Editing Deep brain stimulation (section)

====Gait====
The effect on gait is inconsistent, with multiple studies showing worsening of gait, balance and speech as potential complications of DBS,<ref>{{cite journal |last1=Tanner |first1=CM |last2=Ostrem |first2=JL |title=Parkinson's Disease. |journal=The New England Journal of Medicine |date=1 August 2024 |volume=391 |issue=5 |pages=442–452 |doi=10.1056/NEJMra2401857 |pmid=39083773}}</ref> with DBS to the STN carrying a higher risk of gait dysfunction.<ref>{{cite journal |last1=Tsuboi |first1=T |last2=Au |first2=KLK |last3=Deeb |first3=W |last4=Almeida |first4=L |last5=Foote |first5=KD |last6=Okun |first6=MS |last7=Ramirez-Zamora |first7=A |title=Motor outcomes and adverse effects of deep brain stimulation for dystonic tremor: A systematic review. |journal=Parkinsonism & Related Disorders |date=July 2020 |volume=76 |pages=32–41 |doi=10.1016/j.parkreldis.2020.06.008 |pmid=32559631}}</ref> A study delineating adverse effects by time found that though DBS mitigated gait symptoms after surgery, postoperative postural instability and gait disorders worsened in the long term.<ref name = "Persistent 2018"/>

When axial symptoms are responsive to dopaminergic medications, they are likely to improve with DBS. Several studies reported gait improvement with either STN or GPi DBS, including reduction in freezing of gait, though GPi is generally associated with preserved gait function compared with STN,<ref name="JAMA Neurol 2018"/> and generally more favorable for those with axial symptoms, gait issues, depression, and word fluency problems.<ref name="Vanderbilt 2017"/>

[[Electromyography]] studies of the lower limbs in the study of gait have shown that dopaminergic medication increases distal lower limb muscle activity while STN DBS increases both proximal and distal lower limb muscle activity.<ref>{{cite journal |last1=Islam |first1=A |title=Effect of Parkinson's disease and two therapeutic interventions on muscle activity during walking: a systematic review. |journal=npj Parkinson's Disease |date=2020 |volume=6 |page=22 |doi=10.1038/s41531-020-00119-w |pmid=32964107|pmc=7481232 }}</ref>

In the context of chronic levodopa therapy, the most relevant effect of STN neurostimulation is improvement of motor function during the off state, the period during which symptoms are non responsive to dopamine.<ref name="Lancet 2013">{{cite journal |last1=Deuschl |first1=G |last2=Agid |first2=Y |title=Subthalamic neurostimulation for Parkinson's disease with early fluctuations: balancing the risks and benefits. |journal=The Lancet. Neurology |date=October 2013 |volume=12 |issue=10 |pages=1025–34 |doi=10.1016/S1474-4422(13)70151-0 |pmid=24050735}}</ref>