stimulation for dystonia: constant-current or constant-voltage stimula- tion? A non erandomized study. Eur J Neurol 2014;Epub ahead of print. 2. Cheung T, Nuno M, Hoffman M, et al. Longitudinal impedance variability in patients with chronically implanted DBS devices. Brain Stimul 2013;12:S1935-1961. 3. Bronstein JM, Tagliati M, McIntyre C, et al. The rational driving the evolution of deep brain stimulation to constant-current devices. Neuro- modulation 2014;Epub ahead of print. 4. De Noriega FR, Eitan R, Marmor O. Constant Current versus Constant Voltage Subthalamic Nucleus Deep Brain Stimulation in Parkinson’s Dis- ease. Stereotact Funct Neurosurg 2015;93:114e121. P 2.095. EFFECT OF BILATERAL SUBTHALAMIC DBS ON GAIT IN PATIENTS WITH IDIOPATHIC PARKINSON'S DISEASE Rupam Borgohain 1 , Rukmini Mridula Kandadai 1 , Venkata Padma Vani Kagita 1 , Aneel Kumar Puligopu 2 , Shaik Afshan Jabeen 1 , Meena Angamuthu Kanikannan 1 . 1 Department of Neurology, Nizamis Institute of Medical Sciences, Hyderabad, India; 2 Department of Neurosurgery, Nizams Institute of Medical Sciences, Hyderabad, India Objectives: To assess change in gait in a cohort of patients with idiopathic Parkinson’s disease (PD) after bilateral subthalamic stimulation (DBS). Methods: 60 patients with PD who underwent DBS were included. Pa- tients were evaluated one month before surgery and at least 12 months after surgery with UPDRS 1-4. Results: Mean age was 56.4 ±10.1 years, mean disease duration 10.6 ± 4.4 years. Post surgery average levodopa equivalent dose decreased from 855±367 to 494±260mg/day (p < 0.01) at one year follow up. ‘On’ period improved from 6.7±2.2 to 16.1±2.4 hrs/day post DBS (p < 0.01). Mean UPDRS-III scores in ‘on’ and ‘off’ states improved significantly from 55.4±14.1 and 16.5±8.7 to 32.2±12.5 (42 %) and 11.9±6.2 (31 %) respec- tively. Gait and postural stability subscores remained similar in ‘on’ state but improved significantly in ‘off’ state after surgery (2.5+ 0.9 and 2.3+ 1.0 to 1.5+ 0.9(p<0.0001) and 1.9+ 0.9 (p<0.0001) respectively). Freezing episodes reduced significantly in both on and off states at one year follow up (see fig). The impact of change in rate of STN stimulation was studied in a small subset. Frequency modulation with lower rates (80-100 Hz) seemed to reduce festination while higher frequencies (160-200Hz) improved freezing. Conclusions: DBS improves gait and postural instability markedly in off state while freezing episodes were reduced both in off and on states. Frequency modulation may further help in stabilizing gait. Ă P 2.096. THE EFFECT OF BILATERAL SUB-THALAMIC NUCLEUS DEEP BRAIN STIMULATION (STN-DBS) ON PROSODY OF SPEECH OF PARKINSON’S DISEASE Fatemeh Majdinasab 1 , Seyed Amir Hassan Habibi 2 , Elnaz Ghorbani 3 , Maryam Khoddami 3 . 1 Department of Speech Therapy, Tehran University of Medical Sciences, Tehran, Islamic Republic of Iran; 2 Department of Neurology, Movement Disorder Clinic Rasool Akram Hospital, Iran University of Medical Sciences, Tehran, Islamic Republic of Iran; 3 Department of Speech Therapy, Tehran University of Medical Sciences, Tehran, Islamic Republic of Iran Objectives: The golden standard method to improve motor function of Parkinson’s disease (PD) is bilateral sub-thalamic nucleus deep brain stimulation (STN-DBS), but its effect on speech is still questionable. To investigate impact of this approach on both main part of prosody (perception and expression) of Farsi speaking PD. Methods: Thirteen PD (6 females) with 14.53±3.23 years of duration of disease and 4±3.39 years after surgery, and 8 normal control group eval- uated. Severity and motor performance of PD assessed by Unified Par- kinson's Disease Rating Scale part-III (UPDRS-III) and Persian Profiling Elements of Prosody in Speech-Communication (PPEPS-C) used to survey both part of perception and expression of prosody in all prosody subscales (affect, focus, chunking, turn-end, …). All of evaluation were done in the “on” state of levodopa medication and stimulation. Results: No significant difference observed between prosody of patients and control (in total score of perception and expression and all prosody subscales. No correlation seen between severity (motor performance) and duration of disease with perception and expression of prosody (total score and all prosody subscales). There was positive relation between expression and perception of prosody in PD (p¼0.000) and significant relationship between all of prosody subscales except affect and turn-end. Conclusions: It seems that bilateral STN-DBS may improve prosody in PD patients. Prosody of speech influenced by linguistic factors and different motor control system from other motor performance. References: 1. Martens H, Van Nuffelen G, Cras P, Pickut B, De Letter M, De Bodt M. Assessment of prosodic communicative efficiency in Parkinson's disease as judged by professional listeners. Parkinson's disease. 2011;129310. 2. Xie Y, Zhang Y, Zheng Z, Liu A, Wang X, Zhuang P, et al. Changes in speech characters of patients with Parkinson's disease after bilateral subthalamic nucleus stimulation. Journal of voice : official journal of the Voice Foun- dation. 2011;25:751-758. 3. Tsuboi T, Watanabe H, Tanaka Y, Ohdake R, Yoneyama N, Hara K, et al. Distinct phenotypes of speech and voice disorders in Parkinson's disease after subthalamic nucleus deep brain stimulation. Journal of neurology, neurosurgery, and psychiatry. 2015;86:856-864. P 2.097. THE EFFECT OF DEEP BRAIN STIMULATION OF SUBTHALAMIC NUCLEUS ON COGNITIVE FUNCTIONS IN PARKINSON'S DISEASE e PILOT STUDY Katarzyna Potasz-Kulikowska 1 , Konrad Kulikowski 2 , Agnieszka G orecka- Mazur 3 , Wojciech Pietraszko 1 , Jaroslaw Polak 1 , Anna Krygowska- Wajs 4 . 1 Department of Neurosurgery Jagiellonian University Collegium Medicum, Cracow, Poland; 2 Institute of Psychology Jagiellonian University, Cracow, Poland; 3 Department of Pathophysiology Jagiellonian University Collegium Medicum, Cracow, Poland; 4 Department of Neurology Jagiellonian University Collegium Medicum, Cracow, Poland Objectives: Deep brain stimulation of subthalamic nucleus (STN DBS) is a well established treatment of motor symptoms in Parkinson's disease (PD) patients. However, its effect on cognitive functions still remains unre- solved. The aim of the study was to evaluate cognitive functions in PD patients before STN DBS and 3, 6 and 12 months after STN DBS. Methods: We evaluated cognitive functions and depressive symptoms in 9 patients age 49-68 years, duration of the disease 5-18 years, before STN DBS and 3, 6, 12 months after STN DBS using verbal fluency test (phono- logical and semantic), Trail Making Test A and B (TMT A and B), Montreal Cognitive Assessment (MoCA) and Montgomery and Asberg Depression Rating Scale (MADRS). Results: We have shown a decrease of phonological and semantic verbal fluency 3 and 6 months after STN DBS and an improvement 12 months after STN DBS. TMT A and B scores were better 12 months after STN DBS and we also reported an improvement of depressive symptoms. Conclusions: This study suggests an improvement in psychomotor speed and spatial memory after STN DBS. The decline of phonological and se- mantic verbal fluency occurred in the short term after surgery and might Abstracts / Parkinsonism and Related Disorders 22 (2016) e87ee141 e106