Cerebellum and Ataxias最新文献

Background: Transcranial direct current stimulation (tDCS) of the cerebellum dynamically modulates cerebello-thalamo-cortical excitability in a polarity-specific manner during motor, visuo- motor and cognitive tasks. It remains to be established whether tDCS of the cerebellum impact also on resting-state intrinsically connected networks (ICNs). Such impact would open novel research and therapeutical doors for the neuromodulation of ICNs in human.

Method: We combined tDCS applied over the right cerebellum and fMRI to investigate tDCS- induced resting-state intrinsic functional reconfiguration, using a randomized, sham-controlled design. fMRI data were recorded both before and after real anodal stimulation (2 mA, 20 min) or sham tDCS in 12 right-handed healthy volunteers. We resorted to a region-of-interest static correlational analysis and to a sliding window analysis to assess temporal variations in resting state FC between the cerebellar lobule VII and nodes of the main ICNs.

Results: After real tDCS and compared with sham tDCS, functional changes were observed between the cerebellum and ICNs. Static FC showed enhanced or decreased correlation between cerebellum and brain areas belonging to visual, default-mode (DMN), sensorimotor and salience networks (SN) (p-corrected < 0.05). The temporal variability (TV) of BOLD signal was significantly modified after tDCS displaying in particular a lesser TV between the whole lobule VII and DMN and central executive network and a greater TV between crus 2 and SN. Static and dynamic FC was also modified between cerebellar lobuli.

Conclusion: These results demonstrate short- and long-range static and majorly dynamic effects of tDCS stimulation of the cerebellum affecting distinct resting-state ICNs, as well as intracerebellar functional connectivity, so that tDCS of the cerebellum appears as a non-invasive tool reconfigurating the dynamics of ICNs.

Background and purpose: Immune mediated cerebellar ataxias account for a substantial proportion of all progressive ataxias. A diagnostic serological test is not always available. This is particularly problematic in Primary Autoimmune Cerebellar Ataxia, hence the necessity for diagnostic criteria recently devised and published by an International Task Force. We present our experience in the use of a commercially available indirect immunofluorescence assay, intended to be used for the detection of antibodies associated with paraneoplastic neurological syndromes.

Methods: Retrospective review of patients with ataxia who underwent serological testing using this assay as part of their diagnostic evaluation. We were interested in 3 groups: suspected immune mediated ataxias, genetically confirmed ataxias and patients with cerebellar variant of multi-system atrophy (MSA-C). The indirect immunofluorescence assay was performed using commercially available monkey cerebellum slides and anti-human IgG FITC conjugated antiserum.

Results: A total of 300 patients that had this test and fitted into one of these 3 groups (immune ataxias 190, genetic ataxias 60, MSA-C 50) were identified. The prevalence of positive immunofluorescence but negative immunoblot was 172/190 (91%) in the suspected immune ataxia group, 3/60 (5%) in the genetic group and 2/50 (4%) in the MSA-C group. The difference between the first and the other groups was significant χ² (1, N = 291) = 64.2, p < 00001.

Conclusions: This report demonstrates that a commercially available immunofluorescence assay can be used to provide additional diagnostic aid for suspected immune mediated ataxias and in particular Primary Autoimmune Cerebellar Ataxia where no diagnostic marker exists.

Background: Cerebrotendinous xanthomatosis (CTX) is a rare but treatable neurometabolic disorder of lipid storage and bile acid synthesis. Whilst CTX is said to present with the classic triad of juvenile onset cataracts, tendon xanthomata and progressive ataxia, the diversity of presentation can be such that the diagnosis may be substantially delayed resulting in permanent neurological disability.

Methods: A retrospective review of the clinical characteristics and imaging findings of 4 patients with CTX presenting to the Sheffield Ataxia Centre over a period of 25 years.

Results: Although CTX-related symptoms were present from childhood, the median age at diagnosis was 39 years. Only 1 of the 4 cases had tendon xanthomata, only 2 cases had juvenile onset cataracts and 3 had progressive ataxia with one patient presenting with spastic paraparesis. Serum cholestanol was elevated in all 4 patients, proving to be a reliable diagnostic tool. In addition, cholestanol was raised in the CSF of 2 patients who underwent lumbar puncture. Despite treatment with chenodeoxycholic acid (CDCA) and normalization of serum cholestanol, CSF cholestanol remained high in one patient, necessitating increase in the dose of CDCA. Further adjustments to the dose of CDCA in the patient with raised CSF cholestanol resulted in slowing of progression. Two of the patients who have had the disease for the longest continued to progress, one subsequently dying from pneumonia.

Conclusion: A high index of suspicion for CTX, even in the absence of the classical triad is essential in reaching such diagnosis. The earlier the diagnosis and treatment, the better the outcome.

Background: Erdheim-Chester disease (ECD), a rare disorder of monocyte/macrophage lineage, has been related to cerebellar dysfunction. To increase the awareness of this rare, protean disease, an unusual, myasthenia-like onset of ECD is reported.

Case presentation: A 42-year-old man presented with a 6-year history of mild evening fatigability in his four limbs followed by motor and cognitive symptoms associated with cerebellar atrophy, dentate nuclei and dentato-thalamic pathway degeneration. Magnetic resonance imaging revealed hyperintense signals in T2 and fluid-attenuated inversion recovery sequences within the pons, cerebellar white matter, dentate nuclei and globi pallidi in the absence of any contrast enhancement. Whole-body bone scintigraphy with ⁹⁹Technetium - methylene diphosphonate and fluorodeoxyglucose-positron emission tomography both revealed symmetric uptake in the lower extremities a finding suggestive of a diagnosis of ECD. Histological examination revealed diffuse infiltration of CD 68⁺ histiocytes with foamy cytoplasms in the presence of B-type of Rapidly Accelerated Fibrosarcoma protein kinase (BRAF)^V600E activating mutation in tumor cells.

Conclusion: In patients with myasthenia-like symptoms who test negatively for myasthenia gravis, neurodegenerative diseases, and disorders of the hypothalamus, a diagnosis of ECD should be taken into consideration.

COVID-19 outbreak profoundly impacted on daily-life of patients with neurodegenerative diseases, including those with ataxia. Effects on interventional trials have been recently described. Conversely, changes in physical activity programs, which are crucial in care of ataxic patients, have not been assessed yet.Here we used a structured electronic survey to interview twenty patients with Friedreich ataxia (FA) on changes in physical activity during the lockdown in Italy.Regular physiotherapy was interrupted for most patients and up to 60% of them referred a substantial worsening of self-perceived global health. However, FA patients (especially those mildly affected) adopted voluntarily home-based training strategies and, in 30% of cases, used technology-based tools (TBTs) for exercise.COVID-19 crisis thus disclosed the urgent need to support ataxic patients improving systems for remote physical activity and technology-based assistance.

Background: Transcranial Direct Current Stimulation (tDCS) over the prefrontal cortex has been shown to modulate subjective, neuronal and neuroendocrine responses, particularly in the context of stress processing. However, it is currently unknown whether tDCS stimulation over other brain regions, such as the cerebellum, can similarly affect the stress response. Despite increasing evidence linking the cerebellum to stress-related processing, no studies have investigated the hormonal and behavioural effects of cerebellar tDCS.

Methods: This study tested the hypothesis of a cerebellar tDCS effect on mood, behaviour and cortisol. To do this we employed a single-blind, sham-controlled design to measure performance on a cerebellar-dependent saccadic adaptation task, together with changes in cortisol output and mood, during online anodal and cathodal stimulation. Forty-five participants were included in the analysis. Stimulation groups were matched on demographic variables, potential confounding factors known to affect cortisol levels, mood and a number of personality characteristics.

Results: Results showed that tDCS polarity did not affect cortisol levels or subjective mood, but did affect behaviour. Participants receiving anodal stimulation showed an 8.4% increase in saccadic adaptation, which was significantly larger compared to the cathodal group (1.6%).

Conclusion: The stimulation effect on saccadic adaptation contributes to the current body of literature examining the mechanisms of cerebellar stimulation on associated function. We conclude that further studies are needed to understand whether and how cerebellar tDCS may module stress reactivity under challenge conditions.

Non-invasive cerebellar stimulation (NICS) aims to modulate cerebello-cerebral loops and cerebro-spinal loops, both for research and clinical applications. It is of paramount importance to establish and validate morphological and functional tools to quantify cerebellar reserve, defined as the capacity for restoration and compensation to pathology of the cerebellum. Using NICS without efforts to estimate cerebellar reserve will end up in conflicting results due to the very high heterogeneity of cerebellar disorders encountered in daily practice.

Background: Eye-hand coordination (EHC) is a sophisticated act that requires interconnected processes governing synchronization of ocular and manual motor systems. Precise, timely and skillful movements such as reaching for and grasping small objects depend on the acquisition of high-quality visual information about the environment and simultaneous eye and hand control. Multiple areas in the brainstem and cerebellum, as well as some frontal and parietal structures, have critical roles in the control of eye movements and their coordination with the head. Although both cortex and cerebellum contribute critical elements to normal eye-hand function, differences in these contributions suggest that there may be separable deficits following injury.

Method: As a preliminary assessment for this perspective, we compared eye and hand-movement control in a patient with cortical stroke relative to a patient with cerebellar stroke.

Result: We found the onset of eye and hand movements to be temporally decoupled, with significant decoupling variance in the patient with cerebellar stroke. In contrast, the patient with cortical stroke displayed increased hand spatial errors and less significant temporal decoupling variance. Increased decoupling variance in the patient with cerebellar stroke was primarily due to unstable timing of rapid eye movements, saccades.

Conclusion: These findings highlight a perspective in which facets of eye-hand dyscoordination are dependent on lesion location and may or may not cooperate to varying degrees. Broadly speaking, the results corroborate the general notion that the cerebellum is instrumental to the process of temporal prediction for eye and hand movements, while the cortex is instrumental to the process of spatial prediction, both of which are critical aspects of functional movement control.

Background: Despite the broad development of next-generation sequencing approaches recently, such as whole-exome sequencing, diagnostic workup of adult-onset progressive cerebellar ataxias without remarkable family history and with negative genetic panel testing for SCAs remains a complex and expensive clinical challenge.

Case presentation: In this article, we report a Brazilian man with adult-onset slowly progressive pure cerebellar ataxia, which developed neuropathy and hearing loss after fifteen years of ataxia onset, in which a primary mitochondrial DNA defect (MERRF syndrome - myoclonus epilepsy with ragged-red fibers) was confirmed through muscle biopsy evaluation and whole-exome sequencing.

Conclusions: Mitochondrial disorders are a clinically and genetically complex and heterogenous group of metabolic diseases, resulting from pathogenic variants in the mitochondrial DNA or nuclear DNA. In our case, a correlation with histopathological changes identified on muscle biopsy helped to clarify the definitive diagnosis. Moreover, in neurodegenerative and neurogenetic disorders, some symptoms may be evinced later during disease course. We suggest that late-onset and adult pure undetermined ataxias should be considered and investigated for mitochondrial disorders, particularly MERRF syndrome and other primary mitochondrial DNA defects, together with other more commonly known nuclear genes.

Background: The degenerative cerebellar ataxias comprise a large and heterogeneous group of neurological diseases whose hallmark clinical feature is ataxia, and which are accompanied, to variable degrees, by other features that are attributable to cerebellar dysfunction. Essential tremor (ET) is an exceptionally common neurological disease whose primary motor feature is action tremor, although patients often manifest intention tremor, mild gait ataxia and several other features of cerebellar dysfunction.

Main body: In this paper, we review the abundant evidence derived from clinical, neuroimaging and postmortem studies, linking ET to cerebellar dysfunction. Furthermore, we review the combination of clinical, natural history and postmortem features suggesting that ET is neurodegenerative. We then compare the prevalence of ET (400 - 900 cases per 100,000) to that of the other cerebellar degenerations (ranging from <0.5 - 9 cases per 100,000, and in composite likely to be on the order of 20 cases per 100,000) and conclude that ET is 20 to 45 times more prevalent than all other forms of cerebellar degeneration combined.

Conclusion: Given the data we present, it is logical to conclude that ET is, by far, the most common form of cerebellar degeneration.