Cerebellar Ataxia Patients Research Articles

Anti-Sez6l2 antibodies, detected in the immune-mediated cerebellar ataxia patient, identify the extracellular domain of Sez6l2 and inhibit complex formation of GluR1, Sez6l2 and ADD

Background: The importance of central nervous system syndrome associated with neuronal surface antibodies has been increasing. A lot of studies suggested that disabling cerebellar ataxias may develop through immune-mediated mechanisms. We previously reported a new anti-neuronal antibody, anti-Sez6l2 antibody (Yaguchi et al. Journal of Neurology). Sez6l2 is highly expressed in the hippocampus and cerebellar cortex and is one of the type 1 membrane proteins.

Autoimmune cerebellar ataxia with initial seronegativity and low‐titer anti‐glutamic acid decarboxylase antibody in the cerebrospinal fluid

AbstractBackgroundIn cases with anti‐glutamic acid decarboxylase (GAD) antibody‐positive cerebellar ataxia, the titer of the antibody is usually very high. However, a few cases of low‐titer GAD antibody‐positive cerebellar ataxia patients have been described recently. In such patients, the antibody has been detected predominantly in serum, rather than in cerebrospinal fluid.Case presentationA 34‐year‐old man presented with subacute‐onset cerebellar ataxia, and examinations revealed no abnormal findings except low‐titer anti‐GAD antibody in the cerebrospinal fluid at initial evaluation: the serum antibody became slightly positive in a delayed manner. Treatment with steroid and/or immunoglobulin was effective in improving symptoms, and the effect of these treatments continued for approximately 1 year.ConclusionsThe present case suggested a potential diagnostic pitfall, in which the examination of serum anti‐GAD antibody at initial evaluation alone might be insufficient to rule out this disease. It may be indicated that the routine screening should include examination for the GAD antibody in both the serum and cerebrospinal fluid, plus additional follow‐up checks for the antibody in the subsequent clinical course. Care must be taken to avoid non‐detection of this disease with possibly reversible symptoms in patients with cerebellar ataxia of unknown origin.

Pathogenic Roles of Glutamic Acid Decarboxylase 65 Autoantibodies in Cerebellar Ataxias

Reports suggesting a pathogenic role of autoantibodies directed against glutamic acid decarboxylase 65 (GAD65Abs) in cerebellar ataxias (CAs) are reviewed, and debatable issues such as internalization of antibodies by neurons and roles of epitopes are discussed. GAD65 is one of two enzymes that catalyze the conversion of glutamate to the inhibitory neurotransmitter gamma-aminobutyric acid (GABA). A pathogenic role of GAD65Ab in CAs is suggested by in vivo and in vitro studies. (1) Intracerebellar administration of cerebrospinal fluid (CSF) immunoglobulins (IgGs) obtained from GAD65Ab-positive CA patients impairs cerebellar modulation of motor control in rats. (2) CSF IgGs act on terminals of GABAergic neurons and decrease the release of GABA in cerebellar slices from rats and mice. (3) Absorption of GAD65Ab by recombinant GAD65 diminishes the above effects, and monoclonal human GAD65Ab (b78) mimic the effects of CSF IgGs in vivo and in vitro. Studies using GAD65-KO mice confirm that the target molecule is GAD65. (4) Notably, the effects of GAD65Ab depend on the epitope specificity of the monoclonal GAD65Ab. Taken together, these results indicate that epitope-specific GAD65Ab-induced impairment of GABA release is involved in the pathogenesis of GAD65Ab-positive CA and support the early detection of GAD65Ab-associated CA to initiate immunotherapy before irreversible neuronal death in the cerebellum.

HiPSC Disease Modeling of Rare Hereditary Cerebellar Ataxias: Opportunities and Future Challenges

Cerebellar ataxias are clinically and genetically heterogeneous diseases affecting primary cerebellar cells. The lack of availability of affected tissue from cerebellar ataxias patients is the main obstacle in investigating the pathogenicity of these diseases. The landmark discovery of human-induced pluripotent stem cells (hiPSC) has permitted the derivation of patient-specific cells with an unlimited self-renewing capacity. Additionally, their potential to differentiate into virtually any cell type of the human organism allows for large amounts of affected cells to be generated in culture, converting this hiPSC technology into a revolutionary tool in the study of the mechanisms of disease, drug discovery, and gene correction. In this review, we will summarize the current studies in which hiPSC were utilized to study cerebellar ataxias. Describing the currently available 2D and 3D hiPSC-based cellular models, and due to the fact that extracerebellar cells were used to model these diseases, we will discuss whether or not they represent a faithful cellular model and whether they have contributed to a better understanding of disease mechanisms.

Clinical exome sequencing for cerebellar ataxia and spastic paraplegia uncovers novel gene-disease associations and unanticipated rare disorders.

Cerebellar ataxia (CA) and hereditary spastic paraplegia (HSP) are two of the most prevalent motor disorders with extensive locus and allelic heterogeneity. We implemented clinical exome sequencing, followed by filtering data for a ‘movement disorders' gene panel, as a generic test to increase variant detection in 76 patients with these disorders. Segregation analysis or phenotypic re-evaluation was utilized to substantiate findings. Disease-causing variants were identified in 9 of 28 CA patients, and 8 of 48 HSP patients. In addition, possibly disease-causing variants were identified in 1 and 8 of the remaining CA and HSP patients, respectively. In 10 patients with CA, the total disease-causing or possibly disease-causing variants were detected in 8 different genes, whereas 16 HSP patients had such variants in 12 different genes. In the majority of cases, the identified variants were compatible with the patient phenotype. Interestingly, in some patients variants were identified in genes hitherto related to other movement disorders, such as TH variants in two siblings with HSP. In addition, rare disorders were uncovered, for example, a second case of HSP caused by a VCP variant. For some patients, exome sequencing results had implications for treatment, exemplified by the favorable L-DOPA treatment in a patient with HSP due to ATP13A2 variants (Parkinson type 9). Thus, clinical exome sequencing in this cohort of CA and HSP patients suggests broadening of disease spectra, revealed novel gene–disease associations, and uncovered unanticipated rare disorders. In addition, clinical exome sequencing results have shown their value in guiding practical patient management.

Effects of Dual Tasks on Balance Ability in Patients with Cerebellar Ataxia

The purpose of this study was to examine the effects of dual tasks on balance and postural control during standing in patients with cerebellar ataxia (CA). It was hypothesized that CA patients would exhibit different sway characteristics of the center of mass (COM) depending on the complexity of the secondary cognitive tasks compared with normal control subjects.

Characteristic diffusion tensor tractography in multiple system atrophy with predominant cerebellar ataxia and cortical cerebellar atrophy.

The objective of this study is to determine whether diffusion tensor imaging (DTI) tractography analysis is a potential method for differentiating cerebellar ataxia patients with multiple system atrophy with predominant cerebellar ataxia (MSA-C) and cortical cerebellar atrophy (CCA). Forty-one MSA-C patients (62.7 ± 8.1 years old, mean ± SD) and age- and gender-matched 15 CCA patients (63.0 ± 8.6 years old) were examined.Tractography was performed using the DTI track module provided in the MedINRIA version 1.9.4, and regions of interest were drawn manually to reconstruct an efferent fiber tract and two afferent fiber tracts via the cerebellum. Compared with CCA, MSA-C patients showed significant declines of fractional anisotropy (FA) values of afferent 1 and 2 (p<0.01, respectively) and a significant increase of the radial diffusivity (RD) value in afferent 1 (p<0.05). Receiver-operator characteristic curve analysis showed 85.7 % sensitivity and 75.0 % specificity of FA values in afferent 1 (cutoff value 0.476). Linear regressions showed strong correlations between FA value and disease duration in CCA patients (efferent 1, r = -0.466; afferent 2, r = -0.543; both p<0.05), and between the FA value and the ratio of the standardized scale for the assessment and rating of ataxia (SARA)/disease duration in MSA-C patients (afferent 1, r = -0.407; p<0.01). The present DTI tractography newly showed that the FA values of two afferent fiber tracts showed significant declines in MSA-C patients, and afferent 1 showed good diagnostic sensitivity and specificity. When combining the FA values of efferent 1 with disease duration, the present DTI tractography analysis could be useful for differentiating MSA-C and CCA patients.

Interpretable exemplar-based shape classification using constrained sparse linear models.

Many types of diseases manifest themselves as observable changes in the shape of the affected organs. Using shape classification, we can look for signs of disease and discover relationships between diseases. We formulate the problem of shape classification in a holistic framework that utilizes a lossless scalar field representation and a non-parametric classification based on sparse recovery. This framework generalizes over certain classes of unseen shapes while using the full information of the shape, bypassing feature extraction. The output of the method is the class whose combination of exemplars most closely approximates the shape, and furthermore, the algorithm returns the most similar exemplars along with their similarity to the shape, which makes the result simple to interpret. Our results show that the method offers accurate classification between three cerebellar diseases and controls in a database of cerebellar ataxia patients. For reproducible comparison, promising results are presented on publicly available 2D datasets, including the ETH-80 dataset where the method achieves 88.4% classification accuracy.

Functional analysis helps to define KCNC3 mutational spectrum in Dutch ataxia cases.

Spinocerebellar ataxia type 13 (SCA13) is an autosomal dominantly inherited neurodegenerative disorder of the cerebellum caused by mutations in the voltage gated potassium channel KCNC3. To identify novel pathogenic SCA13 mutations in KCNC3 and to gain insights into the disease prevalence in the Netherlands, we sequenced the entire coding region of KCNC3 in 848 Dutch cerebellar ataxia patients with familial or sporadic origin. We evaluated the pathogenicity of the identified variants by co-segregation analysis and in silico prediction followed by biochemical and electrophysiological studies. We identified 19 variants in KCNC3 including 2 non-coding, 11 missense and 6 synonymous variants. Two missense variants did not co-segregate with the disease and were excluded as potentially disease-causing mutations. We also identified the previously reported p.R420H and p.R423H mutations in our cohort. Of the remaining 7 missense variants, functional analysis revealed that 2 missense variants shifted Kv3.3 channel activation to more negative voltages. These variations were associated with early disease onset and mild intellectual disability. Additionally, one other missense variant shifted channel activation to more positive voltages and was associated with spastic ataxic gait. Whereas, the remaining missense variants did not change any of the channel characteristics. Of these three functional variants, only one variant was in silico predicted to be damaging and segregated with disease. The other two variants were in silico predicted to be benign and co-segregation analysis was not optimal or could only be partially confirmed. Therefore, we conclude that we have identified at least one novel pathogenic mutation in KCNC3 that cause SCA13 and two additionally potential SCA13 mutations. This leads to an estimate of SCA13 prevalence in the Netherlands to be between 0.6% and 1.3%.

Hilbert-Huang transform analysis of somatosensory and motor evoked potential for intraoperative neurophysiologic monitoring

Introduction: Motor surround inhibition (mSI) has been proposed in the selectively execute desired motor programs. The cerebellum play important role in motor control and co-ordination of movements. The aim of the study is to research the relationship with disrupted mSI and function of central nervous system during motor performance using functional MRI in patients with cerebellar ataxia. Methods and Patients: Seven healthy subjects (mean ages 34.7 9.1 years, all men) and seven patients with pure cerebellar ataxia (mean ages 60.7 11.9 years, 4 men and 3 women, six patients with SCA6, one SCA31 patient) were enrolled. Surrounding inhibition study: The experiment of surround inhibition was done according to S.Beck and M.Hallett. The EMG were recorded in both right FDI and APB. mSI was evaluated as the ratio of MEP size of APB to that of FDI. MEPs were measured by using single TMS which was given before signal and 100ms, 150ms and 1200ms after signal. Functional magnetic imaging for task and testing procedures: Each subject participated in two sessions during they performed righthand tapping. Results: In normal subjects, significant mSI was found within 150ms after finger tapping. However, FHD showed no SI during finger tapping. The finding of fMRI showed hyperactivity of motor area and excessive activation in prefrontal area. And also hyperactivity is observed in both cerebellar hemispheres. Discussion: In normal subjects, significant mSI was observed within 150ms. Functional MRI showed significant activation in cerebellum during tasks. In cerebellar ataxia patients, mSI study showed loss of surround inhibition of finger movement. Hypoactivation of cerebellum was observed in fMRI. These findings suggest that cerebellum may have some contribute to the generation of mSI.

Disturbed motor surround inhibition and cerebellar hypo-activation of functional MRI in patients with cerebellar ataxia

Introduction: Motor surround inhibition (mSI) has been proposed in the selectively execute desired motor programs. The cerebellum play important role in motor control and co-ordination of movements. The aim of the study is to research the relationship with disrupted mSI and function of central nervous system during motor performance using functional MRI in patients with cerebellar ataxia. Methods and Patients: Seven healthy subjects (mean ages 34.7 9.1 years, all men) and seven patients with pure cerebellar ataxia (mean ages 60.7 11.9 years, 4 men and 3 women, six patients with SCA6, one SCA31 patient) were enrolled. Surrounding inhibition study: The experiment of surround inhibition was done according to S.Beck and M.Hallett. The EMG were recorded in both right FDI and APB. mSI was evaluated as the ratio of MEP size of APB to that of FDI. MEPs were measured by using single TMS which was given before signal and 100ms, 150ms and 1200ms after signal. Functional magnetic imaging for task and testing procedures: Each subject participated in two sessions during they performed righthand tapping. Results: In normal subjects, significant mSI was found within 150ms after finger tapping. However, FHD showed no SI during finger tapping. The finding of fMRI showed hyperactivity of motor area and excessive activation in prefrontal area. And also hyperactivity is observed in both cerebellar hemispheres. Discussion: In normal subjects, significant mSI was observed within 150ms. Functional MRI showed significant activation in cerebellum during tasks. In cerebellar ataxia patients, mSI study showed loss of surround inhibition of finger movement. Hypoactivation of cerebellum was observed in fMRI. These findings suggest that cerebellum may have some contribute to the generation of mSI.

Treatment of Neurodegenerative Ataxias With Intravenous Immune Globulin

Background: Neurodegenerative ataxias, including spinocerebellar ataxias (SCAs), are progressive diseases without effective treatment. There is preclinical evidence that inflammation may contribute to neuronal injury in several neurodegenerative ataxias. Intravenous immune globulin (IVIG) is a therapeutic modality that is used as treatment of several autoimmune and inflammatory disorders. Methods: The primary objective of this open-label pilot study was to assess the effect of IVIG on neurodegenerative ataxias as measured by total scale for the assessment and rating of ataxia (SARA) score. Three patients received IVIG (2 g/kg of body weight, divided over 5 days) once monthly for 3 months, and were evaluated before the first infusion, 2 weeks after each infusion, as well as 28 and 56 days following the final course of treatment. Secondary measures included SARA subsection scores and gait assessment using the GAITRite ® Walkway System. Another SCA 3 patient at a different site was treated with six monthly courses of IVIG, and assessed with the SARA score. Results: Three out of five patients completed the open-label study (SCA 3, a neurodegenerative ataxia associated with an aprataxin genetic variant, and late onset cerebellar ataxia (LOCA) patient). All three patients demonstrated improvement in the SARA score following IVIG. SARA total scores improved by 30-50% and gait sub-scores improved by 20-50% after the last course of IVIG. Clinical improvements attenuated approximately 2 months following the last infusion. The SCA 3 patient treated at another site with a longer protocol had even greater improvement in the SARA score. Conclusions: IVIG may have therapeutic efficacy in neurodegen erative ataxias, including SCA and LOCA.

Reversible Cerebellar Ataxia Related to Extrapontine Myelinolysis without Hyponatremia after Cisplatin-Based Chemotherapy for Cholangiocarcinoma.

A 60-year-old woman presented with cerebellar signs including dysarthria and ataxia, after intravenous infusion of cisplatin-based chemotherapy. Several blood tests showed mild neutropenia, normocytic normochromic anemia, but no evidence of a marked hyponatremia. Brain magnetic resonance imaging with diffusion-weighted sequences showed hyper-intense signal abnormalities in the extrapontine region, sparing the basis pontis. Here, we report on the case of a patient with reversible cerebellar ataxia related to extrapontine myelinolysis without hyponatremia after treatment with cisplatin-based chemotherapy for cholangiocarcinoma and discuss the literature on cerebellar ataxia in patients who underwent recent chemotherapy for malignancy.

Glutamate receptor antibodies in neurological diseases: anti-AMPA-GluR3 antibodies, anti-NMDA-NR1 antibodies, anti-NMDA-NR2A/B antibodies, anti-mGluR1 antibodies or anti-mGluR5 antibodies are present in subpopulations of patients with either: epilepsy, encephalitis, cerebellar ataxia, systemic lupus erythematosus (SLE) and neuropsychiatric SLE, Sjogren's syndrome, schizophrenia, mania or stroke. These autoimmune anti-glutamate receptor antibodies can bind neurons in few brain regions, activate glutamate receptors, decrease glutamate receptor's

Glutamate receptor antibodies in neurological diseases: anti-AMPA-GluR3 antibodies, anti-NMDA-NR1 antibodies, anti-NMDA-NR2A/B antibodies, anti-mGluR1 antibodies or anti-mGluR5 antibodies are present in subpopulations of patients with either: epilepsy, encephalitis, cerebellar ataxia, systemic lupus erythematosus (SLE) and neuropsychiatric SLE, Sjogren's syndrome, schizophrenia, mania or stroke. These autoimmune anti-glutamate receptor antibodies can bind neurons in few brain regions, activate glutamate receptors, decrease glutamate receptor's

JC Polyomavirus Granule Cell Neuronopathy in a Patient Treated With Rituximab

Progressive multifocal leukoencephalopathy results from lytic infection of the glia by the JC polyomavirus (JCV); JCV granule cell neuronopathy is caused by infection with a mutated form of JCV, leading to a shift in viral tropism from the glia to cerebellar granule cells. This shift results in a clinical syndrome dominated by progressive cerebellar dysfunction that might elude standard diagnostic workup strategies for ataxia. We present the case report of a patient receiving long-term rituximab therapy who developed progressive cerebellar ataxia and marked isolated cerebellar degeneration. This syndrome resulted from JCV granule cell neuronopathy associated with a novel JCV mutation. New onset or worsening of isolated cerebellar ataxia in patients being treated with rituximab or natalizumab warrants early assessment for JCV infection.

Antiphospholipid Antibodies and Cerebellar Ataxia: A Clinical Analysis and Literature Review

Background: Although it has been established that antiphospholipid antibodies (APAbs) bind to and modulate the signaling of cerebellar neurons in vitro, the clinical correlation between increased APAbs and cerebellar ataxia has rarely been investigated. Methods: We reviewed 10 patients presenting with cerebellar ataxia with increased blood APAbs from our database along with 3 APAb-associated cerebellar ataxia patients in the literature. Results: Of these 10 patients, 4 exhibited a subacute onset of progressive ataxia, and there were no significant structural changes in their brains that appeared to be responsible for the symptoms. Another 6 showed a chronic course of ataxia, and shared similar morphological changes that included symmetrical lesions in bilateral hemispheres, periventricular lucency and central and temporal atrophy of varying severity; the cerebellum was spared. The predominant APAbs for subacute and chronic ataxia were the anti-beta₂-glycoprotein I antibody and anticardiolipin antibody, respectively. Cancer was found in 1 patient with subacute ataxia and in 4 with chronic ataxia. The removal of the cancer, the plasmapheresis and immunosuppressive therapy successfully abolished the ataxia and increased APAb levels in all 5 patients. Conclusions: The relation between APAbs and nonvascular neurological disorders, such as cerebellar ataxia, should be further studied. APAbs may mediate neurological deficits via different mechanisms such as structural damage or functional neurotoxicity. Clinically, the examination of blood APAb levels is recommended for patients with cerebellar ataxia without a determined cause, and the further survey of systemic cancers in the case of APAb positivity is also recommended. Finally, plasmapheresis is a reasonable and effective treatment for APAb-associated cerebellar ataxia.

Treatment of Neurodegenerative Ataxias With Intravenous Immune Globulin

Background: Neurodegenerative ataxias, including spinocerebellar ataxias (SCAs), are progressive diseases without effective treatment. There is preclinical evidence that inflammation may contribute to neuronal injury in several neurodegenerative ataxias. Intravenous immune globulin (IVIG) is a therapeutic modality that is used as treatment of several autoimmune and inflammatory disorders. Methods: The primary objective of this open-label pilot study was to assess the effect of IVIG on neurodegenerative ataxias as measured by total scale for the assessment and rating of ataxia (SARA) score. Three patients received IVIG (2 g/kg of body weight, divided over 5 days) once monthly for 3 months, and were evaluated before the first infusion, 2 weeks after each infusion, as well as 28 and 56 days following the final course of treatment. Secondary measures included SARA subsection scores and gait assessment using the GAITRite ® Walkway System. Another SCA 3 patient at a different site was treated with six monthly courses of IVIG, and assessed with the SARA score. Results: Three out of five patients completed the open-label study (SCA 3, a neurodegenerative ataxia associated with an aprataxin genetic variant, and late onset cerebellar ataxia (LOCA) patient). All three patients demonstrated improvement in the SARA score following IVIG. SARA total scores improved by 30-50% and gait sub-scores improved by 20-50% after the last course of IVIG. Clinical improvements attenuated approximately 2 months following the last infusion. The SCA 3 patient treated at another site with a longer protocol had even greater improvement in the SARA score. Conclusions: IVIG may have therapeutic efficacy in neurodegen erative ataxias, including SCA and LOCA.

Increased gait variability is associated with the history of falls in patients with cerebellar ataxia

Falls are common in patients with cerebellar ataxia (CA). Identification of gait variables associated with a higher risk of falls allows us to detect fallers and initiate protective procedures early. Gait variability, which is increased in CA patients, is a good predictor of falls in elderly subjects and patients with neurodegenerative diseases. The relationship between gait variability and fall risk in patients with different cerebellar disorders was systematically investigated. A total of 48 patients with different cerebellar ataxia entities [adult-onset cerebellar atrophy (SAOA) (n = 23), unknown entity (n = 7), vascular (n = 5), post-cerebellitis (n = 6), congenital (n = 2), Louis-Bar syndrome (n = 2), ethyltoxic (n = 2) posttraumatic (n = 1)] were examined using a GAITRite® sensor mat. Spatial and temporal variability parameters were used for ANOVA testing and logistic regression models with categorized fall events as dependent variables. Gait variability in the fore-aft direction showed significant differences between the fall groups (p < 0.05-0.01). Model effects were highest for walking with slow speed (correct prediction 0.50-0.72). The speed-dependent integral of gait variability markers showed a higher discriminatory power (correct prediction 0.74-0.94). Gait variability is linked to the fall risk of patients with CA, slow walking and temporal gait variability being most relevant. The use of speed-dependent integrals of gait variability improves the accuracy of fall prediction. To predict fall risks in cerebellar ataxia, gait variability measurements made during slow walking should be included in a gait analysis procedure. The effects of speed-adjusted physiotherapeutic interventions have to be further investigated.

Lower Limb Antagonist Muscle Co-Activation and its Relationship with Gait Parameters in Cerebellar Ataxia

Increased antagonist muscle co-activation, seen in motor-impaired individuals, is an attempt by the neuromuscular system to provide mechanical stability by stiffening joints. The aim of this study was to investigate the co-activation pattern of the antagonist muscles of the ankle and knee joints during walking in patients with cerebellar ataxia, a neurological disease that strongly affects stability. Kinematic and electromyographic parameters of gait were recorded in 17 patients and 17 controls. Ankle and knee antagonist muscle co-activation indexes were measured throughout the gait cycle and during the sub-phases of gait. The indexes of ataxic patients were compared with those of controls and correlated with clinical and gait variables. Patients showed increased co-activity indexes of both ankle and knee muscles during the gait cycle as well as during the gait sub-phases. Both knee and ankle muscle co-activation indexes were positively correlated with disease severity, while ankle muscle co-activation was also positively correlated with stance and swing duration variability. Significant negative correlations were observed between the number of self-reported falls per year and knee muscle co-activation. The increased co-activation observed in these cerebellar ataxia patients may represent a compensatory strategy serving to reduce gait instability. Indeed, this mechanism allows patients to reduce the occurrence of falls. The need for this strategy, which results in excessive muscle co-contraction, increased metabolic costs and cartilage degeneration processes, could conceivably be overcome through the use of supportive braces specially designed to provide greater joint stability.

Spinocerebellar Ataxia Type 2 Neurodegeneration Differentially Affects Error-Based and Strategic-Based Visuomotor Learning

There are different types of visuomotor learning. Among the most studied is motor error-based learning where the sign and magnitude of the error are used to update motor commands. However, there are other instances where individuals show visuomotor learning even if the sign or magnitude of the error is precluded. Studies with patients suggest that the former learning is impaired after cerebellar lesions, while basal ganglia lesions disrupt the latter. Nevertheless, the cerebellar role is not restricted only to error-based learning, but it also contributes to several cognitive processes. Therefore, here, we tested if cerebellar ataxia patients are affected in two tasks, one that depends on error-based learning and the other that prevents the use of error-based learning. Our results showed that cerebellar patients have deficits in both visuomotor tasks; however, while error-based learning tasks deficits correlated with the motor impairments, the motor error-dependent task did not correlate with any motor measure.