The Influence of Gaze Shift and Emotions on Symptoms of Blepharospasm- a Pilot Study.

Blepharospasm (BEB) is a focal dystonia characterized by forceful, involuntary contractions of the orbicularis oculi muscle. (Jankovic et al 1983) Patients with BEB report task and situation specific modulations of their symptoms. So called "sensory tricks" are actions that minimize symptoms and include concentrating, talking, pulling on the eyelids, blowing air, and applying pressure to the periocular or temple region. (Weiner 1984) Many patients describe that other tasks/situations are exacerbate their symptoms specifically under bright fluorescent lights and stress. (Burke 1984) Earlier studies showed that blink patterns differ between BEB patients and control during rest, reading and talking.

In healthy subjects gaze evoked blinks are a physiologic phenomenon: initiation of gaze shifts evoke a blink, blinks facilitate gaze shifts. (Evinger 1994) In healthy subjects emotions and thoughts influence gaze shifts and blink rate. (Leal 2008, de Genaro 1988) However, little is known about various task and emotion specific influences on symptoms of BEB (e.g. expecting a gaze shift might worsen symptoms while driving a car).

Differences in emotion and gaze related blink patterns between patients and controls will contribute to the understanding of the pathophysiology of BEB. This might offer new therapeutic options, e.g. symptom modulation.

The investigators hypothesize that blink patterns, measured by duration and frequency of pupillary occlusion differ between patients and control, when performing gaze shifts and emotion related blink patterns, measured by duration and frequency of pupillary occlusion differ between patients and controls.

The aim of this pilot trial is to assess differences in gaze evoked and emotion related blink patterns between patients and controls. These differences might contribute to the understanding of the pathophysiology of BEB.