Deep brain stimulation for movement disorders: update on recent discoveries and outlook on future developments

Abstract

Modern deep brain stimulation (DBS) has become a routine therapy for patients with movement disorders such as Parkinson's disease, generalized or segmental dystonia and for multiple forms of tremor. Growing numbers of publications also report beneficial effects in other movement disorders such as Tourette's syndrome, various forms of chorea and DBS is even being studied for Parkinson's-related dementia. While exerting remarkable effects on many motor symptoms, DBS does not restore normal neurophysiology and therefore may also have undesirable side effects including speech and gait deterioration. Furthermore, its efficacy might be compromised in the long term, due to progression of the underlying disease. Various programming strategies have been studied to try and address these issues, e.g., the use of low-frequency rather than high-frequency stimulation or the targeting of alternative brain structures such as the pedunculopontine nucleus. In addition, further technical developments will soon provide clinicians with an expanded choice of hardware such as segmented electrodes allowing for a steering of the current to optimize beneficial effects and reduce side effects as well as the possibility of adaptive stimulation systems based on closed-loop concepts with or without accompanying advances in programming and imaging software. In the present article, we will provide an update on the most recent achievements and discoveries relevant to the application of DBS in the treatment of movement disorder patients and give an outlook on future clinical and technical developments.

Effect of levodopa-carbidopa intestinal gel on resting tremors in patients with advanced Parkinson’s disease

“…More importantly, resting tremors are not consistently controlled with available oral therapies and are one of the main indications for invasive therapeutic procedures such as deep brain stimulation. 2,6,7 …”

DBS in Dystonia and Other Hyperkinetic Movement Disorders

“…In addition, further technical developments of hardware/electrodes will allow a better steering of the stimulation to optimize beneficial effects and reduce side effects, by directional electrodes [72] and close-loop intermittent stimulations. [73,74]. In order to reduce the risk related to open surgery, new lesional approaches (gamma knife, focused ultrasound) are starting to emerge [46][47][48][49].…”

<b>Pathophysiology and clinical management of pain in Parkinson's disease: Differences in efficacy of dopamine agonists and deep brain stimulation</b>

“…Thus, interventions targeting the BG with the aim of reversing its abnormal neuronal activities have been postulated to have a modulatory effect on pain symptoms in PD patients. Although different BG structures can be selected for stimula tion, the efficacy of DBS of the subthalamic nucleus (STN-DBS) for PD-related pain is the most well understood 37,55) . There is evidence to show that STN-DBS significantly reduces overall pain but its efficacy varies across the different subtypes of pain symptom.…”