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Neurophysiol Clin 2022 Apr 14;52(2):174-177. Epub 2022 Mar 14.

Departments of Neurology and Clinical Neurophysiology, Faculty of Medicine, Istanbul University, Istanbul, Turkey.

We investigated how properties of single-fiber action potentials (SFAP) and jitter changed in different recording sites in patients with myopathy and controls. SFAP and jitter were recorded using a disposable single-fiber electrode in the biceps brachii muscle of three patients and controls in two sites: i) near the end-plate zone (EPZ), ii) near the tendon. SFAP and spike duration were longer in patients than in controls. Read More

Neurol India 2022 Jan-Feb;70(1):80-86

Department of Neurology and Clinical Neurophysiology, Istanbul University, Istanbul Faculty of Medicine, Istanbul, Turkey.

Background And Objective: The aim of this study was to evaluate the contribution of extraocular muscle function testing with video-oculography (VOG), which is a noninvasive and easily applicable method of recording eye movement with digital cameras, to the diagnosis of myasthenia gravis (MG) in patients without any clinical eye movement abnormalities.

Methods And Materials: The study included 18 patients prediagnosed with ocular MG: MG Group (N = 7) with abnormal, and non-MG Group (N = 11) with normal single-fiber electromyography. Control group included 50 healthy volunteers. Read More

Eur J Ophthalmol 2022 Feb 15:11206721221077800. Epub 2022 Feb 15.

Neurology Unit, San Filippo Neri Hospital, 18129ASL Roma 1, Rome, Italy.

A 74-years-old man experienced severe diplopia one month after recovery from an uncomplicated SARS-CoV-2 infection. Neurological examination was normal whereas ophthalmological examination showed bilateral exophthalmos with a complex ocular motility disorder characterized by a pseudo-internuclear ophthalmoplegia after fatigue associated to impairment of elevation and infraduction. Antibodies against TSH and acetylcholine receptors were positive; subsequent hormonal tests, ultrasonography of thyroid gland, single fiber electromyography and orbit MRI confirmed the diagnosis of concomitant Graves Disease (GD) and Myasthenia Gravis (MG). Read More

Med Biol Eng Comput 2022 Feb 22;60(2):349-364. Epub 2021 Dec 22.

Department of Electrical and Electronic Engineering. Public, University of Navarra, Campus de Arrosadía s/n., 31006, Pamplona, Spain.

Even under isometric conditions, muscle contractions are associated with some degree of fiber shortening. The effects of muscle shortening on extracellular electromyographic potentials have not been characterized in detail. Moreover, the anatomical, biophysical, and detection factors influencing the muscle-shortening effects have been neither identified nor understood completely. Read More

Neurol Clin 2021 11 3;39(4):1051-1070. Epub 2021 Sep 3.

Neuromuscular Diseases Unit, Department of Neurology, Tel Aviv Sourasky Medical Center, 6 Weizmann Street, Tel Aviv 6423906, Israel.

Please verify edits, "These techniques", or specify. This article reviews advanced electrodiagnostic techniques used to assess for neuromuscular junction disorders, including repetitive nerve stimulation, conventional or concentric-needle single-fiber electromyography (SFEMG), and stimulated SFEMG. These techniques have high sensitivity but limited specificity. Read More

IEEE Trans Biomed Eng 2022 03 18;69(3):1052-1062. Epub 2022 Feb 18.

Objective: Mathematical modelling of surface electromyographic (EMG) signals has been proven a valuable tool to interpret experimental data and to validate signal processing techniques. Most analytical EMG models only consider muscle fibers with specific arrangements. However, the fiber orientation may change along the fiber paths and differ from fiber to fiber. Read More

Neural Plast 2021 13;2021:3045990. Epub 2021 Aug 13.

University of Health and Rehabilitation Sciences, Qingdao, China.

This study presents single-fiber electromyography (EMG) analysis for assessment of paretic muscle changes after stroke. Single-fiber action potentials (SFAPs) were recorded from the first dorsal interosseous (FDI) muscle bilaterally in 12 individuals with hemiparetic stroke. The SFAP parameters, including the negative peak duration and the peak-peak amplitude, were measured and further used to estimate muscle fiber diameter through a model based on the quadratic function. Read More

J Clin Neuromuscul Dis 2021 Sep;23(1):39-42

Department of Neurology, The University of North Carolina at Chapel Hill, Chapel Hill, NC.

Abstract: Muscle-specific kinase (MuSK) antibody is seen in 4%-10% of patients with myasthenia gravis (MG), with 40% of these patients reporting bulbar weakness as the initial symptom. We present the case of a 40-year-old woman with MuSK MG whose only presenting symptom was progressive respiratory insufficiency necessitating BiPAP use 16-24 hours daily. She was unresponsive to treatment for cardiac and pulmonary causes and thus referred to neurology. Read More

Neuropsychiatr Dis Treat 2021 22;17:2063-2071. Epub 2021 Jun 22.

Department of Neurology, Kasr Al Ainy Hospital, Faculty of Medicine, Cairo University, Cairo, Egypt.

Purpose: Much effort has been directed toward studying COVID-19 symptoms; however, the post-COVID-19 phase remains mysterious. The aim of this work was to conduct a clinical and neurophysiological evaluation of physical and mental fatigue in COVID-19 long-haulers and to study whether markers of COVID-19 severity are able to predict the likelihood of developing postinfectious fatigue syndrome (PIFS) in such patients.

Patients And Methods: This case-control study was conducted on 46 COVID-19 long-haulers who met the criteria for PIFS and 46 recovered COVID-19 subjects without any residuals. Read More

Neurol Sci 2021 Oct 3;42(10):4317-4320. Epub 2021 Jun 3.

Division of Neurology, Department of Neurosciences, College of Medicine-Philippine General Hospital, University of the Philippines Manila, Taft Avenue, Ermita, 1000, Manila, Philippines.

We report a 51-year-old male diagnosed with X-linked recessive spinal and bulbar muscular atrophy (SBMA) by genetic testing who presented with 30 years history of progressive proximal and bulbar weakness responsive to cholinesterase inhibitor. Although the anti-acetylcholine receptor antibody (anti-AChR Ab) was negative, the myasthenic state was confirmed by decremental response in repetitive nerve stimulation and increased jitter frequency and blocking in single fiber-electromyography. While myasthenia gravis and SBMA may co-exist independently in an individual having the signs and symptoms of both conditions, the absence of anti-AChR Ab may imply that myasthenia can be an exaggerated activity-induced fatigue or weakness from the latter. Read More

Toxins (Basel) 2021 05 17;13(5). Epub 2021 May 17.

EuroMov DHM, IMT Ales, Univ Montpellier, 34090 Montpellier, France.

Botulinum toxin-A (BoNT-A) blocks acetylcholine release at the neuromuscular junction (NMJ) and is widely used for neuromuscular disorders (involuntary spasms, dystonic disorders and spasticity). However, its therapeutic effects are usually measured by clinical scales of questionable validity. Single-fiber electromyography (SFEMG) is a sensitive, validated diagnostic technique for NMJ impairment such as myasthenia. Read More

Neurology 2021 05;96(19):918-919

(Bologna, Italy).

Neurology 2021 05;96(19):918

(Buffalo).

Neurobiol Aging 2021 08 12;104:32-41. Epub 2021 Mar 12.

Department of Neurology, Neuromuscular Division, The Ohio State University Wexner Medical Center, Columbus, OH, USA; Department of Physical Medicine and Rehabilitation, The Ohio State University Wexner Medical Center, Columbus, OH, USA; Department of Neuroscience, The Ohio State University Wexner Medical Center, Columbus, OH, USA; Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, Columbus, OH, USA. Electronic address:

Sarcopenia, or age-related loss of muscle mass and strength, is an important contributor to loss of physical function in older adults. The pathogenesis of sarcopenia is likely multifactorial, but recently the role of neurological degeneration, such as motor unit loss, has received increased attention. Here, we investigated the longitudinal effects of muscle hypertrophy (via overexpression of human follistatin, a myostatin antagonist) on neuromuscular integrity in C57BL/6J mice between the ages of 24 and 27 months. Read More

Neurophysiol Clin 2021 Oct 5;51(5):466-479. Epub 2021 May 5.

Department of Neurology, Medical University of Warsaw, Banacha 1A Str., 02-097 Warsaw, Poland.

Objectives: The aim was to improve the identification of potentials recorded using single fiber electromyography (SFEMG) contaminated by potentials from other muscle fibers, which might affect measured jitter value, by defining more selective criteria of single fiber potential (SFP) discrimination. We were looking for solutions suitable for automatization.

Methods: Standard parameters characterizing SFP and their combinations were analyzed to define an analytical discriminating function able to verify if potentials recorded using SFEMG are due to single fiber or due to two (or more) fibers. Read More

Geroscience 2021 06 24;43(3):1265-1281. Epub 2021 Apr 24.

Division of Neuromuscular Diseases, Department of Neurology, The Ohio State University Wexner Medical Center, 1060 Carmack Road, Room 207, Columbus, OH, 43210, USA.

Pathological age-related loss of skeletal muscle strength and mass contribute to impaired physical function in older adults. Factors that promote the development of these conditions remain incompletely understood, impeding development of effective and specific diagnostic and therapeutic approaches. Inconclusive evidence across species suggests disruption of action potential signal transmission at the neuromuscular junction (NMJ), the crucial connection between the nervous and muscular systems, as a possible contributor to age-related muscle dysfunction. Read More

Neurol Clin Pract 2021 Apr;11(2):97-104

Department of Neurology (LPB), Centro Hospitalar Universitário de São João, Porto, Portugal; and Wellcome Centre for Mitochondrial Research (YSN, GSG, AMS, RM, RWT, DMT), Translational and Clinical Research Institute (RGW), Newcastle University, Newcastle upon Tyne, United Kingdom.

Objective: To determine the prevalence of neuromuscular junction (NMJ) abnormalities in patients with mitochondrial disease.

Methods: Eighty patients with genetically proven mitochondrial disease were recruited from a national center for mitochondrial disease in the United Kingdom. Participants underwent detailed clinical and neurophysiologic testing including single-fiber electromyography. Read More

Muscle Nerve 2021 06 31;63(6):885-889. Epub 2021 Mar 31.

Department of Neurology, Graduate School of Medicine, Chiba University, Chiba, Japan.

Introduction: In this study we aimed to investigate the dispersion of mean consecutive difference (MCD) of concentric needle jitter studies of patients with myasthenia gravis (MG) and its effect on diagnostic sensitivity for MG.

Methods: One hundred fifty-three patients, including 76 patients with MG and 77 controls with possible MG who later received another diagnosis, underwent stimulated concentric needle jitter studies of the frontalis muscle. MCD mean, standard deviation (SD), and coefficient of variation (CV) were calculated. Read More

Neuropediatrics 2021 12 11;52(6):462-468. Epub 2021 Mar 11.

Department of Paediatrics, Copenhagen University Hospital, Rigshospitalet, Denmark.

Aim: The diagnostic workup in patients with delayed motor milestones suspected of having either myopathy or a congenital myasthenic syndrome is complex. Our hypothesis was that performance of a muscle biopsy and neurophysiology including stimulated single-fiber electromyography during an anesthetic procedure, combined with genetic testing has a high diagnostic quality.

Materials And Methods: Clinical and paraclinical data were retrospectively collected from 24 patients aged from 1 month to 10 years (median: 5. Read More

Eur Arch Otorhinolaryngol 2021 Jul 10;278(7):2387-2395. Epub 2021 Mar 10.

Department of Otorhinolaryngology, Division of Phoniatrics and Speech Language Therapy, Medical University of Vienna/Vienna General Hospital, Waehringer Guertel 18-20, 1090, Vienna, Austria.

Purpose: In clinical practice, laryngo(strobo)scopy (LS) is still mainly used for diagnostics and management of unilateral vocal fold paralysis (UFVP), although only laryngeal electromyography (LEMG) can provide information on causes of vocal fold immobility, especially on possible synkinetic reinnervation after recurrent laryngeal nerve (RLN) injury. The goal of this retrospective study was the evaluation whether signs of synkinetic reinnervation in LS can be objectified in comparison to LEMG data.

Methods: Between 1/2015 and 2/2018, 50 patients with laryngostroboscopically suspected UVFP received routine LEMG examination. Read More

Acta Neurol Belg 2022 Apr 5;122(2):337-344. Epub 2021 Feb 5.

Department of Neurology, Ege University, 35000, Bornova, Izmir, Turkey.

Conversion to generalized myasthenia gravis (GMG) within the first 2 years has been reported in 18-85% of patients with ocular myasthenia gravis (OMG). The aim of the study was to investigate the risk factors for generalization in patients with OMG admitted to a neuro-ophthalmology clinic and to determine if there were differences between patients with GMG with predominant bulbar (GMG-B) or extremity muscle (GMG-E) involvement according to the 6th and 24th-month Myasthenia Gravis Foundation of America classification ranks. Patients with OMG who were followed-up for at least 24 months were retrospectively analyzed. Read More

Clin Neurophysiol Pract 2021 17;6:36-40. Epub 2020 Dec 17.

Department of Neurology, Division of Clinical Neurophysiology, University of Iowa Health Center, 200 Hawkins Drive, Iowa City, IA 52242, USA.

Objective: We report a case of sustained atypical myokymia associated with short bursts of neuromyotonic discharges involving the abductor pollicis brevis (APB) muscle and describe a useful way of detecting a focal slowing involving a small number of median nerve motor fibers with a concentric needle using the filter setting for single fiber electromyography (EMG).

Methods And Results: A 62-year-old woman developed right thumb twitches at regular interval of 1.7-3. Read More

J Neuromuscul Dis 2021 ;8(2):295-298

Department of Neurology, University of Athens, Eginition Hospital, Athens, Greece.

Fatigability is the hallmark of myasthenia gravis (MG). It is not clear, however, whether there is an analogous increase in jitter during the course of a single fiber electromyography (SFEMG) session. The individual jitter values of all potentials of 76 normal and 44 myasthenic orbicularis oculi muscles were assigned a rank number according to their temporal order in which they were collected and linear regression was performed to determine if the slope of the regression line was significantly different from zero. Read More

J Neurosci Methods 2021 03 24;351:109045. Epub 2020 Dec 24.

Department of Neurology, University of Minnesota, Minneapolis, MN, United States.

Background: In clinical practice, small myelinated sensory fibers, Aδ-fibers, conveying mainly pain and temperature sensations, cannot be examined with available nerve conduction study techniques. Currently, these fibers can only be examined with experimental or very specialized and not commonly available nerve conduction techniques, or only indirectly with cerebral evoked potentials.

New Method: This study uses equipment and methods available in clinical neurophysiology laboratories to record from human sensory nerves ≥1000 averaged responses to focal, non-painful stimuli applied by a special electrode to epidermal nerves. Read More

Front Neurol 2020 13;11:600680. Epub 2020 Nov 13.

Department of Clinical Neurophysiology, Institute of Neurosciences, Uppsala University, Uppsala, Sweden.

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. Read More

Muscle Nerve 2020 11 13;62(5):593-596. Epub 2020 Aug 13.

Department of Neurology, University Hospital of Halle, Halle (Saale), Germany.

Background: The time interval between two potential components of the same motor unit potential (MUP) is measured for jitter analysis. Enhanced jitter is generally thought to result from impaired neuromuscular transmission as occurs in myasthenia gravis or during reinnervation.

Methods: Within a database of conventional video-electromyography (EMG) recordings 4 MUP with peculiar jitter patterns were identified. Read More

Neuromuscul Disord 2020 11 14;30(11):897-903. Epub 2020 Oct 14.

Department of Neurology, Faculdade de Medicina da Universidade de São Paulo (FMUSP), Av. Dr. Enéas Carvalho Aguiar 255, 05403-900 São Paulo SP, Brazil. Electronic address:

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). Read More

Am J Phys Med Rehabil 2021 07;100(7):e98-e100

From the Western University, Clinical Neurological Sciences, London, Ontario, Canada.

Abstract: We present a case of chronic, progressive proximal weakness with dysautonomia and hyporeflexia/areflexia ultimately diagnosed with Lambert-Eaton myasthenic syndrome. An approach to neuroanatomical localization is discussed leading to the appropriate selection of electrodiagnostic studies. The electrophysiologic triad of Lambert-Eaton myasthenic syndrome is demonstrated with diffusely reduced motor amplitudes, decrement with low-frequency repetitive nerve stimulation, and increment of motor amplitudes after maximum voluntary contraction. Read More

Muscle Nerve 2021 02 26;63(2):217-224. Epub 2020 Oct 26.

Department of Neurology, University of Athens, Eginition Hospital, Athens, Greece.

Background: Little is known about how different outlier estimation methods affect cutoff limits for outliers in single fiber electromyography.

Methods: We compared in a prospective fashion the established 18th jitter value (18thjv) method to three, whole-distribution based, outlier detection methods: the interquartile range (IQR), the log-normal, and the Z-score method. The reference limits were probed in a normal cohort and in myasthenia gravis (MG) patients. Read More

Muscle Nerve 2021 01 24;63(1):113-116. Epub 2020 Oct 24.

Department of Neurology, University of Alabama at Birmingham, Birmingham, Alabama, USA.

Background: The extrapolated reference values procedure (E-Ref) was used to compare data from a single institution with the recently published reference value (RV) for concentric electrode jitter.

Methods: Data from voluntarily activated concentric needle jitter studies in the frontalis muscle were obtained using retrospective chart review. All measured signals were reviewed for acceptable quality. Read More