Immune-mediated cerebellar ataxias (IMCAs) represent a group of disorders in which the immune system targets mainly the cerebellum and related structures. We address fundamental questions on the diagnosis and immunological pathogenesis of IMCAs, as illuminated by recent advances in the field. Various types of IMCAs have been identified, including post-infectious cerebellitis, Miller Fisher syndrome, gluten ataxia, paraneoplastic cerebellar degeneration (PCD), opsoclonus and myoclonus syndrome, and anti-GAD ataxia. In some cases, identification of several well-characterized autoantibodies points to a specific etiology in IMCAs and leads to a firm diagnosis. In other cases, various autoantibodies have been reported, but their interpretation requires a careful consideration. Indeed, some autoantibodies have only been documented in a limited number of cases and the causal relationship is not established. In order to facilitate an early treatment and prevent irreversible lesions, new entities have been defined in recent years, such as primary autoimmune cerebellar ataxia (PACA) and latent autoimmune cerebellar ataxia (LACA). PACA is characterized by autoimmune features which do not align with traditional etiologies, while LACA corresponds to a prodromal stage. LACA does not imply the initiation of an immunotherapy but requires a close follow-up. Concurrently, accumulation of clinical data has led to intriguing hypotheses regarding the mechanisms of autoimmunity, such as a pathogenesis of autoimmunity against synapses (synaptopathies), and the vulnerability of the entire nervous system when the immunity targets ion channels and astrocytes. The development of PCD in patients treated with immune-checkpoint inhibitors suggests that molecular mimicry specifically determines the direction of autoimmunity, and that the strength of this response is modulated by co-signaling molecules that either enhance or dampen signals from the antigen-specific T cell receptor.

暂无摘要。

Guillain-Barré syndrome/Miller-Fisher syndrome (GBS/MFS) overlap syndrome is an extremely rare variant of Guillain-Barré syndrome (GBS) in which Miller-Fisher syndrome (MFS) coexists with other characteristics of GBS, such as limb weakness, paresthesia, and facial paralysis. We report the clinical case of a 12-year-old patient, with no pathological history, who acutely presents with ophthalmoplegia, areflexia, facial diplegia, and swallowing and phonation disorders, followed by progressive, descending, and symmetrical paresis affecting first the upper limbs and then the lower limbs. An albuminocytological dissociation was found in the cerebrospinal fluid study. Magnetic resonance imaging of the spinal cord showed enhancement and thickening of the cauda equina roots. The patient was treated with immunoglobulins with a favorable clinical outcome.

BACKGROUND: Miller-Fisher syndrome (MFS) is a rare subtype of Guillain-Barre syndrome with classic features of ataxia, areflexia, and ophthalmoplegia that can be caused by a preceding infection including COVID-19. We present a current, asymptomatic thrombocytopenic COVID-19 infection as a cause of MFS in a 60-year-old male with a concurrent chronic immune neuropathy.
METHODS: A 60-year-old male presenting with acute symptoms of MFS including ataxia, areflexia, and ophthalmoplegia on a chronic immune neuropathy for at least 1 year and concurrent asymptomatic COVID-19 positive infection.
METHODS: MFS suspected secondary to a current thrombocytopenic COVID-19 infection.
METHODS: Five days of intravenous immune globulin with continued monthly intravenous immune globulin as an outpatient, follow-up long-term in a neuromuscular clinic, electromyography as an outpatient, and continued physical therapy.
RESULTS: The patient significantly improved after initial treatment.
CONCLUSIONS: The full effect of COVID-19 on the various Guillain-Barre syndrome subtypes is unknown, although it clearly can be a cause of the various variants including being caused by a current, asymptomatic infection.

OBJECTIVE: In this retrospective study, we aimed at defining the clinical, paraclinical and outcome features of acute neurological syndromes associated with anti-GQ1b antibodies.
RESULTS: We identified 166 patients with neurological symptoms appearing in less than 1 month and anti-GQ1b antibodies in serum between 2012 and 2022. Half were female (51%), mean age was 50 years (4-90), and the most frequent clinical features were areflexia (80% of patients), distal upper and lower limbs sensory symptoms (78%), ophthalmoplegia (68%), sensory ataxia (67%), limb muscle weakness (45%) and bulbar weakness (45%). Fifty-three patients (32%) presented with complete (21%) and incomplete (11%) Miller Fisher syndrome (MFS), thirty-six (22%) with Guillain-Barre syndrome (GBS), one (0.6%) with Bickerstaff encephalitis (BE), and seventy-three (44%) with mixed MFS, GBS & BE clinical features. Nerve conduction studies were normal in 46% of cases, showed demyelination in 28%, and axonal loss in 23%. Anti-GT1a antibodies were found in 56% of cases, increased cerebrospinal fluid protein content in 24%, and Campylobacter jejuni infection in 7%. Most patients (83%) were treated with intravenous immunoglobulins, and neurological recovery was complete in 69% of cases at 1 year follow-up. One patient died, and 15% of patients relapsed. Age > 70 years, initial Intensive Care Unit (ICU) admission, and absent anti-GQ1b IgG antibodies were predictors of incomplete recovery at 12 months. No predictors of relapse were identified.
CONCLUSIONS: This study from Western Europe shows acute anti-GQ1b antibody syndrome presents with a large clinical phenotype, a good outcome in 2/3 of cases, and frequent relapses.

暂无摘要。

Fisher syndrome is recognized as a variant of Guillain-Barré syndrome, encompassing acute onset immune-mediated neuropathies marked by the classical triad of ataxia, areflexia, and ophthalmoplegia. Generally, Fisher syndrome follows a self-limited course with a good prognosis. Ophthalmoplegia, typically bilateral, progresses to complete external ophthalmoplegia within 1-2 weeks. Ataxia, often very severe, may cause an inability to walk without support despite normal strength. Fisher syndrome is also frequently concomitant with additional clinical features, including ptosis, internal ophthalmoplegia, facial nerve palsy, sensory deficits, and bulbar palsy. The confirmation of an antecedent infection is often established. Among the ganglioside antibodies, anti-GQ1b antibodies exhibit positivity in over 80% of patients. The syndrome manifests in three distinct types: a partial subtype exhibiting only a subset of the triad symptoms, Bickerstaff\'s brainstem encephalitis marked by impaired consciousness and pyramidal tract signs, and an overlapping subtype with Guillain-Barré syndrome, characterized by weakness in the extremities.

UNASSIGNED: The discovery of the anti-GQ1b antibody has expanded the nosology of classic Miller Fisher syndrome to include Bickerstaff brainstem encephalitis, Guillain-Barré syndrome with ophthalmoplegia, and acute ophthalmoplegia without ataxia, which have been brought under the umbrella term anti-GQ1b antibody syndrome. It seems timely to define the phenotypes of anti-GQ1b antibody syndrome for the proper diagnosis of this syndrome with diverse clinical presentations. This review summarizes these syndromes and introduces recently identified subtypes.
UNASSIGNED: Although ophthalmoplegia is a hallmark of anti-GQ1b antibody syndrome, recent studies have identified this antibody in patients with acute vestibular syndrome, optic neuropathy with disc swelling, and acute sensory ataxic neuropathy of atypical presentation. Ophthalmoplegia associated with anti-GQ1b antibody positivity is complete in more than half of the patients but may be monocular or comitant. The prognosis is mostly favorable; however, approximately 14% of patients experience relapse.
UNASSIGNED: Anti-GQ1b antibody syndrome may present diverse neurological manifestations, including ophthalmoplegia, ataxia, areflexia, central or peripheral vestibulopathy, and optic neuropathy. Understanding the wide clinical spectrum may aid in the differentiation and management of immune-mediated neuropathies with multiple presentations.

Miller Fisher syndrome is a rare and atypical variation of Guillain-Barré syndrome, which includes the clinical triad of areflexia, ataxia, and ophthalmoplegia. Miller Fisher syndrome is commonly associated with the involvement of the lower cranial and facial nerves. Miller Fisher syndrome is one of the types of Guillain-Barré syndrome. Guillain-Barré syndrome has been defined to be the foremost incapacitating form of neurological disease following the disease polio. Guillain-Barré syndrome is a broad category that encompasses several types of acute immune-mediated polyneuropathies, the most common of which is acute inflammatory demyelinating polyradiculoneuropathy. Here, we describe a case report of a 51-year-old patient who displayed the characteristic symptoms of Miller Fisher syndrome. We also describe the patient\'s clinical course, diagnostic method, and therapy. This case demonstrates the value of early detection, quick action in treating Miller Fisher syndrome, and the possibility of full recovery with adequate therapy. Techniques utilized in physical therapy emphasize performing everyday tasks along with strengthening muscles.

OBJECTIVE: Antiganglioside antibodies (AGAs) might be involved in the etiopathogenesis of many neurological diseases, such as Miller-Fisher syndrome (MFS) and Guillain-Barré syndrome (GBS). Available comprehensive reference data regarding AGA positivity rates and cross-responsiveness among AGAs (where one line immunoblot is positive for ≥1 AGA) during routine clinical care are scant.
METHODS: In this 10-year monocentric retrospective study, 3560 immunoglobulin (Ig) G and IgM line blots (GA Generic Assays\' Anti-Ganglioside Dot kit) obtained using cerebrospinal fluid (CSF) and serum samples from 1342 patients were analyzed for AGA positivity in terms of 14 diagnosis categories and AGA cross-responsiveness.
RESULTS: Of all 3560 line blots 158 (4.4%) and of all CSF samples 0.4% (4/924) CSF line blots were AGA positive. For serum IgG, blots with positivity rates higher than the standard deviation of 15.6% were associated with MFS (GD3, GD1a, GT1a and GQ1b) and acute motor axonal neuropathy (AMAN) (GM1, GD1a and GT1a). For serum IgM, blots with positivity rates higher than the standard deviation of 8.1% were associated with AMAN (GM2, GT1a and GQ1b), MFS (GM1, GT1a and GQ1b), multifocal motor neuropathy (MMN) (GM1, GM2 and GQ1b) and chronic inflammatory demyelinating polyneuropathy (CIDP) (GM1). Cross-responsiveness was observed in 39.6% of all positive serum AGA.
CONCLUSIONS: Testing for AGAs during routine clinical care rarely led to positive findings, both in serum and even less in CSF, except for the diagnoses AMAN, MFS, MMN and CIDP. Nonspecific findings found as cross-responsiveness between different AGA samples occur frequently, impacting the positivity of most AGA subtypes.