Blepharospasm and the modulation of cortical excitability in primary and secondary motor areas

Abstract

Background: Traditionally, benign essential blepharospasm (BEB) is considered a disorder caused

Transcranial magnetic brain stimulation modulates blepharospasm

“…To stimulate the ACC, in a previous study, we used stimulation intensities based on the motor threshold of the OO muscle (we stimulated with 90% resting motor threshold of the OO, which was 60.6% stimulator output). 10 In this study, we used the tibialis anterior muscle to determine stimulation intensity due to practical reasons. Determining the active motor threshold in the OO is generally possible, but much more elaborate and sometimes bothersome for the patient.…”

The blink reflex recovery cycle differs between essential and presumed psychogenic blepharospasm

“…[12][13][14] It is normal in patients with apraxia of eyelid opening. 15,16 We hypothesized that patients with atypical (presumed psychogenic) blepharospasm would have a normal blink reflex recovery curve and therefore differ from BEB.…”

Resolution of blepharospasm after chronic subdural haematoma evacuation: A case report

“…As our patient had marked brain shift and compression due to the CSDH evident in the CT scan, it is very likely that the mechanical pressure on the basal ganglia, either directly from the overlying haematoma or indirectly by displacement and pressure on the brain substance was the cause for blepharospasm. Additional infl uencing factors may involve circulatory disturbances caused by increased intracranial pressure and compression of the anterior choroid artery, supplying the basal ganglia [3,8]. We propose another mechanism for blepharospasm development in our patient.…”

“…Pressure on the cortex may thus increase intracortical facilitation of certain motor neuron groups and inhibit the other motor areas [8,9]. Some neuronal connections from the cortex run also through the anterior part of the cingulate gyrus, which is directly or indirectly associated with the essential blepharospasm [8]. It may therefore be possible, that in our patient the cortical irritation caused facilitation of the neurons, supplying through the striate and thalamus the nuclei of the facial muscles, causing the blepharospasm.…”

“…As the haemiparesis was not very expressed, it is likely that changes in the discharge of the cortical neurons due to pressure of the haematoma affected the cortical-striate-thalamic pathway and that this was the reason for the blepharospasm. Pressure on the cortex may thus increase intracortical facilitation of certain motor neuron groups and inhibit the other motor areas [8,9]. Some neuronal connections from the cortex run also through the anterior part of the cingulate gyrus, which is directly or indirectly associated with the essential blepharospasm [8].…”