Opsoclonus-Myoclonus-Ataxia Syndrome Due to Covid-19

Opsoclonus-myoclonus syndrome (OMS) as a rare neurological encephalopathic entity associated with non-specific infections or cancer processes has been repeatedly described in the setting of SARS-CoV-2 infection. We report a case of a 53-year-old man with SARS-CoV-2 infection, who developed clinical features of opsoclonus-myoclonus ataxia syndrome including cognitive impairments with a prolonged course of disease. Of particular note, cerebrospinal fluid (CSF) analysis revealed the production of myelin oligodendrocyte glycoprotein (MOG) antibodies, suggesting an underlying neuroimmunological mechanism associated with infection with the novel SARS-CoV-2 virus.

Autoimmune central nervous system disorders: Antibody testing and its clinical utility

A rapidly expanding repertoire of neural antibody biomarkers exists for autoimmune central nervous system (CNS) disorders. Following clinical recognition of an autoimmune CNS disorder, the detection of a neural antibody facilitates diagnosis and informs prognosis and management. This review considers the phenotypes, diagnostic assay methodologies, and clinical utility of neural antibodies in autoimmune CNS disorders. Autoimmune CNS disorders may present with a diverse range of clinical features. Clinical phenotype should inform the neural antibodies selected for testing via the use of phenotype-specific panels. Both serum and cerebrospinal fluid (CSF) are preferred in the vast majority of cases but for some analytes either CSF (e.g. N-methyl-D-aspartate receptor [NMDA-R] IgG) or serum (e.g. aquaporin-4 [AQP4] IgG) specimens may be preferred. Screening using 2 methods is recommended for most analytes, particularly paraneoplastic antibodies. We utilize murine tissue-based indirect immunofluorescence assay (TIFA) with subsequent confirmatory protein-specific testing. The cellular location of the target antigen informs choice of confirmatory diagnostic assay (e.g. blot for intracellular antigens such as Hu; cell-based assay for cell surface targets such as leucine-rich glioma inactivated 1 [LGI1]). Titers of positive results have limited diagnostic utility with the exception of glutamic acid decarboxylase (GAD) 65 IgG autoimmunity, which is associated with neurological disease at higher values. While novel antibodies are typically discovered using established techniques such as TIFA and immunoprecipitation-mass spectrometry, more recent high-throughput molecular technologies (such as protein microarray and phage-display immunoprecipitation sequencing) may expedite the process of antibody discovery. Individual neural antibodies inform the clinician regarding the clinical associations, oncological risk stratification and tumor histology, the likely prognosis, and immunotherapy choice. In the era of neural antibody biomarkers for autoimmune CNS disorders, access to appropriate laboratory assays for neural antibodies is of critical importance in the diagnosis and management of these disorders.

Powassan Virus Encephalitis: A Tertiary Center Experience

BACKGROUND

Powassan virus (POWV) is an emerging arthropod-borne flavivirus, transmitted by Ixodes spp. ticks, which has been associated with neuroinvasive disease and poor outcomes.

METHODS

A retrospective study was conducted at Mayo Clinic from 2013 to 2022. We included clinical and epidemiologic data of probable and confirmed neuroinvasive POWV cases.

RESULTS

Sixteen patients with neuroinvasive POWV were identified; their median age was 63.2 years, and 62.5% were male. Six patients presented with rhombencephalitis, 4 with isolated meningitis, 3 with meningoencephalitis, 2 with meningoencephalomyelitis, and 1 with opsoclonus myoclonus syndrome. A median time of 18 days was observed between symptom onset and diagnosis. Cerebrospinal fluid analysis showed lymphocytic pleocytosis with elevated protein and normal glucose in the majority of patients. Death occurred within 90 days in 3 patients (18.8%), and residual neurologic deficits were seen in 8 survivors (72.7%).

CONCLUSIONS

To our knowledge, this is the largest case series of patients with neuroinvasive POWV infection. We highlight the importance of a high clinical suspicion among patients who live in or travel to high-risk areas during the spring to fall months. Our data show high morbidity and mortality rates among patients with neuroinvasive disease.

Overview of management of infection-related movement disorders with focus on specific-infections

Infections are important treatable causes of secondary movement disorders (MD) that can have heterogeneous presentations. According to various studies, infection-related movement disorders (IRMD) account for around 10-20% of secondary MD. Certain infections have a predilection for causing various MD, and some MD phenomenologies, such as acute cerebellar ataxia and opsoclonus-myoclonus-ataxia syndromes (OMAS), suggest a strong possibility of an underlying infectious cause. The underlying pathophysiology is multifaceted, including direct neuronal damage due to neurotropism, granulomas, abscesses causing structural damage, and inflammatory and autoimmune responses triggered by infections. Understanding the prevalence, spectrum, and pattern of these IRMD and common infections that are responsible helps in early diagnosis, and instituting appropriate, timely treatment, thereby improving the overall prognosis and avoiding unnecessary investigations. In this review, we aim to provide a brief overview of common infections associated with MD, common clinical presentations of IRMD, their underlying pathophysiology, and overall approach to their treatment, with a focus on specific treatments of prevalent and treatable IRMD.

Clinical approach to diagnosis of paraneoplastic neurologic syndromes

The correct diagnosis of a paraneoplastic neurologic syndrome (PNS) first requires the identification of the syndrome as one of those defined as high-risk (previously called classical) or intermediate-risk for cancer in the 2021 PNS diagnostic criteria. Testing for neuronal antibodies should be restricted to these syndromes as indiscriminate request decreases the diagnostic value of the antibodies. Identifying onconeural (high-risk for cancer) or intermediate-risk for cancer antibodies supports the paraneoplastic diagnosis and mandates the search for an underlying cancer. Tumor screening must follow the published guidelines. Repeated screening is indicated in neurologic syndromes with onconeural antibodies and patients with high-risk for cancer neurologic syndromes unless they present neuronal antibodies which are not associated with cancer. Neuronal antibodies should be screened by immunohistochemistry and confirmed by immunoblot (intracellular antigens) or cell-based assay (CBA) (surface antigens). Positive results only by immunoblot or CBA should be taken with caution. Although the 2021 diagnostic criteria for PNS do not capture all PNS, as they do not allow to diagnose definite PNS neurologic syndromes without neuronal antibodies, the updated criteria represent a step forward to differentiate true PNS from neurologic syndromes that coincide in time with cancer diagnosis without having a pathogenic link.

Rare Presentation and Diagnostic Challenge of a Germ Cell Tumor of the Yolk Sac Type

Opsoclonus-ataxia paraneoplastic syndrome (OAPS) is a rare neurological disorder often associated with malignancies. This case report highlights an unusual instance of OAPS linked to a yolk sac (germ cell) tumor, a correlation underrepresented in the medical literature. The patient presented with distinct neurological symptoms alongside mediastinal lymphadenopathies. The subsequent diagnostic journey revealed a yolk sac germ cell tumor. Following incisional biopsies and treatment, the patient experienced fluctuations in mental status, leading to challenges in initiating chemotherapy. Despite these complications, a multidisciplinary approach involving neurologists, oncologists, and hematologists was pivotal. The case emphasizes the complexities of managing OAPS in tandem with a germ cell tumor, underscoring the need for further research and highlighting the significance of specialized neurological evaluation in similar cases.

Paraneoplastic Neurologic Syndromes

OBJECTIVE

Progress is ongoing in understanding paraneoplastic neurologic disorders, with new syndromes and antibodies being described and more detailed evidence available to guide workup for diagnosis and treatment to improve outcomes. Many excellent reviews have summarized the molecular features of different antibodies, but this article emphasizes the clinical features of each syndrome that may help guide initial diagnosis and treatment, which often should occur before an antibody or cancer is found to confirm the diagnosis.

LATEST DEVELOPMENTS

Recent findings include updated diagnostic criteria with validated sensitivity and specificity, discovery of novel antibodies, and clinical findings that increase the likelihood of an underlying paraneoplastic disorder. Suggestive syndromes that have been recently identified include faciobrachial dystonic seizures and pilomotor auras in anti-leucine-rich glioma inactivated protein 1 encephalitis, extreme delta brush on EEG in N-methyl-d-aspartate (NMDA)-receptor encephalitis, déjà vu aura in anti-glutamic acid decarboxylase 65 (GAD65) encephalitis, and sleep disturbances in several disorders. In addition, there is confirmed utility of brain positron emission tomography (PET) and CSF markers, including carcinoembryonic antigen and oligoclonal bands, as well as improved tests for the presence of leptomeningeal cancer cells in CSF. Associations of cancer immunotherapies with paraneoplastic syndromes and herpes simplex virus encephalitis (and COVID-19) with NMDA-receptor encephalitis have been described.

ESSENTIAL POINTS

All neurologists should be aware of advances regarding paraneoplastic neurologic syndromes, as patients can present with a wide variety of neurologic symptoms and earlier diagnosis and treatment can improve outcomes.

Immune-mediated ataxias: Guide to clinicians

Immune-mediated cerebellar ataxias were initially described as a clinical entity in the 1980s, and since then, an expanding body of evidence has contributed to our understanding of this topic. These ataxias encompass various etiologies, including postinfectious cerebellar ataxia, gluten ataxia, paraneoplastic cerebellar degeneration, opsoclonus-myoclonus-ataxia syndrome and primary autoimmune cerebellar ataxia. The increased permeability of the brain-blood barrier could potentially explain the vulnerability of the cerebellum to autoimmune processes. In this manuscript, our objective is to provide a comprehensive review of the most prevalent diseases within this group, emphasizing clinical indicators, pathogenesis, and current treatment approaches.

A Case of Paraneoplastic Neurological Syndrome Leading to the Diagnosis of Large Cell Neuroendocrine Carcinoma From Opsoclonus-Myoclonus Syndrome

Opsoclonus-myoclonus syndrome (OMS) is a rare neurological disorder characterized by myoclonus, ataxia, and tremors. It can be classified as neoplastic or idiopathic, with small cell lung cancer being commonly associated. Herein, we present a rare case of refractory paraneoplastic neurological syndrome (PNS) caused by large cell neuroendocrine carcinoma (LCNEC), a rare form of non-small cell lung cancer (NSCLC). A 60-year-old otherwise healthy man presented with acute-onset dysarthria, gait instability, and numbness on the right side of his body. According to the clinical symptoms and neurological examination, we initially suspected cerebellar infarction; however, brain imaging revealed no abnormal findings. After a few days, the patient developed worsening horizontal nystagmus, irregular ocular rhythms, and generalized involuntary movements, indicative of OMS. A systemic evaluation revealed a solitary nodule in the lower lobe of the right lung, leading to a clinical diagnosis of PNS. The patient underwent segmentectomy to treat an early-stage LCNEC nodule after one month from onset. Despite all therapeutic interventions, OMS was refractory, and after consulting with the person himself and the family, palliative care was selected. However, the patient showed a clinical response belatedly five months after surgery. This case highlights the importance of considering PNS, and that it may be associated with a rare malignancy when cerebellar symptoms are observed, and the challenges in managing refractory PNS associated with rare forms of NSCLC.

Opsoclonus and ocular flutter: evaluation and management

PURPOSE OF REVIEW

Opsoclonus and ocular flutter are saccadic intrusions characterized by spontaneous, back-to-back, fast eye movements (saccades) that oscillate about the midline of central visual fixation without intervening inter-saccadic intervals. When this type of movement occurs exclusively in the horizontal plane, it is called ocular flutter. When it occurs in multiple planes (i.e. horizontal, vertical, and torsional) it is called opsoclonus. The most common etiologic categories are parainfectious and paraneoplastic diseases. Less common are toxic-metabolic, traumatic, or idiopathic origins. The mechanism of these movements relates to dysfunction of brainstem and cerebellar machinery involved in the generation of saccades. In this review, we discuss the characteristics of opsoclonus and ocular flutter, describe approaches to clinical evaluation and management of the patient with opsoclonus and ocular flutter, and review approaches to therapeutic intervention.

RECENT FINDINGS

Recent publications demonstrated eye position-dependent opsoclonus present only in left gaze, which may be related to dysfunction of frontal eye fields or structures in the cerebellar vermis.

SUMMARY

Opsoclonus and ocular flutter originate from a broad array of neuropathologies and have value from both a neuroanatomic and etiologic perspective.

Diagnosis and Treatment of Paraneoplastic Neurologic Syndromes

Paraneoplastic antibody syndromes result from the anti-tumor antibody response against normal antigens ectopically expressed by tumor cells. Although this antibody response plays an important role in helping clear a nascent or established tumor, the engagement of antigens expressed in healthy tissues can lead to complex clinical syndromes with challenging diagnosis and management. The majority of known paraneoplastic antibody syndromes have been found to affect the central and peripheral nervous system. The present review provides an update on the pathophysiology of paraneoplastic neurologic syndromes, as well as recommendations for their diagnosis and treatment.

A Rare Case of Opsoclonus Myoclonus Ataxia Syndrome Post Viral Illness

Opsoclonus myoclonus ataxia syndrome (OMAS) is a rare inflammatory neurological disorder characterized by ocular, motor, behavioral, language, and sleep disturbances. It usually affects infants and young children but may affect adults. A 28-year-old male was brought to our emergency ward with complaints of involuntary spontaneous eye movements and jerky movements of limbs with imbalance while walking. He had a history of short febrile illness 10 days prior. His magnetic resonance imaging (MRI) of the brain, cerebrospinal fluid (CSF) analysis, and other routine investigations were normal. The patient was treated with injectable methylprednisolone (1 g) given for five days along with other supportive therapy. A significant reduction in the opsoclonus, myoclonus, and ataxia was seen on a six-month follow-up. OMAS should be identified early to avoid the use of inappropriate medications, and immunotherapy must be provided as early as possible in order to prevent irreversible neurological damage.

An eye to the future: Acute and long-term neuro-ophthalmological and neurological complications of COVID-19

COVID-19 has had a significant impact on the global population and has produced compelling evidence of non-pulmonary organ dysfunction, including the nervous system. It is vital that specialists in ophthalmology and neurology are informed of the potential complications of COVID-19 and gain a deeper understanding of how COVID-19 can cause diseases of the nervous system. In this review we detail four possible mechanisms by which COVID-19 infection may result in neurological or neuro-ophthalmological complications: (1) Toxic and metabolic effects of severe pulmonary COVID-19 disease on the neural axis including hypoxia and the systemic hyper-inflammatory state, (2) endothelial dysfunction, (3) dysimmune responses directed again the neuroaxis, and (4) direct neuro-invasion and injury by the virus itself. We explore the pathological evidence for each of these and how they may link to neuro-ophthalmological disorders. Finally, we explore the evidence for long-term neurological and neuro-ophthalmological complications of COVID-19, with a focus on neurodegeneration.

Paraneoplastic Neurologic Disorders

PURPOSE OF REVIEW

To provide an overview and highlight recent updates in the field of paraneoplastic neurologic disorders.

RECENT FINDINGS

The prevalence of paraneoplastic neurologic disorders is greater than previously reported and the incidence has been rising over time, due to improved recognition in the era of antibody biomarkers. Updated diagnostic criteria that are broadly inclusive and also contain diagnostic risk for clinical presentations (high and intermediate) and diagnostic antibodies (high, intermediate, and low) have replaced the original 2004 criteria. Antibody biomarkers continue to be characterized (e.g., KLHL-11 associated with seminoma in men with brainstem encephalitis). Some paraneoplastic antibodies also provide insight into likely immunotherapy response and prognosis. The rise of immune checkpoint inhibitors as cancer therapeutics has been associated with newly observed immune-mediated adverse effects including paraneoplastic neurological disorders. The therapeutic approach to paraneoplastic neurologic disorders is centered around cancer care and trials of immune therapy. The field of paraneoplastic neurologic disorders continues to be advanced by the identification of novel antibody biomarkers which have diagnostic utility, and give insight into likely treatment responses and outcomes.

Neurology of Systemic Disease

Sex differences exist within the neurologic complications of systemic disease. To promote new avenues for prevention and develop novel therapeutics, we highlight the role of sex in differential outcomes to infectious disease and cardiac arrest and educate the reader in paraneoplastic presentations that may herald underlying malignancies in women.

Opsoclonus-myoclonus syndrome caused by organophosphate poisoning

Opsoclonus-myoclonus syndrome is a combination of involuntary, arrhythmic, conjugate saccadic eye movements with myoclonus. The most common cause in adults is paraneoplastic encephalitis. Rarer causes include infections such as scrub typhus, and toxins such as organophosphates and cocaine. Organophosphates are one of the common poisonings in tropical countries such as India, causing both central and peripheral nervous system manifestations. We describe a middle-aged male farmer with unexplained altered consciousness and respiratory depression. After 2 days, he developed opsoclonus-myoclonus, and then bronchorrhoea and bradycardia, raising suspicion of organophosphate poisoning. After we had identified a very low serum cholinesterase concentration, he disclosed having consumed organophosphates.

Paraneoplastic Opsoclonus-Myoclonus Syndrome as a Rare Presentation of Small-Cell Lung Cancer

Opsoclonus-myoclonus syndrome (OMS), also known as Kinsbourne syndrome or dancing eyes syndrome, is an extremely rare neurological condition that comprises a heterogenous constellation of symptoms including opsoclonus along with diffuse or focal body myoclonus. It is usually referred to as a paraneoplastic entity, but it may also be associated to an infectious, metabolic, or idiopathic cause. Small-cell carcinoma of the lung is the most commonly reported malignancy associated with OMS. The authors describe a case of a 69-year-old male that presented with ataxic gait, phono- and photophobia, vertigo, dizziness, lethargy, nausea, and vomiting. During examination, rapid, multidirectional eye movements; slight dysarthria; and facial myoclonus were noted. He was admitted to the hospital, and after a thorough study, a diagnosis of OMS was established. Intravenous corticosteroids were started, alongside physiotherapy, and a slight improvement of his symptoms was noted. Imaging revealed a suspicious lesion in the left lung, along with lymphadenopathies and bone metastases. Histology confirmed the diagnosis of stage IV small-cell lung cancer (SCLC). Chemotherapy (ChT) with carboplatin and etoposide was started, and a gradual improvement of his neurological complaints was noted. After six cycles, the disease progressed, and second-line ChT with topotecan was started. After two cycles, the patient experienced significant clinical deterioration and eventually died. In conclusion, OMS is a poorly understood condition with uncertain neurological prognosis. The treatment of the primary neoplasm may improve neurological symptoms. The recognition of paraneoplastic syndromes is of utmost importance since early diagnosis of a malignancy relates to better outcomes.

Clinical features and outcomes of opsoclonus myoclonus ataxia syndrome

OBJECTIVES AND METHODS

Opsoclonus myoclonus ataxia syndrome (OMAS) is a rare neuroinflammatory disorder. We aimed to retrospectively evaluate clinical and laboratory data and outcomes of 23 children diagnosed with OMAS in two children's hospitals between 2010 and 2021.

RESULTS

There were 14 boys and 9 girls aged 4-113 months, median 24 months. Ten (43.5%) children had paraneoplastic causes: neuroblastoma/ganglioneuroblastoma (n = 9), acute lymphoblastic leukemia (n = 1). Three children had a postinfectious cause (upper respiratory tract infection in 2, EBV infection in 1) and two had a history of vaccination (varicella in 1, hepatitis A and meningococcal in 1). No underlying factor was identified in 8 (34.8%) children. Speech disorders were more frequent in patients with neural tumors than in those without (p = 0.017). Intravenous immunoglobulin and steroids were effective as initial treatment in most children. Rituximab resulted in at least mild improvement in all 6 children with persistent or recurrent symptoms. Nine (39%) children experienced at least one relapse. Neurological sequelae were detected in 13 (57%) children. There was no significant correlation between clinical characteristics and outcome, except for higher risk of relapse in case of incomplete recovery after first attack (p = 0.001).

CONCLUSIONS

Acute lymphoblastic leukemia, vaccines against hepatitis A and meningococci can be included among antecedent factors in OMAS. Among clinical symptoms, speech problems might point to the likelihood of an underlying neoplasm in OMAS. Intravenous immunoglobulin and steroids may be chosen for initial treatment while rituximab can increase the chance of recovery in case of persistent or recurrent symptoms. The presence of relapse was associated with poor outcome.

Opsoclonus-myoclonus paraneoplastic syndrome in nasopharyngeal carcinoma

Nasopharyngeal carcinoma can present with epistaxis, cervical lymphadenopathy, audiological symptoms secondary to eustachian tube dysfunction, pain, or neurological symptoms from tumours directly invading the skull base. It is unusual for patients to present with indirect systemic manifestations. Paraneoplastic neurological syndrome can precede clinically overt malignancy by up to 5 years; therefore, a combination of thorough clinical, laboratory and radiological investigations is required to reach a diagnosis. Intravenous immunoglobulin and steroids might improve neurological symptoms initially and prevent irreversible neuronal damage, but treatment of the underlying cancer is important for long-term resolution. Our case adds to a small but growing body of literature related to anti-Ri antibodies, opsoclonus-myoclonus syndrome presentations, and is the first reported association of this combination with nasopharyngeal carcinoma.

Breast Cancer Presenting As Onconeural Antibody Negative Opsoclonus-Myoclonus Syndrome

Breast cancer can rarely present with or be preceded by paraneoplastic syndromes such as opsoclonus-myoclonus syndrome (OMS). OMS is a rare neurological syndrome that commonly presents with symptoms of rapid, chaotic eye movements (opsoclonus), jerking involuntary muscle movements (myoclonus) and is frequently associated with ataxia. We describe a case of a woman in her early 50s who presented to the emergency room (ER) with vertigo, jerking movements, loss of fine motor skills and gait abnormalities. She was initially thought to have likely vestibular neuritis and was treated symptomatically and discharged home. However, the symptoms persisted and she presented once again to the ER, at which time she also incidentally discovered a lump in her breast. This led to her being investigated more extensively leading to a diagnosis of underlying primary breast cancer. Based on her neurological clinical findings, she was diagnosed with onconeural antibody negative OMS. Treatment of her underlying malignancy led to a significant improvement in her symptoms. Paraneoplastic neurological syndromes (PNSs) are an important differential diagnosis to consider in patients presenting with persistent, treatment-resistant and non-specific neurological symptoms. Any suspicion of the same should prompt a search for an underlying malignancy that could greatly influence patient outcomes.

Idiopathic generalised tremor syndrome in dogs

BACKGROUND

Idiopathic generalised tremor syndrome (IGTS) causes tremor and often vestibulocerebellar signs. Previous publications on IGTS in dogs are restricted to case reports or lack exclusion of structural causes.

METHODS

Medical records of 75 dogs diagnosed with IGTS that had undergone magnetic resonance imaging (MRI) of the brain were collected retrospectively.

RESULTS

Crossbreeds were affected most commonly (41.3%), followed by West Highland white terriers (14.7%) and cocker spaniels (10.7%). A higher proportion of females were affected than males (68.0%). Median age of the affected dogs was 17 months (range 6-121 months), and median bodyweight was 9.15 kg (range 2.9-26 kg). All dogs presented with tremors and most experienced concomitant neurological signs (93.3%). Seventeen (22.7%) were hyperthermic and 31 (41.3%) had gastrointestinal signs. MRI of the brain was normal in most of the cases, and cerebrospinal fluid analysis frequently revealed mild pleocytosis. All animals were treated with prednisolone, and 39 (51.3%) also received diazepam. Median follow-up time was 13 months (range 0-134 months). The overall outcome was good, although 16 (21.3%) patients were reported to have relapsing clinical signs and 10 (13.2%) patients experienced persistent mild clinical signs.

CONCLUSIONS

IGTS should be suspected in any dog with generalised tremor and vestibulocerebellar signs with younger and smaller dogs more commonly affected.

Postinfectious SARS-CoV-2 Opsoclonus-Myoclonus-Ataxia Syndrome

BACKGROUND

The opsoclonus-myoclonus-ataxia syndrome (OMAS) represents a pathophysiology and diagnostic challenge. Although the diverse etiologies likely share a common mechanism to generate ocular, trunk, and limb movements, the underlying cause may be a paraneoplastic syndrome, as the first sign of cancer, or may be a postinfectious complication, and thus, the outcome depends on identifying the trigger mechanism. A recent hypothesis suggests increased GABAA receptor sensitivity in the olivary-oculomotor vermis-fastigial nucleus-premotor saccade burst neuron circuit in the brainstem. Therefore, OMAS management will focus on immunosuppression and modulation of GABAA hypersensitivity with benzodiazepines.

METHODS

We serially video recorded the eye movements at the bedside of 1 patient with SARS-CoV-2-specific Immunoglobulin G (IgG) serum antibodies, but twice-negative nasopharyngeal reverse transcription polymerase chain reaction (RT-PCR). We tested cerebrospinal fluid (CSF), serum, and nasopharyngeal samples. After brain MRI and chest, abdomen, and pelvis CT scans, we treated our patient with clonazepam and high-dose Solu-MEDROL, followed by a rituximab infusion after her formal eye movement analysis 10 days later.

RESULTS

The recordings throughout her acute illness demonstrated different eye movement abnormalities. While on high-dose steroids and clonazepam, she initially had macrosaccadic oscillations, followed by brief ocular flutter during convergence the next day; after 10 days, she had bursts of opsoclonus during scotopic conditions with fixation block but otherwise normal eye movements. Concern for a suboptimal response to high-dose Solu-MEDROL motivated an infusion of rituximab, which induced remission. An investigation for a paraneoplastic etiology was negative. CSF testing showed elevated neuron-specific enolase. Serum IgG to Serum SARS-CoV2 IgG was elevated with negative RT-PCR nasopharyngeal testing.

CONCLUSION

A recent simulation model of macrosaccadic oscillations and OMAS proposes a combined pathology of brainstem and cerebellar because of increased GABAA receptor sensitivity. In this case report, we report 1 patient with elevated CSF neuronal specific enolase, macrosaccadic oscillations, ocular flutter, and OMAS as a SARS-CoV-2 postinfectious complication. Opsoclonus emerged predominantly with fixation block and suppressed with fixation, providing support to modern theories on the mechanism responsible for these ocular oscillations involving cerebellar-brainstem pathogenesis.

Eye Movement Disorders in Movement Disorders

Oculomotor assessment is an essential element of the neurological clinical examination and is particularly important when evaluating patients with movements disorders. Most of the brain is involved in oculomotor control, and thus many neurological conditions present with oculomotor abnormalities. Each of the different classes of eye movements and their features can provide important information that can facilitate differential diagnosis. This educational review presents a clinical approach to eye movement abnormalities that are commonly seen in parkinsonism, ataxia, dystonia, myoclonus, tremor, and chorea. In parkinsonism, subtle signs such as prominent square wave jerks, impaired vertical optokinetic nystagmus, and/or the "round the houses" sign suggest early progressive supranuclear gaze palsy before vertical gaze is restricted. In ataxia, nystagmus is common, but other findings such as oculomotor apraxia, supranuclear gaze palsy, impaired fixation, or saccadic pursuit can contribute to diagnoses such as ataxia with oculomotor apraxia, Niemann-Pick type C, or ataxia telangiectasia. Opsoclonus myoclonus and oculopalatal myoclonus present with characteristic phenomenology and are usually easy to identify. The oculomotor exam is usually unremarkable in isolated dystonia, but oculogyric crisis is a medical emergency and should be recognized and treated in a timely manner. Gaze impersistence in a patient with chorea suggests Huntington's disease, but in a patient with dystonia or tremor, Wilson's disease is more likely. Finally, functional eye movements can reinforce the clinical impression of a functional movement disorder.

[Manifestations of the central nervous system after COVID-19]

Numerous diseases of the central nervous system (CNS), especially in the postacute phase after an infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have been described. These include neuroimmunologically mediated diseases, such as encephalopathy, encephalitis, myelitis, acute disseminated encephalomyelitis (ADEM), acute necrotizing hemorrhagic leukoencephalitis (ANHLE) and neuromyelitis optica spectrum disorder (NMOSD) as well as others, such as posterior reversible encephalopathy syndrome (PRES), opsoclonus myoclonus ataxia (OMA) and cerebrovascular diseases. A parainfectious or postinfectious association is discussed but the pathophysiological mechanisms are so far unknown. Underlying mechanisms could be a virus-triggered overactivation of the immune system with hyperinflammation and cytokine storm but possibly also the development of specific autoantibodies against CNS tissue. Direct damage due to the invasion of SARS-CoV‑2 into the brain or spinal cord does not seem to play a relevant role. An exact clinical phenotyping and initiation of additional diagnostics are recommended, also to rule out other causes. To date no medicinal treatment options for CNS manifestations of long COVID exist; however, first results regarding inflammation and autoimmunity are promising and could lead to new treatment approaches.

Case Report: Opsoclonus-Myoclonus Syndrome Associated With Contactin-Associated Protein-Like 2 and Acetylcholine Receptor Autoantibodies in the Setting of Non-Small Cell Lung Carcinoma

Opsoclonus myoclonus syndrome (OMS) is a rare immune-mediated paraneoplastic or para/-post-infectious syndrome characterized by "dancing" eye movements, myoclonus, and ataxia. Neuropsychiatric symptoms have also been reported. Without treatment, OMS may progress to further neurological impairment and even death. Autoimmune attack of CNS structures in OMS is most commonly mediated by anti-Ri (also known as ANNA2) IgG antibodies, with additional findings implicating antibodies targeting various neurotransmitter receptors. Prompt immunotherapy and neoplasm treatment may result in improvement. We report a novel association of Contactin-Associated Protein-Like 2 (Caspr2) antibodies occurring in association with paraneoplastic OMS. While breast cancer and small cell lung cancer (SCLC) are more commonly associated with OMS among adults, we characterize a novel association between Caspr2 antibody in a patient with mixed non-small cell and small cell lung carcinoma.

Treatable Hyperkinetic Movement Disorders Not to Be Missed

Hyperkinetic movement disorders are characterized by the presence of abnormal involuntary movements, comprising most notably dystonia, chorea, myoclonus, and tremor. Possible causes are numerous, including autoimmune disorders, infections of the central nervous system, metabolic disturbances, genetic diseases, drug-related causes and functional disorders, making the diagnostic process difficult for clinicians. Some diagnoses may be delayed without serious consequences, but diagnosis delays may prove detrimental in treatable disorders, ranging from functional disabilities, as in dopa-responsive dystonia, to death, as in Whipple's disease. In this review, we focus on treatable disorders that may present with prominent hyperkinetic movement disorders.

Breast cancer-associated opsoclonus-myoclonus syndrome: a case report

Background

Paraneoplastic neurological syndromes constitute rare neurological complications of malignant disease, manifesting in <1% of patients with cancer. Opsoclonus-myoclonus syndrome (OMS) presents with chaotic ocular saccades (opsoclonus), spontaneous muscular jerking (myoclonus) that may be accompanied by ataxia, strabismus, aphasia, or mutism. Its paraneoplastic variant in the adult is most commonly associated with small-cell lung cancer, followed by breast cancer. Importantly, neurological symptoms usually precede the diagnosis of breast cancer and tend to recure after its treatment.

Case presentation

A 43-year-old premenopausal Caucasian woman with a medical history of hypertension was admitted following an episode of focal seizure. This progressed to generalised tonic-clonic seizures and she was subsequently loaded with phenytoin, valproate, and levetiracetam. Initial workup included whole body CT scan, viral and autoimmune serology. The CT scan revealed an enhancing right axillary lymph node, which in combination with Anti-Ri antibody positivity raised the spectre of paraneoplastic OMS. MRI of the head revealed subtle nonspecific white matter signal change within the centrum semiovale without any mass lesions, while MRI of the spine was unremarkable. An uncomplicated right mastectomy and axillary lymph node clearance was performed: histopathology revealed a 9-mm, grade 2, oestrogen receptor-positive, progesterone receptor-negative (ER8, PR0), Her2-negative invasive ductal carcinoma, and 4/6 positive lymph nodes (T1b N2 M0). Two months later, she was readmitted with vertigo, diplopia, facial weakness, and ataxia, setting the diagnosis anti-Ri syndrome recurrence. MDT recommended mammogram and ultrasound of the left breast, which were normal. Subsequently, four months after initial discharge, she suffered another neurological recurrence; due to concomitant abdominal pain, PET-CT was performed demonstrating a hypermetabolic right ovarian focus. Bilateral salpingo-oophorectomy was performed as per gynaecology MDT and final histology showed normal tubes and ovaries. She has remained on remission since then, with a negative annual mammogram follow-up.

Conclusions

In conclusion, we report a case of OMS associated with breast cancer anti-Ri onconeural antibody. Its manifestations preceded the diagnosis of malignancy and it persisted after cancer treatment, underlining the importance for high clinical suspicion in cases of classical paraneoplastic neurological syndromes as well as the need for long-term clinical follow-up.

Unusual Movement Disorders and Atypical Magnetic Resonance Imaging (MRI) Findings in Patients with West Nile Encephalitis: Case Reports of 2 Patients with Evidence of Clinical and Imaging Resolution with IVIG

BACKGROUND West Nile virus (WNv) is the leading cause of epidemic arbovirus encephalitis in the continental United States. Movement disorders (MDs) have been reported in 20% to 40% of patients with WNv and about 37% of patients with WNv encephalitis have changes on magnetic resonance imaging (MRI). We report 2 unusual cases of neuroinvasive WNv in patients with unusual MDs and unreported MRI findings. CASE REPORT In the first case, a 34-year-old man presented with a 1-week history of disinhibition, agitation, opsoclonus-myoclonus and ataxia syndrome (OMAS), tremor, and facial agnosia. Evaluation of his cerebrospinal fluid (CSF) revealed elevated immunoglobulin (Ig)M against WNv, a high level of protein (98 mg/dL), and an elevated white blood cell (WBC) count (134, 37% lymphocytes). An MRI of the brain showed an area of diffusion restriction in the splenium of the corpus callosum. The patient's MRI findings and OMA improved significantly after 2 treatments with i.v. IG (IVIG). In the second case, a 57-year-old woman presented with fever, headaches, psychosis, and ataxia; she was subsequently intubated for airway protection. Analysis of her CSF showed elevated IgM against WNv, a high level of protein (79 mg/dL), and elevated WBC count (106, 90% lymphocytes). One week after the onset of symptoms, the patient experienced facial dyskinesia. Later, she developed proximal bilateral lower extremity weakness. An MRI of her lumbar spine showed evidence of myeloradiculitis with contrast enhancement of the conus medullaris and ventral nerve roots. After a single treatment with IVIG, she had partial improvement in weakness. CONCLUSIONS MDs and changes on MRI have been reported in patients with neuroinvasive WNv disease. Our patient with OMAS also had transient splenial diffusion restriction on imaging, which, to the best of our knowledge, has not been previously reported with WNv infection. In both patients, treatment with IVIG resulted in improvement in symptoms.

New-Onset Refractory Status Epilepticus (NORSE) as a Recurrence of Anti-Neuronal Nuclear Antibody 2 (ANNA-2) Encephalitis After Immune Checkpoint Inhibition Therapy

Paraneoplastic encephalitis from anti-neuronal nuclear antibody 2 (ANNA-2), usually associated with breast cancer, can cause seizures. We report a case of recurrent paraneoplastic encephalitis due to ANNA-2 presenting with new-onset refractory status epilepticus (NORSE) one month after receiving checkpoint inhibitors therapy.

A 69-year-old female was diagnosed with opsoclonus myoclonus syndrome (OMS) secondary to ANNA-2, which led to a diagnosis of breast cancer. OMS improved with surgical resection and intravenous immunoglobulin (IVIG). Three years later, she was diagnosed with metastatic cancer to the liver and spine. She underwent immune checkpoint inhibitor therapy. One month later, she was admitted with NORSE. Opsoclonus was seen at the physical exam. Brain MRI and infectious work-up were unremarkable. Cerebrospinal fluid (CSF) analysis revealed pleocytosis with lymphocytic predominance. She was treated with corticosteroids and immunoglobulins, and she had symptomatic improvement. ANNA-2 test was positive in a lower titration than three years earlier.

Opsoclonus in a patient with NORSE can be the hint of ANNA-2 positivity. Immune checkpoint inhibitor therapy should be carefully reconsidered in patients with a history of paraneoplastic encephalitis for ANNA-2 as it could precipitate NORSE.

Opsoclonus-myoclonus syndrome with severe clinical course and beneficial outcome: A case report

RATIONALE

Opsoclonus-myoclonus syndrome (OMS) is a rare immune-mediated movement disorder, mostly of paraneoplastic or idiopathic origin. The disease usually has an acute onset, serious course and leads rapidly to disability in adult patients. To the best of our knowledge, this is the fourth presented case of OMS with a severe course and complete reversibility of neurological symptoms in a pregnant woman. This report includes videos and a literature review.

PATIENT CONCERNS

A 30-year-old woman in the 12th week of pregnancy developed severe nausea and vomiting, after several days balance and gait disorders appeared. On admission to hospital, neurological examination revealed opsoclonus, dysarthria, myoclonic jerks with ataxia of the trunk and limbs with inability to sit, stand or walk.

DIAGNOSIS

Well-known causes of OMS were excluded. Although in our patient the idiopathic origin of the disorder was taken under consideration, diagnosis of opsoclonus-myoclonus related to the pregnancy was highly likely.

INTERVENTIONS

After administration of steroids and benzodiazepines the patient improved.

OUTCOMES

In the 6th month of pregnancy, after termination of immunotherapy, she recovered completely and was able to sit, stand and walk independently. In the 39th week of pregnancy, she delivered a healthy child.

LESSONS

We confirm that understanding of clinical symptoms and rare causes of OMS contributes to early diagnosis and therapy, which ensures an optimal outcome. One probable cause of OMS could be a physiological change to immune system regulation during pregnancy. The relationship between OMS and pregnancy remains uncertain and needs further investigation.

Opsoclonus-myoclonus syndrome associated with anti Kelch-like protein-11 antibodies in a young female patient without cancer

Opsoclonus-myoclonus syndrome (OMS) is a rare neurological disorder. The pathogenesis is thought to be immune-mediated. In adults, it may be idiopathic or paraneoplastic in origin. However, most cases of paraneoplastic OMS in adults are not associated with well-characterized antibodies, except for a small subgroup who have anti-Ri antibodies. Herein, we provide the first detailed description of a case of OMS associated with a Kelch-like protein-11 antibody, a newly discovered biomarker for paraneoplastic neurological syndromes associated with germ-cell tumors. This was a young female patient in whom no tumor was ever detected and who had an excellent response to rituximab.

Opsoclonus myoclonus ataxia syndrome in severe acute respiratory syndrome coronavirus-2

A patient presented with an opsoclonus-myoclonus-ataxia syndrome after a 2-week period of fever. In her work as an assistant nurse, she had been exposed to patients infected with severe acute respiratory syndrome coronavirus-2. Laboratory investigations showed that the patient had positive IgG antibodies against this pathogen, and a chest CT showed changes compatible with this infection. Other known causes for this syndrome were excluded. Our case shows that the opsoclonus-myoclonus-ataxia syndrome can occur as a post-/para-infectious manifestation in patients infected with severe acute respiratory syndrome coronavirus-2.

Serum Biomarkers in Neuro-Ophthalmology: When to Test

Discovery and characterization of serologic biomarkers has revolutionized the diagnostic framework of systemic and paraneoplastic autoimmune neuro-ophthalmic diseases. Expanding recognition of the multiple ocular and visual manifestations of these conditions highlights the important role of the referring provider in identifying potential cases. Increasing ease of access to serologic testing also enables these practitioners to initiate the diagnostic work-up in suspected cases. We aimed to provide an update on the current knowledge surrounding and use of relevant autoimmune biomarkers by correlating specific clinical neuro-ophthalmic manifestations with autoantibody biomarkers. The utility of select biomarkers for myasthenia gravis, neuromyelitis optica spectrum disorder, myelin oligodendrocyte glycoprotein-IgG-associated disorder, opsoclonus-myoclonus syndrome, anti-collapsin-response mediator protein-5 optic neuropathy, and glial fibrillary acidic protein-IgG-associated disease are discussed with particular focus on the clinical contexts in which to consider testing.

Paraneoplastic neurological syndrome: an evolving story

Paraneoplastic neurological syndrome (PNS) comprises a group of neurological disorders that result from a misguided immune response to the nervous system triggered by a distant tumor. These disorders frequently manifest before the diagnosis of the underlying neoplasm. Since the first reported case in 1888 by Oppenheim, the knowledge in this area has evolved rapidly. Several classic PNS have been described, such as limbic encephalitis, paraneoplastic cerebellar degeneration, encephalomyelitis, opsoclonus-myoclonus, sensory neuronopathy, Lambert-Eaton Myasthenic syndrome, and chronic gastrointestinal dysmotility. It is now recognized that PNS can have varied nonclassical manifestations that extend beyond the traditional syndromic descriptions. Multiple onconeural antibodies with high specificity for certain tumor types and neurological phenotypes have been discovered over the past 3 decades. Increasing use of immune checkpoint inhibitors (ICIs) has led to increased recognition of neurologic ICI-related adverse events. Some of these resemble PNS. In this article, we review the clinical, oncologic, and immunopathogenic associations of PNS.

Opsoclonus-myoclonus syndrome, a post-infectious neurologic complication of COVID-19: case series and review of literature

Opsoclonus-myoclonus-ataxia syndrome is a heterogeneous constellation of symptoms ranging from full combination of these three neurological findings to varying degrees of isolated individual sign. Since the emergence of coronavirus disease 2019 (COVID-19), neurological symptoms, syndromes, and complications associated with this multi-organ viral infection have been reported and the various aspects of neurological involvement are increasingly uncovered. As a neuro-inflammatory disorder, one would expect to observe opsoclonus-myoclonus syndrome after a prevalent viral infection in a pandemic scale, as it has been the case for many other neuro-inflammatory syndromes. We report seven cases of opsoclonus-myoclonus syndrome presumably parainfectious in nature and discuss their phenomenology, their possible pathophysiological relationship to COVID-19, and diagnostic and treatment strategy in each case. Finally, we review the relevant data in the literature regarding the opsoclonus-myoclonus syndrome and possible similar cases associated with COVID-19 and its diagnostic importance for clinicians in various fields of medicine encountering COVID-19 patients and its complications.

Immune-Mediated Cerebellar Ataxias: Clinical Diagnosis and Treatment Based on Immunological and Physiological Mechanisms

Since the first description of immune-mediated cerebellar ataxias (IMCAs) by Charcot in 1868, several milestones have been reached in our understanding of this group of neurological disorders. IMCAs have diverse etiologies, such as gluten ataxia, postinfectious cerebellitis, paraneoplastic cerebellar degeneration, opsoclonus myoclonus syndrome, anti-GAD ataxia, and primary autoimmune cerebellar ataxia. The cerebellum, a vulnerable autoimmune target of the nervous system, has remarkable capacities (collectively known as the cerebellar reserve, closely linked to plasticity) to compensate and restore function following various pathological insults. Therefore, good prognosis is expected when immune-mediated therapeutic interventions are delivered during early stages when the cerebellar reserve can be preserved. However, some types of IMCAs show poor responses to immunotherapies, even if such therapies are introduced at an early stage. Thus, further research is needed to enhance our understanding of the autoimmune mechanisms underlying IMCAs, as such research could potentially lead to the development of more effective immunotherapies. We underscore the need to pursue the identification of robust biomarkers.

Paraneoplastic and autoimmune encephalitis: Alterations of mood and emotion

Autoimmune encephalitis often produces signs and symptoms that appear to be at the interface between neurology and psychiatry. Since psychiatric symptoms are often prominent, patients are often first seen in a psychiatric setting. Therefore it is important that psychiatrists, as well as neurologists, be able to recognize autoimmune encephalitis, a task that is often difficult. Early diagnosis of autoimmune encephalitis is crucial as this will usually result in a better outcome for the patient. This chapter provides an introduction to various autoimmune encephalitides and describes their pathophysiology and the possible associated neuropsychiatric, neuropsychological (cognitive), and neurological (sensory-motor) signs and symptoms. This chapter also reviews the possible treatments of these associated signs and symptoms.

Paraneoplastic Disorders of the Nervous System

PURPOSE OF REVIEW

This article reviews paraneoplastic neurologic disorders and includes an overview of the diagnostic approach, the role of autoantibody testing, the pathophysiology of these disorders, and treatment approaches. This article also provides an overview of the emerging clinical scenarios in which paraneoplastic and autoimmune neurologic disorders may occur.

RECENT FINDINGS

The number of autoantibodies associated with paraneoplastic neurologic disorders has rapidly expanded over the past 2 decades. These discoveries have improved our ability to diagnose patients with these disorders and have provided insight into their pathogenesis. It is now recognized that these antibodies can be broadly divided into two major categories based on the location of the target antigen: intracellular and cell surface/synaptic. Antibodies to intracellular antigens are almost always accompanied by cancer, respond less well to immunotherapy, and have an unfavorable outcome. In contrast, antibodies to cell surface or synaptic targets are less often accompanied by cancer, generally respond well to immunotherapy, and have a good prognosis. Paraneoplastic and autoimmune neurologic disorders are now being recognized in novel settings, including their occurrence as an immune-related adverse effect of immune checkpoint inhibitor treatment for cancer.

SUMMARY

This article discusses when to suspect a paraneoplastic neurologic syndrome, the diagnostic utility and pitfalls of neural autoantibody testing, how to best detect the underlying tumor, and the treatment approach that involves combinations of antineoplastic treatments, immunosuppressants, and supportive/symptomatic treatments.

Advances in Therapies of Cerebellar Disorders: Immune-mediated Ataxias

The identification of an increasing number of immune mediated ataxias suggests that the cerebellum is often a target organ for autoimmune insults. The diagnosis of immune mediated ataxias is challenging as there is significant clinical overlap between immune mediated and other forms of ataxia. Furthermore the classification of immune mediated ataxias requires further clarification particularly for those ataxias where no specific antigenic trigger and associated antibodies have been identified. Recognition of immune mediated ataxias remains imperative as therapeutic interventions can be effective, although given the relative rarity of this entity, large-scale treatment trials may not be feasible. This review will discuss advances in therapies for immune mediated ataxias based on what is currently available in the literature.

Paraneoplastic opsoclonus myoclonus syndrome associated with inflammatory myofibroblastic tumor in a pediatric patient

Opsoclonus myoclonus syndrome (OMS) is a rare neurological syndrome caused by a paraneoplastic autoimmune process that affects children with neuroblastic tumors. Treatment includes corticosteroids, intravenous gamma globulin (IVIG), rituximab, and other immunosuppressive therapies. Here, we describe a patient diagnosed with OMS associated with a localized inflammatory myofibroblastic tumor. The patient has no evidence of tumor recurrence following surgical resection with 8-month follow-up. The neurologic symptoms resolved with corticosteroids and IVIG. This case demonstrates that in children, neoplasms other than neuroblastoma may be associated with this paraneoplastic syndrome, and highlights the importance of evaluating patients with OMS for underlying malignancies.