Sustained quality-of-life improvements over 10 years after deep brain stimulation for dystonia

Cell-class-specific electric field entrainment of neural activity

Electric fields affect the activity of neurons and brain circuits, yet how this happens at the cellular level remains enigmatic. Lack of understanding of how to stimulate the brain to promote or suppress specific activity significantly limits basic research and clinical applications. Here, we study how electric fields impact subthreshold and spiking properties of major cortical neuronal classes. We find that neurons in the rodent and human cortex exhibit strong, cell-class-dependent entrainment that depends on stimulation frequency. Excitatory pyramidal neurons, with their slower spike rate, entrain to both slow and fast electric fields, while inhibitory classes like Pvalb and Sst (with their fast spiking) predominantly phase-lock to fast fields. We show that this spike-field entrainment is the result of two effects: non-specific membrane polarization occurring across classes and class-specific excitability properties. Importantly, these properties are present across cortical areas and species. These findings allow for the design of selective and class-specific neuromodulation.

Deep Brain Stimulation for Orthostatic Tremor: An Observational Study

BACKGROUND

Primary orthostatic tremor (OT) can affect patients' life. Treatment of OT with deep brain stimulation (DBS) of the thalamic ventral intermediate nucleus (Vim) is described in a limited number of patients. The Vim and posterior subthalamic area (PSA) can be targeted in a single trajectory, allowing both stimulation of the Vim and/or dentatorubrothalamic tract (DRT). In essential tremor this is currently often used with positive effects.

OBJECTIVE

To evaluate the efficacy of Vim/DRT-DBS in OT-patients, based on standing time and Quality of Life (QoL), also on the long-term. Furthermore, to relate stimulation of the Vim and DRT, medial lemniscus (ML) and pyramidal tract (PT) to beneficial clinical and side-effects.

METHODS

Nine severely affected OT-patients received bilateral Vim/DRT-DBS. Primary outcome measure was standing time; secondary measures included self-reported measures, neurophysiological measures, structural analyses, surgical complications, stimulation-induced side-effects, and QoL up to 56 months. Stimulation of volume of tissue activated (VTA) were related to outcome measures.

RESULTS

Average maximum standing time increased from 41.0 s ± 51.0 s to 109.3 s ± 65.0 s after 18 months, with improvements measured in seven of nine patients. VTA (n = 7) overlapped with the DRT in six patients and with the ML and/or PT in six patients. All patients experienced side-effects and QoL worsened during the first year after surgery, which improved again during long-term follow-up, although remaining below age-related normal values. Most patients reported a positive effect of DBS.

CONCLUSION

Vim/DRT-DBS improved standing time in patients with severe OT. Observed side-effects are possibly related to stimulation of the ML and PT.

Cell class-specific electric field entrainment of neural activity

Electric fields affect the activity of neurons and brain circuits, yet how this interaction happens at the cellular level remains enigmatic. Lack of understanding on how to stimulate the human brain to promote or suppress specific activity patterns significantly limits basic research and clinical applications. Here we study how electric fields impact the subthreshold and spiking properties of major cortical neuronal classes. We find that cortical neurons in rodent neocortex and hippocampus as well as human cortex exhibit strong and cell class-dependent entrainment that depends on the stimulation frequency. Excitatory pyramidal neurons with their typically slower spike rate entrain to slow and fast electric fields, while inhibitory classes like Pvalb and SST with their fast spiking predominantly phase lock to fast fields. We show this spike-field entrainment is the result of two effects: non-specific membrane polarization occurring across classes and class-specific excitability properties. Importantly, these properties of spike-field and class-specific entrainment are present in cells across cortical areas and species (mouse and human). These findings open the door to the design of selective and class-specific neuromodulation technologies.

Deep brain stimulation for atypical parkinsonism: A systematic review on efficacy and safety

BACKGROUND

Atypical Parkinsonisms (APs) -including progressive supranuclear palsy (PSP), multiple system atrophy (MSA), and dementia with Lewy bodies (DLB)- are neurodegenerative diseases lacking satisfying symptomatic therapies. Deep Brain Stimulation (DBS) is an established neurosurgical option for advanced Parkinson disease (PD). Although DBS effectiveness in PD fed expectations for the treatment of APs, DBS is still not recommended for APs on the basis of expert consensus and lack of clinical trials.

OBJECTIVE

In this systematic review, we sought to analyze current evidence on the safety and efficacy of DBS in APs, discussing clinical indications, anatomical targets, and ethical issues.

METHODS

Following the PRISMA guidelines, we systematically searched PubMed for studies reporting the outcome of patients with APs treated with DBS.

RESULTS

We identified 25 eligible studies for a total of 66 patients with APs treated with DBS: 31 PSP, 22 MSA, 12 DLB, 1 unspecified parkinsonism with tongue tremor. Targeted nuclei were subthalamic nucleus (STN), globus pallidus pars-interna (GPi), pedunculopontine nucleus (PPN), and nucleus basalis of Meynert (nbM). Only 3/25 studies were randomized controlled trials, and most studies showed a high risk of bias.

CONCLUSION

Taking into account study biases and confounding factors, current evidence does not support the use of DBS in APs. However, some interesting insights arise from the literature, such as the high frequency of cognitive/neurobehavioral issues in MSA patients treated with STN-DBS, the low frequency of complications in trials of nbM-DBS for DLB, and the possible good response of dystonic symptoms in PSP with GPi DBS.

Long term follow-up results of deep brain stimulation of the Globus pallidus interna in pediatric patients with DYT1-positive dystonia

OBJECTIVES

Primary generalized dystonia (PGD) due to heterozygous torsin 1A (TOR1A) gene mutation (DYT1) is a childhood onset dystonia with rapid deterioration of symptoms, leading to severe disability in adolescence. Globus pallidus interna deep brain stimulation (GPi-DBS) has been shown to provide significant improvement in these cases.

METHODS

This was a retrospective study of TOR1A mutation positive dystonia patients, conducted at a university hospital from 2006 to 2018. Burke-Fahn-Marsden Dystonia Rating Scale (BFM-DRS) was used to evaluate dystonia severity before and after surgery. Emergence of postsurgical parkinsonian symptoms was evaluated using the Unified Parkinson Disease Rating Scale (UPDRS) part III. Montreal Cognitive Assessment (MOCA) was applied to assess cognitive dysfunction. SPSS version 18 was used for data analysis.

RESULTS

Eleven patients entered for analysis with an average age of 22.36 (±3.35) years (range: 18-28). Seven patients (63.6 %) were female. Mean follow-up period was 8.72 (±0.87). Difference between baseline and most recent BFM scores was significant (disability: 10.5 ±4.52 versus 2.09 (±3.20), P: 0.001; severity: 48.45 (±17.88) versus 9.36 (±10.47), P<0.001). The mean MOCA and UPDRS III scores after 7-9 years of DBS were 27.18 (±2.99), and 6.09 (±4.15), respectively.

CONCLUSION

Our experience confirms that GPi-DBS in pediatric patients with DYT1 dystonia is overall successful, with significant and long-lasting positive effects on motor and cognitive functions. There was no prominent side effect in long-term follow up.

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

BACKGROUND

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Importance of the initial response to GPi deep brain stimulation in dystonia: A nine year quality of life study

BACKGROUND

Long-term efficacy of deep brain stimulation (DBS) on health-related quality-of-life (HRQoL) for isolated dystonia is not well established. This study aims to determine the long-term impact of DBS on HRQoL outcomes and identify clinical predictors.

METHODS

We retrospectively investigated 16 inherited or idiopathic isolated dystonia patients treated with bilateral globus pallidus internus DBS who were followed beyond 9 years at our center. The cohort consisted of 9 males, 7 females; 10 generalized, 6 segmental; mean (range) age at implantation, 37.0 (8-67) years; mean follow-up duration after implantation, 10.9 (9-13) years. We employed the Unified Dystonia Rating Scale for motor and Short Form Health Survey for HRQoL assessments to monitor the change longitudinally. We analyzed the changes in motor and HRQoL at 1-2 years (short-term) and ≥9 years (long-term) follow-up as compared to baseline with a Wilcoxon signed-rank test. We assessed the factors that predicted motor and HRQoL improvement with univariate regression analyses.

RESULTS

Motor (41.6%; p = 0.004) and HRQoL (total score, p = 0.039) improvements remained significant at long-term follow-up and, in the regression analysis, change in HRQoL outcomes correlated significantly with change in motor outcomes (R² = 0.384, p = 0.010). Additionally, short-term motor and HRQoL improvements predicted the long-term motor (R² = 0.384, p = 0.010) and HRQoL (total score, R² = 0.594, p < 0.001) outcomes, respectively.

CONCLUSION

Motor and HRQoL improvements with DBS in isolated dystonia remain sustained for nearly a decade and may largely be predictable by the short-term response to DBS.

Implementation of the Current Dystonia Classification from 2013 to 2018

Background

There is a discrepancy in the way dystonia is classified in the literature, as articles continue to reference the old criteria or fail to use the 2013 criteria correctly.

Methods

We performed a systematic review of the dystonia literature and distinguished between studies that use the new classification correctly, made errors in implementing the new classification, or continued to use the old classification methods.

Results

Of the 990 articles included in the study, 59.8% used the classification correctly, 31.3% used mixed terminology, and 8.9% continued to use the old classification. Articles relating to surgery were significantly less likely to use the new classification correctly. There is an upward trend in the annual rate of articles properly referencing the new classification.

Conclusions

The 2013 classification has been well received in scientific literature, and more studies are adapting to its use.