Effect of deep brain stimulation on freezing of gait in patients with Parkinson's disease: a systematic review

Background and objectives Freezing of gait (FOG) is a disabling gait disorder in patients with Parkinson's disease (PD), characterized by recurrent episodes of halting steps. Dopaminergic drugs are common treatments for PD and FOG; however, these drugs may worsen FOG. Deep brain stimulation (DBS) is another option used to treat selected patients. The device needs to be programmed at a specific frequency, amplitude, and pulse width to achieve optimum effects for each patient. This systematic review aimed to evaluate the efficacy of DBS for FOG and its correlation with programmed parameters and the location of the electrodes in the brain. Materials and methods Data for this systematic review were gathered from five online databases: Medline (via PubMed), Scopus, Embase, Web of Science, and Cochrane Library (including both Cochrane Reviews and Cochrane Trials) with a broad search strategy. We included those articles that reported clinical trials and a specific measurement for FOG. Results This review included 13 studies of DBS that targeted the subthalamic nucleus (STN), substantia nigra (SNr), or pedunculopontine nucleus (PPN). Our analysis showed that low-frequency stimulation (LFS) was superior to high-frequency stimulation (HFS) for improving FOG. In the long term, the efficacy of both LFS and HFS decreased. The effect of amplitude was variable, and this parameter needed to be adjusted for each patient. Bilateral stimulation was better than unilateral stimulation. Conclusion DBS is a promising choice for the treatment of severe FOG in patients with PD. Bilateral, low-frequency stimulation combined with medical therapy is associated with better responses, especially in the first 2 years of treatment. However, individualizing the DBS parameters should be considered to optimize treatment response.