Referring Parkinson's disease patients for deep brain stimulation: a RAND/UCLA appropriateness study

Tools and criteria to select patients with advanced Parkinson's disease for device-aided therapies: a narrative review

This article provides an overview of the various screening and selection tools which have been developed over the past 25 years to identify patients with Parkinson's disease (PD) possibly eligible for device-aided therapies (DATs). For the available screening tools, we describe the target therapies (subtypes of DAT), development methods, validation data, and their use in clinical practice. In addition, the historical background and potential utility of these screening tools are discussed. The challenges in developing and validating these tools are also addressed, taking into account the differences in population, the local health care organization, and resource availability.

A Paradigm Shift in the Management of Patients with Parkinson's Disease

BACKGROUND

Technological evolution leads to the constant enhancement of monitoring systems and recording symptoms of diverse disorders.

SUMMARY

For Parkinson's disease, wearable devices empowered with machine learning analysis are the main modules for objective measurements. Software and hardware improvements have led to the development of reliable systems that can detect symptoms accurately and be implicated in the follow-up and treatment decisions.

KEY MESSAGES

Among many different devices developed so far, the most promising ones are those that can record symptoms from all extremities and the trunk, in the home environment during the activities of daily living, assess gait impairment accurately, and be suitable for a long-term follow-up of the patients. Such wearable systems pave the way for a paradigm shift in the management of patients with Parkinson's disease.

Timely referral for device-aided therapy in Parkinson's disease. Development of a screening tool

BACKGROUND

Timely referral of Parkinson's disease (PD) patients to specialized centers for treatment with device-aided therapies (DAT) is suboptimal.

OBJECTIVE

To develop a screening tool for timely referral for DAT in PD and to compare the tool with the published 5-2-1 criteria.

METHODS

A cross-sectional, observational study was performed in 8 hospitals in the catchment area of a specialized movement disorder center in the Northern part of the Netherlands. The target population comprised PD patients not yet on DAT visiting the outpatient clinic of participating hospitals. The primary outcome was apparent eligibility for referral for DAT based on consensus by a panel of 5 experts in the field of DAT. Multivariable logistic regression modelling was used to develop a screening tool for eligibility for referral for DAT. Potential predictors were patient and disease characteristics as observed by attending neurologists.

RESULTS

In total, 259 consecutive PD patients were included, of whom 17 were deemed eligible for referral for DAT (point prevalence: 6.6%). Presence of response fluctuations and troublesome dyskinesias were the strongest independent predictors of being considered eligible. Both variables were included in the final model, as well as levodopa equivalent daily dose. Decision curve analysis revealed the new model outperforms the 5-2-1 criteria. A simple chart was constructed to provide guidance for referral. Discrimination of this simplified scoring system proved excellent (AUC after bootstrapping: 0.97).

CONCLUSIONS

Awaiting external validation, the developed screening tool already appears promising for timely referral and subsequent treatment with DAT in patients with PD.

Value of functional connectivity in outcome prediction for pallidal stimulation in Parkinson disease

OBJECTIVE

Functional connectivity shows the ability to predict the outcome of subthalamic nucleus deep brain stimulation (DBS) in Parkinson disease (PD). However, evidence supporting its value in predicting the outcome of globus pallidus internus (GPi) DBS remains scarce. In this study the authors investigated patient-specific functional connectivity related to GPi DBS outcome in PD and established connectivity models for outcome prediction.

METHODS

The authors reviewed the outcomes of 21 patients with PD who received bilateral GPi DBS and presurgical functional MRI at the Ruijin Hospital. The connectivity profiles within cortical areas identified as relevant to DBS outcome in the literature were calculated using the intersection of the volume of tissue activated (VTA) and the local structures as the seeds. Combined with the leave-one-out cross-validation strategy, models of the optimal connectivity profile were constructed to predict outcome.

RESULTS

Connectivity between the pallidal areas and primary motor area, supplementary motor area (SMA), and premotor cortex was identified through the literature as related to GPi DBS outcome. The similarity between the connectivity profile within the primary motor area, SMA, pre-SMA, and premotor cortex seeding from the VTA-GPi intersection from an out-of-sample patient and the constructed in-sample optimal connectivity profile predicts GPi DBS outcome (R = 0.58, p = 0.006). The predictions on average deviated by 13.1% ± 11.3% from actual improvements. On the contrary, connectivity profiles seeding from the GPi (R = -0.12, p = 0.603), the VTA (R = 0.23, p = 0.308), the VTA outside the GPi (R = 0.12, p = 0.617), or other local structures were found not to be predictive.

CONCLUSIONS

The results showed that patient-specific functional connectivity seeding from the VTA-GPi intersection could help in GPi DBS outcome prediction. Reproducibility remains to be determined across centers in larger cohorts stratified by PD motor subtype.

Clinical profiles and outcomes of deep brain stimulation in G2019S LRRK2 Parkinson disease

OBJECTIVE

The objective of this study was to evaluate clinical features and response to deep brain stimulation (DBS) in G2019S LRRK2-Parkinson disease (LRRK2-PD) and idiopathic PD (IPD).

METHODS

The authors conducted a clinic-based cohort study of PD patients recruited from the Mount Sinai Beth Israel Genetics database of PD studies. The cohort included 87 participants with LRRK2-PD (13 who underwent DBS) and 14 DBS participants with IPD enrolled between 2009 and 2017. The baseline clinical features, including motor ratings and levodopa-equivalent daily dose (LEDD), were compared among LRRK2-PD patients with and without DBS, between LRRK2-PD with DBS and IPD with DBS, and between LRRK2-PD with subthalamic nucleus (STN) and internal segment of the globus pallidus (GPi) DBS. Longitudinal motor scores (Unified Parkinson's Disease Rating Scale-part III) and medication usage were also assessed pre- and postoperatively.

RESULTS

Compared to LRRK2-PD without DBS (n = 74), the LRRK2-PD with DBS cohort (n = 13) had a significantly younger age of onset, longer disease duration, were more likely to have dyskinesia, and were less likely to experience hand tremor at disease onset. LRRK2-PD participants were also more likely to be referred for surgery because of severe dyskinesia (11/13 [85%] vs 6/14 [43%], p = 0.04) and were less likely to be referred for medically refractory tremor (0/13 [0%] vs 6/14 [43%], p = 0.02) than were IPD patients. Among LRRK2-PD patients, both STN-DBS and GPi-DBS targets were effective, although the sample size was small for both groups. There were no revisions or adverse effects reported in the GPi-DBS group, while 2 of the LRRK2-PD participants who underwent STN-DBS required revisions and a third reported depression as a stimulation-related side effect. Medication reduction favored the STN group.

CONCLUSIONS

The LRRK2-PD cohort referred for DBS had a slightly different profile, including earlier age of onset and dyskinesia. Both the STN and GPi DBS targets were effective in symptom suppression. Patients with G2019S LRRK2 PD were well-suited for DBS therapy and had favorable motor outcomes regardless of the DBS target. LRRK2-DBS patients had longer disease durations and tended to have more dyskinesia. Dyskinesia commonly served as the trigger for DBS surgical candidacy. Medication-refractory tremor was not a common indication for surgery in the LRRK2 cohort.

Neurologists' Attitudes Toward Use and Timing of Deep Brain Stimulation

OBJECTIVE

We sought to explore current perspectives and attitudes of general neurologists and movement disorder specialists toward deep brain stimulation (DBS) for Parkinson disease (PD), focusing on perspectives on its earlier use in the clinical course of the disease.

METHODS

We designed a 30-question online survey comprised of Likert-type, multiple choice, and rank-order questions, which was distributed to 932 neurologist members of the American Academy of Neurology. We analyzed clinicians' sociodemographic information, treatment patterns used for patients with PD, reasons for and against patient referral for DBS, and general attitudes toward DBS. Data were analyzed using descriptive and inferential statistics.

RESULTS

We received 164/930 completed surveys (completion rate of 18%). Overall, most respondents agreed that DBS was more useful after the appearance of motor complications and that DBS utilization offered better management of PD than medication alone. However, respondents were divided on issues like minimum duration of disease needed to consider DBS as a treatment option and timing of DBS referral relative to disease progression. Specifically, differences between movement disorder specialists and general neurologists were seen in medication management of symptoms and dyskinesia.

CONCLUSIONS

There remains a lack of consensus on several aspects of DBS, including medical management before offering DBS and the appropriate timing of its consideration for patients. Given the effect of such lack of consensus on patients' outcomes and recent evidence on positive DBS results, it is essential to update DBS professional guidelines with a focus on medical management and the timely use of DBS.

From vision to action: Canadian leadership in ethics and neurotechnology

This chapter explores the complex neuroethical aspects of neurosurgery and neuromodulation in the context of Canadian healthcare and innovation, as seen through the lens of the Pan Canadian Neurotechnology Ethics Consortium (PCNEC). Highlighted are key areas of ethical focus, each with its own unique challenges: technical advances, readiness and risk, vulnerable populations, medico-legal issues, training, and research. Through an exploration of Canadian neurotechnological practice from these various clusters, we provide a critical review of progress, describe opportunities to address areas of debate, and seek to foster ethical innovation. Underpinning this comprehensive review are the fundamental principles of solution-oriented, practical neuroethics, with beneficence and justice at the core. In our view, it is a moral imperative that neurotechnological advancements include a delineation of ethical priorities for future guidelines, oversight, and interactions.

O-Arm Navigated Frameless and Fiducial-Less Deep Brain Stimulation

Object: Deep brain stimulation (DBS) is a very useful procedure for the treatment of idiopathic Parkinson’s disease (PD), essential tremor, and dystonia. The authors evaluated the accuracy of the new method used in their center for the placing of DBS electrodes. Electrodes are placed using the intraoperative O-arm™ (Medtronic)-controlled frameless and fiducial-less system, Nexframe™ (Medtronic). Accuracy was evaluated prospectively in eleven consecutive PD patients (22 electrodes). Methods: Eleven adult patients with PD were implanted using the Nexframe system without fiducials and with the intraoperative O-arm (Medtronic) system and StealthStation™ S8 navigation (Medtronic). The implantation of DBS leads was performed using multiple-cell microelectrode recording, and intraoperative test stimulation to determine thresholds for stimulation-induced adverse effects. The accuracy was checked in three different steps: (1) using the intraoperative O-arm image and its fusion with preoperative planning, (2) using multiple-cell microelectrode recording and counting the number of microelectrodes with the signal of the subthalamic nucleus (STN) and finally, (3) total error was calculated according to a postoperative CT control image fused to preoperative planning. Results: The total error of the procedure was 1.79 mm; the radial error and the vector error were 171 mm and 163 mm. Conclusions: Implantation of DBS electrodes using an O-arm navigated frameless and fiducial-less system is a very useful and technically feasible procedure with excellent patient toleration with experienced Nexframe users. The accuracy of the method was confirmed at all three steps, and it is comparable to other published results.

Medical management after subthalamic stimulation in Parkinson's disease: a phenotype perspective

Subthalamic nucleus deep brain stimulation (STN DBS) is an established treatment that improves motor fluctuations, dyskinesia, and tremor in Parkinson's disease (PD). After the surgery, a careful electrode programming strategy and medical management are crucial, because an imbalance between them can compromise the quality of life over time. Clinical management is not straightforward and depends on several perioperative motor and non-motor symptoms. In this study, we review the literature data on acute medical management after STN DBS in PD and propose a clinical algorithm on medical management focused on the patient's phenotypic profile at the perioperative period. Overall, across the trials, the levodopa equivalent daily dose is reduced by 30 to 50% one year after surgery. In patients taking high doses of dopaminergic drugs or with high risk of impulse control disorders, an initial reduction in dopamine agonists after STN DBS is recommended to avoid the hyperdopaminergic syndrome, particularly hypomania. On the other hand, a rapid reduction of dopaminergic agonists of more than 70% during the first months can lead to dopaminergic agonist withdrawal syndrome, characterized by apathy, pain, and autonomic features. In a subset of patients with severe dyskinesia before surgery, an initial reduction in levodopa seems to be a more reasonable approach. Finally, when the patient's phenotype before the surgery is the severe parkinsonism (wearing-off) with or without tremor, reduction of the medication after surgery can be more conservative. Individualized medical management following DBS contributes to the ultimate therapy success.

An International Survey of Deep Brain Stimulation Utilization in Asia and Oceania: The DBS Think Tank East

Introduction: To evaluate the current utilization and challenges in fully implementing the use of deep brain stimulation (DBS) treatment in Asia and Oceania.

Methods: We conducted a medical literature search to identify DBS research performed by investigators with a primary affiliation in Asian and Oceania countries between March 1, 2013, and March 1, 2019, followed by an international survey-based study. Additionally, we obtained added information regarding the DBS challenges and opportunities from the technology/industry perspective within China and Japan. We also described the current situation of DBS in India.

Results: Most publications (390/494; 78.95%) in the English language originated from East Asia. In West Asia, Turkey, Israel, and Iran accounted for most DBS publications. We found no publications from the remaining 35 Asian countries. Lack of community referrals to tertiary centers was identified as the most common limitation for the widespread use of DBS in Asia (68.97%). In China, despite an increasing number of centers performing DBS surgeries, most of them accomplished less than 10 cases per year. In contrast, the number of DBS cases in Japan has been decreasing. Centers offering DBS surgeries as well as corresponding fellowship training in India are limited.

Conclusion: Appropriate referrals, access, infrastructure, and the presence of full multidisciplinary DBS teams are common limitations of DBS in Asia. Most centers in China, Japan, and India performed less than 10 cases per year and a future study is expected to address the impact on quality in centers performing such few cases.

The Study of Subthalamic Deep Brain Stimulation for Parkinson Disease-Associated Camptocormia

BACKGROUND Camptocormia is an axis symptom of Parkinson disease. It remains uncertain whether treatment with medications and surgery are effective. In this study, we assessed the efficacy of subthalamic nucleus deep brain stimulation (STN DBS) in Parkinson disease-associated camptocormia and explored some of its mechanisms. MATERIAL AND METHODS Parkinson disease-associated camptocormia was diagnosed by the following procedures. All patients underwent bilateral STN DBS. The patents' camptocormia was rated by degree and MDS Unified Parkinson's Disease Rating Scale (UPDRS) item 3.13 before and after DBS surgery. Rehabilitation and psychological interventions were used after surgery, in addition to adjustments of medication and stimulus parameters. The treatment effects on camptocormia were assessed comparing medication-off (presurgery) versus stimulation-on (post-surgery). Ethical approval for this study was provided through the Center of Human Research Ethics Committee (No. 2019-35). This study trial was registered in Chinese Clinical Trial Registry (No. ChiCTR1900022655). All the participants provided written informed consent. RESULTS After DBS surgery, all of study patients' symptoms were improved, with different levels of improvement. The minimum and maximum improvement rates were 20% and 100% respectively. The score of item 3.13 of the MDS-UPDRS III and the degree of camptocormia were found to be obviously improved (P<0.05). CONCLUSIONS STN DBS can improve Parkinson disease-associated camptocormia; STN DBS assisted with rehabilitation and psychological intervention appears to be more effective.

Diagnosis and Treatment of Parkinson Disease: A Review

IMPORTANCE

Parkinson disease is the most common form of parkinsonism, a group of neurological disorders with Parkinson disease-like movement problems such as rigidity, slowness, and tremor. More than 6 million individuals worldwide have Parkinson disease.

OBSERVATIONS

Diagnosis of Parkinson disease is based on history and examination. History can include prodromal features (eg, rapid eye movement sleep behavior disorder, hyposmia, constipation), characteristic movement difficulty (eg, tremor, stiffness, slowness), and psychological or cognitive problems (eg, cognitive decline, depression, anxiety). Examination typically demonstrates bradykinesia with tremor, rigidity, or both. Dopamine transporter single-photon emission computed tomography can improve the accuracy of diagnosis when the presence of parkinsonism is uncertain. Parkinson disease has multiple disease variants with different prognoses. Individuals with a diffuse malignant subtype (9%-16% of individuals with Parkinson disease) have prominent early motor and nonmotor symptoms, poor response to medication, and faster disease progression. Individuals with mild motor-predominant Parkinson disease (49%-53% of individuals with Parkinson disease) have mild symptoms, a good response to dopaminergic medications (eg, carbidopa-levodopa, dopamine agonists), and slower disease progression. Other individuals have an intermediate subtype. For all patients with Parkinson disease, treatment is symptomatic, focused on improvement in motor (eg, tremor, rigidity, bradykinesia) and nonmotor (eg, constipation, cognition, mood, sleep) signs and symptoms. No disease-modifying pharmacologic treatments are available. Dopamine-based therapies typically help initial motor symptoms. Nonmotor symptoms require nondopaminergic approaches (eg, selective serotonin reuptake inhibitors for psychiatric symptoms, cholinesterase inhibitors for cognition). Rehabilitative therapy and exercise complement pharmacologic treatments. Individuals experiencing complications, such as worsening symptoms and functional impairment when a medication dose wears off ("off periods"), medication-resistant tremor, and dyskinesias, benefit from advanced treatments such as therapy with levodopa-carbidopa enteral suspension or deep brain stimulation. Palliative care is part of Parkinson disease management.

CONCLUSIONS AND RELEVANCE

Parkinson disease is a heterogeneous disease with rapidly and slowly progressive forms. Treatment involves pharmacologic approaches (typically with levodopa preparations prescribed with or without other medications) and nonpharmacologic approaches (such as exercise and physical, occupational, and speech therapies). Approaches such as deep brain stimulation and treatment with levodopa-carbidopa enteral suspension can help individuals with medication-resistant tremor, worsening symptoms when the medication wears off, and dyskinesias.

Neuromodulatory procedures for gait disorders in Parkinson's disease

The neurophysiology of gait is complex and involves numerous structures in the central nervous system. Gait disorders occur frequently in Parkinson's disease (PD), and their management may become cumbersome, especially in the more advanced stages. Neuromodulatory treatments, including deep brain stimulation, cortical stimulation and spinal cord stimulation, are reviewed with respect to their effectiveness to improve gait in PD patients. Although positive effects have been reported for all of these procedures, many issues remain in view of methodological heterogeneity, variability in outcome measures and sample size. Gait in PD remains a difficult issue with a tremendous impact on quality of life, for which future research is badly needed.

Optimizing the deep brain stimulation care pathway in patients with Parkinson's disease

Management of Parkinson's disease (PD) using deep brain stimulation (DBS) requires complex care in specialized, multidisciplinary centers. A well-organized, efficient patient flow is crucial to ensure that eligible patients can quickly access DBS. Delays or inefficiencies in patient care may impact a center's ability to meet demand, creating a capacity bottleneck. Analysis of the current practices within a center may help identify areas for improvement. After external audit of the DBS workflow of the Lyon Neurological Hospital and comparison with other European centers, manageable steps were suggested to restructure the care pathway. Propositions of the audit comprised, for example: (1) directly admitting referred patients to hospital, without a prior neurological outpatient visit and (2) including the preoperative anesthesia consultation in the hospital stay 1 month before surgery, not separately. This reorganization (between 2013 and 2016) was performed without increases in hospital medical resources or costs. The time from patients' first referral to surgery was reduced (from 22 to 16 months; p = 0.033), as was the number of pre- and postoperative patient visits (11-5; p = 0.025) and the total cumulative length of in-hospital stay (20.5-17.5 nights; p = 0.02). Ultimately, the total number of PD consultations increased (346-498 per year), as did the number of DBS implants per year (32-45 patients). In this single center experience, restructuring the DBS care pathway allowed a higher number of PD patients to benefit from DBS therapy, with a shorter waiting time and without decreasing the quality of care.

Current Topics in Deep Brain Stimulation for Parkinson Disease

There is a long history of surgical treatment for Parkinson disease (PD). After pioneering trials and errors, the current primary surgical treatment for PD is deep brain stimulation (DBS). DBS is a promising treatment option for patients with medically refractory PD. However, there are still many problems and controversies associated with DBS. In this review, we discuss current issues in DBS for PD, including patient selection, clinical outcomes, complications, target selection, long-term outcomes, management of axial symptoms, timing of surgery, surgical procedures, cost-effectiveness, and new technology.