Blepharospasm is a focal dystonia characterized by involuntary eyelid closure. 1 Sensory tricks are sensory stimuli used by patients with dystonia to transiently reduce spasms. Herein we describe a patient of blepharospasm who used an Indian turban as a sensory trick.
A 41-year-old forest guard presented with a 2-year history of upper limb tremors and nonprogressive involuntary closure of both eyes. Initially he had difficulty opening his eyes but since the past 18 months he noticed that merely touching his upper eyebrows would help him open his eyes (Segment 1). At his work, he was required to wear a cap resembling a baseball cap and he observed that the blepharospasm improved by 25% when the cap covered his eyebrows (Segment 2). He accidentally realized that when he wore a turban at home it was easier for him to open his eyes without having to touch his eyebrows (sensory trick). The trick of touching his right supraorbital ridge improved his blepharospasm by ϳ30% after which he could write and read (Segment 3). Interestingly, he had no improvement on touching his left supraorbital ridge. At baseline, he rated the severity of his blepharospasm using the Visual analogue scale (VAS) as "10 " and this improved after wearing a turban to "6. " On the verbal scale he reported that his symptoms were "severe " without a turban and they were "mild" after wearing a turban. He had no exposure to neuroleptics. His extraocular muscle movements were normal. He had left sided bradykinesia, rigidity, and rest tremors, and we diagnosed him as Parkinson's disease (Hoehn and Yahr Stage1).
The mechanism of sensory tricks in blepharospasm is unknown. In some patients applying contact over the specific site can transiently reduce the intensity of the spasms and so that they can carry on with their tasks with less interference from the unwanted muscular activity. 2 Furthermore, studies have shown that the stimulus intensity modifies the blink reflex recovery rate in humans. 3 Animals models to explain the focal dystonia have shown that the dysfunctional sensorimotor integration in which the nervous system misinterprets sensory signals or misinterprets the desired movement. 4 Patients who used a sensory trick had a normal prepulse inhibition while those who did not had no such inhibition suggesting that abnormalities in sensory gating mechanism are a consequence rather than a cause for the dystonia. 5 This is further strengthened by the fact that in some patients sensory gating mechanisms are likely amenable to adaptation and learning. The effective modulation of the sensory gating perhaps causes reorganization in the neuronal reflex circuits. Our Patient used the Indian turban, an everyday headgear, as an effective sensory trick, highlighting the fact that sensory gating mechanisms are perhaps amenable to adaptation and learning.