Long-term IVIg therapy effective in MMNCB

Authors of a study published in Neurology report that intravenous immunoglobulin (IVIg) therapy is an effective long-term therapy for multifocal motor neuropathy with conduction blocks (MMNCB).Dr Vucic and colleagues assessed the effect of IVIg therapy in 10 patients with MMNCB over an average of 7.25 years. They found "significant and sustained improvements in muscle strength and functional disability while on IVIg therapy" and a "significant improvement in CB [conduction blocks], decrease in AD [axonal degeneration], and evidence of reinnervation by the end of the follow-up period."Although IVIg therapy led to sustained improvements, all but one patient remained dependant on therapy. However, secondary IVIg resistance or increased IVIg requirements were not observed.The authors note that several previous open and placebo-controlled studies have established the short-term efficacy of IVIg. However, only a few studies have addressed long-term efficacy of IVIg in MMNCB. They describe the results from a study by the Utrecht group, which evaluated long-term clinical and neurophysiologic outcomes: "Although significant clinical improvement was documented, they found an overall increase in the number of CBs and degree of AD during the course of their study." The authors argue that the differences in long-term efficacy results in their study compared to the Utrecht study may have been due to the different IVIg dosing regimens. Dr Vucic and colleagues used larger mean IVIg maintenance doses than the Utrecht group (1.63g/kg for four weeks vs 0.54g/kg for four weeks). They say that the dose must be tailored to each patient, according to the clinical efficacy of IVIg - measured by the muscle strength testing.The authors add, "Our data suggest that the sustained clinical improvement is the result of significant resolution of CB, decrease in the degree of ongoing AD, and the development of reinnervation. Based on a comparison with studies by the Utrecht group, these effects appear to depend on the mean IVIg maintenance dose."Reference...