Non-motor effects of deep brain stimulation in dystonia: A systematic review

Neural correlates of anxiety in adult-onset isolated dystonia

Psychiatric disturbances are commonly associated with adult-onset isolated dystonia (AOID); however, the mechanisms underlying psychiatric abnormalities in AOID remain unknown. We aimed to investigate the structural and functional brain changes in AOID patients with anxiety, and identify imaging biomarkers for diagnosing anxiety. Structural and functional magnetic resonance was performed on 69 AOID patients and 35 healthy controls (HCs). The Hamilton Anxiety Scale (HAMA) was used to assess anxiety symptoms in AOID patients and assign patients to AOID with and without anxiety groups. Group differences in grey matter volume, amplitude of low-frequency fluctuations (ALFF), fractional ALFF, and regional homogeneity (ReHo) were evaluated. Area under the receiver operating characteristic curve (ROC AUC) was used as a metric to identify imaging biomarkers for diagnosing anxiety. AOID patients with anxiety exhibited an increased ALFF and ReHo in the left angular gyrus (ANG.L) compared with those without and HCs (voxel P<0.001 and cluster P<0.05, corrected using GRF). A significant positive correlation was observed between ALFF (r = 0.627, P<0.001) and ReHo (r = 0.515, P<0.001) in the ANG.L and HAMA scores in AOID patients. ALFF and ReHo in the ANG.L exhibited an ROC AUC of 0.904 and 0.851, respectively, in distinguishing AOID patients with anxiety from those without and an ROC AUC of 0.887 and 0.853, respectively, in distinguishing AOID patients with anxiety from HCs. These findings provide new insights into the pathophysiology of psychiatric disturbances and highlight potential candidate biomarkers for identifying anxiety in AOID patients.

Effect of deep brain stimulation on postoperative body mass index: A systematic review and meta-analysis

BACKGROUND

Deep Brain Stimulation (DBS) is FDA-approved for several movement disorders; such as Parkinson's disease, dystonia, and neuropsychiatric disorders. There are various reports of Body mass index (BMI) changes following different DBS targets in various disorders.

AIM

A comprehensive systematic review and meta-analysis were conducted to investigate the impact of DBS on patients' Body Mass Index (BMI) and provide an in-depth overview of its underlying mechanisms.

MATERIALS AND METHODS

We conducted research according to PRISMA guidelines. Our study assessed comprehensively electronic databases, including Pubmed, Scopus, Embase, web of science, and the Cochrane Library, up to May 2024. The random-effect model analysis was performed by the Comprehensive Meta-analysis software (CMA) version 3.0. As well, Cochran's Q test was used to determine the statistical heterogeneity of included studies.

RESULT

This systematic review ultimately included 49 studies, 46 of which entered the meta-analysis. The total number of patients was 1478, consisting of Parkinson's disease (PD), dystonia, and the obsessive compulsive disorder (OCD) patients. The most common DBS target was subthalamic nucleus, followed by globus pallidus internus (GPi). Our meta-analysis depicted the BMI of participants significantly mount after DBS electrode implantation (SMD = -0.542, 95%CI: -0.678 to -0.406, and P-value < 0.001). However, moderate to high heterogeneity was detected among the studies (I2 = 67.566%). Additionally, the Daily energy intake (DEI) of patients significantly decreased after DBS (SMD: 0.457, 95%CI; 0.205 to 0.709, and P-value < 0.001).

CONCLUSION

STN and GPi DBS can lead to weight gain through distinct central pathways in various movement and neuropsychiatric disorders, posing a potential risk for obesity, insulin resistance, and metabolic syndrome.

Quality of life outcomes after deep brain stimulation in acquired dystonia: a systematic review and meta-analysis

BACKGROUND

Dystonia is a condition that affects the ability to control the movement and function of the body's muscles. It can cause not only physical problems, but also mental problems, resulting in impaired health-related quality of life (HRQoL). However, the effect of deep brain stimulation on quality of life in acquired dystonia remains unclear.

METHODS

We conducted a systematic literature review from January 2000 to October 2022，determined the eligible studies, and performed a meta-analysis of HRQoL outcomes based on the Short-Form Health Survey-36 (SF-36) after DBS to evaluate the effects of DBS on physical and mental QoL.

RESULTS

A total of 14 studies met the inclusion criteria and were systematically reviewed. A comprehensive meta-analysis was performed for 9 studies that reported physical and psychological data or physical component summary (PCS), or mental component summary (MCS) for SF-36. The mean (SD) age at DBS implantation was 34.29 (10.3) years, and the follow-up period after implantation was 2.21 (2.80) years. The random effects model meta-analysis revealed that both physical and mental domains of the SF-36 improved following DBS. There was no statistically significant difference between the physical domains (effect size=1.34; p<0.0001) and the mental domains (effect size=1.38; p<0.0001).

CONCLUSION

This is the first meta-analysis that demonstrates significant benefits in HRQoL following DBS in patients with acquired dystonia. There were significant improvements in both physical QoL and mental QoL.

Neuromodulation in Dystonia - Harnessing the Network

Adult-onset isolated focal dystonia (AOIFD) is a network disorder characterised by abnormalities of sensory processing and motor control. These network abnormalities give rise to both the phenomenology of dystonia and the epiphenomena of altered plasticity and loss of intracortical inhibition. Existing modalities of deep brain stimulation effectively modulate parts of this network but are limited both in terms of targets and invasiveness. Novel approaches using a variety of non-invasive neuromodulation techniques including transcranial stimulation and peripheral stimulation present an interesting alternative approach and may, in conjunction with rehabilitative strategies, have a role in tailored therapies targeting the underlying network abnormality behind AOIFD.

Deep Brain Stimulation in childhood-onset dystonia due to brain pathology. A long-term study

BACKGROUND

Pallidal Deep Brain Stimulation (DBS) is an established treatment option for isolated, inherited or idiopathic dystonia, however data on its safety and efficacy in other forms of dystonia are more limited.

OBJECTIVES

Retrospective analysis of motor and non-motor outcomes in pediatric onset refractory dystonia due to static or progressive brain disorders in a cohort of patients with a DBS treatment duration ≥12 months.

METHODS

Multidisciplinary assessments including standardised scales/tests of motor function, pain, quality of life, cognition and language were carried out before implantation and longitudinally afterwards.

RESULTS

9 patients were included, 7 had cerebral palsy. Mean age at implantation was 209 months ± 156, mean treatment duration 84 ± 37 months. DBS was well tolerated and positively affected both motor and non-motor functions. In particular, statistically significant improvements were documented in Burke-Fahn-Marsden Scale scores (- 19.9% p 0.01031) at 12 months and in long-term quality of life (+28.6%, p 0.0292).

CONCLUSIONS

DBS may be a useful treatment option in generalized dystonia associated with brain pathology. Even when the motor benefits are limited, improvements in quality of life and non-motor functions, or the possible prevention of serious dystonia-related complications, may have a significant impact on overall clinical status.

Improvement of Non-motor Symptoms and Quality of Life After Deep Brain Stimulation for Refractory Dystonia: A 1-Year Follow-Up

Introduction: Deep brain stimulation (DBS) is a treatment option for refractory dystonia's motor symptoms, while its non-motor symptoms (NMS) have been less systematically assessed. We aimed to describe the effects of DBS on NMS in refractory generalized inherited/idiopathic dystonia prospectively.

Methods: We evaluated patients before and 1 year after DBS surgery and applied the following scales: Burke–Fahn–Marsden Rating Scale (BFMRS), NMS Scale for Parkinson's Disease (NMSS-PD), Parkinson's Disease Questionnaire-8, short-form Brief Pain Inventory (BPI), Neuropathic Pain Symptom Inventory (NPSI), and short-form McGill Pain Questionnaire (MPQ).

Results: Eleven patients (38.35 ± 11.30 years) underwent surgery, all with generalized dystonia. Motor BFMRS subscore was 64.36 ± 22.94 at baseline and 33.55 ± 17.44 1 year after DBS surgery (47.9% improvement, p = 0.003). NMSS-PD had a significant change 12 months after DBS, from 70.91 ± 59.07 to 37.18 ± 55.05 (47.5% improvement, p = 0.013). NMS changes were mainly driven by changes in the gastrointestinal (p = 0.041) and miscellaneous domains (p = 0.012). Seven patients reported chronic pain before DBS and four after it. BPI's severity and interference scores were 4.61 ± 2.84 and 4.12 ± 2.67, respectively, before surgery, and 2.79 ± 2.31 (0.00–6.25) and 1.12 ± 1.32 (0.00–3.00) after, reflecting a significant improvement (p = 0.043 and p = 0.028, respectively). NPSI score was 15.29 ± 13.94 before, while it was reduced to 2.29 ± 2.98 afterward (p = 0.028). MPQ's total score was 9.00 ± 3.32 before DBS, achieving 2.71 ± 2.93 after (p = 0.028).

Conclusions: DBS improves NMS in generalized inherited/idiopathic dystonia, including chronic pain.

The prevalence of anxiety in adult-onset isolated dystonia: A systematic review and meta-analysis

BACKGROUND AND PURPOSE

Clinically relevant anxiety and anxiety disorders are commonly associated with adult-onset isolated dystonia, contributing substantially to quality-of-life impairment in patients with this movement disorder. However, the prevalence of anxiety symptoms and disorders in adult-onset isolated dystonia remains unclear. We aimed to conduct a systematic review and meta-analysis of the prevalence of anxiety symptoms/disorders in adult-onset isolated dystonia.

METHODS

Studies reporting the prevalence of anxiety disorders determined through diagnostic interviews or from clinically relevant anxiety symptoms detected with rating scales were identified in three databases (MEDLINE, EMBASE and PsycINFO). The gray literature was also examined to detect studies not captured through the search strategy.

RESULTS

The search strategy yielded 6535 citations; 34 studies met the inclusion criteria. The overall prevalence of clinically relevant anxiety symptoms and anxiety disorders for cervical dystonia was 40% (95% confidence interval [CI] 20% to 60%); for studies examining cranial dystonia it was 25% (95% CI 21% to 30%); for studies exploring mixed populations of adult-onset isolated dystonia it was 33.3% (95% CI 22% to 43%), 26% (95% CI 12% to 40%) for laryngeal dystonia, and 32% (95% CI 21% to 43%) for upper limb dystonia. Social phobia was the most prevalent anxiety disorder across the different forms of adult-onset isolated dystonia. Between-study statistical heterogeneity was high for most prevalence estimates.

CONCLUSIONS

Clinically relevant anxiety and anxiety disorders are common across all forms of adult-onset isolated dystonia. New research avenues should explore and plan the development of pathways of care targeting these important non-motor features.

Deep Brain Stimulation for Tremor and Dystonia

Deep brain stimulation (DBS) is the most commonly used surgical treatment for drug-refractory movement disorders such as tremor and dystonia. Appropriate patient selection along with target selection is important to ensure optimal outcome without complications. This review summarizes the recent literature regarding the mechanism of action, indications, outcome, and complications of DBS in tremor and dystonia. A comparison with other modalities of surgical interventions is discussed along with a note of the recent advances in technology. Future research needs to be directed to understand the underlying etiopathogenesis of the disease and the way in which DBS modulates the intracranial abnormal networks.

A practical guide to troubleshooting pallidal deep brain stimulation issues in patients with dystonia

High frequency deep brain stimulation (DBS) of the internal portion of the globus pallidus has, in the last two decades, become a mainstream therapy for the management of medically-refractory dystonia syndromes. Such increasing uptake places an onus on movement disorder physicians to become familiar with this treatment modality, in particular optimal patient selection for the procedure and how to troubleshoot problems relating to sub-optimal efficacy and therapy-related side effects. Deep brain stimulation for dystonic conditions presents some unique challenges. For example, the frequent lack of immediate change in clinical status following stimulation alterations means that programming often relies on personal experience and local practice rather than real-time indicators of efficacy. Further, dystonia is a highly heterogeneous disorder, making the development of unifying guidelines and programming algorithms for DBS in this population difficult. Consequently, physicians may feel less confident in managing DBS for dystonia as compared to other indications e.g. Parkinson's disease. In this review, we integrate our years of personal experience of the programming of DBS systems for dystonia with a critical appraisal of the literature to produce a practical guide for troubleshooting common issues encountered in patients with dystonia treated with DBS, in the hope of improving the care for these patients.

Abnormal sensory thresholds of dystonic patients are not affected by deep brain stimulation

BACKGROUND

Unlike motor symptoms, the effects of deep brain stimulation (DBS) on non-motor symptoms associated with dystonia remain unknown.

METHODS

The objective of this study was to assess the effects of DBS on evoked experimental pain and cutaneous sensory thresholds in a crossover, double-blind on/off study and compare these results with those of healthy volunteers (HV).

RESULTS

Sixteen patients with idiopathic dystonia (39.9 ± 13 years old, n = 14 generalized) with DBS of the globus pallidus internus underwent a battery of quantitative sensory testing and assessment using a pain top-down modulation system (conditioned pain modulation, CPM). Results for the more and less dystonic body regions were compared in on and off stimulation. The patients' results were compared to age- and sex-matched HV. Descending pain modulation CPM responses in dystonic patients (on-DBS, 11.8 ± 40.7; off-DBS, 1.8 ± 22.1) was abnormally low (defective) compared to HV (-15.6 ± 23.5, respectively p = .006 and p = .042). Cold pain threshold and cold hyperalgesia were 54.8% and 95.7% higher in dystonic patients compared to HV. On-DBS CPM correlated with higher Burke-Fahn-Marsden disability score (r = 0.598; p = .014). While sensory and pain thresholds were not affected by DBS on/off condition, pain modulation was abnormal in dystonic patients and tended to be aggravated by DBS.

CONCLUSION

The analgesic effects after DBS do not seem to depend on short-duration changes in cutaneous sensory thresholds in dystonic patients and may be related to changes in the central processing of nociceptive inputs.

Weight Change After Subthalamic Nucleus Deep Brain Stimulation in Patients With Isolated Dystonia

Purpose: Deep brain stimulation of the subthalamic nucleus (STN-DBS) is an effective treatment method for advanced Parkinson's disease (PD) and isolated dystonia and provides marked improvement of major motor symptoms. In addition, non-motor effects have been reported including weight gain (WG) in patients with PD after STN-DBS. However, it is still unclear whether patients with isolated dystonia also experience WG. Methods: Data from 47 patients with isolated dystonia who underwent bilateral STN-DBS surgery between October 2012 and June 2019 were retrospectively collected. The severity of dystonia was assessed via the Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS). Changes in the body mass index (BMI) and BFMDRS score were analyzed using paired Student's t-tests. Regression analysis was performed to identify factors that affected the BMI after surgery. Results: Postoperative WG was observed in 78.7% of patients. The percentage of overweight and obese patients increased from 25.5% (before STN-DBS) to 48.9% (at the last follow-up). The mean BMI and mean percentage change in BMI increased by 1.32 ± 1.83 kg/m2 (P < 0.001) and 6.28 ± 8.34%, respectively. BMI increased more in female than in male patients. At the last follow-up, BFMDRS movement and disability scores improved by 69.76 ± 33.23% and 65.66 ± 31.41%, respectively (both P < 0.001). The final regression model analysis revealed that sex and preoperative BMI alone were independently associated with BMI change (P < 0.05). Conclusions: STN-DBS is associated with postoperative WG with patients with isolated dystonia. WG is more prominent in female patients and is associated with preoperative weight but not with the efficacy of STN-DBS on motor symptoms.

Complete resolution of postherpetic neuralgia following pallidotomy: case report

The authors report on a female patient with left-dominant Parkinson's disease with motor fluctuations and levodopa-induced dyskinesias and comorbid postherpetic neuralgia (PHN), who underwent a right-sided pallidotomy. Besides a substantial improvement in her Parkinson's symptoms, she reported an immediate and complete disappearance of PHN. This neuralgia had been long-standing, pharmacologically refractory, and severe (preoperative Brief Pain Inventory [BPI] pain severity score of 8.0, BPI pain interference score of 7.3, short-form McGill Pain Questionnaire sensory pain rating index of 7 and affective pain rating index of 10, Present Pain Intensity rank value of 4, and visual analog scale score of 81 mm; all postoperative scores were 0). She continued to be pain free at 16 months postoperatively.This peculiar finding adds substantially to the largely unrecognized evidence for the role of the pallidum in pain processing, based on previous electrophysiological, metabolic, anatomical, pharmacological, and clinical observations. Therefore, the potential of the pallidum as a neurosurgical target for neuropathic pain warrants further investigation.

Deep brain stimulation reduces pain in children with dystonia, including in dyskinetic cerebral palsy

AIM

To establish the prevalence of dystonic pain in children and their response to deep brain stimulation (DBS).

METHOD

Dystonic pain was assessed in a cohort of 140 children, 71 males and 69 females, median age 11 years 11 months (range 3y-19y 1mo), undergoing DBS in our centre over a period of 10 years. The cohort was divided into aetiological dystonia groups: 1a, inherited; 1b, heredodegenerative; 2, acquired; and 3, idiopathic. Motor responses were measured with the Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS).

RESULTS

Dystonic pain was identified in 63 (45%) patients, 38% of whom had a diagnosis of cerebral palsy (CP). Dystonic pain improved in 90% of children and in all aetiological subgroups 1 year after DBS, while the BFMDRS motor score improved in 70%. Statistically significant improvement (p<0.01) was noted for the whole cohort on the Numerical Pain Rating Scale (n=27), Paediatric Pain Profile (n=17), and Caregivers Priorities and Child Health Index of Life with Disabilities questionnaire (n=48). There was reduction of pain severity, frequency, and analgesia requirement. Findings were similar for the whole cohort and aetiological subgroups other than the inherited heredodegenerative group where the improvement did not reach statistical significance.

INTERPRETATION

Dystonic pain is frequent in children with dystonia, including those with CP, who undergo DBS; this can be an important, realizable goal of surgery irrespective of aetiology. We encourage the use of multimodal approach in pain research to reduce the risk of bias.

Long term perceptions of illness and self after Deep Brain Stimulation in pediatric dystonia: A narrative research

BACKGROUND

Deep Brain Stimulation (DBS) is increasingly used in pediatric patients affected by isolated dystonia, with excellent results. Despite well documented long-term effects on motor functioning, information on quality of life and social adaptation is almost lacking.

OBJECTIVES

The present study aims to explore the experience of illness and the relation with the device in adult patients suffering from dystonia who underwent DBS surgery in pediatric age.

METHODS

A narrative inquiry approach was used to collect patients' narratives of their experience with dystonia and DBS stimulator. A written interview was administered to 8 patients over 18 years old with generalized isolated dystonia who had undergone pallidal DBS implantation in childhood. A thematic analysis was realized to examine the narratives collected.

RESULTS

Five main themes emerged: "relationship with the disease", "experience related to DBS procedure", "relationship with one's own body", "fears", "thoughts about future". Despite a general satisfaction in relation to DBS intervention, some patients expressed difficulties, such as the acceptance of changes in one's own body, concerns and fears regarding the device and the future, also considering the critical phase of transition from childhood to adulthood.

CONCLUSIONS

These results suggest that further research is needed to understand the contribution of psychological, as much as medical, aspects to the overall outcome of the intervention. The present explorative study encourages a deeper investigations of psychological aspects of patients, in order to plan a tailored care path and to decide whether to suggest a psychological support, both before and after the intervention.

Quality of life outcomes after deep brain stimulation in dystonia: A systematic review

Dystonia is an incurable movement disorder which can cause not only physical but also mental problems, leading to impaired health-related quality of life (HRQoL). For patients with dystonia refractory to medical treatment, deep brain stimulation (DBS) is a well-established surgical treatment. The objective of this systematic review is to provide a better understanding of HRQoL outcomes after DBS for dystonia. A search of the literature was conducted using Medline (PubMed), Embase, and Cochrane Library databases in May 2019. HRQoL outcomes after DBS along with motor outcomes were reported in a total of 36 articles involving 610 patients: 21 articles on inherited or idiopathic isolated dystonia, 5 on tardive dystonia, 3 on cerebral palsy, 2 on myoclonus-dystonia, 1 on X-linked dystonia-parkinsonism, and 3 on mixed cohorts of different dystonia subtypes. DBS improved motor symptoms in various subtypes of dystonia. Most studies on patients with inherited or idiopathic isolated dystonia showed significant improvement in physical QoL, whereas gains in mental QoL were less robust and likely related to the complexity of associated neuropsychiatric problems. HRQoL outcomes beyond 5 years remain scarce. Although the studies on patients with other subtypes of dystonia also demonstrated improvement in HRQoL after DBS, the interpretation is difficult because of a limited number of articles with small cohorts. Most articles employed generic measures (e.g. Short Form Health Survey-36) and this highlights the critical need to develop and to utilize sensitive and disease-specific HRQoL measures. Finally, long-term HRQoL outcomes and predictors of HRQoL should also be clarified.

Comparison of Subthalamic Nucleus and Globus Pallidus Internus Deep Brain Stimulation Surgery on Parkinson Disease-Related Pain

OBJECTIVE

To analyze and compare the effects of subthalamic nucleus (STN) deep brain stimulation (DBS) and globus pallidus internus (GPi)-DBS on Parkinson disease (PD)-related pain.

METHODS

A retrospective study was performed of 64 patients (28 who underwent GPi-DBS and 36 who underwent STN-DBS) with PD-related pain in our hospital between January 2017 and July 2019. A numerical rating scale (NRS) was used to evaluate the degree of pain preoperatively and 4 months after operation, and the unified PD scale III (UPDRS-III) was completed simultaneously to assess motor symptoms.

RESULTS

The average NRS score of all 64 patients after surgery was 1.09 ± 1.39, which was significantly lower than that before operation (4.44 ± 1.67; P < 0.0001). The improvement rate of NRS was 75 ± 27% in the 28 GPi-DBS patients and 79 ± 27% in the 36 STN-DBS patients, with no significant difference (P = 0.577). The improvements in NRS and UPDRS-III were significantly correlated in the STN-DBS group (r = 0.3707, P = 0.026) but not significantly correlated in the GPi-DBS group (P = 0.516).

CONCLUSIONS

Both GPi-DBS and STN-DBS were effective for analyzing PD-related pain and seemed to have similar efficacy. This study provides an important first-step toward determining different DBS targets for controlling PD-related pain. Follow-up prospective research is an appropriate next step on the path to multicenter clinical trials.