Chronic motor neuropathies: response to interferon-beta 1a after failure of conventional therapies

Objectives-The effect of interferon-pla (LNF-beta 1a; Rebif(R)) was studied in patients with chronic motor neuropathies not improving after convention al treatments such as immunoglobulins, steroids, cyclophosphamide or plasma exchange. Methods-A prospective open study was performed with a duration of 6-12 mont hs. Three patients with a multifocal motor neuropathy and one patient with a pure motor form of chronic inflammatory demyelinating polyneuropathy were enrolled. Three patients had anti-GM1 antibodies. Treatment consisted of s ubcutaneous injections of IBF-beta 1a (6 MIU), three times a week. Primary outcome was assessed at the level of disability using the nine hole peg tes t, the 10 metres walking test, and the modified Rankin scale. Secondary out come was measured at the impairment level using a slightly modified MRC sum score. Results-All patients showed a significant improvement on the modified MRC s umscore. The time required to walk 10 metres and to fulfil the nine hole pe g test was also significantly reduced in the first 3 months in most patient s. However, the translation of these results to functional improvement on t he modified Rankin was only seen in two patients. There were no severe adve rse events. Motor conduction blocks were partially restored in one patient on Anti-GM1 antibody titres did not change. Conclusion-These findings indicate that severely affected patients with chr onic motor neuropathies not responding to conventional therapies may improv e when treated with INF-beta 1a. From this study it is suggested that INF-b eta 1a should be administered in patients with chronic motor neuropathies f or a period of up to 3 months before deciding to cease treatment. A control led trial is necessary to confirm these findings.