[Usefulness of an anti-mouse cerebellar tissue-derived antigen antibody test in predicting immunotherapy efficacy in patients with idiopathic cerebellar ataxia].

BACKGROUND: Autoimmune cerebellar ataxia (AICA) is a general term for diseases in which the cerebellum is damaged by an autoimmune mechanism. For the diagnosis of the AICA, anti-thyroid antibodies (anti-thyroid peroxidase antibody and anti-thyroglobulin antibody), anti-glutamic acid decarboxylase (GAD) antibodies, and anti-gliadin antibodies are measured. Immunotherapy is known to be effective for AICA, but some patients with effective immunotherapy lack autoantibodies associated with cerebellar ataxia. The purpose of this study was to clarify whether the effectiveness of immunotherapy in patients with suspected AICA could be predicted by anti-mouse cerebellar tissue-derived antigen antibody tests. METHODS: This study was conducted on 25 patients with idiopathic cerebellar ataxia (excluding multiple system atrophy, hereditary spinocerebellar degeneration, cancer-bearing patients, and patients taking phenytoin) who received immunotherapy from 2005 to 2016 at Tokyo Medical University Hachioji Medical Center. The patients were suspected of having AICA because they were positive for cerebellar ataxia-related autoantibodies (anti-thyroid antibody, anti-GAD antibody, anti-gliadin antibody, or anti-transglutaminase 6 antibody) or other autoantibodies. Antibodies that bind to mouse cerebellar tissue-derived antigens were defined as "anti-mouse cerebellar tissue-derived antigen antibodies" in this study, and their IgG-class antibodies were comprehensively measured using a slot blot. RESULTS: Anti-mouse cerebellar tissue-derived antigen antibody test results were correlated with immunotherapy efficacy. Furthermore, the combination of anti-mouse cerebellar tissue-derived antigen and anti-GAD antibody tests could predict the effectiveness of immunotherapy with 83% sensitivity and 100% specificity, while the combination of the anti-mouse cerebellar tissue-derived antigen, anti-GAD, and anti-gliadin (IgA class) antibody tests could predict the effectiveness of immunotherapy with 94% sensitivity and 86% specificity. CONCLUSION: Anti-mouse cerebellar tissue-derived antigen antibody tests could help to provide useful information for immunotherapy administration to patients with idiopathic cerebellar ataxia suspected to be AICA.

[Cerebellar Ataxia and Autoantibodies].

The cerebellum is one of the main targets in the central nervous system for autoimmunity. Immune-mediated cerebellar ataxias include gluten ataxia, GAD antibody-associated cerebellar ataxia, Hashimoto's encephalopathy, and paraneoplastic cerebellar degeneration. Autoimmune cerebellar ataxia may be of either insidious or subacute onset, and vertigo or transient neurological symptoms occur in some patients before the onset of the disease, in contrast to spinocerebellar degeneration. If autoimmune cerebellar ataxia is suspected, early diagnosis and introduction of treatment are very important. For diagnosis, testing for gliadin antibody, TG6 antibody, GAD antibody, thyroid antibody, and anti-neuronal antibodies, including mGluR1, is useful. Magnetic resonance imaging voxel-based morphometry is also useful because it can detect cortical cerebellar atrophy of autoimmune cerebellar ataxia, different from spinocerebellar ataxia. As for treatment, it is important to remove autoimmune triggering factors (e.g.,dietary gluten or neoplasm). When the ataxia symptoms are causing hindrances in the daily life, it is worth considering immunotherapy including IVIg, steroid therapy and so on.

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: 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.

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.

[Autoantibodies associated with autoimmune-mediated cerebellar ataxia].

Various autoantibodies are associated with autoimmune-mediated cerebellar ataxia. Anti-Yo, -Zic, -CARPVIII, -Tr, -Ri, -Hu, -Ma, -CRMP-5, -ANNA-3, -PCA-2, -VGCC, and -mGluR antibodies (Abs) are found in paraneoplastic cerebellar ataxia, whereas anti-GAD, -thyroid, and -gliadin Abs are found in non-paraneoplastic cerebellar ataxia. Most of these antibodies are not pathogenic but are diagnostic markers. However, anti-VGCC, anti-mGluR, and anti-GAD Abs have been shown to cause cerebellar ataxia, because administration of these Abs mimics cerebellar ataxia in vivo. Experiments using in vitro preparations show that anti-VGCC Ab depresses excitatory synaptic transmissions, and anti-GAD Ab suppresses inhibitory synaptic transmissions. Anti-mGluR Ab interferes with the induction of synaptic plasticity. These results suggest that pathogenic Abs elicit cerebellar synaptic dysfunction, and thereby cause ataxia in patients.

Low-titer anti-GAD-antibody-positive cerebellar ataxia.

The majority of cases of anti-glutamic acid decarboxylase (GAD)-antibody-positive cerebellar ataxia are reported to have high levels of anti-GAD antibody, and the diagnostic value of low titers of anti-GAD antibody in a patient with cerebellar ataxia is still unknown. The purpose of this study was to verify the characteristics of low-titer-anti-GAD-antibody-positive cerebellar ataxia patients and the diagnostic value of low titers of anti-GAD antibody in patients with cerebellar ataxia. The subjects were six patients positive for low-titer GAD antibody (<100 U/mL). We examined them with MRI, including voxel-based morphometry, and with single-photon emission computed tomography and monitored the GAD antibody index in the cerebrospinal fluid. The levels of antineuronal, antigliadin, anti-SS-A, antithyroid antibodies, and of vitamins E, B1, and B12 were determined. Thoracic and abdominal CT scans were performed to exclude a paraneoplastic origin. We treated three patients with immunotherapy. All cases showed cortical cerebellar atrophy. The GAD antibody index in three of the five patients reviewed was >1.0. Two of the six patients were thyroid antibody-positive, and one was both antinuclear- and anti-SS-A antibody-positive. After the administration of immunotherapy to three patients, two showed clear effectiveness, and one, transient effectiveness. Effectiveness was greatest in the two patients with familial occurrence of the disease. In cerebellar ataxia, regardless of family history or isolated illness, it is critical to measure the GAD antibody level, and, even with a low titer level, if the result is positive, immunotherapy should be considered.

[A case of lung adenocarcinoma presenting with chorea with bilateral basal ganglial lesions on MRI].

The patient, a 63-year-old man, experienced the subacute onset of chorea, for which his family doctor prescribed oral haloperidol. However, the involuntary movements gradually worsened, and the patient was referred and admitted. High-signal lesions were seen in the caudate nucleus, putamen and globus pallidus bilaterally on MRI T2-weighted and FLAIR images. Chest CT, FDG-PET and tissue biopsies also revealed that the patient had lung adenocarcinoma with multiple lymph node metastases. The patient was diagnosed as having paraneoplastic chorea associated with primary lung adenocarcinoma. Antineuronal antibodies, such as anti-CRMP-5 and anti-Yo antibodies, were absent. The patient received steroid pulse therapy, oral prednisolone therapy, and concurrent radiochemotherapy. Chorea and high-signal lesions in the corpus striatum bilaterally on MRI improved quickly, and the mediastinal lymph node swelling also improved. The patient has been stable for 3 years since the onset of his symptoms. As the prognosis of paraneoplastic chorea is relatively favorable in some patients, it should be considered in the differential diagnosis of patients with chorea.

Intravenous immunoglobulin therapy for autoantibody-positive cerebellar ataxia.

OBJECTIVE: It has been reported that autoimmune cerebellar ataxias, such as anti-glutamic acid decarboxylase (GAD)-antibody-positive cerebellar ataxia and gluten ataxia, are treatable. Here, we examined the therapeutic efficacy of intravenous immunoglobulin (IVIg) on autoantibody-positive cerebellar ataxia. PATIENTS AND METHODS: IVIg therapy was administered in seven autoantibody-positive cerebellar ataxia patients. Therapeutic efficacy was examined in terms of its effects on clinical symptoms and changes in brain perfusion using single photon emission computed tomography (SPECT). RESULTS: Treatment was effective in four cerebellar cortical atrophy patients (two anti-GAD antibody-positive and two anti-gliadin antibody-positive) and in one anti-thyroid antibody-positive spinocerebellar ataxia type 3 (SCA3) patient, but not in two multiple system atrophy (MSA) patients. All four IVIg effective patients who underwent SPECT showed apparent increases in cerebellar perfusion. CONCLUSION: If cerebellar ataxia with an autoimmune mechanism is suspected and radiological findings do not reveal MSA, it is worth considering immunotherapy including IVIg.

[Efficacy of intravenous immunoglobulin for slowly progressive cerebellar atrophy].

In slowly progressive cerebellar atrophy, it has been difficult to suppress the progression of cerebellar symptoms because no effective therapeutic agents are available when the diagnosis of secondary cerebellar atrophy, such as drug-induced cerebellar atrophy or paraneoplastic syndrome, is denied. However, amongst the different forms of slowly progressive cerebellar atrophy, some may be associated with treatable immune abnormalities. Therefore, we investigated the therapeutic efficacy of intravenous immunoglobulin (IVIg) in 9 patients with slowly progressive cerebellar atrophy (4 sporadic atrophy; 5 hereditary atrophy). The results were as follows. With regard to the 4 cases of sporadic atrophy, gait ataxia and imbalance were markedly improved in 1 patient who had positive anti-GAD antibody. Moderate improvement was seen in 1 patient and slight improvement in 2. With regard to the 5 cases of hereditary atrophy, gait ataxia and imbalance were moderately improved in 2 patients with SCA3, although there were 3 non-responders. In conclusion, our study results suggested that not only patients with sporadic atrophy but also some with hereditary atrophy may respond to therapy. In cases of slowly progressive cerebellar atrophy in which the cause may be due to immune abnormality, we should consider instituting active immunotherapy when a pathological state caused by immune abnormality is suspected after extensive evaluations of autoantibodies, including anti-GAD, anti-thyroid and anti-gliadin antibody, malignancy, and so on.

Transthyretin Val 107 in a Japanese patient with familial amyloid polyneuropathy.

A 70-year-old Japanese man with amyloid polyneuropathy associated with a Val 107 transthyretin (TTR) mutation is reported. The patient presented with carpal tunnel syndrome, cardiomyopathy, bulbar palsy, dysphonia and polyneuropathy. DNA analysis of the TTR gene revealed a point mutation responsible for substitution of valine for isoleucine at position 107 of the TTR molecule. Taken together with reports of patients with the same TTR variant, Val 107 TTR mutation is probably associated with a clinical phenotype characterized by carpal tunnel syndrome, cardiomyopathy, bulbar palsy and dysphonia. This case implies a worldwide distribution of the Val 107 TTR mutation with a common clinical phenotype, despite different ethnic background.