Surgical Treatment of Parkinson Disease

Surgery in Parkinson disease is effective for a select group of patients when optimal medical management is not sufficient. Functional neurosurgery can be used as either a salvage therapy in patients with disabling symptoms or to maintain quality of life and independence before progression to severe disability in high-functioning patients. With recent technological advancements in imaging and targeting as well as novel neuromodulation paradigms, there are numerous options for targeted brain lesions and deep brain stimulation. Surgical decision making and postoperative management in Parkinson disease therefore often requires a multidisciplinary team effort with neurology, neurosurgery, neuropsychology, and psychiatry.

Cerebellar Deep Brain Stimulation for Acquired Hemidystonia

Background

The cerebellum's role in dystonia is increasingly recognized. Dystonia can be a disabling and refractory condition; deep brain stimulation can help many patients, but it is traditionally less effective in acquired dystonia. New surgical targets would be instrumental in providing treatment options and understanding dystonia further.

Objective

To evaluate the efficacy of deep brain stimulation of the cerebellum in acquired dystonia.

Methods

We report our management of a 37-year-old woman with severe left arm and leg dystonia, a complication of an ischemic stroke in childhood. She had already had 2 thalamotomies with only transient benefit. These procedures, in addition to her initial stroke that had damaged the basal ganglia, left traditional deep brain stimulation targets unavailable.

Results

After implantation of bilateral deep cerebellar nuclei, dystonia improved with a 40% reduction in severity on scales and subjective reports of improved posturing, gait, and pain. This improvement has been maintained for almost 2 years after implantation.

Conclusion

Cerebellar stimulation has potential for therapeutic benefit in acquired dystonia and should be further explored.

Image-based analysis and long-term clinical outcomes of deep brain stimulation for Tourette syndrome: a multisite study

BACKGROUND

Deep brain stimulation (DBS) can be an effective therapy for tics and comorbidities in select cases of severe, treatment-refractory Tourette syndrome (TS). Clinical responses remain variable across patients, which may be attributed to differences in the location of the neuroanatomical regions being stimulated. We evaluated active contact locations and regions of stimulation across a large cohort of patients with TS in an effort to guide future targeting.

METHODS

We collected retrospective clinical data and imaging from 13 international sites on 123 patients. We assessed the effects of DBS over time in 110 patients who were implanted in the centromedial (CM) thalamus (n=51), globus pallidus internus (GPi) (n=47), nucleus accumbens/anterior limb of the internal capsule (n=4) or a combination of targets (n=8). Contact locations (n=70 patients) and volumes of tissue activated (n=63 patients) were coregistered to create probabilistic stimulation atlases.

RESULTS

Tics and obsessive-compulsive behaviour (OCB) significantly improved over time (p<0.01), and there were no significant differences across brain targets (p>0.05). The median time was 13 months to reach a 40% improvement in tics, and there were no significant differences across targets (p=0.84), presence of OCB (p=0.09) or age at implantation (p=0.08). Active contacts were generally clustered near the target nuclei, with some variability that may reflect differences in targeting protocols, lead models and contact configurations. There were regions within and surrounding GPi and CM thalamus that improved tics for some patients but were ineffective for others. Regions within, superior or medial to GPi were associated with a greater improvement in OCB than regions inferior to GPi.

CONCLUSION

The results collectively indicate that DBS may improve tics and OCB, the effects may develop over several months, and stimulation locations relative to structural anatomy alone may not predict response. This study was the first to visualise and evaluate the regions of stimulation across a large cohort of patients with TS to generate new hypotheses about potential targets for improving tics and comorbidities.

Globus Pallidus Interna or Subthalamic Nucleus Deep Brain Stimulation for Parkinson Disease: A Review

Importance

Selection of the best deep brain stimulation (DBS) target-subthalamic nucleus (STN) or globus pallidus interna (GPi)-for treatment of motor complications in Parkinson disease remains a matter of debate.

Observations

Increasing evidence from randomized clinical trials indicates that motor benefit is similar between both targets, including an effect on dyskinesia and improvement in quality of life. Deep brain stimulation of the STN offers consistently greater dopaminergic medication reduction, possible mild benefit in nonmotor domains, and potential economic advantage. Deep brain stimulation of the GPi provides a probable advantage in dyskinesia suppression, management of symptoms with unilateral leads, and flexibility in medications and programming adjustments. Overall, STN DBS is at potentially higher or equal risk for neuropsychiatric changes compared with GPi DBS.

Conclusions and Relevance

Both GPi and STN DBS provide similar, consistent, marked motor benefits, but subtle target differences exist. Target selection should be tailored to each patient's clinical presentation, neuropsychiatric profile, and goals of surgery, allowing customization of this therapy and improved individual outcomes.

Washout of chronic therapeutic deep brain stimulation increases cortical phase-amplitude coupling

Invasive human brain recordings have shown that acute therapeutic deep brain stimulation (DBS) reduces cortical synchronization, measured by coupling of beta phase to gamma amplitude. Here we show by noninvasive scalp electroencephalography that withdrawal of chronic DBS elevates phase-amplitude coupling, in proportion to the worsening of contralateral rigidity.

Patient Experience with Rechargeable Implantable Pulse Generator Deep Brain Stimulation for Movement Disorders

BACKGROUND/AIMS

Nonrechargeable deep brain stimulation implantable pulse generators (IPGs) for movement disorders require surgical replacement every few years due to battery depletion. Rechargeable IPGs reduce frequency of replacement surgeries and inherent risks of complications but require frequent recharging. Here, we evaluate patient experience with rechargeable IPGs and define predictive characteristics for higher satisfaction.

METHODS

We contacted all patients implanted with rechargeable IPGs at a single center in a survey-based study. We analyzed patient satisfaction with respect to age, diagnosis, target, charging duration, and body mass index. We tabulated hardware-related adverse events.

RESULTS

Dystonia patients had significantly higher satisfaction than Parkinson's disease patients in recharging, display, programmer, and training domains. Common positive responses were "fewer surgeries" and "small size." Common negative responses were "difficulty finding the right position to recharge" and "need to recharge every day." Hardware-related adverse events occurred in 21 of 59 participants.

CONCLUSION

Patient experience with rechargeable IPGs was largely positive; however, frustrations with recharging and adverse events were common. Dystonia diagnosis was most predictive of high satisfaction across multiple categories, potentially related to expected long disease duration with need for numerous IPG replacements.

Telepsychiatry for patients with movement disorders: a feasibility and patient satisfaction study

Background

Telemedicine is a convenient health service delivery modality for patients with movement disorders, including Parkinson's disease (PD), but is currently underutilized in the management of associated psychiatric symptoms. This study explored the feasibility of and patient satisfaction with telepsychiatry services at an academic movement disorders center.

Methods

All patients seen by telepsychiatry between January and December 2017 at the UCSF Movement Disorders and Neuromodulation Center were invited to participate. Participation was voluntary. Patients received an initial survey after the first telepsychiatry visit and satisfaction surveys after each visit. Survey responses were collected online via Research Electronic Data Capture (REDCap). Frequencies were calculated for categorical variables, and means and standard deviations were generated for continuous variables.

Results

Thirty-three patients (79% with PD; 72% Medicare recipients; 64% men; mean age, 61.1 ± 10.5 years; mean distance to clinic, 79.9 ± 81.3 miles) completed a total of 119 telepsychiatry and 62 in-person visits. Twenty-two initial surveys and 50 satisfaction surveys (from 21 patients) were collected. Patients were very satisfied with the care (95%), convenience (100%), comfort (95%), and overall visit (95%). Technical quality was somewhat lower rated, with 76% patients reporting they were very satisfied, while 19% were satisfied. All patients would recommend telemedicine to friends or family members.

Conclusions

Telepsychiatry is a feasible option for patients with movement disorders, leading to high patient satisfaction and improved access to care. Technical aspects still need optimization. Whenever available, telepsychiatry can be considered in addition to in-person visits. Future studies with larger samples should explore its impact on patient care outcomes and caregiver burden.

Effect of levodopa on electroencephalographic biomarkers of the parkinsonian state

The objective of this study was to evaluate proposed electroencephalographic (EEG) biomarkers of Parkinson's disease (PD) and test their correlation with motor impairment in a new, well-characterized cohort of PD patients and controls. Sixty-four-channel EEG was recorded from 14 patients with rigid-akinetic PD with minimal tremor and from 14 age-matched healthy controls at rest and during voluntary movement. Patients were tested off and on medication during a single session. Recordings were analyzed for phase-amplitude coupling over sensorimotor cortex and for pairwise coherence from all electrode pairs in the recording montage (distributed coherence). Phase-amplitude coupling and distributed coherence were found to be elevated Off compared with On levodopa, and their reduction was correlated with motor improvement. In the Off medication state, phase-amplitude coupling was greater in sensorimotor contacts contralateral to the most affected body part and reduced by voluntary movement. We conclude that phase-amplitude coupling and distributed coherence are cortical biomarkers of the parkinsonian state that are detectable noninvasively and may be useful as objective aids for management of dopaminergic therapy. Several analytic methods may be used for noninvasive measurement of abnormal brain synchronization in PD. Calculation of phase-amplitude coupling requires only a single electrode over motor cortex. NEW & NOTEWORTHY Several EEG biomarkers of the parkinsonian state have been proposed that are related to abnormal cortical synchronization. We report several new findings in this study: correlations of EEG markers of synchronization with specific motor signs of Parkinson's disease (PD), and demonstration that one of the EEG markers, phase-amplitude coupling, is more elevated over the more clinically affected brain hemisphere. These findings underscore the potential utility of scalp EEG for objective, noninvasive monitoring of medication state in PD.

Pallidal thermolesion unleashes gamma oscillations in the motor cortex in Parkinson's disease

BACKGROUND

In Parkinson's disease, the emergence of motor dysfunction is thought to be related to an imbalance between "antikinetic" and "prokinetic" patterns of oscillatory activity in the motor network. Invasive recordings from the basal ganglia and cortex in surgical patients have suggested that levodopa and therapeutic deep brain stimulation can suppress antikinetic beta band (13-30 Hz) rhythms while promoting prokinetic gamma band (60-90 Hz) rhythms. Surgical ablation of the globus pallidus internus is one of the oldest effective therapies for Parkinson's disease and produces remarkably immediate relief of rigidity and bradykinesia, but its effects on oscillatory activity in the motor network have not been studied.

OBJECTIVES

We characterize the effects of pallidotomy on cortical oscillatory activity in Parkinson's patients.

METHODS

Using a temporary 6-contact lead placed over the sensorimotor cortex in the subdural space, we recorded acute changes in cortical oscillatory activities in 3 Parkinson's disease patients undergoing pallidotomy and compared the results to that of 3 essential tremor patients undergoing thalamotomy.

RESULTS

In all 3 Parkinson's disease patients, we observed the emergence of a ~70-80 Hz narrowband oscillation with effective thermolesion of the pallidum. This gamma oscillatory activity was spatially localized over the primary motor cortex, was minimally affected by voluntary movements, and was not found in the motor cortex of essential tremor patients undergoing thalamotomy.

CONCLUSIONS

Our finding suggests that acute lesioning of the pallidum promotes cortical gamma band oscillations. This may represent an important mechanism for alleviating bradykinesia in Parkinson's disease. © 2019 International Parkinson and Movement Disorder Society.

Physiological effects of subthalamic nucleus deep brain stimulation surgery in cervical dystonia

BACKGROUND

Subthalamic nucleus deep brain stimulation (STN DBS) surgery is clinically effective for treatment of cervical dystonia; however, the underlying physiology has not been examined. We used transcranial magnetic stimulation (TMS) to examine the effects of STN DBS on sensorimotor integration, sensorimotor plasticity and motor cortex excitability, which are identified as the key pathophysiological features underlying dystonia.

METHODS

TMS paradigms of short latency afferent inhibition (SAI) and long latency afferent inhibition (LAI) were used to examine the sensorimotor integration. Sensorimotor plasticity was measured with paired associative stimulation paradigm, and motor cortex excitability was examined with short interval intracortical inhibition and intracortical facilitation. DBS was turned off and on to record these measures.

RESULTS

STN DBS modulated SAI and LAI, which correlated well with the acute clinical improvement. While there were no changes seen in the motor cortex excitability, DBS was found to normalise the sensorimotor plasticity; however, there was no clinical correlation.

CONCLUSION

Modulation of sensorimotor integration is a key contributor to clinical improvement with acute stimulation of STN. Since the motor cortex excitability did not change and the change in sensorimotor plasticity did not correlate with clinical improvement, STN DBS demonstrates restricted effects on the underlying physiology.

CLINICAL TRIAL REGISTRATION

NCT01671527.

Adaptive deep brain stimulation for Parkinson's disease using motor cortex sensing

OBJECTIVE

Contemporary deep brain stimulation (DBS) for Parkinson's disease is delivered continuously, and adjustments based on patient's changing symptoms must be made manually by a trained clinician. Patients may be subjected to energy intensive settings at times when they are not needed, possibly resulting in stimulation-induced adverse effects, such as dyskinesia. One solution is 'adaptive' DBS, in which stimulation is modified in real time based on neural signals that co-vary with the severity of motor signs or of stimulation-induced adverse effects. Here we show the feasibility of adaptive DBS using a fully implanted neural prosthesis.

APPROACH

We demonstrate adaptive deep brain stimulation in two patients with Parkinson's disease using a fully implanted neural prosthesis that is enabled to utilize brain sensing to control stimulation amplitude (Activa PC  +  S). We used a cortical narrowband gamma (60-90 Hz) oscillation related to dyskinesia to decrease stimulation voltage when gamma oscillatory activity is high (indicating dyskinesia) and increase stimulation voltage when it is low.

MAIN RESULTS

We demonstrate the feasibility of 'adaptive deep brain stimulation' in two patients with Parkinson's disease. In short term in-clinic testing, energy savings were substantial (38%-45%), and therapeutic efficacy was maintained.

SIGNIFICANCE

This is the first demonstration of adaptive DBS in Parkinson's disease using a fully implanted device and neural sensing. Our approach is distinct from other strategies utilizing basal ganglia signals for feedback control.

Effects of deep brain stimulation on rest tremor progression in early stage Parkinson disease

OBJECTIVE

To evaluate whether the progression of individual motor features was influenced by early deep brain stimulation (DBS), a post hoc analysis of Unified Parkinson's Disease Rating Scale-III (UPDRS-III) score (after a 7-day washout) was conducted from the 2-year DBS in early Parkinson disease (PD) pilot trial dataset.

METHODS

The prospective pilot trial enrolled patients with PD aged 50-75 years, treated with PD medications for 6 months-4 years, and no history of dyskinesia or other motor fluctuations, who were randomized to receive optimal drug therapy (ODT) or DBS plus ODT (DBS + ODT). At baseline and 6, 12, 18, and 24 months, all patients stopped all PD therapy for 1 week (medication and stimulation, if applicable). UPDRS-III "off" item scores were compared between the ODT and DBS + ODT groups (n = 28); items with significant between-group differences were analyzed further.

RESULTS

UPDRS-III "off" rest tremor score change from baseline to 24 months was worse in patients receiving ODT vs DBS + ODT (p = 0.002). Rest tremor slopes from baseline to 24 months favored DBS + ODT both "off" and "on" therapy (p < 0.001, p = 0.003, respectively). More ODT patients developed new rest tremor in previously unaffected limbs than those receiving DBS + ODT (p = 0.001).

CONCLUSIONS

These results suggest the possibility that DBS in early PD may slow rest tremor progression. Future investigation in a larger cohort is needed, and these findings will be tested in the Food and Drug Administration-approved, phase III, pivotal, multicenter clinical trial evaluating DBS in early PD.

CLASSIFICATION OF EVIDENCE

This study provides Class II evidence that for patients with early PD, DBS may slow the progression of rest tremor.

Automated Deep Brain Stimulation Programming for Tremor

Deep brain stimulation (DBS) programming, the systematic selection of fixed electrical stimulation parameters that deliver maximal therapeutic benefit while limiting side effects, poses several challenges in the treatment of movement disorders. DBS programming requires the expertise of trained neurologists or nurses who assess patient symptoms according to standardized clinical rating scales and use patient reports of DBS-related side effects to adjust stimulation parameters and optimize therapy. In this paper, we describe and validate an automated software platform for DBS programming for tremor associated with Parkinson's disease and essential tremor. DBS parameters are changed automatically through a direct computer interface with implanted neurostimulators. Each tested DBS setting is ranked according to its effect on tremor, which is assessed using smartwatch inertial measurement unit data, and side effects, which are reported through a user interface. Blinded neurologist assessments showed the automated programming method performed at least as well as clinician mediated programming in selecting the optimal settings for tremor therapy. This proof of concept study describes a novel DBS programming paradigm that may improve programming efficiency and outcomes, increase access to programming outside specialty clinics, and aid in the development of adaptive and closed-loop DBS strategies.

Cortical gamma oscillations in isolated dystonia

We describe a novel electrophysiologic signal from the motor cortex of patients with generalized dystonia - a discrete gamma-band oscillation induced by movement and associated with emergence of dystonia. This was observed using both invasive and non-invasive methods. This phenomenon is similar to the gamma oscillation reported in parkinsonian dyskinesia.

Chronic deep brain stimulation normalizes scalp EEG activity in isolated dystonia

OBJECTIVE

To investigate cortical activity using scalp EEG in patients with isolated dystonia treated with chronic deep brain stimulation (DBS), on and off stimulation.

METHODS

We analyzed 64-channel scalp EEG in 12 isolated dystonia patients treated with chronic DBS (7 generalized, 5 cervical/segmental; 7 globus pallidus (GP), 5 subthalamic nucleus (STN)), and 20 healthy age-matched controls. Recordings during rest and movement task, and clinical motor scores, were collected with DBS-on and during a 90-min DBS washout.

RESULTS

Resting state alpha power in the dominant (or contralateral to more dystonic side) motor cortex channel during DBS was comparable to healthy controls, but it increased when DBS was stopped. Resting state and movement-related alpha coherence between bilateral motor cortex channels was increased off DBS.

CONCLUSIONS

Chronic DBS reduces exaggerated alpha oscillations and interhemispheric alpha coherence in the motor cortex of patients with isolated dystonia.

SIGNIFICANCE

These findings complement related studies in Parkinson's disease and support the view that network desynchronization is a prominent mechanism of DBS in movement disorders.

Clinical Tremor Severity Estimation Using an Instrumented Eating Utensil

We demonstrate the feasibility of estimating clinical tremor scores using an eating utensil with motion-sensing and tremor-cancellation technology in thirteen patients with tremor. Three experts scored hand tremor using the modified Fahn- Tolosa-Marin (FTM) scale. A linear model was trained to estimate tremor severity using the recorded motion signals. The average neurologist FTM score was 1.6±0.7 for PD and 2.6±0.7 for ET patients. The average model score was 1.6±0.7 for PD and 2.6±0.6 for ET. Correlation coefficient between the clinical and model tremor scores was 0.91 (p < 0.001). Motion data from an instrumented eating utensil accurately derived tremor ratings enabling practical, objective daily monitoring.

Intractable Blepharospasm Treated with Bilateral Pallidal Deep Brain Stimulation

BACKGROUND

Blepharospasm can be present as an isolated dystonia or in conjunction with other forms of cranial dystonia, causing significant disability.

CASE REPORT

We report a case of a 69-year-old male with craniocervical dystonia, manifesting primarily as incapacitating blepharospasm refractory to medical treatments. He underwent bilateral globus pallidus (GP) deep brain stimulation (DBS) with complete resolution of his blepharospasm and sustained benefit at 12 months postoperatively.

DISCUSSION

This case illustrates successful treatment of blepharospasm with pallidal stimulation. GP-DBS should be considered a reasonable therapeutic option for intractable blepharospasm.

Chronic multisite brain recordings from a totally implantable bidirectional neural interface: experience in 5 patients with Parkinson's disease

OBJECTIVE Dysfunction of distributed neural networks underlies many brain disorders. The development of neuromodulation therapies depends on a better understanding of these networks. Invasive human brain recordings have a favorable temporal and spatial resolution for the analysis of network phenomena but have generally been limited to acute intraoperative recording or short-term recording through temporarily externalized leads. Here, the authors describe their initial experience with an investigational, first-generation, totally implantable, bidirectional neural interface that allows both continuous therapeutic stimulation and recording of field potentials at multiple sites in a neural network. METHODS Under a physician-sponsored US Food and Drug Administration investigational device exemption, 5 patients with Parkinson's disease were implanted with the Activa PC+S system (Medtronic Inc.). The device was attached to a quadripolar lead placed in the subdural space over motor cortex, for electrocorticography potential recordings, and to a quadripolar lead in the subthalamic nucleus (STN), for both therapeutic stimulation and recording of local field potentials. Recordings from the brain of each patient were performed at multiple time points over a 1-year period. RESULTS There were no serious surgical complications or interruptions in deep brain stimulation therapy. Signals in both the cortex and the STN were relatively stable over time, despite a gradual increase in electrode impedance. Canonical movement-related changes in specific frequency bands in the motor cortex were identified in most but not all recordings. CONCLUSIONS The acquisition of chronic multisite field potentials in humans is feasible. The device performance characteristics described here may inform the design of the next generation of totally implantable neural interfaces. This research tool provides a platform for translating discoveries in brain network dynamics to improved neurostimulation paradigms. Clinical trial registration no.: NCT01934296 (clinicaltrials.gov).

Thalamic DBS with a constant-current device in essential tremor: A controlled clinical trial

INTRODUCTION

This study of thalamic deep brain stimulation (DBS) investigated whether a novel constant-current device improves tremor and activities of daily living (ADL) in patients with essential tremor (ET).

METHODS

A prospective, controlled, multicenter study was conducted at 12 academic centers. We investigated the safety and efficacy of unilateral and bilateral constant-current DBS of the ventralis intermedius (VIM) nucleus of the thalamus in patients with essential tremor whose tremor was inadequately controlled by medications. The primary outcome measure was a rater-blinded assessment of the change in the target limb tremor score in the stimulation-on versus stimulation-off state six months following surgery. Multiple secondary outcomes were assessed at one-year follow-up, including motor, mood, and quality-of-life measures.

RESULTS

127 patients were implanted with VIM DBS. The blinded, primary outcome variable (n = 76) revealed a mean improvement of 1.25 ± 1.26 points in the target limb tremor rating scale (TRS) score in the arm contralateral to DBS (p < 0.001). Secondary outcome variables at one year revealed significant improvements (p ≤ 0.001) in quality of life, depression symptoms, and ADL scores. Forty-seven patients had a second contralateral VIM-DBS, and this group demonstrated reduction in second-sided tremor at 180 days (p < 0.001). Serious adverse events related to the surgery included infection (n = 3), intracranial hemorrhage (n = 3), and device explantation (n = 3).

CONCLUSION

Unilateral and bilateral constant-current VIM DBS significantly improves upper extremity tremor, ADL, quality of life, and depression in patients with severe ET.

Deep brain stimulator implantation in a diagnostic MRI suite: infection history over a 10-year period

OBJECTIVE

The objective of this study was to assess the incidence of postoperative hardware infection following interventional (i)MRI–guided implantation of deep brain stimulation (DBS) electrodes in a diagnostic MRI scanner.

METHODS

A diagnostic 1.5-T MRI scanner was used over a 10-year period to implant DBS electrodes for movement disorders. The MRI suite did not meet operating room standards with respect to airflow and air filtration but was prepared and used with conventional sterile procedures by an experienced surgical team. Deep brain stimulation leads were implanted while the patient was in the magnet, and patients returned 1–3 weeks later to undergo placement of the implantable pulse generator (IPG) and extender wire in a conventional operating room. Surgical site infections requiring the removal of part or all of the DBS system within 6 months of implantation were scored as postoperative hardware infections in a prospective database.

RESULTS

During the 10-year study period, the authors performed 164 iMRI-guided surgical procedures in which 272 electrodes were implanted. Patients ranged in age from 7 to 78 years, and an overall infection rate of 3.6% was found. Bacterial cultures indicated Staphylococcus epidermis (3 cases), methicillin-susceptible Staphylococcus aureus (2 cases), or Propionibacterium sp. (1 case). A change in sterile practice occurred after the first 10 patients, leading to a reduction in the infection rate to 2.6% (4 cases in 154 procedures) over the remainder of the procedures. Of the 4 infections in this patient subset, all occurred at the IPG site.

CONCLUSIONS

Interventional MRI–guided DBS implantation can be performed in a diagnostic MRI suite with an infection risk comparable to that reported for traditional surgical placement techniques provided that sterile procedures, similar to those used in a regular operating room, are practiced.

Subthalamic nucleus deep brain stimulation in isolated dystonia: A 3-year follow-up study

OBJECTIVE

To report long-term safety and efficacy outcomes of a large cohort of patients with medically refractory isolated dystonia treated with subthalamic nucleus (STN) deep brain stimulation (DBS).

METHODS

Twenty patients (12 male, 8 female; mean age 49 ± 16.3 years) with medically refractory isolated dystonia were studied (14 were followed for 36 months). The primary endpoints were change in Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) motor score and Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) total score at 36 months compared to preoperative baseline. Multiple secondary outcomes were also assessed (ClinicalTrials.gov NCT00773604).

RESULTS

Eighteen of 20 patients showed improvement 12 months after STN DBS with sustained benefit persisting for 3 years (n = 14). At 36 months, BFMDRS motor scores improved 70.4% from a mean 17.9 ± 8.5 to 5.3 ± 5.6 (p = 0.0002) and total TWSTRS scores improved 66.6% from a mean 41.0 ± 18.9 to 13.7 ± 17.9 (p = 0.0002). Improvement at 36 months was equivalent to that seen at 6 months. Disability and quality of life measures were also improved. Three hardware-related and 24 stimulation-related nonserious adverse events occurred between years 1 and 3 (including 4 patients with dyskinesia).

CONCLUSIONS

This study offers support for long-term tolerability and sustained effectiveness of STN DBS in the treatment of severe forms of isolated dystonia.

CLASSIFICATION OF EVIDENCE

This study provides Class IV evidence that STN DBS decreases long-term dystonia severity in patients with medically refractory isolated dystonia.

Proceedings of the Fourth Annual Deep Brain Stimulation Think Tank: A Review of Emerging Issues and Technologies

This paper provides an overview of current progress in the technological advances and the use of deep brain stimulation (DBS) to treat neurological and neuropsychiatric disorders, as presented by participants of the Fourth Annual DBS Think Tank, which was convened in March 2016 in conjunction with the Center for Movement Disorders and Neurorestoration at the University of Florida, Gainesveille FL, USA. The Think Tank discussions first focused on policy and advocacy in DBS research and clinical practice, formation of registries, and issues involving the use of DBS in the treatment of Tourette Syndrome. Next, advances in the use of neuroimaging and electrochemical markers to enhance DBS specificity were addressed. Updates on ongoing use and developments of DBS for the treatment of Parkinson's disease, essential tremor, Alzheimer's disease, depression, post-traumatic stress disorder, obesity, addiction were presented, and progress toward innovation(s) in closed-loop applications were discussed. Each section of these proceedings provides updates and highlights of new information as presented at this year's international Think Tank, with a view toward current and near future advancement of the field.