Pallidal deep brain stimulation in patients with cervical dystonia and severe cervical dyskinesias with cervical myelopathy

Os odontoideum and craniovertebral junction instability secondary to dystonia: case series and review of the literature

INTRODUCTION

Os odontoideum refers to a rounded ossicle detached from a hypoplastic odontoid process at the body of the axis. The aetiology has been debated and believed to be either congenital or acquired (resulting from trauma). Os odontoideum results in incompetence of the transverse ligament and thus predisposes to atlantoaxial instability and spinal cord injury.

METHODS/RESULTS

Three cases of children with severe dystonic cerebral palsy presenting with myelopathic deterioration secondary to atlantoaxial instability due to os odontoideum are presented. This observation supports the hypothesis of os odontoideum being an acquired phenomenon, secondary to chronic excessive movement with damage to the developing odontoid process.

CONCLUSION

In children with cerebral palsy and dystonia, pre-existing motor deficits may conceal an evolving myelopathy and result in delayed diagnosis of clinically significant atlantoaxial subluxation.

Multipoint fixation with vascularised fibular bone graft and myotomy for atlanto-axial instability in cervical dystonia: a case report

Spinal instability is a challenging condition to manage in patients with cervical dystonia. Standard surgical stabilisation approaches may fail to cope with additional stress forces created by spasmodic muscles leading to construct failure either in the immediate or late post-operative period. Long-term stabilisation relies on the management of dystonic symptoms and adjunctive strategies to increase fusion success rate. We discuss the management of a challenging patient with translational C1/2 instability who had three metalwork failures with standard occipito-cervical fixation techniques within a 12 month period. A combined surgical approach using multipoint fixation, sternocleidomastoid myotomy and a vascularised fibular occiput-C2 bone graft successfully prevented further metalwork failure at over 2 years follow up.

Deep Brain Stimulation Before Anterior Cervical Discectomy and Fusion for a Patient With Cervical Dystonia and Cervical Myelopathy: A Case Report

Cervical dystonia with concurrent cervical myelopathy is a challenging pathology that requires thoughtful management. A 46-year-old female was referred to our center with this presentation. We elected to perform bilateral globus pallidus internus deep brain stimulation (DBS-GPi) prior to C5 to C7 anterior cervical discectomy and fusion (ACDF) to avoid the potential for dystonic movements to negatively impact cervical fusion. The patient was followed up at three months post C5 to C7 ACDF and nine months post DBS-GPi with complete control of tremor and no radiographic evidence of hardware loosening or malalignment. Though this strategy was successful in treating both our patient's cervical myelopathy and cervical dystonia, larger studies need to be conducted to optimize the treatment of patients presenting with these concurrent pathologies.

Are Transventricular Approaches Associated With Increased Hemorrhage? A Comparative Study in a Series of 624 Deep Brain Stimulation Surgeries

BACKGROUND

Deep brain stimulation (DBS) surgery has advanced tremendously, for both clinical applications and technology. Although DBS surgery is an overall safe procedure, rare side effects, in particular, hemorrhage, may result in devastating consequences. Although there are certain advantages with transventricular trajectories, it has been reasoned that avoidance of such trajectories would likely reduce hemorrhage.

OBJECTIVE

To investigate the possible impact of a transventricular trajectory as compared with a transcerebral approach on the occurrence of symptomatic and asymptomatic hemorrhage after DBS electrode placement.

METHODS

Retrospective evaluation of 624 DBS surgeries in 582 patients, who underwent DBS surgery for movement disorders, chronic pain, or psychiatric disorders. A stereotactic guiding cannula was routinely used for DBS electrode insertion. All patients had postoperative computed tomography scans within 24 hours after surgery.

RESULTS

Transventricular transgression was identified in 404/624 DBS surgeries. The frequency of hemorrhage was slightly higher in transventricular than in transcerebral DBS surgeries (15/404, 3.7% vs 6/220, 2.7%). While 7/15 patients in the transventricular DBS surgery group had a hemorrhage located in the ventricle, 6 had an intracerebral hemorrhage along the electrode trajectory unrelated to transgression of the ventricle and 2 had a subdural hematoma. Among the 7 patients with a hemorrhage located in the ventricle, only one became symptomatic. Overall, a total of 7/404 patients in the transventricular DBS surgery group had a symptomatic hemorrhage, whereas the hemorrhage remained asymptomatic in all 6/220 patients in the transcerebral DBS surgery group.

CONCLUSION

Transventricular approaches in DBS surgery can be performed safely, in general, when special precautions such as using a guiding cannula are routinely applied.

Deep Brain Stimulation in childhood-onset dystonia due to brain pathology. A long-term study

BACKGROUND

Pallidal Deep Brain Stimulation (DBS) is an established treatment option for isolated, inherited or idiopathic dystonia, however data on its safety and efficacy in other forms of dystonia are more limited.

OBJECTIVES

Retrospective analysis of motor and non-motor outcomes in pediatric onset refractory dystonia due to static or progressive brain disorders in a cohort of patients with a DBS treatment duration ≥12 months.

METHODS

Multidisciplinary assessments including standardised scales/tests of motor function, pain, quality of life, cognition and language were carried out before implantation and longitudinally afterwards.

RESULTS

9 patients were included, 7 had cerebral palsy. Mean age at implantation was 209 months ± 156, mean treatment duration 84 ± 37 months. DBS was well tolerated and positively affected both motor and non-motor functions. In particular, statistically significant improvements were documented in Burke-Fahn-Marsden Scale scores (- 19.9% p 0.01031) at 12 months and in long-term quality of life (+28.6%, p 0.0292).

CONCLUSIONS

DBS may be a useful treatment option in generalized dystonia associated with brain pathology. Even when the motor benefits are limited, improvements in quality of life and non-motor functions, or the possible prevention of serious dystonia-related complications, may have a significant impact on overall clinical status.

One Hundred Top Cited Articles in Cervical Myelopathy: A Bibliographic Analysis

STUDY DESIGN

A bibliometric review of the literature.

OBJECTIVES

The aim of this study was to identify the most highly cited articles relating to cervical myelopathy and to analyze the most influential articles.

SUMMARY OF BACKGROUND DATA

Over the past several decades, a lot of research has been conducted regarding the subject of cervical myelopathy. Although there are a large number of articles on this topic, to our knowledge, this is the first bibliometric analysis.

METHODS

A selection of search terms and keywords were inputted into the "Dimensions" database and the most highly cited articles in cervical myelopathy were selected from high impact factor journals. The top 100 articles were analyzed for year of publication, authorship, publishing journals, institution and country of origin, subject matter, article type, and level of evidence.

RESULTS

The 100 most cited articles in the topic of cervical myelopathy were published from 1956 to 2015. These articles, their corresponding authors, and number of citations are shown in Table 1. The number of citations ranged from 121 times for the 100th article to 541 times for the top article in a total of 20 journals. The most common topic was operative technique, whereas the journals which contributed the most articles were the Spine journal and the Journal of Neurosurgery.

CONCLUSION

Our study provided an extensive list of the most historically significant articles regarding cervical myelopathy, acknowledging the key contributions made to the advancement of this field.Level of Evidence: 5.

Deep brain stimulation of the brainstem

Deep brain stimulation (DBS) of the subthalamic nucleus, pallidum, and thalamus is an established therapy for various movement disorders. Limbic targets have also been increasingly explored for their application to neuropsychiatric and cognitive disorders. The brainstem constitutes another DBS substrate, although the existing literature on the indications for and the effects of brainstem stimulation remains comparatively sparse. The objective of this review was to provide a comprehensive overview of the pertinent anatomy, indications, and reported stimulation-induced acute and long-term effects of existing white and grey matter brainstem DBS targets. We systematically searched the published literature, reviewing clinical trial articles pertaining to DBS brainstem targets. Overall, 164 studies describing brainstem DBS were identified. These studies encompassed 10 discrete structures: periaqueductal/periventricular grey (n = 63), pedunculopontine nucleus (n = 48), ventral tegmental area (n = 22), substantia nigra (n = 9), mesencephalic reticular formation (n = 7), medial forebrain bundle (n = 8), superior cerebellar peduncles (n = 3), red nucleus (n = 3), parabrachial complex (n = 2), and locus coeruleus (n = 1). Indications for brainstem DBS varied widely and included central neuropathic pain, axial symptoms of movement disorders, headache, depression, and vegetative state. The most promising results for brainstem DBS have come from targeting the pedunculopontine nucleus for relief of axial motor deficits, periaqueductal/periventricular grey for the management of central neuropathic pain, and ventral tegmental area for treatment of cluster headaches. Brainstem DBS has also acutely elicited numerous motor, limbic, and autonomic effects. Further work involving larger, controlled trials is necessary to better establish the therapeutic potential of DBS in this complex area.

Edge-enhancing gradient echo with multi-image co-registration and averaging (EDGE-MICRA) for targeting thalamic centromedian and parafascicular nuclei

BACKGROUND AND PURPOSE

Deep brain stimulation of the thalamus is an effective treatment for multiple neurological disorders. The centromedian and parafascicular nuclei are recently emerging targets for multiple conditions, such as epilepsy and Tourette syndrome; however, their limited visibility on conventional magnetic resonance imaging sequences has been a major obstacle. The goal of this study was to demonstrate the feasibility of a high-resolution and high-contrast targeting sequence for centromedian-parafascicular deep brain stimulation using a recently described magnetic resonance imaging sequence, three-dimensional edge-enhancing gradient echo.

METHODS

The three-dimensional edge-enhancing gradient echo sequence was performed on a normal volunteer for a total of six acquisitions. Multi-image co-registration and averaging was performed by first co-registering each of the six scans and then averaging to produce an edge-enhancing gradient echo-multi-image co-registration and averaging scan. The averaging was also performed for two, three, four and five scans to assess the change in the signal-to-noise ratio and identify the ideal balance of image quality and scan time.

RESULTS

The edge-enhancing gradient echo-multi-image co-registration and averaging scan allowed clear boundary delineation of the centromedian and parafascicular nuclei. The signal-to-noise ratio increased as a function of increasing scan number, but the added gain was small beyond four scans for the imaging parameters used in this study.

CONCLUSIONS

The recently described three-dimensional edge-enhancing gradient echo sequence provides an easily implementable approach, using widely available magnetic resonance imaging technology without complex post-processing techniques, to delineate centromedian and parafascicular nuclei for deep brain stimulation targeting.

Divergent pallidal pathways underlying distinct Parkinsonian behavioral deficits

The basal ganglia regulate a wide range of behaviors, including motor control and cognitive functions, and are profoundly affected in Parkinson's disease (PD). However, the functional organization of different basal ganglia nuclei has not been fully elucidated at the circuit level. In this study, we investigated the functional roles of distinct parvalbumin-expressing neuronal populations in the external globus pallidus (GPe-PV) and their contributions to different PD-related behaviors. We demonstrate that substantia nigra pars reticulata (SNr)-projecting GPe-PV neurons and parafascicular thalamus (PF)-projecting GPe-PV neurons are associated with locomotion and reversal learning, respectively. In a mouse model of PD, we found that selective manipulation of the SNr-projecting GPe-PV neurons alleviated locomotor deficit, whereas manipulation of the PF-projecting GPe-PV neurons rescued the impaired reversal learning. Our findings establish the behavioral importance of two distinct GPe-PV neuronal populations and, thereby, provide a new framework for understanding the circuit basis of different behavioral deficits in the Parkinsonian state.

Natural History, Neuroradiological Workup, and Management Options of Chronic Atlantoaxial Rotatory Fixation Caused by Drug-Induced Cervical Dystonia

Atlantoaxial rotatory fixation (AARF) resulting from drug-induced cervical dystonia (DICD) represents an extremely rare complication of antipsychotic treatment, requiring a comprehensive assessment of pharmacologic therapy and timely radiologic workup. We report a chronic case of Fielding type I, Pang type I AARF secondary to schizophrenia treatment in a 16-year-old girl, along with a review of the literature on the management challenges posed in this condition. In this scenario, torticollis may just represent the tip of the iceberg, and only an effective multidisciplinary approach increases the chances of satisfactory correction with closed reduction, hence avoiding the burden of more invasive treatment options.

Unilateral pallidotomy in the treatment of cervical dystonia: a retrospective observational study

OBJECTIVE

The objective of this study was to assess the efficacy of unilateral pallidotomy in patients with asymmetrical cervical dystonia.

METHODS

This study retrospectively included 25 consecutive patients with asymmetrical cervical dystonia refractory to botulinum toxin injections, who underwent unilateral pallidotomy between January 2015 and April 2017. Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) scores were evaluated preoperatively and 1 week, 3 months, and 6 months postoperatively. The clinical responses were defined as good responders, exhibiting > 50% improvement in the TWSTRS score at 6 months postsurgery, or poor responders, exhibiting < 50% improvement in TWSTRS scores at 6 months postsurgery.

RESULTS

Twelve and 9 patients showed right- and left-side rotation, respectively; 1 and 3 patients had right- and left-side laterocollis, respectively. The mean age of onset and duration of the disease were 40.2 ± 13.9 and 8.9 ± 10.9 years, respectively. Mean TWSTRS scores were 38.4 ± 12.6 (p < 0.001), 17.3 ± 12.4 (p < 0.001), 19.5 ± 13.4 (p < 0.001), and 20.0 ± 14.7 (p < 0.001), preoperatively and 1 week, 3 months, and 6 months postoperatively, respectively. Fourteen patients (56%) demonstrated > 50% improvement in their TWSTRS total score (mean improvement of TWSTRS total score = 70.5%) 6 months postsurgically. Furthermore, preoperative TWSTRS severity score was a prognostic factor (odds ratio 1.37, 95% confidence interval 1.06-1.78, p = 0.003).

CONCLUSIONS

These results suggest that unilateral pallidotomy is an acceptable treatment option for asymmetrical cervical dystonia. Further investigations with a larger number of cases and longer follow-up period are required to confirm these data.

Deep brain stimulation treatment in dystonia: a bibliometric analysis

BACKGROUND

Dystonia is a heterogeneous disorder that, when refractory to medical treatment, may have a favorable response to deep brain stimulation (DBS). A practical way to have an overview of a research domain is through a bibliometric analysis, as it makes it more accessible for researchers and others outside the field to have an idea of its directions and needs.

OBJECTIVE

To analyze the 100 most cited articles in the use of DBS for dystonia treatment in the last 30 years.

METHODS

The research protocol was performed in June 2019 in Elsevier's Scopus database, by retrieving the most cited articles regarding DBS in dystonia. We analyzed authors, year of publication, country, affiliation, and targets of DBS.

RESULTS

Articles are mainly published in Movement Disorders (19%), Journal of Neurosurgery (9%), and Neurology (9%). European countries offer significant contributions (57% of our sample). France (192.5 citations/paper) and Germany (144.1 citations/paper) have the highest citation rates of all countries. The United States contributes with 31% of the articles, with 129.8 citations/paper. The publications are focused on General outcomes (46%), followed by Long-term outcomes (12.5%), and Complications (11%), and the leading type of dystonia researched is idiopathic or inherited, isolated, segmental or generalized dystonia, with 27% of articles and 204.3 citations/paper.

CONCLUSIONS

DBS in dystonia research is mainly published in a handful of scientific journals and focused on the outcomes of the surgery in idiopathic or inherited, isolated, segmental or generalized dystonia, and with globus pallidus internus as the main DBS target.

Cervical Myeloradiculopathy and Atlantoaxial Instability in Cervical Dystonia

OBJECTIVE

Atlantoaxial instability, although rarely reported in the literature, can be associated with cervical dystonia (CD) and may lead to compression of the cord at the craniovertebral junction. We present a case series of 4 patients of longstanding CD with neurologic complications. Treatment strategies and challenges are discussed.

METHODS

Retrospective analysis of 4 cases of longstanding CD with complications of myelopathy or radiculopathy.

RESULTS

The average age at onset of complications was 28 years (range, 17-37). The average duration of CD was 23.75 years. Narrowing of the craniovertebral junction was seen in 3 patients, of which 2 had os odontoideum, and 1 had rotational malalignment at the atlantoaxial joint. One patient had disc desiccation with bulge and intramedullary signal changes in the cord at C3-4 level. Medical treatment was not satisfactory, but botulinum toxin was partly useful in all. One patient had sequelae of myelopathy and did recover partially after deep brain stimulation. Of the 2 patients who underwent surgical fixation with a fusion of the spine, one improved, and the other had no improvement due to irreversible cord damage. The overall outcome was satisfactory only in 2 patients.

CONCLUSIONS

Early-onset CD can lead to cord complications at a young age and at higher levels of the cervical spine and at the cervicovertebral junction. Comprehensive management by a multidisciplinary team is crucial to prevent complications early.

Secondary Worsening Following DYT1 Dystonia Deep Brain Stimulation: A Multi-country Cohort

Objective: To reveal clinical characteristics of suboptimal responses to deep brain stimulation (DBS) in a multi-country DYT1 dystonia cohort. Methods: In this multi-country multi-center retrospective study, we analyzed the clinical data of DYT1 patients who experienced suboptimal responses to DBS defined as <30% improvement in dystonia scales at the last follow-up compared with baseline. We used a literature-driven historical cohort of 112 DYT1 patients for comparison. Results: Approximately 8% of our study cohort (11 out of 132) experienced suboptimal responses to DBS. Compared with the historical cohort, the multi-country cohort with suboptimal responses had a significantly younger age at onset (mean, 7.0 vs. 8.4 years; p = 0.025) and younger age at DBS (mean, 12.0 vs. 18.6 years; p = 0.019). Additionally, cranial involvement was more common in the multi-country cohort (before DBS, 64% vs. 45%, p = 0.074; before or after DBS, 91% vs. 47%, p = 0.001). Mean motor improvement at the last follow-up from baseline were 0% and 66% for the multi-country and historical cohorts, respectively. All 11 patients of the multi-country cohort had generalization of dystonia within 2.5 years after disease onset. All patients experienced dystonia improvement of >30% postoperatively; however, secondary worsening of dystonia commenced between 6 months and 3 years following DBS. The improvement at the last follow-up was less than 30% despite optimally-placed leads, a trial of multiple programming settings, and additional DBS surgeries in all patients. The on-/off-stimulation comparison at the long-term follow-up demonstrated beneficial effects of DBS despite missing the threshold of 30% improvement over baseline. Conclusion: Approximately 8% of patients represent a more aggressive phenotype of DYT1 dystonia characterized by younger age at onset, faster disease progression, and cranial involvement, which seems to be associated with long-term suboptimal responses to DBS (e.g., secondary worsening). This information could be useful for both clinicians and patients in clinical decision making and patient counseling before and following DBS implantations. Patients with this phenotype may have different neuroplasticity, neurogenetics, or possibly distinct neurophysiology.

Stereotactic Selective Thalamotomy for Focal Dystonia with Aid of Depth Microrecording

OBJECTIVE

Long-term effectiveness of selective ventralis intermedius nucleus (VIM)-ventralis oralis nucleus (VO) thalamotomy with depth microrecording for the treatment of focal dystonia was evaluated. The optimal thalamic areas for controlling focal dystonia were studied based on the electrophysiologic and anatomic data.

METHODS

Stereotactic selective VIM-VO thalamotomy with depth microrecording was carried out in 8 patients with focal arm and hand dystonia and in 1 patient with cervical dystonia. Electrophysiologic data on the lateral part of thalamic VIM were studied in patients with focal dystonia. A very small and narrow therapeutic lesion was formed in the shape of a square on the sagittal plane and of an I, rotated V, Y, or inverse Y on the axial plane in the VIM-VO, which covered the kinesthetic response area topographically related to focal dystonia. Patients with arm and hand dystonia were followed up for 4.7 ± 3.0 years and 1 patient with cervical dystonia was followed up for 18.2 years.

RESULTS

Marked improvement of focal dystonia was shown by functional assessment using the Unified Dystonia Rating Scale. Transient dysarthria was recognized in 1 patient. The sequence of body localization of kinesthetic response in the VIM was clearly shown in patients with focal dystonia. Decreases in the amplitude and amplitude ratio of electromyography on the forearm muscles were markedly significant after VIM thalamotomy, but insignificant after VO thalamotomy immediately after VIM thalamotomy.

CONCLUSIONS

Marked reduction of electromyographic tonic discharges of focal dystonia was shown after VIM lesioning. Selective VIM-VO thalamotomy showed good and long-term stable effects for focal dystonia.

Surgical treatment of dystonia

INTRODUCTION

Treatment of dystonia should be individualized and tailored to the specific needs of patients. Surgical treatment is an important option in medically refractory cases. Several issues regarding type of the surgical intervention, targets, and predict factors of benefit are still under debate. Areas covered: To date, several clinical trials have proven the benefit and safety of deep brain stimulation (DBS) for inherited and idiopathic isolated dystonia, whereas there is still insufficient evidence in combined and acquired dystonia. The globus pallidus internus (GPi) is the target with the best evidence, but data on the subthalamic nucleus seems also to be promising. Evidence suggests that younger patients with shorter disease duration experience greater benefit following DBS. Pallidotomy and thalamotomy are currently used in subset of carefully selected patients. The development of MRI-guided focused ultrasound might bring new options to ablation approach in dystonia. Expert commentary: GPi-DBS is effective and safe in isolated dystonia and should not be delayed when symptoms compromise quality of life and functionality. Identifying the best candidates to surgery on acquired and combined dystonias is still necessary. New insights about pathophysiology of dystonia and new technological advances will undoubtedly help to tailor surgery and optimize clinical effects.

King's Parkinson's Disease Pain Scale for Assessment of Pain Relief Following Deep Brain Stimulation for Parkinson's Disease

OBJECTIVE

Pain is a prevalent and debilitating nonmotor symptom of Parkinson's disease (PD) that is often inadequately managed. Deep brain stimulation (DBS) has been shown to relieve pain in PD but an effective method of identifying which types of PD pain respond to DBS has not been established. We examine the effects of DBS on different types of PD pain using the King's Parkinson's disease pain scale (KPDPS), the only validated scale of PD pain.

METHODS

We prospectively followed 18 PD patients undergoing subthalamic nucleus (STN) or Globus pallidus interna (GPi) DBS. Subjects completed the KPDPS, low back disability index (LBDI), and McGill pain questionnaire (MPQ), preoperatively and at six months postoperatively. Subjects underwent the unified Parkinson's disease rating scale-III (UPDRS-III) with preoperative scores ON medication and postoperative scores ON medication/DBS stimulation.

RESULTS

Of the 18 patients, a total of 12 subjects had STN DBS and 6 had GPi DBS. As a group, subjects showed improvement in total KPDPS score at six-month postoperative follow-up (p = 0.004). Fluctuation and nocturnal pain were most significantly improved (p = 0.006, 0.01, respectively). Significant improvements were found in fluctuation-related pain domain following GPi DBS.

CONCLUSIONS

In this pilot study, we are the first group to employ KPDPS to monitor pain relief following DBS in PD patients. We demonstrate that fluctuation-related pain and nocturnal pain significantly improve with DBS. Use of the KPDPS in the future will allow better understanding of how STN and GPi DBS treat PD pain over time.

Deep Brain Stimulation for the Dystonias: Evidence, Knowledge Gaps, and Practical Considerations

BACKGROUND

Deep brain stimulation (DBS) of the globus pallidus internus (GPi-DBS) is among the most effective treatment options for dystonias. Because the term "dystonia" is defined by a characteristic phenomenology of involuntary muscle contractions, which may present with a large clinical and pathogenetic heterogeneity, decision making for or against GPi-DBS can be difficult in individual patients.

METHODS

A search of the PubMed database for research and review articles, focused on "deep brain stimulation" and "dystonia" was used to identify clinical trials and to determine current concepts in the surgical management of dystonia. Patient selection in previous studies was recategorized by the authors using the new dystonia classification put forward by a consensus committee of experts in dystonia research. The evidence and knowledge gaps are summarized and commented by the authors taking into account expert opinion and personal clinical experience for providing practical guidance in patient selection for DBS in dystonia.

RESULTS

The literature review shows that pallidal deep brain stimulation is most effective in patients with isolated dystonia irrespective of the underlying etiology. In contrast, patients with combined dystonias are less likely to benefit from DBS, because the associated neurological symptoms (e.g., hypotonia or ataxia), with the exception of myoclonus, do not respond to pallidal neurostimulation.

CONCLUSIONS

It is important to recognize the clinical features of dystonia, because the distinction between isolated and combined dystonia syndromes may predict the treatment response to pallidal deep brain stimulation. The aim of this review is to help guide clinicians with advising patients about deep brain stimulation therapy for dystonia and refering appropriate candidates to surgical centers.

Deep brain stimulation of the centromedian thalamic nucleus for essential tremor: a case report

The centromedian nucleus (CM) of the thalamus is an important site with anatomical connections to different cortical and subcortical motor areas; however, its role in tremor disorders is not clear, although deep brain stimulation (DBS) of the CM has been described to be effective in the treatment of parkinsonian tremor. We report a case of a patient with medication-refractory essential tremor (ET) who had excellent tremor suppression with DBS of the CM. The CM and the nearby region should be explored as a potential target for the treatment of ET and other forms of tremor.

Electrophysiological interpretations of the clinical response to stimulation parameters of pallidal deep brain stimulation for cervical dystonia

OBJECTIVE

Deep brain stimulation (DBS) at the posterolateral ventral portion of the globus pallidus internus (GPi) has been regarded as a good therapeutic modality. Because the theoretical principle behind the stimulation parameters is yet to be determined, this study aimed to interpret analyses of the stimulation parameters used in our department based on an electrophysiological review.

METHODS

Nineteen patients with medically refractory idiopathic cervical dystonia who underwent GPi DBS were enrolled. The baseline and follow-up parameters were analyzed according to their dependence on time after DBS. The pattern of changes in the stimulation parameters over time, the differences across the four active contacts, and the relationship between the stimulation parameters and clinical benefits were evaluated.

RESULTS

Mean age and disease duration were 50.9 years and 54.7 months, respectively. Mean follow-up duration was 22.6 months. The amplitude and frequency exhibited significant increasing temporal patterns, i.e., a mean amplitude and frequency of 3.1 V and 132.2 Hz at the initial setting and 4.0 V and 142.6 Hz at the last follow-up, respectively. The better clinical response group (clinical improvement rate of 65-100 %) used a narrower pulse width (mean value of 78.4 μs) than the worse clinical response group (clinical improvement rate of 5-60 %, mean of value of 88.6 μs). Active contact at the GPe was used more often in the worse clinical response group than in the better response group.

CONCLUSIONS

Based on electrophysiological considerations, these patterns of stimulation parameters could be interpreted. This interpretation was based on a theoretical understanding of the mechanisms of action of DBS, i.e., that the abnormal neural signal is substituted by an induced neural signal, which is generated by therapeutic DBS.

Degenerative Cervical Myelopathy: Epidemiology, Genetics, and Pathogenesis

STUDY DESIGN

Review.

OBJECTIVE

To formally introduce "degenerative cervical myelopathy" (DCM) as the overarching term to describe the various degenerative conditions of the cervical spine that cause myelopathy. Herein, the epidemiology, pathogenesis, and genetics of conditions falling under this hypernym are carefully described.

SUMMARY OF BACKGROUND DATA

Nontraumatic, degenerative forms of cervical myelopathy represent the commonest cause of spinal cord impairment in adults and include cervical spondylotic myelopathy, ossification of the posterior longitudinal ligament, ossification of the ligamentum flavum, and degenerative disc disease. Unfortunately, there is neither a specific term nor a specific diagnostic International Classification of Diseases, Tenth Revision code to describe this collection of clinical entities. This has resulted in the inconsistent use of diagnostic terms when referring to patients with myelopathy due to degenerative disease of the cervical spine.

METHODS

Narrative review.

RESULTS

The incidence and prevalence of myelopathy due to degeneration of the spine are estimated at a minimum of 41 and 605 per million in North America, respectively. Incidence of cervical spondylotic myelopathy-related hospitalizations has been estimated at 4.04/100,000 person-years, and surgical rates seem to be rising. Pathophysiologically, myelopathy results from static compression, spinal malalignment leading to altered cord tension and vascular supply, and dynamic injury mechanisms. Occupational hazards, including transportation of goods by weight bearing on top of the head, and other risk factors may accelerate DCM development. Potential genetic factors include those related to MMP-2 and collagen IX for degenerative disc disease, and collagen VI and XI for ossification of the posterior longitudinal ligament. In addition, congenital anomalies including spinal stenosis, Down syndrome, and Klippel-Feil syndrome may predispose to the development of DCM.

CONCLUSION

Although DCMs can present as separate diagnostic entities, they are highly interrelated, frequently manifest concomitantly, present similarly from a clinical standpoint, and seem to be in part a response to compensate and improve stability due to progressive age and wear of the cervical spine. The use of the term "degenerative cervical myelopathy" is advocated.

LEVEL OF EVIDENCE

5.

Effectiveness of selective peripheral denervation in combination with pallidal deep brain stimulation for the treatment of cervical dystonia

BACKGROUND

Selective peripheral denervation (SPD) and deep brain stimulation of the globus pallidus (GPi-DBS) are available surgical options for patients with medically refractory cervical dystonia (CD). There are few data available concerning whether patients who have unsatisfactory treatment effects after primary surgery benefit from a different type of subsequent surgery. The aim of this study was to assess whether combining these surgical procedures (SPD plus GPi-DBS) was effective in patients with unsatisfactory treatment effects after their initial surgery.

METHODS

Forty-one patients with medically refractory idiopathic CD underwent SPD and/or GPi-DBS. Patients who were dissatisfied with their primary surgery (SPD or GPi DBS) elected to subsequently undergo a different type of surgery. These patients were assessed with the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS).

RESULTS

SPD alone and GPi-DBS alone were performed in 16 and 21 patients, respectively. Four patients had unsatisfactory treatment effects after the initial surgery and subsequently underwent another type of surgery. Among them, two patients with persistent dystonia after SPD subsequently underwent GPi-DBS, and two other patients who had insufficient treatment effects following GPi-DBS were subsequently treated with SPD. All of these patients experienced sustained improvement from the combined surgical procedures according to the TWSTRS score during a long-term follow-up of 12-90 months.

CONCLUSIONS

Patients with unsatisfactory treatment effects after an SPD or GPi-DBS experienced improvement from subsequently undergoing other types of surgery. Therefore, combined surgical procedures are additional surgical options with good outcomes in the treatment of patients with residual symptoms after their initial surgery.

Pallidal Deep Brain Stimulation in Cervical Dystonia: Clinical Outcome in Four Cases

Objective:

Report on the clinical results following bilateral globus pallidus interna deep brain stimulation in four patients (one female and three males) with severe cervical dystonia, mean age 48 years (range 37-67).

Methods:

All four patients had failed extensive medical and botulinum toxin treatment. The mean duration of the disease was nine years (range 4-15 years). Patients were assessed pre and postoperatively using the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS). Preoperatively, the mean TWSTRS total score was 43.2 (range 28-60.5). Posteroventral pallidal deep brain stimulators were inserted using MRI and microelectrode recording guidance. Last follow-up was 15 months for the four patients.

Results:

Mean reduction in the TWSTRS total scores at last follow- up was 73% (range 61- 85%). Improvement in pain occurred soon after deep brain stimulation surgery. Motor improvement was delayed and prolonged over several months. Frequent adjustment in the stimulation parameters was necessary in the first three months.

Conclusion:

Bilateral pallidal stimulation is effective in management of selected cases of intractable cervical dystonia.

Neuropathic pain and deep brain stimulation

Deep brain stimulation (DBS) is a neurosurgical intervention the efficacy, safety, and utility of which are established in the treatment of Parkinson's disease. For the treatment of chronic, neuropathic pain refractory to medical therapies, many prospective case series have been reported, but few have published findings from patients treated with current standards of neuroimaging and stimulator technology over the last decade . We summarize the history, science, selection, assessment, surgery, programming, and personal clinical experience of DBS of the ventral posterior thalamus, periventricular/periaqueductal gray matter, and latterly rostral anterior cingulate cortex (Cg24) in 113 patients treated at 2 centers (John Radcliffe, Oxford, UK, and Hospital de São João, Porto, Portugal) over 13 years. Several experienced centers continue DBS for chronic pain, with success in selected patients, in particular those with pain after amputation, brachial plexus injury, stroke, and cephalalgias including anesthesia dolorosa. Other successes include pain after multiple sclerosis and spine injury. Somatotopic coverage during awake surgery is important in our technique, with cingulate DBS under general anesthesia considered for whole or hemibody pain, or after unsuccessful DBS of other targets. Findings discussed from neuroimaging modalities, invasive neurophysiological insights from local field potential recording, and autonomic assessments may translate into improved patient selection and enhanced efficacy, encouraging larger clinical trials.

What's new in surgical treatment for dystonia?

It is now established that pallidal deep brain stimulation (DBS) is effective in the treatment of generalized and segmental primary dystonia, although there is still insufficient evidence to support its benefit in focal and secondary dystonia. Because several studies have demonstrated that pallidal DBS improves quality of life (QoL), reduced QoL and disability that are nonresponsive to medical treatment are probably the main factors guiding the decision to consider surgery. Some studies have indicated that young patients with primary dystonia who have shorter disease duration and less severe dystonia are likely to have the best outcome from DBS. Therefore, surgery should not be delayed when disability and QoL are impaired to the extent that justifies the surgical risk. A case-by-case approach is recommended in patients who have secondary dystonia. The globus pallidus internus is considered the best target for dystonia. There are still not enough data about the effectiveness of thalamic, subthalamic nucleus, and premotor cortex stimulation. Targeting with multiple electrodes and intra-individual comparisons of outcomes may help determine which target would be more beneficial. With regard to the role of lesions, pallidotomy for dystonia is still performed in several countries and can play a role in selected patients. New technologies are already available to improve the stimulation programming for DBS patients and to increase battery longevity. In the near future, it is possible that we will be able to shape stimulation settings according to disease type and symptoms. © 2013 Movement Disorder Society.

Deep brain stimulation for dystonia

Deep brain stimulation (DBS) is an effective surgical treatment for medication-refractory movement disorders, and has been approved by the United States Food and Drug Administration for treatment of dystonia. The success of DBS in the treatment of dystonia depends on our understanding of the anatomy and physiology of this disorder and close collaboration between neurosurgeons, neurologists, clinical neurophysiologists, neuroradiologists and neuropsychologists. Currently, pallidal DBS is an established treatment option for medically refractive dystonia. This review is intended to provide a comprehensive review of the use of DBS for dystonia, focusing mainly on the surgical aspects, clinical outcome, MRI findings and side effects of DBS.

Deep brain stimulation for dystonia

Dystonia is a movement disorder characterized by involuntary muscular contractions that generate twisting and repetitive movements and/or abnormal postures. It can affect a few muscle groups (focal dystonia) or spread to most muscles in the body (generalized dystonia). While botulinum toxin injections can be successfully used to treat focal dystonias, medical options for generalized dystonia are very limited. Surgical therapies--and in particular deep brain stimulation (DBS)--are becoming the standard of care for medically intractable, disabling dystonias. Advantages of DBS include reversibility, adjustability and continued access to the therapeutic target. Initial reports describing the use of DBS in generalized dystonia have been very encouraging and experience in the use of DBS to treat various forms of dystonia is continuously growing. This article reviews the issues related to DBS treatment of dystonia, including proper patient selection, surgical approaches to target choice and device implant, a description of the stimulating device and its programming principles, clinical results - with a focus on different outcomes for primary versus secondary and generalized versus cervical dystonia - and complications.

Neuromodulation for dystonia: target and patient selection

Treatment of dystonia refractory to oral medications or botulinum toxin injections includes the use of deep brain stimulation (DBS). Expectations should be established based on patient-related factors, including type of dystonia, genetic cause, target symptoms, age at the time of surgery, disease duration, or the presence of fixed skeletal deformities. Premorbid conditions such as psychiatric illness and cognitive impairment should be considered. Target selection is an emerging issue in DBS for dystonia. Although efficacy has been established for targeting the globus pallidus internus for dystonia, other brain targets such as the subthalamic nucleus, thalamus, or cortex may be promising alternatives.

Deep brain stimulation for dystonia

The few controlled studies that have been carried out have shown that bilateral internal globus pallidum stimulation is a safe and long-term effective treatment for hyperkinetic disorders. However, most recent published data on deep brain stimulation (DBS) for dystonia, applied to different targets and patients, are still mainly from uncontrolled case reports (especially for secondary dystonia). This precludes clear determination of the efficacy of this procedure and the choice of the 'good' target for the 'good' patient. We performed a literature analysis on DBS for dystonia according to the expected outcome. We separated those with good evidence of favourable outcome from those with less predictable outcome. In the former group, we review the main results for primary dystonia (generalised/focal) and highlight recent data on myoclonus-dystonia and tardive dystonia (as they share, with primary dystonia, a marked beneficial effect from pallidal stimulation with good risk/benefit ratio). In the latter group, poor or variable results have been obtained for secondary dystonia (with a focus on heredodegenerative and metabolic disorders). From this overview, the main results and limits for each subgroup of patients that may help in the selection of dystonic patients who will benefit from DBS are discussed.

Deep brain stimulationfor movement disorders

Movement disorders remain the primary indication for the use of intracranial neurostimulation techniques. This review will discuss the history of this technology as well as the mechanisms of action, current clinical indications, and future prospects for the treatment of movement disorders.

Torticollis

Torticollis refers to a twisting of the head and neck caused by a shortened sternocleidomastoid muscle, tipping the head toward the shortened muscle, while rotating the chin in the opposite direction. Torticollis is seen at all ages, from newborns to adults. It can be congenital or postnatally acquired. In this review, we offer a new classification of torticollis, based on its dynamic qualities and pathogenesis. All torticollis can be classified as either nonparoxysmal (nondynamic) or paroxysmal (dynamic). Causes of nonparoxysmal torticollis include congenital muscular; osseous; central nervous system/peripheral nervous system; ocular; and nonmuscular, soft tissue. Causes of paroxysmal torticollis are benign paroxysmal; spasmodic (cervical dystonia); Sandifer syndrome; drugs; increased intracranial pressure; and conversion disorder. The description, epidemiology, clinical presentation, evaluation, treatment, and prognosis of the most clinically significant types of torticollis follow.

Deep brain stimulation for dystonia

The few reported controlled studies show that bilateral stimulation of the globus pallidus interna (GPi) is a safe and effective long-term treatment for hyperkinetic disorders. However, the recently published data on deep brain stimulation (DBS) applied to different targets or patients (especially those with secondary dystonia) are mainly uncontrolled case reports, precluding a clear determination of its efficacy, and providing little guidance as to the choice of a "good" target in a "good" patient. This chapter reviews the literature on DBS in primary dystonia, paying particular attention to the risk:benefit ratio in focal and segmental dystonias (cervical dystonia, cranial dystonia) and to the predictive factors for a good outcome. The chapter also highlights recent data on the marked benefits of the technique in myoclonus dystonia (in which pallidal, as opposed to thalamic, stimulation is more effective) and in tardive dystonia-dyskinesia. Although, the decision to treat appears relatively straightforward in patients with primary dystonia, myoclonus-dystonia, and tardive dystonia who have a normal findings on magnetic resonance imaging and normal cognitive function, there are still no reliable tools to help predict the timescale of postoperative benefit. This chapter provides a comprehensive analysis of the use of the treatment in various types of secondary dystonia, with little to moderate benefit in most cases, based on single cases or small series. Beyond the reduction in the severity of dystonia, the global motor and functional outcome is difficult to determine owing to the paucity of adequate evaluation tools. Because of the large interpatient variability, different targets may be effective depending on the symptoms in each individual.

[Deep brain stimulation for movement disorders]

In the last 25 years deep brain stimulation (DBS) has increased the therapeutic options as well as the pathophysiological understanding of movement disorders (MDS) to an unforeseen extent. This paper covers the state of the art of DBS treatment of Parkinson's disease, tremors, dystonia and other rare forms of MDS and gives an short overview of the mechanisms of action of DBS.

Current and future medical treatment in primary dystonia

Dystonia is a hyperkinetic movement disorder, characterized by involuntary and sustained contractions of opposing muscles causing twisting movements and abnormal postures. It is often a disabling disorder that has a significant impact on physical and psychosocial wellbeing. The medical therapeutic armamentarium used in practice is quite extensive, but for many of these interventions formal proof of efficacy is lacking. Exceptions are the use of botulinum toxin in patients with cervical dystonia, some forms of cranial dystonia (in particular, blepharospasm) and writer's cramp; deep brain stimulation of the pallidum in generalized and segmental dystonia; and high-dose trihexyphenidyl in young patients with segmental and generalized dystonia. In order to move this field forward, we not only need better trials that examine the effect of current treatment interventions, but also a further understanding of the pathophysiology of dystonia as a first step to design and test new therapies that are targeted at the underlying biologic and neurophysiologic mechanisms.

Five-year follow-up of 10 patients treated with globus pallidus internus deep brain stimulation for segmental or multisegmental dystonia

INTRODUCTION

Globus pallidus internus (GPi) deep brain stimulation (DBS) represents a validated, effective, and safe treatment for patients affected by generalized dystonia resistant to conservative treatment. Segmental and multisegmental dystonia have more recently been proposed as further indications for GPi DBS despite the lack of long-term homogenous follow-up. Here we present an original and detailed long-term follow-up (5 years) of a homogeneous population of 11 patients affected by segmental or multisegmental dystonia.

MATERIALS AND METHODS

Ten patients underwent bilateral GPi DBS electrode implantations under a Leksell stereotactic guide, with intraoperative neurophysiological monitoring. The follow-ups at 1, 3 and 5 years were collected using video-BFMDRS for motor and disability scores. The statistical analysis of the results is provided.

RESULTS

We reported a statistically significant improvement in motor and disability overall scores until 5 years after treatment. At the last follow-up, even the single motor subitems were statistically improved.

DISCUSSION

We observed a continuous and statistically significant improvement in all of the motor subitems and in the overall disability score until the 3-year follow-up. These results did not improve any further but they appeared steady at the last follow-up. We also report a significant improvement in the cranial-cervical subitems.

CONCLUSIONS

GPi DBS should definitely be considered a safe and effective treatment also for segmental and multisegmental dystonia even in cases of relevant or prevalent cranial-cervical involvement.

Surgical treatment of dystonia

Dystonia is a neurological condition characterised by abnormal muscle contractions, often causing repetitive twisting movements or abnormal postures. Varying forms of surgical intervention, for dystonia unresponsive to medical therapy, have evolved over the years and have often been associated with poor outcomes and high morbidity. The advent of stereotactic neurosurgery and the success of Deep Brain Stimulation (DBS) in treating a number of movement disorders has revolutionized the surgical treatment for dystonia. This chapter reviews the literature concerning the surgical treatment dystonic conditions, from historical origins to the current use of modern functional neurosurgical techniques.

Parkinson's disease therapeutics: new developments and challenges since the introduction of levodopa

The demonstration that dopamine loss is the key pathological feature of Parkinson's disease (PD), and the subsequent introduction of levodopa have revolutionalized the field of PD therapeutics. This review will discuss the significant progress that has been made in the development of new pharmacological and surgical tools to treat PD motor symptoms since this major breakthrough in the 1960s. However, we will also highlight some of the challenges the field of PD therapeutics has been struggling with during the past decades. The lack of neuroprotective therapies and the limited treatment strategies for the nonmotor symptoms of the disease (ie, cognitive impairments, autonomic dysfunctions, psychiatric disorders, etc.) are among the most pressing issues to be addressed in the years to come. It appears that the combination of early PD nonmotor symptoms with imaging of the nigrostriatal dopaminergic system offers a promising path toward the identification of PD biomarkers, which, once characterized, will set the stage for efficient use of neuroprotective agents that could slow down and alter the course of the disease.