Intravenous immunoglobulin therapy for autoantibody-positive cerebellar ataxia

Immunotherapy in a case of low titre GAD65 antibody-associated spectrum neurological disorders

We present a rare case of low titre GAD65 antibody-associated autoimmune encephalitis and status epilepticus in a young woman. She initially presented with left arm dystonic movements, contractures and status epilepticus. Due to the concern of autoimmune encephalitis and seizures, the patient received intravenous immunoglobulin empirically. After the detection of low serum GAD65 antibodies, the patient underwent immunomodulation therapy with significant improvement. This case demonstrated that in autoimmune encephalitis, it is important to monitor serum GAD65 antibodies levels and consider immunotherapy, despite mildly elevated serum levels. The patient's history of left arm dystonic movements without impaired awareness may have been due to limb dystonia, a presenting symptom of stiff person syndrome (SPS), despite SPS more commonly affecting axial muscles. This case further demonstrates that GAD65 antibody-related syndromes can manifest with different neurological phenotypes including co-occurrence of epilepsy with possible focal SPS despite low GAD65 antibodies titres.

Consensus Paper: Latent Autoimmune Cerebellar Ataxia (LACA)

Immune-mediated cerebellar ataxias (IMCAs) have diverse etiologies. Patients with IMCAs develop cerebellar symptoms, characterized mainly by gait ataxia, showing an acute or subacute clinical course. We present a novel concept of latent autoimmune cerebellar ataxia (LACA), analogous to latent autoimmune diabetes in adults (LADA). LADA is a slowly progressive form of autoimmune diabetes where patients are often initially diagnosed with type 2 diabetes. The sole biomarker (serum anti-GAD antibody) is not always present or can fluctuate. However, the disease progresses to pancreatic beta-cell failure and insulin dependency within about 5 years. Due to the unclear autoimmune profile, clinicians often struggle to reach an early diagnosis during the period when insulin production is not severely compromised. LACA is also characterized by a slowly progressive course, lack of obvious autoimmune background, and difficulties in reaching a diagnosis in the absence of clear markers for IMCAs. The authors discuss two aspects of LACA: (1) the not manifestly evident autoimmunity and (2) the prodromal stage of IMCA's characterized by a period of partial neuronal dysfunction where non-specific symptoms may occur. In order to achieve an early intervention and prevent cell death in the cerebellum, identification of the time-window before irreversible neuronal loss is critical. LACA occurs during this time-window when possible preservation of neural plasticity exists. Efforts should be devoted to the early identification of biological, neurophysiological, neuropsychological, morphological (brain morphometry), and multimodal biomarkers allowing early diagnosis and therapeutic intervention and to avoid irreversible neuronal loss.

Cerebellar Symptoms in Gluten Sensitivity: a Systematic Review of the Effect of a Gluten-Free Diet on Brain Imaging

Cerebellar manifestations have been described in patients with gluten sensitivity (GS)-related disorders. A better understanding of the neurological manifestations of GS requires the use of neuroimaging techniques. We performed a systematic review on neuroimaging findings in GS patients with cerebellar symptoms. We also included a specific search on neuroimaging findings in GS patients with cerebellar manifestations on a gluten-free diet (GFD). PubMed, Embase, and Bireme were systematically searched to identify studies assessing neuroimaging features of adults with cerebellar manifestations and GS with or without enteropathy on a GFD. Ten studies with a total of 222 adult-GS patients were included. Magnetic resonance imaging was used in 100% of the studies. Cerebellar atrophy was evaluated in 7 studies and observed in 63% of the patients. White matter abnormalities were described in 2 studies. Single-photon emission computed tomography was used in 2 studies, and decreased cerebellar perfusion was detected in 92% of the included patients. No study employed nuclear medicine after the start of GFD. Magnetic resonance spectroscopy (MRS) was performed in 2 studies before and after GFD. An increase in the Naa/Cr ratio in cerebellar vermis was seen in 98% of the cases on a strict GFD. Cerebellar atrophy was found to be a prevalent condition in GS patients. MRS demonstrated to be useful in the follow-up of GS patients with cerebellar manifestations on a GFD. Prospective studies using nuclear medicine imaging are needed to study brain changes in GS patients on a GFD.

Diagnosis and Clinical Features in Autoimmune-Mediated Movement Disorders

Movement disorders are common manifestations in autoimmune-mediated encephalitis. This group of diseases is suspected to be triggered by infection or neoplasm. Certain phenotypes correlate with specific autoantibody-related neurological disorders, such as orofacial-lingual dyskinesia with N-methyl-D-aspartate receptor encephalitis and faciobrachial dystonic seizures with leucine-rich glioma-inactivated protein 1 encephalitis. Early diagnosis and treatment, especially for autoantibodies targeting neuronal surface antigens, can improve prognosis. In contrast, the presence of autoantibodies against intracellular neuronal agents warrants screening for underlying malignancy. However, early clinical diagnosis is challenging because these diseases can be misdiagnosed. In this article, we review the distinctive clinical phenotypes, magnetic resonance imaging findings, and current treatment options for autoimmune-mediated encephalitis.

Advances in Therapies of Cerebellar Disorders: Immune-mediated Ataxias

The identification of an increasing number of immune mediated ataxias suggests that the cerebellum is often a target organ for autoimmune insults. The diagnosis of immune mediated ataxias is challenging as there is significant clinical overlap between immune mediated and other forms of ataxia. Furthermore the classification of immune mediated ataxias requires further clarification particularly for those ataxias where no specific antigenic trigger and associated antibodies have been identified. Recognition of immune mediated ataxias remains imperative as therapeutic interventions can be effective, although given the relative rarity of this entity, large-scale treatment trials may not be feasible. This review will discuss advances in therapies for immune mediated ataxias based on what is currently available in the literature.

Glutamic acid decarboxylase antibodies in neurocritical patients: a culprit or a bystander?

Background

Glutamic acid decarboxylase (GAD) is an intracellular enzyme, which is widely expressed in central nervous system (CNS), pancreas, and other organs. GAD antibodies (GAD-Abs) are linked to various neurological disorders. However, the significance of GAD-Abs in neurocritical patients is undetermined.

Materials and methods

Patients with serologically positive GAD-Abs and requiring neurocritical care were included. The clinical, laboratory, and outcome data were retrospectively collected.

Results

We included 9 patients with serologically positive GAD-Abs. Clinical manifestations involved both CNS and peripheral nervous system (PNS). Six (66.7%) patients had other specific autoimmune antibodies. Non-specific autoimmune responses were observed in 8 (88.9%) patients. All patients clinically responded well to immunotherapy. The titers of GAD-Abs decreased in 7 (77.8%) patients but remained unchanged in the other 2 patients. One (11.1%) patient awoke before the negative conversion of GAD-Abs, and 3 (33.3%) patients remained unconscious and/or under mechanical ventilation for several weeks after the vanishing of GAD-Abs.

Conclusions

Most neurocritical patients with serologically positive GAD-Abs had other specific autoimmune antibodies. All patients responded well to immunotherapy, but not parallel to the titers of GAD-Abs. These results indicated that GAD-Abs might be more a bystander than a culprit in neurocritical patients, suggesting that an underlying autoimmune disease should be explored.

Nonparaneoplastic autoimmune cerebellar ataxias

PURPOSE OF REVIEW

The current review develops the clinical presentations of nonparaneoplastic autoimmune cerebellar ataxia (ACA) and analyzes the association with autoantibodies.

RECENT FINDINGS

Emerging evidence suggests that autoimmunity is involved in a significant proportion of sporadic ataxia cases. Moreover, numerous autoantibodies have recently been described in association with sporadic cerebellar ataxia, improving diagnosis and patient categorization.

SUMMARY

Nonparaneoplastic ACA encompasses postinfectious acute cerebellar ataxia, opsoclonus-myoclonus-ataxia syndrome, and pure cerebellar ataxia with or without autoantibodies. There is still confusion about how to diagnose and classify the patients, and retrospective data suggest that these very rare entities are in fact largely underrecognized. Numerous autoantibodies have been found associated with sporadic ataxia, improving diagnosis accuracy, and patient categorization. However, although anti-glutamate decarboxylase isotype 65 (GAD65), anti-contactin-associated protein 2 (CASPR2), and anti metabotropic glutamate receptor (mGluR1) antibodies are well recognized biomarkers, many other autoantibodies have been described in very small numbers of patients and their specificity is unknown. Efficient biomarkers for ACA are still lacking and in many cases the diagnosis has to rely on a body of converging evidence.

Intravenous immunoglobulins in an adult case of post-EBV cerebellitis

Post-Epstein-Barr virus (EBV) cerebellitis is very rare complication of infectious mononucleosis and only a few adult cases are reported in literature. We present a 23-year-old patient who was admitted to the neurology service with worsening ataxia, nystagmus and dysarthria, 1 week after infectious mononucleosis. Imaging and cerebrospinal fluid studies were normal, serum studies revealed acute transaminitis and positive EBV viral capsid IgM and IgG. The patient underwent a 5-day course of intravenous immunoglobulins with rapid resolution of all his symptoms and was safely discharged home. The pathophysiology of post-EBV cerebellitis involves autoreactive antibodies, rather than a direct viral insult. Antineuronal antibodies might be the result of a mimicry between EBV proteins and neuronal antigens or they can be secreted by the EBV-transformed lymphocytes themselves. Many reports stress the benign, self-limiting nature of this syndrome; however, immunotherapy might de facto decrease the severity and duration of illness.

Physiological and Morphological Principles Underpinning Recruitment of the Cerebellar Reserve

Background:

In order to optimize outcomes of novel therapies for cerebellar ataxias (CAs), it is desirable to start these therapies while declined functions are restorable: i.e. while the so-called cere-bellar reserve remains.

Objective:

In this mini-review, we tried to define and discuss the cerebellar reserve from physiological and morphological points of view.

Method: The cerebellar neuron circuitry is designed to generate spatiotemporally organized outputs, re-gardless of the region. Therefore, the cerebellar reserve may be defined as a mechanism to restore its proper input-output organization of the cerebellar neuron circuitry, when it is damaged. Then, the follow-ing four components are essential for recruitment of the cerebellar reserve: operational local neuron cir-cuitry; proper combination of mossy fiber inputs to be integrated; climbing fiber inputs to instruct favor-able reorganization of the integration; deep cerebellar nuclei to generate reorganized outputs.

Results:

We discussed three topics related to these resources, 1) principles of generating organized cere-bellar outputs, 2) redundant mossy fiber inputs to the cerebellum, 3) plasticity of the cerebellar neuron circuitry.

Conclusion:

To make most of the cerebellar reserve, it is desirable to start any intervention as early as possible when the cerebellar cell loss is minimal or even negligible. Therefore, an ideal future therapy for degenerative cerebellar diseases should start before consuming the cerebellar reserve at all. In the meantime, our real challenge is to establish a reliable method to identify the decrease in the cerebellar re-serve as early as possible.

Neuroimaging Applications in Chronic Ataxias

Magnetic resonance imaging (MRI), single photon emission computed tomography (SPECT) and positron emission tomography (PET) are the main instruments for neuroimaging investigation of patients with chronic ataxia. MRI has a predominant diagnostic role in the single patient, based on the visual detection of three patterns of atrophy, namely, spinal atrophy, cortical cerebellar atrophy and olivopontocerebellar atrophy, which correlate with the aetiologies of inherited or sporadic ataxia. In fact spinal atrophy is observed in Friedreich ataxia, cortical cerebellar atrophy in Ataxia Telangectasia, gluten ataxia and Sporadic Adult Onset Ataxia and olivopontocerebellar atrophy in Multiple System Atrophy cerebellar type. The 39 types of dominantly inherited spinocerebellar ataxias show either cortical cerebellar atrophy or olivopontocerebellar atrophy. T2 or T2* weighted MR images can contribute to the diagnosis by revealing abnormally increased or decreased signal with a characteristic distribution. These include symmetric T2 hyperintensity of the posterior and lateral columns of the cervical spinal cord in Friedreich ataxia, diffuse and symmetric hyperintensity of the cerebellar cortex in Infantile Neuro-Axonal Dystrophy, symmetric hyperintensity of the peridentate white matter in Cerebrotendineous Xanthomatosis, and symmetric hyperintensity of the middle cerebellar peduncles and peridentate white matter, cerebral white matter and corpus callosum in Fragile X Tremor Ataxia Syndrome. Abnormally decreased T2 or T2* signal can be observed with a multifocal distribution in Ataxia Telangectasia and with a symmetric distribution in the basal ganglia in Multiple System Atrophy. T2 signal hypointensity lining diffusely the outer surfaces of the brainstem, cerebellum and cerebrum enables diagnosis of superficial siderosis of the central nervous system. The diagnostic role of nuclear medicine techniques is smaller. SPECT and PET show decreased uptake of radiotracers investigating the nigrostriatal system in Multiple System Atrophy and in patients with Fragile X Tremor Ataxia Syndrome. Semiquantitative or quantitative MRI, SPECT and PET data describing structural, microstructural and functional changes of the cerebellum, brainstem, and spinal cord have been widely applied to investigate physiopathological changes in patients with chronic ataxias. Moreover they can track diseases progression with a greater sensitivity than clinical scales. So far, a few small-size and single center studies employed neuroimaging techniques as surrogate markers of treatment effects in chronic ataxias.

Immune-mediated ataxias

Immune-mediated cerebellar ataxia (CA) comprises a group of rare diseases that are still incompletely described, and are probably underdiagnosed. Both acute and progressive progressions are possible. Different syndromes have been identified, including CA associated with anti-GAD antibodies, the cerebellar type of Hashimoto encephalopathy, primary autoimmune CA, gluten ataxia, opsoclonus-myoclonus syndrome, and paraneoplastic cerebellar degenerations. Most of these syndromes are associated with autoantibodies targeting neuronal antigens. Additionally, autoimmune CA can be triggered by infections, especially in children, and in rare cases occur in the context of an autoimmune multisystem disease, such as systemic lupus erythematosus, sarcoidosis, or Behçet disease. A careful workup is needed to distinguish autoimmune CA from other causes. In adults, a paraneoplastic origin must be ruled out, especially in cases with subacute onset. Neurologic outcome in adults is frequently poor, and optimal therapeutic strategies remain ill defined. The outcome in children is in general good, but children with a poor recovery are on record. The precise pathophysiologic mechanisms even in the presence of detectable autoantibodies are still largely unknown. Further research is needed on both the clinical and mechanistic aspects of immune-mediated CA, and to determine optimal therapeutic strategies.

Nuclear medicine of the cerebellum

Single-photon emission computed tomography (SPECT) and positron emission tomography (PET) with different radiotracers enable regional evaluation of blood flow and glucose metabolism, of receptors and transporters of several molecules, and of abnormal deposition of peptides and proteins in the brain. The cerebellum has been used as a reference region for different radiotracers in several disease conditions. Whole-brain voxel-wise analysis is not affected by a priori knowledge bias and should be preferred. SPECT and PET have contributed to establishing the cerebellum role in motion, cognition, and emotion control in physiologic and pathophysiologic conditions. The basic abnormal imaging findings include decreased or increased uptake of flow or metabolism tracers in the cerebellum alone or as part of a network. Decreased uptake is generally observed in primary structural damage of the cerebellum, but can also represent a distant effect of cerebral damage (crossed diaschisis). Increased uptake can be observed in Freidreich ataxia, inflammatory or immune-mediated diseases of the cerebellum, and in status epilepticus. The possibility is also recognized that primary structural damage of the cerebellum might determine distance effects on other brain structures (reversed diaschisis). So far, SPECT and PET have been predominantly used in clinical studies to investigate cerebellar changes in neurologic and psychiatric diseases and in connection with pharmacologic, transcranial magnetic stimulation, deep-brain stimulation, or surgical treatments.

Immune-mediated cerebellar ataxias: from bench to bedside

The cerebellum is a vulnerable target of autoimmunity in the CNS. The category of immune-mediated cerebellar ataxias (IMCAs) was recently established, and includes in particular paraneoplastic cerebellar degenerations (PCDs), gluten ataxia (GA) and anti-GAD65 antibody (Ab) associated-CA, all characterized by the presence of autoantibodies. The significance of onconeuronal autoantibodies remains uncertain in some cases. The pathogenic role of anti-GAD65Ab has been established both in vitro and in vivo, but a consensus has not been reached yet. Recent studies of anti-GAD65 Ab-associated CA have clarified that (1) autoantibodies are generally polyclonal and elicit pathogenic effects related to epitope specificity, and (2) the clinical course can be divided into two phases: a phase of functional disorder followed by cell death. These features provide the rationale for prompt diagnosis and therapeutic strategies. The concept “Time is brain” has been completely underestimated in the field of immune ataxias. We now put forward the concept “Time is cerebellum” to underline the importance of very early therapeutic strategies in order to prevent or stop the loss of neurons and synapses. The diagnosis of IMCAs should depend not only on Ab testing, but rather on a rapid and comprehensive assessment of the clinical/immune profile. Treatment should be applied during the period of preserved cerebellar reserve, and should encompass early removal of the conditions (such as remote primary tumors) or diseases that trigger the autoimmunity, followed by the combinations of various immunotherapies.

Cerebellar disease associated with anti-glutamic acid decarboxylase antibodies: review

Several neurological syndromes have been recognized associated to GAD antibodies. Among those disorders, cerebellar ataxia (CA) is one of the most common, along with stiff-person syndrome. Patients with GAD associated CA present with a progressive pancerebellar syndrome, with a subacute or chronic evolution, along with other neurological manifestations such as stiffness, oculomotor dysfunction, epilepsy, and cognitive dysfunction. These symptoms may be preceded by the so-called "brainstem attacks", where manifestations consistent with transient dysfunction of the brainstem may be observed. These patients frequently have extra-neurologic autoimmune manifestations such as diabetes mellitus type 1, polyendocrine autoimmune syndrome, pernicious anemia, vitiligo, etc. A proportion of patients may present with an underlying neoplasia, but the course is less aggressive than in those patients with classical paraneoplastic CA with onconeural antibodies. The diagnosis is based on the present of high serum and CSF titers of GAD antibodies, with intrathecal production of such antibodies. Treatment is aimed to decrease the immunological response with intravenous immunoglobulin, steroids, rituximab and oral immunosuppressive drugs. A subacute presentation and rapid initiation of immunotherapy seem to be the predictors of a favorable clinical response.

Low-Titre GAD Antibody-Associated Late-Onset Cerebellar Ataxia with a Significant Clinical Response to Intravenous Immunoglobulin Treatment

Antiglutamic acid decarboxylase antibody-associated cerebellar ataxia (GAD-Abs CA) is a rare, but increasingly detected, autoimmune neurological disorder characterized by the clinical presence of a cerebellar syndrome concomitant with positive GAD-Abs levels in serum and cerebrospinal fluid (CSF). It represents 3% of all immune-mediated sporadic CAs. Low-titre GAD-Abs CA is an even rarer subtype of GAD-Abs CA. We report on a 68-year-old woman with a 3-year history of progressive gait ataxia. In addition to the modified Rankin Scale (mRS), we used two other objective scales to evaluate CA severity, i.e. the International Cooperative Ataxia Rating Scale (ICARS) and the Scale for Assessment and Rating of Ataxia (SARA). Series of CT and MRI showed atrophy of the cerebellum. Except for the glycated haemoglobin (HbA_1c) levels, all other routine laboratory examinations were within normal limits. Autoimmune laboratory examinations showed positive (25.8 U/mL) serum GAD-Abs levels. The GAD antibody index was <1.0. The CSF analysis showed no oligoclonal immunoglobulin bands. Intravenous immunoglobulin (IVIg) therapy was started and significant improvement was observed. The diagnosis of low-titre GAD-Abs CA was established.

Clinical characteristics of patients with cerebellar ataxia associated with anti-GAD antibodies

ABSTRACT The enzyme glutamic acid decarboxylase (GAD), present in GABAergic neurons and in pancreatic beta cells, catalyzes the conversion of gamma-aminobutyric acid (GABA). The cerebellum is highly susceptible to immune-mediated mechanisms, with the potentially treatable autoimmune cerebellar ataxia associated with the GAD antibody (CA-GAD-ab) being a rare, albeit increasingly detected condition. Few cases of CA-GAD-ab have been described. Methods This retrospective and descriptive study evaluated the clinical characteristics and outcomes of patients with CA-GAD-ab. Result Three patients with cerebellar ataxia, high GAD-ab titers and autoimmune endocrine disease were identified. Patients 1 and 2 had classic stiff person syndrome and insidious-onset cerebellar ataxia, while Patient 3 had pure cerebellar ataxia with subacute onset. Patients received intravenous immunoglobulin therapy with no response in Patients 1 and 3 and partial recovery in Patient 2. Conclusion CA-GAD-ab is rare and its clinical presentation may hamper diagnosis. Clinicians should be able to recognize this potentially treatable autoimmune cerebellar ataxia.

Consensus Paper: Neuroimmune Mechanisms of Cerebellar Ataxias

In the last few years, a lot of publications suggested that disabling cerebellar ataxias may develop through immune-mediated mechanisms. In this consensus paper, we discuss the clinical features of the main described immune-mediated cerebellar ataxias and address their presumed pathogenesis. Immune-mediated cerebellar ataxias include cerebellar ataxia associated with anti-GAD antibodies, the cerebellar type of Hashimoto's encephalopathy, primary autoimmune cerebellar ataxia, gluten ataxia, Miller Fisher syndrome, ataxia associated with systemic lupus erythematosus, and paraneoplastic cerebellar degeneration. Humoral mechanisms, cell-mediated immunity, inflammation, and vascular injuries contribute to the cerebellar deficits in immune-mediated cerebellar ataxias.

Prevalence of Autoantibodies and the Efficacy of Immunotherapy for Autoimmune Cerebellar Ataxia

OBJECTIVE

Autoimmune cerebellar ataxias were recently reported to be treatable. However, the proportion of patients with cortical cerebellar atrophy of unknown etiology with autoimmune-associated cerebellar ataxia and the actual effectiveness of immunotherapy in these diseases remain unknown.

METHODS

We measured the level of autoantibodies (including anti-gliadin antibody, anti-glutamic acid decarboxylase (GAD) antibody, and anti-thyroid antibody) in 58 Japanese patients with cerebellar ataxia, excluding those with multiple system atrophy, hereditary spinocerebellar ataxia, cancer, or those who were receiving phenytoin, and the efficacy of immunotherapy was assessed.

RESULTS

Thirty-one of 58 (53%) patients were positive for anti-GAD antibody, anti-gliadin antibody, or anti-thyroid antibody. Seven of the 12 anti-gliadin antibody-positive patients, three of the four anti-GAD antibody-positive patients, and three of the six anti-thyroid antibody-positive patients responded well to immunotherapy, indicating that 59% of patients with ataxia-associated antibody-positive cerebellar ataxia undergoing immunotherapy responded well.

CONCLUSION

Some patients with cerebellar ataxia have autoimmune conditions and diagnosing autoimmune cerebellar ataxia is therefore an important component in the care of patients with this disease entity.

Consensus paper: radiological biomarkers of cerebellar diseases

Hereditary and sporadic cerebellar ataxias represent a vast and still growing group of diseases whose diagnosis and differentiation cannot only rely on clinical evaluation. Brain imaging including magnetic resonance (MR) and nuclear medicine techniques allows for characterization of structural and functional abnormalities underlying symptomatic ataxias. These methods thus constitute a potential source of radiological biomarkers, which could be used to identify these diseases and differentiate subgroups of them, and to assess their severity and their evolution. Such biomarkers mainly comprise qualitative and quantitative data obtained from MR including proton spectroscopy, diffusion imaging, tractography, voxel-based morphometry, functional imaging during task execution or in a resting state, and from SPETC and PET with several radiotracers. In the current article, we aim to illustrate briefly some applications of these neuroimaging tools to evaluation of cerebellar disorders such as inherited cerebellar ataxia, fetal developmental malformations, and immune-mediated cerebellar diseases and of neurodegenerative or early-developing diseases, such as dementia and autism in which cerebellar involvement is an emerging feature. Although these radiological biomarkers appear promising and helpful to better understand ataxia-related anatomical and physiological impairments, to date, very few of them have turned out to be specific for a given ataxia with atrophy of the cerebellar system being the main and the most usual alteration being observed. Consequently, much remains to be done to establish sensitivity, specificity, and reproducibility of available MR and nuclear medicine features as diagnostic, progression and surrogate biomarkers in clinical routine.

Guidelines for treatment of immune-mediated cerebellar ataxias

Immune-mediated cerebellar ataxias include gluten ataxia, paraneoplastic cerebellar degeneration, GAD antibody associated cerebellar ataxia, and Hashimoto’s encephalopathy. Despite the identification of an increasing number of immune-mediated cerebellar ataxias, there is no proposed standardized therapy. We evaluated the efficacies of immunotherapies in reported cases using a common scale of daily activity. The analysis highlighted the importance of removal of autoimmune triggering factors (e.g., gluten or cancer) and the need for immunotherapy evaluation (e.g., corticosteroids, intravenous immunoglobulin, immunosuppressants) and adaptation according to each subtype.

Ataxia

Ataxia is a disorder of balance and coordination resulted from dysfunctions involving cerebellum and its afferent and efferent connections. While a variety of disorders can cause secondary ataxias, the list of genetic causes of ataxias is growing longer. Genetic abnormalities may involve mitochondrial dysfunction, oxidative stress, abnormal mechanisms of DNA repair, possible protein misfolding, and abnormalities in cytoskeletal proteins. Few ataxias are fully treatable while hope for efficacious gene therapy and pharmacotherapy is emerging. A discussion of the ataxias is presented here with brief mention of acquired ataxias, and a greater focus on inherited ataxias.

Gluten ataxia in Japan

Gluten ataxia, a type of cerebellar ataxia caused by exposure to gluten in sensitive patients, has been considered common in the USA and Europe, and rare in Asia. We measured anti-deamidated gliadin peptide (DGP) antibody levels in 49 patients with cerebellar ataxia, excluding those with multiple system atrophy, hereditary spinocerebellar ataxia, or cancer, as well as those who were receiving oral administration of phenytoin. Anti-DGP antibody was positive in eight (16.3 %) patients, five of these patients were positive only for IgA, one was positive for both IgG and IgA, and two were positive only for IgG antibody. Intravenous immunoglobulin was administered to five of the eight patients, and was markedly effective in one, moderately effective in two, and ineffective in two. Steroid therapy was administered to four patients, but none had an apparent response. Ataxia symptoms improved in one patient treated with a gluten-free diet only. Although it had been thought to be extremely rare in Asia, we speculate that more than 10 % of cerebellar ataxia patients in Japan currently have gluten ataxia; therefore, measuring anti-DGP antibody or anti-gliadin antibody in cerebellar ataxia patients in Asia is important.

Cerebellar ataxia and glutamic acid decarboxylase antibodies: immunologic profile and long-term effect of immunotherapy

IMPORTANCE

Current clinical and immunologic knowledge on cerebellar ataxia (CA) with glutamic acid decarboxylase 65 antibodies (GAD65-Abs) is based on case reports and small series with short-term follow-up data.

OBJECTIVE

To report the symptoms, additional antibodies, prognostic factors, and long-term outcomes in a cohort of patients with CA and GAD65-Abs.

DESIGN, SETTING, AND PARTICIPANTS

Retrospective cohort study and laboratory investigations at a center for autoimmune neurologic disorders among 34 patients with CA and GAD65-Abs, including 25 with long-term follow-up data (median, 5.4 years; interquartile range, 3.1-10.3 years).

MAIN OUTCOMES AND MEASURES

Analysis of clinicoimmunologic features and predictors of response to immunotherapy. Immunochemistry on rat brain, cultured neurons, and human embryonic kidney cells expressing GAD65, GAD67, α1-subunit of the glycine receptor, and a repertoire of known cell surface autoantigens were used to identify additional antibodies. Twenty-eight patients with stiff person syndrome and GAD65-Abs served as controls.

RESULTS

The median age of patients was 58 years (range, 33-80 years); 28 of 34 patients (82%) were women. Nine patients (26%) reported episodes of brainstem and cerebellar dysfunction or persistent vertigo several months before developing CA. The clinical presentation was subacute during a period of weeks in 13 patients (38%). Nine patients (26%) had coexisting stiff person syndrome symptoms. Systemic organ-specific autoimmunities (type 1 diabetes mellitus and others) were present in 29 patients (85%). Twenty of 25 patients with long-term follow-up data received immunotherapy (intravenous immunoglobulin in 10 and corticosteroids and intravenous immunoglobulin or other immunosuppressors in 10), and 7 of them (35%) improved. Predictors of clinical response included subacute onset of CA (odds ratio [OR], 0.50; 95% CI, 0.25-0.99; P = .047) and prompt immunotherapy (OR, 0.98; 95% CI, 0.96-0.99; P = .01). Similar frequencies of serum GAD67-Abs were found in patients with CA (24 of 34 patients [71%]) and in patients with stiff person syndrome (20 of 28 patients [71%]). However, GAD67-Abs were found in all of the cerebrospinal fluid samples examined (22 samples from patients with CA and 17 samples from patients with stiff person syndrome). Glycine receptor antibodies but not other cell surface antibodies were identified in 4 patients with CA. The presence of glycine receptor antibodies did not correlate with any specific clinical feature.

CONCLUSIONS AND RELEVANCE

In patients with CA and GAD65-Abs, subacute onset of symptoms and prompt immunotherapy are associated with good outcome. Persistent vertigo or brainstem and cerebellar episodes can herald CA and should lead to GAD65-Ab testing, particularly in patients with systemic organ-specific autoimmunities.

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.

Elevated titers of anti-thyroperoxidase antibodies in patients with multiple system atrophy: a pilot study

OBJECTIVES

Multiple system atrophy (MSA) is a neurodegenerative disease characterized by progressive neuronal loss and alpha-synuclein deposition in oligodendroglial cells in the central nervous system. The cause of MSA remains essentially unknown. A cerebellar syndrome was associated with autoimmune thyroid disease in some cases, apparently not related to MSA and was partially responsive to immunomodulatory therapy.

PATIENTS AND METHODS

28 euthyroid patients who fulfilled the diagnostic criteria for probable MSA, 11 with MSA-cerebellar type (MSA-C), 17 with MSA-parkinsonian type (MSA-P), 28 patients with Parkinson's disease (PD) and 26 normal euthyroid controls were tested the for serum levels of anti-thyroperoxidase antibodies (anti-TPO) and anti-thyroglobulin (Anti-TG) antibodies (Ab).

RESULTS

The laboratory results were statistically similar in all three groups, but 3 MSA-C patients had highly elevated anti-TPO Ab titers.

CONCLUSION

We identified the presence of elevated anti-TPO levels in a small subgroup of MSA-C patients but neither in MSA-P or PD patients nor in healthy controls. These findings may suggest an autoimmune etiology in some cases of MSA-C.

Effects of intravenous immunoglobulin on alpha synuclein aggregation and neurotoxicity

α-Synuclein is thought to contribute to the pathogenesis of Parkinson's disease (PD). It is the main protein in Lewy bodies, the pathognomonic inclusion bodies in the PD substantia nigra, and mutations which increase its aggregation and/or expression are associated with familial early-onset parkinsonism. Soluble oligomers are considered to be α-synuclein's most neurotoxic conformation. We previously reported that intravenous immunoglobulin (IVIG) products contain specific antibodies to α-synuclein which do not prevent development of four-day α-synuclein oligomers. The objective of this study was to further examine IVIG's effects on α-synuclein's aggregation and neurotoxicity. The IVIG product Gammagard (Baxter Healthcare) did not prevent the development of nine-day α-synuclein oligomers, nor did it degrade preformed oligomers, as shown by western blots performed on gels run under reducing/denaturing conditions and native gels. In western blots of native gels, an additional low molecular weight band (~22 kDa) was detected in α-synuclein incubated for four days in Gammagard, but not in Gammagard alone. No significant differences were found for Thioflavin-T reactivity between α-synuclein amorphous aggregates grown in Gammagard vs. those grown in phosphate-buffered saline. Gammagard partially protected SK-N-BE(2)M17 human neuroblastoma cells against α-synuclein oligomer toxicity (p = 0.007 vs. protective effects of normal human IgG). These findings suggest that although IVIG does not prevent α-synuclein aggregation, it still may reduce α-synuclein neurotoxicity through an unknown mechanism.

Magnetic resonance and nuclear medicine imaging in ataxias

Imaging techniques including computed tomography (CT), magnetic resonance imaging (MRI), single photon emission computed tomography (SPECT), and positron emission tomography (PET) have been widely applied to the investigation of patients with acute or chronic ataxias. Fundamentally, CT has a role in the emergency evaluation of the patient with acute ataxia to ascertain brainstem or cerebellar hemorrhage and to exclude a mass lesion in the posterior cranial fossa. Conventional MRI is the most frequently performed imaging investigation in patients with ataxia. It can support the diagnosis of acute cerebellitis and Wernicke encephalopathy by revealing T2 signal changes with a typical distribution. In patients with inherited or sporadic chronic ataxia it reveals three fundamental patterns of atrophy of the brainstem, cerebellum, and spinal cord which match the gross neuropathological descriptions. These are represented by olivopontocerebellar atrophy (OPCA), cortical cerebellar atrophy (CCA), and spinal atrophy (SA). A substantial correspondence exists among these patterns of atrophy shown by MRI and the etiological classification of inherited or acquired chronic ataxias. This, along with demonstration of T2 signal changes characteristic of some diseases, makes conventional MRI potentially useful for the diagnostic work-up of the single patient, especially in the case of a sporadic disease. Non-conventional MR techniques including diffusion MR, spectroscopy, and functional MR have been used in patients with acute or chronic ataxia, but their exact role in the evaluation of the single patient is not established yet. They are currently investigated as potential tools to monitor progression of neurodegeneration in chronic ataxia and to serve as "surrogate markers" in clinical trials. Several radiotracers have been utilized in combination with SPECT and PET in patients with ataxia. Perfusion SPECT can reveal cerebellar blood flow abnormalities early in the course of cerebellitis. It has also been utilized to investigate perfusion of the brain in several inherited or sporadic chronic ataxic diseases, contributing to improved understanding of the pathophysiology of these conditions. Recently, perfusion SPECT has been tested as a "surrogate marker" to verify the effects of newly developed therapies in patients with a variety of chronic ataxias. Whole-body FDG-PET is recommended in patients with suspected paraneoplastic cerebellar degeneration to detect the primary malignancy. Brain FDG-PET has provided important information on the pathophysiology of several acquired and inherited conditions. PET and SPECT with radiotracers able to assess the nigrostriatal system or the density of D2 dopamine receptors in the striatum are increasingly used in patients with adult-onset sporadic ataxia for the differential diagnosis between multiple system atrophy in which overt striatal abnormalities are found and idiopathic late-onset cerebellar ataxia in which no abnormality is detected.

[Case of anti-TPO/gliadin antibody-positive cerebellar atrophy that responded to intravenous immunoglobulin therapy begun 16 years after onset]

We present a case of slowly progressive gait ataxia with a 16-year history in an 87-year-old woman. In 1994 she became aware of a slight unsteadiness while walking and cortical cerebellar atrophy was diagnosed. She had no familial history of neurological disorders. In 2007, idiopathic thrombocytopenic purpura (ITP) was diagnosed. The symptoms gradually worsened, and she was admitted in 2010 because she could not walk without support. MRI voxel-based morphometry (VBM) imaging showed atrophy of the entire cerebellum, and SPECT using eZIS showed reduced perfusion in the same regions. Her blood was positive for both anti-TPO antibody (42 IU/ml) and anti-gliadin antibody (20.2 EU). We therefore diagnosed autoimmune cerebellar atrophy. The patient showed a positive response to intravenous immunoglobulins (IVIg) and regained the ability to walk unassisted. Her posture and gait disturbance scores on the International Cooperative Ataxia Rating Scale had improved from 20 to 9. Even 16 years after onset, intravenous immunoglobulins were effective. In cases of prolonged disease, immunotherapy can be effective in autoimmune cerebellar atrophy and should not be excluded from the treatment choices.

Machado-Joseph disease and other rare spinocerebellar ataxias

The spinocerebellar ataxias (SCAs) are a group of neurodegenerative diseases characterised by progressive lack of motor coordination leading to major disability. SCAs show high clinical, genetic, molecular and epidemiological variability. In the last one decade, the intensive scientific research devoted to the SCAs is resulting in clear advances and a better understanding on the genetic and nongenetic factors contributing to their pathogenesis which are facilitating the diagnosis, prognosis and development of new therapies. The scope of this chapter is to provide an updated information on Machado-Joseph disease (MJD), the most frequent SCA subtype worldwide and other rare spinocerebellar ataxias including dentatorubral-pallidoluysian atrophy (DRPLA), the X-linked fragile X tremor and ataxia syndrome (FXTAS) and the nonprogressive episodic forms of inherited ataxias (EAs). Furthermore, the different therapeutic strategies that are currently being investigated to treat the ataxia and non-ataxia symptoms in SCAs are also described.

Multiple system atrophy: current and future approaches to management

Multiple system atrophy (MSA) is a rare neurodegenerative disorder without any effective treatment in slowing or stopping disease progression. It is characterized by poor levodopa responsive Parkinsonism, cerebellar ataxia, pyramidal signs and autonomic failure in any combination. Current therapeutic strategies are primarily based on dopamine replacement and improvement of autonomic failure. However, symptomatic management remains disappointing and no curative treatment is yet available. Recent experimental evidence has confirmed the key role of alpha-synuclein aggregation in the pathogenesis of MSA. Referring to this hypothesis, transgenic and toxic animal models have been developed to assess candidate drugs for MSA. The standardization of diagnosis criteria and assessment procedures will allow large multicentre clinical trials to be conducted. In this article we review the available symptomatic treatment, recent results of studies investigating potential neuroprotective drugs, and future approaches for the management in MSA.

Selective loss of Purkinje cells in a patient with anti-gliadin-antibody-positive autoimmune cerebellar ataxia

The patient was an 84-year-old woman who had the onset of truncal ataxia at age 77 and a history of Basedow's disease. Her ataxic gait gradually deteriorated. She could not walk without support at age 81 and she was admitted to our hospital at age 83. Gaze-evoked nystagmus and dysarthria were observed. Mild ataxia was observed in all limbs. Her deep tendon reflex and sense of position were normal. IgA anti-gliadin antibody, IgG anti-gliadin antibody, anti-SS-A/Ro antibody, anti-SS-B/La antibody and anti-TPO antibody were positive. A conventional brain MRI did not show obvious cerebellar atrophy. However, MRI voxel based morphometry (VBM) and SPECT-eZIS revealed cortical cerebellar atrophy and reduced cerebellar blood flow. IVIg treatment was performed and was moderately effective. After her death at age 85, the patient was autopsied. Neuropathological findings were as follows: selective loss of Purkinje cells; no apparent degenerative change in the efferent pathways, such as the dentate nuclei or vestibular nuclei; no prominent inflammatory reaction. From these findings, we diagnosed this case as autoimmune cerebellar atrophy associated with gluten ataxia. All 3 autopsies previously reported on gluten ataxia have noted infiltration of inflammatory cells in the cerebellum.

In this case, we postulated that the infiltration of inflammatory cells was not found because the patient's condition was based on humoral immunity. The clinical conditions of gluten ataxia have not yet been properly elucidated, but are expected to be revealed as the number of autopsied cases increases.

Specific antibodies to soluble alpha-synuclein conformations in intravenous immunoglobulin preparations

Alpha-synuclein is the major protein in Lewy bodies, the hallmark pathological finding in Parkinson's disease (PD) and dementia with Lewy bodies (DLB). Although normally intracellular, it also can be secreted, so extracellular alpha-synuclein may contribute to neuronal injury. Serum antibodies to alpha-synuclein could exert protective effects by increasing alpha-synuclein's movement out of the brain and, if they cross the blood-brain barrier, by inhibiting its neurotoxic effects. The objective of this study was to measure antibody concentrations to alpha-synuclein monomer and soluble oligomers in three intravenous immunoglobulin (IVIG) preparations, Gamunex (Talecris Biotherapeutics), Gammagard (Baxter Healthcare) and Flebogamma (Grifols Biologicals). Antibodies were measured in native IVIG preparations and after antibody-antigen complex dissociation. IVIG's non-specific binding was subtracted from its total binding to alpha-synuclein to calculate specific anti-alpha-synuclein antibody concentrations. Specific antibodies to alpha-synuclein monomer and/or soluble oligomers were detected in all IVIG products. In native IVIG preparations, the highest anti-monomer concentrations were in Gammagard and the highest anti-oligomer concentrations were in Gamunex; the extent to which lot-to-lot variation may have contributed to these differences was not determined. Antibody-antigen complex dissociation had variable effects on these antibody levels. The IVIG preparations did not inhibit alpha-synuclein oligomer formation, although they changed the distribution and intensity of some oligomer bands on Western blots. The presence of antibodies to soluble alpha-synuclein conformations in IVIG preparations suggests that their effects should be studied in animal models of synucleinopathies, as a first step to determine their feasibility as a possible treatment for PD and other synucleinopathies.

Anti transglutaminase antibodies cause ataxia in mice

Background

Celiac disease (CD) is an autoimmune gastrointestinal disorder characterized by the presence of anti-transglutaminase 2 (TG2) and anti-gliadin antibodies. Amongst the neurological dysfunctions associated with CD, ataxia represents the most common one.

Methods

We analyzed by immunohistochemistry, the anti-neural reactivity of the serum from 20 CD patients. To determine the role of anti-TG2 antibodies in ataxia, two anti-TG2 single chain variable fragments (scFv), isolated from a phage-display IgA antibody library, were characterized by immunohistochemistry and ELISA, and injected in mice to study their effects on motor coordination. We found that 75% of the CD patient population without evidence of neurological involvement, has circulating anti-neural IgA and/or IgG antibodies. Two anti-TG2 scFvs, cloned from one CD patient, stained blood vessels but only one reacted with neurons. This anti-TG2 antibody showed cross reactivity with the transglutaminase isozymes TG3 and TG6. Intraventricular injection of the anti-TG2 or the anti-TG2/3/6 cross-reactive scFv provoked transient, equally intensive ataxia in mice.

Conclusion

The serum from CD patients contains anti-TG2, TG3 and TG6 antibodies that may potentially cause ataxia.

Neurologic presentations of gastrointestinal disease

In recent years, there has been increasing recognition of the presence of gastrointestinal (GI) dysfunction in the setting of neurologic diseases. Parkinson's disease is a particularly well-known example, but GI dysfunction also may occur in multiple sclerosis, stroke, and in various myopathic and peripheral neuropathic processes. There is much less awareness, however, that primary GI diseases may also display neurologic dysfunction as part of their clinical picture. This article focuses on some of those disease processes. Illnesses primarily targeting the GI tract are addressed and examples of primary esophageal, gastric, and intestinal disease processes are described.

Classification of cerebellar atrophy using voxel-based morphometry and SPECT with an easy Z-score imaging system

OBJECTIVE

With conventional MRI and single-photon emission computed tomography (SPECT), accurate diagnosis and precise classification of cerebellar atrophy are often difficult. The objective was to verify the utility of MRI voxel-based morphometry (VBM) in combination with SPECT using easy Z-score imaging (eZIS) for diagnosing and classifying cerebellar atrophy.

PATIENTS AND METHODS

We assessed gray matter atrophy using VBM and blood perfusion using SPECT with eZIS in fifteen patients with different types of cerebellar atrophy, such as the cerebellar variant of multiple system atrophy (MSA-C), spinocerebellar ataxia type 3 (SCA3), SCA6, and autoimmune cerebellar ataxia (AICA).

RESULTS

In all five MSA-C patients, VBM imaging showed atrophy of the brainstem, the entire cerebellar vermis, and the cerebellar hemispheres, while SPECT using eZIS showed reduced perfusion in the same regions. Regarding SCA3, brainstem atrophy and reduced perfusion were recognized in two of the four patients, but none exhibited abnormal findings in the posterior lobe of the cerebellar vermis. SPECT showed that all four patients had obviously reduced perfusion in the anterior lobe of the vermis, but VBM demonstrated that there was no obvious atrophy of gray matter in any patient, meaning that the results of SPECT and VBM contradicted each other completely. All SCA6 and AICA patients exhibited atrophy and reduced perfusion in the cerebellar hemispheres but not in the brainstem. Only one AICA patient exhibited atrophy and reduced perfusion of the entire cerebellar vermis.

CONCLUSION

VBM clearly showed characteristic gray matter atrophy in the cerebellum and brainstem in different pathological conditions, thus indicating its high degree of utility in diagnosing and classifying cerebellar atrophy in combination with SPECT using eZIS.

Animal models of human cerebellar ataxias: a cornerstone for the therapies of the twenty-first century

Cerebellar ataxias represent a group of disabling neurological disorders. Our understanding of the pathogenesis of cerebellar ataxias is continuously expanding. A considerable number of laboratory animals with neurological mutations have been reported and numerous relevant animal models mimicking the phenotype of cerebellar ataxias are becoming available. These models greatly help dissecting the numerous mechanisms of cerebellar dysfunction, a major step for the assessment of therapeutics targeting a given deleterious pathway and for the screening of old or newly synthesized chemical compounds. Nevertheless, differences between animal models and human disorders should not be overlooked and difficulties in terms of characterization should not be occulted. The identification of the mutations of many hereditary ataxias, the development of valuable animal models, and the recent identifications of the molecular mechanisms underlying cerebellar disorders represent a combination of key factors for the development of anti-ataxic innovative therapies. It is anticipated that the twenty-first century will be the century of effective therapies in the field of cerebellar ataxias. The animal models are a cornerstone to reach this goal.