Bilateral pallidal DBS for blepharospasm: A case report and review of the literature

Background:

Deep brain stimulation (DBS) of the globus pallidus internus (GPi) in the treatment of craniocervical dystonia often requires an extended period of stimulation parameter manipulations.

Case Description:

We present a patient suffering from debilitating blepharospasm treated with bilateral DBS of the GPi alongside 7 years of stimulation parameter manipulations and a literature review of comparable patients.

Conclusion:

Our literature review suggests that a patient’s specific dystonic symptoms can guide stimulation parameter manipulations. Further research regarding trends in stimulation parameters being used in the field for different dystonic symptoms may expedite the stimulation parameter manipulation process.

Tricks in dystonia: ordering the complexity

Sensory tricks are various manoeuvres that can ameliorate dystonia. Common characteristics are well known, but their variety is wide, sensory stimulation is not necessarily the critical feature, and their physiology is unknown. To enumerate the various forms of sensory tricks and describe their nature, research findings and theories that may elucidate their neurophysiologic mechanism, we reviewed the literature pertaining to sensory tricks, including variants like motor tricks, imaginary tricks, forcible tricks and reverse sensory tricks. On the basis of this information, we propose a new classification of sensory tricks to include its variants. We highlight neurophysiologic evidence suggesting that sensory tricks work by decreasing abnormal facilitation. We tie this with established dystonia pathogenesis and postulate that sensory tricks decrease abnormally increased facilitation to inhibition ratios in the dystonic brain. It appears worthwhile for patients to search for possible sensory tricks.

The phenomenology of the geste antagoniste in primary blepharospasm and cervical dystonia

The geste antagoniste (GA), a relatively common feature of adult-onset primary dystonia, has been systematically evaluated only in cervical dystonia, but it is still unclear whether its frequency and phenomenology differ among the various forms of focal dystonia. We analysed the frequency, phenomenology, effectiveness, and relationship of the GA with demographic/clinical features of dystonia in a representative clinical series of patients with the two most common forms of adult-onset primary dystonia, blepharospasm (BSP) and cervical dystonia (CD). Clinical data were gathered using a standardized questionnaire, which showed substantial test-retest reliability (kappa = 0.79, P < 0.00001). The frequency of GA was similar among patients with BSP (42/59, 71.2%) and patients with CD (27/32, 84.4%), and in both groups GA showed similar effectiveness in reducing dystonia. The repertoire of GA was heterogenous in both BSP and CD patients, in whom seven BSP-related and five CD-related types of GA were recorded, and a "forcible" type of GA was present in 69% of BSP patients and in 48.1% of CD patients. In our whole patient population, age at dystonia onset was significantly lower among patients reporting a GA compared to those without GA (P = 0.01). GA features shared by BSP and CD predominate over differences, suggesting common mechanisms underlying this phenomenon in the two forms of primary adult-onset dystonia.