Motor Neuron Disease/amyotrophic Lateral Sclerosis Research Articles

Targeting Sigma Receptors for the Treatment of Neurodegenerative and Neurodevelopmental Disorders.

The sigma-1 receptor is a 223 amino acid-long protein with a recently identified structure. The sigma-2 receptor is a genetically unrelated protein with a similarly shaped binding pocket and acts to influence cellular activities similar to the sigma-1 receptor. Both proteins are highly expressed in neuronal tissues. As such, they have become targets for treating neurological diseases, including Alzheimer's disease (AD), Huntington's disease (HD), Parkinson's disease (PD), multiple sclerosis (MS), Rett syndrome (RS), developmental and epileptic encephalopathies (DEE), and motor neuron disease/amyotrophic lateral sclerosis (MND/ALS). In recent years, there have been many pre-clinical and clinical studies of sigma receptor (1 and 2) ligands for treating neurological disease. Drugs such as blarcamesine, dextromethorphan and pridopidine, which have sigma-1 receptor activity as part of their pharmacological profile, are effective in treating multiple aspects of several neurological diseases. Furthermore, several sigma-2 receptor ligands are under investigation, including CT1812, rivastigmine and SAS0132. This review aims to provide a current and up-to-date analysis of the current clinical and pre-clinical data of drugs with sigma receptor activities for treating neurological disease.

Analysis of brain and spinal MRI measures in a common domain to investigate directional neurodegeneration in motor neuron disease

BackgroundMagnetic resonance imaging (MRI) of the brain and cervical spinal cord is often performed in diagnostic evaluation of suspected motor neuron disease/amyotrophic lateral sclerosis (MND/ALS). Analysis of MRI-derived tissue damage metrics in a common domain facilitates group-level inferences on pathophysiology. This approach was applied to address competing hypotheses of directionality of neurodegeneration, whether anterograde, cranio-caudal dying-forward from precentral gyrus or retrograde, dying-back.MethodsIn this cross-sectional study, MRI was performed on 75 MND patients and 13 healthy controls. Precentral gyral thickness was estimated from volumetric T1-weighted images using FreeSurfer, corticospinal tract fractional anisotropy (FA) from diffusion tensor imaging using FSL, and cross-sectional cervical cord area between C1-C8 levels using Spinal Cord Toolbox. To analyse these multimodal data within a common domain, individual parameter estimates representing tissue damage at each corticospinal tract level were first converted to z-scores, referenced to healthy control norms. Mixed-effects linear regression models were then fitted to these z-scores, with gradients hypothesised to represent directionality of neurodegeneration.ResultsAt group-level, z-scores did not differ significantly between precentral gyral and intracranial corticospinal tract tissue damage estimates (regression coefficient − 0.24, [95% CI − 0.62, 0.14], p = 0.222), but step-changes were evident between intracranial corticospinal tract and C1 (1.14, [95% CI 0.74, 1.53], p < 0.001), and between C5 and C6 cord levels (0.98, [95% CI 0.58, 1.38], p < 0.001).DiscussionAnalysis of brain and cervical spinal MRI data in a common domain enabled investigation of pathophysiological hypotheses in vivo. A cranio-caudal step-change in MND patients was observed, and requires further investigation in larger cohorts.

A Novel Genetic Marker for the C9orf72 Repeat Expansion in the Finnish Population.

C9orf72 repeat expansion (C9exp) is the most common genetic cause underlying frontotemporal lobar degeneration (FTLD) and amyotrophic lateral sclerosis (ALS). However, detection of the C9exp requires elaborative methods. Identification of C9exp carriers from genotyped cohorts could be facilitated by using single nucleotide polymorphisms (SNPs) as markers for the C9exp. We elucidated the potential of the previously described Finnish risk haplotype, defined by the SNP rs3849942, to identify potential C9exp carriers among 218,792 Finns using the FinnGen database. The haplotype approach was first tested in an idiopathic normal pressure hydrocephalus (iNPH) patient cohort (European Alzheimer's Disease DNA BioBank) containing C9exp carriers by comparing intermediate (15-30) and full-length (> 60 repeats) C9exp carriers (n = 41) to C9exp negative patients (< 15 repeats, n = 801). In this analysis, rs3849942 was associated with carriership of C9exp (OR 8.44, p < 2×10-15), while the strongest association was found with rs139185008 (OR 39.4, p < 5×10-18). Unbiased analysis of rs139185008 in FinnGen showed the strongest association with FTLD (OR 4.38, 3×10-15) and motor neuron disease ALS (OR 5.19, 3×10-21). rs139185008 was the top SNP in all diseases (iNPH, FTLD, ALS), and further showed a strong association with ALS in the UK Biobank (p = 9.0×10-8). Our findings suggest that rs139185008 is a useful marker to identify potential C9exp carriers in the genotyped cohorts and biobanks originating from Finland.

Incorporating self-reported questions for telemonitoring to optimize care of patients with MND on noninvasive ventilation (MND OptNIVent)

Objective: Previous studies suggest a positive impact of telehealth in the care of people with motor neuron disease/amyotrophic lateral sclerosis (MND/ALS). This study reports the development of self-reported questions for telemonitoring, using a tablet-based device Careportal®, in the care of patients with MND on noninvasive ventilation (NIV) and its initial impact. Methods: The study consisted of a question development phase and an evaluation phase of the use of Careportal®. The development phase employed a modified Delphi process. The evaluation phase involved a 24-week pilot study with 13 patients (median age = 66; median illness duration = 14 m), who were using NIV. The participants completed overnight oximetry and self-report questions via Careportal® each week, generating interventions where required. Patient–ventilator interaction (PVI) data were monitored and the revised ALS functional rating scale (ALSFRS-R) was completed. Results: Telemonitoring encompassing the newly developed 26-item symptom questions showed good feasibility and validity. During the evaluation phase, 61 interventions were made for 10 patients, including seven patients who had routine clinic appointments during the trial to optimize care. ALSFRS-R showed significant illness deteriorations. Blood oxygen saturation (SpO2) levels were maintained, time ventilated and inspiratory pressures increased during the trial. Conclusions: The MND OptNIVent question set together with weekly ventilator and oximetry monitoring facilitated the maintenance of ventilation and SpO2 levels despite illness progression. The use of the question set, and devices, such as Careportal®, facilitate care and may further enable a single point of contact for patients from which clinicians may offer proactive interventions to optimize care.

Imaging denervation in motor neuron disease for future clinical trials: a longitudinal cohort study

A key area-of-need in motor neuron disease/amyotrophic lateral sclerosis (MND/ALS) translational research is a tool to objectively track disease progression over short timescales, to reduce duration and cost of clinical trials. Previous studies have focused on the central nervous system.

Lower motor neuron dysfunction in ALS.

In the motor system there is a complex interplay between cortical structures and spinal cord lower motor neurons (LMN). In this system both inhibitory and excitatory neurons have relevant roles. LMN loss is a marker of motor neuron disease/amyotrophic lateral sclerosis (MND/ALS). Conventional needle electromyography (EMG) does not allow LMN loss to be quantified. Measurement of compound muscle action potential (CMAP) amplitude or area, and the neurophysiological index, provide a surrogate estimate of the number of functional motor units. Increased motor neuronal excitability is a neurophysiological marker of ALS in the context of a suspected clinical and electrophysiological diagnosis. In the LMN system, fasciculation potentials (FPs) are the earliest changes observed in affected muscles, a feature of LMN hyperexcitability. Reinnervation is best investigated by needle EMG although other methods can be explored. Moreover needle EMG give information about the temporal profile of the reinnervation process, important ancillary data. Quantitative motor unit potential analysis is a valuable method of evaluating reinnervation. The importance of FPs has been recognized in the Awaji criteria for the electrodiagnosis of ALS, criteria that are a sensitive adjunct to the revised El Escorial criteria. Finally, functionality of LMN's, and perhaps excitability studies in motor nerves, aids understanding of the disease process, allowing measurement of potential treatment effects in clinical trials. Other investigational techniques, such as electrical impedance myography, muscle and nerve ultrasound, and spinal cord imaging methods may prove useful in future.

Sialorrhoea: How to Manage a Frequent Complication of Motor Neuron Disease

Sialorrhoea, the unintentional loss of saliva through the mouth, is the frequent complication of neurological disorders affecting strength or coordination of oropharyngeal muscles, such as motor neuron disease/amyotrophic lateral sclerosis (MND/ALS) or Parkinson’s disease. Sialorrhoea might affect up to 42% of ALS patients, with almost half of them having poorly managed symptoms. Sialorrhoea can impair patients’ social life, while dermatological complications, such as skin rashes, may arise due to constant exposure to moisture. Moreover, the excess mouth-retained saliva in ALS patients may lead to serious complications, such as choking, which causes anxiety, and aspiration with the consequent pneumonia. The inclusion of a sialorrhoea-related item in the ALS functional rating scale testifies both the incidence and importance of sialorrhoea during the ALS clinical course. Because of the progressive nature of ALS, presence and severity of sialorrhoea should be assessed at every visit and, when present, active treatment pursued. Available treatments include behavioural therapy, i.e. techniques to enhance periodic swallowing of saliva, systemic or local anticholinergic medications, botulinum toxin injection, electron beam irradiation, and surgical techniques. This review paper briefly describes the available options with related side-effects and current guideline recommendations for managing sialorrhoea in ALS patients.

12q24 locus association with type 1 diabetes: SH2B3 or ATXN2?

Genetic linkage analyses, genome-wide association studies of single nucleotide polymorphisms, copy number variation surveys, and mutation screenings found the human chromosomal 12q24 locus, with the genes SH2B3 and ATXN2 in its core, to be associated with an exceptionally wide spectrum of disease susceptibilities. Hematopoietic traits of red and white blood cells (like erythrocytosis and myeloproliferative disease), autoimmune disorders (like type 1 diabetes, coeliac disease, juvenile idiopathic arthritis, rheumatoid arthritis, thrombotic antiphospholipid syndrome, lupus erythematosus, multiple sclerosis, hypothyroidism and vitiligo), also vascular pathology (like kidney glomerular filtration rate deficits, serum urate levels, plasma beta-2-microglobulin levels, retinal microcirculation problems, diastolic and systolic blood pressure and hypertension, cardiovascular infarction), furthermore obesity, neurodegenerative conditions (like the polyglutamine-expansion disorder spinocerebellar ataxia type 2, Parkinson's disease, the motor-neuron disease amyotrophic lateral sclerosis, and progressive supranuclear palsy), and finally longevity were reported. Now it is important to clarify, in which ways the loss or gain of function of the locally encoded proteins SH2B3/LNK and ataxin-2, respectively, contribute to these polygenic health problems. SH2B3/LNK is known to repress the JAK2/ABL1 dependent proliferation of white blood cells. Its null mutations in human and mouse are triggers of autoimmune traits and leukemia (acute lymphoblastic leukemia or chronic myeloid leukemia-like), while missense mutations were found in erythrocytosis-1 patients. Ataxin-2 is known to act on RNA-processing and trophic receptor internalization. While its polyglutamine-expansion mediated gain-of-function causes neuronal atrophy in human and mouse, its deletion leads to obesity and insulin resistance in mice. Thus, it is conceivable that the polygenic pathogenesis of type 1 diabetes is enhanced by an SH2B3-dysregulation-mediated predisposition to autoimmune diseases that conspires with an ATXN2-deficiency-mediated predisposition to lipid and glucose metabolism pathology.

Mechanisms defining the electrotonic potential abnormalities in simulated amyotrophic lateral sclerosis

Electrotonic potentials allow the accommodative processes to polarizing stimuli to be assessed. Electrotonic potential transients in response to applied polarizing stimuli are caused by the kinetics of underlying axonal conductances. Here, we study these transients using our multi-layered model of the human motor nerve, in three simulated cases of the motor neuron disease amyotrophic lateral sclerosis (ALS): ALS1, ALS2 and ALS3 are three consecutively greater degrees of uniform axonal dysfunctions along the human motor nerve fibre. The results show that the responses in the ALS1 case are quite similar to the normal case. In contrast, in the ALS2 and ALS3 cases, long-lasting (100 ms) subthreshold depolarizing stimuli activate the classical "transient" Na(+) channels in the nodal and in the internodal axolemma beneath the myelin sheath; this leads to action potential generation during the early parts of the electrotonic responses in all compartments along the fibre length. The results also show that the electrotonic potentials in response to long-lasting (100 ms) subthreshold hyperpolarizing stimuli in the ALS1 and ALS2 cases are quiet similar to those of the normal case. However, the current kinetics in the ALS3 case differs from the normal case after the termination of the long-lasting hyperpolarizing stimuli. In the most abnormal ALS3 case, the activation of the Na(+) channels in the nodal and in the internodal axolemma leads to repetitive action potential generation in the late parts (100-200 ms) of the hyperpolarizing electrotonic responses. The results show that the repetitive firing, due to the progressively increased nodal and internodal ion channel dysfunction, are consistent with the loss of functional potassium channels involving both the fast and the slow potassium channel types. The results confirm that the electrotonic potentials in the three simulated ALS cases are specific indicators for the motor neuron disease ALS. The mechanisms underlying the simulated ALS are also discussed.

An MND/ALS phenotype associated with C9orf72 repeat expansion: Abundant p62‐positive, TDP‐43‐negative inclusions in cerebral cortex, hippocampus and cerebellum but without associated cognitive decline

The transactive response DNA binding protein (TDP-43) proteinopathies describe a clinico-pathological spectrum of multi-system neurodegeneration that spans motor neuron disease/amyotrophic lateral sclerosis (MND/ALS) and frontotemporal lobar degeneration (FTLD). We have identified four male patients who presented with the clinical features of a pure MND/ALS phenotype (without dementia) but who had distinctive cortical and cerebellar pathology that was different from other TDP-43 proteinopathies. All patients initially presented with weakness of limbs and respiratory muscles and had a family history of MND/ALS. None had clinically identified cognitive decline or dementia during life and they died between 11 and 32 months after symptom onset. Neuropathological investigation revealed lower motor neuron involvement with TDP-43-positive inclusions typical of MND/ALS. In contrast, the cerebral pathology was atypical, with abundant star-shaped p62-immunoreactive neuronal cytoplasmic inclusions in the cerebral cortex, basal ganglia and hippocampus, while TDP-43-positive inclusions were sparse. This pattern was also seen in the cerebellum where p62-positive, TDP-43-negative inclusions were frequent in granular cells. Western blots of cortical lysates, in contrast to those of sporadic MND/ALS and FTLD-TDP, showed high p62 levels and low TDP-43 levels with no high molecular weight smearing. MND/ALS-associated SOD1, FUS and TARDBP gene mutations were excluded; however, further investigations revealed that all four of the cases did show a repeat expansion of C9orf72, the recently reported cause of chromosome 9-linked MND/ALS and FTLD. We conclude that these chromosome 9-linked MND/ALS cases represent a pathological sub-group with abundant p62 pathology in the cerebral cortex, hippocampus and cerebellum but with no significant associated cognitive decline.

P62 positive, TDP-43 negative, neuronal cytoplasmic and intranuclear inclusions in the cerebellum and hippocampus define the pathology of C9orf72-linked FTLD and MND/ALS

Neuronal cytoplasmic inclusions (NCIs) containing phosphorylated TDP-43 (p-TDP-43) are the pathological hallmarks of motor neuron disease/amyotrophic lateral sclerosis (MND/ALS) and FTLD-TDP. The vast majority of NCIs in the brain and spinal cord also label for ubiquitin and p62, however, we have previously reported a subset of TDP-43 proteinopathy patients who have unusual and abundant p62 positive, TDP-43 negative inclusions in the cerebellum and hippocampus. Here we sought to determine whether these cases carry the hexanucleotide repeat expansion in C9orf72. Repeat primer PCR was performed in 36 MND/ALS, FTLD-MND/ALS and FTLD-TDP cases and four controls. Fourteen individuals with the repeat expansion were detected. In all the 14 expansion mutation cases there were abundant globular and star-shaped p62 positive NCIs in the pyramidal cell layer of the hippocampus, the vast majority of which were p-TDP-43 negative. p62 positive NCIs were also abundant in the cerebellar granular and molecular layers in all cases and in Purkinje cells in 12/14 cases but they were only positive for p-TDP-43 in the granular layer of one case. Abundant p62 positive, p-TDP-43 negative neuronal intranuclear inclusions (NIIs) were seen in 12/14 cases in the pyramidal cell layer of the hippocampus and in 6/14 cases in the cerebellar granular layer. This unusual combination of inclusions appears pathognomonic for C9orf72 repeat expansion positive MND/ALS and FTLD-TDP which we believe form a pathologically distinct subset of TDP-43 proteinopathies. Our results suggest that proteins other than TDP-43 are binding p62 and aggregating in response to the mutation which may play a mechanistic role in neurodegeneration.

Emotional Lability in MND: Relationship to cognition and psychopathology and impact on caregivers

Emotional Lability (EL) is a well recognized symptom of cortico-bulbar pathway dysfunction in Motor Neuron Disease/Amyotrophic Lateral Sclerosis (MND/ALS), and is reported to occur in 19-49% of patients. The Emotional Lability Questionnaire (ELQ), is specifically designed to detect EL as reported by MND patients and as observed by their carers. The aims of this study were to 1) validate the Italian version of the ELQ; 2) investigate the relationship between EL and presence of cognitive dysfunction; 3) investigate the relationship between EL and presence of psychopathology. Forty one MND patients, 39 caregivers and respective control groups composed of 39 subjects and 39 partners/friends were tested. The Italian version of the ELQ was found to have good psychometric properties. Seventy-one per cent of patients reported suffering from EL. Correlations were found between bulbar involvement and EL, and between bulbar involvement and low performance on tests of fluid intelligence and working memory. However, the cognitive profile did not correlate with any aspect of EL. The findings suggests that damage to different neurological pathways underlie cognitive change and EL, which supports the concept of MND/ALS as a multisystem disorder. Moreover the outcomes suggest that EL affects patients' everyday life with the increased anxiety and emotional frailty. The findings suggest that those involved in the care of MND patients should be more aware of the effects of EL in the management of the disease.

ALS precursor finally shaken into fibrils

There is now little doubt that the prime cause of the motor-neuron disease amyotrophic lateral sclerosis (ALS) is related to misfolding and aggregation of the metalloenzyme Cu/Zn superoxide dismutase (SOD1). Yet, SOD1 has turned out remarkably resistant to aggregation under physiological conditions in vitro. Pathologic mutant proteins that are destabilized to the extent that they fail to fold can still be stored at room temperature for long periods of time without notable signs of self-association. To produce SOD1 aggregates one has to resort to more radical measures, such as high temperature at low pH (1, 2), organic solvents (1), or oxidative cross-linking of the protein's solvent-accessible cysteines (3). Because these conditions are different from those in the cell the connection between SOD1 aggregation and ALS has remained elusive; after all, most if not all proteins contain sequences capable of nucleating aggregation (4) and can thus be forced to aggregate in vitro if the conditions are made sufficiently “persuasive.” In this issue of PNAS, Valentine and collaborators (5) present a new interesting piece to the puzzle by showing that SOD1 can be made to aggregate under conditions that are physiologically relevant. The trick seems to be simply that the solution requires appropriate agitation. After a few hours of this treatment in an orbital shaker at 250 rpm, immature molecules of wild-type SOD1 nucleate into ordered fibrillar structures similar to those observed in classical amyloidoses such as Alzheimer's and Huntington's diseases. For nucleation to occur, however, the protein also needs to be demetallated and without its stabilizing disulfide bridge. Once the seeds are formed the process can recruit more stable SOD1 species for the fibril elongation. Similar results were published independently by Furukawa et al. (6) just a few months ago.

Putting ER in its place

The importance of ER positioning is very clear in budding yeast, report Loewen et al. Get it wrong, and the cells pause division. Figure 1 The ER in budding yeast (colored lines) has less cortex (red) and more cytoplasmic (yellow) association when Scs2 is missing (bottom). Nuclear-associated ER (blue) appears normal. The positioning of particular organelles can often be important for cell function. How a cell senses organelle positioning, however, is unknown. The budding yeast is a useful model organism for getting to the bottom of this question, as its organelles move into the bud in a highly ordered manner. The ER, for example, travels along actin cables into the bud, and then attaches to the bud tip and spreads around the cortex. Sites of contact between the ER and the plasma membrane are enriched in an ER transmembrane protein called Scs2. Loewen et al. now show that Scs2 probably links the two membranes together. ER cortical distribution, they found, was abnormal in yeast lacking the protein. This phenotype was exaggerated in the bud. The team shows that this more serious defect occurs because Scs2 is normally enriched at the bud tip, where it is needed to set up the initial attachment point for the ER. In the Scs2 mutants, cell division often arrested before cytokinesis. Cytokinesis requires the formation of a ring of cytoskeletal septin proteins around the bud neck. But in Scs2 mutants, the septins were disorganized. Septin disorganization sets off a pathway known to halt the cell cycle. The team suggests that cells activate this pathway to stall division until the ER is correctly located in the bud. How the mispositioned ER interrupts proper septin deposition is yet unclear. One possibility is that a septin regulator called Cdc28, which is found on the ER, is in the wrong position to operate correctly. The authors also found that the human homologue of Scs2, called VAP, shares the same unique polarized distribution in yeast, suggesting a conserved function. VAP mutations are associated with the motorneuron disease amyotrophic lateral sclerosis. Whether wrongly placed ER in the neurons of these patients could be part of the cellular pathology—perhaps by perturbing neurotransmitter vesicle release—remains to be seen. Reference: Loewen, C.J.R., et al. 2007. J. Cell Biol. 179:467–483. [PMC free article] [PubMed]

The Amyotrophic Lateral Sclerosis Assessment Questionnaire (ALSAQ‐40): Evidence for a method of imputing missing data

The Amyotrophic Lateral Sclerosis Assessment Questionnaire (ALSAQ-40) is the most widely validated measure of health status for use with patients diagnosed with motor neuron disease/amyotrophic lateral sclerosis (MND/ALS). The questionnaire was designed to be used in studies evaluating treatment regimes where missing data may cause problems with data analyses. The purpose of this paper is to evaluate an algorithm for the imputation of missing dimension scores on the ALSAQ-40. We used a postal survey of patients diagnosed with MND/ALS. One thousand, nine hundred and seventy-nine patients were surveyed and 1093 (55.2%) questionnaires returned. Of these, complete ALSAQ-40 data was available in 854 (85.8%) cases. Data were deleted from this complete dataset, and in a randomly selected subset of 100 cases, and then imputed using the Expectation Maximization (EM) algorithm: results were then compared to the dataset prior to data deletion. Descriptive statistics, mean scores and spread of scores were almost identical between original and imputed datasets. Furthermore, the two datasets were highly correlated (intra-class correlation coefficient = 0.95 or greater), and mean differences were small (+/-1.00). We concluded that EM imputation for the ALSAQ-40 provides data that closely mirrors the original when this has been deliberately removed. Consequently, EM is likely to be appropriate for studies using the ALSAQ-40 that contain missing data points.

The expression of the chemorepellent Semaphorin 3A is selectively induced in terminal Schwann cells of a subset of neuromuscular synapses that display limited anatomical plasticity and enhanced vulnerability in motor neuron disease

Neuromuscular synapses differ markedly in their plasticity. Motor nerve terminals innervating slow muscle fibers sprout vigorously following synaptic blockage, while those innervating fast-fatigable muscle fibers fail to exhibit any sprouting. Here, we show that the axon repellent Semaphorin 3A is differentially expressed in terminal Schwann cells (TSCs) on different populations of muscle fibers: postnatal, regenerative and paralysis induced remodeling of neuromuscular connections is accompanied by increased expression of Sema3A selectively in TSCs on fast-fatigable muscle fibers. To our knowledge, this is the first demonstration of a molecular difference between TSCs on neuromuscular junctions of different subtypes of muscle fibers. Interestingly, also in a mouse model for amyotrophic lateral sclerosis (ALS), Sema3A is expressed at NMJs of fast-fatigable muscle fibers. We propose that expression of Sema3A by TSCs not only suppresses nerve terminal plasticity at specific neuromuscular synapses, but may also contribute to their early and selective loss in the motor neuron disease ALS.

Cognitive impairment in motor neuron disease with bulbar onset

Twenty-three patients with bulbar onset motor neuron disease/amyotrophic lateral sclerosis (MND/ALS) were clinically assessed. They subsequently underwent serial neuropsychological testing, event-related potentials (ERP) and SPECT studies. Cognitive impairment was defined by clinical evidence of dementia (DSM-IV and frontal evaluation) or by significant alteration indicated by neuropsychological testing (excluding patients with depression and major anxiety), or both. Eleven patients (48%) were found to be cognitively impaired. Abnormalities indicated fronto-temporal involvement, with memory impairment, alteration of judgement and reasoning, reduced speech, behavioural dyscontrol and alteration of daily living activities. This impairment correlated well with event-related potentials and SPECT studies. Event-related potentials were the most sensitive test as 100% of the impaired patients had abnormal ERP (p = 0.04). The cognitively impaired group differed from the other group mainly by gender ratio (male/female) with an important male predominance: 1.75 vs. 0.33. MND/ALS was also more severe when cognitive decline was present. This study adds further arguments for a cognitive impairment in MND/ALS. This also reinforces the hypothesis that there is continuum between MND/ALS and fronto-temporal lobe dementia.

Motor Neuron Disease/Amyotrophic Lateral Sclerosis — Lessons from Ubiquitin

Ubiquitin is a stress protein implicated in the degradation of short-lived and abnormal proteins. In a neuropathological study of 43 cases with motor neuron disease/amyotrophic lateral sclerosis (MND/ALS) and 44 control cases the distribution and specificity of Bunina bodies and ubiquitin-reactive inclusions (UBRI) were investigated. The primary motor area showed nerve cell loss in 67%, Bunina bodies in Betz cells (10%) and UBRI in small pyramidal cells (17%). Degeneration of anterior horn cells in all cases coincided with Bunina bodies (84%) and UBRI (98%) in the same location; the motor nuclei of the caudal brain stem were also involved almost to the same degree. More resistant nuclei like the oculomotor nuclei or the Onuf's nucleus showed no degeneration but UBRI in 11% and 18% of cases, respectively. Like the degenerative process, the formation of UBRI was not confined to motor nuclei but also involved the brain stem reticular formation, substantia nigra, and Clarke's nucleus showing that MND/ALS is a multiple system degeneration. UBRI were found in only one control case in the anterior horn cells and in one case in the hypoglossal nucleus showing that UBRI, although not being absolutely specific for MND/ALS, have practical value for the neuropathological diagnosis of that disease. The pathogenetical implications of UBRI in MND/ALS are discussed.

Evoked fasciculations in patients with amyotrophic lateral sclerosis

In the motor system there is a complex interplay between cortical structures and spinal cord lower motor neurons (LMN). In this system both inhibitory and excitatory neurons have relevant roles. LMN loss is a marker of motor neuron disease/amyotrophic lateral sclerosis (MND/ALS). Conventional needle electromyography (EMG) does not allow LMN loss to be quantified. Measurement of compound muscle action potential (CMAP) amplitude or area, and the neurophysiological index, provide a surrogate estimate of the number of functional motor units. Increased motor neuronal excitability is a neurophysiological marker of ALS in the context of a suspected clinical and electrophysiological diagnosis. In the LMN system, fasciculation potentials (FPs) are the earliest changes observed in affected muscles, a feature of LMN hyperexcitability. Reinnervation is best investigated by needle EMG although other methods can be explored. Moreover needle EMG give information about the temporal profile of the reinnervation process, important ancillary data. Quantitative motor unit potential analysis is a valuable method of evaluating reinnervation. The importance of FPs has been recognized in the Awaji criteria for the electrodiagnosis of ALS, criteria that are a sensitive adjunct to the revised El Escorial criteria. Finally, functionality of LMN’s, and perhaps excitability studies in motor nerves, aids understanding of the disease process, allowing measurement of potential treatment effects in clinical trials. Other investigational techniques, such as electrical impedance myography, muscle and nerve ultrasound, and spinal cord imaging methods may prove useful in future.