Altered Functional Connectivity and Sensory Processing in Blepharospasm and Hemifacial Spasm: Coexistence and...

Area of Science:

• Neuroscience
• Neurology
• Medical Imaging

Background:

• Blepharospasm (BSP) and hemifacial spasm (HFS) are distinct facial hyperkinesias, with differing proposed etiologies (central vs. peripheral).
• Potential overlapping pathophysiologies between BSP and HFS warrant investigation.
• Understanding shared mechanisms could lead to improved diagnostics and therapeutics.

Purpose of the Study:

• To compare brain resting-state functional connectivity (rsFC) and quantitative thermal test (QTT) results between BSP, HFS, and healthy controls (HCs).
• To identify potential shared pathophysiological links between BSP, HFS, and sensory processing deficits.

Main Methods:

• Recruited 12 BSP patients, 11 HFS patients, and 15 HCs.
• Utilized neuropsychiatric evaluations, disease severity questionnaires, QTT, and resting-state functional MRI (rs-fMRI).
• Analyzed rs-fMRI data using seed-based analyses with the CONN toolbox.

Main Results:

• BSP and HFS patients exhibited higher cold detection thresholds (impaired sensory processing) compared to HCs.
• Increased rsFC was observed between the anterior cerebellum network and left occipital regions in BSP and HFS patients versus HCs.
• Impaired QTT cold detection thresholds correlated with increased rsFC between the anterior cerebellar network and the left lingual gyrus across all subjects.

Conclusions:

• Sensory processing dysfunction, detectable by QTT, is present in both BSP and HFS patients.
• Altered functional connectivity involving the anterior cerebellar network and left occipital region (Brodmann area 19) suggests a possible shared pathophysiology.
• Further large-scale longitudinal studies are necessary to validate these findings and explore the proposed shared mechanisms.