The purpose of this study is to evaluate the efficacy and safety of HyQvia (Immunoglobulin 10% with recombinant hyaluronidase) with conventional subcutaneous immunoglobulin treatment in patients with Multifocal Motor Neuropathy (MMN).

Subcutaneous immunoglobulin (SCIG) therapy for MMN is equally efficacious to intravenous immunoglobulin (IGIV), may be self-induced and may induce fewer systemic adverse reactions. Limited SC infusion volumes and reduced bioavailability, however, necessitate multiple infusion sites, more frequent treatment, and dose adjustment to achieve pharmacokinetic equivalence. This is an issue in particular in MMN where relatively high and frequent doses are necessary to maintain long-term improvement of muscle strength. Recombinant human hyaluronidase (rHuPH20) increases subcutaneous tissue permeability and facilitates dispersion and absorption, enabling subcutaneous administration of higher (monthly) doses of Ig. If treatment with HyQvia is at least equally effective and safe as compared with conventional Ig treatment, HyQvia could become the preferred treatment option for patients with MMN as it may have attractive benefits for patients by its mode of administration.

Inclusion Criteria:

• Age at onset 18 - 65 years.
• The presence of asymmetrical limb weakness at onset or motor involvement having a motor nerve distribution in at least two peripheral nerve distributions, predominant upper limb involvement, disabling weakness MRC grade 4 or less in at least one muscle.
• Decreased or absent tendon reflexes in affected limbs.
• Electrophysiological evidence of one site with definite motor conduction block or one site with probable conduction block according to previously defined criteria.
• Response to SCIG according to criteria that were described in previous studies
• On SCIG maintenance treatment for more than 3 months preceding the study.
• Patients have given written informed consent, prior to the study, with the understanding that consent may be withdrawn at any time without prejudice.

Exclusion Criteria:

• Bulbar signs or symptoms.
• Upper motor neuron signs (spasticity, hyperreflexia, extensor plantar response).
• Sensory symptoms and signs with sensory deficits on examination (except for vibration sense) and abnormal results of sensory nerve conduction studies
• Other neuropathies (e.g. diabetic, lead, porphyric or vasculitic neuropathy, chronic inflammatory demyelinating polyneuropathy, Lyme neuroborreliosis, post radiation neuropathy, hereditary neuropathy with liability to pressure palsies, Charcot-Marie-Tooth neuropathies, meningeal carcinomatosis).
• Treatment with other immunosuppressive drugs (cyclophosphamide, azathioprine, cyclosporin) in the 6 months preceding the study.
• Female patient who is pregnant or breast-feeding or of childbearing potential.
• Confirmation that the patient is not pregnant will be established by a negative b-HCG test within a 7-day period before inclusion in the study. Lack of childbearing potential is met by a) being post-menopausal, b) being surgically sterile, c) practising contraception with an oral contraceptive, intra-uterine device, diaphragm or condom with spermicide or d) being sexually inactive.
• Age < 18 years