A Functional Magnetic Resonance Imaging Study in Patients with Benign Essential Blepharospasm

Abstract

OBJECTIVE To identify blinking-induced functional magnetic resonance imaging (fMRI) activation patterns in five benign essential blepharospasm (BEB) patients and five age-matched control subjects. METHODS fMRI brain activation maps were obtained during repeated conditions of spontaneous and voluntary blinking in BEB and control groups. Blood oxygen level-dependent intensity images were collected from two separate runs as 16 axial and 16 coronal, 8 mm thick slices using a T2-star weighted gradient echo EPI sequence, coregistered with anatomic images. Spatially normalized and isotropically blurred activation maps for each subject were combined within groups of BEB patients and control subjects to generate maps of the intersubject mean fractional signal change.RESULTS Substantially greater activation during spontaneous and voluntary blinking was seen in BEB patients compared with control subjects in the anterior visual cortex, anterior cingulate cortex, primary motor cortex, central region of the thalamus, and superior cerebellum. In both groups, activations were generally greater for voluntary than for spontaneous blinking. CONCLUSIONS The activations observed might represent a hyperactive cortical circuit linking visual cortex, limbic system, supplementary motor cortex, cerebellum, and supranuclear motor pathways innervating the periorbital muscles.

Structural, functional and molecular imaging of the brain in primary focal dystonia—A review

“…In patients with BLS, Baker et al (2003) found bilateral increased activation of the visual cortex and area prostriata, primary motor cortex, cingulated cortex, posterior putamen, central thalamus, and the superior cerebellar hemispheres and vermis during spontaneous and voluntary blinking in patients with BLS compared to controls. Patients did not experience eyelid spasms during these tasks.…”

“…Generally speaking, tasks that induce focal dystonia usually lead to an increase in activation, whereas tasks that do not induce dystonia lead to a decrease in activation of the above named areas. Other findings that stand out in fMRI studies are activation of the visual and visual association cortices while blinking (Baker et al, 2003;Schmidt et al, 2003), but also during tactile stimulation (Peller et al, 2006), and disorganisation of the hand area on the primary sensory cortex. The latter is especially present in patients with WC and consists of overlap of the areas representing different digits, mainly digits 1-3 (Nelson et al, 2009).…”

Blefaroespasmo essencial: revisão da literatura

“…Alguns autores aplicaram métodos de imagem, como tomografia por emissão de pósitrons (PET) (11) e ressonância nuclear magnética funcional (fMRI) (12)(13) para tentar elucidar os mecanismos envolvidos na fisiopatologia do blefaroespasmo. Schmidt et al (12) realizaram exames de fMRI em 6 pacientes com a doença e em todos eles puderam correlacionar ativação uni ou bilateral do putâmen com os espasmos palpebrais.…”

Animal models of focal dystonia

“…[123][124][125][126][127] There appear to be three general categories of blepharospasm: 1) benign essential blepharospasm, an idiopathic focal dystonia; 2) reflex blepharospasm, a syndrome associated with dopamine depletion; and 3) Bell's palsy associated blepharospasm, a syndrome concomitant with facial palsy. There are animal models that reproduce reflex blepharospasm and benign essential blepharospasm.…”

“…Most imaging studies in both generalized and focal dystonias report that the same brain regions exhibit increased glucose uptake or blood flow. 23,80,85,89,[123][124][125]127,173,174 In virtually all cases of primary dystonia, there is dysfunction of the thalamus, frontal cortex, cerebellum, and basal ganglia, particularly the striatum. These altered activity patterns at least partially reflect a reduction in cortical inhibition.…”