Abstract
IntroductionBlepharospasm is characterized by involuntary eyelid spasms. It can be associated with perioral dystonia (Meige's syndrome or orofacial dystonia). We aimed at studying resting‐state functional brain connectivity in these patients and its potential modulation by therapeutic botulinum toxin injections.MethodsWe performed resting‐state functional MRI and a region of interest‐based analysis of functional connectivity in 13 patients with blepharospasm/Meige's syndrome in comparison to 13 healthy controls. Patients were studied before and 4 weeks after botulinum toxin treatment. Simultaneous facial electromyography was applied to control for involuntary facial movements.ResultsBefore botulinum toxin treatment, patients showed reduced functional connectivity between caudate and primary sensorimotor, somatosensory association and visual cortices as well as between putamen and parietal association cortex. Cerebellar areas displayed decreased functional connectivity to somatosensory and visual association cortices. On the cortical level, connectivity was reduced between the cingulate cortex and the primary sensorimotor/premotor and parietal association cortex, between premotor areas and the primary somatosensory cortices, and between the postcentral gyrus and temporoparietal, secondary somatosensory, cingular, and cerebellar regions. Botulinum toxin treatment modulated functional connectivity, especially between cerebellum and visual cortices.ConclusionsPatients with blepharospasm/Meige's syndrome show altered functional connectivity at rest in widespread brain regions including basal ganglia, cerebellar, primary/secondary sensorimotor, and visual areas. Functionally, this may reflect a predisposition for defective movement inhibition and sensorimotor integration. Botulinum toxin treatment could modulate brain connectivity in blepharospasm by altering visual and sensory input.
Highlights
Blepharospasm is characterized by involuntary eyelid spasms
Functional magnetic resonance imaging showed a reduced activation of the primary motor and ventral premotor cortex during an oral motor task in orofacial dystonia (OFD) patients compared to healthy controls (HCs) and to patients with isolated blepharospasm
Patients with blepharospasm or mild OFD showed a widespread pattern of altered FC in connections from and to basal ganglia, primary and secondary sensorimotor cortices, parietal association cortices, visual areas, and cerebellum
Summary
Blepharospasm is a focal dystonia with involuntary bilateral eyelid spasms and increased blinking rate. Functional magnetic resonance imaging (fMRI) showed a reduced activation of the primary motor and ventral premotor cortex during an oral motor task in OFD patients compared to healthy controls (HCs) and to patients with isolated blepharospasm. Others found enhanced activation of anterior cingulate cortex, primary motor cortex, thalamus, and cerebellum during voluntary blinking in blepharospasm patients (Baker, Andersen, Morecraft, & Smith, 2003). Together, these findings were interpreted in the context of impaired (cortical) inhibition and changes in somatosensory representations in analogy to previous findings in other forms of focal dystonia (Neychev, Gross, Lehericy, Hess, & Jinnah, 2011). Simultaneous electromyographic (EMG) recording was applied to control for involuntary facial movements during MRI
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