Stratification of disease progression in a broad spectrum of degenerative cerebellar ataxias with a clustering method using MRI-based atrophy rates of brain structures

The critical need to develop tools assessing cerebellar reserve for the delivery and assessment of non-invasive cerebellar stimulation

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.

Brain MRI Pattern Recognition in Neurodegeneration With Brain Iron Accumulation

Most neurodegeneration with brain iron accumulation (NBIA) disorders can be distinguished by identifying characteristic changes on magnetic resonance imaging (MRI) in combination with clinical findings. However, a significant number of patients with an NBIA disorder confirmed by genetic testing have MRI features that are atypical for their specific disease. The appearance of specific MRI patterns depends on the stage of the disease and the patient's age at evaluation. MRI interpretation can be challenging because of heterogeneously acquired MRI datasets, individual interpreter bias, and lack of quantitative data. Therefore, optimal acquisition and interpretation of MRI data are needed to better define MRI phenotypes in NBIA disorders. The stepwise approach outlined here may help to identify NBIA disorders and delineate the natural course of MRI-identified changes.

The effect of exercise on high-level mobility in individuals with neurodegenerative disease: a systematic literature review

OBJECTIVE

To investigate the effect of exercise on high-level mobility (i.e. mobility more advanced than independent level walking) in individuals with neurodegenerative disease.

DATA SOURCES

A systematic literature search was conducted in Medline, CINAHL, Scopus, SportDiscus and PEDro.

STUDY SELECTION

Randomised controlled trials of exercise interventions for individuals with neurodegenerative disease, with an outcome measure that contained high-level mobility items were included. High-level mobility items included running, jumping, bounding, stair climbing and backward walking. Outcome measures with high-level mobility items include the High Level Mobility Assessment Tool (HiMAT); Dynamic Gait Index; Rivermead Mobility Index (RMI) or modified RMI; Functional Gait Assessment and the Functional Ambulation Category.

STUDY APPRAISAL

Quality was evaluated with the Cochrane Risk of Bias Tool.

RESULTS

Twenty-four studies with predominantly moderate to low risk of bias met the review criteria. High-level mobility items were included within primary outcome measures for only two studies and secondary outcome measures for 22 studies. Eight types of exercise interventions were investigated within which high-level mobility tasks were not commonly included. In the absence of outcome measures or interventions focused on high-level mobility, findings suggest some benefit from treadmill training for individuals with multiple sclerosis or Parkinson's disease. Progressive resistance training for individuals with multiple sclerosis may also be beneficial. With few studies on other neurodegenerative diseases, further inferences cannot be made.

CONCLUSION

Future studies need to specifically target high-level mobility in the early stages of neurodegenerative disease and determine the impact of high-level mobility interventions on community participation and maintenance of an active lifestyle. Systematic review registration number PROSPERO register for systematic reviews (registration number: CRD42016050362).

Characteristics of Tremor Induced by Lesions of the Cerebellum

It is a clinical experience that acute lesions of the cerebellum induce pathological tremor, which tends to improve. However, quantitative characteristics, imaging correlates, and recovery of cerebellar tremor have not been systematically investigated. We studied the prevalence, quantitative parameters measured with biaxial accelerometry, and recovery of pathological tremor in 68 patients with lesions affecting the cerebellum. We also investigated the correlation between the occurrence and characteristics of tremor and lesion localization using 3D T1-weighted MRI images which were normalized and segmented according to a spatially unbiased atlas template for the cerebellum. Visual assessment detected pathological tremor in 19% while accelerometry in 47% of the patients. Tremor was present both in postural and intentional positions, but never at rest. Two types of pathological tremor were distinguished: (1) low-frequency tremor in 36.76% of patients (center frequency 2.66 ± 1.17 Hz) and (2) normal frequency-high-intensity tremor in 10.29% (center frequency 8.79 ± 1.43 Hz). The size of the lesion did not correlate with the presence or severity of tremor. Involvement of the anterior lobe and lobule VI was related to high tremor intensity. In all followed up patients with acute cerebellar ischemia, the tremor completely recovered within 8 weeks. Our results indicate that cerebellar lesions might induce pathological postural and intentional tremor of 2-3 Hz frequency. Due to its low frequency and low amplitude, quantitative tremorometry is neccessary to properly identify it. There is no tight correlation between lesion localization and quantitative characteristics of cerebellar tremor.