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Internal Medicine

Opsoclonus-myoclonus syndrome (OMS)

Introduction

Opsoclonus-myoclonus-ataxia syndrome (OMAS/OMS) Autoimmune neurological disorder characterised by rapid multidirectional conjugate eye movements (opsoclonus), myoclonus and ataxia, along with behavioural changes in adults and irritability in children.

  • “Dancing eyes, dancing feet syndrome”

Epidemiology

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(A) Frequency of opsoclonus-myoclonus syndrome (OMS) by age of OMS onset. N = 389. Data are displayed at 0.25-year increments. (B) Frequency of various neuroblastic tumors by OMS onset age. N = 177. Abbreviations—NB, neuroblastoma; GNB, ganglioneuroblastoma; GN, ganglioneuroma. (C) Frequency of neuroblastoma INSS stages by OMS onset age. N = 118. Classification—Stage 1: localized unilateral tumor, negative lymph nodes outside tumor; Stage 2: not all visible tumor could be resected but negative lymph nodes outside tumor (2A) or positive ipsilateral nodes (2B); Stage 3: not completely resected, tumor crossed midline, or positive contralateral lymph nodes, or tumor midline and spread to both sides; Stage 4: metastatic; Stage 4S: metastatic in infants <1 years old, unilateral tumor, no contralateral positive nodes (<10% marrow cells positive). (D) Frequency of neuroblastoma without OMS from published statistics (3). N = 643. Visual comparison of (C,D) reveals that the frequency of paraneoplastic OMS and of neuroblastoma is not a mere function of each other. | Pranzatelli, M. R., Tate, E. D., & McGee, N. R. (2017). Demographic, Clinical, and Immunologic Features of 389 Children with Opsoclonus-Myoclonus Syndrome: A Cross-sectional Study . Frontiers in Neurology . Retrieved from https://www.frontiersin.org/article/10.3389/fneur.2017.00468

Aetiology

  • Common variants:
    • Idiopathic OMS (I-OMS)
  • Parainfectious
  • Paraneoplastic OMS (P-OMS)
    • Children: Neuroblastoma (almost exclusively)
    • Adults: Small cell lung cancer & breast cancer

 

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Box plot showing distribution of age at onset of symptoms (months) and time to onset of opsoclonus after initial onset of initial symptom (weeks) in tumor versus nontumor group | Muthusamy K, Thomas M, Yoganathan S, Sudhakar SV. Clinical profile, prognostic indicators, and therapeutic outcomes of pediatric opsoclonus-myoclonus-ataxia syndrome: A single-center experience from South India. Ann Indian Acad Neurol 2019;22:295-301

Clinical features

Prodromal symptoms:

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Prodromal symptoms in patients with opsoclonus-myoclonus syndrome (OMS) per history. Patients may have more than one prodromal symptom. |

Symptoms:

  • OpsoclonusConjugated involuntary rapid eye movements in all directions.
  • MyoclonusSudden, quick jerks of a muscle or muscle group
  • Developmental delay
  • Extreme irritability
  • Severe sleep disturbances
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Ten presenting neurological signs of opsoclonus-myoclonus syndrome (OMS) by order of appearance per parents. The data are median ranks with interquartile range: the lower the rank, the earlier the sign. In Dunn’s multiple comparisons test, staggering occurred significantly before other signs (P < 0.0001). Refusing to walk and inability to sit were similar in occurring significantly later than falling, body jerks, and irritability, but earlier than loss of speech. Falling and body jerks occurred earlier than loss of speech or drooling. Loss of speech and drooling occurred later than irritability. | Pranzatelli, M. R., Tate, E. D., & McGee, N. R. (2017). Demographic, Clinical, and Immunologic Features of 389 Children with Opsoclonus-Myoclonus Syndrome: A Cross-sectional Study . Frontiers in Neurology . Retrieved from https://www.frontiersin.org/article/10.3389/fneur.2017.00468

Cerebellar signs:

  • Dyspraxia (difficulty in coordination and movement)
  • Dysarthria (motor speech disorder)
  • Dysphagia (difficulty swallowing)
  • Hypotonia, lethargy, and malaise

Case studies:


Diagnosis

Diagnostic criteria:

3 out of 4 features must be present:

  • Opsoclonus
  • Ataxia and/or myoclonus
  • Behavioural changes or sleep disturbances
  • Neuroblastoma

Spinal tap:

  • Antibodies (oligoclonal bands) in CSF

Lymphocyte flow cytometry:

  • ↑ CD20+ B-cells in CSF

Imaging tests: CT/MRI/PET-CT

  • Location of tumour

Differential diagnosis:

  • Acute cerebellar ataxia of childhood

Management

Immunosuppressive therapy +  treatment of tumour (if present)

Immunosuppressive therapy:

  • Corticosteroids
  • Adrenocorticotropic hormone
  • Intravenous immunoglobulins (IV-Ig)
  • Cyclophosphamide
  • Rituximab
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An algorithm for the evaluation and management of opsoclonus myoclonus ataxia syndrome | Huddar A, Bindu PS, Nagappa M, Bharath RD, Sinha S, Mathuranath PS, Taly AB. Pediatric opsoclonus-myoclonus-ataxia syndrome: Experience from a tertiary care university hospital. Neurol India 2018;66:1332-7

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