The diagnostic evaluation of a peripheral neuropathy includes testing for the presence of monoclonal gammopathy, which can be found in about 10% of patients with peripheral neuropathy. Our role, as physicians, is to determine whether the neuropathy is directly related to the gammopathy or whether the co-occurrence of these two disorders is purely coincidental. The evaluating physician needs to be familiar with the different types of neuropathies associated with monoclonal gammopathies, their clinical and electrodiagnostic characteristics, and their appropriate diagnostic evaluation and management. Testing for monoclonal protein disorders includes serum protein electrophoresis (SPEP) and immunofixation of blood, and in some cases of urine, as well as measurement of free light chains and quantitative immunoglobulins. Specific antibody testing is directed by paraprotein type and neuropathy phenotype. Patients with abnormal free light chains in association with sensory and autonomic neuropathy should be evaluated for AL amyloidosis. When a lambda monoclonal protein is identified together with a clinical phenotype of chronic inflammatory demyelinating neuropathy (CIDP), a diagnosis of polyneuropathy, organomegaly, endocrinopathy, monoclonal plasma cell disorder, skin changes (POEMS) syndrome should be considered. Patients with IgM paraprotein associated neuropathy should be assessed for distal acquired demyelinating sensorimotor (DADS) neuropathy, with or without anti myelin associated glycoprotein (MAG) antibody or CANOMAD syndrome. In many cases, a monoclonal gammopathy of uncertain significance (MGUS) is incidental and unrelated to the neuropathy. Collaboration with oncology is critical in evaluating patients with monoclonal proteins to assess for underlying plasma cell neoplasms or B cell lymphomas.

To investigate the ocular manifestations in 91 Waldenström's macroglobulinemia (WM) patients. Retrospective, cross-sectional, observational analysis. Ocular impairments, detected in 19 patients, included flame-shaped hemorrhages, venous sausaging, papilledema, macular detachments, or central retinal vein occlusion in 16 patients; paraproteinemic keratopathy in 2; and a CANOMAD syndrome in 1. Best-corrected visual acuity was ≥0.5 logMAR units in 11 of 38 eyes. Intraocular pressure was increased in seven eyes. Genetic analysis in seven patients showed a mutation in the MYD88 gene in six patients and a nonsense mutation in the CXCR4 gene in five patients. Plasmapheresis followed by chemotherapy with or without the addition of rituximab resulted in improvement or normalization of the ophthalmological findings in 15 patients. The ocular manifestations of WM are protean and potentially sight threatening. Recent advances in genomic profiling and chemotherapy have remarkably improved the hematological and ophthalmological outcomes of these patients.

To report our experience with a group of patients referred for refractory CIDP who fulfilled "definite" electrodiagnostic EFNS criteria for CIDP but were found to have an alternate diagnosis. Patients who were seen between 2017 and 2019 for refractory CIDP that fulfilled "definite" electrodiagnostic ENFS criteria for CIDP, but had an alternate diagnosis, were included. Patients who correctly had CIDP, anti MAG neuropathy, or MMN with conduction block, were excluded from the study. Demographics, clinical and electrophysiological characteristics, pertinent workup, final alternate diagnoses, and outcomes were collected. Seven patients were included: POEMS (n = 5), CANOMAD (n = 1), and neurolymphomatosis (n = 1). Most patients reported neuropathic pain and leg swelling (n = 6) or significant weight loss (n = 4). All patients had a monoclonal protein, and most patients who were tested had an elevated VEGF and CSF cyto-albuminologic dissociation. Electrophysiology showed pronounced intermediate more than distal demyelination, and axonal loss in the lower extremities. Response to steroids or IVIG varied, but some patients did respond to these treatments, especially early in the disease. Pain, systemic symptoms, suggestive electrophysiological findings, and/or a serum monoclonal protein should raise suspicion for CIDP mimics. Initial response to steroids or IVIG, over reliance on CSF, and electrophysiology findings can all be misleading.

Monoclonal gammopathy is encountered quite frequently in the general population. This type of hematologic abnormality may be mild, referred to as monoclonal gammopathy of undetermined significance or related to different types of hematologic malignancies. The association of a peripheral neuropathy with monoclonal gammopathy is also fairly common, and hemopathy may be discovered in an investigation of peripheral neuropathy. In such a situation, it is essential to determine the exact nature of the hematologic process in order not to miss a malignant disease and thus initiate the appropriate treatment (in conjunction with hematologists and oncologists). In this respect, nerve biopsy (discussed on a case-by-case basis) is of great value in the management of such patients. We therefore propose to present the objectives and main interests of nerve biopsy in this situation.

Our objective was to evaluate whether IV immunoglobulin (IVIg) increases the risk of thromboembolic events in neurology outpatients with inflammatory neuropathies, as there is conflicting evidence supporting this hypothesis, mainly from non-neurologic cohorts. We investigated this question over 30 months in our cohort of patients with inflammatory neuropathies receiving regular IVIg and found a greater incidence of arterial and venous thromboembolic events than population-based rates determined by hospital admissions data. Vascular risk factors were more common in the event group but there were no IVIg administration factors that contributed to the risk. This study suggests that IVIg may have a small but contributory role in determining thromboembolic risk in the inflammatory neuropathy cohort and more evidence is required before it is clear whether the current primary prevention guidelines are appropriate in this group of patients.