Dyck, P. James B.

ABSTRACTIntravenous immunoglobulin [IVIg], plasma exchange [PE], and corticosteroids are efficacious treatment in chronic inflammatory demyelinating polyneuropathy [CIDP]. IVIg is effective in multifocal motor neuropathy [MMN]. NIS, NIS‐weakness, sum scores of raw amplitudes of motor fiber (CMAPs) amplitudes, and Dyck/Rankin score provided reliable measures to detect and scale abnormality and reflect change; they are therefore ideal for office management of response‐based immunotherapy (R‐IRx) of CIDP. Using efficacious R‐IRx, a large early and late therapeutic response (≥ one‐fourth were in remission or had recovered) was demonstrated in CIDP. In MMN only an early improvement with late non‐significant worsening was observed. The difference in immunotherapy response supports a fundamental difference between CIDP (immune attack on Schwann cells and myelin) and MMN (attack on nodes of Ranvier and axons). Muscle Nerve 52: 488–497, 2015

ABSTRACTIntroductionNeurolymphomatosis (NL) is a rare disorder characterized by invasion of cranial or peripheral nerves, nerve roots, or plexi, usually by aggressive subtypes of non‐Hodgkin lymphoma (NHL). The most common clinical presentation is that of a painful polyneuropathy or polyradiculopathy, followed by cranial neuropathy and, less frequently, by painless polyneuropathy.MethodsClinical and pathologic findings are reported for 2 NL cases.ResultsThe following 2 patients with NL, with disparate clinical presentations, are presented: a patient with subacute onset, painful, multifocal, mixed axonal and demyelinating radiculoplexus neuropathy due to a large B‐cell NHL, who required 2 targeted fascicular nerve biopsies to demonstrate NL; and a patient with a slowly progressive, length‐dependent axonal polyneuropathy due to a low‐grade B‐cell lymphoproliferative disorder, as shown on a diagnostic sural nerve biopsy.ConclusionsThe cases described illustrate the wide clinical spectrum of NL. Muscle Nerve 52:449–454, 2015

ABSTRACTIntroduction: A 24‐year‐old man with primary hyperoxaluria type 1 (PH1) presented with a rapidly progressive axonal and demyelinating sensorimotor polyradiculoneuropathy shortly after the onset of end‐stage renal disease. His plasma oxalate level was markedly elevated at 107 µmol/L (normal <1.8 µmol/L). Methods: A sural nerve biopsy was performed. Teased fiber and paraffin and epoxy sections were done and morphometric procedures were performed on this sample and on an archived sample from a 22‐year‐old man as an age‐ and gender‐matched control. Embedded teased fiber electron microscopy was also performed. Results: The biopsy revealed secondary demyelination and axonal degeneration. Under polarized light, multiple bright hexagonal, rectangular, and starburst inclusions, typical of calcium oxalate monohydrate crystals, were seen. Conclusions: The proposed mechanisms of nerve damage include disruption of axonal transport due to crystal deposition, toxic effect of oxalate, or nerve ischemia related to vessel occlusion from oxalate crystal deposition. Muscle Nerve 51: 449–454, 2015

ABSTRACTIntroductionThe Cl. NPhys Trial 3 showed that attributes of nerve conduction (NC) were without significant intraobserver differences, although there were significant interobserver differences. Methods: Trial 4 tested whether use of written instructions and pretrial agreement on techniques and use of standard reference values, diagnostic percentile values, or broader categorization of abnormality could reduce significant interobserver disagreement and improve agreement among clinical neurophysiologists. Results: The Trial 4 modifications markedly decreased, but did not eliminate, significant interobserver differences of measured attributes of NC. Use of standard reference values and defined percentile values of abnormality decreased interobserver disagreement and improved agreement of judgment of abnormality among evaluators. Therefore, the same clinical neurophysiologist should perform repeat NCs of therapeutic trial patients. Conclusions: Differences in interobserver judgment of abnormality decrease with use of common standard reference values and a defined percentile level of abnormality, providing a rationale for their use in therapeutic trials and medical practice. Muscle Nerve 50: 900–908, 2014