A structural magnetic resonance imaging review of clinical motor outcomes from deep brain stimulation in movement disorders

Patients with movement disorders treated by deep brain stimulation do not always achieve successful therapeutic alleviation of motor symptoms, even in cases where surgery is without complications. Magnetic resonance imaging (MRI) offers methods to investigate structural brain-related factors that may be predictive of clinical motor outcomes. This review aimed to identify features which have been associated with variability in clinical post-operative motor outcomes in patients with Parkinson's disease, dystonia, and essential tremor from structural MRI modalities. We performed a literature search for articles published between 1 January 2000 and 1 April 2022 and identified 5197 articles. Following screening through our inclusion criteria, we identified 60 total studies (39 = Parkinson's disease, 11 = dystonia syndromes and 10 = essential tremor). The review captured a range of structural MRI methods and analysis techniques used to identify factors related to clinical post-operative motor outcomes from deep brain stimulation. Morphometric markers, including volume and cortical thickness were commonly identified in studies focused on patients with Parkinson's disease and dystonia syndromes. Reduced metrics in basal ganglia, sensorimotor and frontal regions showed frequent associations with reduced motor outcomes. Increased structural connectivity to subcortical nuclei, sensorimotor and frontal regions was also associated with greater motor outcomes. In patients with tremor, increased structural connectivity to the cerebellum and cortical motor regions showed high prevalence across studies for greater clinical motor outcomes. In addition, we highlight conceptual issues for studies assessing clinical response with structural MRI and discuss future approaches towards optimizing individualized therapeutic benefits. Although quantitative MRI markers are in their infancy for clinical purposes in movement disorder treatments, structural features obtained from MRI offer the powerful potential to identify candidates who are more likely to benefit from deep brain stimulation and provide insight into the complexity of disorder pathophysiology.

Predicting Outcome in a Cohort of Isolated and Combined Dystonia within Probabilistic Brain Mapping

Background

Probabilistic brain mapping is a promising tool to estimate the expected benefit of pallidal deep brain stimulation (GPi‐DBS) in patients with isolated dystonia (IsoD).

Objectives

To investigate the role of probabilistic mapping in combined dystonia (ComD).

Methods

We rendered the pallidal atlas and the volume of tissue activated (VTA) for a cohort of patients with IsoD (n = 20) and ComD (n = 10) that underwent GPi‐DBS. The VTA was correlated with clinical improvement. Afterwards, each VTA was applied on the previously published probabilistic model (Reich et al., 2019). The correlation between predicted and observed clinical benefit was studied in a linear regression model.

Results

A good correlation between observed and predicted outcome was found for both patients with IsoD (n = 14) and ComD (n = 7) (r² = 0.32; P < 0.05). In ComD, 42% of the variance in DBS response is explained by VTA‐based outcome map.

Conclusion

A probabilistic model would be helpful in clinical practice to circumvent unpredictable and less impressive motor results often found in ComD.

Deep Brain Stimulation of the Globus Pallidus Internus for Secondary Dystonia: Clinical Cases and Systematic Review of the Literature Regarding the Effectiveness of Globus Pallidus Internus versus Subthalamic Nucleus

OBJECTIVE

Deep brain stimulation (DBS) is a frequently applied therapy in primary dystonia. For secondary dystonia, the effects can be less favorable. We share our long-term findings in 9 patients with severe secondary dystonia and discuss these findings in the light of the literature.

METHODS

Patients who had undergone globus pallidus internus (GPi)-DBS for secondary dystonia were included. Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) scores, clinical improvement rates, follow-up periods, stimulation parameters and the need for internal pulse generator replacements were analyzed. The PubMed and Google Scholar databases were searched for articles describing GPi-DBS and subthalamic nucleus (STN)-DBS only for secondary dystonia cases. Keywords were "dystonia," "deep brain stimulation," "GPi," "dystonia," "deep brain stimulation," and "STN."

RESULTS

A total of 9 secondary dystonia patients (5 male, 4 female) had undergone GPi-DBS with microelectrode recording in our units. The mean follow-up period was 29 months. The average BFMDRS score was 58.2 before the surgery, whereas the mean value was 36.5 at the last follow-up of the patients (mean improvement, 39%; minimum, 9%; maximum, 63%). In the literature review, we identified 264 GPi-DBS cases (mean follow-up, 19 months) in 72 different articles about secondary dystonia. The mean BFMDRS improvement rate was 52%. In 146 secondary dystonia cases, reported in 19 articles, STN-DBS was performed. The average follow-up period was 20 months and the improvement in BFMDRS score was 66%.

CONCLUSIONS

Although GPi-DBS has favorable long-term efficacy and safety in the treatment of patients with secondary dystonia, STN seems a promising target for stimulation in patients with secondary dystonia. Further studies including a large number of patients, longer follow-up periods, and more homogenous patients are necessary to establish the optimal target for DBS in the management of secondary dystonias.

Morphological Abnormalities in the Basal Ganglia of Dystonia Patients

OBJECTIVE

The pathophysiology of dystonia is poorly understood. As opposed to secondary forms of dystonia, primary dystonia has long been believed to lack any neuroanatomical substrate. During trajectory planning for DBS, however, conspicuous T2-hyperinstensive signal alterations (SA) were registered within the target region, even in young patients, where ischemia is rare.

METHODS

Fifty MRIs of primary dystonia patients scheduled for DBS were analyzed. Total basal ganglia (BG) volumes, as well as proportionate SA volumes, were measured and compared to 50 age-matched control patients.

RESULTS

There was a 10-fold preponderance of percentaged SA within the globus pallidus (GP) in dystonia patients. The greatest disparity was in young patients <25 years. Also, total BG volume differences were observed with larger GP and markedly smaller putamen and caudate in the dystonia group.

CONCLUSIONS

BG morphology in primary dystonia differed from a control population. Volume reductions of the putamen and caudate may reflect functional degeneration, while volume increases of the GP may indicate overactivity. T2-hyperintensive SA in the GP of young primary dystonia patients, where microvascular lesions are highly unlikely, are striking. Their pathogenic role remains unclear.

Eligibility Criteria for Deep Brain Stimulation in Parkinson’s Disease, Tremor, and Dystonia

In this review, the available evidence to guide clinicians regarding eligibility for deep brain stimulation (DBS) in the main conditions in which these forms of therapy are generally indicated—Parkinson’s disease (PD), tremor, and dystonia—is presented. In general, the literature shows that DBS is effective for PD, essential tremor, and idiopathic dystonia. In these cases, key points in patient selection must include the level of disability and inability to manage symptoms using the best available medical therapy. Results are, however, still not optimal when dealing with other aetiologies, such as secondary tremors and symptomatic dystonia. Also, in PD, issues such as age and neuropsychiatric profile are still debatable parameters. Overall, currently available literature is able to guide physicians on basic aspects of patient selection and indications for DBS; however, a few points are still debatable and controversial. These issues should be refined and clarified in future studies.

Hand disorders in musicians

Like athletes, musicians are vulnerable to musculoskeletal injuries that can be career ending or have a severe negative financial impact. All ages are affected, with a peak incidence in the third and fourth decades. Women are slightly more likely to be affected than men. It is incumbent upon orthopaedic surgeons to be able to complete a thorough physical assessment, be aware of the risk factors associated with musculoskeletal symptoms in musicians, and have a detailed knowledge of the specific syndromes they suffer and their appropriate treatment.

In this paper we review the common hand injuries that afflict musicians and discuss their treatment.

Cite this article: Bone Joint J 2013;95-B:146–50.

Visualization of the internal globus pallidus: sequence and orientation for deep brain stimulation using a standard installation protocol at 3.0 Tesla

BACKGROUND

Deep-brain stimulation (DBS) of the internal globus pallidus (GPi) has shown remarkable therapeutic benefits for treatment-resistant neurological disorders including dystonia and Parkinson's disease (PD). The success of the DBS is critically dependent on the reliable visualization of the GPi. The aim of the study was to evaluate promising 3.0 Tesla magnetic resonance imaging (MRI) methods for pre-stereotactic visualization of the GPi using a standard installation protocol.

METHODS

MRI at 3.0 T of nine healthy individuals and of one patient with PD was acquired (FLAIR, T1-MPRAGE, T2-SPACE, T2*-FLASH2D, susceptibility-weighted imaging mapping (SWI)). Image quality and visualization of the GPi for each sequence were assessed by two neuroradiologists independently using a 6-point scale. Axial, coronal, and sagittal planes of the T2*-FLASH2D images were compared. Inter-rater reliability, contrast-to-noise ratios (CNR) and signal-to-noise ratios (SNR) for the GPi were determined. For illustration, axial T2*-FLASH2D images were fused with a section schema of the Schaltenbrand-Wahren stereotactic atlas.

RESULTS

The GPi was best and reliably visualized in axial and to a lesser degree on coronal T2*-FLASH2D images. No major artifacts in the GPi were observed in any of the sequences. SWI offered a significantly higher CNR for the GPi compared to standard T2-weighted imaging using the standard parameters. The fusion of the axial T2*-FLASH2D images and the atlas projected the GPi clearly in the boundaries of the section schema.

CONCLUSIONS

Using a standard installation protocol at 3.0 T T2*-FLASH2D imaging (particularly axial view) provides optimal and reliable delineation of the GPi.

[Monogenetic dystonia: revisiting the dopaminergic hypothesis]

Dystonias are clinically and genetically heterogeneous neurological disorders that affect movement, and are the focus of much investigative work. The recent identification of mutations in the gene THAP1 in DYT6 dystonia reopens the very interesting question of the in fine involvement of dopamine in the different types of dystonia. In this review, we will go through the recent literature in order to evaluate the many contributions to this theory as well as to highlight the difficulties in identifying a global regulatory pathway for the different forms of this disease that we are just starting to decipher.

Restoration of erect posture by deep brain stimulation of the globus pallidus in disabling dystonic spinal hyperextension

Dystonia is a movement disorder notoriously difficult to treat. While primary dystonia is classically considered to respond well to deep brain stimulation (DBS), treatment of secondary dystonia yields variable results. Patient selection should be done on a case-by-case basis. Clearly, there is a need to accumulate additional information with regard to prognostic factors that may aid neurosurgeons in selecting those patients in whom the disorder is most likely to respond favorably to pallidal DBS.

The authors report the case of a 29-year-old man with secondary dystonia due to perinatal hypoxia. The most prominent symptom was what we have termed ectatocormia—that is, severe, fixed truncal hyperextension and retrocollis, exacerbated by phasic, twisting movements of the trunk and head. This made it impossible for the patient to maintain a normal upright posture or to walk. The patient underwent bilateral DBS of the globus pallidus internus (GPi), and the authors observed impressive improvement in motor abilities and function. The patient's body adopted the normal upright posture and he became able to walk again, 4 months after the commencement of GPi stimulation.

This report, along with others, emphasizes that the GPi as an ideal target for alleviating axial tonic symptoms. The presence of normal MR imaging findings, a phenotypical purity of predominantly dystonic symptoms, and a younger age seem to favor a positive outcome.

Factors predicting improvement in primary generalized dystonia treated by pallidal deep brain stimulation

Despite the beneficial effects of Globus Pallidus internus (GPi) deep brain stimulation (DBS) in patients with primary generalized dystonia (PGD), the degree of improvement varies from one patient to another. The objective of this study was to examine the effects of clinical, anatomical (volume of the GPi), and electrical variables on the postoperative Burke-Fahn-Marsden Dystonia rating scale (BFMDRS) motor score to identify which factors may be predictive of the degree of improvement. We reviewed retrospectively the clinical records of 40 steady-state patients with PGD who had been treated by bilateral GPi lead implantation. The follow-up period was 2 to 8 years. The correlation between the electrical parameters (voltage, impedance, and current) and the clinical outcome was studied. An analysis of covariance was performed to identify factors predictive of the magnitude of improvement. The most influential factors according to the model are as follows: the preoperative BFMDRS score (P < 0.0001); age at surgery (P < 0.0001); the right GPi volume (P = 0.002); the left stimulated GPi volume (P = 0.005). No significant correlation was found between the electrical parameters used and the mean motor scores in steady state.

Deep brain stimulation for pediatric movement disorders

Deep brain stimulation (DBS) has been used for the treatment of tremor and dystonia in adults since 1997. With more than 50,000 treated adults, it has become part of the standard care for pharmacoresistant tremor, Parkinson disease, and dystonias. Dystonias are a heterogeneous group of disorders with intrinsic (genetic) and extrinsic etiologic factors. In children and adults, DBS has been used for the treatment of both primary and secondary dystonias. Pediatric use has been more limited, with only a few experienced centers worldwide. Awake surgery can be safely performed with a dedicated multidisciplinary team approach to help ensure appropriate lead placement. It is incumbent upon us, as physicians, to advise patients and payers on the appropriate use of this technology. Neuromodulation of other disorders, including epilepsy, Tourette syndrome, obsessive-compulsive disorder, and depression, by DBS is under active investigation. Pediatric DBS is still in its early stages; experience will help us refine the indications and techniques for applying this complex technology to our most vulnerable patients, which should lead to our common goal of improving quality of life for our patients and their families. We review the role of DBS and our experience with establishing a dedicated pediatric DBS program.

Deep brain stimulation for secondary dystonia: results in 8 patients

BACKGROUND

Dystonia is a medically intractable condition characterized by involuntary twisting movements and/or abnormal postures. Deep Brain Stimulation (DBS) has been used successfully in various forms of dystonia. In the present study, we report on eight patients with secondary dystonia, treated with DBS in our clinic.

METHOD

Eight patients (five males, three females) underwent DBS for secondary dystonia. The etiology of dystonia was cerebral palsy (n = 2), drug-induced (n = 1), post encephalitis (n = 2) and postanoxic dystonia (n = 3). The functional capacity was evaluated before and after surgery with the use of Burke-Fahn-Mardsen Dystonia Rating Scale (BFM scale), both movement and disability scale (MS and DS, respectively). The target for DBS was the globus pallidus internus (GPi) in 7 patients and in one patient, with postanoxic damaged pallidum, the ventralis oralis anterior (Voa) nucleus. Brain perfusion scintigraphy using Single Photon Emission Computed Tomography (SPECT) was performed in two separate studies for each patient, one in the "off-DBS" and the other in the "on-DBS" state.

FINDINGS

Postoperative both MS and DS scores were found to be significantly lower compared to preoperative scores (p = 0.018 and p = 0.039, respectively). Mean improvement rate after DBS was 41.4% (0-94.3) and 29.5% (0-84.2) in MS and DS scores, respectively. The SPECT Scan, during the "on-DBS" state, showed a decrease in regional cerebral blood flow (rCBF), compared to the "off-DBS" state.

CONCLUSIONS

Our results seem promising in the field of secondary dystonia treatment. More studies with greater number of patients and longer follow-up periods are necessary in order to establish the role of DBS in the management of secondary dystonia. Finally, the significance of brain SPECT imaging in the investigation of dystonia and functional effects of DBS should be further evaluated.