Episodic ataxia type 1: clinical characterization, quality of life and genotype–phenotype correlation

Episodic ataxia type 1 is considered a rare neuronal ion channel disorder characterized by brief attacks of unsteadiness and dizziness with persistent myokymia. To characterize the natural history, develop outcome measures for future clinical trials, and correlate genotype with phenotype, we undertook an international, prospective, cross-sectional study. Thirty-nine individuals (51% male) were enrolled: median age 37 years (range 15–65 years). We identified 10 different pathogenic point mutations in KCNA1 that accounted for the genetic basis of 85% of the cohort. Participants with KCNA1 mutations were more likely to have a positive family history. Analysis of the total cohort showed that the first episode of ataxia occurred before age 20 in all but one patient, with an average age of onset of 7.9 years. Physical exertion, emotional stress and environmental temperature were the most common triggers for attacks. Attack frequency ranged from daily to monthly, even with the same KCNA1genotype. Average attack duration was in the order of minutes. Ten participants (26%) developed permanent cerebellar signs, which were related to disease duration. The average Scale for the Assessment and Rating of Ataxia score (SARA, a standardized measure of cerebellar dysfunction on clinical examination, scores range from 0–40) was an average of 3.15 for all participants (range 0–14), but was only 2 in those with isolated episodic ataxia compared with 7.7 in those with progressive cerebellar ataxia in addition to episodic ataxia. Thirty-seven participants completed the SF-36, a quality of life survey; all eight domain norm-based average scores (mean = 50) were below normal with mental health being the lowest (41.3) in those with mutation positive episodic ataxia type 1. Scores on SF-36 correlated negatively with attack frequency. Of the 39 participants in the study, 33 harboured mutations in KCNA1 whereas the remaining six had no mutation identified. Episodic ataxia type 1 phenocopies have not been described previously and we report their clinical features, which appear to be different to those with a KCNA1mutation. This large prospective study of both genetically confirmed episodic ataxia type 1 and episodic ataxia type 1 phenocopies provides detailed baseline characteristics of these disorders and their impact on participants. We found that attacks had a significant effect on quality of life. Unlike previous studies, we found that a significant number of individuals with genetically confirmed episodic ataxia type 1 (21%) had accumulated persistent cerebellar symptoms and signs. These data will enable the development of outcome measures for clinical trials of treatment.

Brain 2014

Discovering rare diseases: A Kir3.4 mutation causes Andersen–Tawil syndrome by an inhibitory effect on Kir2.1

Objective: To identify other causative genes for Andersen–Tawil syndrome, which is characterized by a triad of periodic paralysis, cardiac arrhythmia, and dysmorphic features. Andersen–Tawil syndrome is caused in a majority of cases by mutations in KCNJ2, which encodes the Kir2.1 subunit of the inwardly rectifying potassium channel.

Methods: The proband exhibited episodic flaccid weakness and a characteristic TU-wave pattern, both suggestive of Andersen–Tawil syndrome, but did not harbor KCNJ2 mutations. We performed exome capture resequencing by restricting the analysis to genes that encode ion channels/associated proteins. The expression of gene products in heart and skeletal muscle tissues was examined by immunoblotting. The functional consequences of the mutation were investigated using a heterologous expression system in Xenopus oocytes, focusing on the interaction with the Kir2.1 subunit.

Results: We identified a mutation in the KCNJ5 gene, which encodes the G-protein–activated inwardly rectifying potassium channel 4 (Kir3.4). Immunoblotting demonstrated significant expression of the Kir3.4 protein in human heart and skeletal muscles. The coexpression of Kir2.1 and mutant Kir3.4 in Xenopus oocytes reduced the inwardly rectifying current significantly compared with that observed in the presence of wild-type Kir3.4.

Conclusions: We propose that KCNJ5 is a second gene causing Andersen–Tawil syndrome. The inhibitory effects of mutant Kir3.4 on inwardly rectifying potassium channels may account for the clinical presentation in both skeletal and heart muscles.

Neurology 2014

Untargeted 1H-NMR metabolomics in CSF

Objectives: To develop a CSF metabolomics signature for motor neuron disease (MND) using ¹H-NMR spectroscopy and to evaluate the predictive value of the profile in a separate cohort.

Methods: We collected CSF from patients with MND and controls and analyzed the samples using ¹H-NMR spectroscopy. We divided the total patient sample in a 4:1 ratio into a training cohort and a test cohort. First, a metabolomics signature was created by statistical modeling in the training cohort, and then the analyses tested the predictive value of the signature in the test cohort. We conducted 10 independent trials for each step. Finally, we identified the compounds that contributed most consistently to the metabolome profile.

Results: Analysis of CSF from 95 patients and 86 controls identified a diagnostic profile for MND (R²X > 22%, R²Y > 93%, Q² > 66%). The best model selected the correct diagnosis with mean probability of 99.31% in the training cohort. The profile discriminated between diagnostic groups with 78.9% sensitivity and 76.5% specificity in the test cohort. Metabolites linked to pathophysiologic pathways in MND (i.e., threonine, histidine, and molecules related to the metabolism of branched amino acids) were among the discriminant compounds.

Conclusion: CSF metabolomics using ¹H-NMR spectroscopy can detect a reproducible metabolic signature for MND with reasonable performance. To our knowledge, this is the first metabolomics study that shows that a validation in separate cohorts is feasible. These data should be considered in future biomarker studies.

Classification of evidence: This study provides Class III evidence that CSF metabolomics accurately distinguishes MNDs from other neurologic diseases

Neurology 2014

Discovering new diseases: CNS inflammation other than multiple sclerosis (CIDOMS): How likely is diagnosis?

The incidence, diagnostic landscape, and workload impact of CNS inflammatory diseases other than multiple sclerosis (MS) (CIDOMS) in a tertiary setting is unknown. We describe a retrospective case series of 64 patients identified over a 2-year period (2009–2010) at the Wessex Neurological Centre in the United Kingdom, accounting for 4% of all patients seen at the center. As expected, neurosarcoidosis and neuromyelitis optica (NMO) were the commonest diagnoses reached (14% each); other diagnoses singly accounted for >10%. However, the likeliest diagnostic outcome (strikingly, in 25%) was nondiagnosis, despite intensive investigation and a mean follow-up period of 3 years. Undiagnosed CIDOMS patients represented the largest workload of the neurology center.

Neurology 2014

tDCS in patients with disorders of consciousness

Objective: We assessed the effects of left dorsolateral prefrontal cortex transcranial direct current stimulation (DLPF-tDCS) on Coma Recovery Scale–Revised (CRS-R) scores in severely brain-damaged patients with disorders of consciousness.

Methods: In a double-blind sham-controlled crossover design, anodal and sham tDCS were delivered in randomized order over the left DLPF cortex for 20 minutes in patients in a vegetative state/unresponsive wakefulness syndrome (VS/UWS) or in a minimally conscious state (MCS) assessed at least 1 week after acute traumatic or nontraumatic insult. Clinical assessments were performed using the CRS-R directly before and after anodal and sham tDCS stimulation. Follow-up outcome data were acquired 12 months after inclusion using the Glasgow Outcome Scale–Extended.

Results: Patients in MCS (n = 30; interval 43 ± 63 mo; 19 traumatic, 11 nontraumatic) showed a significant treatment effect (p = 0.003) as measured by CRS-R total scores. In patients with VS/UWS (n = 25; interval 24 ± 48 mo; 6 traumatic, 19 nontraumatic), no treatment effect was observed (p = 0.952). Thirteen (43%) patients in MCS and 2 (8%) patients in VS/UWS further showed postanodal tDCS-related signs of consciousness, which were observed neither during the pre-tDCS evaluation nor during the pre- or post-sham evaluation (i.e., tDCS responders). Outcome did not differ between tDCS responders and nonresponders.

Conclusion: tDCS over left DLPF cortex may transiently improve signs of consciousness in MCS following severe brain damage as measured by changes in CRS-R total scores.

Classification of evidence: This study provides Class II evidence that short-duration tDCS of the left DLPF cortex transiently improves consciousness as measured by CRS-R assessment in patients with MCS.

Neurology 2014

Breaking News/2: Bevacizumab plus Radiotherapy–Temozolomide for Newly Diagnosed Glioblastoma

BACKGROUND

Standard therapy for newly diagnosed glioblastoma is radiotherapy plus temozolomide. In this phase 3 study, we evaluated the effect of the addition of bevacizumab to radiotherapy–temozolomide for the treatment of newly diagnosed glioblastoma.

METHODS

We randomly assigned patients with supratentorial glioblastoma to receive intravenous bevacizumab (10 mg per kilogram of body weight every 2 weeks) or placebo, plus radiotherapy (2 Gy 5 days a week; maximum, 60 Gy) and oral temozolomide (75 mg per square meter of body-surface area per day) for 6 weeks. After a 28-day treatment break, maintenance bevacizumab (10 mg per kilogram intravenously every 2 weeks) or placebo, plus temozolomide (150 to 200 mg per square meter per day for 5 days), was continued for six 4-week cycles, followed by bevacizumab monotherapy (15 mg per kilogram intravenously every 3 weeks) or placebo until the disease progressed or unacceptable toxic effects developed. The coprimary end points were investigator-assessed progression-free survival and overall survival.

RESULTS

A total of 458 patients were assigned to the bevacizumab group, and 463 patients to the placebo group. The median progression-free survival was longer in the bevacizumab group than in the placebo group (10.6 months vs. 6.2 months; stratified hazard ratio for progression or death, 0.64; 95% confidence interval [CI], 0.55 to 0.74; P<0.001). The benefit with respect to progression-free survival was observed across subgroups. Overall survival did not differ significantly between groups (stratified hazard ratio for death, 0.88; 95% CI, 0.76 to 1.02; P=0.10). The respective overall survival rates with bevacizumab and placebo were 72.4% and 66.3% at 1 year (P=0.049) and 33.9% and 30.1% at 2 years (P=0.24). Baseline health-related quality of life and performance status were maintained longer in the bevacizumab group, and the glucocorticoid requirement was lower. More patients in the bevacizumab group than in the placebo group had grade 3 or higher adverse events (66.8% vs. 51.3%) and grade 3 or higher adverse events often associated with bevacizumab (32.5% vs. 15.8%).

CONCLUSIONS

The addition of bevacizumab to radiotherapy–temozolomide did not improve survival in patients with glioblastoma. Improved progression-free survival and maintenance of baseline quality of life and performance status were observed with bevacizumab; however, the rate of adverse events was higher with bevacizumab than with placebo. (Funded by F. Hoffmann–La Roche; ClinicalTrials.gov number, NCT00943826.)

Breaking News: A Randomized Trial of Bevacizumab for Newly Diagnosed Glioblastoma

BACKGROUND

Concurrent treatment with temozolomide and radiotherapy followed by maintenance temozolomide is the standard of care for patients with newly diagnosed glioblastoma. Bevacizumab, a humanized monoclonal antibody against vascular endothelial growth factor A, is currently approved for recurrent glioblastoma. Whether the addition of bevacizumab would improve survival among patients with newly diagnosed glioblastoma is not known.

METHODS

In this randomized, double-blind, placebo-controlled trial, we treated adults who had centrally confirmed glioblastoma with radiotherapy (60 Gy) and daily temozolomide. Treatment with bevacizumab or placebo began during week 4 of radiotherapy and was continued for up to 12 cycles of maintenance chemotherapy. At disease progression, the assigned treatment was revealed, and bevacizumab therapy could be initiated or continued. The trial was designed to detect a 25% reduction in the risk of death and a 30% reduction in the risk of progression or death, the two coprimary end points, with the addition of bevacizumab.

RESULTS

A total of 978 patients were registered, and 637 underwent randomization. There was no significant difference in the duration of overall survival between the bevacizumab group and the placebo group (median, 15.7 and 16.1 months, respectively; hazard ratio for death in the bevacizumab group, 1.13). Progression-free survival was longer in the bevacizumab group (10.7 months vs. 7.3 months; hazard ratio for progression or death, 0.79). There were modest increases in rates of hypertension, thromboembolic events, intestinal perforation, and neutropenia in the bevacizumab group. Over time, an increased symptom burden, a worse quality of life, and a decline in neurocognitive function were more frequent in the bevacizumab group.

CONCLUSIONS

First-line use of bevacizumab did not improve overall survival in patients with newly diagnosed glioblastoma. Progression-free survival was prolonged but did not reach the prespecified improvement target. (Funded by the National Cancer Institute; ClinicalTrials.gov number,NCT00884741.)

NEJM 2014