Subthalamic Nucleus Stimulation in Pediatric Isolated Dystonia: A 10-Year Follow-up

How Long Does Deep Brain Stimulation Give Patients Benefit?

INTRODUCTION

One of the most common questions patients ask when they are contemplating deep brain stimulation (DBS) is how long it will last. To guide physicians in answering this query, we performed a scoping review to assess the current state of the literature and to identify the gaps that need to be addressed.

MATERIALS AND METHODS

The authors performed a MEDLINE search inclusive of articles from January 1987 (advent of DBS literature) to June 2023 including human and modeling studies written in English. For longevity of therapy data, only studies with a mean follow-up of ≥three years were included. Using the Rayyan platform, two reviewers (JP and RM) performed a title screen. Of the 734 articles, 205 were selected by title screen and 109 from abstract review. Ultimately, a total of 122 articles were reviewed. The research questions we explored were 1) how long can the different components of the DBS system maintain functionality? and 2) how long can DBS remain efficacious in treating Parkinson's disease (PD), essential tremor (ET), dystonia, and other disorders?

RESULTS

We showed that patients with PD, ET, and dystonia maintain a considerable long-term benefit in motor scores seven to ten years after implant, although the percentage improvement decreases over time. Stimulation off scores in PD and ET show worsening, consistent with disease progression. Battery life varies by the disease treated and the programming settings used. There remains a paucity of literature after ten years, and the impact of new device technology has not been classified to date.

CONCLUSION

We reviewed existing data on DBS longevity. Overall, outcomes data after ten years of therapy are substantially limited in the current literature. We recommend that physicians who have data for patients with DBS exceeding this duration publish their results.

The role of genetics in the treatment of dystonia with deep brain stimulation: Systematic review and Meta-analysis

BACKGROUND

Dystonia is a movement disorder characterized by sustained or intermittent muscle contractions that lead to involuntary postures or repetitive movements. Genetic mutations are being increasingly recognized as a cause of dystonia. Deep brain stimulation (DBS) is one of the limited treatment options available. However, there are varying reports on its efficacy in genetic dystonias. This systematic review of the characteristics of genetic dystonias treated with DBS and their outcomes aims to aid in the evaluation of eligibility for such treatment.

METHODS

We performed a PUBMED search of all papers related to genetic dystonias and DBS up until April 2022. In addition to performing a systematic review, we also performed a meta-analysis to assess the role of the mutation on DBS response. We included cases that had a confirmed genetic mutation and DBS along with pre-and post-operative BFMDRS.

RESULTS

Ninety-one reports met our inclusion criteria and from them, 235 cases were analyzed. Based on our analysis DYT-TOR1A dystonia had the best evidence for DBS response and Rapid-Onset Dystonia Parkinsonism was among the least responsive to DBS.

CONCLUSION

While our report supports the role of genetics in DBS selection and response, it is limited by the rarity of the individual genetic conditions, the reliance on case reports and case series, and the limited ability to obtain genetic testing on a large scale in real-time as opposed to retrospectively as in many cases.

Adolescent OCD Patient and Caregiver Perspectives on Identity, Authenticity, and Normalcy in Potential Deep Brain Stimulation Treatment

The ongoing debate within neuroethics concerning the degree to which neuromodulation such as deep brain stimulation (DBS) changes the personality, identity, and agency (PIA) of patients has paid relatively little attention to the perspectives of prospective patients. Even less attention has been given to pediatric populations. To understand patients' views about identity changes due to DBS in obsessive-compulsive disorder (OCD), the authors conducted and analyzed semistructured interviews with adolescent patients with OCD and their parents/caregivers. Patients were asked about projected impacts to PIA generally due to DBS. All patient respondents and half of caregivers reported that DBS would impact patient self-identity in significant ways. For example, many patients expressed how DBS could positively impact identity by allowing them to explore their identities free from OCD. Others voiced concerns that DBS-related resolution of OCD might negatively impact patient agency and authenticity. Half of patients expressed that DBS may positively facilitate social access through relieving symptoms, while half indicated that DBS could increase social stigma. These views give insights into how to approach decision-making and informed consent if DBS for OCD becomes available for adolescents. They also offer insights into adolescent experiences of disability identity and "normalcy" in the context of OCD.

Long-Term Outcome of Subthalamic Deep Brain Stimulation for Generalized Isolated Dystonia

OBJECTIVES

Few studies have focused on subthalamic nucleus deep brain stimulation for refractory isolated dystonia, and the long-term outcomes are unclear. In this study, we evaluated the efficacy of subthalamic stimulation for generalized isolated dystonia for more than five years and explored the factors predicting clinical outcomes.

MATERIALS AND METHODS

A total of 16 patients with generalized isolated dystonia underwent a two-phase procedure for stimulation system implantation. After implanting the leads, we performed a test stimulation and observed the stimulation response. The severity of dystonia was assessed using a blinded rating of the Burke-Fahn-Marsden Dystonia Rating Scale based on videos recorded at scheduled times.

RESULTS

The mean follow-up time was 7.4 ± 2.2 years (5-12.5 years). The severity of dystonia improved significantly one year after surgery. The movement score decreased from 49.3 (40.9) points at baseline to 26.5 (43.5) points (-44.6%) at six months, 12.0 (22.5) points (-66.8%) at one year, 11.25 (17.6) points (-72.7%) at three years, and 12.5 (21.0) points (-72.6%) at the last follow-up. The improvement in motor symptoms resulted in a corresponding improvement in activities of daily living. Greater long-term outcomes were correlated with early stimulation responses, lower baseline movement scores, and female sex. When analyzed comprehensively, only the baseline movement score had meaningful predictive value for the outcome.

CONCLUSIONS

Our results indicate that subthalamic stimulation is effective and durable in treating generalized isolated dystonia. The subthalamic nucleus may be an alternative target for the treatment of refractory dystonia. Patients with less severe motor symptoms may benefit more from this treatment.

Deep brain stimulation of fornix for memory improvement in Alzheimer's disease: A critical review

Memory reflects the brain function in encoding, storage and retrieval of the data or information, which is a fundamental ability for any live organism. The development of approaches to improve memory attracts much attention due to the underlying mechanistic insight and therapeutic potential to treat neurodegenerative diseases with memory loss, such as Alzheimer's disease (AD). Deep brain stimulation (DBS), a reversible, adjustable, and non-ablative therapy, has been shown to be safe and effective in many clinical trials for neurodegenerative and neuropsychiatric disorders. Among all potential regions with access to invasive electrodes, fornix is considered as it is the major afferent and efferent connection of the hippocampus known to be closely associated with learning and memory. Indeed, clinical trials have demonstrated that fornix DBS globally improved cognitive function in a subset of patients with AD, indicating fornix can serve as a potential target for neurosurgical intervention in treating memory impairment in AD. The present review aims to provide a better understanding of recent progresses in the application of fornix DBS for ameliorating memory impairments in AD patients.

Long-Term Outcomes of Deep Brain Stimulation for Pediatric Dystonia

BACKGROUND

Deep brain stimulation (DBS) has been utilized for over two decades to treat medication-refractory dystonia in children. Short-term benefit has been demonstrated for inherited, isolated, and idiopathic cases, with less efficacy in heredodegenerative and acquired dystonia. The ongoing publication of long-term outcomes warrants a critical assessment of available information as pediatric patients are expected to live most of their lives with these implants.

SUMMARY

We performed a review of the literature for data describing motor and neuropsychiatric outcomes, in addition to complications, 5 or more years after DBS placement in patients undergoing DBS surgery for dystonia at an age younger than 21. We identified 20 articles including individual data on long-term motor outcomes after DBS for a total of 78 patients. In addition, we found five articles reporting long-term outcomes after DBS in 9 patients with status dystonicus. Most patients were implanted within the globus pallidus internus, with only a few cases targeting the subthalamic nucleus and ventrolateral posterior nucleus of the thalamus. The average follow-up was 8.5 years, with a range of up to 22 years. Long-term outcomes showed a sustained motor benefit, with median Burke-Fahn-Marsden dystonia rating score improvement ranging from 2.5% to 93.2% in different dystonia subtypes. Patients with inherited, isolated, and idiopathic dystonias had greater improvement than those with heredodegenerative and acquired dystonias. Sustained improvements in quality of life were also reported, without the development of significant cognitive or psychiatric comorbidities. Late adverse events tended to be hardware-related, with minimal stimulation-induced effects.

KEY MESSAGES

While data regarding long-term outcomes is somewhat limited, particularly with regards to neuropsychiatric outcomes and adverse events, improvement in motor outcomes appears to be preserved more than 5 years after DBS placement.

Deep Brain Stimulation for Pediatric Dystonia

Dystonia is one of the most common pediatric movement disorders and can have a profound impact on the lives of children and their caregivers. Response to pharmacologic treatment is often unsatisfactory. Deep brain stimulation (DBS) has emerged as a promising treatment option for children with medically refractory dystonia. In this review we highlight the relevant literature related to DBS for pediatric dystonia, with emphasis on the background, indications, prognostic factors, challenges, and future directions of pediatric DBS.

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.

Subthalamic Nucleus Deep Brain Stimulation in Post-Infarct Dystonia

Dystonia secondary to cerebral infarcts presents months to years after the initial insult, is usually unilateral and causes significant morbidity. Deep brain stimulation (DBS) of the globus pallidus internus (GPi) is established as the most frequent target in the management of the dystonic symptoms. We report our experience with subthalamic nucleus (STN) DBS in 3 patients with post-infarct dystonia, in whom GPi DBS was not confidently possible due to the presence of striatal infarcts. Two patients had unilateral STN DBS implantation, whereas the third patient had bilateral STN DBS implantation for bilateral dystonic symptoms. Prospectively collected preoperative and postoperative functional assessment data including imaging, medication and neuropsychology evaluations were analyzed with regard to symptom improvement. Median follow-up period was 38.3 months (range 26–43 months). All patients had clinically valuable improvements in dystonic symptoms and pain control despite variable improvements in the Burke-Fahn-Marsden dystonia rating scores. In our series, we have demonstrated that STN DBS could be an alternative in the management of post-infarct dystonia in patients with abnormal striatal anatomy which precludes GPi DBS. A multidisciplinary team-based approach is essential for patient selection and management.