Amyloid Neuropathy: From Pathophysiology to Treatment in Light-Chain Amyloidosis and Hereditary Transthyretin Amyloidosis.

Amyloid neuropathy is caused by deposition of insoluble β-pleated amyloid sheets in the peripheral nervous system. It is most common in: (1) light-chain amyloidosis, a clonal non-proliferative plasma cell disorder in which fragments of immunoglobulin, light or heavy chain, deposit in tissues, and (2) hereditary transthyretin (ATTRv) amyloidosis, a disorder caused by autosomal dominant mutations in the TTR gene resulting in mutated protein that has a higher tendency to misfold. Amyloid fibrils deposit in the endoneurium of peripheral nerves, often extensive in the dorsal root ganglia and sympathetic ganglia, leading to atrophy of Schwann cells in proximity to amyloid fibrils and blood-nerve barrier disruption.

TS-HDS autoantibody: clinical characterization and utility from real-world tertiary care center experience.

Objectives: To evaluate clinical utility of trisulfated-heparin disaccharide (TS-HDS) IgM testing from real-world tertiary care center experience.

Methods: Medical records of patients with positive TS-HDS antibodies who were evaluated at Mayo Clinic from 2009 to 2022 were reviewed.

Results: Seventy-seven patients (50 females) had positive TS-HDS antibody.

Distal Tibial Mononeuropathy From Compression by the Posterior Tibial Artery: Clinical-Electrophysiological-Ultrasonographic Correlations.

The tibial nerve is bound tightly to the posterior tibial artery in the tarsal tunnel where expansion capacity is limited. Therefore, the nerve may be vulnerable to, and damaged by chronic pulsatile trauma from an atypically positioned overriding artery, labeled "punched-nerve syndrome". In this article, we present a 49-year-old woman who presented with two months of severe burning pain in the left medial ankle and sole of the foot without antecedent trauma.

Amyloid-like IgM deposition neuropathy with multiple mononeuropathies and generalized neuropathy.

Amyloid-like IgM deposition neuropathy is a distinct entity in the setting of IgM monoclonal gammopathy in which endoneurial perivascular entire IgM-particle accumulation leads to a painful sensory followed by motor peripheral neuropathy. We report a 77-year-old man presenting with progressive multiple mononeuropathies starting with painless right foot drop. Electrodiagnostic studies showed severe axonal sensory-motor neuropathy superimposed by multiple mononeuropathies.

GDP-Mannose Pyrophosphorylase B ()-Related Disorders.

GDP-mannose pyrophosphorylase B (GMPPB) is a cytoplasmic protein that catalyzes the formation of GDP-mannose. Impaired GMPPB function reduces the amount of GDP-mannose available for the O-mannosylation of α-dystroglycan (α-DG) and ultimately leads to disruptions of the link between α-DG and extracellular proteins, hence dystroglycanopathy. GMPPB-related disorders are inherited in an autosomal recessive manner and caused by mutations in either a homozygous or compound heterozygous state.

Symptomatic myopathies in sarcoidosis: disease spectrum and myxovirus resistance protein A expression.

Objectives: Symptomatic myopathy in sarcoidosis patients is not always due to sarcoid myopathy (ScM). We investigated the clinical and pathological spectrum including myxovirus resistance protein A (MxA) expression among sarcoidosis patients.

Methods: We reviewed the Mayo Clinic database (May 1980-December 2020) to identify sarcoidosis patients with myopathic symptoms and pathological evidence of myopathy.

Granulomatous myopathy: Sarcoidosis and beyond.

Non-necrotizing granulomatous inflammation is a rare but easily recognized histopathological finding in skeletal muscle biopsy. A limited number of diseases are known to be associated with non-necrotizing granulomatous myopathy. Once identified, a careful evaluation for evidence of extramuscular granulomatosis and other signs suggestive of sarcoidosis is warranted as about half of the patients have sarcoid myopathy.

Utility of Carpal Tunnel Release and Ulnar Decompression in CMT1A and HNPP.

Introduction/aims: Carpal and cubital tunnel syndrome (CTS, CuTS) are common among patients with hereditary neuropathy with liability to pressure-palsies (HNPP) and Charcot-Marie-Tooth type 1A (CMT1A) and may impact quality of life. We aimed to evaluate the utility of nerve decompression surgeries in these patients.

Methods: Medical records were reviewed for patients with PMP22 mutations confirmed in Mayo Clinic laboratories from January 1999 to December 2020, who had CTS and CuTS and underwent surgical decompression.

A novel missense HNRNPA1 variant in the PY-NLS domain in a patient with late-onset distal myopathy.

Pathogenic HNRNPA1 variants underlying myopathy have been reported only in the prion-like domain of the heterogenous nuclear ribonucleoproteins A1, while two variants in the nuclear localization (PY-NLS) domain were described in ALS. Here we report a 61-year-old man who presented with 1-year history of bilateral foot drop without Paget disease or dementia. Examination revealed severe asymmetric distal weakness, predominantly affecting tibialis anterior and toe extensors.

Neuropathy associated with IgA monoclonal Gammopathy. A harbinger of AL amyloidosis.

Peripheral neuropathy is seen in 15% of patients with IgA monoclonal gammopathy. Treatment and prognosis of dysproteinemic neuropathy is usually guided by the underlying plasma cell disorders, which could be either benign or malignant. The true incidence of hematologic malignancy in patients with neuropathy associated with IgA monoclonal gammopathy is not known.

Neuromuscular ultrasound findings in carpal tunnel syndrome with symptoms mainly in the nondominant hand.

Background: Carpal tunnel syndrome (CTS) may be associated with structural lesions or anatomical variations at the wrist, especially in patients whose symptoms are more severe in, or limited to, the nondominant hand. The aims of this study were to identify the type and frequency of structural abnormalities and anatomical variations, and to demonstrate the contribution of ultrasound in this subgroup of CTS patients.

Methods: A retrospective chart review was performed on all patients referred to the electromyography laboratory who fulfilled the diagnostic criteria for CTS and who underwent neuromuscular ultrasound.

Are We Overlooking Stroke Chameleons? A Retrospective Study on the Delayed Recognition of Stroke Patients.

Background And Purpose: New effective recanalization therapies are currently available for acute ischemic stroke; yet a vast majority of stroke patients are left untreated. The lack of early recognition may be because often times, stroke patients present with atypical manifestations that resemble other conditions (which are referred to as "stroke chameleons"). We set to study the proportion of patients with delayed stroke recognition in a single center.