Video analysis of patients with blepharospasm and lower face dystonias

Background: Blepharospasm (BSP) is a focal dystonia. There is a lack of standardization in the length of time necessary to get a measure of BSP severity for rating scales.Objectives: 1) Determine the difference between evaluating the number of eye closures in patients with blepharospasm in 1 vs. 2 min. 2) Characterize the prevalence, phenomenology and concordance of sensory trick in subjects with only blepharospasm compared to those with blepharospasm associated with other dystonias of the head.Methods: Thirty-eight, 2-min-long standardized videos of subjects with BSP without any other dystonias were reviewed (group1). Eye closure rate was measured in 0–60 s vs. 60–120 s. Wilcoxon signed-rank test and Spearman correlation coefficient were used to compare the eye closure rate between these two intervals. An additional 68 standardized videos of subjects with blepharospasm associated with dystonia of the head were reviewed (group2). Presence, phenomenology and concordance between what subjects verbally reported as their sensory trick and what they demonstrated was classified for both groups then qualitatively compared.Results/conclusion: Eye closure rates between 0–60 s and 0–120 s were not statistically different. There is no added benefit of counting the number of eye closures in 2 min, compared to 1 min, in patients with BSP. Sensory trick was reported by 57% of subjects with BSP and 80% of subjects who have blepharospasm and other dystonias of the head. With 100% and 97% concordance, patients’ self-reported sensory trick accurately describes the movements that alleviate their dystonic movements

Sensory Attenuation Assessed by Sensory Evoked Potentials in Functional Movement Disorders.

BACKGROUND: Functional (psychogenic) movement disorders (FMD) have features associated with voluntary movement (e.g. distractibility) but patients report movements to be out of their control. One explanation for this phenomenon is that sense of agency for movement is impaired. The phenomenon of reduction in the intensity of sensory experience when movement is self-generated and a reduction in sensory evoked potentials (SEPs) amplitude at the onset of self-paced movement (sensory attenuation) have been linked to sense of agency for movement. METHODS: We compared amplitude of SEPs from median nerve stimulation at rest and at the onset of a self-paced movement of the thumb in 17 patients with FMD and 17 healthy controls. RESULTS: Patients showed lack of attenuation of SEPs at the onset of movement compared to reduction in amplitude of SEPs in controls. FMD patients had significantly different ratios of movement onset to rest SEPs than did healthy controls at each electrode: 0.79 in healthy controls and 1.35 in patients at F3 (t = -4.22, p<0.001), 0.78 in healthy controls and 1.12 at patients C3 (t = -3.15, p = 0.004) and 0.77 in healthy controls and 1.05 at patients P3 (t = -2.88, p = 0.007). CONCLUSIONS: Patients with FMD have reduced sensory attenuation as measured by SEPs at onset of self-paced movement. This finding can be plausibly linked to impairment of sense of agency for movement in these patients