Unraveling calcium dysregulation and autoimmunity in immune mediated rippling muscle disease.

Rippling Muscle Disease (RMD) is a rare skeletal myopathy characterized by abnormal muscular excitability manifesting with wave-like muscle contractions and percussion-induced muscle mounding. Hereditary RMD is associated with caveolin-3 or cavin-1 mutations. Recently, we identified cavin 4 autoantibodies as a biomarker of immune-mediated RMD (iRMD), though the underlying disease-mechanisms remain poorly understood.

Compound Muscle Action Potential and Myosin-Loss Pathology in Patients With Critical Illness Myopathy: Correlation and Prognostication.

Background And Objectives: Prolonged compound muscle action potential (CMAP) duration and preferential loss of myosin are considered the diagnostic hallmarks of critical illness myopathy (CIM); however, their correlation and prognostic values have not been studied. We aimed to investigate the correlation between CMAP duration and myosin loss and their effect on mortality by comparing between patients with CIM with and without myosin loss.

Methods: We searched the Mayo Clinic Electromyography Laboratory databases (1986-2021) for patients diagnosed with CIM on the basis of prolonged distal CMAP durations (>15 msec in fibular motor nerve studies recording over the tibialis anterior or >8 msec in other motor nerves) and needle EMG findings compatible with myopathy.

The utility of electrodiagnostic testing in unprovoked rhabdomyolysis in the era of next-generation sequencing.

Introduction/aims: Rhabdomyolysis is an etiologically heterogeneous, acute necrosis of myofibers characterized by transient marked creatine kinase (CK) elevation associated with myalgia, muscle edema, and/or weakness. The study aimed to determine the role of electrodiagnostic (EDX) testing relative to genetic testing and muscle biopsy in patients with unprovoked rhabdomyolysis in identifying an underlying myopathy.

Methods: EDX database was reviewed to identify unprovoked rhabdomyolysis patients who underwent EDX testing between January 2012 and January 2022.

Electrodiagnostic and ultrasound evaluation of respiratory weakness.

Phrenic nerve conduction studies (NCSs) and needle electromyography (EMG) can provide important information on the underlying pathophysiology in patients presenting with unexplained shortness of breath, failure to wean from the ventilator, or consideration of phrenic nerve pacemaker implantation. However, these techniques are often technically challenging, require experience, can lack sensitivity and specificity, and, in the case of diaphragm EMG, involve some degree of risk. Diagnostic high-resolution ultrasound has been introduced in recent years as an adjuvant technique readily available at the bedside that can increase the overall sensitivity and specificity of the neurophysiologic evaluation of respiratory symptoms.

Peripheral Nervous, Hepatic, and Gastrointestinal Endpoints for AL Amyloidosis Clinical Trials: Report from the Amyloidosis Forum Multi-organ System Working Group.

Systemic immunoglobulin light chain (AL) amyloidosis is a heterogeneous rare disease driven by a destructive monoclonal gammopathy and typified by misfolded immunoglobulin light and/or heavy chains which aggregate and deposit in organs as insoluble amyloid fibrils. Disease heterogeneity is driven by the degree of multi-systemic involvement; cardiac, renal, neurological, and gastrointestinal (GI) systems are affected to varying degrees in different patients. While prognosis is primarily driven by hematologic response to treatment and outcomes associated with cardiac events and overall survival, the involvement of the peripheral nervous, hepatic, and GI systems can also have a significant impact on patients.

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.

Composite nerve conduction scores and signs for diagnosis and somatic staging of diabetic polyneuropathy: Mid North American ethnic cohort survey.

Introduction/aims: In the Diabetes Control and Complications Trial (DCCT), the minimal nerve conduction (NC) criterion for diabetic sensorimotor polyneuropathy (DSPN) was abnormality of NC in more than one peripheral nerve without specifying the attributes of NCs to be evaluated. In the present study, we assess individual and composite scores of NCs meeting the DCCT criterion and signs for improved diagnosis and assessment of DSPN severity.

Methods: Evaluated were 13 attributes and 6 composite NC scores and signs and symptoms in 395 healthy subjects (HS) and 388 persons with diabetes (DM).

Identification of Caveolae-Associated Protein 4 Autoantibodies as a Biomarker of Immune-Mediated Rippling Muscle Disease in Adults.

Importance: Immune-mediated rippling muscle disease (iRMD) is a rare myopathy characterized by wavelike muscle contractions (rippling) and percussion- or stretch-induced muscle mounding. A serological biomarker of this disease is lacking.

Objective: To describe a novel autoantibody biomarker of iRMD and report associated clinicopathological characteristics.

Procedures for obtaining muscle physiology parameters during a gracilis free-functioning muscle transfer in adult patients with brachial plexus injury.

A complete understanding of muscle mechanics allows for the creation of models that closely mimic human muscle function so they can be used to study human locomotion and evaluate surgical intervention. This includes knowledge of muscle-tendon parameters required for accurate prediction of muscle forces. However, few studies report experimental data obtained directly from whole human muscle due to the invasive nature of these experiments.

Variable differences of nerve conduction amplitudes versus velocities and distal latencies of healthy subjects assessed in ethnic cohorts.

Unlabelled: Variable differences of nerve conduction amplitudes vs velocities and distal latencies (DLs) of healthy subjects assessed in ethnic cohorts.

Introduction/aims: The variables affecting reference compound muscle (CMAP) and sensory nerve action potential (SNAP) amplitudes as compared to ones affecting conduction velocities and DLs have not been adequately evaluated in previous studies. In this report, this subject is studied in healthy subject cohorts mainly of Northern European extraction, Northern Plains Indians, and Latinos.

Intramuscular pressure of human tibialis anterior muscle detects age-related changes in muscle performance.

Intramuscular pressure (IMP) reflects forces produced by a muscle. Age is one of the determinants of skeletal muscle performance. The present study aimed to test whether IMP mirrors known age-related muscular changes.

mNIS+7 and lower limb function in inotersen treatment of hereditary transthyretin-mediated amyloidosis.

Introduction: Inotersen, an antisense oligonucleotide inhibitor of transthyretin (TTR) protein production, demonstrated significant benefit versus placebo in the modified Neuropathy Impairment Score (NIS) +7 neurophysiologic tests (mNIS+7) in patients with hereditary TTR-mediated amyloidosis (hATTR) with polyneuropathy. This analysis assessed the mNIS+7 components by anatomic location and the lower limb function (LLF) test.

Methods: Adults with hATTR in the NEURO-TTR trial (NCT01737398) were randomly assigned to receive weekly doses of subcutaneous inotersen 300 mg or placebo for 65 weeks.

Neuropathy symptom and change: Inotersen treatment of hereditary transthyretin amyloidosis.

Introduction: Hereditary transthyretin-mediated amyloidosis (hATTR) manifests as multisystem dysfunction, including progressive polyneuropathy. Inotersen, an antisense oligonucleotide, improved the course of neuropathic impairment in patients with hATTR in the pivotal NEURO-TTR study (NCT01737398). To determine inotersen's impact on symptoms and patients' neuropathy experience, we performed a post hoc analysis of the Neuropathy Symptoms and Change (NSC) score.

AANEM - IFCN glossary of terms in neuromuscular electrodiagnostic medicine and ultrasound.

Modern neuromuscular electrodiagnosis (EDX) and neuromuscular ultrasound (NMUS) require a universal language for effective communication in clinical practice and research and, in particular, for teaching young colleagues. Therefore, the AANEM and the IFCN have decided to publish a joint glossary as they feel the need for an updated terminology to support educational activities in neuromuscular EDX and NMUS in all parts of the world. In addition NMUS has been rapidly progressing over the last years and is now widely used in the diagnosis of disorders of nerve and muscle in conjunction with EDX.

AANEM - IFCN Glossary of Terms in Neuromuscular Electrodiagnostic Medicine and Ultrasound.

Modern neuromuscular electrodiagnosis (EDX) and neuromuscular ultrasound (NMUS) require a universal language for effective communication in clinical practice and research and, in particular, for teaching young colleagues. Therefore, the AANEM and the IFCN have decided to publish a joint glossary as they feel the need for an updated terminology to support educational activities in neuromuscular EDX and NMUS in all parts of the world. In addition NMUS has been rapidly progressing over the last years and is now widely used in the diagnosis of disorders of nerve and muscle in conjunction with EDX.

Development of measures of polyneuropathy impairment in hATTR amyloidosis: From NIS to mNIS + 7.

Hereditary transthyretin-mediated amyloidosis (hATTR amyloidosis) is a rare, life-threatening disease, caused by point mutations in the transthyretin gene. It is a heterogeneous, multisystem disease with rapidly progressing polyneuropathy (including sensory, motor, and autonomic impairments) and cardiac dysfunction. Measures used to assess polyneuropathy in other diseases have been tested as endpoints in hATTR amyloidosis clinical trials (i.

Intramuscular Pressure of Human Tibialis Anterior Muscle Reflects Muscular Activity.

Intramuscular pressure (IMP) is the fluid hydrostatic pressure generated within a muscle and reflects the mechanical forces produced by a muscle. By providing accurate quantification of interstitial fluid pressure, the measurement of IMP may be useful to detect changes in skeletal muscle function not identified with established techniques. However, the relationship between IMP and muscle activity has never been studied in healthy human muscles.

Plantar Ulcers and Neuropathic Arthropathies: Associated Diseases, Polyneuropathy Correlates, and Risk Covariates.

Objective: To evaluate the associated diseases, polyneuropathy correlates, and risk covariates of neuropathic plantar ulcers (PUs) and neuropathic arthropathies (NAs).

Design: The authors conducted a retrospective, observational study over 3.5 years of 69 patients with neuropathy, NA, or PU seen in a wound clinic who also had a comprehensive neurologic evaluation and neurophysiologic testing.

Neuromuscular transmission defects in myopathies: Rare but worth searching for.

Introduction: Decremental responses in repetitive nerve stimulation have been reported in a few hereditary myopathies. We examined the frequency of decrement in a cohort of myopathy patients.

Methods: We reviewed all patients referred for myopathy who underwent repetitive nerve stimulation between January 2007 and May 2017.

Muscle Biopsy and Electromyography Correlation.

In myopathies, the correlation of individual electromyographic and histopathologic findings remains poorly explored, as most previous studies have focused on the ability of muscle biopsy and electromyography to distinguish the neuropathic vs. myopathic nature of the underlying neuromuscular disease. We identified 100 patients who had a muscle biopsy and electromyography performed on identical muscles.