EP 10. Pallidal stimulation affects speech fluency in dystonia

Abstract

Introduction Deep brain stimulation (DBS) of the globus pallidus interna (GPi) used in treatment of pharmacoresistant dystonic syndromes is potentially accompanied by several side effects including disorders of speech. Stuttering-like dysfluencies appeared with basal ganglia dysfunction and were occasionally reported as a consequence of GPi DBS in a few cases with dystonia ( Nebel et al., 2009) . Objectives To study possible deterioration of speech fluency after GPi DBS. Patients and methods Speech fluency was systematically evaluated in 19 patients (12 women, 7 men, aged 48 ± (SD)18 years) with dystonia of various origin (14 idiopathic, 2 DYT-1, 2 with parkinsonism, 1 post-anoxic) and distribution (11 generalized and 8 cervical) treated with GPi DBS bilaterally (disease duration 14 ± 6 years, 10–81 months after implantation). Each patient was tested in two conditions within the same day: in the DBS chronically switched on (ON condition) and two hours after switching the DBS off (OFF condition). All patients performed monologue for approximately 90 sec on a given topic. Analysis of dysfluency was performed according to the behavioral taxonomy of stuttering, where the percentage of dysfluent words was calculated as the number of dysfluent events normalized by the total number of words within entire monologue. Repeated measures analysis of variance was applied to count differences in speech fluency between ON and OFF conditions. Results Analysis revealed significant decrease of dysfluent words in OFF condition (3.4 ± 1.7%) to ON condition (2.3 ± 1.6%) in dystonia patients (p Conclusion These findings emphasize a role of the GPi in regulating speech fluency and generally support the view of stuttering as a speech disorder of basal ganglia origin. Whether this side effect of GPi DBS in dystonia may compromise quality of verbal communication it remains to be specified. Supported by the grants of the Czech Ministry of Health ( IGA MZ CR NT12282-5/2011 and MZ CR 15-28038A ).