC) between multiple areas of the brain support the view that dystonia is a network disorder.^1,2

Method: A total of 42 patients (cranial=14, cervical=14, and cranio-cervical=14) and 14 healthy volunteers (HV) were included in the study between January 2019 to December 2020. Voxel-based morphometry (VBM), DTI, and resting-state fMRI were used to assess grey matter volume, white matter damage, and resting brain connectivity respectively. Correlations between diffusion measures, dystonia severity and duration of illness, and duration of botulinum toxin were tested.

Results: VBM study displayed widespread grey matter atrophy in cranial and cranio-cervical segmental dystonia groups. An excess of grey matter in the anterior part of the cerebellum was demonstrated in cervical dystonia. DTI study showed widespread white fiber atrophy in all three groups. The microstructural abnormalities were predominant in the left cerebral hemisphere. There was a negative correlation of fractional anisotropy value in forceps minor with the duration of illness in cranial dystonia. There was a positive correlation of mean diffusivity (MD) value in bilateral anterior thalamic radiations with the duration of botulinum toxin in cranial dystonia and in left uncinate fasciculus with the Burke‐Fahn‐Marsden Dystonia Rating Scale score in cervical dystonia. The resting-state fMRI showed increased functional connectivity in cervical dystonia.

Conclusion: The pattern of brain involvement in cervical dystonia is different from other dystonia in our study. There is increased cellular density and network connectivity in cervical dystonia. There is left hemispheric predominance in the majority of results in all the 3 dystonia groups. These significant findings may have therapeutic implications like deep brain stimulation in cranio-cervical dystonia.

References: 1. Berman BD, Honce JM, Shelton E, Sillau SH, Nagae LM. Isolated focal dystonia phenotypes are associated with distinct patterns of altered microstructure. Neuroimage Clin. 2018 Jun 5; 19:805-812. 2. Jochim A, Li Y, Gora-Stahlberg G, Mantel T, Berndt M, Castrop F, Dresel C, Haslinger B. Altered functional connectivity in blepharospasm/orofacial dystonia. Brain Behav. 2017 Dec 18;8(1): e00894.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/a-study-of-microstructural-changes-and-functional-connectivity-in-cranial-cervical-and-cranio-cervical-segmental-dystonia-by-multimodal-mri/