Recommendations for the Management of Initial and Refractory Pediatric Status Dystonicus

Status dystonicus is the most severe form of dystonia with life-threatening complications if not treated promptly. We present consensus recommendations for the initial management of acutely worsening dystonia (including pre-status dystonicus and status dystonicus), as well as refractory status dystonicus in children. This guideline provides a stepwise approach to assessment, triage, interdisciplinary treatment, and monitoring of status dystonicus. The clinical pathways aim to: (1) facilitate timely recognition/triage of worsening dystonia, (2) standardize supportive and dystonia-directed therapies, (3) provide structure for interdisciplinary cooperation, (4) integrate advances in genomics and neuromodulation, (5) enable multicenter quality improvement and research, and (6) improve outcomes. © 2024 International Parkinson and Movement Disorder Society.

Neural signatures of indirect pathway activity during subthalamic stimulation in Parkinson's disease

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) produces an electrophysiological signature called evoked resonant neural activity (ERNA); a high-frequency oscillation that has been linked to treatment efficacy. However, the single-neuron and synaptic bases of ERNA are unsubstantiated. This study proposes that ERNA is a subcortical neuronal circuit signature of DBS-mediated engagement of the basal ganglia indirect pathway network. In people with Parkinson's disease, we: (i) showed that each peak of the ERNA waveform is associated with temporally-locked neuronal inhibition in the STN; (ii) characterized the temporal dynamics of ERNA; (iii) identified a putative mesocircuit architecture, embedded with empirically-derived synaptic dynamics, that is necessary for the emergence of ERNA in silico; (iv) localized ERNA to the dorsal STN in electrophysiological and normative anatomical space; (v) used patient-wise hotspot locations to assess spatial relevance of ERNA with respect to DBS outcome; and (vi) characterized the local fiber activation profile associated with the derived group-level ERNA hotspot.

A wearable system for visual cueing gait rehabilitation in Parkinson's disease: a randomized non-inferiority trial

BACKGROUND

Gait disturbances represent one of the most disabling features of Parkinson's disease (PD).

AIM

The aim of this study was to evaluate the non-inferiority of a new wearable visual cueing system (Q-Walk) for gait rehabilitation in PD subjects, compared to traditional visual cues (stripes on the floor).

DESIGN

Open-label, monocentric, randomized controlled non-inferiority trial.

SETTING

Outpatients.

POPULATION

Patients affected by idiopathic PD without cognitive impairment, Hoehn and Yahr stage II-IV, Unified Parkinson's Disease Rating Scale motor section III ≥2, stable drug usage since at least 3 weeks.

METHODS

At the enrollment (T0), all subjects underwent a clinical/functional evaluation and the instrumental gait and postural analysis; then they were randomly assigned to the Study Group (SG) or Control Group (CG). Rehabilitation program consisted in 10 consecutive individual sessions (5 sessions/week for 2 consecutive weeks). Each session included 60 minutes of conventional physiotherapy plus 30 minutes of gait training by Q-Walk (SG) or by traditional visual cues (CG). Follow-up visits were scheduled at the end of the treatment (T1) and after 3 months (T2).

RESULTS

Fifty-two subjects were enrolled in the study, 26 in each group. The within-groups analysis showed a significant improvement in clinical scales and instrumental data at T1 and at T2, compared to baseline, in both groups. According to the between-group analysis, Q-Walk cueing system was not-inferior to the traditional cues for gait rehabilitation. The satisfaction questionnaire revealed that most subjects described the Q-Walk cueing system as simple, motivating and easily usable, possibly suitable for home use.

CONCLUSIONS

Data showed that motor rehabilitation of PD subjects performed by means of the new wearable Q-Walk cueing system was feasible and as effective as traditional cues in improving gait parameters and balance.

CLINICAL REHABILITATION IMPACT

Wearable devices can act as an additional rehabilitation strategy for long-term and continuous care, allowing patients to train intensively and extensively in household settings, favoring a tailor-made and personalized approach as well as remote monitoring.

Chronic Pallidal Local Field Potentials Are Associated With Dystonic Symptoms in Children

BACKGROUND

Novel deep brain stimulation devices can record local field potentials (LFPs), which represent the synchronous synaptic activity of neuronal populations. The clinical relevance of LFPs in patients with dystonia remains unclear.

OBJECTIVES

We sought to determine whether chronic LFPs recorded from the globus pallidus internus (GPi) were associated with symptoms of dystonia in children.

MATERIALS AND METHODS

Ten patients with heterogeneous forms of dystonia (genetic and acquired) were implanted with neurostimulators that recorded LFP spectral snapshots. Spectra were compared across parent-reported asymptomatic and symptomatic periods, with daily narrowband data superimposed in 24 one-hour bins.

RESULTS

Spectral power increased during periods of registered dystonic symptoms: mean increase = 102%, CI: (76.7, 132). Circadian rhythms within the LFP narrowband time series correlated with dystonic symptoms: for delta/theta-waves, correlation = 0.33, CI: (0.18, 0.47) and for alpha waves, correlation = 0.27, CI: (0.14, 0.40).

CONCLUSIONS

LFP spectra recorded in the GPi indicate a circadian pattern and are associated with the manifestation of dystonic symptoms.

A video-atlas of levodopa-induced dyskinesia in Parkinson's disease: terminology matters

Dyskinesia is a common complication of long-term levodopa therapy in patients with Parkinson's disease (PD), which often worsens the quality of life. It is usually dose-dependent and emerges possibly due to pulsatile stimulation of dopamine receptors. Delineating the pattern of dyskinesia is crucial for determining the most effective therapeutic approach, a task that often presents challenges for numerous neurologists. This article comprehensively describes various patterns of dyskinesia in PD patients and features video demonstration of some of the common forms of dyskinesia. We have used a real case scenario as an example to lead the discussion on the phenomenology, distinguishing features, and management of various types of dyskinesia. A comprehensive literature search was conducted in PubMed using "dyskinesia" as a keyword. The prototype case with videos highlights the differentiating features of dyskinesia along with the treatment strategies. A wide range of descriptive rubrics have been used for certain dyskinesia which are described in detail in this article. The newer types of dyskinesia associated with continuous dopaminergic stimulation in patients with advanced PD and their implications have been described. As there are distinct ways of managing various types of dyskinesia, understanding the phenomenology and chronology of dyskinesia is vital for the optimal management of dyskinetic PD patients. We suggest that dyskinesia should be classified broadly into peak-dose dyskinesia (PDD), biphasic dyskinesia (BD), and OFF-period dystonia. The occurrence of low-dose dyskinesia and complex dyskinesia of continuous dopaminergic treatments should be known to specialists and will require additional studies.

Freezing of gait in idiopathic normal pressure hydrocephalus

BACKGROUND

Reports of freezing of gait (FoG) in idiopathic normal pressure hydrocephalus (iNPH) are few and results are variable. This study's objective was to evaluate the frequency of FoG in a large cohort of iNPH patients, identify FoG-associated factors, and assess FoG's responsiveness to shunt surgery.

METHODS

Videotaped standardized gait protocols with iNPH patients pre- and post-shunt surgery (n = 139; median age 75 (71-79) years; 48 women) were evaluated for FoG episodes by two observers (Cohens kappa = 0.9, p < 0.001). FoG episodes were categorized. Mini-mental state examination (MMSE) and MRI white matter hyperintensities (WMH) assessment using the Fazekas scale were performed. CSF was analyzed for Beta-amyloid, Tau, and Phospho-tau. Patients with and without FoG were compared.

RESULTS

Twenty-two patients (16%) displayed FoG at baseline, decreasing to seven (8%) after CSF shunt surgery (p = 0.039). The symptom was most frequently exhibited during turning (n = 16, 73%). Patients displaying FoG were older (77.5 vs. 74.6 years; p = 0.029), had a slower walking speed (0.59 vs. 0.89 m/s; p < 0.001), a lower Tinetti POMA score (6.8 vs. 10.8; p < 0.001), lower MMSE score (21.3 vs. 24.0; p = 0.031), and longer disease duration (4.2 vs. 2.3 years; p < 0.001) compared to patients not displaying FoG. WMH or CSF biomarkers did not differ between the groups.

CONCLUSIONS

FoG is occurring frequently in iNPH patients and may be considered a typical feature of iNPH. FoG in iNPH was associated with higher age, longer disease duration, worse cognitive function, and a more unstable gait. Shunt surgery seems to improve the symptom.

Successful magnetic resonance-guided focused ultrasound treatment of tremor in patients with a skull density ratio of 0.4 or less

OBJECTIVE

The use of magnetic resonance-guided focused ultrasound (MRgFUS) for the treatment of tremor-related disorders and other novel indications has been limited by guidelines advocating treatment of patients with a skull density ratio (SDR) above 0.45 ± 0.05 despite reports of successful outcomes in patients with a low SDR (LSDR). The authors' goal was to retrospectively analyze the sonication strategies, adverse effects, and clinical and imaging outcomes in patients with SDR ≤ 0.4 treated for tremor using MRgFUS.

METHODS

Clinical outcomes and adverse effects were assessed at 3 and 12 months after MRgFUS. Outcomes and lesion location, volume, and shape characteristics (elongation and eccentricity) were compared between the SDR groups.

RESULTS

A total of 102 consecutive patients were included in the analysis, of whom 39 had SDRs ≤ 0.4. No patient was excluded from treatment because of an LSDR, with the lowest being 0.22. Lesioning temperatures (> 52°C) and therapeutic ablations were achieved in all patients. There were no significant differences in clinical outcome, adverse effects, lesion location, and volume between the high SDR group and the LSDR group. SDR was significantly associated with total energy (rho = -0.459, p < 0.001), heating efficiency (rho = 0.605, p < 0.001), and peak temperature (rho = 0.222, p = 0.025).

CONCLUSIONS

The authors' results show that treatment of tremor in patients with an LSDR using MRgFUS is technically possible, leading to a safe and lasting therapeutic effect. Limiting the number of sonications and adjusting the energy and duration to achieve the required temperature early during the treatment are suitable strategies in LSDR patients.

Proceedings of the 11th Annual Deep Brain Stimulation Think Tank: pushing the forefront of neuromodulation with functional network mapping, biomarkers for adaptive DBS, bioethical dilemmas, AI-guided neuromodulation, and translational advancements

The Deep Brain Stimulation (DBS) Think Tank XI was held on August 9-11, 2023 in Gainesville, Florida with the theme of "Pushing the Forefront of Neuromodulation". The keynote speaker was Dr. Nico Dosenbach from Washington University in St. Louis, Missouri. He presented his research recently published in Nature inn a collaboration with Dr. Evan Gordon to identify and characterize the somato-cognitive action network (SCAN), which has redefined the motor homunculus and has led to new hypotheses about the integrative networks underpinning therapeutic DBS. The DBS Think Tank was founded in 2012 and provides an open platform where clinicians, engineers, and researchers (from industry and academia) can freely discuss current and emerging DBS technologies, as well as logistical and ethical issues facing the field. The group estimated that globally more than 263,000 DBS devices have been implanted for neurological and neuropsychiatric disorders. This year's meeting was focused on advances in the following areas: cutting-edge translational neuromodulation, cutting-edge physiology, advances in neuromodulation from Europe and Asia, neuroethical dilemmas, artificial intelligence and computational modeling, time scales in DBS for mood disorders, and advances in future neuromodulation devices.

Neurodegeneration with Brain Iron Accumulation Disorders and Retinal Neurovascular Structure

BACKGROUND

The unique neurovascular structure of the retina has provided an opportunity to observe brain pathology in many neurological disorders. However, such studies on neurodegeneration with brain iron accumulation (NBIA) disorders are lacking.

OBJECTIVES

To investigate NBIA's neurological and ophthalmological manifestations.

METHODS

This cross-sectional study was conducted on genetically confirmed NBIA patients and an age-gender-matched control group. The thickness of retinal layers, central choroidal thickness (CCT), and capillary plexus densities were measured by spectral domain-optical coherence tomography (SD-OCT) and OCT angiography, respectively. The patients also underwent funduscopy, electroretinography (ERG), visual evoked potential (VEP), and neurological examination (Pantothenate-Kinase Associated Neurodegeneration-Disease Rating Scale [PKAN-DRS]). The generalized estimating equation model was used to consider inter-eye correlations.

RESULTS

Seventy-four patients' and 80 controls' eyes were analyzed. Patients had significantly decreased visual acuity, reduced inner or outer sectors of almost all evaluated layers, increased CCT, and decreased vessel densities, with abnormal VEP and ERG in 32.4% and 45.9%, respectively. There were correlations between visual acuity and temporal peripapillary nerve fiber layer (positive) and between PKAN-DRS score and disease duration (negative), and scotopic b-wave amplitudes (positive). When considering only the PKAN eyes, ONL was among the significantly decreased retinal layers, with no differences in retinal vessel densities. Evidence of pachychoroid was only seen in patients with Kufor Rakeb syndrome.

CONCLUSION

Observing pathologic structural and functional neurovascular changes in NBIA patients may provide an opportunity to elucidate the underlying mechanisms and differential retinal biomarkers in NBIA subtypes in further investigations. © 2023 International Parkinson and Movement Disorder Society.

Uncovering neuroanatomical correlates of impaired coordinated movement after pallidal deep brain stimulation

BACKGROUND

The loss of the ability to swim following deep brain stimulation (DBS), although rare, poses a worrisome risk of drowning. It is unclear what anatomic substrate and neural circuitry underlie this phenomenon. We report a case of cervical dystonia with lost ability to swim and dance during active stimulation of globus pallidus internus. We investigated the anatomical underpinning of this phenomenon using unique functional and structural imaging analysis.

METHODS

Tesla (3T) functional MRI (fMRI) of the patient was used during active DBS and compared with a cohort of four matched patients without this side effect. Structural connectivity mapping was used to identify brain network engagement by stimulation.

RESULTS

fMRI during stimulation revealed significant (Pbonferroni<0.0001) stimulation-evoked responses (DBS ON

CONCLUSIONS

These stimulation-induced impairments are likely a manifestation of a broader deficit in interlimb coordination mediated by stimulation effects on the SMA. This neuroanatomical underpinning can help inform future patient-specific stimulation and targeting.

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Key Words

• DYSTONIA
• ELECTRICAL STIMULATION
• FUNCTIONAL IMAGING
• MRI
• NEUROSURGERY

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MESH Headings

• Humans
• Globus Pallidus/diagnostic imaging
• Globus Pallidus/physiology
• Deep Brain Stimulation/adverse effects
• Deep Brain Stimulation/methods
• Treatment Outcome
• Magnetic Resonance Imaging

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Grants Collapse

Affiliation(s)

Brendan Santyr Division of Neurosurgery, University of Toronto, Toronto, Ontario, Canada
Aaron Loh Division of Neurosurgery, University of Toronto, Toronto, Ontario, Canada
Artur Vetkas Division of Neurosurgery, University of Toronto, Toronto, Ontario, Canada
Dave Gwun Division of Neurosurgery, University of Toronto, Toronto, Ontario, Canada
Wilson Kw Fung Edmond J. Safra Program in Parkinson's Disease and Morton and Gloria Shulman Movement Disorders Centre, Toronto Western Hospital, Toronto, Ontario, Canada
Shakeel Qazi Division of Neurosurgery, University of Toronto, Toronto, Ontario, Canada
Jurgen Germann Division of Neurosurgery, University of Toronto, Toronto, Ontario, Canada
Alexandre Boutet Division of Neurosurgery, University of Toronto, Toronto, Ontario, Canada Joint Department of Medical Imaging, Toronto Western Hospital, Toronto, Ontario, Canada
Can Sarica Division of Neurosurgery, University of Toronto, Toronto, Ontario, Canada
Andrew Yang Division of Neurosurgery, University of Toronto, Toronto, Ontario, Canada
Gavin Elias Division of Neurosurgery, University of Toronto, Toronto, Ontario, Canada
Suneil K Kalia Division of Neurosurgery, University of Toronto, Toronto, Ontario, Canada Krembil Brain Institute, University Health Network, Toronto, Ontario, Canada Center for Advancing Neurotechnological Innovation to Application (CRANIA), University Health Network, Toronto, Ontario, Canada
Alfonso Fasano Edmond J. Safra Program in Parkinson's Disease and Morton and Gloria Shulman Movement Disorders Centre, Toronto Western Hospital, Toronto, Ontario, Canada Krembil Brain Institute, University Health Network, Toronto, Ontario, Canada Center for Advancing Neurotechnological Innovation to Application (CRANIA), University Health Network, Toronto, Ontario, Canada Division of Neurology, University of Toronto, Toronto, Ontario, Canada
Andres M Lozano Division of Neurosurgery, University of Toronto, Toronto, Ontario, Canada Krembil Brain Institute, University Health Network, Toronto, Ontario, Canada

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Comparative neural correlates of DBS and MRgFUS lesioning for tremor control in essential tremor

BACKGROUND

Given high rates of early complications and non-reversibility, refined targeting is necessitated for magnetic resonance-guided focused ultrasound (MRgFUS) thalamotomy for essential tremor (ET). Selection of lesion location can be informed by considering optimal stimulation area from deep brain stimulation (DBS).

METHODS

118 patients with ET who received DBS (39) or MRgFUS (79) of the ventral intermediate nucleus (VIM) underwent stimulation/lesion mapping, probabilistic mapping of clinical efficacy and normative structural connectivity analysis. The efficacy maps were compared, which depict the relationship between stimulation/lesion location and clinical outcome.

RESULTS

Efficacy maps overlap around the VIM ventral border and encompass the dentato-rubro-thalamic tract. While the MRgFUS map extends inferiorly into the posterior subthalamic area, the DBS map spreads inside the VIM antero-superiorly.

CONCLUSION

Comparing the efficacy maps of DBS and MRgFUS suggests a potential alternative location for lesioning, more antero-superiorly. This may reduce complications, without sacrificing efficacy, and individualise targeting.

TRIAL REGISTRATION NUMBER

NCT02252380.

Another Step Forward for Freezing of Gait in Parkinson's Disease

The study "A spinal cord neuroprosthesis for locomotor deficits due to Parkinson's disease" by Milekovic et al. introduces a novel neuroprosthesis for treating locomotor deficits in late-stage Parkinson's disease (PD). This approach employs an epidural spinal array targeting dorsal roots and electromyography to create a spatiotemporal map of muscle activation, aiming to restore natural gait patterns. Significant improvements in gait freezing and balance were observed in both non-human primate models and a human patient, resulting in improved mobility and quality of life. This innovative method, integrating real-time feedback and non-invasive motor intention decoding, marks a significant advancement in PD treatment.

Evaluating the ability of a predictive vision-based machine learning model to measure changes in gait in response to medication and DBS within individuals with Parkinson's disease

INTRODUCTION

Gait impairments in Parkinson's disease (PD) are treated with dopaminergic medication or deep-brain stimulation (DBS), although the magnitude of the response is variable between individuals. Computer vision-based approaches have previously been evaluated for measuring the severity of parkinsonian gait in videos, but have not been evaluated for their ability to identify changes within individuals in response to treatment. This pilot study examines whether a vision-based model, trained on videos of parkinsonism, is able to detect improvement in parkinsonian gait in people with PD in response to medication and DBS use.

METHODS

A spatial-temporal graph convolutional model was trained to predict MDS-UPDRS-gait scores in 362 videos from 14 older adults with drug-induced parkinsonism. This model was then used to predict MDS-UPDRS-gait scores on a different dataset of 42 paired videos from 13 individuals with PD, recorded while ON and OFF medication and DBS treatment during the same clinical visit. Statistical methods were used to assess whether the model was responsive to changes in gait in the ON and OFF states.

RESULTS

The MDS-UPDRS-gait scores predicted by the model were lower on average (representing improved gait; p = 0.017, Cohen's d = 0.495) during the ON medication and DBS treatment conditions. The magnitude of the differences between ON and OFF state was significantly correlated between model predictions and clinician annotations (p = 0.004). The predicted scores were significantly correlated with the clinician scores (Kendall's tau-b = 0.301, p = 0.010), but were distributed in a smaller range as compared to the clinician scores.

CONCLUSION

A vision-based model trained on parkinsonian gait did not accurately predict MDS-UPDRS-gait scores in a different PD cohort, but detected weak, but statistically significant proportional changes in response to medication and DBS use. Large, clinically validated datasets of videos captured in many different settings and treatment conditions are required to develop accurate vision-based models of parkinsonian gait.

Use of cortical volume to predict response to temporary CSF drainage in patients with idiopathic normal pressure hydrocephalus

OBJECTIVE

Temporary drainage of CSF with lumbar puncture or lumbar drainage has a high predictive value for identifying patients with suspected idiopathic normal pressure hydrocephalus (iNPH) who may benefit from ventriculoperitoneal shunt insertion. However, it is unclear what differentiates responders from nonresponders. The authors hypothesized that nonresponders to temporary CSF drainage would have patterns of reduced regional gray matter volume (GMV) as compared with those of responders. The objective of the current investigation was to compare regional GMV between temporary CSF drainage responders and nonresponders. Machine learning using extracted GMV was then used to predict outcomes.

METHODS

This retrospective cohort study included 132 patients with iNPH who underwent temporary CSF drainage and structural MRI. Demographic and clinical variables were examined between groups. Voxel-based morphometry was used to calculate GMV across the brain. Group differences in regional GMV were assessed and correlated with change in results on the Montreal Cognitive Assessment (MoCA) and gait velocity. A support vector machine (SVM) model that used extracted GMV values and was validated with leave-one-out cross-validation was used to predict clinical outcome.

RESULTS

There were 87 responders and 45 nonresponders. There were no group differences in terms of age, sex, baseline MoCA score, Evans index, presence of disproportionately enlarged subarachnoid space hydrocephalus, baseline total CSF volume, or baseline white matter T2-weighted hyperintensity volume (p > 0.05). Nonresponders demonstrated decreased GMV in the right supplementary motor area (SMA) and right posterior parietal cortex as compared with responders (p < 0.001, p < 0.05 with false discovery rate cluster correction). GMV in the posterior parietal cortex was associated with change in MoCA (r2 = 0.075, p < 0.05) and gait velocity (r2 = 0.076, p < 0.05). Response status was classified by the SVM with 75.8% accuracy.

CONCLUSIONS

Decreased GMV in the SMA and posterior parietal cortex may help identify patients with iNPH who are unlikely to benefit from temporary CSF drainage. These patients may have limited capacity for recovery due to atrophy in these regions that are known to be important for motor and cognitive integration. This study represents an important step toward improving patient selection and predicting clinical outcomes in the treatment of iNPH.

Adult Phenotype of SYNGAP1-DEE

Background and Objectives

SYNGAP1 variants are associated with rare developmental and epileptic encephalopathies (DEEs). Although SYNGAP1-related childhood phenotypes are well characterized, the adult phenotype remains ill-defined. We sought to investigate phenotypes and outcomes in adults with SYNGAP1 variants and epilepsy.

Methods

Patients 18 years or older with DEE carrying likely pathogenic and pathogenic (LP/P) SYNGAP1 variants were recruited through physicians' practices and patient organization groups. We used standardized questionnaires to evaluate current seizures, medication use, sleep, gastrointestinal symptoms, pain response, gait, social communication disorder and adaptive skills of patients. We also assessed caregiver burden.

Results

Fourteen unrelated adult patients (median: 21 years, range: 18-65 years) with SYNGAP1-DEE were identified, 11 with novel and 3 with known LP/P SYNGAP1 de novo variants. One patient with a partial exon 3 deletion had greater daily living skills and social skills than others with single-nucleotide variants. Ten of 14 (71%) patients had drug-resistant seizures, treated with a median of 2 antiseizure medications. All patients (100%) had abnormal pain processing. Sleep disturbances, social communication disorders, and aggressive/self-injurious behaviors were each reported in 86% of patients. Only half of adults could walk with minimal or no assistance. Toileting was normal in 29%, and 71% had constipation. No adult patients could read or understand verbal material at a sixth-grade level or higher. Aggressive/self-injurious behaviors were leading cause of caregiver burden. The oldest patient was aged 65 years; although nonambulant, she had walked independently when younger.

Discussion

Seventy-one percent of patients with SYNGAP1-DEEs continue to have seizures when adults. Nonseizure comorbidities, especially aggression and self-injurious behaviors, are major management challenges in adults with SYNGAP1-DEE. Only 50% of adults can ambulate with minimal or no assistance. Almost all adult patients depend on caregivers for many activities of daily living. Prompt diagnostic genetic testing of adults with DEE can inform clinical care and guide outcomes of precision therapies.

Deep Brain Stimulation of the Globus Pallidus Internus and Externus in Multiple System Atrophy

BACKGROUND

Multiple system atrophy with parkinsonism (MSA-P) is a progressive condition with no effective treatment.

OBJECTIVE

The aim of this study was to describe the safety and efficacy of deep brain stimulation (DBS) of globus pallidus pars interna and externa in a cohort of patients with MSA-P.

METHODS

Six patients were included. Changes in Movement Disorders Society Unified Parkinson's Disease Rating Scale Part III (MDS-UPDRS III), Parkinson's Disease Questionnaire (PDQ-39) scores, and levodopa equivalent daily dose were compared before and after DBS. Electrode localization and volume tissue activation were calculated.

RESULTS

DBS surgery did not result in any major adverse events or intraoperative complications. Overall, no differences in MDS-UPDRS III scores were demonstrated (55.2 ± 17.6 preoperatively compared with 67.3 ± 19.2 at 1 year after surgery), although transient improvement in mobility and dyskinesia was reported in some subjects.

CONCLUSIONS

Globus pallidus pars interna and externa DBS for patients with MSA-P did not result in major complications, although it did not provide significant clinical benefit as measured by MDS-UPDRS III. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Gait Analysis in Idiopathic Normal Pressure Hydrocephalus: A Meta-Analysis

Background

Gait analysis objectively quantifies gait impairment in idiopathic normal pressure hydrocephalus (iNPH), may improve diagnosis and evaluation for surgical candidacy.

Objectives

This meta-analysis aims to understand which objective gait parameters improve after tap-test (TT) and CSF shunt surgery (CSS), also comparing responders (R) with non-responders (NR) and to assess if gait restores within the range of healthy controls after procedures.

Methods

Studies enrolling iNPH with at least one instrumented gait measure were selected. Three time points of gait assessment were defined: PRE, POST-TT, and POST-CSS. Gait velocity, cadence, step length, stride length, and double limb support time were evaluated. Patients were categorized based on responsiveness to CSF diversion procedures.

Results

Seventeen studies including 527 patients were selected. iNPH improved significantly in almost all gait parameters POST-TT, and to a greater extent POST-CSS. Gait parameters consistently discriminated iNPH from healthy controls. Despite the aforementioned improvements, iNPH's gait did not completely normalize after CSF diversion procedures. Meta-regression analysis also revealed that TT's effect on gait velocity plateaus after 24-48 hr and returns to baseline in 90-100 hr.

Conclusions

Gait analysis is a reliable quantitative instrument to assess gait impairment in iNPH, demarking a net differentiation from healthy controls, according to the notion that the iNPH CSF dynamic alteration also leads to an irreversible damage. Specific gait parameters improve among TT-R, providing an opportunity to select patients that will respond to CSS. Future studies validating a standardized reporting method including criteria of responsiveness, specific gait parameters, and timeframe of assessment are needed.

Predictors and Pathophysiology of Axial Postural Abnormalities in Parkinsonism: A Scoping Review

Background

Postural abnormalities involving the trunk are referred to as axial postural abnormalities and can be observed in over 20% of patients with Parkinson's disease (PD) and in atypical parkinsonism. These symptoms are highly disabling and frequently associated with back pain and a worse quality of life in PD. Despite their frequency, little is known about the pathophysiology of these symptoms and scant data are reported about their clinical predictors, making it difficult to prompt prevention strategies.

Objectives

We conducted a scoping literature review of clinical predictors and pathophysiology of axial postural abnormalities in patients with parkinsonism to identify key concepts, theories and evidence on this topic.

Methods

We applied a systematic approach to identify studies, appraise quality of evidence, summarize main findings, and highlight knowledge gaps.

Results

Ninety-two articles were reviewed: 25% reported on clinical predictors and 75% on pathophysiology. Most studies identified advanced disease stage and greater motor symptoms severity as independent clinical predictors in both PD and multiple system atrophy. Discrepant pathophysiology data suggested different potential central and peripheral pathogenic mechanisms.

Conclusions

The recognition of clinical predictors and pathophysiology of axial postural abnormalities in parkinsonism is far from being elucidated due to literature bias, encompassing different inclusion criteria and measurement tools and heterogeneity of patient samples. Most studies identified advanced disease stage and higher burden of motor symptoms as possible clinical predictors. Pathophysiology data point toward many different (possibly non-mutually exclusive) mechanisms, including dystonia, rigidity, proprioceptive and vestibular impairment, and higher cognitive deficits.

Trends and disparities in deep brain stimulation utilization in the United States: a Nationwide Inpatient Sample analysis from 1993 to 2017

Background

Deep brain stimulation (DBS) is an approved treatment option for Parkinson's Disease (PD), essential tremor (ET), dystonia, obsessive-compulsive disorder and epilepsy in the United States. There are disparities in access to DBS, and clear understanding of the contextual factors driving them is important. Previous studies aimed at understanding these factors have been limited by single indications or small cohort sizes. The aim of this study is to provide an updated and comprehensive analysis of DBS utilization for multiple indications to better understand the factors driving disparities in access.

Methods

The United States based National Inpatient Sample (NIS) database was utilized to analyze the surgical volume and trends of procedures based on indication, using relevant ICD codes. Predictors of DBS use were analyzed using a logistic regression model. DBS-implanted patients in each indication were compared based on the patient-, hospital-, and outcome-related variables.

Findings

Our analysis of 104,356 DBS discharges from 1993 to 2017 revealed that the most frequent indications for DBS were PD (67%), ET (24%), and dystonia (4%). Although the number of DBS procedures has consistently increased over the years, radiofrequency ablation utilization has significantly decreased to only a few patients per year since 2003. Negative predictors for DBS utilization in PD and ET cohorts included age increase and female sex, while African American status was a negative predictor across all cohorts. Significant differences in patient-, hospital-, and outcome-related variables between DBS indications were also determined.

Interpretation

Demographic and socioeconomic-based disparities in DBS use are evident. Although racial disparities are present across all indications, other disparities such as age, sex, wealth, and insurance status are only relevant in certain indications.

Funding

This work was supported by Alan & Susan Hudson Cornerstone Chair in Neurosurgery at University Health Network.

Deep Brain Stimulation for Refractory Status Dystonicus in Children: Multicenter Case Series and Systematic Review

OBJECTIVE

We sought to better understand the workflow, outcomes, and complications of deep brain stimulation (DBS) for pediatric status dystonicus (SD). We present a systematic review, alongside a multicenter case series of pediatric patients with SD treated with DBS.

METHODS

We collected individual data regarding treatment, stimulation parameters, and dystonia severity for a multicenter case series (n = 8) and all previously published cases (n = 77). Data for case series were used to create probabilistic voxelwise maps of stimulated tissue associated with dystonia improvement.

RESULTS

In our institutional series, DBS was implanted a mean of 25 days after SD onset. Programming began a mean of 1.6 days after surgery. All 8 patients in our case series and 73 of 74 reported patients in the systematic review had resolution of their SD with DBS, most within 2 to 4 weeks of surgery. Mean follow-up for patients in the case series was 16 months. DBS target for all patients in the case series and 68 of 77 in our systematic review was the globus pallidus pars interna (GPi). In our case series, stimulation of the posterior-ventrolateral GPi was associated with improved dystonia. Mean dystonia improvement was 32% and 51% in our institutional series and systematic review, respectively. Mortality was 4% in the review, which is lower than reported for treatment with pharmacotherapy alone (10-12.5%).

INTERPRETATION

DBS is a feasible intervention with potential to reverse refractory pediatric SD and improve survival. More work is needed to increase awareness of DBS in this setting, so that it can be implemented in a timely manner. ANN NEUROL 2023.

The Role of Levodopa Challenge in Predicting the Outcome of Subthalamic Deep Brain Stimulation

Background

Deep brain stimulation of the subthalamic nucleus (STN-DBS) is an effective and evidence-based treatment for idiopathic Parkinson's disease (iPD). A minority of patients does not sufficiently benefit from STN-DBS.

Objective

The predictive validity of the levodopa challenge for individual patients is analyzed.

Methods

Data from patients assessed with a preoperative Levodopa-test and a follow-up examination (mean ± standard deviation: 9.15 months ±3.39) from Kiel (n = 253), Berlin (n = 78) and Toronto (n = 98) were studied. Insufficient DBS outcome was defined as an overall UPDRS-III reduction <33% compared to UPDRS-III in med-off at baseline or alternatively if the minimal clinically important improvement of 5 points was not reached. Single UPDRS-items and sub-scores were dichotomized. Following exploratory analysis, we trained supervised regression- and classification models for outcome prediction.

Results

Data analysis confirmed significant correlation between the absolute UPDRS-III reduction during Levodopa challenge and after stimulation. But individual improvement was inaccurately predicted with a large range of up to 30 UPDRS III points. Further analysis identified preoperative UPDRS-III/med-off-scores and preoperative Levodopa-improvement as most influential factors. The models for UPDRS-III and sub-scores improvement achieved comparably low accuracy.

Conclusions

With large prediction intervals, the Levodopa challenge use for patient counseling is limited, though remains important for excluding non-responders to Levodopa. Despite these deficiencies, the current practice of patient selection is highly successful and builds not only on the Levodopa challenge. However, more specific motor tasks and further paraclinical tools for prediction need to be developed.

The Role of Helicobacter pylori and Small Intestinal Bacterial Overgrowth in Parkinson's Disease

Parkinson's disease (PD) is a common neurodegenerative disorder whose etiology remains largely unexplained. Several studies have aimed to describe a causative effect in the interactions between the gastrointestinal tract and the brain, for both PD pathogenesis and disease course. However, the results have been controversial. Helicobacter pylori and small intestinal bacterial overgrowth (SIBO) are theorized to be agents capable of triggering chronic proinflammatory changes with a possible neurotoxic effect, as well as a cause of erratic L-dopa response in PD patients. This review evaluates the individual and possibly synergistic influence of H. pylori and SIBO on PD, to provide an opportunity to consider prospective therapeutic approaches.

Punding in Parkinson's Disease: An Update

Background

Punding is a stereotyped behavior characterized by an intense fascination with a complex, excessive, non-goal oriented, repetitive activity affecting individuals with Parkinson's disease (PD) on dopamine replacement therapy (DRT).

Objectives

In 2010, we published the first review focused on the pathophysiology of punding. This study aims to systematically review the literature of the past decade on punding in PD, particularly focusing on the clinical features, underlying pathophysiological mechanisms, and treatment.

Methods

Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, we searched PubMed, Embase, and APA PsycInfo for articles published between July 1, 2010 and March 19, 2022. The search strategy included: (punding) AND (parkinson*).

Results

Of 256 studies identified, 29 were eligible for inclusion with 19 original research articles and 10 case reports. This review confirmed that predictors of punding in PD are higher doses of DRT, younger age, male sex, and increasing disease severity. We also found an association between punding and psychiatric and/or cognitive symptoms. Neuroimaging studies have showed that punding in PD is associated with a disconnection between midbrain, limbic and white matter tracts projecting to the frontal cortices and a breakdown of the connectivity among the crucial nodes of the reward circuit. Low-frequency repetitive transcranial magnetic stimulation on the dorsolateral prefrontal cortex has been shown to produce a transient beneficial effect in PD patients with punding.

Conclusion

In conclusion, although the clinical features of punding have been established, in the past 12 years, we gained a better understanding of the pathophysiological mechanisms of punding, mainly thanks to magnetic resonance imaging techniques.

Essential Tremor - Deep Brain Stimulation vs. Focused Ultrasound

INTRODUCTION

Essential Tremor (ET) is one of the most common tremor syndromes typically presented as action tremor, affecting mainly the upper limbs. In at least 30-50% of patients, tremor interferes with quality of life, does not respond to first-line therapies and/or intolerable adverse effects may occur. Therefore, surgery may be considered.

AREAS COVERED

In this review, the authors discuss and compare unilateral ventral intermedius nucleus deep brain stimulation (VIM DBS) and bilateral DBS with Magnetic Resonance-guided Focused Ultrasound (MRgFUS) thalamotomy, which comprises focused acoustic energy generating ablation under real-time MRI guidance. Discussion includes their impact on tremor reduction and their potential complications. Finally, the authors provide their expert opinion.

EXPERT OPINION

DBS is adjustable, potentially reversible and allows bilateral treatments; however, it is invasive requires hardware implantation, and has higher surgical risks. Instead, MRgFUS is less invasive, less expensive, and requires no hardware maintenance. Beyond these technical differences, the decision should also involve the patient, family, and caregivers.

Comparison of Monopolar Review to Fixed Parameter Fractionation in Deep Brain Stimulation

Background

Technological advancements in deep brain stimulation (DBS) require methodological changes in programming. Fractionalization poses significant practical challenges for the most common approach for assessing DBS efficacy, monopolar review (MR).

Objectives

Two DBS programming methods: MR and fixed parameter vertical and horizontal fractionalization (FPF) were compared.

Methods

A two-phase process of vertical and horizontal FPF was performed. MR was conducted thereafter. After a short wash-out period, both optimal configurations determined by MR and FPF were tested in a double-blind randomized manner.

Results

Seven PD patients were enrolled, providing 11 hemispheres to compare the two conditions. In all subjects, the blinded examiner selected a directional or fractionalization configuration. There was no significant difference in clinical benefits between MR and FPF. FPF was the preferred method for initial programming as selected by subject and clinician.

Conclusions

FPF programming is a viable and efficient methodology that may be incorporated into clinical practice.

Different types of tremor and myoclonus in an atypical case of shaking upon standing

Shaking upon standing is associated with a spectrum of different conditions. We describe an unusual case with a combination of slow orthostatic tremor, orthostatic myoclonus, and parkinsonism. The case illustrates the utility of electrophysiology for precise characterization of physical findings to establish the diagnosis.

Genetics of mirror movements identifies a multifunctional complex required for Netrin-1 guidance and lateralization of motor control

Mirror movements (MM) disorder is characterized by involuntary movements on one side of the body that mirror intentional movements on the opposite side. We performed genetic characterization of a family with autosomal dominant MM and identified ARHGEF7, a RhoGEF, as a candidate MM gene. We found that Arhgef7 and its partner Git1 bind directly to Dcc. Dcc is the receptor for Netrin-1, an axon guidance cue that attracts commissural axons to the midline, promoting the midline crossing of axon tracts. We show that Arhgef7 and Git1 are required for Netrin-1-mediated axon guidance and act as a multifunctional effector complex. Arhgef7/Git1 activates Rac1 and Cdc42 and inhibits Arf1 downstream of Netrin-1. Furthermore, Arhgef7/Git1, via Arf1, mediates the Netrin-1-induced increase in cell surface Dcc. Mice heterozygous for Arhgef7 have defects in commissural axon trajectories and increased symmetrical paw placements during skilled walking, a MM-like phenotype. Thus, we have delineated how ARHGEF7 mutation causes MM.

Levodopa Dose Equivalency in Parkinson's Disease: Updated Systematic Review and Proposals

BACKGROUND

To compare drug regimens across clinical trials in Parkinson's disease (PD) conversion formulae between antiparkinsonian drugs have been developed. These are reported in relation to levodopa as the benchmark drug in PD pharmacotherapy as 'levodopa equivalent dose' (LED). Currently, the LED conversion formulae proposed in 2010 by Tomlinson et al. based on a systematic review are predominantly used. However, new drugs with established and novel mechanisms of action and novel formulations of longstanding drugs have been developed since 2010. Therefore, consensus proposals for updated LED conversion formulae are needed.

OBJECTIVES

To update LED conversion formulae based on a systematic review.

METHODS

The MEDLINE, CENTRAL, and Embase databases were searched from January 2010 to July 2021. Additionally, in a standardized process according to the GRADE grid method, consensus proposals were issued for drugs with scarce data on levodopa dose equivalency.

RESULTS

The systematic database search yielded 3076 articles of which 682 were eligible for inclusion in the systematic review. Based on these data and the standardized consensus process, we present proposals for LED conversion formulae for a wide range of drugs that are currently available for the pharmacotherapy of PD or are expected to be introduced soon.

CONCLUSIONS

The LED conversion formulae issued in this Position Paper will serve as a research tool to compare the equivalence of antiparkinsonian medication across PD study cohorts and facilitate research on the clinical efficacy of pharmacological and surgical treatments as well as other non-pharmacological interventions in PD. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Hemiatrophy-hemiparkinsonism and Poland syndrome: A causative or coincidental association?

Despite various neurologic symptoms of Poland syndrome (PS), parkinsonism was never reported in PS, and the response to the treatment of parkinsonism was not studied before. We report a case of ipsilateral parkinsonism in PS, similar to hemiatrophy-hemiparkinsonism, with a good response to levodopa and subthalamic deep brain stimulation.

Cognition affects gait adaptation after split-belt treadmill training in Parkinson's disease

BACKGROUND

Split-belt treadmill (SBTM) training has been proposed to improve gait symmetry and overall gait performance of patients with Parkinson's disease (PD).

OBJECTIVES

To determine whether patient's baseline features affect gait adaptation to SBTM in PD with freezing of gait (FOG).

METHODS

Twenty participants with idiopathic PD and treatment-resistant FOG underwent several clinical assessments including the Toronto Cognitive Assessment (TorCA) prior to treadmill training. Velocity of the treadmill was adjusted to over-ground walking speed. During SBTM training, the belt velocity on the least-affected side was reduced by 25%.

RESULTS

Participants who adapted to SBTM training demonstrated cognitively intact TorCA scores (p < 0.001), particularly intact working memory (p < 0.001). After-effects correlated with normal total TorCA (p = 0.02), working memory and visuospatial (p < 0.001) function.

CONCLUSIONS

Cognitive impairment, particularly impaired working memory, reduces gait adaptation and after-effects in PD with FOG. This is informative for trials studying prolonged effects of SBTM training in FOG.

Functional disorders as a common motor manifestation of COVID-19 infection or vaccination

BACKGROUND AND PURPOSE

There have been over 500 million confirmed cases of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), also known as coronavirus disease 2019 (COVID-19), across the globe. To date, a broad spectrum of neurological manifestations following acute infections as well as COVID-19 vaccines have been reported. The aim of this study was to describe the spectrum of neurological manifestations seen in the 'COVID-19 clinic' established in a tertiary Movement Disorders clinic.

METHODS

In this consecutive case-series study over the period March 2020-January 2022, clinical information regarding demographic data, clinical history and examination findings, investigation results and video recordings of outpatients with motor manifestations associated with COVID-19 infection or vaccination were reviewed.

RESULTS

Twenty-one adult patients were reviewed in this ad hoc clinic at Toronto Western Hospital. The majority of the patients were female (76%) and the mean (range) age was 50.7 ± 17.2 (21-80) years. Nine patients (43%) presented with motor manifestations following COVID-19 infection. Twelve patients (57%) developed neurological symptoms following at least one dose of the mRNA or viral vector-based COVID-19 vaccine. The most common manifestation observed was a functional movement disorder (43%). The vaccine group demonstrated a higher number of functional disorders compared to the infection group (58% vs. 22%; p = 0.08).

CONCLUSION

Functional motor manifestations can be associated with COVID-19 and are likely to be under-reported. In view of the co-existence of functional symptoms, movement disorders and mental health conditions observed in this study, we would advocate the use of dedicated COVID-19 Neurology clinics with full access to an experienced multidisciplinary team.

Trial of Globus Pallidus Focused Ultrasound Ablation in Parkinson's Disease

BACKGROUND

Unilateral focused ultrasound ablation of the internal segment of globus pallidus has reduced motor symptoms of Parkinson's disease in open-label studies.

METHODS

We randomly assigned, in a 3:1 ratio, patients with Parkinson's disease and dyskinesias or motor fluctuations and motor impairment in the off-medication state to undergo either focused ultrasound ablation opposite the most symptomatic side of the body or a sham procedure. The primary outcome was a response at 3 months, defined as a decrease of at least 3 points from baseline either in the score on the Movement Disorders Society-Unified Parkinson's Disease Rating Scale, part III (MDS-UPDRS III), for the treated side in the off-medication state or in the score on the Unified Dyskinesia Rating Scale (UDysRS) in the on-medication state. Secondary outcomes included changes from baseline to month 3 in the scores on various parts of the MDS-UPDRS. After the 3-month blinded phase, an open-label phase lasted until 12 months.

RESULTS

Of 94 patients, 69 were assigned to undergo ultrasound ablation (active treatment) and 25 to undergo the sham procedure (control); 65 patients and 22 patients, respectively, completed the primary-outcome assessment. In the active-treatment group, 45 patients (69%) had a response, as compared with 7 (32%) in the control group (difference, 37 percentage points; 95% confidence interval, 15 to 60; P = 0.003). Of the patients in the active-treatment group who had a response, 19 met the MDS-UPDRS III criterion only, 8 met the UDysRS criterion only, and 18 met both criteria. Results for secondary outcomes were generally in the same direction as those for the primary outcome. Of the 39 patients in the active-treatment group who had had a response at 3 months and who were assessed at 12 months, 30 continued to have a response. Pallidotomy-related adverse events in the active-treatment group included dysarthria, gait disturbance, loss of taste, visual disturbance, and facial weakness.

CONCLUSIONS

Unilateral pallidal ultrasound ablation resulted in a higher percentage of patients who had improved motor function or reduced dyskinesia than a sham procedure over a period of 3 months but was associated with adverse events. Longer and larger trials are required to determine the effect and safety of this technique in persons with Parkinson's disease. (Funded by Insightec; ClinicalTrials.gov number, NCT03319485.).