Shaky hands are a part of motor neuron disease phenotype: clinical and electrophysiological study of 77 patients.

BACKGROUND: In the sharp contrast with the existing literature, we frequently observe minipolymyoclonus, tremor and pseudodystonic thumb posturing in patients with motor neuron disease. We conducted a clinical and electrophysiological study to describe phenomenology, prevalence and pathophysiology of involuntary movements in motor neuron disease. METHODS: We included 77 consecutive patients. Involuntary movements were assessed at rest and on action. Patients were videotaped. Arm muscle tone, power and deep tendon reflexes were evaluated. Accelerometry with electromyography was recorded in a subset of patients. RESULTS: Involuntary movements were observed in 68.9% of patients and could be separated into rest minipolymyoclonus, thumb tremor, pseudodystonic thumb posture, action minipolymyoclonus, and action tremor. One-third of patients reported negative impact of involuntary movements on hand use. Logistic regression showed that rest minipolymyoclonus and thumb tremor were more likely to occur in patients with more prominent distal muscle weakness and less spasticity. Similarly, action involuntary movements were more likely to appear in weaker patients. Patients with brisk tendon reflexes were more likely to display action tremor than action minipolymyoclonus. Action tremor was characterized by accelerometer and corresponding electromyography peak frequency, which decreased with mass loading, suggesting a mechanical-reflex tremor. CONCLUSIONS: Involuntary movements are common, but poorly recognized feature of motor neuron disease that may add to functional impairment. Results of our study suggest that involuntary movements are likely of peripheral origin, with a non-fused contraction of enlarged motor units being a common driving mechanism. Minipolymyoclonus appears if no synchronization of motor units occurs. When synchronization occurs via stretch reflex, mechanical-reflex tremor is generated.

Chromosome 10q-linked FSHD identifies DUX4 as principal disease gene.

BACKGROUND: Facioscapulohumeral dystrophy (FSHD) is an inherited muscular dystrophy clinically characterised by muscle weakness starting with the facial and upper extremity muscles. A disease model has been developed that postulates that failure in somatic repression of the transcription factor DUX4 embedded in the D4Z4 repeat on chromosome 4q causes FSHD. However, due to the position of the D4Z4 repeat close to the telomere and the complex genetic and epigenetic aetiology of FSHD, there is ongoing debate about the transcriptional deregulation of closely linked genes and their involvement in FSHD. METHOD: Detailed genetic characterisation and gene expression analysis of patients with clinically confirmed FSHD and control individuals. RESULTS: Identification of two FSHD families in which the disease is caused by repeat contraction and DUX4 expression from chromosome 10 due to a de novo D4Z4 repeat exchange between chromosomes 4 and 10. We show that the genetic lesion causal to FSHD in these families is physically separated from other candidate genes on chromosome 4. We demonstrate that muscle cell cultures from affected family members exhibit the characteristic molecular features of FSHD, including DUX4 and DUX4 target gene expression, without showing evidence for transcriptional deregulation of other chromosome 4-specific candidate genes. CONCLUSION: This study shows that in rare situations, FSHD can occur on chromosome 10 due to an interchromosomal rearrangement with the FSHD locus on chromosome 4q. These findings provide further evidence that DUX4 derepression is the dominant disease pathway for FSHD. Hence, therapeutic strategies should focus on DUX4 as the primary target.

Improvements in the multidisciplinary care are beneficial for survival in amyotrophic lateral sclerosis (ALS): experience from a tertiary ALS center.

Objective: The Ljubljana ALS Centre, established in 2002, is the only tertiary center for amyotrophic lateral sclerosis (ALS) in Slovenia. The aim of our study was to evaluate the impact of therapeutic interventions and improvements in the multidisciplinary care on the survival of our patients.Methods: All patients diagnosed with ALS at our center during years 2003-2005 (early group) and 2011-2012 (late group) were included in this retrospective cohort study (n = 124). Kaplan-Meier survival analysis and multiple regression analysis with Cox proportional hazards model were performed to compare survival and to evaluate the differences between the two cohorts.Results: Median survival from the time of diagnosis was 13.0 (95% CI 10.2-15.8) months in the early group and 21.8 (95% CI 17.2-26.4) months in the late group (p = 0.005). In the Cox proportional hazards analysis, the late group of patients was associated with better survival independently of all other prognostic factors (hazard ratio (HR)=0.51, 95% CI = 0.32-0.81, p = 0.004). Survival was also associated with patients' age, use of noninvasive ventilation (NIV) and gastrostomy. The model fit significantly improved when the interaction between the NIV use and the observed time period was added to the model (HR = 0.34, 95% CI = 0.12-0.96, p = 0.041).Conclusions: Our findings suggest that improvements in the multidisciplinary care were beneficial for survival of our patients with ALS. The survival benefit in the late group of our patients could be partially explained by the improvements in the NIV use at our center.

IMG-01 The spectrum of involuntary movements in patients with motor neuron disease: a cross-sectional study.

Background: We have commonly observed involuntary jerks and tremor in patients with motor neuron disease (MND), even though these features are not considered typical for the disease.Objectives: We conducted prospective clinical and electrophysiological study to explore the prevalence, phenomenology and pathophysiology of involuntary movements in MND.Methods: Seventy-four consecutive patients were clinically examined and video-recorded. Based on regularity and distribution, movements observed at rest position were classified as minipolymyoclonus (MPMC) or rest thumb tremor (RTT) and movements present during action as action MPMC or action tremor. In 11 patients with tremor, accelerometry was recorded at (a) rest position, (b) with arms outstretched (postural condition) and (c) at postural condition with 500 g mass attached to the hand.Results: Involuntary movements were present in 54 patients (73%). Rest MPMC was present in 26 patients (35%), RTT in 22 patients (31%), action MPMC in 22 patients (30%) and action tremor in 20 patients (27%), with some overlap. Sixteen patients (22%) reported negative impact of involuntary movements on their ability to use hands. Regression model showed that lower distal muscle power and less prominent upper motor neuron involvement significantly increased the odds of MND patient having involuntary movements. Sex, age and disease duration did not significantly predict the occurrence of involuntary movements. At rest, tremor frequency ranged from 5.2 to 8.2 Hz, at postural position from 4.9 Hz to 7.6 Hz and during postural position with mass attached from 3.6 Hz to 7.6 Hz. On the group level, tremor peak frequency statistically significantly decreased from 6.1 Hz to 5 Hz without versus with loading.Discussion and conclusions: Involuntary movements are very common yet largely overlooked feature of MND that may also have negative impact on patient's functional abilities. Lower distal muscle power increases and the presence of upper motor neuron signs decreases the probability of involuntary movements. Together with finding of decrease in tremor frequency with mass loading, these results suggest that generation of involuntary movements is of peripheral origin.

Differential Expression of Several miRNAs and the Host Genes AATK and DNM2 in Leukocytes of Sporadic ALS Patients.

Genetic studies have managed to explain many cases of familial amyotrophic lateral sclerosis (ALS) through mutations in several genes. However, the cause of a majority of sporadic cases remains unknown. Recently, epigenetics, especially miRNA studies, show some promising aspects. We aimed to evaluate the differential expression of 10 miRNAs, including miR-9, miR-338, miR-638, miR-663a, miR-124a, miR-143, miR-451a, miR-132, miR-206, and let-7b, for which some connection to ALS was shown previously in ALS culture cells, animal models or patients, and in three miRNA host genes, including C1orf61 (miR-9), AATK (miR-338), and DNM2 (miR-638), in leukocyte samples of 84 patients with sporadic ALS. We observed significant aberrant dysregulation across our patient cohort for miR-124a, miR-206, miR-9, let-7b, and miR-638. Since we did not use neurological controls we cannot rule out that the revealed differences in expression of investigated miRNAs are specific for ALS. Nevertheless, the group of these five miRNAs is worth of additional research in leukocytes of larger cohorts from different populations in order to verify their potential association to ALS disease. We also detected a significant up-regulation of the AAKT gene and down-regulation of the DNM2 gene, and thus, for the first time, we connected these with sporadic ALS cases. These findings open up new research toward miRNAs as diagnostic biomarkers and epigenetic processes involved in ALS. The detected significant deregulation of AAKT and DNM2 in sporadic ALS also represents an interesting finding. The DNM2 gene was previously found to be mutated in Charcot-Marie-Tooth neuropathy-type CMT2M and centronuclear myopathy (CNM). In addition, as recent studies connected AATK and frontotemporal dementia (FTD) and DNM2 and hereditary spastic paraplegia (HSP), these two genes together with our results genetically connect, at least in part, five diseases, including FTD, HSP, Charcot-Marie-Tooth (type CMT2M), CNM, and ALS, thus opening future research toward a better understanding of the cell biology involved in these partly overlapping pathologies.

Differential expression of microRNAs and other small RNAs in muscle tissue of patients with ALS and healthy age-matched controls.

Amyotrophic lateral sclerosis is a late-onset disorder primarily affecting motor neurons and leading to progressive and lethal skeletal muscle atrophy. Small RNAs, including microRNAs (miRNAs), can serve as important regulators of gene expression and can act both globally and in a tissue-/cell-type-specific manner. In muscle, miRNAs called myomiRs govern important processes and are deregulated in various disorders. Several myomiRs have shown promise for therapeutic use in cellular and animal models of ALS; however, the exact miRNA species differentially expressed in muscle tissue of ALS patients remain unknown. Following small RNA-Seq, we compared the expression of small RNAs in muscle tissue of ALS patients and healthy age-matched controls. The identified snoRNAs, mtRNAs and other small RNAs provide possible molecular links between insulin signaling and ALS. Furthermore, the identified miRNAs are predicted to target proteins that are involved in both normal processes and various muscle disorders and indicate muscle tissue is undergoing active reinnervation/compensatory attempts thus providing targets for further research and therapy development in ALS.

Separating the Idea from the Action: A sLORETA Study.

Simple imaginary movements activate similar cortical and subcortical areas to actual movements, chiefly in the sensory-motor network. However, only a few studies also examined the imagery of more skilful movements such as reaching. Ten volunteers performed reaching movements or imagined the same movements. EEG was simultaneously recorded and analysed with sLORETA, which compared the preparation for actual and imagined reaching with respect to their baseline and between tasks. Major differences between them were found at three time intervals after target presentation, always in favour of the actual reaching condition. The first one was from 160 to 220 msec in the frontal and parietal regions. The second difference was evident from 220 to 320 msec in the premotor cortex. The third difference was evident from 320 msec, mainly in the perirolandic region. Also, the anterior and posterior cingulate cortices were widely involved, in both tasks. We suggest the existence of two separate systems which may work together during actual reaching programming. The first one involves structures such as the premotor cortex, supplementary motor area and primary motor cortex, together with the parietal and occipital cortex. This system may integrate extrinsic target coordinates with proprioceptive information from the reaching arm and pre-stored programs in the associative motor cortex. It is activated strongly and involves more cortical areas in actual than imagined reaching. The second system, common to both tasks, involves anterior and posterior cingulate cortices, with the possible role of contributing awareness and focusing the various components of the process.

Peripheral nerve ultrasonography in patients with transthyretin amyloidosis.

OBJECTIVE: To systematically study peripheral nerve morphology in patients with transthyretin (TTR) amyloidosis and TTR gene mutation carriers using high-resolution ultrasonography (US). METHODS: In this prospective cross-sectional study we took a structured history, performed neurological examination, and measured peripheral nerve cross-sectional areas (CSAs) bilaterally at 28 standard locations using US. Demographic and US findings were compared to controls. RESULTS: Peripheral nerve CSAs were significantly larger in 33 patients with familial amyloid polyneuropathy (FAP) compared to 50 controls, most dramatically at the common entrapment sites (median nerve at the wrist, ulnar nerve at the elbow), and in the proximal nerve segments (median nerve in the upper arm, sciatic nerve in the thigh). Findings in 21 asymptomatic TTR gene mutation carriers were less marked compared to controls, with CSAs being larger only in the median nerve in the upper arm. Nerve CSAs correlated with abnormalities on nerve conduction studies. CONCLUSION: Using US, we confirmed previous pathohistological and imaging reports in FAP of the most pronounced peripheral nerve thickening in the proximal limb segments. SIGNIFICANCE: Similar to US findings in diabetic and vasculitic neuropathies these predominantly proximal locations of nerve thickening may be attributed to ischaemic nerve damage caused by poor perfusion in the watershed zones along proximal limb segments.

Beyond aphasia: Altered EEG connectivity in Broca's patients during working memory task.

Broca's region and adjacent cortex presumably take part in working memory (WM) processes. Electrophysiologically, these processes are reflected in synchronized oscillations. We present the first study exploring the effects of a stroke causing Broca's aphasia on these processes and specifically on synchronized functional WM networks. We used high-density EEG and coherence analysis to map WM networks in ten Broca's patients and ten healthy controls during verbal WM task. Our results demonstrate that a stroke resulting in Broca's aphasia also alters two distinct WM networks. These theta and gamma functional networks likely reflect the executive and the phonological processes, respectively. The striking imbalance between task-related theta synchronization and desynchronization in Broca's patients might represent a disrupted balance between task-positive and WM-irrelevant functional networks. There is complete disintegration of left fronto-centroparietal gamma network in Broca's patients, which could reflect the damaged phonological loop.

Genome-wide association analyses identify new risk variants and the genetic architecture of amyotrophic lateral sclerosis.

To elucidate the genetic architecture of amyotrophic lateral sclerosis (ALS) and find associated loci, we assembled a custom imputation reference panel from whole-genome-sequenced patients with ALS and matched controls (n = 1,861). Through imputation and mixed-model association analysis in 12,577 cases and 23,475 controls, combined with 2,579 cases and 2,767 controls in an independent replication cohort, we fine-mapped a new risk locus on chromosome 21 and identified C21orf2 as a gene associated with ALS risk. In addition, we identified MOBP and SCFD1 as new associated risk loci. We established evidence of ALS being a complex genetic trait with a polygenic architecture. Furthermore, we estimated the SNP-based heritability at 8.5%, with a distinct and important role for low-frequency variants (frequency 1-10%). This study motivates the interrogation of larger samples with full genome coverage to identify rare causal variants that underpin ALS risk.

The role of transcranial magnetic stimulation in evaluation of motor cortex excitability in Rett syndrome.

UNLABELLED: Rett syndrome (RTT) is a frequent neurodevelopmental disorder confirmed by clinical criteria and supported by the methyl-CpG-binding protein 2 gene (MECP2) mutation. A short central motor conduction time (CMCT) was reported in transcranial magnetic stimulation (TMS) studies performed in RTT. This was attributed to hyperexcitability of the motor cortex and/or spinal motor neurons, but was not studied further. AIM: We performed TMS in RTT to evaluate motor cortex excitability by determining the cortical motor threshold (CMT) and motor cortex inhibition by the cortical silent period (CSP) besides measuring CMCT. METHODS: Single-pulse TMS was performed in 17 Rett patients, diagnosed by clinical criteria and MECP2 mutation testing, and the same number of healthy controls. The outcome measures were compared between RTT groups with different antiepileptic drugs (AED) and those with and without the MECP2 mutation. RESULTS: CMCT was shorter, but we found elevated CMT and shorter CSP, which suggests decreased excitatory and inhibitory motor cortical function. The outcome was independent of AED and the presence or absence of the MECP2 mutation. INTERPRETATION: Decreased excitatory and inhibitory motor cortical function could explain the short CMCT, with higher stimulus intensities needed to excite pyramidal neurons.

The electrophysiological correlates of the working memory subcomponents: evidence from high-density EEG and coherence analysis.

Synchronization between prefrontal (executive) and posterior (association) cortices seems a plausible mechanism for temporary maintenance of information. However, while EEG studies reported involvement of (pre)frontal midline structures in synchronization, functional neuroimaging elucidated the importance of lateral prefrontal cortex (PFC) in working memory (WM). Verbal and spatial WM rely on lateralized subsystems (phonological loop and visuospatial sketchpad, respectively), yet only trends for hemispheric dissociation of networks supporting rehearsal of verbal and spatial information were identified by EEG. As oscillatory activity is WM load dependent, we applied an individually tailored submaximal load for verbal (V) and spatial (S) task to enhance synchronization in the relevant functional networks. To map these networks, we used high-density EEG and coherence analysis. Our results imply that the synchronized activity is limited to highly specialized areas that correspond well with the areas identified by functional neuroimaging. In both V and S task, two independent networks of theta synchronization involving dorsolateral PFC of each hemisphere were revealed. In V task, left prefrontal and left parietal areas were functionally coupled in gamma frequencies. Theta synchronization thus provides the necessary interface for storage and manipulation of information, while left-lateralized gamma synchronization could represent the EEG correlate of the phonological loop.

Genetic analysis of amyotrophic lateral sclerosis in the Slovenian population.

Amyotrophic lateral sclerosis (ALS) is a complex fatal neurodegenerative disease characterized by progressive degeneration and loss of upper motor neurons in the cerebral cortex and lower motor neurons in brainstem and spinal cord. We established the frequencies of mutations in 4 major ALS-associated genes, SOD1, TARDBP, FUS, and C9ORF72 in a representative cohort of 85 Slovenian patients with sporadic form of ALS. Pathogenic massive hexanucleotide repeat expansion mutation in C9ORF72 was detected in 5.9% of patients and was the most common cause of the disease. In the remaining 3 genes, we identified 4 changes in 3 patients, p.Val14Met in SOD1, silent mutation p.Arg522Arg in FUS, and p.Gly93Cys in SOD1 together with a novel synonymous variant c.990A>G (p.Leu330Leu) in TARDBP gene, respectively. This study represents the first genetic screening of major causative genes for ALS in a cohort of sporadic ALS patients from Slovenia and is according to our knowledge the first such study in Slavic population. Overall, we genetically characterized 8.2% sporadic ALS patients.

Decreased movement-related beta desynchronization and impaired post-movement beta rebound in amyotrophic lateral sclerosis.

OBJECTIVE: This study explored event-related desynchronization (ERD) and synchronization (ERS) in amyotrophic lateral sclerosis (ALS) to quantify cortical sensorimotor processes during volitional movements. We furthermore compared ERD/ERS measures with clinical scores and movement-related cortical potential (MRCP) amplitudes. METHODS: Electroencephalograms were recorded while 21 ALS patients and 19 controls performed two self-paced motor tasks: sniffing and right index finger flexion. Based on Wavelet analysis the alpha and beta frequency bands were selected for subsequent evaluation. RESULTS: Patients generated significantly smaller resting alpha spectral power density (SPD) and smaller beta ERD compared to controls. Additionally patients exhibited merely unilateral post-movement ERS (beta rebound) whereas this phenomenon was bilateral in controls. ERD/ERS amplitudes did not correlate with corresponding MRCPs for either patients or controls. CONCLUSIONS: The smaller resting alpha SPD and beta ERD and asymmetrical appearance of beta ERS in patients compared to controls could be the result of pyramidal cell degeneration and/or corpus callosum involvement in ALS. SIGNIFICANCE: These results support the notion of reduced movement preparation in ALS involving also areas outside the motor cortex. Furthermore post-movement cortical inhibition seems to be impaired in ALS. ERD/ERS and MRCP are found to be independent measures of cortical motor functions in ALS.

Assessment of the haptic robot as a new tool for the study of the neural control of reaching.

Current experimental methods for the study of reaching in the MRI environment do not exactly mimic actual reaching, due to constrains in movement which are imposed by the MRI machine itself. We tested a haptic robot (HR) as such a tool. Positive results would also be promising for combined use of fMRI and EEG to study reaching. Twenty right-handed subjects performed reaching tasks with their right hand with and without the HR. Reaction time, movement time (MT), accuracy, event-related potentials (ERPs) and event-related desynchronisation/synchronisation (ERD/ERS) were studied. Reaction times and accuracies did not differ significantly between the two tasks, while the MT was significantly longer in HR reaching (959 vs. 447 ms). We identified two positive and two negative ERP peaks across all leads in both tasks. The latencies of the P1 and N2 peaks were significantly longer in HR reaching, while there were no significant differences in the P3 and N4 latencies. ERD/ERS topographies were similar between tasks and similar to other reaching studies. Main difference was in ERS rebound which was observed only in actual reaching. Probable reason was significantly larger MT. We found that reaching with the HR engages similar neural structures as in actual reaching. Although there are some constrains, its use may be superior to other techniques used for reaching studies in the MRI environment, where freedom of movement is limited.

Movement-related cortical potentials in ALS increase at lower and decrease at higher upper motor neuron burden scores.

Our aim was to investigate changes in movement-related cortical potentials (MRCPs) in ALS patients with different degrees of upper motor neuron (UMN) involvement. Since respiratory failure is the main cause of death in ALS, changes in inspiratory-related (sniffing) potentials were studied in addition to finger-flexion-related potentials. Subjects (21 ALS, 19 controls) performed two self-paced motor tasks while their EEGs were recorded. The first task required flexions of the right index finger and the second, brisk nasal inspirations. The early (BP1), late (BP2) and motor potential (MP) components of MRCPs were evaluated. Results showed that patients generated higher MRCPs than controls. However, this effect was most significant in the subgroup of patients with low UMN burden (LUB). The high UMN burden (HUB) subgroup did not differ from controls, but had significantly lower MP amplitudes than the LUB subgroup. Progressive UMN deterioration was associated with an initial increase, followed by a later decrease, in MP amplitudes in ALS. In conclusion, the increased MRCPs in LUB compared to HUB patients indicate different processes of ALS pathophysiology that force opposing changes in MRCP amplitudes.

Sniffing-related motor cortical potential: topography and possible generators.

This study estimated the whole-scalp topography and possible generators of the cortical potential associated with volitional self-paced inspirations (sniffs). In 17 healthy subjects we recorded a 32-channel electroencephalogram (EEG) during sniffing, for comparison during finger flexions. We averaged the EEG with respect to movement onset, and performed current source density and principal component analysis on the grand averaged data. We identified an early negative sniffing-related cortical potential starting ∼1.5s before movement at the vertex, which, in its time-course and dipole orientation, closely resembled Bereitshaftspotential preceding finger flexions. Around the movement onset, its topography became unique with three negative current sources: one at the vertex, and two bilaterally over the fronto-temporal derivations. We conclude that sequential cortical activation in preparation for sniffing is similar to other volitional movements. The current sources at sniff onset at the vertex likely reflect somatotopic motor representation of the diaphragm, neck and intercostal muscles, whereas current sources over fronto-temporal derivations likely reflect the somatotopic representation of the orofacial muscles.

Inspiratory- and finger-flexion-related cortical potentials in patients with amyotrophic lateral sclerosis--an exploratory study.

OBJECTIVE: Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder characterized by degeneration of the upper and lower motor neurons. Each voluntary movement, including inspiration, is preceded by movement-related cortical potential (MRCP) that can be recorded from the scalp. MRCPs of ALS patients with severe upper motor neuron involvement are smaller. Our aim was to explore whether the inspiratory-(sniffing)-related cortical potentials (SRCPs) and index-finger-flexion MRCPs (FFRCPs) can be used as markers of cortical involvement in ALS. METHODS: Thirteen ALS patients and 15 healthy volunteers were assessed for their hand dexterity and strength, respiratory function, speech capacity, spasticity, electromyographic parameters and functional rating scales. EEG was recorded during self-paced sniffing and the right index finger flexion. The MRCP amplitudes were assessed at the relevant electrode positions. RESULTS: No statistically significant difference was found between the MRCP amplitudes of the ALS patients and the control subjects. However, patients with more severely affected upper limb functions generated smaller FFRCPs and those with more affected respiratory functions generated smaller SRCPs. Excessively high FFRCPs were associated with better while excessively low FFRCPs with worse scores on some of the clinical measures of the upper limb function. CONCLUSION: Our preliminary results demonstrate that it is feasible to record SRCP in ALS patients, which combined with FFRCP, may be useful to determine the spectrum of motor control changes in this population.