Early onset hereditary neuronopathies: an update on non-5q motor neuron diseases.

Hereditary motor neuropathies (HMN) were first defined as a group of neuromuscular disorders characterized by lower motor neuron dysfunction, slowly progressive length-dependent distal muscle weakness and atrophy, without sensory involvement. Their cumulative estimated prevalence is 2.14/100 000 and, to date, around 30 causative genes have been identified with autosomal dominant, recessive,and X-linked inheritance. Despite the advances of next generation sequencing, more than 60% of patients with HMN remain genetically uncharacterized. Of note, we are increasingly aware of the broad range of phenotypes caused by pathogenic variants in the same gene and of the considerable clinical and genetic overlap between HMN and other conditions, such as Charcot-Marie-Tooth type 2 (axonal), spinal muscular atrophy with lower extremities predominance, neurogenic arthrogryposis multiplex congenita and juvenile amyotrophic lateral sclerosis. Considering that most HMN present during childhood, in this review we primarily aim to summarize key clinical features of paediatric forms, including recent data on novel phenotypes, to help guide differential diagnosis and genetic testing. Second, we describe newly identified causative genes and molecular mechanisms, and discuss how the discovery of these is changing the paradigm through which we approach this group of conditions.

Limitations in daily activities and general perception of quality of life: Long term follow-up in patients with anti-myelin-glycoprotein antibody polyneuropathy.

In this study, we assessed the modifications over time of daily activities and quality of life (QoL) in 32 subjects with anti-myelin-glycoprotein (MAG) antibody neuropathy. A widespread panel including clinical scores and patient-reported questionnaires, in compliance of the terms by the International Classification of Functioning, Disability, and Health (ICF) of the World Health Organization (WHO), was employed at enrollment (T0) and at follow-up evaluation (T1) after a mean interval of 15.4 ± 5.7 months. The Sensory Modality Sum score (SMS) at four limbs showed a significant worsening over time (mean score 27.2 ± 3.9 at T0 vs 25.7 ± 3 at T1 at upper limbs, P = .03; 20.5 ± 4.8 at T0 vs 18.6 ± 5.9 at T1 at lower limbs, P = .04). The Visual Analogue Scale (VAS) for pain significantly worsened at upper limbs at T1 (mean values 0.84 ± 1.95 at T0 vs 1.78 ± 2.6 at T1, P = .03). All the other tests did not show significant differences between T0 and T1. In the subgroup who underwent rituximab (15/32 treated before T0, 3/32 patients treated between T0 and T1 with median interval of 1 year), no significant differences were observed between T0 and T1. Despite the quite long follow-up, statistical significance was not achieved either for the limited number of patients or for the lack of sensitive outcome measures. In our cohort, the significant worsening of the SMS and VAS after a median of 14 months can be considered as a reliable expression of the natural history of the disease, and suggest that these scales might represent possible outcome measures in anti-MAG antibody neuropathy.

Brain MR Imaging in Patients with Lower Motor Neuron-Predominant Disease.

Purpose To investigate the patterns of cortical thinning and white matter tract damage in patients with lower motor neuron (LMN)-predominant disease compared with healthy control subjects and those with classic amyotrophic lateral sclerosis (ALS) and to evaluate the relationship between brain structural changes and clinical and cognitive features in these patients. Materials and Methods This study was approved by the local ethical committee, and written informed consent was obtained from all subjects before enrollment. Twenty-eight patients with LMN-predominant disease were compared with 55 patients with ALS and 56 healthy control subjects. Patients underwent a clinical and neuropsychological assessment and T1-weighted and diffusion-tensor magnetic resonance (MR) imaging. Surface-based morphometry was used to assess cortical thickness. Tract-based spatial statistics and tractography were used to study white matter tract damage. Results Patients with LMN-predominant disease did not show differences compared with healthy control subjects in cortical thickness and diffusion-tensor MR imaging metrics. Patients with ALS showed cortical thinning of the motor-related cortices and a distributed involvement of the prefrontal, temporal, and parietal gyri (P < .05, false discovery rate corrected). Patients with ALS also showed white matter damage along motor and extramotor tracts compared with control subjects and patients with LMN-predominant disease (tract-based spatial statistics: P < .05, family-wise error corrected; tractography: P values < .001 to .05, false discovery rate corrected). In patients with LMN-predominant disease, cognitive deficits correlated with alterations in diffusivity in the left cingulum (r = -0.66, P = .01) and superior longitudinal fasciculus (r = -0.65, P = .05). Conclusion Motor and extramotor cortical thinning and diffusion-tensor MR imaging alterations were specific for motor neuron disease phenotypes, with clinically overt upper motor neuron involvement. However, the lack of significant differences in cortical thickness between subjects with LMN-predominant disease and those with ALS and cognitive deficits associated with alterations in diffusivity in patients with LMN-predominant disease suggest that investigating brain structural and microstructural MR imaging features may provide markers of central nervous system damage in patients with rare motor neuron disease. (©) RSNA, 2016 Online supplemental material is available for this article.

Structural and Functional Brain Network Connectivity at Different King's Stages in Patients With Amyotrophic Lateral Sclerosis.

BACKGROUND AND OBJECTIVES: There is currently no validated disease-stage biomarker for amyotrophic lateral sclerosis (ALS). The identification of quantitative and reproducible markers of disease stratification in ALS is fundamental for study design definition and inclusion of homogenous patient cohorts into clinical trials. Our aim was to assess the rearrangements of structural and functional brain connectivity underlying the clinical stages of ALS, to suggest objective, reproducible measures provided by MRI connectomics mirroring disease staging. METHODS: In this observational study, patients with ALS and healthy controls (HCs) underwent clinical evaluation and brain MRI on a 3T scanner. Patients were classified into 4 groups, according to the King's staging system. Structural and functional brain connectivity matrices were obtained using diffusion tensor and resting-state fMRI data, respectively. Whole-brain network-based statistics (NBS) analysis and comparisons of intraregional and inter-regional connectivity values using analysis of covariance models were performed between groups. Correlations between MRI and clinical/cognitive measures were tested using Pearson coefficient. RESULTS: One hundred four patients with ALS and 61 age-matched and sex-matched HCs were included. NBS and regional connectivity analyses demonstrated a progressive decrease of intranetwork and internetwork structural connectivity of sensorimotor regions at increasing ALS stages in our cohort, compared with HCs. By contrast, functional connectivity showed divergent patterns between King's stages 3 (increase in basal ganglia and temporal circuits [p = 0.04 and p = 0.05, respectively]) and 4 (frontotemporal decrease [p = 0.03]), suggesting a complex interplay between opposite phenomena in late stages of the disease. Intraregional sensorimotor structural connectivity was correlated with ALS Functional Rating Scale-revised (ALSFRS-r) score (r = 0.31, p < 0.001) and upper motor neuron burden (r = -0.25, p = 0.01). Inter-regional frontal-sensorimotor structural connectivity was also correlated with ALSFRS-r (r = 0.24, p = 0.02). No correlations with cognitive measures were found. DISCUSSION: MRI of the brain allows to demonstrate and quantify increasing disruption of structural connectivity involving the sensorimotor networks in ALS, mirroring disease stages. Frontotemporal functional disconnection seems to characterize only advanced disease phases. Our findings support the utility of MRI connectomics to stratify patients and stage brain pathology in ALS in a reproducible way, which may mirror clinical progression.

Muscle hypertrophy following acquired neurogenic injury: systematic review and analysis of existing literature.

OBJECTIVES: Neurogenic muscle hypertrophy (NMH) is a rare condition characterized by focal muscle hypertrophy caused by chronic partial nervous injury. Given its infrequency, underlying mechanisms remain poorly understood. Inspired by two clinical cases, we conducted a systematic review to gain insights into the different aspects of NMH. METHODS: We systematically searched online databases up until May 30, 2023, for reports of muscle hypertrophy attributed to acquired neurogenic factors. We conducted an exploratory analysis to identify commonly associated features. We also report two representative clinical cases. RESULTS: Our search identified 63 reports, describing 93 NMH cases, to which we added our two cases. NMH predominantly affects patients with compressive radiculopathy (68.4%), negligible muscular weakness (93.3%), and a chronic increase in muscle bulk. A striking finding in most neurophysiological studies (60.0%) is profuse spontaneous discharges, often hindering the analysis of voluntary traces. Some patients exhibited features consistent with more significant muscle damage, including higher creatine phosphokinase levels, muscle pain, and inflammatory muscle infiltration. These patients are sometimes referred to in literature as "focal myositis." Treatment encompassed corticosteroid, Botulinum Toxin A, decompressive surgery, antiepileptic medications, and nerve blocks, demonstrating varying degrees of efficacy. Botulinum Toxin A yielded the most favorable response in terms of reducing spontaneous discharges. INTERPRETATION: This systematic review aims to provide a clear description and categorization of this uncommon presentation of an often-overlooked neurological disorder. Though questions remain about the underlying mechanism, evidence suggests that aberrant fiber overstimulation along with increased workload that promotes focal damage may result in muscle hypertrophy. This may serve as a guide for therapeutic interventions.

Comparative Analysis of C9orf72 and Sporadic Disease in a Large Multicenter ALS Population: The Effect of Male Sex on Survival of C9orf72 Positive Patients.

We investigated whether the C9orf72 repeat expansion is associated with specific clinical features, comorbidities, and prognosis in patients with amyotrophic lateral sclerosis (ALS). A cohort of 1417 ALS patients, diagnosed between January 1, 2009 and December 31, 2013 by 13 Italian ALS Referral Centers, was screened for the C9orf72 repeat expansion, and the analyses were performed comparing patients carrying this expansion (ALS-C9Pos) to those negative for this and other explored ALS-related mutations (ALS without genetic mutations, ALSwoGM). Compared to the ALSwoGM group, ALS-C9Pos patients (n = 84) were younger at disease onset, at the first clinical observation and at diagnosis (p < 0.001). After correcting for these differences, we found that ALS-C9Pos patients had higher odds of bulbar onset, diagnosis of frontotemporal dementia (FTD) and family history of ALS, FTD, and Alzheimer's disease and had lower odds of spinal onset, non-invasive ventilation, hypertension and psychiatric diseases than ALSwoGM patients. Among these variables, those related to shorter survival time were: bulbar onset, presence of FTD, hypertension, psychiatric disease, and family history of ALS (p < 0.05). Cox proportional hazards regression multivariate analysis suggested that carrying the C9orf72 repeat expansion was an independent factor negatively impacting on survival time in men (HR 1.58, 95% CI 1.07-2.33, p = 0.021), but not in women (p > 0.05) as well as in the whole sample (p > 0.05). When compared to ALSwoGM, ALS-C9Pos showed an earlier disease onset, no significant diagnostic delay and a higher odds of bulbar onset, FTD and family history of ALS and dementia. Moreover, male sex drove the negative effect of expanded variant on survival, confirming the hypothesis that sex is likely to be a crucial factor in the biology of C9orf72-related disease.

Functioning and quality of life in patients with neuropathy associated with anti-MAG antibodies.

Although anti-myelin-associated glycoprotein (MAG) antibody neuropathy is reported as a slowly progressive disease, it can lead to significant disability and impairment of health-related quality of life (HR-QoL) and social participation. The aim of this cross-sectional study was to evaluate the functioning and HR-QoL determinants in 67 patients with anti-MAG neuropathy in terms of the International Classification of Functioning, Disability, and Health (ICF). Evaluations included: Medical Research Council (MRC) sum score, Sensory Modality Sum score (SMS), Berg balance scale (BBS), Fatigue Severity Scale (FSS), Visual Analogue Scale (VAS) for pain, 9-Hole Peg Test (9-HPT), 6-min Walk Distance (6MWD), Impact on Participation and Autonomy (IPA) and the physical component score (PCS) and mental component score (MCS) of the short-form-36 health status scale (SF-36) HR-QoL measure. In the regression models, 6MWD was the most reliable predictor of PCS, explaining the 52% of its variance, while the strongest determinants of 6MWD were BBS and FSS, explaining the 41% of its variance. Consistently, VAS and BBS were good predictor of PCS, explaining together 54% of its variance. FSS was the most reliable determinant of MCS, explaining 25% of its variance. SMS and MRC were not QoL determinants. The results of our study suggest that 6MWD and FSS might be considered as potential meaningful outcome measures in future clinical trials. Furthermore, neurorehabilitation interventions aimed at improving balance and walking performance, fatigue management, and specific pain relief therapy should be considered to ameliorate participation in social life and HR-QoL in anti-MAG neuropathy patients.

Comorbidity of dementia with amyotrophic lateral sclerosis (ALS): insights from a large multicenter Italian cohort.

To assess the association, at diagnosis, between amyotrophic lateral sclerosis (ALS) and dementia in a large cohort of well-characterized Italian patients. We investigated the phenotypic profile of 1638 incident patients with definite, probable or laboratory-supported probable ALS, diagnosed from January 2009 to December 2013 in 13 Italian Referral Centers, located in 10 Italian Regions, and classified in two independent subsamples accounting for presence or not of dementia. The collected ALS features, including survival and other follow-up data, were compared between the two subgroups using a one-way analysis of variance and Chi-square test, as appropriate, logistic regression models and Kaplan-Meier survival analysis. Between-subgroup comparisons showed an older age at clinical observation (p = .006), at onset and at diagnosis (p = .002) in demented versus non demented ALS patients. After adjustment for these variables, diagnosis of dementia was significantly associated with higher odds of family history of ALS (p = .001) and frontotemporal dementia (p = .003) and of bulbar onset (p = .004), and lower odds of flail leg phenotype (p = .019) and spinal onset (p = .008). The median survival time was shorter in demented versus non-demented patients, especially in case of classical, bulbar and flail limb phenotypes and both bulbar and spinal onset. Our multicenter study emphasized the importance of an early diagnosis of comorbid dementia in ALS patients, which may have clinical impact and prognostic relevance. Moreover, our results may give further inputs to validation of ALS-specific tools for the screening of cognitive impairment in clinical practice.

Factors predicting survival in ALS: a multicenter Italian study.

The aim of this multicenter, retrospective study is to investigate the role of clinical characteristics and therapeutic intervention on ALS prognosis. The study included patients diagnosed from January 1, 2009 to December 31, 2013 in 13 Italian referral centers for ALS located in 10 Italian regions. Caring neurologists collected a detailed phenotypic profile and follow-up data until death into an electronic database. One center collected also data from a population-based registry for ALS. 2648 incident cases were collected. The median survival time from onset to death/tracheostomy was 44 months (SE 1.18, CI 42-46). According to univariate analysis, factors related to survival from onset to death/tracheostomy were: age at onset, diagnostic delay, site of onset, phenotype, degree of certainty at diagnosis according to revised El Escorial criteria (R-EEC), presence/absence of dementia, BMI at diagnosis, patients' provenance. In the multivariate analysis, age at onset, diagnostic delay, phenotypes but not site of onset, presence/absence of dementia, BMI, riluzole use, R-EEC criteria were independent prognostic factors of survival in ALS. We compared patients from an ALS Registry with patients from tertiary centers; the latter ones were younger, less frequently bulbar, but more frequently familial and definite at diagnosis. Our large, multicenter study demonstrated the role of some clinical and demographic factors on ALS survival, and showed some interesting differences between referral centers' patients and the general ALS population. These results can be helpful for clinical practice, in clinical trial design and to validate new tools to predict disease progression.