Adult onset sporadic ataxias: a diagnostic challenge

Ataxias in Brazil: 17 years of experience in an ataxia center

BACKGROUND

 Cerebellar ataxias comprise sporadic and genetic etiologies. Ataxia may also be a presenting feature in hereditary spastic paraplegias (HSPs).

OBJECTIVE

 To report a descriptive analysis of the frequency of different forms of cerebellar ataxia evaluated over 17 years in the Ataxia Unit of Universidade Federal de São Paulo, Brazil.

METHODS

 Charts of patients who were being followed from January 2007 to December 2023 were reviewed. We used descriptive statistics to present our results as frequencies and percentages of the overall analysis. Diagnosed patients were classified according to the following 9 groups: sporadic ataxia, spinocerebellar ataxias (SCAs), other autosomal dominant cerebellar ataxias, autosomal recessive cerebellar ataxias (ARCAs), mitochondrial ataxias, congenital ataxias, X-linked ataxias, HSPs, and others.

RESULTS

 There were 1,332 patients with ataxias or spastic paraplegias. Overall, 744 (55.85%) of all cases were successfully diagnosed: 101 sporadic ataxia, 326 SCAs, 20 of other autosomal dominant cerebellar ataxias, 186 ARCAs, 6 X-linked ataxias, 2 mitochondrial ataxias, 4 congenital ataxias, and 51 HSPs.

CONCLUSION

 This study describes the frequency of cerebellar ataxias in a large group of patients followed for the past 17 years, of whom 55% obtained a definitive clinical or molecular diagnosis. Future demographic surveys in Brazil or Latin American remain necessary.

ACR Appropriateness Criteria® Dizziness and Ataxia: 2023 Update

Diagnostic evaluation of a patient with dizziness or vertigo is complicated by a lack of standardized nomenclature, significant overlap in symptom descriptions, and the subjective nature of the patient's symptoms. Although dizziness is an imprecise term often used by patients to describe a feeling of being off-balance, in many cases dizziness can be subcategorized based on symptomatology as vertigo (false sense of motion or spinning), disequilibrium (imbalance with gait instability), presyncope (nearly fainting or blacking out), or lightheadedness (nonspecific). As such, current diagnostic paradigms focus on timing, triggers, and associated symptoms rather than subjective descriptions of dizziness type. Regardless, these factors complicate the selection of appropriate diagnostic imaging in patients presenting with dizziness or vertigo. This document serves to aid providers in this selection by using a framework of definable clinical variants. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where peer reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.

Functional ataxia in a specialized ataxia center

BACKGROUND

Functional gait is a disorder of ambulation and balance internally inconsistent and incongruent with the phenotypic spectrum of neurological gait disorders.

OBJECTIVES

This paper aims to clinically characterize patients with functional ataxia.

METHODS

Patients with functional ataxia were analyzed out of 1350 patients in Ataxia Unit of the Federal University of São Paulo circa 2008 to 2022.

RESULTS

Thirteen patients (1 %) presented with functional ataxia; all female, with a median age of 34.8 years. Six (46.2 %) had psychiatric comorbidities and 7 (53.8 %) endorsed a trigger. Diagnostic features included variable base and stride (100 %), "huffing and puffing" (30.7 %), knee-buckling (30.7 %), uneconomic posturing (38.5 %), tightrope walking (23 %), and trembling gait (15.4 %). Remarkably, no falls were reported in any case. 53.8 % recovered fully or partially, despite no treatment.

CONCLUSIONS

Variability of base and stride are universal features of functional ataxia, yet falls are inconspicuous. Functional Ataxia is rare even in a specialized ataxia center.

Anti-Tr/DNER antibody-associated cerebellar ataxia: three rare cases report and literature review

BACKGROUND

To report three cases of autoimmune cerebellar ataxia related to anti-delta/notch-like epidermal growth factor-related receptor (Tr/DNER) antibodies.

CASE PRESENTATION

Patients with unknown cerebellar ataxia were screened with autoimmune cerebellar ataxia (ACA)-related antibody panel. The anti-Tr antibody was positive in three female patients in whom the onset ages were 43 years, 35 years and 43 years old. The antibody titres of serum and cerebrospinal fluid were all 1:32. Cerebral ataxia was the most prominent presentation. Mild cerebellar atrophy was found in one of the patients. Immunotherapy was effective in all three patients.

CONCLUSION

The Tr antibody is associated with autoimmune ataxia, and it has been suggested that the anti-Tr antibody should be tested in patients with cerebellar ataxia who are negative for routine ACA antibodies. Early immunotherapy may improve patient prognoses.

A Proposed Clinical Classification and a Diagnostic Approach for Congenital Ataxias

Purpose of Review

This review proposes a clinical classification for congenital ataxias based on clinical features, neuroimaging, and course of the disease.

Recent Findings

Congenital ataxias are an unusual group of neurologic disorders, with heterogeneous clinical and genetic presentation. Typical clinical features of congenital ataxias include variable degrees of motor developmental delay, very early onset cerebellar ataxia, cognitive impairment, and hypotonia, frequently mistakenly diagnosed as cerebral palsy. Congenital ataxias are usually nonprogressive. Neuroimaging plays an important role in the characterization of congenital ataxias. Despite the development of genetics with exome sequencing, several congenital ataxias remain undetermined, and medical literature on this topic is scarce.

Summary

A didactic classification based on the clinical and neuroimaging features for congenital ataxias include the following 4 main groups: cerebellar malformation, syndromic congenital ataxias, congenital cerebellar hypoplasia, and pontocerebellar hypoplasia. A diagnostic approach for congenital ataxias is proposed, and its differential diagnosis is also discussed.

Diagnostic Yield of Whole Exome Sequencing for Adults with Ataxia: a Brazilian Perspective

Previous studies using whole exome sequencing (WES) have shown that a significant proportion of adult patients with undiagnosed ataxia in European and North American cohorts have a known genetic cause. Little is known about the diagnostic yield of WES in non-Caucasian ataxic populations. Herein, we used WES to investigate a Brazilian cohort of 76 adult patients with idiopathic ataxia previously screened for trinucleotide expansions in known ataxia genes. We collected clinical and radiological data from each patient. WES was performed following standard procedures. Only variants labeled as pathogenic or likely pathogenic according to American college of medical genetics and genomics (ACMG) criteria were retrieved. We determined the diagnostic yield of WES for the whole cohort and also for subgroups defined according to presence or not of pyramidal signs, peripheral neuropathy, and cerebellar atrophy. There were 41 women and 35 men. Mean age at testing was 48 years. Pyramidal signs, peripheral neuropathy, tremor, and cerebellar atrophy were found in 38.1%, 13.1%, 10.5%, and 68.3% of all subjects, respectively. Diagnostic yield of WES was 35.5%. Thirty-six distinct mutations were found in 20 different genes, determining the diagnosis of 18 autosomal recessive and 9 autosomal dominant ataxias. SACS and SPG7 were the most frequently found underlying genes. WES performed better in the subgroup with vs the subgroup without spasticity (p = 0.005). WES was diagnostic in 35.5% of cases of the Brazilian cohort of ataxia cases. These results have implications for diagnosis, genetic counseling and eventually treatment.

Should we investigate mitochondrial disorders in progressive adult-onset undetermined ataxias?

Background

Despite the broad development of next-generation sequencing approaches recently, such as whole-exome sequencing, diagnostic workup of adult-onset progressive cerebellar ataxias without remarkable family history and with negative genetic panel testing for SCAs remains a complex and expensive clinical challenge.

Case presentation

In this article, we report a Brazilian man with adult-onset slowly progressive pure cerebellar ataxia, which developed neuropathy and hearing loss after fifteen years of ataxia onset, in which a primary mitochondrial DNA defect (MERRF syndrome - myoclonus epilepsy with ragged-red fibers) was confirmed through muscle biopsy evaluation and whole-exome sequencing.

Conclusions

Mitochondrial disorders are a clinically and genetically complex and heterogenous group of metabolic diseases, resulting from pathogenic variants in the mitochondrial DNA or nuclear DNA. In our case, a correlation with histopathological changes identified on muscle biopsy helped to clarify the definitive diagnosis. Moreover, in neurodegenerative and neurogenetic disorders, some symptoms may be evinced later during disease course. We suggest that late-onset and adult pure undetermined ataxias should be considered and investigated for mitochondrial disorders, particularly MERRF syndrome and other primary mitochondrial DNA defects, together with other more commonly known nuclear genes.

Deafness and Vestibulopathy in Cerebellar Diseases: a Practical Approach

Cerebellar ataxias are a clinically heterogeneous group of neurological disorders. Besides the cerebellum, several forms of hereditary ataxias or non-genetic ataxias also affect other areas of the brain. Some forms of cerebellar ataxias may have cochlear and vestibular involvement and may present with deafness and symptoms or signs of vestibulopathy (dizziness, nystagmus and diplopia). Recognizing otoneurological symptoms in patients with cerebellar ataxias is mandatory, since these signs may guide a specific diagnosis, and clinicians may provide a suitable therapeutic approach. In this review, we describe and discuss the most common forms of cerebellar ataxias associated with deafness and vestibulopathy.

Movement Disorders in Genetic Pediatric Ataxias

Background

Genetic pediatric ataxias are heterogeneous rare disorders, mainly inherited as autosomal-recessive traits. Most forms are progressive and lack effective treatment, with relevant socioeconomical impact. Albeit ataxia represents the main clinical feature, the phenotype can be more complex, with additional neurological and nonneurological signs being described in several forms.

Methods and Results

In this review, we provide an overview of the occurrence and spectrum of movement disorders in the most relevant forms of childhood-onset genetic ataxias. All types of hypokinetic and hyperkinetic movement disorders of variable severity have been reported. Movement disorders occasionally represent the symptom of onset, predating ataxia even of a few years and therefore challenging an early diagnosis. Their pathogenesis still remains poorly defined, as it is not yet clear whether movement disorders may directly relate to the cerebellar pathology or result from an extracerebellar dysfunction, including the basal ganglia.

Conclusion

Recognition of the complete movement disorder phenotype in genetic pediatric ataxias has important implications for diagnosis, management, and genetic counseling.

The cerebellar form of acquired hepatocerebral degeneration: The hepatic ataxia

This article reports a patient with acquired hepatocerebral degeneration that presented with progressive cerebellar ataxia, cerebellar atrophy, and middle cerebellar peduncle lesions. He had a marked improvement after liver transplantation. We reinforce that hepatic failure should be investigated in patients with pure cerebellar syndrome, resembling neurodegenerative diseases.

Acute cerebellar ataxia: differential diagnosis and clinical approach

Cerebellar ataxia is a common finding in neurological practice and has a wide variety of causes, ranging from the chronic and slowly-progressive cerebellar degenerations to the acute cerebellar lesions due to infarction, edema and hemorrhage, configuring a true neurological emergency. Acute cerebellar ataxia is a syndrome that occurs in less than 72 hours, in previously healthy subjects. Acute ataxia usually results in hospitalization and extensive laboratory investigation. Clinicians are often faced with decisions on the extent and timing of the initial screening tests, particularly to detect treatable causes. The main group of diseases that may cause acute ataxias discussed in this article are: stroke, infectious, toxic, immune-mediated, paraneoplastic, vitamin deficiency, structural lesions and metabolic diseases. This review focuses on the etiologic and diagnostic considerations for acute ataxia.

Clinics in diagnostic imaging (191). Multiple system atrophy-cerebellar type (MSA-C)

A 49-year-old Chinese man was evaluated for progressive uncoordinated movements, dysphagia and urinary symptoms. Magnetic resonance imaging demonstrated a cruciform pattern of T2-weighted hyperintensity within the pons and selective atrophy of the cerebellar hemispheres and pons. The clinical history and radiological findings were consistent with a diagnosis of multiple system atrophy-cerebellar type. This article discussed the background, proposed mechanisms, diagnosis, radiological characteristics, prognosis and management of multiple system atrophy-cerebellar type.

Cerebellar degeneration and progressive ataxia associated with HIV-virus infection

INTRODUCTION

The spectrum of neurologic disorders associated with HIV infection is very broad, resulting from direct virus invasion, opportunistic infections, malignancies and toxic effects of drugs.

METHODS

Among a large cohort of ataxia patients (N = 1050) evaluated between 2008 and 2017, we detected four patients with HIV-infection who developed a pure progressive cerebellar ataxia syndrome combined with cerebellar atrophy.

RESULTS

Adverse drug effects, opportunistic infections and malignancies as well as immune-reconstitution syndrome were ruled out based on history and laboratory data. The exact pathophysiological mechanisms of ataxia in HIV patients is not very clear, but seems to be immune-mediated or a direct neurotoxic virus effect leading to apoptosis of Purkinje and granular cells.

CONCLUSION

HIV infection should be investigated in adult patients with undetermined sporadic progressive pure ataxia with cerebellar atrophy.

Ataxia

PURPOSE OF REVIEW

This article introduces the background and common etiologies of ataxia and provides a general approach to assessing and managing the patient with ataxia.

RECENT FINDINGS

Ataxia is a manifestation of a variety of disease processes, and an underlying etiology needs to be investigated. Pure ataxia is rare in acquired ataxia disorders, and associated symptoms and signs almost always exist to suggest an underlying cause. While the spectrum of hereditary degenerative ataxias is expanding, special attention should be addressed to those treatable and reversible etiologies, especially potentially life-threatening causes. This article summarizes the diseases that can present with ataxia, with special attention given to diagnostically useful features. While emerging genetic tests are becoming increasingly available for hereditary ataxia, they cannot replace conventional diagnostic procedures in most patients with ataxia. Special consideration should be focused on clinical features when selecting a cost-effective diagnostic test.

SUMMARY

Clinicians who evaluate patients with ataxia should be familiar with the disease spectrum that can present with ataxia. Following a detailed history and neurologic examination, proper diagnostic tests can be designed to confirm the clinical working diagnosis.

Non-progressive cerebellar ataxia and previous undetermined acute cerebellar injury: a mysterious clinical condition

Cerebellar ataxias represent a wide group of neurological diseases secondary to dysfunctions of cerebellum or its associated pathways, rarely coursing with acute-onset acquired etiologies and chronic non-progressive presentation. We evaluated patients with acquired non-progressive cerebellar ataxia that presented previous acute or subacute onset. Clinical and neuroimaging characterization of adult patients with acquired non-progressive ataxia were performed. Five patients were identified with the phenotype of acquired non-progressive ataxia. Most patients presented with a juvenile to adult-onset acute to subacute appendicular and truncal cerebellar ataxia with mild to moderate cerebellar or olivopontocerebellar atrophy. Establishing the etiology of the acute triggering events of such ataxias is complex. Non-progressive ataxia in adults must be distinguished from hereditary ataxias.