Rituxan has been reported to alleviate the myoclonus opsoclonus syndrome in case reports and series. Presumably there is an immunologic mechanism underlying this observation. Approximately 50 % of patients with OMS have an associated neuroblastoma or associated infections have also been reported. There is no specific diagnostic biomarker for OMS. Other treatments include as ACTH, corticosteroids, cyclophosphamide and/or intravenous immunoglobulin, develop long-term neurological morbidity. Gordon in a 2011 review concldued that future collaborative studies are needed to determine if early, aggressive therapy will improve the typically poor long-term neurological outcome.
Pranzatelli et al (2010) reported the findings of 12 immunotherapy-naïve children with opsoclonus-myoclonus syndrome (OMS) and cerebrospinal fluid (CSF) B cell expansion who received rituximab, adrenocorticotropic hormone (ACTH), and Iintravenous immunoglobulin. Motor severity lessened 73 % by 6 months and 81 % at 1 year (p < 0.0001). Opsoclonus and action myoclonus disappeared rapidly, whereas gait ataxia and some other motor components improved more slowly. Dosage of ACTH was tapered by 87 %. Reduction in total CSF B cells was profound at 6 months (-93 %). By study end, peripheral B cells returned to 53 % of baseline and serum IgM levels to 63 %. Overall clinical response trailed peripheral B cell and IgM depletion, but improvement continued after their levels recovered. All but 1 non-ambulatory subject became ambulatory without additional chemotherapy; 2 relapsed and remitted; 4 had rituximab-related or possibly related adverse events; and 2 had low-titer human anti-chimeric antibody. The authors concluded that combination of rituximab with conventional agents as initial therapy was effective and safe. They stated that a controlled trial with long-term safety monitoring is indicated.
The proposed treatment is in clinical trials, for example, Use of Rituximab in Opsoclonus-Myoclonus in Children With Neuroblastoma, NCT00202930.
J. K. Sahu et al, The opsoclonus–myoclonus syndrome, Pract Neurol 2011;11:160-166
Gorman MP. Update on diagnosis, treatment, and prognosis in opsoclonus-myoclonus-ataxia syndrome. Curr Opin Pediatr. 2010;22(6):745-750.
Pranzatelli MR, Tate ED, Swan JA, et al. B cell depletion therapy for new-onset opsoclonus-myoclonus. Mov Disord. 2010;25(2):238-242.
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