New technologies for the assessment of neuropathies

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Hereditary neuropathies may be misdiagnosed with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). A correct diagnosis is crucial for avoiding unnecessary therapies and access genetic counseling. We report on nine patients (seven men, mean age 49.2 ± 16.1) diagnosed with and treated as CIDP, in whom mutations or variants of unknown significance (VUS) in genes associated with hereditary neuropathies were reported. All underwent neurological and neurophysiological examination, eight also cerebrospinal fluid (CSF) analysis. In 4/9, nerve ultrasound and/or MR‐neurography were performed. All the patients complained of progressive upper or lower limbs sensory‐motor symptoms, with heterogeneous disease duration (1‐34 years, mean 8.6 ± 10.8). Neurophysiology showed demyelinating signs in seven patients, mixed findings with predominant axonal damage in two patients. Neuroimaging disclosed diffuse abnormalities at proximal and distal segments. Molecular screening showed PMP22 duplication in two patients, mutations in the MPZ, EGR2, and GJB1 genes were reported in each of the remaining patients. The two patients with mixed neurophysiological findings had p.Val30Met mutation in the transthyretin gene. Two patients had VUS in the MARS and HSPB1 genes. Four patients had partial response to immunomodulant therapies, and CSF and neurophysiological features suggesting an inflammatory condition concomitant with the hereditary neuropathy. Hereditary neuropathy may be misdiagnosed with CIDP. The most common pitfalls are CSF (high protein levels and oligoclonal bands), incorrect interpretation of neurophysiology, and transient benefit from therapies. Neuroimaging may be helpful in cases with atypical presentations or when severe axonal damage complicate the neurophysiological interpretation.

Section: Discussionmentioning

confidence: 99%

“…Transient or lack of benefit from immunomodulatory therapies should lead to consider a hereditary neuropathy. Neuroimaging may be helpful in the diagnostic workup …”

Section: Discussionmentioning

confidence: 99%

Sporadic hereditary neuropathies misdiagnosed as chronic inflammatory demyelinating polyradiculoneuropathy: Pitfalls and red flags

Campagnolo

Taioli

Cacciavillani³

et al. 2020

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“…Recently, the availability of Magnetic resonance neurography (multiplanar T2‐based sequences with fat suppression) has allowed a better evaluation of specific nerve morphological features (such as caliber, internal fascicular pattern and the amount of perineurial‐endoneurial fluid), thus implementing the conventional MRI where injured plexus showed hypertense and enhanced signal. Additional radiological hints of post‐radiation plexopathy may be found in the surrounding tissues . The implementation of magnetic resonance neurography with diffusion‐weighted sequences appears promising in the investigation of cancer patient .…”

Section: Plexopathiesmentioning

confidence: 99%

Peripheral nervous system involvement in lymphomas

Briani

Visentin

Campagnolo

et al. 2019

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The peripheral nervous system may be involved at any stage in the course of lymphoproliferative diseases. The different underlying mechanisms include neurotoxicity secondary to chemotherapy, direct nerve infiltration (neurolymphomatosis), infections, immune‐mediated, paraneoplastic or metabolic processes and nutritional deficiencies. Accordingly, the clinical features are heterogeneous and depend on the localization of the damage (ganglia, roots, plexi, and peripheral nerves) and on the involved structures (myelin, axon, and cell body). Some clinical findings, such a focal or diffuse involvement, symmetric or asymmetric pattern, presence of pain may point to the correct diagnosis. Besides a thorough medical history and neurological examination, neurophysiological studies, cerebrospinal fluid analysis, nerve biopsy (in selected patients with suspected lymphomatous infiltration) and neuroimaging techniques (magnetic resonance neurography and nerve ultrasound) may be crucial for a proper diagnostic workup.

“…In the past years, new technologies for the assessment of peripheral neuropathies, including SFN, have become available . A number of diagnostic tools are available for the detection of SFN (Table ).…”

Section: Epidemiologymentioning

confidence: 99%

Small‐fiber neuropathy: Expanding the clinical pain universe

Sopacua

Hoeijmakers

Merkies

et al. 2019

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Small‐fiber neuropathy (SFN) is a disorder of thinly myelinated Aδ and unmyelinated C fibers. SFN is clinically dominated by neuropathic pain and autonomic complaints, leading to a significant reduction in quality of life. According to international criteria, the diagnosis is established by the assessment of intraepidermal nerve fiber density and/or quantitative sensory testing. SFN is mainly associated with autoimmune diseases, sodium channel gene variants, diabetes mellitus, and vitamin B12 deficiencies, although in more than one half of patients no etiology can be identified. Recently, gain‐of‐function variants in the genes encoding for the Nav1.7, Nav1.8 and Nav1.9 sodium channel subunits have been discovered in SFN patients, enlarging the spectrum of underlying conditions. Sodium channel gene variants associated with SFN can lead to a diversity of phenotypes, including different pain distributions and presence or absence of autonomic symptoms. This suggests that SFN is part of a clinical continuum. New assessments might contribute to a better understanding of the cellular and molecular substrates of SFN and might provide improved diagnostic methods and trial designs in the future. Identification of the underlying mechanisms may inform the development of drugs that more effectively address neuropathic pain and autonomic symptoms of SFN.