Primary dystonia: moribund or viable

Structure of the Golgi apparatus is not influenced by a GAG deletion mutation in the dystonia-associated gene Tor1a

Autosomal-dominant, early-onset DYT1 dystonia is associated with an in-frame deletion of a glutamic acid codon (ΔE) in the TOR1A gene. The gene product, torsinA, is an evolutionarily conserved AAA+ ATPase. The fact that constitutive secretion from patient fibroblasts is suppressed indicates that the ΔE-torsinA protein influences the cellular secretory machinery. However, which component is affected remains unclear. Prompted by recent reports that abnormal protein trafficking through the Golgi apparatus, the major protein-sorting center of the secretory pathway, is sometimes associated with a morphological change in the Golgi, we evaluated the influence of ΔE-torsinA on this organelle. Specifically, we examined its structure by confocal microscopy, in cultures of striatal, cerebral cortical and hippocampal neurons obtained from wild-type, heterozygous and homozygous ΔE-torsinA knock-in mice. In live neurons, the Golgi was assessed following uptake of a fluorescent ceramide analog, and in fixed neurons it was analyzed by immuno-fluorescence staining for the Golgi-marker GM130. Neither staining method indicated genotype-specific differences in the size, staining intensity, shape or localization of the Golgi. Moreover, no genotype-specific difference was observed as the neurons matured in vitro. These results were supported by a lack of genotype-specific differences in GM130 expression levels, as assessed by Western blotting. The Golgi was also disrupted by treatment with brefeldin A, but no genotype-specific differences were found in the immuno-fluorescence staining intensity of GM130. Overall, our results demonstrate that the ΔE-torsinA protein does not drastically influence Golgi morphology in neurons, irrespective of genotype, brain region (among those tested), or maturation stage in culture. While it remains possible that functional changes in the Golgi exist, our findings imply that any such changes are not severe enough to influence its morphology to a degree detectable by light microscopy.

Neuropsychological and Neuropsychiatric Concerns for Deep Brain Stimulation in Dystonia: Preoperative Profiles in a Deep Brain Stimulation Cohort and Postoperative Changes in Three Case Series Reports

Cognitive deficits and psychiatric morbidities are commonly detected in dystonia. Psychiatric disturbances are of particular clinical concern as they not only contribute to poor quality of life and disease associated burden, but also exacerbate motor and cognitive symptoms. Bilateral deep brain stimulation of the globus pallidus internus improves motor symptoms in treatment-resistant dystonia, but its implications for non-motor manifestations are poorly understood. Improved prediction of cognitive and neuropsychiatric outcomes is important in deep brain stimulation (DBS) research and we aim to assess the latter through established assessment tools.

We document the cognitive and neuropsychiatric profiles in 11 primary and 10 secondary dystonia patients attending our DBS clinic. We performed routine multidisciplinary assessments including a comprehensive battery of neuropsychometric tests and detailed neuropsychiatric evaluations. Post-operative assessment outcomes are reported for three patients in case series.

The main cognitive deficit was on the Brixton test of spatial anticipation in primary dystonia. Background medical history included psychiatric illness in 38.1% of the patients with 76% of patients having mood abnormalities confirming elevated psychiatric morbidity in this population. Depressive illness was more prominent in primary, whereas clinically relevant histories in secondary dystonia were varied. Of the 21 patients three were able to perform on selected tests due to extensive limitations of their dystonia. No obvious alteration in intellectual functioning following DBS surgery relative to performance at the time of initial assessment was observed.

The frequency of individual impairments suggests that difficulties associated with dystonia are likely to be of clinical relevance to cognitive functions in the majority of patients. In particular, current findings suggest that executive difficulties related to inductive processes and spatial learning may be a common in primary dystonias. Psychiatric disturbances demand recognition as a central aspect of dystonia as they contribute to overall disease burden, poor quality of life and exacerbated motor disabilities. The available evidence provides overwhelming suggestion that vulnerability to depression is inherent to the dystonia phenotype.

Classification of dystonia in childhood

OBJECTIVE

The most recent international consensus update on dystonia classification proposed a system based on 2 axes, clinical characteristics and aetiology. We aimed to apply this system to Children and Young People (CAYP) selected for movement disorder surgery, and determine if meaningful groupings of cases could be extracted.

METHODS

The 2013 Consensus Committee classification system for dystonia was retrospectively applied to 145 CAYP with dystonic movement disorders. Two-step cluster analysis was applied to the resulting categorisations to identify groupings of CAYP with similar characteristics.

RESULTS

Classification resulted in a total of 43 unique groupings of categorisation. Cluster analysis detected 4 main clusters of CAYP, comparable to previously used patient groupings.

CONCLUSIONS

The 2013 consensus update on dystonia classification can be applied to CAYP with dystonia. The large number of categories provides a wealth of information for the clinician, and also facilitates data driven grouping into clinically meaningful subgroups.