sabato 30 novembre 2013

Development of the PHASES score for prediction of risk of rupture of intracranial aneurysms: a pooled analysis of six prospective cohort studies

The decision of whether to treat incidental intracranial saccular aneurysms is complicated by limitations in current knowledge of their natural history. We combined individual patient data from prospective cohort studies to determine predictors of aneurysm rupture and to construct a risk prediction chart to estimate 5-year aneurysm rupture risk by risk factor status.
We did a systematic review and pooled analysis of individual patient data from 8382 participants in six prospective cohort studies with subarachnoid haemorrhage as outcome. We analysed cumulative rupture rates with Kaplan-Meier curves and assessed predictors with Cox proportional-hazard regression analysis.
Rupture occurred in 230 patients during 29 166 person-years of follow-up. The mean observed 1-year risk of aneurysm rupture was 1·4% (95% CI 1·1—1·6) and the 5-year risk was 3·4% (2·9—4·0). Predictors were age, hypertension, history of subarachnoid haemorrhage, aneurysm size, aneurysm location, and geographical region. In study populations from North America and European countries other than Finland, the estimated 5-year absolute risk of aneurysm rupture ranged from 0·25% in individuals younger than 70 years without vascular risk factors with a small-sized (<7 mm) internal carotid artery aneurysm, to more than 15% in patients aged 70 years or older with hypertension, a history of subarachnoid haemorrhage, and a giant-sized (>20 mm) posterior circulation aneurysm. By comparison with populations from North America and European countries other than Finland, Finnish people had a 3·6-times increased risk of aneurysm rupture and Japanese people a 2·8-times increased risk.
The PHASES score is an easily applicable aid for prediction of the risk of rupture of incidental intracranial aneurysms.

Lancet Neurology 2013

Discovering rare diseases: DOOR syndrome (Deafness, Onychdystrophy, Osteodystrophy, and Mental Retardation) Syndrome

Deafness, onychodystrophy, osteodystrophy, mental retardation, and seizures (DOORS) syndrome is a rare autosomal recessive disorder of unknown cause. We aimed to identify the genetic basis of this syndrome by sequencing most coding exons in affected individuals.
Through a search of available case studies and communication with collaborators, we identified families that included at least one individual with at least three of the five main features of the DOORS syndrome: deafness, onychodystrophy, osteodystrophy, intellectual disability, and seizures. Participants were recruited from 26 centres in 17 countries. Families described in this study were enrolled between Dec 1, 2010, and March 1, 2013. Collaborating physicians enrolling participants obtained clinical information and DNA samples from the affected child and both parents if possible. We did whole-exome sequencing in affected individuals as they were enrolled, until we identified a candidate gene, and Sanger sequencing to confirm mutations. We did expression studies in human fibroblasts from one individual by real-time PCR and western blot analysis, and in mouse tissues by immunohistochemistry and real-time PCR.
26 families were included in the study. We did exome sequencing in the first 17 enrolled families; we screened for TBC1D24 by Sanger sequencing in subsequent families. We identified TBC1D24 mutations in 11 individuals from nine families (by exome sequencing in seven families, and Sanger sequencing in two families). 18 families had individuals with all five main features of DOORS syndrome, and TBC1D24 mutations were identified in half of these families. The seizure types in individuals with TBC1D24mutations included generalised tonic-clonic, complex partial, focal clonic, and infantile spasms. Of the 18 individuals with DOORS syndrome from 17 families without TBC1D24 mutations, eight did not have seizures and three did not have deafness. In expression studies, some mutations abrogated TBC1D24 mRNA stability. We also detected Tbc1d24 expression in mouse phalangeal chondrocytes and calvaria, which suggests a role of TBC1D24 in skeletogenesis.
Our findings suggest that mutations in TBC1D24 seem to be an important cause of DOORS syndrome and can cause diverse phenotypes. Thus, individuals with DOORS syndrome without deafness and seizures but with the other features should still be screened for TBC1D24 mutations. More information is needed to understand the cellular roles of TBC1D24 and identify the genes responsible for DOORS phenotypes in individuals who do not have a mutation in TBC1D24.

Lancet Neurology November 2013

Clinical relevance and functional consequences of the TNFRSF1A multiple sclerosis locus

Objective: We set out to characterize the clinical impact and functional consequences of rs1800693G, the multiple sclerosis (MS) susceptibility allele found in the TNFRSF1A locus.
Methods: We analyzed prospectively collected data on patients with MS to assess the role of the TNFRSF1A locus on disease course and treatment response. Using archival serum samples and freshly isolated monocytes from patients with MS and healthy subjects, we evaluated the effects of rs1800693G and a second risk allele, R92Q, on immune function.
Results: In 772 patients with MS, we see no evidence that rs1800693G strongly influences clinical or radiographic indices of disease course and treatment response; thus, rs1800693G appears to be primarily involved in the onset of MS. At the molecular level, this validated susceptibility allele generates an RNA isoform, TNFRSF1A Δ6, that lacks the transmembrane and cytoplasmic domains. While there was no measurable effect on serum levels of soluble TNFRSF1A, rs1800693G appears to alter the state of monocytes, which demonstrate a more robust transcriptional response of CXCL10 and other genes in response to tumor necrosis factor (TNF)–α. We also report that activation of the TNF-α pathway results in altered expression of 6 other MS susceptibility genes, including T-cell activation rho GTPase activating protein (TAGAP) and regulator of G-protein signaling 1 (RGS1), which are not previously known to be responsive to TNF-α.
Conclusions: The MS rs1800693G susceptibility allele affects the magnitude of monocyte responses to TNF-α stimulation, and the TNF pathway may be one network in which the effect of multiple MS genes becomes integrated.
Neurology 2013

sabato 23 novembre 2013

Breaking News: Mixed Review From FDA Advisory Comittee for Alemtuzumab

The US Food and Drug Administration's (FDA's) Peripheral and Central Nervous System Drugs Advisory Committee gave the new multiple sclerosis (MS) drug alemtuzumab (Lemtrada, Genzyme) a roller coaster ride, not reaching definite conclusions at the end of the day as to whether it should be approved or not.


Because of safety concerns related to aneuploidy, an abnormal number or arrangement of chromosomes, the European Medicines Agency's (EMA's) Committee for Medicinal Products for Human Use (CHMP) has recommended that oral or injectable drugs containing the muscle relaxant thiocolchicoside be restricted across the European Union (EU).
Recommendations include restricting the maximum dose and number of days of treatment for thiocolchicoside-containing drugs, a press release from the EMA said.
Aneuploidy is an established risk factor for impaired male fertility and for teratogenicity, embryotoxicity, or spontaneous abortion.
Thiocolchicoside has been authorized in several EU Member States for use by mouth or injection in the treatment of painful muscular disorders, which could include low back and sciatic pain, cervicobrachial neuralgia, refractory torticollis, or post-traumatic and postoperative pain syndromes. Related medicines are now recommended for short-term use as an add-on treatment in adults and adolescents 16 years of age or older.

Branching Enzyme Deficiency Expanding the Clinical Spectrum

Importance  The neuromuscular presentation of glycogen branching enzyme deficiency includes a severe infantile form and a late-onset variant known as adult polyglucosan body disease. Herein, we describe 2 patients with adult acute onset of fluctuating neurological signs and brain magnetic resonance imaging lesions simulating multiple sclerosis. A better definition of this new clinical entity is needed to facilitate diagnosis.
Objectives  To describe the clinical presentation and progression of a new intermediate variant of glycogen branching enzyme deficiency and to discuss genotype-phenotype correlations.
Design, Setting, and Participants  Clinical, biochemical, morphological, and molecular study of 2 patients followed up for 6 years and 8 years at academic medical centers. The participants were 2 patients of non-Ashkenazi descent with adult acute onset of neurological signs initially diagnosed as multiple sclerosis.
Main Outcomes and Measures  Clinical course, muscle and nerve morphology, longitudinal study of brain magnetic resonance imaging, and glycogen branching enzyme activity and GBE1molecular analysis.
Results  Molecular analysis showed that one patient was homozygous (c.1544G>A) and the other patient was compound heterozygous (c.1544G>A and c.1961-1962delCA) for GBE1 mutations. Residual glycogen branching enzyme activity was 16% and 30% of normal in leukocytes. Both patients manifested acute episodes of transient neurological symptoms, and neurological impairment was mild at age 45 years and 53 years. Brain magnetic resonance imaging revealed nonprogressive white matter lesions and spinocerebellar atrophy similar to typical adult polyglucosan body disease.
Conclusions and Relevance  GBE1 mutations can cause an early adult–onset relapsing-remitting form of polyglucosan body disease distinct from adult polyglucosan body disease in several ways, including younger age at onset, history of infantile liver involvement, and subacute and remitting course simulating multiple sclerosis. This should orient neurologists toward the correct diagnosis.
JAMA Neurology 2013 November

Aquaporin 4 IgG Serostatus and Outcome in Recurrent Longitudinally Extensive Transverse Myelitis

Importance  Studies focused on recurrent longitudinally extensive transverse myelitis (rLETM) are lacking.
Objectives  To determine the aquaporin 4 (AQP4) IgG detection rate using recombinant human APQ4-based assays in sequential serum specimens collected from patients with rLETM categorized as negative by first-generation tissue-based indirect immunofluorescence (IIF) assay and to define the clinical characteristics and motor disability outcomes in AQP4-IgG–positive rLETM.
Design, Setting, and Participants  A search of the Mayo Clinic computerized central diagnostic index (October 1, 2005, through November 30, 2011), cross-linked with the Neuroimmunology Laboratory database, identified 48 patients with rLETM, of whom 36 (75%) were positive and 12 (25%) negative for neuromyelitis optica (NMO) IgG (per IIF of serial serum specimens). Stored serum specimens from “seronegative” patients were retested with recombinant human AQP4-based assays, including enzyme-linked immunosorbent, transfected cell-based, and fluorescence-activated cell-sorting assays. Control patients included 140 AQP4-IgG–positive patients with NMO, of whom a subgroup of 20 initially presented with 2 attacks of transverse myelitis (rLETM-onset NMO).
Main Outcomes and Measures  AQP4-IgG serostatus, clinical characteristics, and Expanded Disability Status Scale score.
Results  Six patients with negative IIF results were reclassified as AQP4-IgG positive, yielding an overall AQP4-IgG seropositivity rate of 89%. Fluorescence-activated cell-sorting, cell-based, and enzyme-linked immunosorbent assays improved the detection rate to 89%, 85%, and 81%, respectively. The female to male ratio was 2:3 for AQP4-IgG–negative rLETM and 5:1 for AQP4-IgG–positive patients. The AQP4-IgG–positive patients with rLETM or rLETM-onset NMO were similar in age at onset, sex ratio, attack severity, relapse rate, and motor disability. From Kaplan-Meier analyses, 36% of AQP4-IgG–positive patients with rLETM are anticipated to need a cane to walk within 5 years after onset. For patients with rLETM-onset NMO, the median time from onset to first optic neuritis attack (54 months) was similar to the median disease duration for AQP4-IgG–positive patients with rLETM (59 months). The median number of attacks was 3 for AQP4-IgG–positive patients with rLETM (range, 2-22), and the first optic neuritis attack for those with rLETM-onset NMO followed a median of 3 myelitis attacks (range, 2-19). Immunosuppressant therapy reduced the relapse rate in both AQP4-IgG–positive and AQP4-IgG–negative patients with rLETM.
Conclusions and Relevance  Recombinant antigen–based assays significantly increase AQP4-IgG detection in patients with rLETM, and AQP4-IgG–negative adults with rLETM are rare. Evolution to NMO can be anticipated in AQP4-IgG–positive patients. Early initiation of immunotherapy may result in a more favorable motor outcome.
JAMA Neurology November 2013

Diagnostic Exome Sequencing: A New Paradigm in Neurology

Genomic tools have evolved with remarkable rapidity, but their clinical relevance and application have lagged behind. Now, consistent clinical applications have finally arrived and bring with them the promise of identifying the underlying causes of complex neurological disorders in a patient-specific manner.

Neuron FREE FEATURED ARTICLE 2013 November

The Pathobiology of Vascular Dementia

Vascular cognitive impairment defines alterations in cognition, ranging from subtle deficits to full-blown dementia, attributable to cerebrovascular causes. Often coexisting with Alzheimer’s disease, mixed vascular and neurodegenerative dementia has emerged as the leading cause of age-related cognitive impairment. Central to the disease mechanism is the crucial role that cerebral blood vessels play in brain health, not only for the delivery of oxygen and nutrients, but also for the trophic signaling that inextricably links the well-being of neurons and glia to that of cerebrovascular cells. This review will examine how vascular damage disrupts these vital homeostatic interactions, focusing on the hemispheric white matter, a region at heightened risk for vascular damage, and on the interplay between vascular factors and Alzheimer’s disease. Finally, preventative and therapeutic prospects will be examined, highlighting the importance of midlife vascular risk factor control in the prevention of late-life dementia.

Neuron FREE ARTICLE November 2013

Hypertrophic pachymeningitis: significance of myeloperoxidase anti-neutrophil cytoplasmic antibody

The aim of this study was to elucidate the characteristics, pathogenesis and treatment strategy of hypertrophic pachymeningitis that is associated with myeloperoxidase anti-neutrophil cytoplasmic antibody (ANCA). We retrospectively investigated clinical, radiological, immunological and pathological profiles of 36 patients with immune-mediated or idiopathic hypertrophic pachymeningitis, including 17 patients with myeloperoxidase-ANCA, four patients with proteinase 3-ANCA, six patients with other immune-mediated disorders, and nine patients with ‘idiopathic’ variety. Myeloperoxidase-ANCA-positive hypertrophic pachymeningitis was characterized by: (i) an elderly female predominance; (ii) 82% of patients diagnosed with granulomatosis with polyangiitis (previously known as Wegener’s granulomatosis) according to Watts’ algorithm; (iii) a high frequency of patients with lesions limited to the dura mater and upper airways, developing headaches, chronic sinusitis, otitis media or mastoiditis; (iv) a low frequency of patients with the ‘classical or generalized form’ of granulomatosis with polyangiitis involving the entire upper and lower airways and kidney, or progressing to generalized disease, in contrast to proteinase 3-ANCA-positive hypertrophic pachymeningitis; (v) less severe neurological damage according to the modified Rankin Scale and low disease activity according to the Birmingham Vasculitis Activity Score compared with proteinase 3-ANCA-positive hypertrophic pachymeningitis; (vi) increased levels of CXCL10, CXCL8 and interleukin 6 in cerebrospinal fluids, and increased numbers of T cells, neutrophils, eosinophils, plasma cells and monocytes/macrophages in autopsied or biopsied dura mater with pachymeningitis, suggesting TH1-predominant granulomatous lesions in hypertrophic pachymeningitis, as previously reported in pulmonary or renal lesions of granulomatosis with polyangiitis; and (vii) greater efficacy of combination therapy with prednisolone and cyclophosphamide compared with monotherapy with prednisolone. Proteinase 3-ANCA may be considered a marker for more severe neurological damage, higher disease activity and a higher frequency of the generalized form compared with myeloperoxidase-ANCA-positive hypertrophic pachymeningitis. However, categorization into ‘granulomatosis with polyangiitis’ according to Watts’ algorithm and immunological or pathological features were common in both proteinase 3- and myeloperoxidase-ANCA-positive hypertrophic pachymeningitis. These data indicate that most patients with myeloperoxidase-ANCA-positive hypertrophic pachymeningitis should be categorized as having the central nervous system-limited form of ANCA-associated vasculitis, consistent with the concept of ophthalmic-, pulmonary- or renal-limited vasculitis.

Brain 2013 November

Treatable childhood neuronopathy caused by mutations in riboflavin transporter RFVT2

Childhood onset motor neuron diseases or neuronopathies are a clinically heterogeneous group of disorders. A particularly severe subgroup first described in 1894, and subsequently called Brown-Vialetto-Van Laere syndrome, is characterized by progressive pontobulbar palsy, sensorineural hearing loss and respiratory insufficiency. There has been no treatment for this progressive neurodegenerative disorder, which leads to respiratory failure and usually death during childhood. We recently reported the identification of SLC52A2, encoding riboflavin transporter RFVT2, as a new causative gene for Brown-Vialetto-Van Laere syndrome. We used both exome and Sanger sequencing to identify SLC52A2mutations in patients presenting with cranial neuropathies and sensorimotor neuropathy with or without respiratory insufficiency. We undertook clinical, neurophysiological and biochemical characterization of patients with mutations in SLC52A2, functionally analysed the most prevalent mutations and initiated a regimen of high-dose oral riboflavin. We identified 18 patients from 13 families with compound heterozygous or homozygous mutations in SLC52A2. Affected individuals share a core phenotype of rapidly progressive axonal sensorimotor neuropathy (manifesting with sensory ataxia, severe weakness of the upper limbs and axial muscles with distinctly preserved strength of the lower limbs), hearing loss, optic atrophy and respiratory insufficiency. We demonstrate that SLC52A2 mutations cause reduced riboflavin uptake and reduced riboflavin transporter protein expression, and we report the response to high-dose oral riboflavin therapy in patients with SLC52A2 mutations, including significant and sustained clinical and biochemical improvements in two patients and preliminary clinical response data in 13 patients with associated biochemical improvements in 10 patients. The clinical and biochemical responses of this SLC52A2-specific cohort suggest that riboflavin supplementation can ameliorate the progression of this neurodegenerative condition, particularly when initiated soon after the onset of symptoms.

Brain 2013 November 

Bringing rigour to translational medicine

Translational neuroscience is in the doldrums. The stroke research community was among the first to recognize that the motivations inherent in our system of research can cause investigators to take shortcuts, and can introduce bias and reduce generalizability, all of which leads ultimately to the recurrent failure of apparently useful drug candidates in clinical trials. Here, we review the evidence for these problems in stroke research, where they have been most studied, and in other translational research domains, which seem to be bedevilled by the same issues. We argue that better scientific training and simple changes to the way that we fund, assess and publish research findings could reduce wasted investment, speed drug development, and create a healthier research environment. For 'phase III' preclinical studies—that is, those studies that build the final justification for conducting a clinical trial—we argue for a need to apply the same attention to detail, experimental rigour and statistical power in our animal experiments as in the clinical trials themselves
Nature Reviews Neurology November 2013

Amyotrophic lateral sclerosis-a model of corticofugal axonal spread.

The pathological process underlying amyotrophic lateral sclerosis (ALS) is associated with the formation of cytoplasmic inclusions consisting mainly of phosphorylated 43-kDa transactive response DNA-binding protein (pTDP-43), which plays an essential part in the pathogenesis of ALS. Preliminary evidence indicates that neuronal involvement progresses at different rates, but in a similar sequence, in different patients with ALS. This observation supports the emerging concept of prion-like propagation of abnormal proteins in noninfectious neurodegenerative diseases. Although the distance between involved regions is often considerable, the affected neurons are connected by axonal projections, indicating that physical contacts between nerve cells along axons are important for dissemination of ALS pathology. This article posits that the trajectory of the spreading pattern is consistent with the induction and dissemination of pTDP-43 pathology chiefly from cortical neuronal projections, via axonal transport, through synaptic contacts to the spinal cord and other regions of the brain.

Nature Reviews Neurology November 2013

Quality improvement in neurology: Amyotrophic lateral sclerosis quality measures Report of the Quality Measurement and Reporting Subcommittee of the American Academy of Neurology

Amyotrophic lateral sclerosis (ALS) is a lethal, progressive neurodegenerative disease characterized by loss of motor neurons.1 Patients with ALS lose function in the limbs, speech, swallowing, and breathing muscles. The cause of the disease is still not known for most patients. Approximately 25,000 people in the United States have ALS, and 5,000 people are diagnosed with ALS annually in the United States.1 Most patients die from respiratory failure 2 to 5 years after onset of symptoms. Cognitive dysfunction is seen in 20 to 50% of patients.2 The disease burden for patients and caregivers is enormous. The average cost of care has been estimated at $50,000 per patient per year.3

Neurology 2013 November

Fibroblast growth factor 21 is a sensitive biomarker of mitochondrial disease

Objective: To prospectively determine the reliability and validity of serum fibroblast growth factor 21 (FGF-21) as a biomarker for mitochondrial disease in a cross-sectional cohort of adults with mitochondrial disease from a specialist primary care and tertiary referral clinic.
Methods: We recruited 140 subjects, including 54 adults with mitochondrial disease, 20 patients with nonmitochondrial neuromuscular disease, and 66 control subjects, between November 2011 and October 2012. We compared serum FGF-21 concentrations to classical biomarkers, serum creatine kinase, lactate, pyruvate, and lactate to pyruvate ratio, to determine its validity and reliability as a biomarker of mitochondrial disease. We determined the sensitivity, odds ratio (OR), and overall reliability of FGF-21 as a marker of mitochondrial disease using statistical analyses.
Results: Median serum FGF-21 concentrations were significantly elevated in patients with mitochondrial disease and differed significantly between all experimental groups. FGF-21 showed a markedly higher diagnostic OR (45.7 [95% confidence interval = 12.6–166.5], p < 0.0001) when compared to other biomarkers and was the best predictor of disease according to sensitivity and receiver operating characteristic curve analysis. After multivariate logistic regression analysis controlling for potential confounders, FGF-21 was the only measured parameter capable of predicting mitochondrial disease.
Conclusion: This prospective study establishes serum FGF-21 levels as a sensitive biomarker of mitochondrial disease and demonstrates that they are the best predictor of this disorder when compared to serum levels of classical indicators: creatine kinase, lactate, pyruvate, and the lactate to pyruvate ratio.

Neurology 2013 November 

Episodic weakness due to mitochondrial DNA MT-ATP6/8 mutations

Objective: To report that homoplasmic deleterious mutations in the mitochondrial DNA MT-ATP6/8 genes may be responsible for acute episodes of limb weakness mimicking periodic paralysis due to channelopathies and dramatically responding to acetazolamide.
Methods: Mitochondrial DNA sequencing and restriction PCR, oxidative phosphorylation functional assays, reactive oxygen species metabolism, and patch-clamp technique in cultured skin fibroblasts.
Results: Occurrence of a typical MELAS (mitochondrial encephalopathy with lactic acidosis and stroke-like episodes) syndrome in a single member of a large pedigree with episodic weakness associated with a later-onset distal motor neuropathy led to the disclosure of 2 deleterious mitochondrial DNA mutations. The MT-ATP6 m.9185T>C p.Leu220Pro mutation, previously associated with Leigh syndrome, was present in all family members, while the MT-TL1 m.3271T>C mutation, a known cause of MELAS syndrome, was observed in the sole patient with MELAS presentation. Significant defect of complexes V and I as well as oxidative stress were observed in both primary fibroblasts and cybrid cells with 100% m.9185T>C mutation. Permanent plasma membrane depolarization and altered permeability to K+ in fibroblasts provided a link with the paralysis episodes. Screening of 9 patients, based on their clinical phenotype, identified 4 patients with similar deleterious MT-ATP6 mutations (twice m.9185T>C and once m.9176T>C or m.8893T>C). A fifth patient presented with an original potentially deleterious MT-ATP8 mutation (m.8403T>C). All mutations were associated with almost-normal complex V activity but significant oxidative stress and permanent plasma membrane depolarization.
Conclusion: Homoplasmic mutations in the MT-ATP6/8 genes may cause episodic weakness responding to acetazolamide treatment.
Neurology 2013 November

sabato 16 novembre 2013

Advances in peripheral nerve regeneration

Rodent models of nerve injury have increased our understanding of peripheral nerve regeneration, but clinical applications have been scarce, partly because such models do not adequately recapitulate the situation in humans. In human injuries, axons are often required to extend over much longer distances than in mice, and injury leaves distal nerve fibres and target tissues without axonal contact for extended amounts of time. Distal Schwann cells undergo atrophy owing to the lack of contact with proximal neurons, which results in reduced expression of neurotrophic growth factors, changes in the extracellular matrix and loss of Schwann cell basal lamina, all of which hamper axonal extension. Furthermore, atrophy and denervation-related changes in target tissues make good functional recovery difficult to achieve even when axons regenerate all the way to the target tissue. To improve functional outcomes in humans, strategies to increase the speed of axonal growth, maintain Schwann cells in a healthy, repair-capable state and keep target tissues receptive to reinnervation are needed. Use of rodent models of chronic denervation will facilitate our understanding of the molecular mechanisms of peripheral nerve regeneration and create the potential to test therapeutic advances.

Nature Reviews Neurology 2013

Genomewide association study in cervical dystonia demonstrates possible association with sodium leak channel

Dystonia is a common movement disorder. A number of monogenic causes have been identified. However, the majority of dystonia cases are not explained by single gene defects. Cervical dystonia is one of the commonest forms without genetic causes identified. This pilot study aimed to identify large effect-size risk loci in cervical dystonia. A genomewide association study (GWAS) was performed. British resident cervical dystonia patients of European descent were genotyped using the Illumina-610-Quad. Comparison was made with controls of European descent from the Wellcome Trust Case Control Consortium using logistic regression algorithm from PLINK. SNPs not genotyped by the array were imputed with 1000 Genomes Project data using the MaCH algorithm and minimac. Postimputation analysis was done with the mach2dat algorithm using a logistic regression model. After quality control measures, 212 cases were compared with 5173 controls. No single SNP passed the genomewide significant level of 5 × 10−8 in the analysis of genotyped SNP in PLINK. Postimputation, there were 5 clusters of SNPs that had P value <5 × 10−6, and the best cluster of SNPs was found near exon 1 ofNALCN, (sodium leak channel) with P = 9.76 × 10−7. Several potential regions were found in the GWAS and imputation analysis. The lowest P value was found in NALCN. Dysfunction of this ion channel is a plausible cause for dystonia. Further replication in another cohort is needed to confirm this finding. We make this data publicly available to encourage further analyses of this disorder. 

Movement Disorder  2013 

Cortical Effects of Deep Brain Stimulation Implications for Pathogenesis and Treatment of Parkinson

High-frequency electrical stimulation that targets the subthalamic nucleus has proved to be beneficial in alleviating the motor symptoms in many patients with Parkinson disease. The mechanism of action for this paradigm of deep brain stimulation is still not fully understood, and this is, in part, attributed to the fact that there are diverse cellular elements at the stimulation site that could bring about local and distal effects. Recent studies in both human and animal models strongly suggest that the activity in the cortex, especially in the motor cortical areas, is directly altered by deep brain stimulation by signals traveling in an antidromic fashion from the subthalamic nucleus. Herein, we discuss the evidence for this proposition, as well as the mechanism by which antidromic activation desynchronizes motor cortical activity. The implications of these new findings for the pathogenesis and treatment of Parkinson disease are highlighted.

JAMA Neurology 2013 November

Online First > Full Content is available to subscribers Subscribe/Learn More Original Investigation | November 04, 2013 Clinical Worsening in Reversible Cerebral Vasoconstriction Syndrome

Importance  Reversible cerebral vasoconstriction syndrome (RCVS) is characterized by recurrent thunderclap headaches and evidence of vasoconstriction with subsequent resolution. The clinical course of RCVS is traditionally considered monophasic and benign. However, recurrent episodes of focal neurological symptoms have been described after initial presentation.
Objective  To define the frequency, timing, and consequences of clinical worsening in patients with diagnosis of RCVS.
Design, Setting, and Participants  Retrospective observational study of consecutive patients with RCVS at 2 referral institutions for neurological disease.
Main Outcome and Measure  Clinical worsening after diagnosis of RCVS. We defined clinical worsening as new permanent or transient neurological deficits (compared with presenting signs and symptoms) or new onset of seizures. We performed a logistic regression analysis to assess associations between patient characteristics and clinical worsening. Functional outcome was assessed at 1 to 3 months using the modified Rankin score.
Results  We identified 59 patients (median age, 47 years; interquartile range, 32-54 years) with RCVS. Twenty patients (34%) experienced clinical worsening after a median of 2.5 days (range, several hours to 14 days). Eight of the 20 patients who worsened had permanent deficits, including 4 who died. We did not find an association between age, sex, smoking, migraine, acute or chronic hypertension, peripartum state, or use of serotonergic drugs with clinical worsening. Clinical worsening was associated with radiological infarction (P = .001) and worse functional outcome (P < .004). Functional outcome was favorable (modified Rankin score 0-2) in 51 patients (86.4%).
Conclusions and Relevance  Clinical worsening after diagnosis is common in patients with RCVS. Thus, RCVS is self-limited but not strictly monophasic. Most patients have a very favorable outcome, but clinical worsening may result in permanent deficits.

JAMA November 2013

Biochemical Characterization of Patients With In-Frame or Out-of-Frame DMD Deletions Pertinent to Exon 44 or 45 Skipping

Importance  In Duchenne muscular dystrophy (DMD), the reading frame of an out-of-frame DMDdeletion can be repaired by antisense oligonucleotide (AO)–mediated exon skipping. This creates a shorter dystrophin protein, similar to those expressed in the milder Becker muscular dystrophy (BMD). The skipping of some exons may be more efficacious than others. Patients with exon 44 or 45 skippable deletions (AOs in clinical development) have a less predictable phenotype than those skippable for exon 51, a group in advanced clinical trials. A way to predict the potential of AOs is the study of patients with BMD who have deletions that naturally mimic those that would be achieved by exon skipping.
Objective  To quantify dystrophin messenger RNA (mRNA) and protein expression in patients withDMD deletions treatable by, or mimicking, exon 44 or 45 skipping.
Design, Setting, and Participants  Retrospective study of nondystrophic controls (n = 2), patients with DMD (n = 5), patients with intermediate muscular dystrophy (n = 3), and patients with BMD (n = 13) at 4 university-based academic centers and pediatric hospitals. Biochemical analysis of existing muscle biopsies was correlated with the severity of the skeletal muscle phenotype.
Main Outcomes and Measures  Dystrophin mRNA and protein expression.
Results  Patients with DMD who have out-of-frame deletions skippable for exon 44 or 45 had an elevated number of revertant and trace dystrophin expression (approximately 19% of control, using quantitative immunohistochemistry) with 4 of 9 patients presenting with an intermediate muscular dystrophy phenotype (3 patients) or a BMD-like phenotype (1 patient). Corresponding in-frame deletions presented with predominantly mild BMD phenotypes and lower dystrophin levels (approximately 42% of control) than patients with BMD modeling exon 51 skipping (approximately 80% of control). All 12 patients with in-frame deletions had a stable transcript compared with 2 of 9 patients with out-of-frame deletions (who had intermediate muscular dystrophy and BMD phenotypes).
Conclusions and Relevance  Exon 44 or 45 skipping will likely yield lower levels of dystrophin than exon 51 skipping, although the resulting protein is functional enough to often maintain a mild BMD phenotype. Dystrophin transcript stability is an important indicator of dystrophin expression, and transcript instability in DMD compared with BMD should be explored as a potential biomarker of response to AOs. This study is beneficial for the planning, execution, and analysis of clinical trials for exon 44 and 45 skipping.

JAMA Neurology 2013

Amyloid Imaging With Carbon 11–Labeled Pittsburgh Compound B for Traumatic Brain Injury

Objectives  To image amyloid deposition in patients with traumatic brain injury (TBI) using carbon 11–labeled Pittsburgh Compound B ([11C]PiB) positron emission tomography (PET) and to validate these findings using tritium-labeled PiB ([3H]PiB) autoradiography and immunocytochemistry in autopsy-acquired tissue.
Design, Setting, and Participants  In vivo PET at tertiary neuroscience referral center and ex vivo immunocytochemistry of autopsy-acquired brain tissue from a neuropathology archive. [11C]PiB PET was used to image amyloid deposition in 11 controls (median [range] age, 35 [24-60] years) and in 15 patients (median [range] age, 33 [21-50] years) between 1 and 361 days after a TBI. [3H]PiB autoradiography and immunocytochemistry for β-amyloid (Aβ) and β-amyloid precursor protein in brain tissue were obtained from separate cohorts of 16 patients (median [range] age, 46 [21-70] years) who died between 3 hours and 56 days after a TBI and 7 controls (median [range] age, 61 [29-71] years) who died of other causes.
Main Outcomes and Measures  We quantified the [11C]PiB distribution volume ratio and standardized uptake value ratio in PET images. The distribution volume ratio and the standardized uptake value ratio were measured in cortical gray matter, white matter, and multiple cortical and white matter regions of interest, as well as in striatal and thalamic regions of interest. We examined [3H]PiB binding and Aβ and β-amyloid precursor protein immunocytochemistry in autopsy-acquired brain tissue.
Results  Compared with the controls, the patients with TBI showed significantly increased [11C]PiB distribution volume ratios in cortical gray matter and the striatum (corrected P < .05 for both), but not in the thalamus or white matter. Increases in [11C]PiB distribution volume ratios in patients with TBI were seen across most cortical subregions, were replicated using comparisons of standardized uptake value ratios, and could not be accounted for by methodological confounders. Autoradiography revealed [3H]PiB binding in neocortical gray matter, in regions where amyloid deposition was demonstrated by immunocytochemistry; white matter showed Aβ and β-amyloid precursor protein by immunocytochemistry, but no [3H]PiB binding. No plaque-associated amyloid immunoreactivity or [3H]PiB binding was seen in cerebellar gray matter in autopsy-acquired tissue from either controls or patients with TBI, although 1 sample of cerebellar tissue from a patient with TBI showed amyloid angiopathy in meningeal vessels.
Conclusions and Relevance  [11C]PiB shows increased binding following TBI. The specificity of this binding is supported by neocortical [3H]PiB binding in regions of amyloid deposition in the postmortem tissue of patients with TBI. [11C]PiB PET could be valuable in imaging amyloid deposition following TBI.
There is increasing acceptance of epidemiological and pathophysiological links between traumatic brain injury (TBI) and Alzheimer disease (AD).13 β-Amyloid (Aβ) plaques, a hallmark of AD, are found in up to 30% of patients who die in the acute phase following TBI47; they appear within hours of injury and are present in all age groups. In contrast, in individuals dying of nonneurological causes, Aβ plaques tend to be confined to elderly individuals.5 At autopsy, Aβ plaques in patients with TBI are predominantly found in gray matter but have also been reported in white matter.8 The dominant Aβ species found in TBI-associated plaques and oligomers is Aβ42,7,9,10 which is the aggregation-prone species also found in AD. Autopsy studies conducted at varying intervals after TBI suggest that these deposits are cleared over a period of weeks following injury.11 Recent postmortem evidence suggests that, following TBI, the Aβ deposition associated with “normal” aging may be subsequently accelerated,12 but our inability to quantify amyloid binding in vivo limits a broader understanding of the temporal profile and outcome of amyloid deposition in TBI.
Positron emission tomography (PET) may provide one solution to this problem. Several carbon 11–labeled and fluorine 18–labeled PET ligands for amyloid imaging have been developed and used in AD.13 The most widely studied of these, Pittsburgh compound B (PiB),14 is widely validated as a marker of cerebral amyloid deposition. In individuals with AD, and in the general population, the relative distribution of Aβ as measured by carbon 11–labeled PiB ([11C]PiB) PET correlates well with neuropathology, with a predilection for high frontal, temporoparietal, and striatal binding and relatively low but still significant mesial temporal binding.13
However, documented amyloid deposition may be unassociated with [11C]PiB binding seen on PET scans,1517 or it may have distinct patterns of binding across the brain, depending on the genetic abnormality predisposing to amyloid deposition,18 suggesting molecular heterogeneity in amyloid species in relation to [11C]PiB binding. Therefore, before using serial [11C]PiB PET to examine amyloid deposition in patients with TBI, we need to be certain of the correspondence between [11C]PiB PET imaging and pathology. Furthermore, we have no idea of the time points following injury when changes in amyloid deposition might be best detected. Given these considerations, we have undertaken a cross-sectional pilot study of [11C]PiB PET for patients with moderate to severe TBI, imaged at a range of times after TBI. To validate our imaging findings, we also undertook a comparison of in vitro tritium-labeled PiB ([3H]PiB) binding against immunocytochemistry for Aβ in autopsy-acquired brain tissue obtained from a separate cohort of patients.

JAMA Neurology 2013