Deep Brain Stimulation in Rare Inherited Dystonias.

BACKGROUND: Rare causes of inherited movement disorders often present with a debilitating phenotype of dystonia, sometimes combined with parkinsonism and other neurological signs. Since these disorders are often resistant to medications, DBS may be considered as a possible treatment. METHODS: Patients with identified genetic diseases (ataxia-telangiectasia, chorea-achantocytosis, dopa-responsive dystonia, congenital nemaline myopathy, methylmalonic aciduria, neuronal ceroid lipofuscinosis, spinocerebellar ataxia types 2 and 3, Wilson's disease, Woodhouse-Sakati syndrome, methylmalonic aciduria, and X trisomy) and disabling dystonia underwent bilateral GPi DBS (bilateral thalamic Vim nucleus in 1 case). The primary outcome was the difference in the Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) between baseline, 1 year and last available follow-up. Preoperative factors such as age at surgery, disease duration at surgery, proportion of life lived with dystonia and severity of dystonia were correlated to the primary outcome. RESULTS: Eleven patients were operated between February 2003 and December 2013. Age and duration of disease at time of surgery were 30 ± 19 and 12.5 ± 15.7 years, respectively. DBS effects on dystonia severity were variable but overall marginally effective, with a mean improvement of 7.9% (p = 0.39) at 1-year follow-up and 16.7% (p = 0.46) at last follow-up (mean 47.3 ± 19.9 months after surgery). No preoperative factors were identified to predict the surgical outcome. CONCLUSION: Our findings support the current knowledge that DBS is modestly effective in treating rare inherited dystonias with a combined phenotype. However, the BFMDRS might not be the best tool to measure outcome in these severely affected patients.

The role of mutations in COL6A3 in isolated dystonia.

Specific mutations in COL6A3 have recently been reported as the cause of isolated recessive dystonia, which is a rare movement disorder. In all patients, at least one mutation was located in Exons 41 and 42. In an attempt to replicate these findings, we assessed by direct sequencing the frequency of rare variants in Exons 41 and 42 of COL6A3 in 955 patients with isolated or combined dystonia or with another movement disorder with dystonic features. We identified nine heterozygous carriers of rare variants including five different missense mutations and an extremely rare synonymous variant. In these nine patients, we sequenced the remaining 41 coding exons of COL6A3 to test for a second mutation in the compound heterozygous state. In only one of them, a second rare variant was identified (Thr732Met + Pro3082Arg). Of note, this patient had been diagnosed with Parkinson´s disease (with dystonic posturing) due to homozygous PINK1 mutations. The COL6A3 mutations clearly did not segregate with the disease in the four affected siblings of this family. Further, there was no indication for a disease-modifying effect of the COL6A3 mutations since disease severity or age at onset did not correlate with the number of COL6A3 mutated alleles in this family. In conjunction with the relatively high frequency of homozygous carriers of reported mutations in publically available databases, our data call a causal role for variants in COL6A3 in isolated dystonia into question.

Gastrointestinal dysfunction in Parkinson's disease.

Our understanding of dysfunction of the gastrointestinal system in patients with Parkinson's disease has increased substantially in the past decade. The entire gastrointestinal tract is affected in these patients, causing complications that range from oral issues, including drooling and swallowing problems, to delays in gastric emptying and constipation. Additionally, small intestinal bacterial overgrowth and Helicobacter pylori infection affect motor fluctuations by interfering with the absorption of antiparkinsonian drugs. The multifaceted role of the gastrointestinal system in Parkinson's disease necessitates a specific and detailed assessment and treatment plan. The presence of pervasive α-synuclein deposition in the gastrointestinal tract strongly implicates this system in the pathogenesis of Parkinson's disease. Future studies elucidating the role of the gastrointestinal tract in the pathological progression of Parkinson's disease might hold potential for early disease detection and development of neuroprotective approaches.

Outcome measures for clinical trials in Parkinson's disease: achievements and shortcomings.

Three areas of intense investigation in Parkinson's disease clinical trials include symptomatic treatment of Parkinsonism, disease-modifying therapy (or neuroprotection), and the prevention and treatment of motor complications of dopaminergic therapy. Difficulty interpreting the results of many studies in recent years has been attributed to problems with the chosen outcome measures. This article reviews the most common outcome measures used, assesses their positive attributes and proposes needs for future research. The Unified Parkinson's disease Rating Scale has been extensively validated and is by far the most common outcome measure used in trials of symptomatic therapy. Ambiguities in the response scale descriptors, poor inter-rater reliability of some items and a lack of items addressing nonmotor features of the disease are being addressed in a revision of the scale. Quality of life outcomes are being used in the minority of clinical trials, and no single generic or disease-specific quality of life measure is being used most frequently. Additional work validating several of the disease-specific instruments is needed. When a generic measure is used, its validity for use in Parkinson's disease must be critically assessed despite its previously established validity in other diseases. With respect to measuring motor complications, significant unmet needs include a consensus as to the best way to define the first motor complication and validating time to the first occurrence of motor complications as a surrogate of future disability and quality of life. Measuring the effectiveness of a potential neuroprotective agent presents unique challenges, particularly since symptomatic effects of the experimental agent or concomitant treatment can obscure any neuroprotective effects. Study designs and biomarkers are being developed that may overcome this problem. Currently, neuroimaging techniques that reflect function of the dopaminergic system are the most promising biomarkers but still require additional validation.