Update on opsoclonus-myoclonus syndrome in adults

IAPRD new consensus classification of myoclonus

INTRODUCTION

Recent new advances in myoclonus characterization and etiology justify an update of the 40-year-old respected classification of myoclonus proposed by Marsden, Hallett, and Fahn. New advances include genetic studies and clinical neurophysiology characterization.

METHODS

The IAPRD appointed an expert panel to develop a new myoclonus classification. The Delphi Method of consensus determination was employed using a panel of fifteen international experts in myoclonus. In an in-person meeting, an Axis approach, previously used for dystonia and tremor was ratified by the panel: Axis I included clinical and neurophysiology features, Axis II included etiology categories. As a unique part of our Axis approach, Clinical Neurophysiology was included as Axis Ib. The first Delphi survey round queried agreement on major headings in Axes Ia and Ib, myoclonus clinical syndromes, and Axis II. In the second round, the full expert panel was surveyed on constituents and specific characteristics of each feature that had consensus in the first round.

RESULTS

In the first round, the percentage of agreement for the fifty-three out of the 56 items was greater than 60.0 %, indicating strong consensus among expert panel members. In the second round, for Axis Ia, Axis Ib, and Axis II, strong agreement was also achieved. For both rounds, Physiological Myoclonus had the lowest agreement. Comments from the whole panel were incorporated into the consensus results.

CONCLUSION

This Myoclonus Classification, which reached consensus using the Delphi Method, will facilitate a collaborative effort among myoclonus investigators to find better diagnostics and treatment for myoclonus patients.

Opsoclonus-Myoclonus-Ataxia Syndrome: A Rare Outcome Following Routine Vaccinations

Opsoclonus-myoclonus-ataxia syndrome (OMAS) is a rare neurological disorder, affecting approximately 0.18 per million individuals annually. It presents with a triad of opsoclonus, myoclonus, and ataxia, often including cognitive dysfunction and behavioral disturbances. Even though OMAS is non-fatal, it frequently follows a chronic-relapsing course, resulting in long-term neuropsychological sequelae in over 50% of patients. Diagnosis is challenging due to variable symptom presentation and the lack of specific diagnostic markers. We report a case of a two-month-old infant who developed OMAS after routine vaccinations, a rare post-vaccination occurrence. Initial treatment with high-dose corticosteroids successfully resolved symptoms, but the patient experienced a relapse during medication tapering. The relapse occurred following another vaccination, suggesting a potential link between the immune response triggered by vaccination and OMAS symptoms. Despite the early relapse, the patient had a favorable recovery, with normal neurodevelopment at 24 months and no further relapses. This case raises awareness of the rare autoimmune post-vaccine reaction as a possible etiology of OMAS, which is infrequently reported in the literature. With this report, we aimed to underscore the importance of early recognition of OMAS, particularly in infants, and highlight the potential for a positive outcome with timely diagnosis and treatment.

Exploring the Symptoms of and Insights Into Idiopathic Opsoclonus-Myoclonus-Ataxia Syndrome in Adults

Opsoclonus-myoclonus-ataxia syndrome (OMAS) is a rare immunological central nervous system disorder that mostly affects children, and it is extremely uncommon in adults. It usually presents idiopathically, as a parainfectious condition, or as a paraneoplastic syndrome. We present a case of a patient who developed adult-onset opsoclonus-myoclonus-ataxia syndrome (OMAS) without any associated infectious or neoplastic disease, a condition that is considered very rare in Central America. This study aimed to document a rare case of adult-onset opsoclonus-myoclonus-ataxia syndrome in a 39-year-old female, highlighting its atypical presentation and the diagnostic challenges involved. The patient presented with a one-week history of rapid-onset and progressive dizziness, nausea, and vomiting, associated with a two-day history of gait instability, memory loss, and sleep disturbances. Past medical history was only notable for psoriatic arthritis controlled with methotrexate. The neurologic examination revealed involuntary, rapid, multidirectional eye saccades consistent with opsoclonus, fast-twitching and jerking movements of the head and bilateral upper extremities consistent with myoclonus, and a wide-based gait with instability indicative of ataxia, suggesting a diagnosis of OMAS. There were no motor or sensory deficits, seizures, fever, or symptoms suggestive of infections. Brain magnetic resonance imaging and computed tomography scan of the head, neck, thorax, abdomen, and pelvis with and without contrast showed no abnormalities. Breast, abdomen, and gynecologic ultrasound, esophagogastroduodenoscopy, and colonoscopy showed no lesions suggestive of underlying neoplasia. Cerebrospinal fluid (CSF) analysis showed mild hyperproteinorrhachia and lymphocytic pleocytosis, along with oligoclonal bands. Viral, bacterial, and autoimmune encephalitis panels were negative. CSF bacterial, mycobacterial, and fungi cultures were negative. Serum viral serologies, tumor markers, and antineuronal antibodies were negative. The patient received treatment with plasmapheresis, intravenous immunoglobulin, and methylprednisolone, with significant but partial improvement of her symptoms.

Opsoclonus-myoclonus-ataxia syndrome associated with bacterial urinary tract infection

Opsoclonus-myoclonus-ataxia syndrome (OMAS) is a rare acquired neurological disorder characterized by opsoclonus, focal or diffuse myoclonus, truncal instability and associated other cerebellar signs and ataxia. While predominantly affecting children, it can rarely manifest in adults and could be associated with infections, paraneoplastic syndrome, drugs or other neurological disorders. We present a case of an elderly gentleman presenting with OMAS associated with a culture-positive urinary tract infection with Escherichia coli, successfully treated with antibiotics and immunoglobulins resulting in significant recovery.

Unique Magnetic Resonance Imaging Findings in Opsoclonus-Myoclonus Syndrome Secondary to the West Nile Virus

Opsoclonus-Myoclonus syndrome is a rare neurological disorder that presents with oculomotor dysfunction and is associated with immunological triggers such as an infection. We present a patient with Opsoclonus-Myoclonus syndrome secondary to a West Nile virus (WNV) infection and focus on a unique series of magnetic resonance imaging findings. The following is a case report based on experience taking care of the patient as a member of the primary team in the hospital, chart review, and imaging findings obtained and reported through the department of radiology. A 61-year-old male presented with fatigue, ataxia, dysarthria, and fever after a recent cabin visit in the summer. The initial workup ruled out meningitis and stroke. The patient's condition deteriorated despite empiric treatment. Repeat magnetic resonance imaging (MRI) revealed patchy fluid-attenuated inversion recovery (FLAIR) hyperintensities in the cerebellar hemispheres. Further evaluation confirmed West Nile virus infection through positive immunoglobulin M (IgM) and immunoglobulin G (IgG) antibodies. This case underscores the importance of neuroimaging in evaluating encephalopathy, especially in the presence of multiple comorbidities. These findings contribute to the broader knowledge of West Nile virus encephalitis.

Implications of Celiac Disease in Prospective Corneal Refractive Surgery Patients: A Narrative Review

Celiac disease (CeD) is a prevalent autoimmune disorder incited by gluten consumption, resulting in intestinal damage. Affecting approximately one in 133 people globally, CeD often remains undiagnosed due to its varied clinical presentations. The prevalence and diagnosis of CeD are influenced by several factors, including demographics and genetics, and it often coexists with other autoimmune diseases. Thus, the objective of this paper was to review the literature on ophthalmic manifestations of CeD and to create preliminary considerations for these patients wishing to undergo elective corneal refractive surgery (CRS). A literature review was conducted through July 2024, and relevant search terms were used to identify contributing papers. The review enabled the development of detailed considerations for the ocular manifestations of CeD and recommended management strategies for healthcare teams before and following CRS. The 24 papers included in this study illustrate that nutritional deficiencies and autoimmune concerns linked to CeD have distinctive ocular presentations. Based on these findings, patients with CeD may exhibit unconventional ocular manifestations beyond their typical gastrointestinal symptoms, such as decreased endothelial cell density (ECD), vitamin A deficiency leading to dryness, altered corneal nerve density, cataracts, uveitis, changes in choroidal thickness, papilledema, and neurological issues such as nystagmus. Patients with CeD may also experience synergistic impacts from concomitant autoimmune conditions such as Type 1 Diabetes Mellitus (T1DM) in addition to the coexistence of thyroid ophthalmopathy. Recognizing that CeD is an autoimmune disorder that can be exacerbated by other conditions, it is essential to conduct a thorough evaluation for elective CRS. Due to the variability in ocular manifestations among CeD patients, individualized evaluations are crucial for determining surgical candidacy and optimizing outcomes, especially for patients who may not be well controlled. Evaluations are likely to encompass a subjective assessment through a questionnaire exploring the patient's past medical history related to CeD. These questions can range from inquiring about general past medical history related to CeD regarding dietary gluten intake and weight loss to joint pain and cognitive impairments such as brain fog. Clinicians should also perform a comprehensive objective assessment utilizing slit-lamp biomicroscopy, Schirmer test, tear break-up time (TBUT), optical coherence tomography (OCT), Scheimpflug imaging, or fundoscopy. Although there is currently no specific information regarding CRS recommendations for patients with CeD, we believe the considerations outlined in this paper should serve as preliminary guidelines for clinicians. While our findings have formed considerations for future healthcare teams, further research is needed to fully understand the impact of CeD on CRS outcomes and refine these recommendations.

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.

Drug- and Toxin-Induced Opsoclonus - a Systematized Review, including a Case Report on Amantadine-Induced Opsoclonus in Multiple System Atrophy

Background

Opsoclonus is a rare disorder characterized by conjugate multidirectional, horizontal, vertical, and torsional saccadic oscillations, without intersaccadic interval, resulting from dysfunction within complex neuronal pathways in the brainstem and cerebellum. While most cases of opsoclonus are associated with autoimmune or paraneoplastic disorders, infectious agents, trauma, or remain idiopathic, opsoclonus can also be caused by medications affecting neurotransmission. This review was prompted by a case of opsoclonus occurring in a patient with Multiple System Atrophy, where amantadine, an NMDA-receptor antagonist, appeared to induce opsoclonus.

Methods

Case report of a single patient and systematized review of toxic/drug-induced opsoclonus, selecting articles based on predefined criteria and assessing the quality of included studies.

Results

The review included 30 articles encompassing 158 cases of toxic/drug-induced opsoclonus. 74% of cases were attributed to bark scorpion poisoning, followed by 9% of cases associated with chlordecone intoxication. The remaining cases were due to various toxics/drugs, highlighting the involvement of various neurotransmitters, including acetylcholine, glutamate, GABA, dopamine, glycine, and sodium channels, in the development of opsoclonus.

Conclusion

Toxic/drug-induced opsoclonus is very rare. The diversity of toxics/drugs impacting different neurotransmitter systems makes it challenging to define a unifying mechanism, given the intricate neuronal pathways underlying eye movement physiology and opsoclonus pathophysiology.

Opsoclonus-Myoclonus With Anti-YO Antibodies Revealing Breast Cancer: A Case Report

Opsoclonus myoclonus syndrome (OMS) is a rare neurological disorder characterized by irregular, continuous, and chaotic eye saccades accompanied by myoclonus, defined by brief, shock-like muscle spasms in the arms or legs. This syndrome often presents with additional features such as cerebellar syndrome, nycthemeral rhythm disorders, hallucinosis, and irritability-type behavioral disorders. In adults, OMS is predominantly paraneoplastic, necessitating screening for onconeural antibodies (ONA). While specific medications for OMS are lacking, addressing the underlying cause may ameliorate its clinical manifestations. The presence of opsoclonus-myoclonus should prompt urgent and thorough investigation for an underlying cancer, given its frequent association with paraneoplastic neurological syndrome (PNS). Here, we present the case of a 39-year-old patient with opsoclonus associated with cerebellar ataxia, revealing a breast neoplasm with positive anti-YO antibodies. Through the review of the literature, we discuss the epidemiological, clinical, diagnostic, and therapeutic aspects of this rare situation.

Brain Volumes in Opsoclonus-Myoclonus Ataxia Syndrome: A Longitudinal Study

INTRODUCTION

Little is known about the longitudinal trajectory of brain growth in children with opsoclonus-myoclonus ataxia syndrome. We performed a longitudinal evaluation of brain volumes in pediatric opsoclonus-myoclonus ataxia syndrome patients compared with age- and sex-matched healthy children.

PATIENTS AND METHODS

This longitudinal case-control study included brain magnetic resonance imaging (MRI) scans from consecutive pediatric opsoclonus-myoclonus ataxia syndrome patients (2009-2020) and age- and sex-matched healthy control children. FreeSurfer analysis provided automatic volumetry of the brain. Paired t tests were performed on the curvature of growth trajectories, with Bonferroni correction.

RESULTS

A total of 14 opsoclonus-myoclonus ataxia syndrome patients (12 female) and 474 healthy control children (406 female) were included. Curvature of the growth trajectories of the cerebral white and gray matter, cerebellar white and gray matter, and brainstem differed significantly between opsoclonus-myoclonus ataxia syndrome patients and healthy control children (cerebral white matter, P = .01; cerebral gray matter, P = .01; cerebellar white matter, P < .001; cerebellar gray matter, P = .049; brainstem, P < .01).

DISCUSSION/CONCLUSION

We found abnormal brain maturation in the supratentorial brain, brainstem, and cerebellum in children with opsoclonus-myoclonus ataxia syndrome.

Paraneoplastic Cerebellar Degeneration Associated with Breast Cancer: A Case Report and a Narrative Review

Paraneoplastic neurological syndromes (PNSs) are an uncommon complication of cancer, affecting nearby 1/10,000 subjects with a tumour. PNSs can involve all the central and peripheral nervous systems, the muscular system, and the neuromuscular junction, causing extremely variable symptomatology. The diagnosis of the paraneoplastic disease usually precedes the clinical manifestations of cancer, making an immediate recognition of the pathology crucial to obtain a better prognosis. PNSs are autoimmune diseases caused by the expression of common antigens by the tumour and the nervous system. Specific antibodies can help clinicians diagnose them, but unfortunately, they are not always detectable. Immunosuppressive therapy and the treatment of cancer are the cornerstones of therapy for PNSs. This paper reports a case of PNSs associated with breast tumours and focuses on the most common paraneoplastic neurological syndromes. We report a case of a young female with a clinical syndrome of the occurrence of rigidity in the right lower limb with postural instability with walking supported and diplopia, with a final diagnosis of paraneoplastic cerebellar degeneration and seronegative rigid human syndrome associated with infiltrating ductal carcinoma of the breast.

Paraneoplastic cerebellar and brainstem disorders

Paraneoplastic cerebellar and brainstem disorders are a heterogeneous group that requires prompt recognition and treatment to help prevent irreversible neurologic injury. Paraneoplastic cerebellar degeneration is best characterized by Yo antibodies in patients with breast or ovarian cancer. Tr (DNER) antibodies in patients with Hodgkin lymphoma can also present with a pure cerebellar syndrome and is one of the few paraneoplastic syndromes found with hematological malignancy. Opsoclonus-myoclonus-ataxia syndrome presents in both pediatric and adult patients with characteristic clinical findings. Other paraneoplastic brainstem syndromes are associated with Ma2 and Hu antibodies, which can cause widespread neurologic dysfunction. The differential for these disorders is broad and also includes pharmacological side effects, infection or postinfectious processes, and neurodegenerative diseases. Although these immune-mediated disorders have been known for many years, mechanisms of pathogenesis are still unclear, and optimal treatment has not been established.

[Opsoclonus-myoclonus syndrome associated with West Nile virus]

Opsoclonus is oculomotor dyskinesia characterized by rapid, repetitive conjugate eye movements that are involuntary, arrhythmic, chaotic, and multidirectional (horizontal, vertical, and torsional components). Most common cause of the symptom is paraneoplastic process. It is combined with myoclonus usually with the development of opsoclonus-myoclonus syndrome. Viral etiology is one of the possible causes of the of this syndrome, which is presented in the following case. A 26-year-old man was admitted to an infectious hospital suspected by encephalitis. After a 2-day febrile fever the patient developed balance problem, nausea, vomiting, tremors in the limbs and head, sensations of jerking of eyeballs. The neurological examination revealed opsoclonus, myoclonic jerking in the limbs, neck and trunk muscles, severe static and dynamic ataxia, there was no consciousness changes or altered mental stature. Cerebrospinal fluid examination revealed a pleocytosis (24 cells), increased protein levels (1.1 g/l). MRI of the brain was normal. After excluding of typical neuroinfections the patient was tested for West Nile fever. Elevated titers of IgG and IgM for West Nile fever virus were detected, as well as positive PCR for virus RNA in the cerebrospinal fluid. Patient was treated by acyclovir, an antibiotic and dexamethasone but severe neurological symptoms were persisted for 2 weeks with inability of sitting and walking. Then the symptoms gradually began to improve, rehabilitation was included with total recovery during the next 2 months. The doctors should be aware for possibility of neuroinvasive form of West Nile fever as the etiology of opsoclonus-myoclonus syndrome.

Paraneoplastic orbital myositis as a first manifestation of renal cell carcinoma

Paraneoplastic syndromes (PNSs) are remote effects of the primary tumor on tissues and organs, not related to direct invasion or metastasis. Ophthalmological involvement has been reported in 0.01-0.1% cases of PNSs. It may present as retinopathy, optic neuritis, myasthenia-like syndromes, or orbital myositis (OM), among others. An 89-year-old male with bilateral ocular pain and chemosis, was given an initial diagnosis of bilateral acute conjunctivitis. After 5 days, the patient presented worsening of the pain and bilateral complete ophthalmoplegia. Cranial CT scan showed diffuse bilateral thickening of the four rectus muscles. Inflammatory markers, thyroid hormones, and thyroid antibodies were normal. An abdominal ultrasound test was performed, observing a mass in the right kidney. After confirmation of the lesion with a CT scan, the radiological characteristics of the lesion were highly suggestive of renal cell carcinoma. Treatment with intravenous corticosteroids was ensued with complete resolution of all ophthalmological symptoms. Paraneoplastic orbital panmyositis was first described in 1994. Since then it has been reported scarcely, remaining an extremely rare entity. To our knowledge, this is the first report of its association with renal cell carcinoma. In the absence of inflammatory or dysthyroid blood markers, bilateral orbital panmyositis warrants further investigation for a possible underlying oncological pathology.

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.

Opsoclonus myoclonus ataxia syndrome, ovarian teratoma and anti-NMDAR antibody: an 'unresolved' mystery

Background

Opsoclonus-myoclonus-ataxia syndrome (OMAS) is characterised by the combination of opsoclonus and arrhythmic action myoclonus with axial ataxia and dysarthria. In adults, a majority are paraneoplastic secondary to solid organ tumours and could harbour antibodies against intracellular epitopes; however, certain proportions have detectable antibodies to various neuronal cell surface antigens. Anti-N-methyl-D-aspartate (NMDAR) antibodies and ovarian teratomas have been implicated in OMAS.

Methods

Report of two cases and review of literature.

Results

Two middle-aged women presented with subacute-onset, rapidly progressive OMAS and behavioural changes consistent with psychosis. The first patient had detectable antibodies to NMDAR in the cerebrospinal fluid (CSF) alone. Evaluation for ovarian teratoma was negative. The second patient had no detectable antibodies in serum or CSF; however, she had an underlying ovarian teratoma. Patient A was treated with pulse steroids, therapeutic plasma exchange (TPE) followed by bortezomib (BOR) and dexamethasone, while patient B was treated with steroids, TPE followed by surgical resection of ovarian teratoma. Both patients had favourable outcomes and were asymptomatic at the 6 monthly follow-up.

Conclusions

With coexistent neuropsychiatric manifestations, OMAS can be considered a distinct entity of autoimmune encephalitis, pathogenesis being immune activation against known/unknown neuronal cell surface antigens. The observation of absence of anti-NMDAR antibody in patients with teratoma-associated OMAS and vice versa is intriguing. Further research on the potential role of ovarian teratoma in evoking neuronal autoimmunity and its targets is required. The management challenge in both cases including the potential use of BOR has been highlighted.

Cerebrospinal Fluid Anti-Neuronal Autoantibodies in COVID-19-Associated Limbic Encephalitis with Acute Cerebellar Ataxia and Myoclonus Syndrome: Case Report and Literature Review

Since the outbreak of coronavirus (COVID-19) in 2019, various rare movement disorders and cognitive changes have been recognized as potential neurological complications. The early treatment of some of these allows rapid recovery; therefore, we must diagnose these manifestations in a timely way. We describe the case of a 76-year-old man infected with severe acute respiratory syndrome coronavirus-2 who presented with confusion and hallucinations and was admitted to our hospital 14 days after the onset of symptoms. One day later, he developed generalized myoclonus, dysarthria and ataxia, and tonic clonic seizures and was admitted to the intensive care unit. A diagnosis of COVID-19-associated autoimmune encephalitis with characteristics of limbic encephalitis and immune-mediated acute cerebellar ataxia and myoclonus syndrome was supported by alterations in the limbic system shown in magnetic resonance imaging, lateralized discharges shown in electroencephalography, a slightly elevated protein level in the cerebrospinal fluid (CSF), and indirect immunofluorescence in the CSF with autoantibody binding to anatomical structures of the cerebellum and hippocampus. The patient improved with 2 weeks of corticosteroid treatment and four sessions of plasmapheresis. Our current case study describes a rare case of COVID-19-related limbic encephalitis with immune-mediated acute cerebellar ataxia and myoclonus syndrome (ACAM syndrome) and strengthens the need for tissue-based assays (TBAs) to screen the serum and/or CSF of patients highly suspected to have autoimmune encephalitis. We believe that the timely diagnosis and targeted aggressive immunotherapy were mainly responsible for the patient's total recovery.

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.

Paraneoplastic Neurological Syndromes of the Central Nervous System: Pathophysiology, Diagnosis, and Treatment

Paraneoplastic neurological syndromes (PNS) include any symptomatic and non-metastatic neurological manifestations associated with a neoplasm. PNS associated with antibodies against intracellular antigens, known as "high-risk" antibodies, show frequent association with underlying cancer. PNS associated with antibodies against neural surface antigens, known as "intermediate- or low-risk" antibodies, are less frequently associated with cancer. In this narrative review, we will focus on PNS of the central nervous system (CNS). Clinicians should have a high index of suspicion with acute/subacute encephalopathies to achieve a prompt diagnosis and treatment. PNS of the CNS exhibit a range of overlapping "high-risk" clinical syndromes, including but not limited to latent and overt rapidly progressive cerebellar syndrome, opsoclonus-myoclonus-ataxia syndrome, paraneoplastic (and limbic) encephalitis/encephalomyelitis, and stiff-person spectrum disorders. Some of these phenotypes may also arise from recent anti-cancer treatments, namely immune-checkpoint inhibitors and CAR T-cell therapies, as a consequence of boosting of the immune system against cancer cells. Here, we highlight the clinical features of PNS of the CNS, their associated tumors and antibodies, and the diagnostic and therapeutic strategies. The potential and the advance of this review consists on a broad description on how the field of PNS of the CNS is constantly expanding with newly discovered antibodies and syndromes. Standardized diagnostic criteria and disease biomarkers are fundamental to quickly recognize PNS to allow prompt treatment initiation, thus improving the long-term outcome of these conditions.

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.

Opsoclonus Myoclonus Ataxia Syndrome Due to SARS-CoV-2

Opsoclonus myoclonus syndrome (OMS)/opsoclonus myoclonus ataxia syndrome (OMAS), also known as Kinsbourne's syndrome or 'dancing eyes-dancing feet' syndrome, is a rare central nervous system manifestation of COVID-19 but an increasing number of articles have reported patients in whom COVID-19 was complicated by OMS/OMAS. This narrative review aims at summarising and discussing current knowledge about the clinical presentation, diagnosis, treatment and outcome of SARS-CoV-2 associated OMS/OMAS. Altogether, 29 articles reporting 45 patients with SARS-CoV-2 associated OMS/OMAS were retrieved. Their ages ranged from 2 to 88 years. Three patients were children and the remainder adults. Gender was male in 32 patients and female in 13 patients. Opsoclonus was described in 29 patients, which was associated with myoclonus in 28 cases. Myoclonus was described in 43 patients, which was associated with opsoclonus and ataxia in 18 patients. Cerebral magnetic resonance imaging and cerebrospinal fluid investigations were not informative in the majority of the cases. OMS/OMAS was treated with steroids in 28 patients and with intravenous immunoglobulin (IVIG) in 15 patients. Clonazepam was given to 18 patients, levetiracetam to 13 patients, and sodium valproate to eight patients. Complete recovery was achieved in 12 cases and incomplete recovery in 22 cases. Diagnosing SARS-CoV-2 associated OMS/OMAS requires extensive neurological work up and exclusion of various differentials. SARS-CoV-2 associated OMS/OMAS may not always present with the full spectrum of manifestations but as an abortive syndrome. OMS/OMAS should not be missed as it usually responds favourably to steroids or IVIG.

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.

Paraneoplastic Syndromes in Neuro-Ophthalmology

Paraneoplastic neurological syndromes (PNS) occur in about 1 in 300 cases of cancer. The usual mechanism is that an antigen on the cancer sets off an immune response that then cross-reacts with a nervous system antigen. The presentation is usually with a subacute progressive neurological disorder. The management of these conditions is usually of both the underlying tumor and immunomodulation to suppress the autoimmune response. There are a number of these conditions that can present to the Neuro-Ophthalmology clinic, either as a discrete condition affecting vision or eye movements or as part of a more widespread neurological disorder. This article will discuss these conditions, their management and prognosis.

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.

Paraneoplastic syndrome in neuroophthalmology

Paraneoplastic syndrome is a group of clinical symptoms that occur in the state of systemic malignant tumors. Paraneoplastic syndrome of the nervous system can affect any part of the central and peripheral nervous system and may also affect the eyes. In neuroophthalmology, paraneoplastic syndrome has a variety of manifestations that can affect both the afferent and efferent visual systems. The afferent system may involve the optic nerve, retina and uvea; the efferent system may involve eye movement, neuromuscular joints or involuntary eye movements and pupil abnormalities and may also have other neurological symptoms outside the visual system. This article discusses the clinical manifestations, pathological mechanisms, detection methods and treatment methods of paraneoplastic syndrome in neuroophthalmology. The performance of paraneoplastic syndrome is diverse, the diagnosis is difficult, and the treatment should be considered systematically. Differential diagnosis, optimal evaluation and management of these manifestations is not only the key to treatment but also a challenge.

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.

Paraneoplastic syndromes in ophthalmology

Paraneoplastic syndromes consist on systemic manifestations associated with certain cancers which are not a direct consequence of tumor invasion or its metastases. It is known that autoimmunity and autoantibody synthesis play an important role in its pathophysiology due to a process of molecular mimicry. Paraneoplastic syndromes in ophthalmology are rare, but it is important to recognize them clinically because in some cases symptoms preceded the diagnosis of an underlying neoplasia. Most frequently involved cancer is small cell lung carcinoma, but there is also a relationship with other tumor etiologies such as thymoma, gynecological tumors or neuroblastoma in children. Paraneoplastic syndromes with ocular involvement can be divided into those that affect the afferent visual pathway, such as cancer-associated retinopathy, melanoma-associated retinopathy, or paraneoplastic optic neuropathy; and the ones that affect the efferent visual pathway, such as bilateral tonic pupils, Myasthenia Gravis, Lambert-Eaton syndrome or paraneoplastic cerebellar degeneration. The presence of autoantibodies is helpful in clinical practice but negativity does not exclude this diagnosis. Although evolution and prognosis is linked to primary disease, in some cases specific treatment, usually immunosuppressive therapy, can help improving patients quality of life.

CRB1-associated retinal dystrophy presenting as self-resolving opsoclonus and posterior uveitis

Purpose

To describe the unusual case of inflammatory CRB1-associated retinal dystrophy that initially presented with self-resolving opsoclonus.

Observations

We report the case of a now 2-year-old female who developed opsoclonus without myoclonus at the age of 4 months. An extensive workup for neuroblastoma and other systemic diseases was unremarkable, and all unusual eye movements self-resolved at age 10 months. Twenty-one months after initial presentation, she began having reduced visual behaviors, and comprehensive ophthalmic exam at that time revealed recurrent saccadic intrusions as well as severe, chronic retinal inflammation and dystrophic changes. An extensive infectious and inflammatory workup was negative. Genetic sequencing revealed two variants in CRB1: a heterozygous missense mutation and a heterozygous novel deletion involving exon 12. The patient was treated with monthly infliximab and methylprednisolone infusions with improvement in her optic disc and macular capillary leakage. The patient's 8-month-old sister also harbored the same variants in CRB1 and had early signs of retinal dystrophy and peripheral vascular leakage on exam.

Conclusion

Saccadic intrusions may be the first sign of a retinal dystrophy, and infants and children with this presentation should undergo a complete eye exam. We further highlight the link between CRB1-associated retinal dystrophy and inflammation, and how systemic steroids and tumor necrosis factor alpha (TNF-α) inhibitors may be effective therapies. Finally, we report a novel deletion in CRB1 that is likely highly penetrant.

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.

Temporal Changes in Brain Perfusion in a Patient with Myoclonus and Ataxia Syndrome Associated with COVID-19

Myoclonus and ataxia, with or without opsoclonus, have recently been recognized as a central nervous system syndrome associated with coronavirus disease-2019 (COVID-19). A 52-year-old Japanese man developed myoclonus and ataxia 16 days after the onset of COVID-19. Brain single-photon emission computed tomography (SPECT) revealed hyperperfusion in the cerebellum and hypoperfusion in the cerebral cortices with frontal predominance during the acute stage, which improved over two months. This study indicates that brain perfusion SPECT can be effective in detecting functional alterations in COVID-19-related myoclonus and ataxia.

Neurological toll of COVID-19

The first case of coronavirus illness was discovered in Wuhan, China, in January 2020 and quickly spread worldwide within the next couple of months. The condition was initially only linked with respiratory disorders. After the evolution of various variants of the SARS-CoV-2, the critical impact of the virus spread to multiple organs and soon, neurological disorder manifestations started to appear in the infected patients. The review is focused on the manifestation of various neurological disorders linked with both the central nervous system and peripheral nervous system. Disorders such as cytokine release syndrome, encephalitis, acute stroke, and Bell's palsy are given specific attention and psychological manifestations are also investigated. For a clear conclusion, cognitive impairment, drug addiction disorders, mood and anxiety disorders, and post-traumatic stress disorder are all fully examined. The association of the SARS-CoV-2 with neurological disorders and pathway is yet to be clear. For better understanding, the explanation of the possible mechanism of viral infection influencing the nervous system is also attempted in the review. While several vaccines and drugs are already involved in treating the SARS-CoV-2 condition, the disease is still considered fatal and more likely to leave permanent neurological damage, which leads to an essential requirement for more research to explore the neurological toll of the COVID-19 disease.

An unusual occurrence of opsoclonus and liver enzymes elevation in a patient with acute motor and sensory axonal neuropathy subtype of Guillain-Barré syndrome

Background

Acute motor and sensory axonal neuropathy (AMSAN) is a subtype of Guillain-Barré syndrome (GBS) differentiated by nerve conduction studies (NCS) and characterized by symmetric ascending paralysis often involving respiratory muscles. While opsoclonus, which is involuntary chaotic rapid eye movements, is not a common manifestation of GBS. Moreover, little published data are available on the relation between liver enzymes elevation and GBS.

Case presentation

A 42-year-old man presented to Al Mouwassat University Hospital with weakness in all limbs and dyspnea. Examination showed an elevated respiratory rate, hyporeflexia, and decreased strength of upper and lower limbs. Analysis of cerebrospinal fluid revealed an albuminocyto-dissociation suggesting the diagnosis of GBS and subsequent plasmapheresis. NCS confirmed a diagnosis of AMSAN. Elevation in liver enzymes was noticed prompting further exploration with no positive findings. Despite treatment efforts, the patient developed severe dyspnea, deterioration in cognitive abilities, and opsoclonus with a normal brain MRI. Unfortunately, he developed respiratory failure which lead to his death.

Conclusion

In this case, we highlight the occurrence of opsoclonus which is a rarely-encountered manifestation of GBS, in addition to an unexplained elevated liver enzyme, the thing that could contribute to larger research to further comprehend the pathophysiology of GBS.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12883-022-02599-0.

Delayed Opsoclonus-Myoclonus Syndrome After Ovarian Teratoma Resection

ABSTRACT

Opsoclonus-myoclonus syndrome (OMS) is a rare syndrome characterized by opsoclonus, which is irregular, spontaneous, multivectorial saccadic eye movements, along with diffuse or focal myoclonus and sometimes ataxia. OMS is associated with paraneoplastic etiologies in 20%-40% of cases, with small-cell lung and breast cancers the most common associated primary neoplasms in adults, whereas neuroblastoma is more common in children and ovarian teratoma may occur in women younger than 30 years. Onconeural antibodies are often not identified. In existing literature, paraneoplastic OMS precedes identification of the neoplasm, and neurological recovery depends on treatment of the underlying cancer. We describe a 27-year-old woman with the delayed onset of OMS one month after resection of ovarian teratoma, likely due to immune trigger from antigen exposure at the time of resection. She was treated with intravenous methylprednisolone, immunoglobulins, and eventually rituximab with resolution of her symptoms. Identification of OMS after tumor resection and prompt immunotherapy are critical for neurologic recovery. At 30-month follow-up, this patient had not experienced recurrence of OMS.

Surgical considerations for neuroblastoma-associated opsoclonus-myoclonus-ataxia syndrome: a series of 14 patients from a single institution

INTRODUCTION

Neuroblastoma is a childhood cancer of neural crest cells occasionally associated with opsoclonus-myoclonus-ataxia syndrome (OMAS), a paraneoplastic process characterized by ataxia, rapid eye movements, and muscle twitching. OMAS treatment and outcomes are well studied, but prior reports do not detail how the presence of OMAS should impact surgical approach, particularly for tumors with image defined risk factors (IDRF).

METHODS

We reviewed patients with neuroblastoma and OMAS at our institution from January 2009 to December 2020 and recorded tumor characteristics, operative details, OMAS therapies, and outcomes.

RESULTS

We identified 14 patients with neuroblastoma and OMAS out of 212 patients referred for surgery. There were 11 gross total resections and three partial resections. Two patients with partial resections developed OMAS after initial resection. One patient with gross total resection developed tumor recurrence 10 years later with OMAS redevelopment signaling recurrence. Three patients were positive for IDRFs and the one receiving neoadjuvant therapy achieved a gross total resection.

CONCLUSIONS

OMAS development after partial resection and OMAS recurrence following tumor recurrence indicates a correlation between tumor bulk and the paraneoplastic process. This justifies an aggressive resection even for low-risk tumors. Neoadjuvant therapy should be considered for potentially unresectable tumors with image defined risk factors.

LEVEL OF EVIDENCE

IV.

[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.

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.

[Paraneoplastic ophthalmopathies]

Ocular paraneoplastic syndromes are rare conditions that can affect any part of the eye at any age. Thus, every ophthalmologist should be familiar with their management, as some of them may reveal severe, life-threatening conditions. These consist overwhelmingly of neuro-ophthalmological manifestations, affecting the optic nerve (paraneoplastic optic neuritis), retina (paraneoplastic retinopathy) or neurological pathways generating eye movements (saccadic intrusion, oculomotor palsy, nystagmus...); occasionally, they involve the anterior segment, orbit or uveal tract. As some of these manifestations appear to be quite common and non-specific, any systemic or especially neurologic comorbidities should increase suspicion. Treatment relies first on oncologic management, and then often more targeted therapy for the associated immune involvement.

Opsoclonus-Myoclonus-Ataxia Syndrome Related to the Novel Coronavirus (COVID-19)

Supplemental Digital Content is Available in the Text.

De Novo Movement Disorders and COVID-19: Exploring the Interface

Background

Neurological manifestations of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are being widely documented. However, movement disorders in the setting of 2019 coronavirus infectious disease (COVID-19) have been a strikingly less discussed topic.

Objectives

To summarize available pieces of evidence documenting de novo movement disorders in COVID-19.

Methods

We used the existing PRISMA consensus statement. Data were collected from PubMed, EMBASE, Web of Science, and Scopus databases up to the 29th January, 2021, using pre-specified searching strategies.

Results

Twenty-two articles were selected for the qualitative synthesis. Among these, a total of 52 patients with de novo movement disorders were reported. Most of these had myoclonus, ataxia, tremor or a combination of these, while three had parkinsonism and one a functional disorder. In general, they were managed successfully by intravenous immunoglobulin or steroids. Some cases, primarily with myoclonus, could be ascribed to medication exposures, metabolic disturbances or severe hypoxia, meanwhile others to a post-or para-infectious immune-mediated mechanism. SARS-CoV-2 could also invade the central nervous system, through vascular or retrograde axonal pathways, and cause movement disorders by two primary mechanisms. Firstly, through the downregulation of angiotensin-converting enzyme 2 receptors, resulting in the imbalance of dopamine and norepinephrine; and secondly, the virus could cause cellular vacuolation, demyelination and gliosis, leading to encephalitis and associated movement disorders.

Conclusion

De novo movement disorders are scantly reported in COVID-19. The links between SARS-CoV-2 and movement disorders are not yet established. However, we should closely monitor COVID-19 survivors for the possibility of post-COVID movement disorders.