Miller-Fisher Syndrome: Are Anti-GAD Antibodies Implicated in Its Pathophysiology?

Anti-sulfatide antibody-related Guillain-Barré syndrome presenting with overlapping syndromes or severe pyramidal tract damage: a case report and literature review

Introduction

Anti-sulfatide antibodies are key biomarkers for the diagnosis of Guillain-Barré syndrome (GBS). However, case reports on anti-sulfatide antibody-related GBS are rare, particularly for atypical cases.

Case description case 1

A 63 years-old man presented with limb numbness and diplopia persisting for 2 weeks, with marked deterioration over the previous 4 days. His medical history included cerebral infarction, diabetes, and coronary atherosclerotic cardiomyopathy. Physical examination revealed limited movement in his left eye and diminished sensation in his extremities. Initial treatments included antiplatelet agents, cholesterol-lowering drugs, hypoglycemic agents, and medications to improve cerebral circulation. Despite this, his condition worsened, resulting in bilateral facial paralysis, delirium, ataxia, and decreased lower limb muscle strength. Treatment with intravenous high-dose immunoglobulin and dexamethasone resulted in gradual improvement. A 1 month follow-up revealed significant neurological sequelae.

Case description case 2

A 53 years-old woman was admitted for adenomyosis and subsequently experienced sudden limb weakness, numbness, and pain that progressively worsened, presenting with diminished sensation and muscle strength in all limbs. High-dose intravenous immunoglobulin, vitamin B1, and mecobalamin were administered. At the 1 month follow-up, the patient still experienced limb numbness and difficulty walking. In both patients, albuminocytologic dissociation was found on cerebrospinal fluid (CSF) analysis, positive anti-sulfatide antibodies were detected in the CSF, and electromyography indicated peripheral nerve damage.

Conclusion

Anti-sulfatide antibody-related GBS can present with Miller-Fisher syndrome, brainstem encephalitis, or a combination of the two, along with severe pyramidal tract damage and residual neurological sequelae, thereby expanding the clinical profile of this GBS subtype. Anti-sulfatide antibodies are a crucial diagnostic biomarker. Further exploration of the pathophysiological mechanisms is necessary for precise treatment and improved prognosis.

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.

Miller Fisher syndrome: an updated narrative review

Introduction

Miller Fisher syndrome (MFS) is considered a rare variant of Guillain-Barré syndrome (GBS), a group of acute-onset immune-mediated neuropathies characterized by the classic triad of ataxia, areflexia, and ophthalmoparesis. The present review aimed to provide a detailed and updated profile of all aspects of the syndrome through a collection of published articles on the subject, ranging from the initial description to recent developments related to COVID-19.

Methods

We searched PubMed, Scopus, EMBASE, and Web of Science databases and gray literature, including references from the identified studies, review studies, and conference abstracts on this topic. We used all MeSH terms pertaining to "Miller Fisher syndrome," "Miller Fisher," "Fisher syndrome," and "anti-GQ1b antibody."

Results

An extensive bibliography was researched and summarized in the review from an initial profile of MFS since its description to the recent accounts of diagnosis in COVID-19 patients. MFS is an immune-mediated disease with onset most frequently following infection. Anti-ganglioside GQ1b antibodies, detected in ~85% of patients, play a role in the pathogenesis of the syndrome. There are usually no abnormalities in MFS through routine neuroimaging. In rare cases, neuroimaging shows nerve root enhancement and signs of the involvement of the central nervous system. The most consistent electrophysiological findings in MFS are reduced sensory nerve action potentials and absent H reflexes. Although MFS is generally self-limited and has excellent prognosis, rare recurrent forms have been documented.

Conclusion

This article gives an updated narrative review of MFS with special emphasis on clinical characteristics, neurophysiology, treatment, and prognosis of MFS patients.

Recurrent Miller Fisher: A Case Report Along With a Literature and an EMG/NCS Review

MFS has been reported to recur in 10-12% of patients. There may be a genetic component related to HLA-DR2. Anti-GAD antibodies can be present in MFS along with anti-GQ1b. Common EMG/NCS associations consist of a predominantly axonal, sensory polyneuropathy and absent H reflexes. A 32-year-old female with a history of hypothyroidism presented to our institution twice with symptoms of diplopia, lower extremity weakness and distal paresthesias occurring a year apart. She had ophthalmoplegia, reduced reflexes, and ataxia on exam. CSF showed a borderline elevated protein of 47 and white blood cells <3. She was positive for anti-GQ1b both times. Her anti-GAD65 antibody was elevated during both admissions. EMG/NCS on her first admission revealed comparatively reduced sensory nerve action potentials (SNAPs) and a normal blink reflex. Her SNAPs improved on the second admission, however, the EMG was performed only 2 days after the onset of her symptoms, limiting some early findings that may have not matured electrophysiologically. She was treated with IVIG on both occasions with rapid recovery within 5 days. This case highlights the fact that MFS can be recurrent. It also provides further evidence that anti-GAD antibodies may be associated with MFS. Reported findings of the blink reflex in MFS are diverse and further data is needed to determine if certain findings are more predominant than others. Treatment typically consists of IVIG, though steroids may also be considered for recurrence. Prognosis is generally favorable, regardless of treatment.

Autoimmune Neurological Conditions Associated With Zika Virus Infection

Zika virus (ZIKV) is an emerging flavivirus rapidly spreading throughout the tropical Americas. Aedes mosquitoes is the principal way of transmission of the virus to humans. ZIKV can be spread by transplacental, perinatal, and body fluids. ZIKV infection is often asymptomatic and those with symptoms present minor illness after 3 to 12 days of incubation, characterized by a mild and self-limiting disease with low-grade fever, conjunctivitis, widespread pruritic maculopapular rash, arthralgia and myalgia. ZIKV has been linked to a number of central and peripheral nervous system injuries such as Guillain-Barré syndrome (GBS), transverse myelitis (TM), meningoencephalitis, ophthalmological manifestations, and other neurological complications. Nevertheless, mechanisms of host-pathogen neuro-immune interactions remain incompletely elucidated. This review provides a critical discussion about the possible mechanisms underlying the development of autoimmune neurological conditions associated with Zika virus infection.

Miller-Fisher syndrome after coronary artery bypass surgery

Miller–Fisher syndrome (MFS) is an uncommon neurological disorder that is considered a variant of the Guillain–Barre syndrome (GBS). It is clinically defined by a triad of symptoms, namely ataxia, areflexia and ophthalmoplegia. These acute inflammatory polyradiculopathic syndromes can be triggered by viral infections, major surgery, pregnancy or vaccination. While the overall incidence of GBS is 1.2–2.3 per 100 000 per year, MFS is a relatively rare disorder. Only six cases of GBS after cardiac surgery have been reported, and to our knowledge, we describe the first case of MFS after coronary artery bypass surgery. Although cardiac surgery with cardiopulmonary bypass may increase the incidence of MFS and GBS, the pathological mechanism is unclear. Cardiac surgery may be a trigger for the immune-mediated response and may cause devastating complications. It is also important to be alert to de novo autoimmune and unexpected neurological disorders such as MFS after coronary bypass surgery.

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.