Objective: In this study, we aimed to assess structural connectivity alterations in the basal ganglia, thalamus and cerebellum in patients with idiopathic blepharospasm (BS) compared to healthy controls. We hypothesised that motor network dysfunction is likely to play a role in the neuropathology of primary dystonia.

Background: Isolated adult-onset focal dystonia is considered to be a motor network disorder, with dysfunction of the basal ganglia and cerebellar circuits contributing to the pathophysiology.

Method: Diffusion Tensor Imaging (DTI) with 3-Tesla MRI was employed to evaluate microstructual alterations in structural connectivity in 9 patients with idiopathic BS (mean age: 65.6±10.0 years; 3 males (33.3%), 6 females (66.7%); mean disease duration: 9 years) compared with 18 age- and gender-matched healthy controls (mean age: 67.4±8.5 years; 7 males (38.9%), 11 females (61.1%). Using an a priori region-of-interest approach, we assessed and compared local alterations in fractional anisotropy (FA) and mean diffusivity (MD) between patients with idiopathic BS and healthy controls in order to determine disease-specific patterns of white matter abnormalities.[1].

Results: Patients with idiopathics BS exhibited increased FA (P=0.025) and reduced MD (P<0.001) in the putamen compared to the group of healthy controls. Patients with idiopathics BS had reduced MD in the caudate (P=0.016), globus pallidus (P<0.001), thalamus (P=0.005), substantia nigra (P<0.001) and cerebellum (P<0.001) compared to the group of healthy controls.

Conclusion: Our pilot data demonstrate that idiopathic BS is associated with patterns of altered white matter microstructural connectivity within regions of the basal ganglia and cerebellum. These findings support the notion that microstructural changes within the basal ganglia and cerebellar motor circuits could underlie the manifestation of focal dystonia, however we anticipate the analyses of additional idiopathic BS subjects in order to draw more definite conclusions.

References: 1)Tondo G, Esposito M, Dervenoulas G, Wilson H, Politis M, Pagano G. Hybrid PET-MRI Applications in Movement Disorders. Int Rev Neurobiol. 2019;144:211-257

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MDS Abstracts - https://www.mdsabstracts.org/abstract/microstructural-changes-in-basal-ganglia-and-cerebellar-networks-in-patients-with-idiopathic-blepharospasm/