Opsoclonus-Myoclonus Syndrome in Children and Adolescents: A Therapeutic Challenge

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.

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 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.

Acute Cerebellar Inflammation and Related Ataxia: Mechanisms and Pathophysiology

The cerebellum governs motor coordination and motor learning. Infection with external microorganisms, such as viruses, bacteria, and fungi, induces the release and production of inflammatory mediators, which drive acute cerebellar inflammation. The clinical observation of acute cerebellitis is associated with the emergence of cerebellar ataxia. In our animal model of the acute inflammation of the cerebellar cortex, animals did not show any ataxia but hyperexcitability in the cerebellar cortex and depression-like behaviors. In contrast, animal models with neurodegeneration of the cerebellar Purkinje cells and hypoexcitability of the neurons show cerebellar ataxia. The suppression of the Ca2+-activated K+ channels in vivo is associated with a type of ataxia. Therefore, there is a gap in our interpretation between the very early phase of cerebellar inflammation and the emergence of cerebellar ataxia. In this review, we discuss the hypothesized scenario concerning the emergence of cerebellar ataxia. First, compared with genetically induced cerebellar ataxias, we introduce infection and inflammation in the cerebellum via aberrant immunity and glial responses. Especially, we focus on infections with cytomegalovirus, influenza virus, dengue virus, and SARS-CoV-2, potential relevance to mitochondrial DNA, and autoimmunity in infection. Second, we review neurophysiological modulation (intrinsic excitability, excitatory, and inhibitory synaptic transmission) by inflammatory mediators and aberrant immunity. Next, we discuss the cerebellar circuit dysfunction (presumably, via maintaining the homeostatic property). Lastly, we propose the mechanism of the cerebellar ataxia and possible treatments for the ataxia in the cerebellar inflammation.