{'fraction_non_alphanumeric': 0.02092511013215859, 'fraction_numerical': 0.003854625550660793, 'mean_word_length': 5.617486338797814, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Factors influencing cognitive outcome in opsoclonus–myoclonus syndrome

Opsoclonus–myoclonus syndrome (OMS) presents as an acute or subacute encephalopathy, manifested by the presence of ataxia, irritability, myoclonus, and opsoclonus (rapid, involuntary eye movements). Inadequate therapy and lack of remission leads to chronic motor deficits and significant cognitive and behavioural sequelae. Sheridan et al.’s retrospective study reports reduced IQ overall in survivors of childhood OMS, with 22% identified with intellectual disability and another 24% having milder learning difficulties. The presence of intellectual and behavioural dysfunction is congruent with previous studies. OMS duration at time of neuropsychology testing is noted to be between 4 and 239 months, it is unclear if this means how long the patients have been symptomatic for or if this is the follow-up since symptom onset no matter if they are in remission or not. Remission was achieved in only 60% of patients who were eligible for neuropsychology evaluation in this cohort. Ongoing OMS symptoms suggests active encephalopathy in 40%, likely contributing to the reduced full-scale IQ scores, confirming the disabling nature of this chronic disease in the absence of remission. Twenty-six (32%) of the cohort did not have a neuropsychology evaluation. This was due to normal cognition in only four patients, suggesting that the proportion of patients in the study with intellectual disability is likely underestimated. Sheridan et al.’s study provides important insight into the factors significantly influencing the cognitive outcome of patients with OMS. This retrospective study does not identify an association between intensity of therapy, severity of disease at onset, or duration of disease before initiation of therapy; factors considered of potential importance. However, there is a noted important association with persistent symptoms, lack of remission at last follow-up, as well as increased relapses with an inferior long-term cognitive outcome. OMS is a neuroinflammatory disorder with associated elevated oligoclonal bands and cerebrospinal fluid B-cell expansion, or abnormality of Tcells in the minority of patients. There is mounting evidence that inducing a long-lasting clinical remission and reducing relapses is imperative to optimize long-term motor and cognitive function. In the era of established evidence in neuroimmunological disorders, early effective therapy and prevention of relapse is required to optimize outcome. Likewise, it is intuitive that early diagnosis, inducing clinical remission of OMS, and preventing relapse is of paramount importance to minimize long-term sequelae in OMS. Multiple studies recommend multimodality therapy at diagnosis including steroids, intravenous immunoglobulin or plasma exchange, and rituximab or cyclophosphamide. The issue of duration of immunomodulatory therapy or a maintenance phase of immunomodulation until the burn-out of the autoimmune disorder is not well elucidated but is a logical approach. During the course of the illness, prompt therapy of relapse is essential for a positive long-term outcome. Evaluating objective inflammatory markers can assist in management decisions in conjunction with the clinical course. Ongoing inflammation during clinical remission would be an indication to continue immunomodulatory therapy and provides insight into the best agent to use. Future international clinical trials need to address intensity and duration of therapy, biomarkers of active disease, and neurocognitive and behavioural outcomes for this rare disorder in childhood.