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Objective: Gait disturbances are frequent side effects occurring during chronic thalamic deep brain stimulation (DBS) in patients with essential tremor (ET). Adapting stimulation settings to shorter pulse widths has been shown to reduce side effects of subthalamic DBS. Here, we assess how a reduction of pulse width changes gait performance of affected patients., Methods: Sensor-based gait assessment was performed to record spatiotemporal gait parameters in 10 healthy subjects (HS) and 7 patients with ET with gait disturbances following thalamic DBS. Patients were tested during standard DBS, after 72 hours of stimulation withdrawal and at least 30 days after adjusting DBS settings to a shorter pulse width of 40 µs (DBS40PW)., Results: Patients with ET on standard DBS showed significantly higher variability of several spatiotemporal gait parameters compared with HS. Variability of stride length and range of motion of the shanks significantly decreased OFF DBS as compared with standard DBS. This improvement was maintained over 30 days with DBS40PW while providing effective tremor suppression in six out of seven patients., Conclusion: Shorter pulse widths may reduce gait disturbances in patients with ET that are induced by DBS while preserving a level of tremor suppression equal to standard stimulation settings., Competing Interests: Competing interests: DK, SE and A-CM declare no competing interests or financial dependencies. AK received honoraria from Medtronic, Boston Scientific and St Jude Medical, is member of an advisory board for Boston Scientific, received a travel grant from Boston Scientific, and received a research grant from Medtronic., (© Author(s) (or their employer(s)) 2019. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: Deep brain stimulation (DBS) has proven to be a safe and effective therapy for refractory essential tremor, but information regarding long-term outcomes is lacking., Objectives: We aimed to assess the long-term safety and efficacy of DBS in patients with essential tremor., Methods: Patients treated with DBS for essential tremor for at least 8 years were evaluated in the 'on' and 'off' state using the Fahn-Tolosa-Marin tremor rating scale, and their medical records were reviewed to assess complications related to this therapy., Results: We studied 13 patients (7 men): median age at evaluation 79 years (range 47-88), median age at electrode implantation 68 years (range 37-78) and mean time since electrode implantation 132.54±15.3 months (range 114-164). The difference between the 'off' and 'on' state on the motor items of the tremor rating scale was 41.9% (58.62 vs. 34.08, p<0.001) in the non-blinded and 37.2% (56.07 vs. 35.23, p<0.001) in the blinded rating. DBS provided a functional improvement of 31.7% in the 'on' state (15.07 vs. 22.07, p<0.001). A total non-blinded improvement in the tremor rating scale of 39% was observed in the 'on' state (49.15 vs. 80.69, p<0.001). Dysarthria and disequilibrium were common in patients with bilateral stimulation. A DBS-related surgery (electrode revision or internal pulse generator exchange) was necessary on average every 47.9 months to continue with the DBS therapy., Conclusions: Thalamic DBS is a safe and effective therapy in patients with essential tremor followed for up to 13 years.

Background: Patients with Parkinson's disease (PD) may develop freezing of gait (FOG) with chronic deep brain stimulation (DBS) of the subthalamic nucleus (STN) at the commonly used frequency of 130 Hz and FOG can be ameliorated by 60 Hz stimulation in some patients. It is not clear whether the development of FOG is due to the disease progression or the chronic stimulation at this 130 Hz frequency., Aims: To investigate the effect of stimulation frequency on immediate FOG in newly activated STN DBS patient with PD and determine if stimulation frequency alone could affect the FOG., Methods: Two cases of PD who developed FOG immediately upon activation of the newly placed STN DBS were studied for the effect of stimulation frequency on FOG in both `off' and `on' medication status., Results: Both patients developed severe FOG with the commonly used 130 Hz stimulation. Switching the frequency to 60 Hz immediately alleviated the FOG, without change in contacts, voltages and pulse widths. This frequency effect on FOG was present in both `off' and `on' statuses and remained effective during the 10-month follow-up period., Conclusion: These two cases demonstrate that lower frequency stimulation of 60 Hz could improve FOG, while the commonly used 130 Hz stimulation could cause FOG or make it worse. In addition, the beneficial effect of low frequency DBS was additive to dopaminergic medication effect and included other axial symptoms.