Objective: To quantify modulation of eye closure rates during activities of daily living in individuals with BSP and asymptomatic individuals with and without family history of BSP.

Background: BSP is a type of focal dystonia that affects the muscles surrounding the eyes. Blink rate is modulated during different motor tasks in BSP but also in individuals without BSP [1, 2]. 27% of patients with BSP have at least one first degree relative also affected by BSP [3]. In this study, we investigated the modulation of the rate of eye closure during several activities of daily living in individuals with BSP and asymptomatic individuals with and without family history of BSP.

Method: 37 patients with BSP (BSP group) (29 females, mean age 62.5 ± 8.65), 10 asymptomatic healthy volunteers who have a first degree relative with BSP (RELATIVES group) (4 females, mean age 53.4 ± 19.9) and 25 healthy volunteers who have no first-degree relatives with BSP (HV group) (14 females, mean age 59.6 ± 9.06) were recruited. A standardized video recording was obtained for all participants while they performed ten tasks for 60 seconds. The tasks were: 1. Resting 2. Talking 3. Reading, 4. Peeling an orange, 5. Eating an orange, 6. Counting, ascending order, starting at one, 7. Counting, descending order, steps of seven, starting at one hundred, 8. Typing, 9. Watching television, 10. Chewing gum. Two investigators watched the video and counted the number of eye closures for each task. Within and between group comparisons of eye closure counts were performed.

Results: In the RELATIVES group the rate of eye closure was not significantly different from the BSP group for the majority of the tasks (except watching television, p=0.04), but also not significantly different from the HV (for all tasks). The rate of eye closures in the BSP group compared to HV, was significantly increased in three tasks, rest (p<0.01), reading (p=0.05) and watching television (p<0.01). The rate of eye closure was modulated between tasks in all three groups with peeling an orange (p<0.01), eating an orange (p<0.01), and typing (p<0.01), being the tasks with significantly less eye closure counts compared to resting.

Conclusion: Eye closure rate is modulated during activities of daily living in BSP but not all activities are equally affected. The group of asymptomatic individuals with first-degree relatives with BSP was not as different to the BSP group as the group of asymptomatic individuals without family history of BSP.

References: 1. Bentivoglio, A.R., et al., Analysis of blink rate in patients with blepharospasm. Mov Disord, 2006. 21(8): p. 1225-9.
2. Ferrazzano, G., et al., Writing, reading, and speaking in blepharospasm. J Neurol, 2019. 266(5): p. 1136-1140.
3. Defazio, G., et al., A family study on primary blepharospasm. J Neurol Neurosurg Psychiatry, 2006. 77(2): p. 252-4.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/eye-closure-during-tasks-in-blepharospasm-bsp/