Early Onset and Severe Clinical Course Associated with the m.5540G>A Mutation in MT-TW.

We report a patient harboring a de novo m.5540G>A mutation affecting the MT-TW gene coding for the mitochondrial tryptophan-transfer RNA. This patient presented with atonic-myoclonic epilepsy, bilateral sensorineural hearing loss, ataxia, motor regression, ptosis, and pigmentary retinopathy. Our proband had an earlier onset and more severe phenotype than the first reported patient harboring the same mutation. We discuss her clinical presentation and compare it with the only previously published case.

B cell depletion therapy for new-onset opsoclonus-myoclonus.

Twelve immunotherapy-naïve children with opsoclonus-myoclonus syndrome and CSF B cell expansion received rituximab, adrenocorticotropic hormone (ACTH), and IVIg. Motor severity lessened 73% by 6 mo and 81% at 1 yr (P < 0.0001). Opsoclonus and action myoclonus disappeared rapidly, whereas gait ataxia and some other motor components improved more slowly. ACTH dose was tapered by 87%. Reduction in total CSF B cells was profound at 6 mo (-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 one non-ambulatory subject became ambulatory without additional chemotherapy; two relapsed and remitted; four had rituximab-related or possibly related adverse events; and two had low-titer human anti-chimeric antibody. Combination of rituximab with conventional agents as initial therapy was effective and safe. A controlled trial with long-term safety monitoring is indicated.

Rituximab (anti-CD20) adjunctive therapy for opsoclonus-myoclonus syndrome.

PURPOSE: To determine if rituximab, an anti-CD20 monoclonal antibody, reduces cerebrospinal fluid (CSF) B-cell expansion in opsoclonus-myoclonus syndrome (OMS) and results in clinical improvement. METHODS: Sixteen children with OMS and increased % CD20 B-cells in CSF received 4 rituximab infusions (375 mg/m IV) as add-on therapy to corticotropin (ACTH), intravenous immunoglobulins, or both, and were reevaluated 6 months later. Outcome measures were clinical (motor function, behavior, sleep) and immunologic (CSF and blood immunophenotype and Ig levels). Controls were 16 age-matched and sex-matched children, who did not have OMS. RESULTS: After rituximab, 81% of OMS had a lower motor severity score, and 44% improved one severity category. Mean total score decreased by 44% (P = 0.0005). Rituximab reduced rage score, nighttime awakenings, and the number of children with opsoclonus, action myoclonus, drooling, gait ataxia, and rage. Despite a 51% reduction in ACTH dose, 9 of 11 children on ACTH did not relapse. The percentage of CSF CD19 (and CD20) B-cells was lowered in all children (undetectable in 6), with a 90% reduction in the group mean (P = 0.00003). CSF B-cells were no longer expanded compared with controls. In blood, CD19 B-cells decreased (-90%, P = 0.0003), as did the CSF:blood CD19 B-cell ratio (P = 0.00003). Serum IgM fell by 69% (below reference range), with no statistically significant change in IgG or IgA. CONCLUSIONS: Rituximab seems efficacious and safe as adjunctive therapy for OMS. Selective targeting of CSF B lymphocytes represents a novel and valuable paradigm shift in the therapy for centrally mediated paraneoplastic disorders.