Gluten Ataxia: an Underdiagnosed Condition

Immunotherapies for the Effective Treatment of Primary Autoimmune Cerebellar Ataxia: a Case Series

Primary autoimmune cerebellar ataxia (PACA) is an idiopathic sporadic cerebellar ataxia that is thought to be immune-mediated but lacks biomarkers or a known cause. Here, we report two cases of immune-mediated cerebellar ataxia that responded favorably to immunotherapy, in which tissue-based indirect immunofluorescence test for serum or cerebrospinal fluid (CSF) samples yielded positive results. Case 1 was a 78-year-old man who presented with subacute progressive gait ataxia with truncal instability and dysarthria in response to steroids. Case 2 was a 62-year-old man who presented with relapses and remissions of acute progressive cerebellar ataxia occurring 1-2 times per year. Despite a favorable response to steroid treatment, he relapsed repeatedly in the absence of long-term immunosuppression. In the case of "idiopathic" cerebellar ataxia, immune-mediated causes should be investigated, and immunotherapy may have therapeutic effects.

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.

Novelties in Autoimmune and Paraneoplastic Cerebellar Ataxias: Twenty Years of Progresses

Major advances in our knowledge concerning autoimmune and paraneoplastic cerebellar ataxias have occurred in the last 20 years. The discovery of several neural antibodies represents an undeniable contribution to this field, especially those serving as good biomarkers of paraneoplastic neurological syndromes and those showing direct pathogenic effects. Yet, many patients still lack detectable or known antibodies, and also many antibodies have only been reported in few patients, which makes it difficult to define in detail their clinical value. Nevertheless, a notable progress has additionally been made in the clinical characterization of patients with the main neural antibodies, which, although typically present with a subacute pancerebellar syndrome, may also show either hyperacute or chronic onsets that complicate the differential diagnoses. However, prodromal and transient features could be useful clues for an early recognition, and extracerebellar involvement may also be highly indicative of the associated antibody. Moreover, important advances in our understanding of the pathogenesis of cerebellar ataxias include the description of antibody effects, especially those targeting cell-surface antigens, and first attempts to isolate antigen-specific T-cells. Furthermore, genetic predisposition seems relevant, although differently involved according to cancer association, with particular HLA observed in non-paraneoplastic cases and genetic abnormalities in the tumor cells in paraneoplastic ones. Finally, immune checkpoint inhibitors used as cancer immunotherapy may rarely induce cerebellar ataxias, but even this undesirable effect may in turn serve to shed some light on their physiopathology. Herein, we review the principal novelties of the last 20 years regarding autoimmune and paraneoplastic cerebellar ataxias.