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Objectives The neural activity of the primary motor cortex is variably synchronised with contralateral peripheral electromyographic signals, which is thought to facilitate long-range communication through the motor system. Such corticomuscular coherence (CMC) is typically observed in the beta-band (15–30 Hz) range during steady force production. We aimed to measure pathological alteration to CMC resulting from ALS. Methods CMC was appraised during a forearm grip task in 17 ALS patients contrasted against age-matched healthy controls. An exploratory comparison with a group of asymptomatic ALS gene carriers and neuropathy disease mimics was also undertaken. Neural signals were acquired by whole-head magnetoencephalography and localised via structural MRI to the motor cortices. Results During light voluntary muscular contraction, beta-band CMC was significantly reduced in ALS patients compared to healthy controls. Propagation of motoric beta rhythms across the cortical hemispheres was also shown to be impaired in ALS patients. CMC was preserved in the asymptomatic gene carrier and did not distinguish ALS patients from neuropathy mimics. Conclusion Functional connectivity metrics reveal an ALS-related decrease in both corticomuscular and interhemispheric communication during bilateral grip force production. Significance MEG-derived beta oscillation coupling may be a potential biomarker of motor system dysfunction in ALS, against which to measure future therapeutic efficacy.

Rationale and Objectives T2-weighted MRI hyperintensity assessed visually in the corticospinal tract (CST) lacks sensitivity for a diagnosis of amyotrophic lateral sclerosis (ALS). We sought to explore a quantitative approach to FLAIR MRI intensity across a range of ALS phenotypes. Materials & Methods Thirty three classical ALS patients, 10 with a flail arm presentation, and 6 with primary lateral sclerosis underwent MRI at 3 Tesla. Comparisons of quantitative FLAIR intensity in the corticospinal tract (CST) and corpus callosum were made between 21 healthy controls and within patient phenotypic sub-groups, some of who were studied longitudinally. Results Mean FLAIR intensity was greater in patient groups. The cerebral peduncle intensity provided the strongest sub-group classification. FLAIR intensity increased longitudinally. The rate of change of FLAIR within CST correlated with rate of decline in executive function and ALS Functional Rating Score. Conclusion FLAIR MRI encodes quantifiable information of potential diagnostic, stratification and monitoring value.

Amyotrophic lateral sclerosis (ALS) is a fatal, progressive neurodegenerative disease resulting from a complex interplay between genetics and environment. Impairments in axonal transport have been identified in several ALS models, but in vivo evidence remains limited, thus the pathogenic importance of axonal transport remains to be fully resolved. We therefore analysed the in vivo dynamics of retrogradely transported, neurotrophin-containing signalling endosomes in nerve axons of two new ALS mouse models with mutations in the RNA processing genes TARDBP and FUS. TDP-43M337V mice, which show neuromuscular pathology without motor neuron loss, displayed perturbations in axonal transport manifesting between 1.5 and 3 months and preceding symptom onset. Contrastingly, despite 20% motor neuron loss, transport remained largely unaffected in FusΔ14/+ mice. Axonal transport deficiencies are therefore not a common feature to all ALS-linked genes, indicating that there are mechanistic distinctions in the pathogenesis of ALS caused by mutations in different RNA processing genes.

Objective The progressively disabling and terminal nature of ALS/MND imposes major coping demands on patients. We wished to improve the psychometric properties of our previously published MND-Coping Scale, so that parametric analyses were valid, and to make it simpler for patients to complete and clinicians to score. Methods After a new qualitative analysis of 26 patients with ALS/MND, the draft Coping Index-ALS (CI-ALS) was administered to 465 additional patients, alongside COPE-60, General Perceived Self Efficacy scale, and WHOQOL-BREF. Validity of the CI-ALS was assessed using the Rasch model. External validity was checked against comparator measures. Results Thirteen centres contributed 465 patients, mean age 64.9 years (SD 10.8), mean disease duration 28.4 months (SD 37.5). The CI-ALS-Self and CI-ALS-Others both satisfied Rasch model expectations and showed invariance across age, gender, marital status and type of onset. Expected correlations were observed with comparator scales. A nomogram is available to convert the raw scores to interval level measures suitable for parametric analysis. Conclusions Coping abilities in ALS/MND can now be measured using a simple 21 item self-report measure, offering two subscales with a focus of ‘coping by self ’ and ‘coping with others’. This allows clinicians to identify individuals with poor coping and facilitates research on interventions that may improve coping skills.

TDP-43 pathology is a key feature of amyotrophic lateral sclerosis (ALS), but the mechanisms linking TDP-43 to altered cellular function and neurodegeneration remain unclear. We have recently described a mouse model in which human wild-type or mutant TDP-43 are expressed at low levels and where altered stress granule formation is a robust phenotype of TDP-43M337V/− expressing cells. In the present study we use this model to investigate the functional connectivity of human TDP-43 in primary motor neurons under resting conditions and in response to oxidative stress. The interactome of human TDP-43WT or TDP-43M337V was compared by mass spectrometry, and gene ontology enrichment analysis identified pathways dysregulated by the M337V mutation. We found that under normal conditions the interactome of human TDP-43WT was enriched for proteins involved in transcription, translation and poly(A)-RNA binding. In response to oxidative stress, TDP-43WT recruits proteins of the endoplasmic reticulum and endosomal-extracellular transport pathways, interactions which are reduced in the presence of the M337V mutation. Specifically, TDP-43M337V impaired protein-protein interactions involved in stress granule formation including reduced binding to the translation initiation factors Poly(A)-binding protein and Eif4a1 and the endoplasmic reticulum chaperone Grp78. The M337V mutation also affected interactions involved in endosomal-extracellular transport and this this was associated with reduced extracellular vesicle secretion in primary motor neurons from TDP-43M337V/− mice and in human iPSCs-derived motor neurons. Taken together, our analysis highlights a TDP-43 interaction network in motor neurons and demonstrates that an ALS associated mutation may alter the interactome to drive aberrant pathways involved in the pathogenesis of ALS.

Summary Amyotrophic lateral sclerosis (ALS) is a fatal, progressive neurodegenerative disease resulting from a complex interplay between genetics and environment. Impairments in axonal transport have been identified in several ALS models, but in vivo evidence remains limited, thus their pathogenetic importance remains to be fully resolved. We therefore analyzed the in vivo dynamics of retrogradely transported, neurotrophin-containing signaling endosomes in nerve axons of two ALS mouse models with mutations in the RNA processing genes TARDBP and FUS. TDP-43M337V mice, which show neuromuscular pathology without motor neuron loss, display axonal transport perturbations manifesting between 1.5 and 3 months and preceding symptom onset. Contrastingly, despite 20% motor neuron loss, transport remained largely unaffected in FusΔ14/+ mice. Deficiencies in retrograde axonal transport of signaling endosomes are therefore not shared by all ALS-linked genes, indicating that there are mechanistic distinctions in the pathogenesis of ALS caused by mutations in different RNA processing genes., Graphical Abstract, Highlights • Mutant TDP-43 mice display in vivo defects in signaling endosome axonal transport • Despite motor neuron loss, mutant FUS mice display no such deficiency • Axonal transport disruption is thus not common to all ALS mouse models, Sleigh et al. address the importance of disturbances in axonal transport in two mouse models for ALS. They find that deficiencies in the in vivo axonal delivery of target tissue-derived survival factors are not a common feature of all ALS mouse models, suggesting mechanistic distinctions in different ALS-linked genes.

The transactive response DNA binding protein (TDP-43) is a major component of the characteristic neuronal cytoplasmic inclusions seen in amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Furthermore, pathogenic mutations in the gene encoding TDP-43, TARDBP, are found in sporadic and familial ALS cases. To study the molecular mechanisms of cellular toxicity due to TDP-43 mutations we generated a novel in vitro cellular model using a fluorescently tagged human genomic TARDBP locus carrying one of two ALS-associated mutations, A382T or M337V, which were used to generate site-specific bacterial artificial chromosome (BAC) human stable cell lines and BAC transgenic mice. In cell lines and primary motor neurons in culture, TDP-M337V mislocalized to the cytoplasm more frequently than wild-type TDP (wt-TDP) and TDP-A382T, an effect potentiated by oxidative stress. Expression of mutant TDP-M337V correlated with increased apoptosis detected by cleaved caspase-3 staining. Cells expressing mislocalized TDP-M337V spontaneously developed cytoplasmic aggregates, while for TDP-A382T aggregates were only revealed after endoplasmic reticulum (ER) stress induced by the calcium-modifying drug thapsigargin. Lowering Ca(2+) concentration in the ER of wt-TDP cells partially recapitulated the effect of pathogenic mutations by increasing TDP-43 cytoplasmic mislocalization, suggesting Ca(2+) dysregulation as a potential mediator of pathology through alterations in Bcl-2 protein levels. Ca(2+) signaling from the ER was impaired in immortalized cells and primary neurons carrying TDP-43 mutations, with a 50% reduction in the levels of luminal ER Ca(2+) stores content and delayed Ca(2+) release compared with cells carrying wt-TDP. The deficits in Ca(2+) release in human cells correlated with the upregulation of Bcl-2 and siRNA-mediated knockdown of Bcl-2 restored the amplitude of Ca(2+) oscillations in TDP-M337V cells. These results suggest that TDP-43 pathogenic mutations elicit cytoplasmic mislocalization of TDP-43 and Bcl-2 mediated ER Ca(2+) signaling dysregulation.

The pathogenesis of ALS is not fully understood but, as an overwhelmingly sporadic disorder, it is likely to result from a complex mixture of polygenic and environmental risk factors operating in the context of an ageing nervous system. Physical trauma, in particular head injury, has been variably associated with both Alzheimer's and Parkinson's disease, and largely discounted in relation to multiple sclerosis. Several case-control studies in ALS have reported an association with physical trauma or head injury, but such studies are greatly limited by recall bias. The Oxford Record Linkage Study (ORLS) includes brief statistical abstracts of records of all hospital admissions, including day cases, and all deaths for a defined region of UK National Health Service hospitals. We used ORLS spanning a 36year period to study the relationship between recorded head, upper and lower limb trauma both before and after a diagnosis of ALS. Overall the adjusted rate ratio for ALS after head injury, compared with a control group, was 1.5 (95% confidence interval 1.1-2.1); but this elevation of risk was only found within the first year after injury, and we speculate that this is most likely to be a consequence of incipient ALS causing a tendency to fall. We conclude that there is no association between antecedent injury requiring hospitalisation, and the later development of ALS. The high risk of head injury observed in the immediate post-diagnosis period may be amenable to primary prevention.

Amyotrophic lateral sclerosis (ALS; motor neuron disease) is a relentlessly progressive disorder. After half a century of trials, only one drug with modest disease-modifying potency--riluzole--has been developed. The diagnosis of this disorder is still clinical and there is a pronounced delay between the onset of symptoms and diagnosis, possibly beyond the therapeutic window. Bedside quantification of the involvement of the corticospinal tract and extramotor areas is inadequate and functional rating scales, forced vital capacity, and patient survival have been the measures of therapeutic response so far. Potential biomarkers that are sensitive to the progression of disease, which might enhance the diagnostic algorithm and provide new drug targets, are now being identified from analysis of the blood and cerebrospinal fluid, as well as from neuroimaging and neurophysiology studies. In combination, these biomarkers might be sensitive to early therapeutic effects and would reduce our reliance on animal models, which have uncertain relevance to sporadic ALS in human beings. Such biomarkers might also resolve complexities of phenotypic heterogeneity in clinical trials. In this Review, we discuss the development of biomarkers in ALS and consider potential future directions for research.

Charcot-Marie-Tooth disease type 2D (CMT2D) is a peripheral nerve disorder caused by dominant, toxic, gain-of-function mutations in the widely expressed, housekeeping gene, GARS The mechanisms underlying selective nerve pathology in CMT2D remain unresolved, as does the cause of the mild-to-moderate sensory involvement that distinguishes CMT2D from the allelic disorder distal spinal muscular atrophy type V. To elucidate the mechanism responsible for the underlying afferent nerve pathology, we examined the sensory nervous system of CMT2D mice. We show that the equilibrium between functional subtypes of sensory neuron in dorsal root ganglia is distorted by Gars mutations, leading to sensory defects in peripheral tissues and correlating with overall disease severity. CMT2D mice display changes in sensory behavior concordant with the afferent imbalance, which is present at birth and nonprogressive, indicating that sensory neuron identity is prenatally perturbed and that a critical developmental insult is key to the afferent pathology. Through in vitro experiments, mutant, but not wild-type, GlyRS was shown to aberrantly interact with the Trk receptors and cause misactivation of Trk signaling, which is essential for sensory neuron differentiation and development. Together, this work suggests that both neurodevelopmental and neurodegenerative mechanisms contribute to CMT2D pathogenesis, and thus has profound implications for the timing of future therapeutic treatments.

An 18-year-old-man was referred to the Neurology Department complaining of headache and double vision. The headache was exquisitely sensitive to postural changes, being completely abolished by lying at. Neurological examination revealed an isolated right sixth nerve palsy. Some 5 weeks previously he had been seen in the Emergency Department of his local hospital after being assaulted with a screwdriver, leading to a penetrating injury of the back at the level of the ninth thoracic vertebra. A plain X-ray was performed and the attending doctor removed the screwdriver. Three days after this injury he represented to the same hospital complaining of sudden onset of headache and vomiting. A diagnosis of migraine was made and he was discharged the next day. The headache persisted and 10 days later he represented because of double vision, mu‚ed hearing, mild neck sti€ness and photophobia, at which time the neurological referral was made. Computed tomography (CT) of the brain on this occasion was normal except for a dilated straight sinus (Fig. 1). A lumbar puncture was not performed. There was no signi®cant past medical history. Brain MRI was performed 4 weeks after injury. The T2-weighted axial images showed dilatation of the dural venous sinuses (Fig. 2a) and the proton density-weighted axial images revealed small subdural and subtentorial collections which were of a higher signal than CSF (Fig. 2b). A sagittal T1-weighted image showed the cerebellar tonsils at the foramen magnum, and post gadolinium-DTPA enhanced coronal T1-weighted images showed homogeneous dural enhancement (Fig. 2c). A diagnosis of probable intracranial hypotension was made and, due to the penetrating nature of the trauma, MRI of the spine was performed. A marker was placed at the site of the skin wound. Sagittal T2-weighted fat-saturated images revealed bright signal posterior to the thecal sac and no evidence of cord injury (Fig. 3a). Axial T2-weighted fat-saturated images showed the spinal cord surrounded by a reduced volume of CSF and an extradural uid collection, the same signal as CSF (Fig. 3b). From this imaging it was concluded that there was a traumatic dural CSF leak causing symptomatic intracranial hypotension. Since the patient had not improved with conservative management, an autologous epidural blood patch was performed, at the site of penetrating injury, and his symptoms resolved completely.

Spinal muscular atrophy (SMA) is caused by a drastic reduction in the ubiquitously expressed SMN protein, which is critical for the correct assembly of the snRNP complexes required for RNA splicing. However, it is unclear why loss of SMN and altered snRNP assembly only seem to affect motor neurons. Reporting in this issue, Zhang et al. (2008) challenge prior assumptions about the housekeeping function of SMN and demonstrate that loss of SMN leads to highly tissue-specific effects on splicing.

Mitogen-activated protein kinase phosphatases (MKPs) play a central role in a variety of signaling pathways. We recently described a novel murine MKP, M3/6, which is uniquely specific for c-Jun N-terminal kinase/stress-activated protein kinase and p38 kinase. Here we report the localization of the human orthologue of this gene, HB5, to within 150 kb of H19 on human chromosome 11p15.5. The gene consists of six exons. Two of the introns in HB5 are not found in other genes of this family, suggesting an evolutionary split between MKPs displaying specificity toward different MAP kinases. An intronless pseudogene is present on chromosome 10q11.2. Although 11p15.5 is an imprinted region, HB5 is almost entirely unmethylated on both alleles in lymphocytes. Chromosome 11p15 has been implicated in the development of a number of tumor types, including lung, a tissue known to express this gene. Loss of heterozygosity was found in one of eight informative lung tumors studied.

Autosomal recessive proximal spinal muscular atrophy (SMA) is a disease of motor neuron death and a common cause of morbidity in childhood. It has been mapped to 5q13 and shown to be associated with deletions in a gene which has been called the survival motor neuron (SMN) gene. SMN exists in two copies in 5q13 and deletions in exon 7 and 8 of the telomeric copy (SMN tel ) occur in over 90% of patients regardless of disease severity. In contrast, deletion of exon 7 and 8 of the centromeric copy of SMN is present in 3–5% of the normal population. In a minority of patients, exon 7 but not exon 8 of SMN tel appears deleted. The purpose of this study was to analyse this latter type of deletion in more detail. In all patients where there was absence of PCR amplification of exon 7 but not exon 8 of SMN tel this was found to be due to replacement with the homologous copy of SMN cen by a possible gene conversion event. This type of mutation occurred in all grades of severity of SMA.

A hexanucleotide repeat expansion mutation in the C9orf72 locus is the commonest genetic cause of amyotrophic lateral sclerosis and frontotemporal dementia (C9ALS/FTD). Currently, the biological function of C9orf72 remains unknown. However, bioinformatic analysis has revealed that the C9orf72 gene product has a differentially expressed in normal and neoplasia (DENN)-like domain and might regulate membrane trafficking as a Rab-GTPase GDP/GTP exchange factor. Here, using comprehensive GST-Rab pulldown analysis, we show that C9orf72 physically interacts with the Rab29 GTPase (also known as Rab7L1), suggesting that C9orf72 is a Rab29 effector. Further, we show that loss of the C9orf72/Rab29 interaction leads to dramatically reduced trafficking of extracellular vesicles (EVs), impaired intracellular trans-Golgi trafficking, and a consequent deficiency of autophagy in fibroblasts and iPSC-derived neurons from patients with C9ALS/FTD. Both overexpression of C9orf72 and antisense oligonucleotides targeting repeat-containing C9orf72 transcripts to upregulate normal variant 1 transcript levels are able independently to rescue the defective EV, trans-Golgi vesicle trafficking and basal autophagy phenotype. Our findings identify C9orf72 haploinsufficiency as a major contributing factor in ALS/FTD neurodegenerative disorders and directly link ALS/FTD to EV biogenesis. Furthermore, we demonstrate that this novel ALS/FTD pathogenic mechanism can be rescued by an antisense-based intervention.

Background Novel biomarker discovery and validation are essential to the development and appraisal of emerging therapies for the devastating cerebral neurodegenerative disorder motor neuron disease (MND), the commonest phenotype of which is amyotrophic lateral sclerosis (ALS). MND pathology (and strong genetic risk of MND prior to symptoms) was hypothesised to be manifested by changes in movement-related cortical neuronal β-oscillations. Methods We used magnetoencephalography (MEG) to investigate both symptomatic patients and asymptomatic mutation carriers at risk of developing ALS. MEG data were acquired during a visually cued lateralised motor preparation task that included infrequent movement inhibition trials. Data from 11 patients with ALS, ten with the upper motor neuron-only phenotype primary lateral sclerosis (PLS), and 12 asymptomatic mutation carriers were age-matched against healthy controls. Source-space MEG analysis used a combination of functionally defined voxels of interest and whole brain data to measure β-power before, during, and after movement execution or inhibition. Findings Patients with PLS were slower to respond to targets relative to controls (663 ms [SD 189] vs 440 [124], p=0·008), but the task was otherwise comparably performed across groups. Source reconstructed MEG data revealed excessive β-desynchronisation relative to controls in the motor cortices of both patients with ALS (p=0·012) and in asymptomatic mutation carriers (p=0·043). In only those patients with PLS, β-desynchronisation was inadequately lateralised to the contralateral motor cortex during response preparation. Transition to β-rebound was slowed in patients with ALS relative to controls (p=0·028). During successfully performed inhibition trials asymptomatic mutation carrier (p=0·046) groups demonstrated reduced inhibitory β-power relative to controls immediately before their expected response time to GO trials. Interpretation MEG is sensitive to cortical dysfunction in MND through changes in neural β-oscillations related to motor pathology. These abnormalities differ by phenotype, yet may be detectable before the development of overt symptoms in those at genetic risk. Funding Wellcome Trust, Medical Research Council.