Novel manifestations of anti-myelin–associated glycoprotein (MAG) antibodies neuropathy

Abstract

INTRODUCTION: Anti-myelin–associated glycoprotein (anti-MAG) antibodies–associated peripheral neuropathy (anti-MAG neuropathy) is detected in approximately 50% of patients presenting with demyelinating neuropathy and immunoglobulin (Ig) M monoclonal gammopathy. The typical presentation of anti-MAG neuropathy is that of distal, predominantly sensory large-fibre ataxic neuropathy progressive over years or decades. The rate of progression is variable. METHODS: We retrospectively studied clinical features of Chinese anti-MAG neuropathy patients diagnosed and cared for in Queen Mary Hospital (QMH) for the past 10 years’ (January 2005 to December 2014) duration. RESULTS: During the study period, there were 18 patients with idiopathic chronic inflammatory demyelinating polyneuropathy (iCIDP)—six CIDP associated with monoclonal gammopathy of uncertain significance (MGUS), two POEMS (polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy, and skin changes), two anti-MAG neuropathy, and one CIDP associated with myeloma, diagnosed and cared for in QMH. The clinical and electrophysiological features of the iCIDP, CIDP with MGUS, POEMS, and CIDP with myeloma were similar to that of reported series. The two patients with anti-MAG neuropathy had novel neurological presentations. One presented with acute rapidly progressive demyelinating polyneuropathies fulfilling diagnostic criteria of Guillain-Barre syndrome (GBS) that did not respond to intravenous Ig and progressed to severe generalized weakness with respiratory involvement with marked secondary axonal degeneration on nerve conduction study (NCS). The patient gradually recovered with prolonged therapy with azathioprine and steroid. The other patient presented with diplopia due to bilateral abducens and right facial nerve palsy with NCS confirmed demyelinating neuropathy associated with hyperviscosity from IgM monoclonal gammopathy. He completely recovered following therapy with fludarabine, dexamethasone, and mycophenolate mofetil. CONCLUSION: Anti-MAG neuropathy in Hong Kong Chinese patients may present as GBS or multiple cranial neuropathies with good response to immunosuppressant therapies.