domenica 27 aprile 2014
Cognitive impairment (CI) is an exclusion criterion for the diagnosis of multiple system atrophy (MSA), according to the second consensus statement. This view was recently challenged by patients with pathologically confirmed MSA who were reported to have dementia. With an aim to investigate the pathological substrate of CI in MSA, quantitative assessment of the glial and neuronal cytoplasmic inclusions and semiquantitative assessment of neuronal loss in the cortical and limbic regions was performed. No differences in the severity of these MSA-related pathological findings were identified between nine MSA cases with CI and nine MSA cases with normal cognition. Alzheimer's-related pathological changes, cerebral amyloid angiopathy, and cerebrovascular disease did not differ between the two MSA groups. MSA-specific α-synuclein and secondary pathological conditions were not more severe in MSA cases with CI, suggesting that although CI may be intrinsic to the MSA disease process, further investigation into the pathological basis of cognitive impairment in MSA is warranted.
Movement Disorders 2014
Laryngeal dystonia is a movement disorder of the muscles within the larynx, which most commonly manifests as spasmodic dysphonia (SD). Rarer reported manifestations include dystonic respiratory stridor and dyscoordinate breathing. Laryngeal dystonia has been treated successfully with botulinum neurotoxin (BTX) injections since 1984. We reviewed prospectively collected data in a consecutive series of 193 patients with laryngeal dystonia who were seen at St. Vincent's Hospital between 1991 and 2011. Patient data were analyzed in Excel, R, and Prism. Laryngeal dystonia manifested as SD (92.7%), stridor (11.9%), dystonic cough (6.2%), dyscoordinate breathing (4.1%), paroxysmal hiccups (1.6%), and paroxysmal sneezing (1.6%). There were more women (68.4%) than men (31.6%), and the average age at onset was 47 years. A positive family history of dystonia was present in 16.1% of patients. A higher incidence of extra-laryngeal dystonia (ie, torticollis and blepharospasm) and concurrent manifestations of laryngeal dystonia were present in patients with dystonic cough, dyscoordinate breathing, paroxysmal sneezing, and hiccups than in other patients ( = 0.003 and < 0.0001, respectively). The average starting dose of BTX decreased from 2.3 to 0.5 units between 1991 and 2011. The median treatment rating was across all subgroups. Patients with adductor SD, stridor, extra-laryngeal dystonia and male patients had relatively better treatment outcomes. Technical failures were rare (1.1%). Dysphonia secondary to vocal cord paresis followed 38.7% of treatments. Laryngeal dystonia manifests predominantly as SD, but other manifestations include stridor, dyscoordinate breathing, paroxysmal cough, hiccups, and sneezing. BTX injections are very effective across all subgroups. Severe adverse events are rare.
Movement Disorders 2014
It was reported that the intron 6, + 1 del G (GT>TT) mutation of the ARHGEF28 gene generates a shortened protein that might be related to amyotrophic lateral sclerosis (ALS). We sequenced this mutation in 25 familial ALS (FALS), 357 sporadic ALS (SALS) patients, and 442 healthy control subjects. We found just two SALS patients exhibited the mutation so that the incidence of this mutation was 0.52% (2/382) of all the ALS patients. The clinical features of the mutation-positive patients were quite different from the case reported in a previous study. These characteristics differed in terms of gender, site of onset, cognitive function, and family history.
Amyotroph Lateral Scler Frontotemporal Degener. 2014
Detection of a novel frameshift mutation and regions with homozygosis within ARHGEF28 gene in familial amyotrophic lateral sclerosis.
Rho guanine nucleotide exchange factor (RGNEF) is a novel NFL mRNA destabilizing factor that forms neuronal cytoplasmic inclusions in spinal motor neurons in both sporadic (SALS) and familial (FALS) ALS patients. Given the observation of genetic mutations in a number of mRNA binding proteins associated with ALS, including TDP-43, FUS/TLS and mtSOD1, we analysed the ARHGEF28 gene (approx. 316 kb) that encodes for RGNEF in FALS cases to determine if mutations were present. We performed genomic sequencing, copy number variation analysis using TaqMan real-time PCR and spinal motor neuron immunohistochemistry using a novel RGNEF antibody. In this limited sample of FALS cases (n=7) we identified a heterozygous mutation that is predicted to generate a premature truncated gene product. We also observed extensive regions of homozygosity in the ARHGEF28 gene in two FALS patients. In conclusion, our findings of genetic alterations in theARHGEF28 gene in cases of FALS suggest that a more comprehensive genetic analysis would be warranted.
Amyotroph Lateral Scler Frontotemporal Degener. 2013
Sudden unexpected death in epilepsy (SUDEP) is cited as the cause of nearly 2,000 deaths per year in the USA alone, and accounts for as many as 15% of epilepsy-related deaths. Controversy prevails over the relative contributions of cardiac failure and respiratory arrest to SUDEP. Here, the authors discuss the mechanisms that cause cardiac, respiratory and arousal abnormalities during the ictal and postictal periods, and highlight possible preventive interventions that might reduce the risk of SUDEP.
Nature Reviews Neurology 2014
The aetiology of most epilepsies used to be regarded as unknown, but in the past few years, massively parallel gene-sequencing techniques and clinical genetic studies have revealed that many forms of epilepsy—including those formerly labelled as idiopathic or acquired—are likely to have a genetic basis. Increased understanding of the genetic architecture of epilepsies has important implications for genetic testing, treatment selection and counselling. Furthermore, understanding the genetic background of epilepsies can guide neurobiological research for novel therapies.
Nature Reviews Neurology 2014
Sexually dimorphic behaviors, qualitative or quantitative differences in behaviors between the sexes, result from the activity of a sexually differentiated nervous system. Sensory cues and sex hormones control the entire repertoire of sexually dimorphic behaviors, including those commonly thought to be charged with emotion such as courtship and aggression. Such overarching control mechanisms regulate distinct genes and neurons that in turn specify the display of these behaviors in a modular manner. How such modular control is transformed into cohesive internal states that correspond to sexually dimorphic behavior is poorly understood. We summarize current understanding of the neural circuit control of sexually dimorphic behaviors from several perspectives, including how neural circuits in general, and sexually dimorphic neurons in particular, can generate sexually dimorphic behaviors, and how molecular mechanisms and evolutionary constraints shape these behaviors. We propose that emergent themes such as the modular genetic and neural control of dimorphic behavior are broadly applicable to the neural control of other behaviors.
venerdì 25 aprile 2014
sabato 19 aprile 2014
Ataxia-telangiectasia is a recessive genetic disorder ( is the mutated gene) of childhood with severe motor impairments and whereas homozygotes manifest the disorder, heterozygotes are asymptomatic. Structural brain imaging and post-mortem studies in individuals with ataxia-telangiectasia have reported cerebellar atrophy; but abnormalities of motor control characteristic of extrapyramidal dysfunction suggest impairment of broader motor networks. Here, we investigated possible dysfunction in other brain areas in individuals with ataxia-telangiectasia and tested for brain changes in asymptomatic relatives to assess if heterozygocity affects brain function. We used positron emission tomography and 18F-fluorodeoxyglucose to measure brain glucose metabolism (quantified as µmol/100 g/min), which serves as a marker of brain function, in 10 adults with ataxia-telangiectasia, 19 non-affected adult relatives (12 siblings, seven parents) and 29 age-matched healthy controls. Statistical parametric mapping and region of interest analyses were used to compare individuals with ataxia-telangiectasia, asymptomatic relatives, and unrelated controls. We found that participants with ataxia-telangiectasia had lower metabolism in cerebellar hemispheres (14%, < 0.001), anterior vermis (40%, < 0.001) and fusiform gyrus (20%, < 0.001) compared with controls or siblings, and lower metabolism in hippocampus (12%, = 0.05) compared with controls, and showed significant intersubject variability (decreases in vermis ranged from 18% to 60%). Participants with ataxia-telangiectasia also had higher metabolism in globus pallidus (16%, = 0.05), which correlated negatively with motor performance. Asymptomatic relatives had lower metabolism in anterior vermis (12%; = 0.01) and hippocampus (19%; = 0.002) than controls. Our results indicate that, in addition to the expected decrease in cerebellar metabolism, participants with ataxia-telangiectasia had widespread changes in metabolic rates including hyperactivity in globus pallidus indicative of basal ganglia involvement. Changes in basal ganglia metabolism offer potential insight into targeting strategies for therapeutic deep brain stimulation. Our finding of decreased metabolism in vermis and hippocampus of asymptomatic relatives suggests that heterozygocity influences the function of these brain regions.
JAMA Neurology 2014
Reduced dendritic arborization and hyperexcitability of pyramidal neurons in a Scn1b-based model of Dravet syndrome
Epileptic encephalopathies, including Dravet syndrome, are severe treatment-resistant epilepsies with developmental regression. We examined a mouse model based on a human β1 sodium channel subunit () mutation. Homozygous mutant mice shared phenotypic features and pharmaco-sensitivity with Dravet syndrome. Patch-clamp analysis showed that mutant subicular and layer 2/3 pyramidal neurons had increased action potential firing rates, presumably as a consequence of their increased input resistance. These changes were not seen in L5 or CA1 pyramidal neurons. This raised the concept of a regional seizure mechanism that was supported by data showing increased spontaneous synaptic activity in the subiculum but not CA1. Importantly, no changes in firing or synaptic properties of gamma-aminobutyric acidergic interneurons from mutant mice were observed, which is in contrast with-based models of Dravet syndrome. Morphological analysis of subicular pyramidal neurons revealed reduced dendritic arborization. The antiepileptic drug retigabine, a K+ channel opener that reduces input resistance, dampened action potential firing and protected mutant mice from thermal seizures. These results suggest a novel mechanism of disease genesis in genetic epilepsy and demonstrate an effective mechanism-based treatment of the disease.
Diagnostic precision of PET imaging and functional MRI in disorders of consciousness: a clinical validation study
For this clinical validation study, we included patients referred to the University Hospital of Liège, Belgium, between January, 2008, and June, 2012, who were diagnosed by our unit with unresponsive wakefulness syndrome, locked-in syndrome, or minimally conscious state with traumatic or non-traumatic causes. We did repeated standardised clinical assessments with the Coma Recovery Scale—Revised (CRS—R), cerebral 18F-fluorodeoxyglucose (FDG) PET, and fMRI during mental activation tasks. We calculated the diagnostic accuracy of both imaging methods with CRS—R diagnosis as reference. We assessed outcome after 12 months with the Glasgow Outcome Scale—Extended.
We included 41 patients with unresponsive wakefulness syndrome, four with locked-in syndrome, and 81 in a minimally conscious state (48=traumatic, 78=non-traumatic; 110=chronic, 16=subacute). 18F-FDG PET had high sensitivity for identification of patients in a minimally conscious state (93%, 95% CI 85—98) and high congruence (85%, 77—90) with behavioural CRS—R scores. The active fMRI method was less sensitive at diagnosis of a minimally conscious state (45%, 30—61) and had lower overall congruence with behavioural scores (63%, 51—73) than PET imaging. 18F-FDG PET correctly predicted outcome in 75 of 102 patients (74%, 64—81), and fMRI in 36 of 65 patients (56%, 43—67). 13 of 42 (32%) of the behaviourally unresponsive patients (ie, diagnosed as unresponsive with CRS—R) showed brain activity compatible with (minimal) consciousness (ie, activity associated with consciousness, but diminished compared with fully conscious individuals) on at least one neuroimaging test; 69% of these (9 of 13) patients subsequently recovered consciousness.
Cerebral 18F-FDG PET could be used to complement bedside examinations and predict long-term recovery of patients with unresponsive wakefulness syndrome. Active fMRI might also be useful for differential diagnosis, but seems to be less accurate.
The Belgian National Funds for Scientific Research (FNRS), Fonds Léon Fredericq, the European Commission, the James McDonnell Foundation, the Mind Science Foundation, the French Speaking Community Concerted Research Action, the University of Copenhagen, and the University of Liège.
domenica 13 aprile 2014
Lambert–Eaton myasthenic syndrome (LEMS) is a pre-synaptic disorder of the neuromuscular and autonomic transmission mediated by antibodies to voltage-gated calcium channels at the motor nerve terminal. LEMS is a quite rare and probably under-diagnosed disease: the onset may be slow and clinical signs are typically fluctuating, thus adding to the delay in diagnosis. LEMS weakness typically involves lower and upper limbs and the proximal muscles are predominantly affected. A significant proportion of patients also have dysfunction of the autonomic nervous system that may include dry mouth, constipation, blurred vision, impaired sweating, and orthostatic hypotension. LEMS recognition is based on clinical, electrophysiological and immunological criteria. Nearly 50–60 % of patients with LEMS have an underlying tumour that, in almost all cases, is a small-cell lung cancer; the onset of neurological symptoms generally precedes tumour detection. A careful screening for the early detection of the possible associated cancer is a crucial step for optimal disease management. The Italian Working Group on Myasthenic Syndromes developed diagnostic and therapeutic algorithms that could serve in routine clinical practice as tools for a patient-tailored approach.
Neurological Sciences 2014