Cerebellar ataxia with sensory ganglionopathy; does autoimmunity have a role to play?

Can CANVAS due to RFC1 biallelic expansions present with pure ataxia?

BACKGROUND

Biallelic expansion of AAGGG in the replication factor complex subunit 1 (RFC1) was identified as a major cause of cerebellar ataxia, neuropathy (sensory ganglionopathy, or SG) and vestibular areflexia syndrome (CANVAS). We wanted to clarify if RFC1 expansions can present with pure ataxia and if such expansions could be responsible for some cases where an alternative diagnosis had been made.

METHODS

We identified patients with a combination of ataxia and SG and no other cause found, patients where an alternative diagnosis had been made, and patients with pure ataxia. Testing for RFC1 expansions was done using established methodology.

RESULTS

Among 54 patients with otherwise idiopathic sporadic ataxia without SG, none was found to have RFC1 expansions. Among 38 patients with cerebellar ataxia and SG in which all other causes were excluded, 71% had RFC1 expansions. Among 27 patients with cerebellar ataxia and SG diagnosed with coeliac disease or gluten sensitivity, 15% had RFC1 expansions.

CONCLUSIONS

Isolated cerebellar ataxia without SG makes the diagnosis of CANVAS due to RFC1 expansions highly improbable, but CANVAS is frequently the cause of the combination of idiopathic cerebellar ataxia with SG. It is important to screen patients diagnosed with other causes of acquired ataxia and SG as a small percentage were found to have RFC1 expansions.

Primary Sjögren syndrome-related peripheral neuropathy: A systematic review and meta-analysis

BACKGROUND AND PURPOSE

Primary Sjögren syndrome (pSS) is a chronic, systemic, autoimmune disorder characterized by lymphocytic infiltrates of the exocrine organs, leading to sicca symptoms and parotid enlargement. pSS has been linked to various neurological manifestations, including peripheral neuropathy (PN). We aimed to provide a comprehensive analysis of the currently available evidence regarding pSS-related PN.

METHODS

A literature search in the PubMed database was performed, and 49 papers were eligible to be included in this systematic review and meta-analysis.

RESULTS

The pooled prevalence of PN in pSS is estimated to be 15.0% (95% confidence interval = 10.7%-20.7%). The mean age of pSS patients at PN diagnosis is 59 years. Among the patients with pSS and PN, 83% are females. Neuropathic symptoms usually precede or lead to the pSS diagnosis at a 2:1 ratio in patients with pSS-related PN. The commonest type of pSS-related PN is distal axonal polyneuropathy (80% of patients with pSS-related PN), followed by sensory ganglionopathy. Peripheral and cranial mononeuropathies-particularly trigeminal-are also frequent. Risk factors for developing PN include increasing age and presence of vasculitis. Immune-mediated pathogenetic mechanisms are discussed. Glucocorticoids are the most commonly used treatment option for managing pSS-related PN, when associated with vasculitis, followed by the use of intravenous immunoglobulin.

CONCLUSIONS

PN is very common in pSS patients. Evidence on long-term prognosis of PN in pSS is limited, and further research is needed. Research into the use of immunosuppressive medication in nonvasculitic neuropathies in the context of pSS merits further consideration.

Primary Sjögren's syndrome (pSS)-related cerebellar ataxia: a systematic review and meta-analysis

BACKGROUND

Primary Sjögren's syndrome (pSS) is a chronic autoimmune disorder characterized by lymphocytic infiltrates of the exocrine glands, particularly the salivary and lacrimal glands, resulting in oral and ocular dryness. pSS has been linked to various neurological manifestations, including cerebellar dysfunction. We aimed to provide a comprehensive analysis of the currently available evidence regarding pSS-related cerebellar ataxia.

METHODS

A systematic literature search in the PubMed database was performed and 19 papers were eligible to be included in this paper.

RESULTS

The pooled prevalence of cerebellar ataxia in pSS is estimated to be 1.5% (95% CI 0.3-6.8%). pSS patients with cerebellar involvement have a female-to-male ratio of 6:1. Although most of the patients are adults in their fifth decade of life when diagnosed, cases of children with pSS and cerebellar involvement have been reported. Typical cerebellar ataxia related to pSS manifests with vermian dysfunction, namely gait ataxia and/or cerebellar speech. Cerebellar ataxia due to pSS may also mimic degenerative cerebellar ataxia, especially when the onset is progressive.

CONCLUSIONS

The diagnostic approach to a patient with cerebellar ataxia of unknown etiology should include evaluation for an underlying pSS. A thorough history and clinical examination, antibody testing, brain MRI imaging and/or MRS of the cerebellum will assist in establishing the diagnosis. Setting up a joint neuro-rheumatology clinic can be valuable given that rheumatic and neurological diseases share comorbidities.

The Intersection Between Cerebellar Ataxia and Neuropathy: a Proposed Classification and a Diagnostic Approach

Neuropathy is a common associated feature of different types of genetic or sporadic cerebellar ataxias. The pattern of peripheral nerve involvement and its associated clinical features can be an invaluable aspect for narrowing the etiologic diagnosis in the investigation of cerebellar ataxias. In this review, we discuss the differential diagnosis of the intersection between peripheral nerve and cerebellar involvement, and classify them in accordance with the predominant features. Genetics, clinical features, neuroimaging, and neurophysiologic characteristics are discussed. Furthermore, a diagnostic approach for cerebellar ataxia with neuropathy is proposed according to the different clinical characteristics. This is an Educational and Descriptive review with the aim of medical education for the approach to the patients with cerebellar ataxia and neuropathy. The diagnostic approach to the patient with cerebellar ataxia with neuropathy requires a detailed medical history, phenotyping, characterization of disease progression and family history. Neuroimaging features and the neurophysiological findings play pivotal roles in defining the diagnosis. Establishing an organized classification method for the disorders based on the clinical features may be very helpful, and could be divided as those with predominant cerebellar features, predominant neuropathic feature, or conditions with both cerebellar ataxia and neuropathy. Second, determining the mode of inheritance is critical on cerebellar ataxias: autosomal dominant and recessive cerebellar ataxias, mitochondrial or sporadic types. Third, one must carefully assess neurophysiologic findings in order to better characterize the predominant pattern of involvement: damage location, mechanism of lesion (axonal or demyelinating), motor, sensory or sensory motor compromise, large or small fibers, and autonomic system abnormalities.

Movement disorders in systemic autoimmune diseases: Clinical spectrum, ancillary investigations, pathophysiological considerations

With the advances in neuroimmunology especially due to the discovery of new neuronal antibodies, the recognition of treatable antibody-related movement disorders has recently received much attention. In contrast, the identification and characterisation of movement disorders associated with systemic autoimmune diseases remains a substantially unexplored area. Beyond the classic few associations such as chorea and antiphospholipid syndrome, or ataxia and coeliac disease, movement disorders have been reported in association with several systemic autoimmune diseases, however a clear image of clinical phenotypes, investigations, and treatment outcomes in these conditions has never been drawn. In this review, we analyse data from approximately 300 cases and summarise the epidemiological, clinical and diagnostic features of movement disorders associated with systemic autoimmune diseases, and the available knowledge about treatment and outcomes. We highlight that movement disorders in systemic autoimmune conditions are frequently the only or among a few presenting manifestations and are mostly treatable disorders responding to immunotherapy or dietary modifications. We point out the pertinent combination of clinical features and investigations which can suggest the underlying autoimmune nature of these movement disorders, and thus address the most appropriate treatment.

Neurological manifestation of coeliac disease with particular emphasis on gluten ataxia and immunological injury: a review article

Coeliac disease (CD) is a gluten-induced enteropathy affecting 1% of the population and has extra intestinal manifestations. One such expression involves nervous system, and CD may present as gluten ataxia (GA), peripheral neuropathy and epileptiform disorder among others. Considerable controversy exists on the exact pathophysiological mechanism of gluten leading to ataxia. It is, however, clear that in intestinal axis tissue transglutaminase 2 (tTG2) is the primary target but in the nervous system, tTG6 may be the causative antigen although its exact role is not clear. Furthermore, it has also been postulated that anti-gangliodise antibodies may play a role in the emergence of central pathology if not the key contender. Moreover, the association of neurological injury with non-coeliac gluten sensitivity (NCGS), a related but pathologically different condition implies an independent mechanism of neuronal injury by gluten in the absence of CD. This review will touch on the salient features of CD and the nervous system and will highlight current controversies in relation to gluten and GA.

Treatment of Neurological Manifestations of Gluten Sensitivity and Coeliac Disease

PURPOSE OF REVIEW

The aim of this paper was to overview the current literature in order to establish the available treatment options for the neurological manifestations of gluten-related disorders (serologically confirmed gluten sensitivity and coeliac disease).

RECENT FINDINGS

A range of debilitating neurological manifestations is increasingly being recognized in patients with gluten sensitivity with and without enteropathy even in the absence of gastrointestinal symptoms. Ataxia is the commonest neurological manifestation, followed by peripheral neuropathy. Epilepsy, headache, encephalopathy, various movement disorders, cognitive impairment, and muscle disorders have also been linked to gluten sensitivity and coeliac disease and are discussed in this review. Strict gluten-free diet is an effective first-line treatment of the neurological manifestations of gluten-related disorders. Very few patients will require additional immunosuppressive treatment usually in the form of mycophenolate.