===== Western vs optic-spinal MS -Two diseases, one treatment?- 西洋型MS vs OSMS −二つの病型に同一の治療?− Brian Wenshenker (Mayo Clinic)
(前略) In the study by Saida et al., 21% of enrolled patients had the optic-spinal form of MS. Patients with western MS and optic-spinal MS were not separately randomized nor was the study powered to assess the efficacy of treatment in this subgroup. Given the differences between these two subgroups, it was quite reasonable to stratify the analysis of efficacy to evaluate for potential differences. However, there were important limitations of such stratification, even beyond the limited statistical power. The MRI data that are so helpful in assessing efficacy of treatment in MS would not apply to optic-spinal MS as the MRI of the brain is and usually remains normal. The study results suggest a nonsignificant trend to reduction of relapse frequency, but no effect on proportion relapse free, a measure consistently positively impacted in other relapsing remitting MS trials. The discrepancy could be due to inadequate power, and the trend regarding the attack frequency outcome may mean that interferon beta is effective in optic-spinal MS. However, neurologists who care for patients with optic-spinal MS/NMO should be reluctant to accept these results as definitive proof of efficacy in this subgroup.
Given the differences between NMO/optic-spinal MS and western MS clinically and pathologically, future clinical trials should endeavor to distinguish patients with these conditions. Japanese clinicians have traditionally been better able to recognize this condition, as they have not required bilateral optic neuritis and nearly simultaneous optic neuritis and myelitis. Because of the traditional adherence to these criteria, many patients with NMO in North America may be misdiagnosed as having MS. Randomized controlled studies in this subgroup, whose sufferers often experience very aggressive disease, are needed. New, liberalized, but evidence-based diagnostic criteria9 and new serologic tests7 will help distinguish these cases from those with prototypic western MS and will facilitate clinical trials for this disorder.
However, neurologists who care for patients with optic-spinal MS/NMO should be reluctant to accept these results as definitive proof of efficacy in this subgroup.