Deep brain stimulation significantly decreases disability from low back pain in patients with advanced Parkinson's disease

Idiopathic Parkinson's disease and chronic pain in the era of deep brain stimulation: a systematic review and meta-analysis

OBJECTIVE

Pain is the most common nonmotor symptom of Parkinson's disease (PD) and is often undertreated. Deep brain stimulation (DBS) effectively mitigates the motor symptoms of this multisystem neurodegenerative disease; however, its therapeutic effect on nonmotor symptoms, especially pain, remains inconclusive. While there is a critical need to help this large PD patient population, guidelines for managing this significant disease burden are absent. Herein, the authors systematically reviewed the literature and conducted a meta-analysis to study the influence of traditional (subthalamic nucleus [STN] and globus pallidus internus [GPi]) DBS on chronic pain in patients with PD.

METHODS

The authors performed a systematic review of the literature and a meta-analysis following PRISMA guidelines. Risk of bias was assessed using the levels of evidence established by the Oxford Centre for Evidence-Based Medicine. Inclusion criteria were articles written in English, published in a peer-reviewed scholarly journal, and about studies conducting an intervention for PD-related pain in no fewer than 5 subjects.

RESULTS

Twenty-six studies were identified and included in this meta-analysis. Significant interstudy heterogeneity was detected (Cochran's Q test p < 0.05), supporting the use of the random-effects model. The random-effects model estimated the effect size of DBS for the treatment of idiopathic pain as 1.31 (95% CI 0.84-1.79). The DBS-on intervention improved pain scores by 40% as compared to the control state (preoperative baseline or DBS off).

CONCLUSIONS

The results indicated that traditional STN and GPi DBS can have a favorable impact on pain control and improve pain scores by 40% from baseline in PD patients experiencing chronic pain. Further trials are needed to identify the subtype of PD patients whose pain benefits from DBS and to identify the mechanisms by which DBS improves pain in PD patients.

Spinal Surgery after Bilateral Subthalamic Stimulation for Patients with Parkinson's Disease: A Retrospective Outcome Analysis of Pain and Functional Control

Parkinson’s disease (PD) patients often suffer from spinal diseases requiring surgeries, although the risk of complications is high. There are few reports on outcomes after spinal surgery for PD patients with deep brain stimulation (DBS). The objective of this study was to explore the data on spinal surgery for PD patients with precedent DBS. We evaluated 24 consecutive PD patients with 28 spinal surgeries from 2007 to 2017 who received at least a 2-year follow-up. The characteristics and outcomes of PD patients after spinal surgery were compared to those of 156 non-PD patients with degenerative spinal diseases treated in 2013–2017. Then, the characteristics, outcomes, and spinal alignment of PD patients receiving DBS were analyzed in degenerative spinal/lumbar diseases. The mean age at the time of spinal surgery was 68 years. The Hoehn and Yahr score regarding PD was stage 1 for 8 patients, stage 2 for 2 patients, stage 3 for 8 patients, stage 4 for 10 patients, and stage 5 for 0 patient. The median preoperative L-DOPA equivalent daily dose was 410 mg. Thirteen patients (46%) received precedent subthalamic nucleus (STN) DBS. Lumbar lesions with pain were common, and operation and anesthesia times were long in PD patients. Pain and functional improvement of PD patients persisted for 2 years after surgery with a higher complication rate than for non-PD patients. PD patients with STN DBS maintained better lumbar lordosis for 2 years after spinal surgery. STN DBS significantly maintained spinal alignment with subsequent pain and functional amelioration 2 years after surgery. The outcomes of spinal surgery for PD patients might be favorably affected by thorough treatment for PD including DBS.

Intrathecal catheter for severe low back pain during deep brain stimulation placement: illustrative case

BACKGROUND

Deep brain stimulation (DBS) is a U.S. Food and Drug Administration–approved therapy for medically refractory Parkinson’s disease, essential tremor, and other neurological conditions. The procedure requires prolonged immobility and can result in significant patient discomfort, potentially limiting patient selection. In addition, surgical requirements necessitate avoidance of medications that may alter or suppress the patient’s arousal or baseline tremor during macrostimulation testing.

OBSERVATIONS

In this study, the authors describe the use of continuous spinal anesthesia with local anesthetic to manage a patient with severe back pain who was intolerant of semisupine position during stereotactic computed tomography and stage 1 of DBS placement.

LESSONS

Continuous spinal anesthesia is an effective strategy to manage patients with severe back pain undergoing DBS surgery for upper extremity motor symptoms.

Pain in Parkinson's disease and the role of the subthalamic nucleus

Pain is a frequent and poorly treated symptom of Parkinson's disease, mainly due to scarce knowledge of its basic mechanisms. In Parkinson's disease, deep brain stimulation of the subthalamic nucleus is a successful treatment of motor symptoms, but also might be effective in treating pain. However, it has been unclear which type of pain may benefit and how neurostimulation of the subthalamic nucleus might interfere with pain processing in Parkinson's disease. We hypothesized that the subthalamic nucleus may be an effective access point for modulation of neural systems subserving pain perception and processing in Parkinson's disease. To explore this, we discuss data from human neurophysiological and psychophysical investigations. We review studies demonstrating the clinical efficacy of deep brain stimulation of the subthalamic nucleus for pain relief in Parkinson's disease. Finally, we present some of the key insights from investigations in animal models, healthy humans and Parkinson's disease patients into the aberrant neurobiology of pain processing and consider their implications for the pain-relieving effects of subthalamic nucleus neuromodulation. The evidence from clinical and experimental studies supports the hypothesis that altered central processing is critical for pain generation in Parkinson's disease and that the subthalamic nucleus is a key structure in pain perception and modulation. Future preclinical and clinical research should consider the subthalamic nucleus as an entry point to modulate different types of pain, not only in Parkinson's disease but also in other neurological conditions associated with abnormal pain processing.

An overview of pain in Parkinson's disease

Pain is a common non-motor symptom of Parkinson's disease (PD) and the prevalence of pain among PD patients varies because of the disease stage, co-morbidities, and evaluating tools. Risk factors for pain in PD include an early age of onset, long disease duration, motor complications, concomitant depressive symptoms, female gender, and associated medical conditions. In patients with PD, pain can be classified as musculoskeletal pain, chronic body pain (central or visceral), fluctuation-related pain, nocturnal pain, orofacial pain, pain with discolouration/oedema/swelling, and radicular/neuropathic pain; musculoskeletal pain as the most common type. Potential underlying mechanisms include a disruption of peripheral nociception and alterations in central pain threshold/processing. Genetic polymorphisms in genes that confer pain susceptibility might also play a role in the occurrence of pain in PD. In advanced stage of patients with PD, polyneuropathy could occur in patients using high dosage of levodopa. Pain often correlates to other non-motor symptoms of PD, including depression, sleep, and autonomic symptoms. Dopaminergic drugs, non-dopaminergic medications, botulinum toxin, deep brain stimulation, and physiotherapy have shown some benefits for certain types of PD-related pain. An increased awareness of pain as a common non-motor symptom of PD provides further insights into sensory system dysregulation in this disease. In this review, we aim to summarizes the clinical features of pain in patients with PD and emphasize the latest evidence of pain related to levodopa treatment.

Chronic pain and pain processing in Parkinson's disease

Pain is experienced by the vast majority of patients living with Parkinson's disease. It is most often of nociceptive origin, but may also be ascribed to neuropathic (radicular or central) or miscellaneous sources. The recently validated King's Parkinson's Disease Pain Scale is based on 7 domains including musculoskeletal pain, chronic body pain (central or visceral), fluctuation-related pain, nocturnal pain, oro-facial pain, pain with discolouration/oedema/swelling, and radicular pain. The basal ganglia integrate incoming nociceptive information and contribute to coordinated motor responses in pain avoidance and nocifensive behaviors. In Parkinson's disease, nigral and extra-nigral pathology, involving cortical areas, brainstem nuclei, and spinal cord, may contribute to abnormal central nociceptive processing in patients experiencing pain or not. The dopamine deficit lowers multimodal pain thresholds that are amenable to correction following levodopa dosing. Functional brain imaging with positron emission tomography following administration of H₂¹⁵O revealed abnormalities in the sensory discriminative processing of pain (insula/SII), as well as in the affective motivational processing of pain (anterior cingulate cortex, prefrontal cortex). Pain management is dependent on efforts invested in diagnostic accuracy to distinguish nociceptive from neuropathic pain. Treatment requires an integrated approach including strategies to lessen levodopa-related response fluctuations, in addition to other pharmacological and non-pharmacological options such as deep brain stimulation and rehabilitation.

King's Parkinson's Disease Pain Scale for Assessment of Pain Relief Following Deep Brain Stimulation for Parkinson's Disease

OBJECTIVE

Pain is a prevalent and debilitating nonmotor symptom of Parkinson's disease (PD) that is often inadequately managed. Deep brain stimulation (DBS) has been shown to relieve pain in PD but an effective method of identifying which types of PD pain respond to DBS has not been established. We examine the effects of DBS on different types of PD pain using the King's Parkinson's disease pain scale (KPDPS), the only validated scale of PD pain.

METHODS

We prospectively followed 18 PD patients undergoing subthalamic nucleus (STN) or Globus pallidus interna (GPi) DBS. Subjects completed the KPDPS, low back disability index (LBDI), and McGill pain questionnaire (MPQ), preoperatively and at six months postoperatively. Subjects underwent the unified Parkinson's disease rating scale-III (UPDRS-III) with preoperative scores ON medication and postoperative scores ON medication/DBS stimulation.

RESULTS

Of the 18 patients, a total of 12 subjects had STN DBS and 6 had GPi DBS. As a group, subjects showed improvement in total KPDPS score at six-month postoperative follow-up (p = 0.004). Fluctuation and nocturnal pain were most significantly improved (p = 0.006, 0.01, respectively). Significant improvements were found in fluctuation-related pain domain following GPi DBS.

CONCLUSIONS

In this pilot study, we are the first group to employ KPDPS to monitor pain relief following DBS in PD patients. We demonstrate that fluctuation-related pain and nocturnal pain significantly improve with DBS. Use of the KPDPS in the future will allow better understanding of how STN and GPi DBS treat PD pain over time.

Subthalamic deep brain stimulation alters neuronal firing in canonical pain nuclei in a 6-hydroxydopamine lesioned rat model of Parkinson's disease

INTRODUCTION

Chronic pain is one of the most common non-motor symptoms of Parkinson's disease (PD) affecting up to 85% of patients. Previous studies have established that reduced mechanical and thermal thresholds occur in both idiopathic PD patients and animal models of PD, suggesting that changes may occur in sensory processing circuits. Improvements in sensory thresholds are achieved using subthalamic nucleus (STN) deep brain stimulation (DBS), however the mechanism by which this occurs remains unresolved.

MATERIALS AND METHODS

We examined unilateral medial forebrain bundle 6-hydroxydopamine (6OHDA) rat model of PD to determine whether STN DBS alters neuronal firing rates in brain areas involved in ascending and descending pain processing. Specifically, single unit in vivo recordings were conducted in the anterior cingulate cortex (ACC), the periaqueductal grey (PAG), and the ventral posteriolateral nucleus of the thalamus (VPL), before, during and after stimulation was applied to the STN at 50 or 150Hz.

RESULTS

Sham and 6OHDA lesioned animals have similar neuronal firing activity in the VPL, ACC and PAG before stimulation was applied (p>0.05). In 6OHDA lesioned rats, both low frequency stimulation (LFS) (p<0.01) and high frequency stimulation (HFS) (p<0.05) attenuated firing frequency in the ACC. In shams, only LFS decreased firing frequency. A subset of neurons in the PAG was significantly attenuated in both sham and 6OHDA lesioned animals during HFS and LFS (p<0.05), while another subset of PAG neuronal activity significantly increased in 6OHDA lesioned rats during HFS (p<0.05). Finally, low or high frequency STN DBS did not alter neuronal firing frequencies in the VPL.

CONCLUSIONS

Our results suggest that STN DBS alters neuronal firing in descending pain circuits. We hypothesize that STN DBS attenuates excitatory projections from the ACC to the PAG in 6OHDA lesioned rats. Following this, neurons in the PAG respond by either increasing (during HFS only) or decreasing (during both LFS and HFS), which may modulate descending facilitation or inhibition at the level of the spinal cord. Future work should address specific neuronal changes in the ACC and PAG that occur in a freely moving parkinsonian animal during a pain stimulus treated with STN DBS.

Effect of low-frequency deep brain stimulation on sensory thresholds in Parkinson's disease

OBJECTIVE Chronic pain is a major distressing symptom of Parkinson's disease (PD) that is often undertreated. Subthalamic nucleus (STN) deep brain stimulation (DBS) delivers high-frequency stimulation (HFS) to patients with PD and has been effective in pain relief in a subset of these patients. However, up to 74% of patients develop new pain concerns while receiving STN DBS. Here the authors explore whether altering the frequency of STN DBS changes pain perception as measured through quantitative sensory testing (QST). METHODS Using QST, the authors measured thermal and mechanical detection and pain thresholds in 19 patients undergoing DBS via HFS, low-frequency stimulation (LFS), and off conditions in a randomized order. Testing was performed in the region of the body with the most pain and in the lower back in patients without chronic pain. RESULTS In the patients with chronic pain, LFS significantly reduced heat detection thresholds as compared with thresholds following HFS (p = 0.029) and in the off state (p = 0.010). Moreover, LFS resulted in increased detection thresholds for mechanical pressure (p = 0.020) and vibration (p = 0.040) compared with these thresholds following HFS. Neither LFS nor HFS led to changes in other mechanical thresholds. In patients without chronic pain, LFS significantly increased mechanical pain thresholds in response to the 40-g pinprick compared with thresholds following HFS (p = 0.032). CONCLUSIONS Recent literature has suggested that STN LFS can be useful in treating nonmotor symptoms of PD. Here the authors demonstrated that LFS modulates thermal and mechanical detection to a greater extent than HFS. Low-frequency stimulation is an innovative means of modulating chronic pain in PD patients receiving STN DBS. The authors suggest that STN LFS may be a future option to consider when treating Parkinson's patients in whom pain remains the predominant complaint.