Neuropathy associated with immunoglobulin M monoclonal gammopathy: A combined sonographic and nerve conduction study

Abstract

Introduction We assessed the specific sonographic pattern of structural nerve abnormalities in immunoglobulin M (IgM) neuropathy and disease controls. Methods We enrolled 106 incident patients—32 patients with IgM neuropathy, 42 treatment‐naive patients with chronic inflammatory demyelinating polyneuropathy, and 32 patients with axonal neuropathies. All patients underwent standardized ancillary testing in addition to standardized sonography of the brachial plexus and the large arm and leg nerves bilaterally. Results We found widespread nerve enlargement in IgM neuropathy and chronic inflammatory demyelinating polyneuropathy (CIDP), with specific enlargement of brachial plexus and proximal segments of median nerve but not in axonal disease controls (P < .001). Sonographic nerve hypertrophy in IgM neuropathy was not associated with nerve conduction, clinical, or laboratory characteristics. Discussion Immunoglobulin M neuropathy is characterized by widespread nerve enlargement indistinguishable from CIDP. Our data provide evidence to confirm that the disease process is not confined to the more distal parts of nerves in either classical demyelinating or axonal variants of neuropathy with associated IgM.

Nerve Hypertrophy and Altered Diffusion in Anti-Myelin-Associated Glycoprotein Neuropathy Detected by Brachial Plexus Magnetic Resonance Neurography

“…DTI, diffusion tensor imaging; CSA, cross-sectional area; FA, fractional anisotropy; MD, mean diffusivity; RD, radial diffusivity; AD, axial diffusivity. 100 DOI: 10.1159/000519128 ment, including the brachial plexus and nerve root [18,19]. Goedee et al [18] showed sonographic enlargement of the brachial plexus in 26 of 32 patients with IgM neuropathy (including 21 patients with anti-MAG neuropathy).…”

“…In an autopsy study, it has been shown that IgM deposition occurs in both distal and proximal nerves [2]. Furthermore, sonographic studies have shown widespread nerve enlargement, including the brachial plexus and nerve root [18, 19]. Goedee et al [18] showed sonographic enlargement of the brachial plexus in 26 of 32 patients with IgM neuropathy (including 21 patients with anti-MAG neuropathy).…”

“…Furthermore, sonographic studies have shown widespread nerve enlargement, including the brachial plexus and nerve root [18, 19]. Goedee et al [18] showed sonographic enlargement of the brachial plexus in 26 of 32 patients with IgM neuropathy (including 21 patients with anti-MAG neuropathy). Another sonographic study has shown that the CSA of the nerve roots tended to be larger in patients with anti-MAG neuropathy than that in the control group [19].…”

Review Article “Spotlight on Ultrasonography in the Diagnosis of Peripheral Nerve Disease: The Evidence to Date”

“…Anti-MAG is an immune mediated demyelinating neuropathy with distally predominant symmetrical sensorimotor impairment and prolonged distal motor latencies on EDX. Despite this the ultrasound abnormalities tend to be proximal 144 and there are no reports of distal nerve enlargement. Segmental nerve enlargement has been described in cervical nerve roots, brachial plexus, and proximal nerve segments 145 with considerable inter-nerve variability.…”

Current and future applications of ultrasound imaging in peripheral nerve disorders

“…In axonal neuropathy associated with monoclonal gammopathy of uncertain significance and multiple myeloma typically no nerve enlargement is found[ 255 , 256 ]. However, in two cases where nerve enlargement was identified in this axonal cohort, management was altered to include immunotherapy with a beneficial outcome[ 255 ], suggesting that nerve enlargement may also facilitate therapeutic decision making in these paraproteinaemic axonal neuropathies.…”