Cerebellar cognitive disorder parallels cerebellar motor symptoms in Friedreich ataxia

Cognitive Complaints and Their Impact on Daily Life in Patients with Degenerative Cerebellar Disorders

Cognitive and affective sequelae of cerebellar disease are receiving increased attention, but their actual rate of occurrence remains unclear. Complaints may have a significant impact on patients, affecting social behavior and psychological well-being. This study aims to explore the extent of subjective cognitive and affective symptoms in patients with degenerative ataxias in the Netherlands. An explorative study was set up in a heterogeneous group of degenerative ataxia patients. Self-reported cognition was evaluated in terms of executive functioning and affect (Dysexecutive Questionnaire/DEX), and memory/attention (Cognitive Failures Questionnaire/CFQ). The Daily Living Questionnaire (DLQ) was administered to quantify the impact on daily life. Furthermore, informants completed questionnaires to obtain insight into patients' self-awareness and social cognition (Observable Social Cognition Rating Scale/OSCARS). This study shows that subjective complaints in the domains of (1) executive functioning and/or (2) memory and attention were reported by 29% of all patients (n = 24/84). In addition, more difficulties in daily life in terms of language/comprehension and community/participation were reported, and this was more common for patients with cognitive complaints than those without. Discrepancies between patients and informants about executive functioning were present in both directions. Deficits in social cognition were not identified at the group level, but more social-cognitive problems were observed in patients with more executive problems rated by informants. Taken together, our findings indicate that cognitive complaints are common in patients with degenerative cerebellar disorders and have an impact on daily life functioning. These results may help to increase awareness of cognitive symptoms and their impact in patients with cerebellar ataxia, their significant others, and professional caregivers.

The Role of Verbal Fluency in the Cerebellar Cognitive Affective Syndrome Scale in Friedreich Ataxia

Cerebellar pathology engenders the disturbance of movement that characterizes Friedreich ataxia (FRDA), yet the impact of cerebellar pathology on cognition in FRDA remains unclear. Numerous studies have unequivocally demonstrated the role of the cerebellar pathology in disturbed cognitive, language and affective regulation, referred to as Cerebellar Cognitive Affective Syndrome (CCAS), and quantified by the CCAS-Scale (CCAS-S). The presence of dysarthria in many individuals with ataxia, particularly FRDA, may confound results on some items of the CCAS-S resulting in false-positive scores. This study explored the relationship between performance on the CCAS-S and clinical metrics of disease severity in 57 adults with FRDA. In addition, this study explored the relationship between measures of intelligibility and naturalness of speech and scores on the CCAS-S in a subgroup of 39 individuals with FRDA. We demonstrated a significant relationship between clinical metrics and performance on the CCAS-S. In addition, we confirmed the items that returned the greatest rate of failure were based on Verbal Fluency Tasks, revealing a significant relationship between these items and measures of speech. Measures of speech explained over half of the variance in the CCAS-S score suggesting the role of dysarthria in the performance on the CCAS-S is not clear. Further work is required prior to adopting the CCAS-S as a cognitive screening tool for individuals with FRDA.

The Cerebellar Cognitive Affective/Schmahmann Syndrome Scale in Spinocerebellar Ataxias

The Cerebellar Cognitive Affective/Schmahmann Syndrome (CCAS) manifests as impaired executive control, linguistic processing, visual spatial function, and affect regulation. The CCAS has been described in the spinocerebellar ataxias (SCAs), but its prevalence is unknown. We analyzed results of the CCAS/Schmahmann Scale (CCAS-S), developed to detect and quantify CCAS, in two natural history studies of 309 individuals Symptomatic for SCA1, SCA2, SCA3, SCA6, SCA7, or SCA8, 26 individuals Pre-symptomatic for SCA1 or SCA3, and 37 Controls. We compared total raw scores, domain scores, and total fail scores between Symptomatic, Pre-symptomatic, and Control cohorts, and between SCA types. We calculated scale sensitivity and selectivity based on CCAS category designation among Symptomatic individuals and Controls, and correlated CCAS-S performance against age and education, and in Symptomatic patients, against genetic repeat length, onset age, disease duration, motor ataxia, depression, and fatigue. Definite CCAS was identified in 46% of the Symptomatic group. False positive rate among Controls was 5.4%. Symptomatic individuals had poorer global CCAS-S performance than Controls, accounting for age and education. The domains of semantic fluency, phonemic fluency, and category switching that tap executive function and linguistic processing consistently separated Symptomatic individuals from Controls. CCAS-S scores correlated most closely with motor ataxia. Controls were similar to Pre-symptomatic individuals whose nearness to symptom onset was unknown. The use of the CCAS-S identifies a high CCAS prevalence in a large cohort of SCA patients, underscoring the utility of the scale and the notion that the CCAS is the third cornerstone of clinical ataxiology.

Cognitive-Affective Functions of the Cerebellum

The cerebellum, traditionally associated with motor coordination and balance, also plays a crucial role in various aspects of higher-order function and dysfunction. Emerging research has shed light on the cerebellum's broader contributions to cognitive, emotional, and reward processes. The cerebellum's influence on autonomic function further highlights its significance in regulating motivational and emotional states. Perturbations in cerebellar development and function have been implicated in various neurodevelopmental disorders, including autism spectrum disorder and attention deficit hyperactivity disorder. An increasing appreciation for neuropsychiatric symptoms that arise from cerebellar dysfunction underscores the importance of elucidating the circuit mechanisms that underlie complex interactions between the cerebellum and other brain regions for a comprehensive understanding of complex behavior. By briefly discussing new advances in mapping cerebellar function in affective, cognitive, autonomic, and social processing and reviewing the role of the cerebellum in neuropathology beyond the motor domain, this Mini-Symposium review aims to provide a broad perspective of cerebellar intersections with the limbic brain in health and disease.

Cognitive impairment in essential tremor assessed by the cerebellar cognitive affective syndrome scale

Background

Essential tremor (ET) is a movement disorder characterized by cerebellar neurodegenerative changes. ET is also associated with non-motor symptoms including cognitive impairment. The neuropsychologic profile of a patient with ET could relate to cerebellar cognitive affective syndrome (CCAS).

Objective

This study aimed to assess the prevalence of cognitive impairment in patients with ET and identify whether the cognitive impairment in ET corresponds to a CCAS.

Methods

Cognitive functions were evaluated with the CCAS-Scale (CCAS-S) in 20 patients with ET and 20 controls matched for age, sex, and level of education. The results of the CCAS-S were compared between patients and controls. The underlying determinant of CCAS inpatients with ET was identified through the correlation between the results of the CCAS-S and age at onset of symptoms, disease duration, and the Essential Tremor Rating Assessment Scale (TETRAS).

Results

On a group level, ET patients performed significantly worse than matched controls. In total, 13 individuals with ET had a definite CCAS (CCAS-S failed items ≥ 3). ASO and TETRAS scores significantly correlated with CCAS-S performances in ET patients.

Conclusion

CCAS is highly prevalent in patients with ET which supports the cerebellar pathophysiology of associated cognitive impairment and supports a more systematic use of the CCAS-S to cognitively assessed patients with ET.

Translation, Cross-Cultural Adaptation, and Validation to Brazilian Portuguese of the Cerebellar Cognitive Affective/Schmahmann Syndrome Scale

Cerebellar cognitive affective syndrome (CCAS) is characterized by deficits in executive functions, language processing, spatial orientation, and affect regulation in patients with cerebellar disease. The symptoms can occur isolated or along with motor and coordination symptoms. The aim of our study was to translate and culturally adapt the CCAS scale to Brazilian Portuguese and validate the scale in our population. We performed a cross-sectional study with patients with primary and secondary ataxia. The study included 111 individuals, aged between 20 and 80 years, of both genders, 20 without cognitive and/or affective complaints who participated in the pre-test phase, 40 with cerebellar disease (hereditary/neurodegenerative ataxia or acquired/secondary cerebellar ataxia), and 51 healthy controls with no evidence of cognitive impairment and no affective symptoms matched for sex, age, and educational level. The scale was translated, culturally adapted, and validated. Statistical analysis of the data was performed, with association tests, mean comparison, and ROC curve analysis. Based on the analysis of the ROC curve, optimal cutoff values ​were found for each subitem of the scale. The translated and adapted scale has good internal consistency, is reproducible, has good reliability, and has the potential to be a reliable tool for screening cognitive symptoms in patients with cerebellar disease.

Coordination and Cognition in Pure Nutritional Wernicke’s Encephalopathy with Cerebellar Degeneration after COVID-19 Infection: A Unique Case Report

Background: Alcoholic cerebellar degeneration is a restricted form of cerebellar degeneration, clinically leading to an ataxia of stance and gait and occurring in the context of alcohol misuse in combination with malnutrition and thiamine depletion. However, a similar degeneration may also develop after non-alcoholic malnutrition, but evidence for a lasting ataxia of stance and gait and lasting abnormalities in the cerebellum is lacking in the few patients described with purely nutritional cerebellar degeneration (NCD). Methods: We present a case of a 46-year-old woman who developed NCD and Wernicke’s encephalopathy (WE) due to COVID-19 and protracted vomiting, resulting in thiamine depletion. We present her clinical course over the first 6 months after the diagnosis of NCD and WE, with thorough neuropsychological and neurological examinations, standardized clinical observations, laboratory investigations, and repeated MRIs. Results: We found a persistent ataxia of stance and gait and evidence for an irreversible restricted cerebellar degeneration. However, the initial cognitive impairments resolved. Conclusions: Our study shows that NCD without involvement of alcohol neurotoxicity and with a characteristic ataxia of stance and gait exists and may be irreversible. We did not find any evidence for lasting cognitive abnormalities or a cerebellar cognitive-affective syndrome (CCAS) in this patient.

Determinant of the cerebellar cognitive affective syndrome in Friedreich's ataxia

BACKGROUND

Individuals with Friedreich's ataxia (FRDA) display significantly lower performances in many cognitive domains with a pattern of impairment that falls within the cerebellar cognitive affective syndrome (CCAS).

OBJECTIVE

To assess in a large cohort of individuals with FRDA, the main determinant of the CCAS using multiple variable regression models.

METHODS

This is a monocentric observational study that included 39 individuals with FRDA. Ataxic motor symptoms were evaluated with the SARA and cognitive functions with the CCAS-Scale (CCAS-S). Age, SARA, GAA1, Age of symptoms onset (ASO), Age and disease duration (DD) were chosen as covariates in a linear regression model to predict CCAS-S failed items and covariates in a logistic regression model to predict definite CCAS.

RESULTS

Patients mean age, SARA score, ASO, DD and GAA1 were respectively of 29 ± 14, 22 ± 10, 14 ± 11, 15 ± 9 and 712 ± 238 (4 point-mutations). Mean CCAS-S raw score was of 86 ± 16, mean number of failed items was 2.9 ± 1.6. Twenty-three individuals had definite CCAS. The multiple linear regression model with age, SARA, ASO, DD & GAA1 as covariates was statistically significant to predict CCAS-S failed items. The SARA was the only significant coefficient in regression models for predicting CCAS-S failed items number and the definite CCAS occurrence.

CONCLUSIONS

CCAS is highly prevalent in adult individuals with FRDA. CCAS is predicted by ataxic motor symptoms severity. This finding supports common core cerebellar pathophysiology in both cognitive and motor symptoms in FRDA and warrants screening for CCAS, especially in patients with SARA > 20.

Crossed Cerebellar Diaschisis Worsens the Clinical Presentation in Acute Large Vessel Occlusion

INTRODUCTION

Initial NIHSS in anterior large vessel occlusion (LVO) correlates partially with the hypoperfusion volume. We aimed at assessing the contribution of crossed cerebellar diaschisis (CCD) from the hypoperfused territory on LVO initial clinical deficit.

METHODS

CCD was retrospectively identified by brain CT perfusion imaging (CTP) in patients with anterior LVO treated by mechanical thrombectomy from January 2017 to July 2021. CCD was defined by CTP parameter alteration in the contralateral cerebellar hemisphere to the LVO. NIHSS, clinical/perfusion variables, and CCD were included in regression models to assess their interrelationships.

RESULTS

206 patients were included. CCD was present in 90 patients (69%). NIHSS scores were higher on admission and at stroke discharge among patients with CCD (17.90 ± 6.1 vs. 11.4 ± 8.4, p < 0.001; 9.6 ± 7.7 vs. 6.6 ± 7.9, p = 0.049; respectively). Patients with a CCD had higher stroke volumes (118.2 ± 60.3 vs. 69.3 ± 59.7, p < 0.001) and lower rate of known atrial fibrillation (22% vs. 41%, p = 0.021). On multivariable logistic regression, CCD independently worsened the initial NIHSS (OR 4.85 [2.37-7.33]; p < 0.001).

CONCLUSION

CCD is found in 69% of LVO on admission CTP, correlates with stroke volumes, and independently worsens initial NIHSS.

Cerebellar cognitive affective syndrome after acute cerebellar stroke

Introduction

The cerebellum modulates both motor and cognitive behaviors, and a cerebellar cognitive affective syndrome (CCAS) was described after a cerebellar stroke in 1998. Yet, a CCAS is seldom sought for, due to a lack of practical screening scales. Therefore, we aimed at assessing both the prevalence of CCAS after cerebellar acute vascular lesion and the yield of the CCAS-Scale (CCAS-S) in an acute stroke setting.

Materials and methods

All patients admitted between January 2020 and January 2022 with acute onset of a cerebellar ischemic or haemorrhagic first stroke at the CUB-Hôpital Erasme and who could be evaluated by the CCAS-S within a week of symptom onset were included.

Results

Cerebellar acute vascular lesion occurred in 25/1,580 patients. All patients could complete the CCAS-S. A definite CCAS was evidenced in 21/25 patients. Patients failed 5.2 ± 2.12 items out of 8 and had a mean raw score of 68.2 ± 21.3 (normal values 82–120). Most failed items of the CCAS-S were related to verbal fluency, attention, and working memory.

Conclusion

A definite CCAS is present in almost all patients with acute cerebellar vascular lesions. CCAS is efficiently assessed by CCAS-S at bedside tests in acute stroke settings. The magnitude of CCAS likely reflects a cerebello-cortical diaschisis.

Preliminary Study of Vibrotactile Feedback during Home-Based Balance and Coordination Training in Individuals with Cerebellar Ataxia

Intensive balance and coordination training is the mainstay of treatment for symptoms of impaired balance and mobility in individuals with hereditary cerebellar ataxia. In this study, we compared the effects of home-based balance and coordination training with and without vibrotactile SA for individuals with hereditary cerebellar ataxia. Ten participants (five males, five females; 47  ±  12 years) with inherited forms of cerebellar ataxia were recruited to participate in a 12-week crossover study during which they completed two six-week blocks of balance and coordination training with and without vibrotactile SA. Participants were instructed to perform balance and coordination exercises five times per week using smartphone balance trainers that provided written, graphic, and video guidance and measured trunk sway. The pre-, per-, and post-training performance were assessed using the Scale for the Assessment and Rating of Ataxia (SARA), SARAposture&gait sub-scores, Dynamic Gait Index, modified Clinical Test of Sensory Interaction in Balance, Timed Up and Go performed with and without a cup of water, and multiple kinematic measures of postural sway measured with a single inertial measurement unit placed on the participants’ trunks. To explore the effects of training with and without vibrotactile SA, we compared the changes in performance achieved after participants completed each six-week block of training. Among the seven participants who completed both blocks of training, the change in the SARA scores and SARAposture&gait sub-scores following training with vibrotactile SA was not significantly different from the change achieved following training without SA (p>0.05). However, a trend toward improved SARA scores and SARAposture&gait sub-scores was observed following training with vibrotactile SA; compared to their pre-vibrotacile SA training scores, participants significantly improved their SARA scores (mean=−1.21, p=0.02) and SARAposture&gait sub-scores (mean=−1.00, p=0.01). In contrast, no significant changes in SARA scores and SARAposture&gait sub-scores were observed following the six weeks of training without SA compared to their pre-training scores immediately preceding the training block without vibrotactile SA (p>0.05). No significant changes in trunk kinematic sway parameters were observed as a result of training (p>0.05). Based on the findings from this preliminary study, balance and coordination training improved the participants’ motor performance, as captured through the SARA. Vibrotactile SA may be a beneficial addition to training regimens for individuals with hereditary cerebellar ataxia, but additional research with larger sample sizes is needed to assess the significance and generalizability of these findings.

The CCAS-scale in hereditary ataxias: helpful on the group level, particularly in SCA3, but limited in individual patients

Background

A brief bedside test has recently been introduced by Hoche et al. (Brain, 2018) to screen for the Cerebellar Cognitive Affective Syndrome (CCAS) in patients with cerebellar disease.

Objective

This multicenter study tested the ability of the CCAS-Scale to diagnose CCAS in individual patients with common forms of hereditary ataxia.

Methods

A German version of the CCAS-Scale was applied in 30 SCA3, 14 SCA6 and 20 FRDA patients, and 64 healthy participants matched for age, sex, and level of education. Based on original cut-off values, the number of failed test items was assessed, and CCAS was considered possible (one failed item), probable (two failed items) or definite (three failed items). In addition a total sum raw score was calculated.

Results

On a group level, failed items were significantly higher and total sum scores were significantly lower in SCA3 patients compared to matched controls. SCA6 and FRDA patients performed numerically below controls, but respective group differences failed to reach significance. The ability of the CCAS-Scale to diagnose CCAS in individual patients was limited to severe cases failing three or more items. Milder cases failing one or two items showed a great overlap with the performance of controls exhibiting a substantial number of false-positive test results. The word fluency test items differentiated best between patients and controls.

Conclusions

As a group, SCA3 patients performed below the level of SCA6 and FRDA patients, possibly reflecting additional cerebral involvement. Moreover, the application of the CCAS-Scale in its present form results in a high number of false-positive test results, that is identifying controls as patients, reducing its usefulness as a screening tool for CCAS in individual patients.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00415-022-11071-5.

Recessive cerebellar and afferent ataxias - clinical challenges and future directions

Cerebellar and afferent ataxias present with a characteristic gait disorder that reflects cerebellar motor dysfunction and sensory loss. These disorders are a diagnostic challenge for clinicians because of the large number of acquired and inherited diseases that cause cerebellar and sensory neuron damage. Among such conditions that are recessively inherited, Friedreich ataxia and RFC1-associated cerebellar ataxia, neuropathy, vestibular areflexia syndrome (CANVAS) include the characteristic clinical, neuropathological and imaging features of ganglionopathies, a distinctive non-length-dependent type of sensory involvement. In this Review, we discuss the typical and atypical phenotypes of Friedreich ataxia and CANVAS, along with the features of other recessive ataxias that present with a ganglionopathy or polyneuropathy, with an emphasis on recently described clinical features, natural history and genotype-phenotype correlations. We review the main developments in understanding the complex pathology that affects the sensory neurons and cerebellum, which seem to be most vulnerable to disorders that affect mitochondrial function and DNA repair mechanisms. Finally, we discuss disease-modifying therapeutic advances in Friedreich ataxia, highlighting the most promising candidate molecules and lessons learned from previous clinical trials.

The cognitive profile of Friedreich ataxia: a systematic review and meta-analysis

BACKGROUND

Study the cognitive profile of individuals with Friedreich ataxia (FRDA) and seek evidence for correlations between clinical, genetic and imaging characteristics and neuropsychological impairments.

METHODS

Based on PRISMA guidelines, a meta-analysis was realized using the Pubmed and Scopus databases to identify studies (1950-2021) reporting neuropsychological test results in genetically confirmed FRDA and control participants in at least one of the following cognitive domains: attention/executive, language, memory and visuo-spatial functions as well as emotion. Studies using identical outcomes in a minimum of two studies were pooled. Pooled effect sizes were calculated with Cohen's d.

RESULTS

Eighteen studies were included. Individuals with FRDA displayed significantly lower performance than individuals without FRDA in most language, attention, executive function, memory visuospatial function, emotion regulation and social cognitive tasks. Among the included studies, thirteen studies examined the relationship between neuropsychological test results and clinical parameters and reported significant association with disease severity and six studies reviewed the relationship between neuroimaging measures and cognitive performance and mainly reported links between reduced cognitive performance and changes in cerebellar structure.

CONCLUSIONS

Individuals with FRDA display significantly lower performances in many cognitive domains compared to control participants. The spectrum of the cognitive profile alterations in FRDA and its correlation with disease severity and cerebellar structural parameters suggest a cerebellar role in the pathophysiology of FRDA cognitive impairments.

Feasibility of Targeted Delivery of AAV5-GFP into the Cerebellum of Nonhuman Primates Following a Single Convection-Enhanced Delivery Infusion

In this study, we built upon our previous work to demonstrate the distribution and transport of AAV5-green fluorescent protein (GFP) following a single convection-enhanced delivery infusion into the nonhuman primate cerebellum, with no untoward side effects noted. Dosing under magnetic resonance imaging guidance revealed a sixfold larger volume of distribution compared with the volume of infusion, with no evidence of reflux underscoring the convective properties of the cerebellum and step design of the cannula. Postmortem tissue analysis, 4 weeks post-adeno-associated viral (AAV) delivery, revealed the robust presence of the transgene in situ, with GFP detection in secondary regions not directly targeted by the infusion, denoting distal transport of the vector. Irrespective of tropism, a twofold larger area of transgene expression was found and was corroborated against the presence of contrast on T1-weighted images. Different levels of transduction were detected between animals, which were negatively correlated with the level of antibody titer against the GFP construct, whereby the higher the antibody titer, the lower the level of transgene expression. These findings support the use of the posterior fossa as a potential target site for direct delivery of gene-based therapeutics for cerebellar diseases.

The cerebellar cognitive affective syndrome scale reveals early neuropsychological deficits in SCA3 patients

BACKGROUND

The cerebellar cognitive affective syndrome scale (CCAS-S) was recently developed to detect specific neuropsychological deficits in patients with cerebellar diseases in an expedited manner.

OBJECTIVES

To evaluate the discriminative ability of the CCAS-S in an etiologically homogeneous cohort of spinocerebellar ataxia type 3 (SCA3) patients and to examine relationships between cognitive deficits and motor symptom severity.

METHODS

The CCAS-S was administered to twenty mildly to moderately affected SCA3 patients and eighteen healthy controls matched for age, sex, and educational level. Disease severity was measured by the Scale for the Assessment and Rating of Ataxia (SARA), Inventory of Non-Ataxia Signs (INAS), 8 m walk test, nine-hole peg test (9HPT), and Patient Health Questionnaire-9 (PHQ-9).

RESULTS

SCA3 patients had a lower total CCAS-S score (p < 0.001) and higher number of failed tests (p = 0.006) than healthy controls. Patients displayed impairments in semantic fluency, phonemic fluency, category switching, cube drawing, and affect regulation. Total CCAS-S score showed high discriminative ability (area under the curve [AUC]: 0.96) and was associated with disease duration, SARA score, walking speed, and dominant hand 9HPT performance. No correlations were observed with INAS count, repeat length, and PHQ-9 score. Discriminative capacity of the number of failed tests was moderate (AUC: 0.76).

CONCLUSION

Essentially all SCA3 patients exhibited some form of cognitive impairment. The CCAS-S differentiates SCA3 patients from healthy controls, detects neuropsychological deficits early in the disease course, and correlates with relevant ataxia severity measures.

Central Nervous System Therapeutic Targets in Friedreich Ataxia

Friedreich ataxia (FRDA) is an autosomal recessive inherited multisystem disease, characterized by marked differences in the vulnerability of neuronal systems. In general, the proprioceptive system appears to be affected early, while later in the disease, the dentate nucleus of the cerebellum and, to some degree, the corticospinal tracts degenerate. In the current era of expanding therapeutic discovery in FRDA, including progress toward novel gene therapies, a deeper and more specific consideration of potential treatment targets in the nervous system is necessary. In this work, we have re-examined the neuropathology of FRDA, recognizing new issues superimposed on classical findings, and dissected the peripheral nervous system (PNS) and central nervous system (CNS) aspects of the disease and the affected cell types. Understanding the temporal course of neuropathological changes is needed to identify areas of modifiable disease progression and the CNS and PNS locations that can be targeted at different time points. As most major targets of long-term therapy are in the CNS, this review uses multiple tools for evaluation of the importance of specific CNS locations as targets. In addition to clinical observations, the conceptualizations in this study include physiological, pathological, and imaging approaches, and animal models. We believe that this review, through analysis of a more complete set of data derived from multiple techniques, provides a comprehensive summary of therapeutic targets in FRDA.

Brain Structure and Degeneration Staging in Friedreich Ataxia: Magnetic Resonance Imaging Volumetrics from the ENIGMA-Ataxia Working Group

Objective

Friedreich ataxia (FRDA) is an inherited neurological disease defined by progressive movement incoordination. We undertook a comprehensive characterization of the spatial profile and progressive evolution of structural brain abnormalities in people with FRDA.

Methods

A coordinated international analysis of regional brain volume using magnetic resonance imaging data charted the whole‐brain profile, interindividual variability, and temporal staging of structural brain differences in 248 individuals with FRDA and 262 healthy controls.

Results

The brainstem, dentate nucleus region, and superior and inferior cerebellar peduncles showed the greatest reductions in volume relative to controls (Cohen d = 1.5–2.6). Cerebellar gray matter alterations were most pronounced in lobules I–VI (d = 0.8), whereas cerebral differences occurred most prominently in precentral gyri (d = 0.6) and corticospinal tracts (d = 1.4). Earlier onset age predicted less volume in the motor cerebellum (r_max = 0.35) and peduncles (r_max = 0.36). Disease duration and severity correlated with volume deficits in the dentate nucleus region, brainstem, and superior/inferior cerebellar peduncles (r_max = −0.49); subgrouping showed these to be robust and early features of FRDA, and strong candidates for further biomarker validation. Cerebral white matter abnormalities, particularly in corticospinal pathways, emerge as intermediate disease features. Cerebellar and cerebral gray matter loss, principally targeting motor and sensory systems, preferentially manifests later in the disease course.

Interpretation

FRDA is defined by an evolving spatial profile of neuroanatomical changes beyond primary pathology in the cerebellum and spinal cord, in line with its progressive clinical course. The design, interpretation, and generalization of research studies and clinical trials must consider neuroanatomical staging and associated interindividual variability in brain measures. ANN NEUROL 2021;90:570–583

Cognitive Decline Is Closely Associated with Ataxia Severity in Spinocerebellar Ataxia Type 2: a Validation Study of the Schmahmann Syndrome Scale

The cerebellar cognitive affective syndrome scale (CCAS-S) was designed to detect specific cognitive dysfunctions in cerebellar patients but is scarcely validated in spinocerebellar ataxias (SCA). The objective of this study is to determine the usefulness of the CCAS-S in a Cuban cohort of SCA2 patients and the relationship of its scores with disease severity. The original scale underwent a forward and backward translation into Spanish language, followed by a pilot study to evaluate its comprehensibility. Reliability, discriminant, and convergent validity assessments were conducted in 64 SCA2 patients and 64 healthy controls matched for sex, age, and education. Fifty patients completed the Montreal Cognitive Assessment (MoCA) test. The CCAS-S showed an acceptable internal consistency (Cronbach's alpha = 0.74) while its total raw score and the number of failed tests showed excellent (ICC = 0.94) and good (ICC = 0.89) test-retest reliability, respectively. Based on original cut-offs, the sensitivity of CCAS-S to detect possible/probable/definite CCAS was notably high (100%/100%/91%), but specificities were low (6%/30/64%) because the decreased specificity observed in four items. CCAS-S performance was significantly influenced by ataxia severity in patients and by education in both groups. CCAS-S scores correlated with MoCA scores, but showed higher sensitivity than MoCA to detect cognitive impairments in patients. The CCAS-S is particularly useful to detect cognitive impairments in SCA2 but some transcultural and/or age and education-dependent adaptations could be necessary to improve its diagnostic properties. Furthermore, this scale confirmed the parallelism between cognitive and motor deficits in SCA2, giving better insights into the disease pathophysiology and identifying novel outcomes for clinical trials.

Friedreich Ataxia: Multidisciplinary Clinical Care

Friedreich ataxia (FRDA) is a multisystem disorder affecting 1 in 50,000-100,000 person in the United States. Traditionally viewed as a neurodegenerative disease, FRDA patients also develop cardiomyopathy, scoliosis, diabetes and other manifestation. Although it usually presents in childhood, it continues throughout life, thus requiring expertise from both pediatric and adult subspecialist in order to provide optimal management. The phenotype of FRDA is unique, giving rise to specific loss of neuronal pathways, a unique form of cardiomyopathy with early hypertrophy and later fibrosis, and diabetes incorporating components of both type I and type II disease. Vision loss, hearing loss, urinary dysfunction and depression also occur in FRDA. Many agents are reaching Phase III trials; if successful, these will provide a variety of new treatments for FRDA that will require many specialists who are not familiar with FRDA to provide clinical therapy. This review provides a summary of the diverse manifestation of FRDA, existing symptomatic therapies, and approaches for integrative care for future therapy in FRDA.

Cognitive impairment and affective disorder: A rare presentation of cerebellar stroke

The awareness of the "Cerebellar Cognitive Affective Syndrome" (CCAS) as a clinical entity is emerging. The CCAS is characterized by impaired executive functions, linguistic skills, visuospatial cognition and personality change. Here we report a 56-year-old, male teacher who developed acute psychomotor retardation, low energy level, infrequent speech, and mild cognitive decline. Two months before admission, he was initially diagnosed as depression, and later misdiagnosed as encephalitis, which misled him to receive high-dose intravenous steroids and antimicrobial drugs. The Brain MRI revealed multiple posterior cerebellar infarcts predominantly at the lobules VII and VIII. The standard neuropsychological tests were unremarkable; however, the CCAS Scale confirmed the diagnosis. The treatment of depression and secondary prevention of stroke was conducted. In cases that present with features of cognitive and affective disorders but with mild voluntary motor or without typical cerebellar features, the role of posterior cerebellar and vermian pathologies should be considered. The CCAS Scale is an appropriate screening tool to detect these patients and provides a framework for evidence-based treatment.

The cerebellar cognitive affective syndrome scale reveals early neuropsychological deficits in SCA3 patients

Background

The cerebellar cognitive affective syndrome scale (CCAS-S) was recently developed to detect specific neuropsychological deficits in patients with cerebellar diseases in an expedited manner.

Objectives

To evaluate the discriminative ability of the CCAS-S in an etiologically homogeneous cohort of spinocerebellar ataxia type 3 (SCA3) patients and to examine relationships between cognitive deficits and motor symptom severity.

Methods

The CCAS-S was administered to twenty mildly to moderately affected SCA3 patients and eighteen healthy controls matched for age, sex, and educational level. Disease severity was measured by the Scale for the Assessment and Rating of Ataxia (SARA), Inventory of Non-Ataxia Signs (INAS), 8 m walk test, nine-hole peg test (9HPT), and Patient Health Questionnaire-9 (PHQ-9).

Results

SCA3 patients had a lower total CCAS-S score (p < 0.001) and higher number of failed tests (p = 0.006) than healthy controls. Patients displayed impairments in semantic fluency, phonemic fluency, category switching, cube drawing, and affect regulation. Total CCAS-S score showed high discriminative ability (area under the curve [AUC]: 0.96) and was associated with disease duration, SARA score, walking speed, and dominant hand 9HPT performance. No correlations were observed with INAS count, repeat length, and PHQ-9 score. Discriminative capacity of the number of failed tests was moderate (AUC: 0.76).

Conclusion

Essentially all SCA3 patients exhibited some form of cognitive impairment. The CCAS-S differentiates SCA3 patients from healthy controls, detects neuropsychological deficits early in the disease course, and correlates with relevant ataxia severity measures.

Cerebellar ataxia and exercise intolerance in Erdheim-Chester disease

Background

Erdheim-Chester disease (ECD), a rare disorder of monocyte/macrophage lineage, has been related to cerebellar dysfunction. To increase the awareness of this rare, protean disease, an unusual, myasthenia-like onset of ECD is reported.

Case presentation

A 42-year-old man presented with a 6-year history of mild evening fatigability in his four limbs followed by motor and cognitive symptoms associated with cerebellar atrophy, dentate nuclei and dentato-thalamic pathway degeneration. Magnetic resonance imaging revealed hyperintense signals in T2 and fluid-attenuated inversion recovery sequences within the pons, cerebellar white matter, dentate nuclei and globi pallidi in the absence of any contrast enhancement. Whole-body bone scintigraphy with ⁹⁹Technetium - methylene diphosphonate and fluorodeoxyglucose-positron emission tomography both revealed symmetric uptake in the lower extremities a finding suggestive of a diagnosis of ECD. Histological examination revealed diffuse infiltration of CD 68⁺ histiocytes with foamy cytoplasms in the presence of B-type of Rapidly Accelerated Fibrosarcoma protein kinase (BRAF)^V600E activating mutation in tumor cells.

Conclusion

In patients with myasthenia-like symptoms who test negatively for myasthenia gravis, neurodegenerative diseases, and disorders of the hypothalamus, a diagnosis of ECD should be taken into consideration.

Antisense Transcription across Nucleotide Repeat Expansions in Neurodegenerative and Neuromuscular Diseases: Progress and Mysteries

Unstable repeat expansions and insertions cause more than 30 neurodegenerative and neuromuscular diseases. Remarkably, bidirectional transcription of repeat expansions has been identified in at least 14 of these diseases. More remarkably, a growing number of studies has been showing that both sense and antisense repeat RNAs are able to dysregulate important cellular pathways, contributing together to the observed clinical phenotype. Notably, antisense repeat RNAs from spinocerebellar ataxia type 7, myotonic dystrophy type 1, Huntington's disease and frontotemporal dementia/amyotrophic lateral sclerosis associated genes have been implicated in transcriptional regulation of sense gene expression, acting either at a transcriptional or posttranscriptional level. The recent evidence that antisense repeat RNAs could modulate gene expression broadens our understanding of the pathogenic pathways and adds more complexity to the development of therapeutic strategies for these disorders. In this review, we cover the amazing progress made in the understanding of the pathogenic mechanisms associated with repeat expansion neurodegenerative and neuromuscular diseases with a focus on the impact of antisense repeat transcription in the development of efficient therapies.