The fragile X tremor ataxia syndrome in the differential diagnosis of multiple system atrophy: data from the EMSA Study Group

Parkinsonism in complex neurogenetic disorders: lessons from hereditary dementias, adult-onset ataxias and spastic paraplegias

Parkinsonism is a syndrome characterized by bradykinesia in combination with either rest tremor, rigidity, or both. These features are the cardinal manifestations of Parkinson's disease, the most common cause of parkinsonism, and atypical parkinsonian disorders. However, parkinsonism can be a manifestation of complex neurological and neurodegenerative genetically determined disorders, which have a vast and heterogeneous motor and non-motor phenotypic features. Hereditary dementias, adult-onset ataxias and spastic paraplegias represent only few of this vast group of neurogenetic diseases. This review will provide an overview of parkinsonism's clinical features within adult-onset neurogenetic diseases which a neurologist could face with. Understanding parkinsonism and its characteristics in the context of the aforementioned neurological conditions may provide insights into pathophysiological mechanisms and have important clinical implications, including diagnostic and therapeutic aspects.

Ataxias: Hereditary, Acquired, and Reversible Etiologies

A variety of etiologies can cause cerebellar dysfunction, leading to ataxia symptoms. Therefore, the accurate diagnosis of the cause for cerebellar ataxia can be challenging. A step-wise investigation will reveal underlying causes, including nutritional, toxin, immune-mediated, genetic, and degenerative disorders. Recent advances in genetics have identified new genes for both autosomal dominant and autosomal recessive ataxias, and new therapies are on the horizon for targeting specific biological pathways. New diagnostic criteria for degenerative ataxias have been proposed, specifically for multiple system atrophy, which will have a broad impact on the future clinical research in ataxia. In this article, we aim to provide a review focus on symptoms, laboratory testing, neuroimaging, and genetic testing for the diagnosis of cerebellar ataxia causes, with a special emphasis on recent advances. Strategies for the management of cerebellar ataxia is also discussed.

Screening for the FMR1 premutation in Greek patients with late-onset movement disorders

Fragile X-associated tremor/ataxia syndrome (FXTAS) is a late-onset, X-linked, neurodegenerative disorder that affects premutation carriers of the FMR1 gene. FXTAS is often misdiagnosed as spinocerebellar ataxia (SCA) or Parkinson's disease (PD). Herein, we sought to investigate the frequency, genotypic and phenotypic profile of FXTAS in two cohorts of Greek patients with late-onset movement disorders, one with cerebellar ataxia and the other with PD. In total, 90 index patients with late-onset cerebellar ataxia and 171 with PD were selected. None of the cases had male-to-male transmission. Genetic screening for the FMR1 premutation was performed using standard methodology. The FMR1 premutation was detected in two ataxia patients (2.2%) and two PD patients (1.2%). Additional clinical features in FXTAS patients from the ataxia cohort included neuropathy, mild parkinsonism, cognitive impairment and pyramidal signs. The FXTAS patients from the PD cohort had typical PD. We conclude that, in the Greek population, the FMR1 premutation is an important, albeit rare, cause of late-onset movement disorders. Routine premutation screening should be considered in SCA panel-negative late-onset ataxia cases. Directed premutation screening should be considered in all ataxia and PD cases with additional features suggestive of FXTAS. Our study highlights the importance of FMR1 genetic testing in the diagnosis of late-onset movement disorders.

The "Hot Cross Bun Sign" in Spinocerebellar Ataxia Types 2 and 7-Case Reports and Review of Literature

Background

The "hot cross bun" sign is a cruciform hyperintensity is seen on T2 weighted imaging within the pons. The sign is considered to be pathognomic for Multiple system atrophy type C. The clinical and radiological features of Multiple system atrophy type C overlap with the autosomal dominant inherited ataxias. We present a case series of 3 African patients with genetically proven Spinocerebellar Ataxia presenting with the Hot cross bun sign and a scoping review of similar studies.

Cases

We described the phenotypic and radiological presentation of genetically confirmed SCA-2 in two, and SCA-7 in one patient, with the "hot cross bun" sign.

Literature Review

We performed a scoping review on the Hot Cross Bun Sign.A total of 66 articles were retrieved. We describe the diverse aetiologies of the sign and associated phenotypic and radiological features. We review the Spinocerebellar Ataxias described with a Hot cross bun sign and make comparisons to Multiple System Atrophy Type C [Ref. 1,2].

Conclusions

To our knowledge this is the first description of an African cohort presenting with the Hot Cross Bun Sign. We expand the differential diagnosis of the Hot Cross Bun Sign.

The “hot cross bun sign” in patients with autoimmune cerebellar ataxia: A case report and literature review

Objectives

The “hot cross bun sign” (HCBs) on magnetic resonance imaging (MRI) has been initially considered specific for multiple system atrophy with cerebellar features. However, a number of other conditions have since been described, which may be associated with this imaging sign. We herein describe a patient with anti-Ri and paraneoplastic cerebellar ataxia, and review the association of the HCBs on imaging with various neurological autoimmune conditions.

Methods

We report a 40-year-old woman with anti-Ri-associated paraneoplastic neurological syndrome and breast carcinoma, in whom brain MRI revealed the HCBs late in the disease course. We also reviewed similar cases reported in the literature.

Results

The patient presented with cerebellar ataxia, polyneuropathy, and pyramidal signs. Although brain MRI was initially unremarkable, the HCBs and T2-weighted hyperintensity of the bilateral middle cerebellar peduncles were observed at later follow-up. Anti-Ri was detected in the serum and cerebrospinal fluid. Breast adenocarcinoma was confirmed via an axillary lymph node biopsy. Her symptoms partially resolved after the first corticosteroid pulse. However, subsequent immunotherapy and tumor treatments were ineffective. Four autoimmune cerebellar ataxia cases with the HCBs (two paraneoplastic and two non-paraneoplastic) were identified in the literature.

Discussion

The HCBs can be associated with paraneoplastic and non-paraneoplastic cerebellar ataxia, which may reflect neurodegeneration secondary to autoimmune injury. Thus, the HCBs should not be considered a contraindication for autoimmune cerebellar syndrome.

Frequency of FMR1 Premutation Alleles in Patients with Undiagnosed Cerebellar Ataxia and Multiple System Atrophy in the Japanese Population

Fragile X-associated tremor/ataxia syndrome (FXTAS) is an adult-onset neurodegenerative disorder caused by FMR1 premutation expansion of CGG repeats. FXTAS can be misdiagnosed with many neurodegenerative disorders manifesting with cerebellar ataxias owing to their overlapping clinical and radiological features. The frequency of the FMR1 premutation allele in Japan has not been fully determined. Herein, we aimed to determine the frequency of FMR1 premutation alleles in Japanese patients with undiagnosed cerebellar ataxia and multiple system atrophy, using repeat-primed PCR in 186 patients with adult onset of undiagnosed cerebellar ataxia and 668 patients with multiple system atrophy, to identify expanded CGG repeats as well as to detect AGG interruptions within the expanded alleles. The size of expansions was estimated using fragment length analysis of PCR products obtained by conventional PCR employing a pair of unique primers flanking the repeat sequence. We identified FMR1 premutation alleles in three male patients. One patient revealed 84 repeat units with one AGG interruption and another patient showed 103 repeat units. Both had presented with sporadic cerebellar ataxia, giving an estimated frequency of 3.7% among Japanese male patients with sporadic cerebellar ataxia with age at onset above 50 years. One patient with the clinical diagnosis of multiple system atrophy harbored 60 repeat units with four AGG interruptions. FMR1 intermediate alleles were observed in two males and one female among the multiple system atrophy patients. We found that genetic tests for FMR1 premutation should be considered in Japanese male patients with cerebellar ataxia with the age at onset above 50 years.

The role of cardiovascular autonomic failure in the differential diagnosis of α-synucleinopathies

The α-synucleinopathies comprise a group of adult-onset neurodegenerative disorders including Parkinson’s disease (PD), multiple system atrophy (MSA), dementia with Lewy bodies (DLB,) and — as a restricted non-motor form — pure autonomic failure (PAF). Neuropathologically, the α-synucleinopathies are characterized by aggregates of misfolded α-synuclein in the central and peripheral nervous system. Cardiovascular autonomic failure is a common non-motor symptom in people with PD, a key diagnostic criterion in MSA, a supportive feature for the diagnosis of DLB and disease-defining in PAF. The site of autonomic nervous system lesion differs between the α-synucleinopathies, with a predominantly central lesion pattern in MSA versus a peripheral one in PD, DLB, and PAF. In clinical practice, overlapping autonomic features often challenge the differential diagnosis among the α-synucleinopathies, but also distinguish them from related disorders, such as the tauopathies or other neurodegenerative ataxias. In this review, we discuss the differential diagnostic yield of cardiovascular autonomic failure in individuals presenting with isolated autonomic failure, parkinsonism, cognitive impairment, or cerebellar ataxia.

Parkinsonism and ataxia

Ataxia is not a common feature in Parkinson's disease. Nevertheless, some rare forms of parkinsonism have ataxia as one of the main features in their clinical picture, especially those with juvenile or early-onset. On the other side, in cerebellar degenerative diseases, parkinsonism might accompany the typical symptoms and even become predominant in some cases. Many disorders involving different neurological systems present with a movement phenomenology reflecting the underlying pattern of pathological involvement, such as neurodegeneration with brain iron accumulation, neurodegeneration associated with calcium deposition, and metabolic and mitochondrial disorders. The prototype of sporadic disorders that present with a constellation of symptoms due to the involvement of multiple Central Nervous System regions is multiple system atrophy, whose motor symptoms at onset can be cerebellar ataxia or parkinsonism. Clinical syndromes encompassing both parkinsonian and cerebellar features might represent a diagnostic challenge for neurologists. Recognizing acquired and potentially treatable causes responsible for complex movement disorders is of paramount importance, since an early diagnosis is essential to prevent permanent consequences. The present review aims to provide a pragmatic overview of the most common diseases characterized by the coexistence of cerebellar and parkinsonism features and suggests a possible diagnostic approach for both inherited and sporadic disorders. This article is part of the Special Issue "Parkinsonism across the spectrum of movement disorders and beyond" edited by Joseph Jankovic, Daniel D. Truong and Matteo Bologna.

Premutations in the FMR1 gene in Serbian patients with undetermined tremor, ataxia and parkinsonism

Introduction: Although one of the most common monogenic late-onset neurodegenerative disorders, fragile-X-associated tremor/ataxia syndrome (FXTAS) is still underdiagnosed. The aim of the present study was to estimate the frequency of premutation carriers in patients with unexplained degenerative ataxias, action tremor or parkinsonism, and action tremor with or without associated cognitive impairment.Methods: The study comprised 100 consecutive patients with the disease onset >49 years who had any form of unexplained action tremor, cerebellar ataxia, followed by parkinsonism with or without incipient dementia, and in whom the FMR1 repeats size was determined.Results: Premutation in the FMR1 was identified in two patients (2%): the first, male patient had 83 CGG repeats and the second, female patient had 32 and 58 CGG repeats.Discussion/Conclusion: FXTAS was relatively rare among older patients with unexplained ataxia and action tremor, with or without parkinsonism and/or cognitive impairment. Tremor and ataxia were major clinical features in our two patients, although parkinsonism, autonomic dysfunction and psychiatric problems might be an important part of the spectrum. Probable FXTAS should be considered in the differential diagnosis of patients with unexplained action tremor and ataxia, and undetermined parkinsonism, especially when there was a positive family history for involuntary movement disorders in other family members and/or autism spectrum disorders in younger cousins.

Ataxia as the Major Manifestation of Fragile X-Associated Tremor/Ataxia Syndrome (FXTAS): Case Series

Fragile X-associated tremor and ataxia syndrome (FXTAS) is a neurodegenerative disease developed by carriers of a premutation in the fragile X mental retardation 1 (FMR1) gene. The core clinical symptoms usually manifest in the early 60s, typically beginning with intention tremor followed by cerebellar ataxia. Ataxia can be the only symptom in approximately 20% of the patients. FXTAS has a slow progression, and patients usually experience advanced deterioration 15 to 25 years after the initial diagnosis. Common findings in brain imaging include substantial brain atrophy and white matter disease (WMD). We report three cases with an atypical clinical presentation, all presenting with gait problems as their initial manifestation and with ataxia as the dominant symptom without significant tremor, as well as a faster than usual clinical progression. Magnetic resonance imaging (MRI) was remarkable for severe brain atrophy, ventriculomegaly, thinning of the corpus callosum, and periventricular WMD. Two cases were diagnosed with definite FXTAS on the basis of clinical and radiological findings, with one individual also developing moderate dementia. Factors such as environmental exposure and general anesthesia could have contributed to their clinical deterioration. FXTAS should be considered in the differential diagnosis of patients presenting with ataxia, even in the absence of tremor, and FMR1 DNA testing should be sought in those with a family history of fragile X syndrome or premutation disorders.

Repeat expansion scanning of the NOTCH2NLC gene in patients with multiple system atrophy

OBJECTIVE

Trinucleotide GGC repeat expansion in the 5'UTR of the NOTCH2NLC gene has been recognized as the pathogenesis of neuronal intranuclear inclusion disease (NIID). Previous studies have described that some NIID patients showed clinical and pathological similarities with multiple system atrophy (MSA). This study aimed to address the possibility that GGC repeat expansion in NOTCH2NLC might be associated with some cases diagnosed as MSA.

METHODS

A total of 189 patients with probable or possible MSA were recruited to screen for GGC repeat expansion in NOTCH2NLC by repeat-primed PCR (RP-PCR). In addition, long-read sequencing (LRS) was performed for all patients with RP-PCR-positive expansion, five patients with RP-PCR-negative expansion, and five controls on the Nanopore platform. Skin biopsies were performed on two patients with GGC expansion.

RESULTS

Five of 189 patients (2.6%) were found to have GGC expansion in NOTCH2NLC. LRS results identified that the five patients had GGC expansion between 101 and 266, but five patients with RP-PCR-negative expansion and five controls had GGC expansion between 8 and 29. Besides the typical symptoms and signs of MSA, patients with GGC expansion might have longer disease duration, severe urinary retention, and prominent cognitive impairment. In the skin samples from the patients with GGC expansion, typical p62-postive but alpha-synuclein-negative intranuclear inclusions were found in fibroblasts, adipocyte and ductal epithelial cells of sweat glands.

CONCLUSION

Trinucleotide GGC repeat expansion in NOTCH2NLC could be observed in patients with clinically diagnosed MSA. Adult-onset NIID should be considered as a differential diagnosis of MSA.

The 'Hot Cross Bun' Sign Is Not Always Multiple System Atrophy: Etiologies of 11 Cases

OBJECTIVE

To clarify the specificity of the 'hot cross bun' sign (HCBS) for multiple system atrophy (MSA) in adult cerebellar ataxia or parkinsonism.

METHODS

The radiologic information systems at an academic center and affiliated veterans' hospital were queried using the keywords 'hot cross bun,' 'pontocerebellar,' 'cruciate,' 'cruciform,' 'MSA,' 'multiple system atrophy,' and 'multisystem atrophy.' Scans were reviewed by a neurologist and neuroradiologist to identify the HCBS. Subjects with the HCBS were reviewed by 2 neurologists to identify the most likely etiology of the patient's neurologic symptoms.

RESULTS

Eleven cases were identified. Etiologies included MSA (4 probable, 2 possible), hereditary cerebellar ataxia (3/11), probable dementia with Lewy bodies (1/11), and uncertain despite autopsy (1/11).

CONCLUSION

MSA was the most common etiology. However, 5 of the 11 patients did not have MSA. The most common alternate etiology was an undefined hereditary cerebellar ataxia (3/11).

SPECT Molecular Imaging in Familial Parkinson's Disease

Dopamine transporter (DAT) imaging with single-photon emission computed tomography (SPECT) is a diagnostic tool to study the integrity of the dopaminergic system in patients with parkinsonism and uncertain diagnosis. DAT SPECT enables to detect the presence of nigrostriatal deficit even in the early or pre-symptomatic stages of the disease and to quantify the DAT loss with the progression of nigrostriatal degeneration. For these reasons, DAT SPECT has been also used as a tool to study genetic conditions that are associated with parkinsonism in order to examine the degree and patterns of dopaminergic deficits that are present in at risk subjects and in affected patients carrying the mutations. Studies included subjects with sporadic mutations of common genes associated with Parkinson's disease (PD) and families with both affected patients and asymptomatic carriers. For obvious reasons, the majority of the studies have included a limited number of subjects. Therefore, because of the heterogeneity and the size of the cohorts examined, in many cases the findings can be merely descriptive and general conclusions on the patterns of dopaminergic deficit in different genetic conditions need to take into account some exceptions.

Recent advances in neuropathology, biomarkers and therapeutic approach of multiple system atrophy

Multiple system atrophy (MSA) is a progressive neurodegenerative disorder characterised by a variable combination of autonomic failure, levodopa-unresponsive parkinsonism, cerebellar ataxia and pyramidal symptoms. The pathological hallmark is the oligodendrocytic glial cytoplasmic inclusion (GCI) consisting of α-synuclein; therefore, MSA is included in the category of α-synucleinopathies. MSA has been divided into two clinicopathological subtypes: MSA with predominant parkinsonism and MSA with predominant cerebellar ataxia, which generally correlate with striatonigral degeneration and olivopontocerebellar atrophy, respectively. It is increasingly recognised, however, that clinical and pathological features of MSA are broader than previously considered.In this review, we aim to describe recent advances in neuropathology of MSA from a review of the literature and from information derived from review of nearly 200 definite MSA cases in the Mayo Clinic Brain Bank. In light of these new neuropathological findings, GCIs and neuronal cytoplasmic inclusions play an important role in clinicopathological correlates of MSA. We also focus on clinical diagnostic accuracy and differential diagnosis of MSA as well as candidate biomarkers. We also review some controversial topics in MSA. Cognitive impairment, which has been a non-supporting feature of MSA, is considered from both clinical and pathological perspectives. The cellular origin of α-synuclein in GCI and a 'prion hypothesis' are discussed. Finally, completed and ongoing clinical trials targeting disease modification, including immunotherapy, are summarised.

Fragile X-associated tremor/ataxia syndrome: phenotypic comparisons with other movement disorders

OBJECTIVE

The purpose of this paper is to review the typical cognitive and motor impairments seen in fragile X-associated tremor/ataxia syndrome (FXTAS), essential tremor (ET), Parkinson disease (PD), spinocerebellar ataxias (SCAs), multiple system atrophy (MSA), and progressive supranuclear palsy (PSP) in order to enhance diagnosis of FXTAS patients.

METHODS

We compared the cognitive and motor phenotypes of FXTAS with each of these other movement disorders. Relevant neuropathological and neuroimaging findings are also reviewed. Finally, we describe the differences in age of onset, disease severity, progression rates, and average lifespan in FXTAS compared to ET, PD, SCAs, MSA, and PSP. We conclude with a flow chart algorithm to guide the clinician in the differential diagnosis of FXTAS.

RESULTS

By comparing the cognitive and motor phenotypes of FXTAS with the phenotypes of ET, PD, SCAs, MSA, and PSP we have clarified potential symptom overlap while elucidating factors that make these disorders unique from one another. In summary, the clinician should consider a FXTAS diagnosis and testing for the Fragile X mental retardation 1 (FMR1) gene premutation if a patient over the age of 50 (1) presents with cerebellar ataxia and/or intention tremor with mild parkinsonism, (2) has the middle cerebellar peduncle (MCP) sign, global cerebellar and cerebral atrophy, and/or subcortical white matter lesions on MRI, or (3) has a family history of fragile X related disorders, intellectual disability, autism, premature ovarian failure and has neurological signs consistent with FXTAS. Peripheral neuropathy, executive function deficits, anxiety, or depression are supportive of the diagnosis.

CONCLUSIONS

Distinct profiles in the cognitive and motor domains between these movement disorders may guide practitioners in the differential diagnosis process and ultimately lead to better medical management of FXTAS patients.

Neuropsychiatry of fragile X-premutation carriers with and without fragile X-associated tremor-ataxia syndrome: implications for neuropsychology

OBJECTIVES

Clinical neuropsychologists benefit from clinical currency in recently ascertained neuropsychiatric illness, such as fragile X premutation (FXPM) disorders. The author reviewed the clinical literature through 2016 for neuropsychiatric phenotypes in FXPM disorders, including patients with fragile X-associated tremor/ataxia syndrome (FXTAS).

METHODS

A PubMed search using the search terms 'Fragile X,' 'Premutation,' 'Carriers,' 'Psychiatric,' 'Dementia,' 'Mood,' and 'Anxiety' for citations in the clinical literature through 2016 was reviewed for studies specifically examining the neuropsychiatric phenotype in FXPM patients. The relevant articles were classified according to specific neuropsychiatric syndromes, including child onset, adult onset with and without FXTAS, as well as common systemic comorbidities in FXPM patients.

RESULTS

Eighty-six articles were reviewed for the neuropsychiatric and other phenotypes in FXPM patients. The neuropsychiatric phenotype in FXPM patients is distinct from that of full mutation (Fragile X Syndrome) patients. FXTAS is associated with a specific cortical-subcortical major or mild neurocognitive disorder (NCD).

CONCLUSIONS

FXPM patients are at risk for neuropsychiatric illness. In addition, FXPM patients are at risk for other systemic conditions that should raise suspicion for FXPM-associated illnesses. Clinicians should consider a diagnosis of FXPM-associated neuropsychiatric illness when patients with specific clinical scenarios are encountered; especially in patient pedigrees consistent with a typical (often multigenerational) presentation of fragile X-associated conditions, confirmatory genetic testing should be considered. Clinical management should take into account the psychological challenges of a multigenerational genetic neuropsychiatric illness with a variable CNS and systemic clinical phenotype.

Multiple system atrophy-mimicking conditions: Diagnostic challenges

Multiple system atrophy (MSA) is a relentless progressive disorder without effective treatment. Its accurate diagnosis is important for the management of individual patients and for the development of new therapeutic strategies. However, there are many disorders which can mimic MSA (so-called 'MSA look-alikes'), and the true rate for over- or under-diagnoses of MSA is not known, especially during the early course of disease when the disease is not fully developed yet. Herein, the authors review the neurodegenerative, genetic, and immunologic conditions that can mimic MSA and thus be part of the differential diagnosis of MSA. Clinicians should be aware of these conditions and be able to differentiate them by clinical features and laboratory findings.

Multiple system atrophy: the application of genetics in understanding etiology

Classically defined phenotypically by a triad of cerebellar ataxia, parkinsonism, and autonomic dysfunction in conjunction with pyramidal signs, multiple system atrophy (MSA) is a rare and progressive neurodegenerative disease affecting an estimated 3-4 per every 100,000 individuals among adults 50-99 years of age. With a pathological hallmark of alpha-synuclein-immunoreactive glial cytoplasmic inclusions (GCIs; Papp-Lantos inclusions), MSA patients exhibit marked neurodegenerative changes in the striatonigral and/or olivopontocerebellar structures of the brain. As a member of the alpha-synucleinopathy family, which is defined by its well-demarcated alpha-synuclein-immunoreactive inclusions and aggregation, MSA's clinical presentation exhibits several overlapping features with other members including Parkinson's disease (PD) and dementia with Lewy bodies (DLB). Given the extensive fund of knowledge regarding the genetic etiology of PD revealed within the past several years, a genetic investigation of MSA is warranted. While a current genome-wide association study is underway for MSA to further clarify the role of associated genetic loci and single-nucleotide polymorphisms, several cases have presented solid preliminary evidence of a genetic etiology. Naturally, genes and variants manifesting known associations with PD (and other phenotypically similar neurodegenerative disorders), including SNCA and MAPT, have been comprehensively investigated in MSA patient cohorts. More recently variants in COQ2 have been linked to MSA in the Japanese population although this finding awaits replication. Nonetheless, significant positive associations with subsequent independent replication studies have been scarce. With very limited information regarding genetic mutations or alterations in gene dosage as a cause of MSA, the search for novel risk genes, which may be in the form of common variants or rare variants, is the logical nexus for MSA research. We believe that the application of next generation genetic methods to MSA will provide valuable insight into the underlying causes of this disease, and will be central to the identification of etiologic-based therapies.

Diagnosis and differential diagnosis of MSA: boundary issues

Because the progression of multiple system atrophy (MSA) is usually rapid and there still is no effective cause-related therapy, early and accurate diagnosis is important for the proper management of patients as well as the development of neuroprotective agents. However, despite the progression in the field of MSA research in the past few years, the diagnosis of MSA in clinical practice still relies largely on clinical features and there are limitations in terms of sensitivity and specificity, especially in the early course of the disease. Furthermore, recent pathological, clinical, and neuroimaging studies have shown that (1) MSA can present with a wider range of clinical and pathological features than previously thought, including features considered atypical for MSA; thus, MSA can be misdiagnosed as other diseases, and conversely, disorders with other etiologies and pathologies can be clinically misdiagnosed as MSA; and (2) several investigations may help to improve the diagnosis of MSA in clinical practice. These aspects should be taken into consideration when revising the current diagnostic criteria. This is especially true given that disease-modifying treatments for MSA are under investigation.

Multiple system atrophy: genetic or epigenetic?

Multiple system atrophy (MSA) is a rare, late-onset and fatal neurodegenerative disease including multisystem neurodegeneration and the formation of α-synuclein containing oligodendroglial cytoplasmic inclusions (GCIs), which present the hallmark of the disease. MSA is considered to be a sporadic disease; however certain genetic aspects have been studied during the last years in order to shed light on the largely unknown etiology and pathogenesis of the disease. Epidemiological studies focused on the possible impact of environmental factors on MSA disease development. This article gives an overview on the findings from genetic and epigenetic studies on MSA and discusses the role of genetic or epigenetic factors in disease pathogenesis.

An update on the cerebellar subtype of multiple system atrophy

Multiple system atrophy is a rare and fatal neurodegenerative disorder characterized by progressive autonomic failure, ataxia and parkinsonism in any combination. The clinical manifestations reflect central autonomic and striatonigral degeneration as well as olivopontocerebellar atrophy. Glial cytoplasmic inclusions, composed of α-synuclein and other proteins are considered the cellular hallmark lesion. The cerebellar variant of MSA (MSA-C) denotes a distinctive motor subtype characterized by progressive adult onset sporadic gait ataxia, scanning dysarthria, limb ataxia and cerebellar oculomotor dysfunction. In addition, there is autonomic failure and variable degrees of parkinsonism. A range of other disorders may present with MSA-C like features and therefore the differential diagnosis of MSA-C is not always straightforward. Here we review key aspects of MSA-C including pathology, pathogenesis, diagnosis, clinical features and treatment, paying special attention to differential diagnosis in late onset sporadic cerebellar ataxias.

Identification of FXTAS presenting with SCA 12 like phenotype in India

BACKGROUND

Fragile X-associated Tremor/Ataxia syndrome (FXTAS) is a clinically heterogeneous disorder characterized predominantly by tremor, followed by late onset gait ataxia, autonomic dysfunction and/or cognitive impairment. We aimed to screen FMR1-CGG repeats in our cohort of progressive late-onset cerebellar ataxia/tremor cohort to characterize the occurrence of FXTAS in India.

METHODS

We have screened FMR1-CGG repeats in 109 patients and 173 healthy control subjects. Our cohort comprised: a)group of patients with predominant cerebellar ataxia and/or tremor. b.)suspected cases of MSA and c.)patients who presented SCA12-like neurological manifestations (late onset predominant tremor and/or ataxia). All the cases were ruled out for known triplet-repeat-expansion (TRE) SCA mutations.

RESULTS

We have found three FMR1-premutation carriers among the cases. Two of them (with CGG-96 and CGG-102) were under evaluation for their SCA12-like manifestations and another (CGG-78) had progressive gait ataxia. Overall the frequency of FXTAS in our cohort was found to be 3.3% among cases of late onset cerebellar-ataxia/tremor; however, incidences were higher among cases with SCA12-like syndrome (9%, 2/23).

CONCLUSION

Finding FXTAS in patients with SCA12-like manifestation suggests that TRE in the 5'UTR of the gene is the common cue connecting two disorders with common phenotype of tremor/ataxia. This knowledge might shed light upon their sharing of molecular neuropathology.

Tremor syndromes

PURPOSE OF REVIEW

The purpose of this review is to explain a practical clinical approach to the diagnosis and management of tremor.

RECENT FINDINGS

A number of rare but important causes of tremor have been delineated, which means that attention to detail in clinical assessment of patients with tremor is even more important.

SUMMARY

Tremors are best divided into those occurring mainly at rest, mainly on posture, and mainly during action. This basic division leads directly to differential diagnosis and effective treatment.

Towards an Understanding of Neuropsychiatric Manifestations in Fragile X Premutation Carriers

Fragile X-associated disorders (FXD) are a group of disorders caused by expansion of non-coding CGG repeat elements in the fragile X (FMR1) gene. One of these disorders, fragile X syndrome (FXS), is the most common heritable cause of intellectual disability, and is caused by large CGG repeat expansions (>200) resulting in silencing of the FMR1 gene. An increasingly recognized number of neuropsychiatric FXD have recently been identified that are caused by 'premutation' range expansions (55-200). These disorders are characterized by a spectrum of neuropsychiatric manifestations ranging from an increased risk of neurodevelopmental, mood and anxiety disorders to neurodegenerative phenotypes such as the fragile X-associated tremor ataxia syndrome (FXTAS). Here, we review advances in the clinical understanding of neuropsychiatric disorders in premutation carriers across the lifespan and offer guidance for the detection of such disorders by practicing psychiatrists and neurologists.

Multiple system atrophy of the cerebellar type: clinical state of the art

Multiple system atrophy (MSA) is a late-onset, sporadic neurodegenerative disorder clinically characterized by autonomic failure and either poorly levodopa-responsive parkinsonism or cerebellar ataxia. It is neuropathologically defined by widespread and abundant central nervous system α-synuclein-positive glial cytoplasmic inclusions and striatonigral and/or olivopontocerebellar neurodegeneration. There are two clinical subtypes of MSA distinguished by the predominant motor features: the parkinsonian variant (MSA-P) and the cerebellar variant (MSA-C). Despite recent progress in understanding the pathobiology of MSA, investigations into the symptomatology and natural history of the cerebellar variant of the disease have been limited. MSA-C presents a unique challenge to both clinicians and researchers alike. A key question is how to distinguish early in the disease course between MSA-C and other causes of adult-onset cerebellar ataxia. This is a particularly difficult question, because the clinical framework for conceptualizing and studying sporadic adult-onset ataxias continues to undergo flux. To date, several investigations have attempted to identify clinical features, imaging, and other biomarkers that may be predictive of MSA-C. This review presents a clinically oriented overview of our current understanding of MSA-C with a focus on evidence for distinguishing MSA-C from other sporadic, adult-onset ataxias.

EFNS/ENS Consensus on the diagnosis and management of chronic ataxias in adulthood

BACKGROUND AND OBJECTIVES

The ataxias are a challenging group of neurological diseases due the aetiological heterogeneity and the complexity of the genetic subtypes. This guideline focuses on the heredodegenerative ataxias. The aim is to provide a peer-reviewed evidence-based guideline for clinical neurologists and other specialist physicians responsible for the care of patients with ataxia.

METHODS

This guideline is based on systematic evaluations of the relevant literature and on three consensus meetings of the task force.

DIAGNOSIS

If acquired causes are ruled out, and if the disease course is rather slowly progressive, a (heredo)degenerative disease is likely. A positive family history gives much guidance. In the case of a dominant family history, first line genetic screening is recommended for spinocerebellar ataxia (SCA) 1, 2, 3, 6, 7 and 17 (level B), and in Asian patients also for dentatorubral-pallidoluysian atrophy (DRPLA). In the case of recessive disease, a stepwise diagnostic work-up is recommended, including both biochemical markers and targeted genetic testing, particularly aimed at Friedreich's ataxia, ataxia telangiectasia, ataxia due to vitamin E deficiency, polymerase gamma gene (POLG gene, various mutations), autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS) and ataxia with oculomotor apraxia (AOA) types 1 and 2. If family history is negative, we still advise to screen for the more common dominant and recessive ataxias. In addition, if onset is below 45 years we recommend the full work-up for recessive ataxias; if onset is above 45 years we recommend to screen for fragile X mental retardation 1 FMR1 premutations (good practice points). In sporadic cases with an onset after 30 years, a diagnosis of multiple system atrophy should be considered (good practice point). In particular the genetic work-up will change over the upcoming years due to the diagnostic utility of new techniques such as gene panel diagnostics based on next generation sequencing for routine work-up, or even whole exome and genome sequencing for selected cases.

TREATMENT

Some of the rare recessive ataxias are treatable, but for most of the heredodegenerative ataxias treatment is purely symptomatic. Idebenone is not effective in Friedreich's ataxia (level A). Riluzole (level B) and amantadine (level C) might provide symptomatic relief, irrespective of exact etiology. Also, varenicline for SCA3 patients (level B) can be considered. There is level Class II evidence to recommend physiotherapy, and Class III data to support occupational therapy.

Fragile X-associated tremor/ataxia syndrome (FXTAS) in grey zone carriers

The grey zone (GZ; 45-54 CGG repeats in the FMR1 gene) is considered a normal allele; however, several studies have found a high frequency of GZ in movement disordered populations. Here, we describe neurological features of fragile X-associated tremor/ataxia syndrome (FXTAS) in two carriers of GZ alleles, although FXTAS has been defined as occurring only in premutation carriers (55-200 CGG repeats). Both patients had family members who had premutation and were diagnosed with FXTAS. The presence of relatively high GZ alleles with elevated fragile X mental retardation 1 mRNA (FMR1-mRNA) combined with a family history of FXTAS that may represent a facilitating genetic background for FXTAS are the factors that led to the presence of FXTAS in these individuals with a GZ allele. Further research into clinical involvement of GZ alleles is recommended and the definition of FXTAS may require revision.

Fragile x-associated tremor ataxia syndrome: the expanding clinical picture, pathophysiology, epidemiology, and update on treatment

Fragile X-associated tremor/ataxia syndrome (FXTAS) is a progressive degenerative movement disorder characterized by kinetic tremor, cerebellar gait ataxia, parkinsonism, and cognitive decline. This disorder occurs in both males and females, frequently in families with children who have fragile X syndrome. The clinical features of this disorder, both classic and newly described, are summarized in this paper. In screening studies, fragile X mental retardation 1 (FMR1) gene premutation (55–200 CGG) expansions are most frequently seen in men with ataxia who have tested negative for spinocerebellar ataxias. Since the original description, the classic FXTAS phenotype has now been reported in females and in carriers of smaller (45–54 CGG) and larger (>200 CGG) expansions in FMR1. Premutation carriers may present with a Parkinson disease phenotype or hypotension, rather than with tremor and/or ataxia. Parkinsonism and gait ataxia may also be seen in individuals with gray zone (41–54 CGG) expansions. Studies regarding medication to treat the symptoms in FXTAS are few in number and suggest that medications targeted to specific symptoms, such as kinetic tremor or gait ataxia, may be most beneficial. Great progress has been made in regards to FXTAS research, likely given the readily available gene test and the screening of multiple family members, including parents and grandparents, of fragile X syndrome children. Expansion of genotypes and phenotypes in the disorder may suggest that a broader disease definition might be necessary in the future.

The neuropathology, pathophysiology and genetics of multiple system atrophy

Multiple system atrophy (MSA) is an unrelenting, sporadic, adult-onset, neurodegenerative disease of unknown aetiology. Its clinically progressive course is characterized by a variable combination of parkinsonism, cerebellar ataxia and/or autonomic dysfunction. Neuropathological examination often reveals gross abnormalities of the striatonigral and/or olivopontocerebellar systems, which upon microscopic examination are associated with severe neuronal loss, gliosis, myelin pallor and axonal degeneration. MSA is a member of a diverse group of neurodegenerative disorders termed α-synucleinopathies, due to the presence of abnormal α-synuclein positive cytoplasmic inclusions in oligodendrocytes, termed glial cytoplasmic inclusions. These are the hallmark neuropathological lesion of MSA and are thought to play a central role in the pathogenesis of the disease. In this review, neuropathological features of MSA are described in detail, along with recent advances in the pathophysiology and genetics of the disease. Our current knowledge of the expression and accumulation of α-synuclein, and efforts to model the disease in vitro and in vivo, are emphasized in this paper and have helped formulate a working hypothesis for the pathogenesis of MSA.

Fragile X-associated tremor/ataxia syndrome

Fragile X-associated tremor/ataxia syndrome (FXTAS) is an under-recognized disorder that is a significant cause of late-adult-onset ataxia. The etiology is expansion of a trinucleotide repeat to the premutation range (55-200 CGG repeats) in the fragile X mental retardation 1 (FMR1) gene. Expansion to >200 CGGs causes fragile X syndrome, the most common heritable cause of cognitive impairment and autism. Core features of FXTAS include progressive action tremor and gait ataxia; with frequent, more variable features of cognitive decline, especially executive dysfunction, parkinsonism, neuropathy, and autonomic dysfunction. MR imaging shows generalized atrophy and frequently abnormal signal in the middle cerebellar peduncles. Autopsy reveals intranuclear inclusions in neurons and astrocytes and dystrophic white matter. FXTAS is likely due to an RNA toxic gain-of-function of the expanded-repeat mRNA. The disorder typically affects male premutation carriers over age 50, and, less often, females. Females also are at increased risk for primary ovarian insufficiency, chronic muscle pain, and thyroid disease. Treatment targets specific symptoms, but progression of disability is relentless. Although the contribution of FXTAS to the morbidity and mortality of the aging population requires further study, the disorder is likely the most common single-gene form of tremor and ataxia in the older adult population.

Fragile X-associated tremor/ataxia syndrome: clinical phenotype, diagnosis, and treatment

Fragile X-associated tremor/ataxia syndrome (FXTAS) is a neurodegenerative disorder caused by a CGG repeat expansion in the premutation range (55-200) in the fragile X mental retardation 1 gene. Onset is typically in the early seventh decade, and men are principally affected. The major signs are cerebellar gait ataxia, intention tremor, frontal executive dysfunction, and global brain atrophy. Other frequent findings are parkinsonism (mild), peripheral neuropathy, psychiatric symptoms (depression, anxiety, and agitation), and autonomic dysfunction. The clinical presentation is heterogeneous, with individuals presenting with varied dominating signs, such as tremor, dementia, or neuropathy. Magnetic resonance imaging shows atrophy and patchy white matter lesions in the cerebral hemispheres and middle cerebellar peduncles. The latter has been designated the middle cerebellar peduncle sign, which occurs in about 60% of affected men, and is relatively specific for FXTAS. Affected females generally have less severe disease, less cognitive decline, and some symptoms different from that of men, for example, muscle pain. Management of FXTAS is complex and includes assessment of the patient's neurological and medical deficits, treatment of symptoms, and provision of relevant referrals, especially genetic counseling. Treatment is empirical, based on anecdotal experience and on knowledge of what works for symptoms of other disorders that also exist in FXTAS. Presently, the disorder is underrecognized because the first published report was only in 2001 and because the presentation is variable and mainly consists of a combination of signs common in the elderly. However, accurate diagnosis is critical for the patient and for the family because they need education regarding their genetic and health risks.

CGG repeat in the FMR1 gene: size matters

The FMR1 gene contains a CGG repeat present in the 5'-untranslated region which can be unstable upon transmission to the next generation. The repeat is up to 55 CGGs long in the normal population. In patients with fragile X syndrome (FXS), a repeat length exceeding 200 CGGs (full mutation: FM) generally leads to methylation of the repeat and the promoter region, which is accompanied by silencing of the FMR1 gene. The absence of FMR1 protein, FMRP, seen in FM is the cause of the mental retardation in patients with FXS. The premutation (PM) is defined as 55-200 CGGs. Female PM carriers are at risk of developing primary ovarian insufficiency. Elderly PM carriers might develop a progressive neurodegenerative disorder called fragile X-associated tremor/ataxia syndrome (FXTAS). Although arising from the mutations in the same gene, distinct mechanisms lead to FXS (absence of FMRP), FXTAS (toxic RNA gain-of-function) and FXPOI. The pathogenic mechanisms thought to underlie these disorders are discussed. This review gives insight on the implications of all possible repeat length categories seen in fragile X families.

FXTAS is rare among Portuguese patients with movement disorders: FMR1 premutations may be associated with a wider spectrum of phenotypes

The fragile X-associated tremor/ataxia syndrome (FXTAS) is a late-onset neurodegenerative disorder caused by expansions of 55-200 CGG repeats in the 5'UTR of the FMR1 gene. These FMR1 premutation expansions have relatively high frequency in the general population. To estimate the frequency of FMR1 premutations among Portuguese males with non-familial, late-onset movement disorders of unknown etiology, we assessed CGG repeat size in males with disease onset after the age of 50 and negative or unknown family history for late-onset movement disorders, who were sent for SCA, HD, or PD genetic testing at a reference laboratory. The selected patients had a primary clinical diagnosis based on one of the following cardinal features of FXTAS: ataxia, tremor, or cognitive decline. A total of 86 subjects were genotyped for the CGG repeat in the FMR1 gene. We detected one patient with an expansion in the premutation range. The frequency of FMR1 premutations was 1.9% (1/54) in our group of patients with ataxia as the primary clinical feature, and 1.2% (1/86) in the larger movement disorders group. In the family of the FXTAS case, premutation-transmitting females presented a history of psychiatric symptoms, suggesting that, given the wide phenotypical expression of the premutation in females, neuropsychiatric surveillance is necessary. In conclusion, genetic testing for FXTAS should be made available to patients with adult-onset movement disorders to enable adequate genetic counseling to family members.

Genetic players in multiple system atrophy: unfolding the nature of the beast

Multiple system atrophy (MSA) is a fatal oligodendrogliopathy characterized by prominent α-synuclein inclusions resulting in a neuronal multisystem degeneration. Until recently MSA was widely conceived as a nongenetic disorder. However, during the last years a few postmortem verified Mendelian pedigrees have been reported consistent with monogenic disease in rare cases of MSA. Further, within the last 2 decades several genes have been associated with an increased risk of MSA, first and foremost the SNCA gene coding for α-synuclein. Moreover, genes involved in oxidative stress, mitochondrial dysfunction, inflammatory processes, as well as parkinsonism- and ataxia-related genes have been implicated as susceptibility factors. In this review, we discuss the emerging evidence in favor of genetic players in MSA.

Genetic players in multiple system atrophy: unfolding the nature of the beast

Multiple system atrophy (MSA) is a fatal oligodendrogliopathy characterized by prominent α-synuclein inclusions resulting in a neuronal multisystem degeneration. Until recently MSA was widely conceived as a nongenetic disorder. However, during the last years a few postmortem verified Mendelian pedigrees have been reported consistent with monogenic disease in rare cases of MSA. Further, within the last 2 decades several genes have been associated with an increased risk of MSA, first and foremost the SNCA gene coding for α-synuclein. Moreover, genes involved in oxidative stress, mitochondrial dysfunction, inflammatory processes, as well as parkinsonism- and ataxia-related genes have been implicated as susceptibility factors. In this review, we discuss the emerging evidence in favor of genetic players in MSA.

Sleep disorders in cerebellar ataxias

Cerebellar ataxias comprise a wide range of etiologies leading to central nervous system-related motor and non-motor symptoms. Recently, a large body of evidence has demonstrated a high frequency of non-motor manifestations in cerebellar ataxias, specially in autosomal dominant spinocerebellar ataxias (SCA). Among these non-motor dysfunctions, sleep disorders have been recognized, although still under or even misdiagnosed. In this review, we highlight the main sleep disorders related to cerebellar ataxias focusing on REM sleep behavior disorder (RBD), restless legs syndrome (RLS), periodic limb movement in sleep (PLMS), excessive daytime sleepiness (EDS), insomnia and sleep apnea.

New clinical findings in the fragile X-associated tremor ataxia syndrome (FXTAS)

The objective of this paper was to assess the phenotypic variance in patients with the Fragile X-associated Tremor Ataxia Syndrome (FXTAS) and to further elucidate genotype-phenotype correlations in the illness. A second goal was to generate hypotheses regarding symptom progression based on careful histories in our sample that can now be tested in ongoing longitudinal studies. The variability of clinical signs and symptom progression in FXTAS complicates our understanding of its phenotype and presents a series of problems in clinical trial design. Similarly, pre-motor and non-motor symptoms have not been adequately explored to answer outstanding questions regarding genotype-phenotype associations in FXTAS. This was a cross-sectional study of FMR1 premutation carriers from known fragile X syndrome pedigrees. We report on the first 50 subjects who have completed a full neurologic evaluation and a brain MRI. Subjects were selected on the basis of motor symptoms or abnormal results (>1 SD) on a quantitative instrument designed to detect mild tremor and ataxia (CATSYS 1994). A neuropsychological battery included the WAIS-III, COWA, and WCST. Statistical analysis used ANOVA and Fisher's exact test with p < 0.05. All FMR1 premutation carriers were men of mean age 65 ± 7 years. According to the diagnostic criteria of Jacquemont et al. (Am J Hum Genet 72(4):869-878, 2003), 21 subjects met criteria for definite FXTAS, 10 for probable, 9 for possible, and 10 were indeterminate. Duration of motor symptoms was significantly longer in the definitive group (8.6 ± 6) compared to the other groups (p < 0.01). The presentations in 40 subjects, excluding the indeterminate group, included: tremor 24, ataxia 5, memory symptoms 3, parkinsonism 2, and torticollis 1. The data suggest at least two dominant phenotypic presentations: (a) a tremor-dominant subtype in which the onset of ataxia is delayed; (b) a second in which ataxia is the dominant presentation from the outset. In both subtypes, once ataxia emerges it tends to track frontal cognitive changes (p < 0.01). The data support the view that FXTAS is a late-life neurodegenerative disorder with involvement of motor, non-motor, and cognitive systems. The results suggest at least two presentations with tremor- and ataxia-predominant phenotypes. In both, global cognitive decline appears to track ataxia. Prospective longitudinal studies are needed to validate this proposed evolution of FXTAS and its relevance to future clinical trials design.

[Fragile X-associated tremor/ataxia syndrome]

Fragile X-associated tremor/ataxia syndrome (FXTAS) is a recently characterized adult onset neurodegenerative disorder affecting both male and female (male>female) carriers of premutation CGG repeat expansions of the FMR1 gene. Onset typically occurs after the age of 50 years with a lifetime risk of FXTAS in males of about 1 in 3,000-6,000. Core features include progressive gait ataxia and cerebellar tremor with associated features of cognitive deficits, peripheral neuropathy and dysautonomia. The diagnosis of FXTAS is established based on clinical presentation, cerebral imaging and genetic testing. Due to the still low level of awareness of FXTAS and its variable clinical picture FXTAS is substantially underdiagnosed. However, confirming the diagnosis is essential for genetic counseling of the patients as the offspring are at risk for fragile X syndrome, premature ovarian insufficiency (POI) or FXTAS. Furthermore, many features of FXTAS can be treated symptomatically.