High-Resolution Nerve Ultrasound Abnormalities in POEMS Syndrome-A Comparative Study.

BACKGROUND: High-resolution nerve ultrasound (HRUS) has been proven to be a valuable tool in the diagnosis of immune-mediated neuropathies, such as chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). POEMS syndrome (polyneuropathy, organomegaly, endocrinopathy, M-protein, skin changes) is an important differential diagnosis of CIDP. Until now, there have been no studies that could identify specific HRUS abnormalities in POEMS syndrome patients. Thus, the aim of this study was to assess possible changes and compare findings with CIDP patients. METHODS: We retrospectively analyzed HRUS findings in three POEMS syndrome and ten CIDP patients by evaluating cross-sectional nerve area (CSA), echogenicity and additionally calculating ultrasound pattern scores (UPSA, UPSB, UPSC and UPSS) and homogeneity scores (HS). RESULTS: CIDP patients showed greater CSA enlargement and higher UPSS (median 14 vs. 11), UPSA (median 11.5 vs. 8) and HS (median 5 vs. 3) compared with POEMS syndrome patients. However, every POEMS syndrome patient illustrated enlarged nerves exceeding reference values, which were not restricted to entrapment sites. In CIDP and POEMS syndrome, heterogeneous enlargement patterns could be identified, such as inhomogeneous, homogeneous and regional nerve enlargement. HRUS in CIDP patients visualized both increased and decreased echointensity, while POEMS syndrome patients pictured hypoechoic nerves with hyperechoic intraneural connective tissue. Discussion: This is the first study to demonstrate HRUS abnormalities in POEMS syndrome outside of common entrapment sites. Although nerve enlargement was more prominent in CIDP, POEMS syndrome patients revealed distinct echogenicity patterns, which might aid in its differentiation from CIDP. Future studies should consider HRUS and its possible role in determining diagnosis, prognosis and treatment response in POEMS syndrome.

Nerve Ultrasound as Helpful Tool in Polyneuropathies.

BACKGROUND: Polyneuropathies (PNP) are a broad field of diseases affecting millions of people. While the symptoms presented are mostly similar, underlying causes are abundant. Thus, early identification of treatable causes is often difficult. Besides clinical data and basic laboratory findings, nerve conduction studies are crucial for etiological classification, yet limited. Besides Magnetic Resonance Imaging (MRI), high-resolution nerve ultrasound (HRUS) has become a noninvasive, fast, economic and available tool to help distinguish different types of nerve alterations in neuropathies. METHODS: We aim to describe typical ultrasound findings in PNP and patterns of morphological changes in hereditary, immune-mediated, diabetic, metabolic and neurodegenerative PNP. Literature research was performed in PubMed using the terms 'nerve ultrasound', neuromuscular ultrasound, high-resolution nerve ultrasound, peripheral nerves, nerve enlargement, demyelinating, hereditary, polyneuropathies, hypertrophy'. RESULTS: Plenty of studies over the past 20 years investigated the value of nerve ultrasound in different neuropathies. Next to nerve enlargement, patterns of nerve enlargement, echointensity, vascularization and elastography have been evaluated for diagnostic terms. Furthermore, different scores have been developed to distinguish different etiologies of PNP. CONCLUSIONS: Where morphological alterations of the nerves reflect underlying pathologies, early nerve ultrasound might enable a timely start of available treatment and also facilitate follow up of therapy success.

Tetraparesis and sensorimotor axonal polyneuropathy due to co-occurrence of Pompe disease and hereditary ATTR amyloidosis.

INTRODUCTION/AIMS: Hereditary transthyretin amyloidosis with polyneuropathy (hATTRPN) is an autosomal dominant multi-organ disorder manifesting in the third to fifth decade with the key clinical features of distal and painful sensory loss of the lower limbs and autonomic dysregulation. Motor neuropathy and cardiomyopathy evolve in the course of the disease. Pompe disease is an autosomal recessive disease leading to decreased levels of lysosomal enzyme acid α-glucosidase and proximal muscle weakness. We report the clinical features and diagnostic workup in the rare case of a patient with ATTR amyloidosis and late-onset Pompe disease, both genetically confirmed. METHODS: We performed a detailed clinical assessment, exome sequencing, and biochemical measurements. RESULTS: The patient presented with a distal, painful hypaesthesia of both legs, a cardiomyopathy, and a muscle weakness in the form of a girdle-type pattern of the arms and legs at the beginning and a spreading to distal muscle groups in the course of disease. DISCUSSION: This study highlights the importance of searching for co-occurrence of rare monogenetic neuromuscular diseases, especially in cases in which all clinical features can be readily explained by a single gene defect.

Peripheral Nerve Imaging Aids in the Diagnosis of Immune-Mediated Neuropathies-A Case Series.

BACKGROUND: Diagnosis of immune-mediated neuropathies and their differentiation from amyotrophic lateral sclerosis (ALS) can be challenging, especially at early disease stages. Accurate diagnosis is, however, important due to the different prognosis and available treatment options. We present one patient with a left-sided dorsal flexor paresis and initial suspicion of ALS and another with multifocal sensory deficits. In both, peripheral nerve imaging was the key for diagnosis. METHODS: We performed high-resolution nerve ultrasound (HRUS) and 7T or 3T magnetic resonance neurography (MRN). RESULTS: In both patients, HRUS revealed mild to severe, segmental or inhomogeneous, nerve enlargement at multiple sites, as well as an area increase of isolated fascicles. MRN depicted T2 hyperintense nerves with additional contrast-enhancement. DISCUSSION: Peripheral nerve imaging was compatible with the respective diagnosis of an immune-mediated neuropathy, i.e., multifocal motor neuropathy (MMN) in patient 1 and multifocal acquired demyelinating sensory and motor neuropathy (MADSAM) in patient 2. Peripheral nerve imaging, especially HRUS, should play an important role in the diagnostic work-up for immune-mediated neuropathies and their differentiation from ALS.

Normative Observational Nerve Ultrasound Values in School-Age Children and Adolescents and Their Application to Hereditary Neuropathies.

Backgrounds: We have aimed to establish nerve ultrasound reference data in 8 to 17-year-old children and adolescents and to compare those data to younger children, adults, and age-matched children with polyneuropathies. Methods: High-resolution ultrasounds of the nerves were performed in 117 healthy children and adolescents at 20 predefined landmarks in the neck and the extremities of both sides. Mean values, side-to-side differences and intraneural ratios, as well as upper limits have been calculated. In a second step, a comparison between 25 children and adolescents of the same age range with proven hereditary and acquired neuropathies and lysosomal storage diseases has been carried out. Results: Nerve growth correlates significantly with age and reaches adult values at the age of around 15 years. The influence of body mass index and gender is negligible at most segments. By the use of age-specific upper limits, nerve enlargement could be seen in distinct types of neuropathies, particularly in demyelinating hereditary and inflammatory types, which is comparable to findings in adults, but also in rare lysosomal storage diseases. Conclusion: Nerve size correlates with age during childhood and reaches a climax in younger adults. Age-matched reference data are inevitable to differ between hypertrophic and non-hypertrophic nerve damage, e.g., in neuropathies.

Different Effects of α-Synuclein Mutants on Lipid Binding and Aggregation Detected by Single Molecule Fluorescence Spectroscopy and ThT Fluorescence-Based Measurements.

Six α-synuclein (aSyn) point mutations are currently known to be associated with familial parkinsonism: A30P, E46K, H50Q, G51D, A53E, and A53T. We performed a comprehensive in vitro analysis to study the impact of all aSyn mutations on lipid binding and aggregation behavior. Markedly reduced lipid binding of A30P, moderately attenuated binding of G51D, and only very slightly reduced binding for the other mutants were observed. A30P was particularly prone to form metal ion induced oligomers, whereas A53T exhibited only weak tendencies to form oligomers. In turn, fibril formation occurred rapidly in H50Q, G51D, and A53T, but only slowly in A30P, suggesting mutants prone to form oligomers tend to form fibrils to a lesser extent. This was supported by the observation that fibril formation of wild type aSyn, A30P, and A53T was impaired in the presence of ferric iron. Additionally, we found the aggregation kinetics of mixtures of A30P or A53T and wt aSyn to be determined by the faster aggregating aSyn variant. Our results implicate differential mechanisms playing a role in aSyn pathology on the molecular level. This might contribute to a better understanding of Parkinson's disease pathogenesis and provide potential links to develop prevention strategies and disease-modifying therapy.