Flail arm syndrome: a distinctive variant of amyotrophic lateral sclerosis

Flail arm syndrome due to duplication mutations in the SMN1 gene: A case report

RATIONALE

Flail arm syndrome (FAS) only involves the upper limbs early stage and manifests as proximal weakness and atrophy of both upper limbs and decreased tendon reflexes. As a benign variant type of amyotrophic lateral sclerosis, FAS progresses slowly, with no lower motor neuron signs in the lower limbs or bulbar muscles within 12 months after onset.

PATIENT CONCERNS

A 49-year-old male patient was admitted to the hospital with a 15-month history of proximal weakness and muscle atrophy in both upper limbs. His other symptoms and signs were not obvious.

DIAGNOSES

Gene test results indicated that there were duplication mutations in the exon 7 to 8 region of the SMN1 gene.

LESSONS

The abnormal duplication of exons 7 and 8 of the SMN1 gene in this patient may increase the risk of FAS. Further studies are needed to identify the dominant genes and genetic factors causing males to be susceptible to FAS.

Current State and Future Directions in the Diagnosis of Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by loss of upper and lower motor neurons, resulting in progressive weakness of all voluntary muscles and eventual respiratory failure. Non-motor symptoms, such as cognitive and behavioral changes, frequently occur over the course of the disease. Considering its poor prognosis with a median survival time of 2 to 4 years and limited causal treatment options, an early diagnosis of ALS plays an essential role. In the past, diagnosis has primarily been determined by clinical findings supported by electrophysiological and laboratory measurements. To increase diagnostic accuracy, reduce diagnostic delay, optimize stratification in clinical trials and provide quantitative monitoring of disease progression and treatment responsivity, research on disease-specific and feasible fluid biomarkers, such as neurofilaments, has been intensely pursued. Advances in imaging techniques have additionally yielded diagnostic benefits. Growing perception and greater availability of genetic testing facilitate early identification of pathogenic ALS-related gene mutations, predictive testing and access to novel therapeutic agents in clinical trials addressing disease-modified therapies before the advent of the first clinical symptoms. Lately, personalized survival prediction models have been proposed to offer a more detailed disclosure of the prognosis for the patient. In this review, the established procedures and future directions in the diagnostics of ALS are summarized to serve as a practical guideline and to improve the diagnostic pathway of this burdensome disease.

[Gene Therapies in Motor Neuron Diseases ALS and SMA]

In the past, the diagnosis of motor neuron diseases such as amyotrophic lateral sclerosis (ALS) and 5q-associated spinal muscular atrophy (SMA) meant powerlessness in the face of seemingly untreatable diseases with severe motor-functional limitations and sometimes fatal courses. Recent advances in an understanding of the genetic causalities of these diseases, combined with success in the development of targeted gene therapy strategies, spell hope for effective, innovative therapeutic approaches, pioneering the ability to treat neurodegenerative diseases. While gene therapies have been approved for SMA since a few years, gene therapy research in ALS is still in clinical trials with encouraging results. This article provides an overview of the genetic background of ALS and SMA known to date and gene therapy approaches to them with a focus on therapy candidates that are in clinical trials or have already gained market approval.

Clinical heterogeneity in a family with flail arm syndrome and review of hnRNPA1-related spectrum

OBJECTIVE

Flail arm syndrome (FAS) is one of the atypical subtypes of amyotrophic lateral sclerosis (ALS). Mutations in hnRNPA1 encoding heterogeneous nuclear ribonucleoprotein (hnRNP) A1 are a rare genetic cause of ALS. Herein, marked clinical heterogeneity of FAS in a pedigree with a known hnRNPA1 variant was described to raise early awareness of the ALS variant. Furtherly, a literature review of the hnRNPA1-related spectrum was made to summarize the clinical and genetic characteristics.

METHODS

Detailed clinical evaluation, muscle pathology, and whole-exome sequencing were performed. The sequence and co-segregation of the mutation among the family members were confirmed by Sanger sequencing.

RESULTS

The great clinical variability was found in a FAS pedigree. Muscle pathology revealed a cluster distribution of angulated or rounded atrophic fibers, accompanied by significant multi-nucleus aggregation. Immunohistochemical staining showed that mutant hnRNPA1 proteins accumulated in muscle fiber cytoplasm. Exome sequencing identified a documented variant in hnRNPA1 gene c.1018C > T (p.P340S), which co-segregated with disease in the family. Besides, highly phenotypic heterogeneity was also found in other hnRNPA1-related diseases.

INTERPRETATION

We described a Chinese pedigree with hnRNPA1-related FAS, which showed significant clinical variability among the intrafamilial members. FAS is a relatively milder variant of ALS, due to the highly heterogeneous clinical spectrum, early observation is of paramount importance. In addition, the highly phenotypic heterogeneity and molecular genetic mechanism of the hnRNPA1-related spectrum are still beyond fully understood. Further, the detailed molecular mechanism underlying the clinical diversity is warranted to be explored.

Unexpected postmortem diagnoses in cases of clinically diagnosed amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a motor neuron disease that is clinically and pathologically characterized by impairment of the upper and lower motor neurons. The clinical diagnosis of ALS is not always straightforward because of the lack of specific biomarkers and clinical heterogeneity. This review presents the clinical and pathological findings of four autopsied cases that had been diagnosed with ALS before death. These cases had demonstrated definite and progressive motor neuron signs and symptoms, whereas postmortem assessment revealed miscellaneous disorders, including fungal infection, paraneoplastic syndrome, and amyloidosis. Importantly, nonmotor neuron signs and symptoms, including seizures, extra-pyramidal signs, ocular movement disorders, sensory disturbance, and dysautonomia, had also been documented during the disease course of the cases in the present study. The ALS-unlike symptoms were indicative of the "true" diagnosis in each case when those symptoms were isolated from motor neuron signs/symptoms.

Involvement of cortico-efferent tracts in flail arm syndrome: a tract-of-interest-based DTI study

Background

Flail arm syndrome is a restricted phenotype of motor neuron disease that is characterized by progressive, predominantly proximal weakness and atrophy of the upper limbs.

Objective

The study was designed to investigate specific white matter alterations in diffusion tensor imaging (DTI) data from flail arm syndrome patients using a hypothesis-guided tract-of-interest-based approach to identify in vivo microstructural changes according to a neuropathologically defined amyotrophic lateral sclerosis (ALS)-related pathology of the cortico-efferent tracts.

Methods

DTI-based white matter mapping was performed both by an unbiased voxel-wise statistical comparison and by a hypothesis-guided tract-wise analysis of fractional anisotropy (FA) maps according to the neuropathological ALS-propagation pattern for 43 flail arm syndrome patients vs 43 ‘classical’ ALS patients vs 40 matched controls.

Results

The analysis of white matter integrity demonstrated regional FA reductions for the flail arm syndrome group predominantly along the CST. In the tract-specific analysis according to the proposed sequential cerebral pathology pattern of ALS, the flail arm syndrome patients showed significant alterations of the specific tract systems that were identical to ‘classical’ ALS if compared to controls.

Conclusions

The DTI study including the tract-of-interest-based analysis showed a microstructural involvement pattern in the brains of flail arm syndrome patients, supporting the hypothesis that flail arm syndrome is a phenotypical variant of ALS.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00415-021-10854-6.

Confirmation of early non-bulbar onset of amyotrophic lateral sclerosis in Spanish league soccer players

OBJECTIVE

Sports-related activity has been proposed as a risk factor for ALS, particularly among professionals playing American football and soccer, with a reported prevalence between two and forty times higher than the general population. Early onset (by two decades) was described among Italian soccer players as early as 2005. This study aims to characterise the phenotype of seven Spanish retired professional and semi-professional soccer players.

METHODS

The cases were identified using the following sources: (i) personal archives from a leading ALS Unit, (ii) PubMed and specialised websites, and (iii) self-reports of patients in the media. Age and site of onset, survival time, history of trauma, playing position and time between retirement and first symptoms were investigated for soccer players in the Spanish league diagnosed between 2000 and 2020.

RESULTS

Seven ALS cases were identified. The mean age at onset was 41.5 years (SD 9.2, median 45.5, range 31.5-51.2). Onset was bulbar in one individual, while six experienced spinal onset. Three patients had the flail arm syndrome variant. Two cases were goalkeepers, two defenders and three midfielders. Four had a history of trauma (two serious). Survival time for the two deceased patients was 71.8 months. Mean time between retirement and first symptoms was 9.4 years (SD 8.0, median 15.2, range 0.1-17.5).

CONCLUSIONS

Our study has the largest sample size of non-Italian league soccer professionals and semi-professionals, and our results corroborate early onset (by 23.7 years). Unlike the Italian cohorts, bulbar onset is rare, and upper limb onset is most common.

Phenotypic variability in amyotrophic lateral sclerosis

Clinically, ALS phenotypes depend on the areas of the body that are affected, the different degrees of involvement of upper and lower motor neurons, the degrees of involvement of other systems, particularly cognition and behavior, and rates of progression. Phenotypic variability of ALS is characteristic and can be declined on the distribution of motor manifestations but also on the presence of extra-motor signs present in a variable manner in ALS patients. Neuropathologically, ALS is defined by the loss of UMN and LMN and the presence of two representative motor neuronal cytoplasmic inclusions, Bunina bodies and 43kDa Transactivation Response DNA Binding Protein (TDP-43) - positive cytoplasmic inclusions. The distribution of cytopathology and neuronal loss in patients is variable and this variability is directly related to phenotypic variability. Key regulators of phenotypic variability in ALS have not been determined. The functional decrement of TDP-43, and region-specific neuronal susceptibility to ALS, may be involved. Due to the selective vulnerability among different neuronal systems, lesions are multicentric, region-oriented, and progress at different rates. They may vary from patient to patient, which may be linked to the clinicopathological variability across patients.

Gender analysis of 'man-in-the-barrel' syndrome: is 'person-in-the-barrel' a more adequate term?

BACKGROUND AND PURPOSE

Gender bias is a known issue in healthcare and academia. We analysed the gender of patients reported in the literature with 'man-in-the-barrel' syndrome or equivalent semiological terms.

METHODS

A search in the PubMed database was conducted using the terms 'man-in-the-barrel', 'person-in-the-barrel', 'woman-in-the-barrel', 'brachial diplegia', 'flail arm' and 'cruciate paralysis'. All articles published between 1969 and 2020 containing a detailed description compatible with the original description of man-in-the-barrel syndrome were included.

RESULTS

Ninety-five patients with a clinical picture compatible with man-in-the-barrel syndrome were included. Up to 33% of patients were female. Overall, the proportion of female patients with man-in-the-barrel syndrome was 25%.

DISCUSSION AND CONCLUSIONS

The term man-in-the-barrel may disenfranchise up to a third of women presenting with brachial diplegia with undesirable consequences. We propose a gender-neutral alternative such as 'person-in-the-barrel'.

What do we know about the variability in survival of patients with amyotrophic lateral sclerosis?

INTRODUCTION

ALS is a fatal neurodegenerative disease. However, patients show variability in the length of survival after symptom onset. Understanding the mechanisms of long survival could lead to possible avenues for therapy.

AREAS COVERED

This review surveys the reported length of survival in ALS, the clinical features that predict survival in individual patients, and possible factors, particularly genetic factors, that could cause short or long survival. The authors also speculate on possible mechanisms.

EXPERT OPINION

a small number of known factors can explain some variability in ALS survival. However, other disease-modifying factors likely exist. Factors that alter motor neurone vulnerability and immune, metabolic, and muscle function could affect survival by modulating the disease process. Knowing these factors could lead to interventions to change the course of the disease. The authors suggest a broad approach is needed to quantify the proportion of variation survival attributable to genetic and non-genetic factors and to identify and estimate the effect size of specific factors. Studies of this nature could not only identify novel avenues for therapeutic research but also play an important role in clinical trial design and personalized medicine.

Phenotypic variability and its pathological basis in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is characterized by its inherent clinicopathological variability. The concurrence of upper and lower motor neuron signs is a common feature in the majority of patients with ALS. However, some patients manifest an atypical clinical course, with only upper or lower motor neuron signs, or various extra-motor symptoms including cognitive dysfunction, parkinsonism, autonomic dysfunction, or ophthalmoparesis. This variability indicates different manifestations of ALS and is reflected by ALS pathology spreading into the central nervous system. The presence of cytoplasmic inclusions positive for transactivation response DNA-binding protein 43 kDa (TDP-43) is a key feature in ALS. Loss of TDP-43 from the nucleus and its subsequent aggregation in the cytoplasm may occur in susceptible regions and may be associated with neuronal loss. However, in some regions, there is no apparent neuronal loss while TDP-43 accumulation is evident; in contrast, in other regions, neuronal loss is apparent without any evidence of TDP-43 accumulation. Therefore, in addition to TDP-43 dysfunction, underlying region-specific cellular vulnerability may exist in the upper and lower motor neurons and frontotemporal system in patients with ALS. The microscopic discrepancy and selective vulnerability may be linked to the macroscopic propensities of the sites of onset, and may also determine the direction and rate of progression of the lesions. Thus, there may be multicentric sites of onset, region-oriented disease development, and different speeds of disease progression across patients with ALS. ALS lesions occur in motor-related areas but may spread to neighboring areas. However, since lesions may spread in a discontinuous manner, and the dynamics of disease propagation have not been able to be identified, it remains controversial whether the stepwise appearance of TDP-43-positive inclusions is based on direct cell-to-cell protein propagation. Further understanding of the phenotypic variability of ALS and its pathological basis may serve as a guide for investigating the underlying pathogenesis of ALS.

Flail arm syndrome patients exhibit profound abnormalities in nerve conduction: an electromyography study

Flail arm syndrome (FAS) is a rare degenerative disease of the nervous system and a variant of amyotrophic lateral sclerosis (ALS). In the current study, we sought to further delineate electromyographic changes in sensory and motor conduction of the median nerve in four FAS patients and also described one representative case of FAS in a 63-year old Chinese male patient who was admitted because of aggravating limb myasthenia for three months. Electromyography showed that FAS patients exhibited variable electromyographic changes in sensory conduction of the median nerve. Abnormal conduction velocity of the sensory nerve in bilateral median nerves was observed in one patient but normal in two other patients. Two patients had a marked reduction in median sensory nerve action potential amplitude. In addition, one patient showed significant reduction in the conduction velocity and motor nerve action potential amplitude. The latency of motor conduction of bilateral median nerves was markedly prolonged. Furthermore, the incidence rate of the F wave in the right median nerve ranged from 5% to 100%. Furthermore, all four patients exhibited abnormalities in needle electromyography in at least three regions of the four regions examined with massive denervations in large and widened motor units and diminished recruitment of motor units, indicating the simultaneous presence of both acute denervation and chronic nerve regeneration. In conclusion, this is the first detailed study of electromyographic changes in FAS and the findings help improve clinicians' understanding of this disease and differentiating the diagnoses of FAS from ALS.

Twelve-month duration as an appropriate criterion for flail arm syndrome

Objectives: To analyze the clinical features of flail arm syndrome (FAS) in a large Chinese clinic-based cohort, and to discuss whether it is proper to use a course of 12 months from symptoms onset as the criterion for FAS. Methods: This cohort study included patients with FAS or upper-limb-onset amyotrophic lateral sclerosis (UL-ALS) who visited Peking University Third Hospital between 2003 and 2013. Patients with FAS were diagnosed according to Wijesekera's definition, and patients fulfilling all the diagnostic criteria of FAS except that the course of disease was less than 12 months were defined as "FAS-type ALS". Group differences were analyzed using parametric and nonparametric tests as appropriate. Survival was analyzed using the Kaplan-Meier method and a Cox regression model. Results: One thousand nine hundred and thirty-five patients with ALS were recruited in the database, including 131 patients with FAS or FAS-type ALS and 767 with UL-ALS. The prognosis of FAS was significantly better than that of UL-ALS (p = 0.024) and FAS-type ALS (p < 0.0005), and the survival of patients with FAS-type ALS was worse than that of UL-ALS (p = 0.002). The difference in survival between those with proximal FAS (pFAS) and distal FAS (dFAS) (p = 0.188) was not significant. Conclusion: Since the prognosis of FAS-type ALS was significantly worse than that of FAS, our data suggest that a FAS subphenotype can be established after 12 months from first symptoms. It is important to note that FAS-type ALS phenotype may carry a worse prognosis than that of patients with UL-ALS.

Atypical Motor Neuron Disease variants: Still a diagnostic challenge in Neurology

Motor neuron disease (MND) represents a wide and heterogeneous expanding group of disorders involving the upper or lower motor neurons, mainly represented by amyotrophic lateral sclerosis (ALS), primary lateral sclerosis, progressive muscular atrophy and progressive bulbar palsy. Primary motor neuronopathies are characterized by progressive degenerative loss of anterior horn cell motoneurons (lower motor neurons) or loss of giant pyramidal Betz cells (upper motor neurons). Despite its well-known natural history, pathophysiological and clinical characteristics for the most common MND, atypical clinical presentation and neurodegenerative mechanisms are commonly observed in rare clinical entities, so-called atypical variants of MND-ALS, including flail-leg syndrome, flail-arm syndrome, facial-onset sensory and motor neuronopathy (FOSMN), finger extension weakness and downbeat nystagmus (FEWDON-MND) and long-lasting and juvenile MND-ALS. Herein, we provide a review article presenting clinical, genetic, pathophysiological and neuroimaging findings of atypical variants of MND-ALS in clinical practice.

Pregnancy 5 Years After Onset of Amyotrophic Lateral Sclerosis Symptoms: A Case Report and Review of the Literature

BACKGROUND

Pregnancy in patients with amyotrophic lateral sclerosis (ALS) is extremely rare and often results in delivery of a healthy baby when patients are in the early stages of the disease.

CASE

This report describes the case of a successful pregnancy 5 years after ALS onset. Significant worsening of weakness, unsteady balance, and dysphagia were noticed around the third trimester. A healthy child was delivered at term by planned Caesarean section. After delivery the patient developed remarkable weakness, dysphagia, and dysarthria.

CONCLUSION

A literature search found 22 cases through PubMed and Ovid, with key words "amyotrophic lateral sclerosis" and "pregnancy." Both slow progression and rapid progression of ALS during pregnancy have been reported. Worsening of symptoms seems to be common, but little is still known about the influence of pregnancy on ALS onset and progression.

Unexpected prion phenotypes in experimentally transfused animals: predictive models for humans?

The recently reevaluated high prevalence of healthy carriers (1/2,000 in UK) of variant Creutzfeldt-Jakob Disease (v-CJD), whose blood might be infectious, suggests that the evolution of this prion disease might not be under full control as expected. After experimental transfusion of macaques and conventional mice with blood derived from v-CJD exposed (human and animal) individuals, we confirmed in these both models the transmissibility of v-CJD, but we also observed unexpected neurological syndromes transmissible by transfusion: despite their prion etiology confirmed through transmission experiments, these original cases would escape classical prion diagnosis, notably in the absence of detectable abnormal PrP with current techniques. It is noteworthy that macaques developed an original, yet undescribed myelopathic syndrome associating demyelination and pseudo-necrotic lesions of spinal cord, brainstem and optical tract without affecting encephalon, which is rather evocative of spinal cord disease than prion disease in human medicine. These observations strongly suggest that the spectrum of human prion diseases may extend the current field restricted to the phenotypes associated to protease-resistant PrP, and may notably include spinal cord diseases.

Experimental transfusion of variant CJD-infected blood reveals previously uncharacterised prion disorder in mice and macaque

Exposure of human populations to bovine spongiform encephalopathy through contaminated food has resulted in <250 cases of variant Creutzfeldt-Jakob disease (vCJD). However, more than 99% of vCJD infections could have remained silent suggesting a long-term risk of secondary transmission particularly through blood. Here, we present experimental evidence that transfusion in mice and non-human primates of blood products from symptomatic and non-symptomatic infected donors induces not only vCJD, but also a different class of neurological impairments. These impairments can all be retransmitted to mice with a pathognomonic accumulation of abnormal prion protein, thus expanding the spectrum of known prion diseases. Our findings suggest that the intravenous route promotes propagation of masked prion variants according to different mechanisms involved in peripheral replication.

Quantitative FLAIR MRI in Amyotrophic Lateral Sclerosis

RATIONALE AND OBJECTIVES

T2-weighted magnetic resonance imaging (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 fluid-attenuated inversion recovery (FLAIR) MRI intensity across a range of ALS phenotypes.

MATERIALS AND METHODS

Thirty-three classical ALS patients, 10 with a flail arm presentation, and six with primary lateral sclerosis underwent MRI at 3 Tesla. Comparisons of quantitative FLAIR intensity in the CST and corpus callosum were made between 21 healthy controls and within patient phenotypic subgroups, some of whom were studied longitudinally.

RESULTS

Mean FLAIR intensity was greater in patient groups. The cerebral peduncle intensity provided the strongest subgroup 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.

CONCLUSIONS

FLAIR MRI encodes quantifiable information of potential diagnostic, stratification, and monitoring value.

Chiari type I malformation with cervicothoracic syringomyelia subterfuge as flail arm syndrome

Chiari type I malformation with cervicothoracic syringomyelia although very common in clinical practice usually in children can progress slowly and mimic muscular dystrophies in adulthood. We present a rare adult case of Chiari type I malformation with cervicothoracic syringomyelia subterfuge as Flail arm syndrome. A 44-year-old man was diagnosed with congenital type I Chiari malformation with cervicothoracic syringomyelia about 21 years ago without surgery. His health status deteriorated over the years until 21 days prior to presentation when he had severe pain in the right knee. In his upper limbs, he had bilateral corresponding severe weakness of 0/5 proximal strength and 0/5 strength in his distal muscles. Magnetic resonance imaging (MRI) revealed an enlargement of the spinal cord from C1-C4 level with a mass that appeared hypo-dense on T1 and hyperdense on T2. Syringomyelia is a potentially serious neurologic condition that can mimic other neuromuscular disorders. Early detection and diagnosis with MRI is crucial to avoid irreversible neurological complications. We suggest that whether asymptomatic or symptomatic, decompressive surgery should be carried out to allow for free flow of cerebrospinal fluid thereby improving the quality of life for the patient.

Amyotrophic lateral sclerosis: moving towards a new classification system

Amyotrophic lateral sclerosis is a progressive adult-onset neurodegenerative disease that primarily affects upper and lower motor neurons, but also frontotemporal and other regions of the brain. The extent to which each neuronal population is affected varies between individuals. The subsequent patterns of disease progression form the basis of diagnostic criteria and phenotypic classification systems, with considerable overlap in the clinical terms used. This overlap can lead to confusion between diagnosis and phenotype. Formal classification systems such as the El Escorial criteria and the International Classification of Diseases are systematic approaches but they omit features that are important in clinical management, such as rate of progression, genetic basis, or functional effect. Therefore, many neurologists use informal classification approaches that might not be systematic, and could include, for example, anatomical descriptions such as flail-arm syndrome. A new strategy is needed to combine the benefits of a systematic approach to classification with the rich and varied phenotypic descriptions used in clinical practice.

Motor neuron disease: biomarker development for an expanding cerebral syndrome

Descriptions of motor neuron disease (MND) documented more than a century ago remain instantly recognisable to the physician. The muscle weakness, typically with signs of upper and lower motor neuron dysfunction, is uniquely relentless. Over the last 30 years, a wider cerebral pathology has emerged, despite the lack of overt cognitive impairment in the majority of patients. From the initial linkage of a small number of cases to mutations in SOD1, diverse cellular pathways have been implicated in pathogenesis. An increasingly complex clinical heterogeneity has emerged around a significant variability in survival. Defining a cellular signature of aggregated TDP-43 common to nearly all MND and a large proportion of frontotemporal dementia (FTD), has placed MND alongside more traditional cerebral neurodegeneration. With new genetic causes, most notably a hexanucleotide expansion in C9orf72 associated with both MND and FTD, the development of biomarkers against which to test therapeutic candidates is a priority.

Motor neuron disease: biomarker development for an expanding cerebral syndrome

Descriptions of motor neuron disease (MND) documented more than a century ago remain instantly recognisable to the physician. The muscle weakness, typically with signs of upper and lower motor neuron dysfunction, is uniquely relentless. Over the last 30 years, a wider cerebral pathology has emerged, despite the lack of overt cognitive impairment in the majority of patients. From the initial linkage of a small number of cases to mutations in SOD1, diverse cellular pathways have been implicated in pathogenesis. An increasingly complex clinical heterogeneity has emerged around a significant variability in survival. Defining a cellular signature of aggregated TDP-43 common to nearly all MND and a large proportion of frontotemporal dementia (FTD), has placed MND alongside more traditional cerebral neurodegeneration. With new genetic causes, most notably a hexanucleotide expansion in C9orf72 associated with both MND and FTD, the development of biomarkers against which to test therapeutic candidates is a priority.

Clinical features and differential diagnosis of flail arm syndrome

Flail arm syndrome (FAS) is a variant of motor neuron disease which is characterized by progressive, predominantly proximal weakness and atrophy of the upper limbs (UL). Because of its heterogeneous presentation and its relatively slow progression, differential diagnosis may be difficult particularly in the early stages of the disease. The aim of this study was to investigate typical clinical features of FAS with special regard to initial symptoms and differences to classical Charcot type amyotrophic lateral sclerosis (ALS). We retrospectively evaluated the clinical features of 42 FAS patients who were seen in the outpatient clinics of 4 German centers between 2000 and 2010 and compared them to 146 sex-matched control patients with classical spinal-onset ALS. FAS patients were younger (54.7 ± 9.3 versus 59.4 ± 12.2 years), male patients were predominantly affected (3.8:1 versus 1.9:1), and FAS patients showed a prolonged survival (53 versus 33 months) compared to classical ALS patients. The share of patients with initial misdiagnoses was 54.8% and led to ineffective therapy with immunoglobulins in 26%. Initial symptoms were most frequently present either in distal muscles only or in both proximal and distal muscle groups combined (76%) and showed an asymmetric distribution pattern in the majority of cases (76%). Although all patients developed symmetric and predominantly proximal UL weakness and atrophy during the course of their disease, we found that most patients initially showed asymmetric and predominantly distal distribution of symptoms. This may contribute to difficulties in differential diagnosis and to ineffective treatment regimes.

Flail arm syndrome with cytoplasmic vacuoles in remaining anterior horn motor neurons: A peculiar variant of amyotrophic lateral sclerosis

Flail arm (FA) syndrome, a minor subtype of amyotrophic lateral sclerosis (ALS), is characterized by progressive weakness and upper girdle wasting, but the associated pathological changes remain unclear. A 59-year-old man was admitted to our hospital with a 3-year history of upper girdle weakness. Bulbar symptom and gait disturbance gradually developed, and he was clinically diagnosed with FA syndrome. After a 10-year disease course, he died of pulmonary adenocarcinoma. Neuropathological examination revealed severe motor neuronal loss in the brain stem and anterior horn of the cervical spinal cord with bilateral pyramidal tract degeneration. The histological findings were consistent with typical ALS, including Bunina bodies and Lewy body-like and skein-like inclusions. Cytoplasmic vacuoles were found in the remaining anterior horn motor neurons of the lumbar spinal cord. This is a unique autopsy case with a long-standing clinical course that suggests that FA syndrome is an atypical form of ALS.

Sporadic lower motor neuron disease with a snake eyes appearance on the cervical anterior horns by MRI

OBJECTIVE

Lower motor neuron disease (LMND) is the term generally used to describe diseases in which only lower motor neuron signs are detected. A snake eyes appearance on magnetic resonance imaging (MRI) is associated with a wide spectrum of neurological conditions including LMND. The author reports on three unique LMND patients with upper limb muscle weakness and atrophy who show a snake eyes appearance by MRI.

PATIENTS AND METHODS

The patients were aged 18, 40 and 52 years, respectively, at the onset of the disease and had a longstanding clinical course (more than 10 years for two patients and 8 years for one patient). They were followed up for more than 6 years.

RESULTS

Clinical manifestations were characterized by (1) longstanding slow progression or delayed spontaneous arrest of asymmetric lower motor neuron signs localized exclusively in the upper extremities with unilateral predominance and distal or proximal preponderance; (2) the absence of upper motor neuron signs, bulbar signs, sensory disturbances and respiratory involvement; (3) a snake eyes appearance on the anterior horns of the cervical cord over more than 3 vertebrae by axial T2-weighted MRI and a longitudinal linear-shaped T2-signal hyperintensity by sagittal MRI; (4) neurogenic change with fasciculation and denervation potentials (fibrillation and a positive sharp wave) confined to the affected muscles by needle electromyogram; and (5) normal cerebrospinal fluid and a normal creatine kinase level. These cases did not fall into any existing category of LMND, such as progressive muscular atrophy, flail arm syndrome or Hirayama disease.

CONCLUSIONS

These patients should be classified as sporadic LMND with snake eyes on MRI with a relatively benign prognosis.

Neurophysiological Differences between Flail Arm Syndrome and Amyotrophic Lateral Sclerosis

There are many clinical features of flail arm syndrome (FAS) that are different from amyotrophic lateral sclerosis (ALS), suggesting they are probably different entities. Studies on electrophysiological differences between them are limited at present, and still inconclusive. Therefore, we aimed to find clinical and neurophysiological differences between FAS and ALS. Eighteen healthy control subjects, six FAS patients and forty-one ALS patients were recruited. The upper motor neuron signs (UMNS), split-hand index (SI), resting motor threshold (RMT), central motor conduction time (CMCT) were evaluated and compared. There was no obvious upper motor neuron signs in FAS. The SI and RMT level in FAS was similar to control subjects, but significantly lower than that of in ALS. Compared with control group, the RMT and SI in ALS group were both significantly increased to higher level. However, no significant difference of CMCT was found between any two of these three groups. The differences in clinical and neurophysiological findings between FAS and ALS, argue against they are the same disease entity. Since there was no obvious UMNS, no split-hand phenomenon, and no obvious changes of RMT and CMCT in FAS patients, the development of FAS might be probably not originated from motor cortex.

The expanding syndrome of amyotrophic lateral sclerosis: a clinical and molecular odyssey

Recent advances in understanding amyotrophic lateral sclerosis (ALS) have delivered new questions. Disappointingly, the initial enthusiasm for transgenic mouse models of the disease has not been followed by rapid advances in therapy or prevention. Monogenic models may have inadvertently masked the true complexity of the human disease. ALS has evolved into a multisystem disorder, involving a final common pathway accessible via multiple upstream aetiological tributaries. Nonetheless, there is a common clinical core to ALS, as clear today as it was to Charcot and others. We stress the continuing relevance of clinical observations amid the increasing molecular complexity of ALS.

Challenges in the Understanding and Treatment of Amyotrophic Lateral Sclerosis/Motor Neuron Disease

With the acceleration in our understanding of ALS and the related motor neuron disease has come even greater challenges in reconciling all of the proposed pathogenic mechanisms and how this will translate into impactful treatments. Fundamental issues such as diagnostic definition(s) of the disease spectrum, relevant biomarkers, the impact of multiple novel genetic mutations and the significant effect of symptomatic treatments on disease progression are all areas of active investigation. In this review, we will focus on these key issues and highlight the challenges that confront both clinicians and basic science researchers.

The phenotypic variability of amyotrophic lateral sclerosis

Classic textbook neurology teaches that amyotrophic lateral sclerosis (ALS) is a degenerative disease that selectively affects upper and lower motor neurons and is fatal 3-5 years after onset--a description which suggests that the clinical presentation of ALS is very homogenous. However, clinical and postmortem observations, as well as genetic studies, demonstrate that there is considerable variability in the phenotypic expression of ALS. Here, we review the phenotypic variability of ALS and how it is reflected in familial and sporadic ALS, in the degree of upper and lower motor neuron involvement, in motor and extramotor involvement, and in the spectrum of ALS and frontotemporal dementia. Furthermore, we discuss some unusual clinical characteristics regarding presentation, age at onset and disease progression. Finally, we address the importance of this variability for understanding the pathogenesis of ALS and for the development of therapeutic strategies.

Comparison between Flail Arm Syndrome and Upper Limb Onset Amyotrophic Lateral Sclerosis: Clinical Features and Electromyographic Findings

Flail arm syndrome (FAS), an atypical presentation of amyotrophic lateral sclerosis (ALS), is characterized by progressive, predominantly proximal, weakness of upper limbs, without involvement of the lower limb, bulbar, or respiratory muscles. When encountering a patient who presents with this symptomatic profile, possible diagnoses include upper limb onset ALS (UL-ALS), and FAS. The lack of information regarding FAS may make differential diagnosis between FAS and UL-ALS difficult in clinical settings. The aim of this study was to compare clinical and electromyographic findings from patients diagnosed with FAS with those from patients diagnosed with UL-ALS. To accomplish this, 18 patients with FAS and 56 patients with UL-ALS were examined. Significant differences were observed between the 2 groups pertaining to the rate of fasciculation, patterns of predominantly affected muscles, and the Medical Research Council scale of the weakest muscle. The presence of upper motor neuron signs and lower motor neuron involvement evidenced through electromyography showed no significant between-group differences.

Assessment of disease progression and functional benefit in neurodegenerative disease: can we tell the difference?

Therapeutic strategies for neurodegenerative diseases include modalities intended to modulate disease progression as well as those whose intent is to improve or maintain functional capacity. As the search for pharmacodynamic markers has proved elusive, treatment outcomes most commonly reflect patient function. As a result, even when clinical trials show a beneficial effect, the underlying etiology of that benefit can be difficult to determine. This review summarizes recent trials in ALS and Parkinson's disease, with the goal of increasing understanding of how the choice of outcome measures influences what can be concluded from the results. Although most ALS trials have been negative in recent years, outcomes are reviewed in terms of potential conclusions that could have been drawn. Functional benefit has been established in a number of recent trials; however, the outcomes used have lead to uncertainty as to whether specific agents modify disease or alter function. In the absence of specific markers sensitive to alteration of disease specific pathways, the distinction between agents that alter underlying disease versus those that affect function may depend on underlying hypotheses rather than clinical trial results.

[Diagnosis and management of cervical spondylosis]

Cervical spondylosis, which can present as radiculopathy and myelopathy, is common in people over the age of 50. Since evidence of radiological spondylotic change is frequently found in many asymptomatic adults, it is necessary to assess whether neurological symptoms result from cervical spondylosis or other neurological disorders. In order to avoid misdiagnosis, it is important to compare the levels of the lesions shown on imaging with the clinical findings. Differential diagnosis between amyotrophic lateral sclerosis and cervical spondylotic myelopathy is an issue of major clinical importance. Though the course of disease development and the ultimate prognosis for patients with cervical spondylosis is highly variable and extremely difficult to predict, many patients experience a relatively benign form of the disease.

Mimics and chameleons in motor neurone disease

The progression of motor neurone disease (MND) is currently irreversible, and the grave implications of diagnosis naturally fuels concern among neurologists over missing a potential mimic disorder. There is no diagnostic test for MND but in reality there are few plausible mimics in routine clinical practice. In the presence of a progressive pure motor disorder, signs such as florid fasciculations, bilateral tongue wasting, the ‘split hand’, head drop, emotionality, and cognitive or behavioural impairment carry high positive predictive value. MND is clinically heterogeneous, however, with some important chameleon-like presentations and considerable variation in clinical course. Lack of confidence about the scope of such variation, or an approach to diagnosis emphasising investigations over clinical common sense, has the potential to exacerbate diagnostic delay in MND and impede timely planning of the care which is essential to maximising quality of life.

White matter pathology in ALS and lower motor neuron ALS variants: a diffusion tensor imaging study using tract-based spatial statistics

The aim of this work was to investigate white-matter microstructural changes within and outside the corticospinal tract in classical amyotrophic lateral sclerosis (ALS) and in lower motor neuron (LMN) ALS variants by means of diffusion tensor imaging (DTI). We investigated 22 ALS patients and 21 age-matched controls utilizing a whole-brain approach with a 1.5-T scanner for DTI. The patient group was comprised of 15 classical ALS- and seven LMN ALS-variant patients (progressive muscular atrophy, flail arm and flail leg syndrome). Disease severity was measured by the revised version of the functional rating scale. White matter fractional anisotropy (FA) was assessed using tract-based spatial statistics (TBSS) and a region of interest (ROI) approach. We found significant FA reductions in motor and extra-motor cerebral fiber tracts in classical ALS and in the LMN ALS-variant patients compared to controls. The voxel-based TBSS results were confirmed by the ROI findings. The white matter damage correlated with the disease severity in the patient group and was found in a similar distribution, but to a lesser extent, among the LMN ALS-variant subgroup. ALS and LMN ALS variants are multisystem degenerations. DTI shows the potential to determine an earlier diagnosis, particularly in LMN ALS variants. The statistically identical findings of white matter lesions in classical ALS and LMN variants as ascertained by DTI further underline that these variants should be regarded as part of the ALS spectrum.

Effects of gender in amyotrophic lateral sclerosis

BACKGROUND

There is evidence that amyotrophic lateral sclerosis (ALS), also known as motor neuron disease (MND), is more common in men than in women and that gender influences the clinical features of the disease. The causes of this are unknown.

OBJECTIVE

This review examines the gender differences that are found in ALS and postulates reasons for these differences.

METHODS

A literature review of PubMed (with no date limits) was performed to find information about gender differences in the incidence, prevalence, and clinical features of ALS, using the search terms ALS or MND and gender or sex, ALS prevalence, and SOD1 mice and gender. Articles were reviewed for information about gender differences, together with other articles that were already known to the authors.

RESULTS

The incidence and prevalence of ALS are greater in men than in women. This gender difference is seen in large studies that included all ALS patients (sporadic and familial), but is not seen when familial ALS is studied independently. Men predominate in the younger age groups of patients with ALS. Sporadic ALS has different clinical features in men and women, with men having a greater likelihood of onset in the spinal regions, and women tending to have onset in the bulbar region. Gender appears to have no clear effect on survival. In animals with superoxide dismutase 1 (sod1) mutations, sex does affect the clinical course of disease, with earlier onset in males. Possible reasons for the differences in ALS between men and women include different exposures to environmental toxins, different biological responses to exogenous toxins, and possibly underlying differences between the male and female nervous systems and different abilities to repair damage.

CONCLUSIONS

There is a complex interaction between gender and clinical phenotypes in ALS. Understanding the causes of the gender differences could give clues to processes that modify the disease.

Pattern of spread and prognosis in lower limb-onset ALS

Our objective was to establish the pattern of spread in lower limb-onset ALS (contra- versus ipsi-lateral) and its contribution to prognosis within a multivariate model. Pattern of spread was established in 109 sporadic ALS patients with lower limb-onset, prospectively recorded in Oxford and Sheffield tertiary clinics from 2001 to 2008. Survival analysis was by univariate Kaplan-Meier log-rank and multivariate Cox proportional hazards. Variables studied were time to next limb progression, site of next progression, age at symptom onset, gender, diagnostic latency and use of riluzole. Initial progression was either to the contralateral leg (76%) or ipsilateral arm (24%). Factors independently affecting survival were time to next limb progression, age at symptom onset, and diagnostic latency. Time to progression as a prognostic factor was independent of initial direction of spread. In a regression analysis of the deceased, overall survival from symptom onset approximated to two years plus the time interval for initial spread. In conclusion, rate of progression in lower limb-onset ALS is not influenced by whether initial spread is to the contralateral limb or ipsilateral arm. The time interval to this initial spread is a powerful factor in predicting overall survival, and could be used to facilitate decision-making and effective care planning.

Lockhart Clarke's contribution to the description of amyotrophic lateral sclerosis

The definition of the clinicopathological entity of amyotrophic lateral sclerosis evolved over half a century. Although the definitive term amyotrophic lateral sclerosis that acknowledged both upper and lower motor neuron involvement was attributed to Jean-Martin Charcot in 1874, his initial case was published nearly a decade earlier; and it is accepted that, from at least the 1830s, several others (including Charles Bell, François-Amilcar Aran and Jean Cruveilhier) had already recognized a progressive lower motor neuron-only syndrome within a broader, clinically-defined group of disorders, termed progressive muscular atrophy. Although William Gowers first grouped the three phenotypes of amyotrophic lateral sclerosis, progressive muscular atrophy and progressive bulbar palsy together as part of the same syndrome, the term motor neuron disease, as an over-arching label, was not suggested until nearly a century later by W. Russell Brain. Augustus Jacob Lockhart Clarke (1817-80) is best known for his descriptions of spinal cord anatomy. However, in two detailed case reports from the 1860s, he carried out rigorous post-mortem neuropathological studies of what appear to be classical cases of amyotrophic lateral sclerosis. Furthermore, he recognized the additional involvement of the corticospinal tracts that distinguished this from progressive muscular atrophy. Several aspects of the exquisite clinical histories documented as part of both studies, one by Charles Bland Radcliffe, resonate with contemporary debates concerning the evolution of disease in amyotrophic lateral sclerosis. These 'past masters' still have much to teach us.