Ultra-high dose of intravenous immunoglobulin restores strength and motor function in a patient with refractory multifocal motor neuropathy

Multifocal motor neuropathy (MMN) is a chronic progressive immune-mediated neuropathy, predominantly involving upper limbs asymmetrically with electrophysiologic evidence of motor conduction block. The treatment of choice is immunoglobulin (Ig). Nevertheless, some patients may become resistant to treatment. We describe a patient with history of MMN who became resistant to gammaglobulin treatment but markedly improved using ultra-high doses of intravenous immunoglobulin.

A 36-year-old woman with diagnosis of MMN. After 5 years of clinical stability under subcutaneous Ig (2g/kg/month) the patient developed bilateral weakness involving both hands. Treatment was switched to intravenous Ig 2g/kg/month, nevertheless, she progressed and became totally dependent for activities of daily living. We started ultra-high dose intravenous immunoglobulin 5 g/kg/month, with good response. She became independent for activities of daily living and returned to work. The only treatment related adverse event was headache during infusion.

Ultra-high dose intravenous Ig seems to be a useful therapy in aggressive MMN with severe disability despite conventional treatment. A low cardiovascular risk score (QRISK2 less than 10%) and a daily intravenous Ig lower than 35 g reduce the risk of severe complications related to intravenous Ig.