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In cervical dystonia, functional MRI (fMRI) evidence indicates changes in several resting state networks, which revert in part following the botulinum neurotoxin A (BoNT) therapy. Recently, the involvement of the cerebellum in dystonia has gained attention. The aim of our study was to compare connectivity between cerebellar subdivisions and the rest of the brain before and after BoNT treatment. Seventeen patients with cervical dystonia indicated for treatment with BoNT were enrolled (14 female, aged 50.2 ± 8.5 years, range 38–63 years). Clinical and fMRI examinations were carried out before and 4 weeks after BoNT injection. Clinical severity was evaluated using TWSTRS. Functional MRI data were acquired on a 1.5 T scanner during 8 min rest. Seed-based functional connectivity analysis was performed using data extracted from atlas-defined cerebellar areas in both datasets. Clinical scores demonstrated satisfactory BoNT effect. After treatment, connectivity decreased between the vermis lobule VIIIa and the left dorsal mesial frontal cortex. Positive correlations between the connectivity differences and the clinical improvement were detected for the right lobule VI, right crus II, vermis VIIIb and the right lobule IX. Our data provide evidence for modulation of cerebello-cortical connectivity resulting from successful treatment by botulinum neurotoxin.

The link between dystonia and tremor has been known for decades, but the question of whether they are two separate illnesses or just different manifestations of one disease with the same pathophysiological background remains unanswered. We distinguish two types of tremor in dystonia: dystonic tremor (DT), which appears on the body part affected by dystonia, and tremor associated with dystonia (TAWD), which appears in locations where the dystonia does not occur. In this study, the frequency of occurrence of different forms of tremor was determined by clinical examination in a group of adult-onset isolated cervical dystonia (CD) patients treated with regular local injections of botulinum toxin A in our department. In total, 120 patients were included in the study, of which 70 (58.3%) had DT of the head. TAWD was, in all 14 cases (11.7%), observed on the upper limbs, in the form of static or intentional tremor. The aim of this study was to point out the presence of TAWD as one of the clinical signs of CD. DT occurred in more than half of the patients and appears to be a relatively common part of the clinical picture in patients with CD.

The term ‘endemic parkinsonism’ refers to diseases that manifest with a dominant parkinsonian syndrome, which can be typical or atypical, and are present only in a particular geographically defined location or population. Ten phenotypes of endemic parkinsonism are currently known: three in the Western Pacific region; two in the Asian-Oceanic region; one in the Caribbean islands of Guadeloupe and Martinique; and four in Europe. Some of these disease entities seem to be disappearing over time and therefore are probably triggered by unique environmental factors. By contrast, other types persist because they are exclusively genetically determined. Given the geographical clustering and potential overlap in biological and clinical features of these exceptionally interesting diseases, this Review provides a historical reference text and offers current perspectives on each of the 10 phenotypes of endemic parkinsonism. Knowledge obtained from the study of these disease entities supports the hypothesis that both genetic and environmental factors contribute to the development of neurodegenerative diseases, not only in endemic parkinsonism but also in general. At the same time, this understanding suggests useful directions for further research in this area.Endemic parkinsonism occurs only in specific locations or populations. Here, Menšíková et al. describe clusters of endemic parkinsonism and highlight that those linked to neurotoxic environmental factors seem to be disappearing, while genetically determined clusters persist.

The current nosological concept of α-synucleinopathies characterized by the presence of Lewy bodies (LBs) includes Parkinson’s disease (PD), Parkinson’s disease dementia (PDD), and dementia with Lewy bodies (DLB), for which the term “Lewy body disease” (LBD) has recently been proposed due to their considerable clinical and pathological overlap. However, even this term does not seem to describe the true nature of this group of diseases. The subsequent discoveries of α-synuclein (αSyn), SNCA gene, and the introduction of new immunohistochemical methods have started intensive research into the molecular-biological aspects of these diseases. In light of today’s knowledge, the role of LBs in the pathogenesis and classification of these nosological entities remains somewhat uncertain. An increasingly more important role is attributed to other factors as the presence of various LBs precursors, post-translational αSyn modifications, various αSyn strains, the deposition of other pathological proteins (particularly β-amyloid), and the discovery of selective vulnerability of specific cells due to anatomical configuration or synaptic dysfunction. Resulting genetic inputs can undoubtedly be considered as the main essence of these factors. Molecular–genetic data indicate that not only in PD but also in DLB, a unique genetic architecture can be ascertained, predisposing to the development of specific disease phenotypes. The presence of LBs thus remains only a kind of link between these disorders, and the term “diseases with Lewy bodies” therefore results somewhat more accurate.

The complex phenomenological understanding of dystonia has transcended from the clinics to genetics, imaging and neurophysiology. One way in which electrophysiology will impact into the clinics are cases wherein a dystonic clinical presentation may not be typical or a “forme fruste” of the disorder. Indeed, the physiological imprints of dystonia are present regardless of its clinical manifestation. Underpinnings in the understanding of dystonia span from the peripheral, segmental and suprasegmental levels to the cortex, and various electrophysiological tests have been applied in the course of time to elucidate the origin of dystonia pathophysiology. While loss of inhibition remains to be the key finding in this regard, intricacies and variabilities exist, thus leading to a notion that perhaps dystonia should best be gleaned as network disorder. Interestingly, the complex process has now spanned towards the understanding in terms of networks related to the cerebellar circuitry and the neuroplasticity. What is evolving towards a better and cohesive view will be neurophysiology attributes combined with structural dynamic imaging. Such a sound approach will significantly lead to better therapeutic modalities in the future.

Gait disturbance accompanies many neurodegenerative diseases; it is characteristic for Parkinson's disease (PD). Treatment of advanced PD often includes deep brain stimulation (DBS) of the subthalamic nucleus. Regarding gait, previous studies have reported non-significant or conflicting results, possibly related to methodological limitations. The objective of this prospective study was to assess the effects of DBS on biomechanical parameters of gait in patients with PD. Twenty-one patients with advanced PD participated in this prospective study. Gait was examined in all patients using the Zebris FDM-T pressure-sensitive treadmill (Isny, Germany) before DBS implantation and after surgery immediately, further immediately after the start of neurostimulation, and 3 months after neurostimulator activation. We assessed spontaneous gait on a moving treadmill at different speeds. Step length, stance phase of both lower limbs, double-stance phase, and cadence were evaluated. In this study, step length increased, allowing the cadence to decrease. Double-stance phase duration, that is, the most sensitive parameter of gait quality and unsteadiness, was reduced, in gait at a speed of 4.5 km/h and in the narrow-based gaits at 1 km/h (tandem gait), which demonstrates improvement. This study suggests positive effects of DBS treatment on gait in PD patients. Improvement was observed in several biomechanical parameters of gait.

Deep brain stimulation (DBS) is a beneficial procedure for treating idiopathic Parkinson’s disease (PD), essential tremor, and dystonia. The authors describe their set of imaging modalities used for a frameless and fiducial-less method of DBS. CT and MRI scans are obtained preoperatively, and STN parcellation is done based on diffusion tractography. During the surgery, an intraoperative cone-beam computed tomography scan is obtained and merged with the preoperatively-acquired images to place electrodes using a frameless and fiducial-less system. Accuracy is evaluated prospectively. The described sequence of imaging methods shows excellent accuracy compared to the frame-based techniques.

Object: Deep brain stimulation (DBS) is a very useful procedure for the treatment of idiopathic Parkinson’s disease (PD), essential tremor, and dystonia. The authors evaluated the accuracy of the new method used in their center for the placing of DBS electrodes. Electrodes are placed using the intraoperative O-arm™ (Medtronic)-controlled frameless and fiducial-less system, Nexframe™ (Medtronic). Accuracy was evaluated prospectively in eleven consecutive PD patients (22 electrodes). Methods: Eleven adult patients with PD were implanted using the Nexframe system without fiducials and with the intraoperative O-arm (Medtronic) system and StealthStation™ S8 navigation (Medtronic). The implantation of DBS leads was performed using multiple-cell microelectrode recording, and intraoperative test stimulation to determine thresholds for stimulation-induced adverse effects. The accuracy was checked in three different steps: (1) using the intraoperative O-arm image and its fusion with preoperative planning, (2) using multiple-cell microelectrode recording and counting the number of microelectrodes with the signal of the subthalamic nucleus (STN) and finally, (3) total error was calculated according to a postoperative CT control image fused to preoperative planning. Results: The total error of the procedure was 1.79 mm; the radial error and the vector error were 171 mm and 163 mm. Conclusions: Implantation of DBS electrodes using an O-arm navigated frameless and fiducial-less system is a very useful and technically feasible procedure with excellent patient toleration with experienced Nexframe users. The accuracy of the method was confirmed at all three steps, and it is comparable to other published results.