Electrophysiological evaluation of the neuromuscular junction: a brief review.

The nerve terminal and muscle membrane compose the neuromuscular junction. After opening the voltage-gated calcium channels, action potentials from the motor axons provoke a cascade for the acetylcholine release from synaptic vesicles to the synaptic cleft, where it binds to its receptor at the muscle membrane for depolarization. Low amplitude compound muscle action potential typically presents in presynaptic disorders, increasing by more than 100% after a 10-second effort in the Lambert-Eaton myasthenic syndrome and less in botulism.

A case of mitochondrial DNA depletion syndrome type 11 - expanding the genotype and phenotype.

Mitochondrial DNA depletion syndrome type 11 (MTDPS11) is caused by pathogenic variants in MGME1 gene. We report a woman, 40-year-old, who presented slow progressive drop eyelid at 11-year-old with, learning difficulty and frequent falls. Phisical examination revealed: mild scoliosis, elbow hyperextensibility, flat feet, chronic progressive external ophthalmoplegia with upper eyelid ptosis, diffuse hypotonia, and weakness of arm abduction and neck flexion.

Muscle fiber conduction velocity revisited: A new approach to an ancient technique.

The aim of this study was to measure the muscle fiber conduction velocity (MFCV) in the tibialis anterior muscle in healthy subjects. A total of 36 subjects matched for age and sex were studied. The MFCV was measured with a concentric needle by intramuscular monopolar needle electrical activation at a distance of 50 mm.

Concentric needle jitter: Reference values in stimulated muscle.

Calculating the reference values for jitter parameters utilizing a disposable concentric needle have been already done for the most often tested muscles. Jitter, expressed as the mean consecutive difference (MCD), was measured in the (TA), not routinely tested muscle. Jitter measurement was taken using the intramuscular microaxonal stimulation technique in 32 healthy subjects.

Single fiber electromyography and measuring jitter with concentric needle electrodes.

This monograph contains descriptions of the single fiber electromyography (SFEMG) method and of the more recently implemented method of recording jitter with concentric needle electrodes (CNEs). SFEMG records action potentials from single muscle fibers (SFAPs), which permits measuring fiber density (FD), a sensitive measure of reinnervation, and jitter, a sensitive measure of abnormal neuromuscular transmission (NMT). With voluntary activation, jitter is measured between two SFAPs with acceptable amplitude and rise time.

Congenital myasthenic syndrome: Correlation between clinical features and molecular diagnosis.

Objectives: To present phenotype features of a large cohort of congenital myasthenic syndromes (CMS) and correlate them with their molecular diagnosis.

Methods: Suspected CMS patients were divided into three groups: group A (limb, bulbar or axial weakness, with or without ocular impairment, and all the following: clinical fatigability, electrophysiology compatible with neuromuscular junction involvement and anticholinesterase agents response), group B (limb, bulbar or axial weakness, with or without ocular impairment, and at least one of additional characteristics noted in group A) and group C (pure ocular syndrome). Individual clinical findings and the clinical groups were compared between the group with a confirmed molecular diagnosis of CMS and the group without molecular diagnosis or with a non-CMS molecular diagnosis.

Concentric Needle Jitter in 97 Myasthenia Gravis Patients.

To estimate the jitter parameters (single-fiber electromyography) in myasthenia gravis patients mostly by electrical activation in , and muscles using a concentric needle electrode. Between 2009 and 2019, a total of 97 myasthenia gravis patients, 52 male, and mean age 54 years were included. Any abnormal jitter parameter in individual muscles was 90.

Electrophysiological study of neuromuscular junction in congenital myasthenic syndromes, congenital myopathies, and chronic progressive external ophthalmoplegia.

This study was designed to analyze the sensitivity, specificity, and accuracy of jitter parameters combined with repetitive nerve stimulation (RNS) in congenital myasthenic syndrome (CMS), chronic progressive external ophthalmoplegia (CPEO), and congenital myopathies (CM). Jitter was obtained with a concentric needle electrode during voluntary activation of the Orbicularis Oculi muscle in CMS (n = 21), CPEO (n = 20), and CM (n = 18) patients and in controls (n = 14). RNS (3 Hz) was performed in six different muscles for all patients (Abductor Digiti Minimi, Tibialis Anterior, upper Trapezius, Deltoideus, Orbicularis Oculi, and Nasalis).

Jitter evaluation in denervation and reinnervation in 32 cases of chronic radiculopathy.

Objective: To measure the jitter parameters in muscles with denervation/reinnervation in 32 chronic radiculopathy cases.

Methods: Measurements were done in chronic denervated muscles by voluntary and electrical activation using a concentric needle electrode.

Results: Mean jitter was abnormal in 87.

Jitter Evaluation in Distant and Adjacent Muscles after Botulinum Neurotoxin Type A Injection in 78 Cases.

To study the jitter parameters in the distant (DM) and the adjacent muscle (AM) after botulinum neurotoxin type A (BoNT/A) injection in 78 patients, jitter was measured by voluntary activation in DM ( = 43), and in AM ( = 35). Patients were receiving BoNT/A injections as a treatment for movement disorders. Mean age 65.

Guidelines for single fiber EMG.

This document is the consensus of international experts on the current status of Single Fiber EMG (SFEMG) and the measurement of neuromuscular jitter with concentric needle electrodes (CNE - CN-jitter). The panel of authors was chosen based on their particular interests and previous publications within a specific area of SFEMG or CN-jitter. Each member of the panel was asked to submit a section on their particular area of interest and these submissions were circulated among the panel members for edits and comments.

Problems in Comparing Jitter Values Obtained with Voluntary Activation and Electrical Stimulation.

Comparing results from jitter studies performed with voluntary and electrical activation is difficult to perform quantitatively, particularly in complex signals as seen in reinnervation. High jitter values in individual spikes in these multispike signals can be missed with both activation methods, which introduces a bias towards more normal values.With voluntary activation, triggering on a spike from an abnormal end-plate in multispike potentials will overestimate individual jitter values and the number of abnormal jitter values.

Pitfalls and errors in measuring jitter.

The safety factor of neuromuscular transmission can be assessed by measuring the neuromuscular jitter, which reflects the time variability of processes in the motor end-plate. Jitter is increased in any condition with disturbed end-plate function, such as myasthenic conditions and ongoing reinnervation. Jitter is increasingly being measured with concentric needle (CN) electrodes, which are more prone to artefacts than single fiber EMG recordings.

Peripheral nerve injuries: A retrospective survey of 1124 cases.

Background: Peripheral nerve injuries (PNIs) remain an important health problem often leading to severe motor disabilities predominantly in the younger population.

Objective: To analyze our experience of clinical and electrodiagnostic evaluation (EDX) of PNIs over a 26-year period.

Materials And Methods: Between 1989 and 2014, 1124 consecutive patients with 1418 PNIs were referred for clinical as well as EDX evaluation.

Diagnostic accuracy of concentric needle jitter in myasthenia: Prospective study.

Introduction: The aim of this study was to estimate jitter parameters in the orbicularis oculi muscle using a concentric needle electrode (CNE) in patients with myasthenia gravis (MG) and to determine its diagnostic accuracy for jitter analysis (CNEMG-jitter).

Methods: CNEMG-jitter was performed in 20 healthy subjects and 33 MG patients using the voluntary contraction technique. Receiver operating characteristic (ROC) curves were constructed to determine cut-off points with the best sensitivity/specificity combination for jitter analysis.

Time perception and age.

Unlabelled: Our internal clock system is predominantly dopaminergic, but memory is predominantly cholinergic. Here, we examined the common sensibility encapsulated in the statement: "time goes faster as we get older".

Objective: To measure a 2 min time interval, counted mentally in subjects of different age groups.

[MHC class I antigens, CD4 and CD8 expressions in polymyositis and dermatomyositis].

Objective: To analyze the frequencies of the expression of major histocompatibility complex class I (MHC-I) antigens, and CD4 and CD8 cells in skeletal muscle in polymyositis (PM) and dermatomyositis (DM).

Methods: This was a retrospective study of 34 PM cases, 8 DM cases, and 29 control patients with non-inflammatory myopathies.

Results: MHC-I antigens were expressed in the sarcolemma and/or sarcoplasm in 79.

Stimulated jitter with concentric needle in 42 myasthenia gravis patients.

Objective: To estimate jitter parameters in myasthenia gravis in stimulated frontalis and extensor digitorum muscles using the concentric needle electrode.

Methods: Forty-two confirmed myasthenia gravis patients, being 22 males (aged 45.6±17.

Concentric needle jitter on voluntary activated frontalis in 20 healthy subjects.

Introduction: Normative data for jitter parameters using a disposable concentric needle have been described in a few studies.

Methods: Jitter, expressed as the mean consecutive difference (MCD), was measured in the frontalis muscle in 20 subjects by voluntary contraction.

Results: Mean MCD for individual studies (20, gaussian), all potentials (400, non-gaussian), and 18th highest value (20, gaussian) were 19.

NINJURIN1 single nucleotide polymorphism and nerve damage in leprosy.

Unlabelled: Leprosy, a chronic infectious disease caused by Mycobacterium leprae, can damage the peripheral nervous system and represents one of the leading causes of nontraumatic neuropathy in some developing countries. The NINJURIN1 is a cell adhesion molecule that provides suitable substrates for repair of Schwann cells after peripheral nerve injury. The single nucleotide polymorphism NINJ1, is the result of a transversion of an adenine to a nucleotide polymorphic cytokine (A→C), responsible for an amino acid exchange of asparagine to alanine at position 110 of the protein (asp110ala).

Concentric needle jitter in stimulated frontalis in 20 healthy subjects.

Normative data for jitter parameters using a disposable concentric needle have been presented in a few studies. Jitter, expressed as the mean consecutive difference (MCD), was measured in the frontalis muscle in 20 subjects by percutaneous bar stimulation of the temporal nerve branch. The mean MCD for individual studies (20) and for all potentials (600) were 16.

Concentric needle jitter on stimulated frontalis and extensor digitorum in 20 myasthenia gravis patients.

Introduction: Our objective was to study jitter parameters using a concentric needle electrode (CNE) in the extensor digitorum (ED) and frontalis (FR) muscles.

Methods: Twenty myasthenia gravis (MG) patients, mean age 44.5 years, were studied.

Concentric needle jitter on stimulated Orbicularis Oculi in 50 healthy subjects.

Objectives: The aim of this study was to estimate the jitter parameters in healthy controls in stimulated Orbicularis Oculi (OOc) muscle using concentric needle electrode (CNE).

Methods: Fifty healthy subjects, 13 males and 37 females (21-56 years, mean age of 38±9.2 years) were studied.

Carpal tunnel syndrome in the elderly: nerve conduction parameters.

Objective: To establish nerve conduction parameters for carpal tunnel syndrome (CTS) electrodiagnosis in the elderly.

Method: Thirty healthy subjects (65-86 years), 9 male and 21 female, were studied. Routine median and ulnar sensory and motor nerve conduction studies, median mixed palmar latency, comparative latency techniques median to ulnar (sensory, mixed and motor lumbrical-interossei), median to radial (sensory), and combined sensory index (CSI) were performed in both hands.

Pompe disease in a Brazilian series: clinical and molecular analyses with identification of nine new mutations.

Pompe disease (glycogen storage disease type II or acid maltase deficiency) is an inherited autosomal recessive deficiency of acid alpha-glucosidase (GAA), with predominant manifestations of skeletal muscle weakness. A broad range of studies have been published focusing on Pompe patients from different countries, but none from Brazil. We investigated 41 patients with either infantile-onset (21 cases) or late-onset (20 cases) disease by muscle pathology, enzyme activity and GAA gene mutation screening.