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Neurobiol Aging 2021 Mar 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 May 4. Epub 2021 May 4.

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 Apr 24. 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 Mar 21. Epub 2021 Mar 21.

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 Mar 11. 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 Mar 10. 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

Arthritis Rheumatol 2021 Mar 7. Epub 2021 Mar 7.

Department of Health Services Research, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.

We thank Dr. Suzuki for his comments. His personal and firsthand experience expands on our increasing knowledge of immune checkpoint inhibitor (ICI)-induced myositis and ICI-myasthenia gravis (MG) from a clinical and laboratory perspective. Read More

Acta Neurol Belg 2021 Feb 5. 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

J Neuroophthalmol 2021 Mar;41(1):128-134

In this issue of Journal of Neuro-Ophthalmology, M. Tariq Bhatti, MD, and Mark L. Moster, MD will discuss the following 6 articles: Giannoccaro MP, Paolucci M, Zenesini C, Di Stasi V, Donadio V, Avoni P, Liguori R. 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 Mar 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

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

Clin Neurophysiol Pract 2020 14;5:165-172. Epub 2020 Aug 14.

Fellows in Neuromuscular Diseases and Eletrectromyography, Faculdade Estadual Medicina Sao Jose do Rio Preto (FAMERP), 15090-000 Sao Jose do Rio Preto, Sao Paulo, Brazil.

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. Read More

Front Neurol 2020 13;11:861. Epub 2020 Aug 13.

Department of Ophthalmology, University Hospital Zurich, University of Zurich, Zurich, Switzerland.

Timely and accurate diagnosis of myasthenia gravis, particularly in patients with fluctuating, isolated ocular involvement, remains challenging. Serological antibody testing and repetitive nerve stimulation of peripheral muscles usually have low sensitivity in these patients. Edrophonium testing may cause adverse events, single-fiber electromyography (SFEMG) is time-consuming and both tests are often unavailable outside specialized institutions. Read More

Toxins (Basel) 2020 08 27;12(9). Epub 2020 Aug 27.

Departamento de Ciências Neurológicas, Fundação Faculdade Regional de Medicina São José do Rio Preto (FUNFARME), São José do Rio Preto SP 15090-000, Brazil.

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. Read More

Neurology 2020 09 11;95(13):e1800-e1806. Epub 2020 Aug 11.

From the Dipartimento di Scienze Biomediche e Neuromotorie (M.P.G., P.A., R.L.), Università di Bologna; IRCCS Istituto delle Scienze Neurologiche di Bologna (M.P.G., C.Z., V.D.S., V.D., P.A., R.L.); UO Neurosonologia e Cefalee (M.P.), Università Campus Bio-Medico, Rome; and UO Neurologia (M.P.), Ospedale M. Bufalini, Cesena, AUSL Romagna, Italy.

Objective: To compare the diagnostic accuracy of ice pack test (IPT) and single-fiber EMG (SF-EMG) in patients with suspected ocular myasthenia (OM) presenting with ptosis.

Methods: We studied consecutive patients referred for the clinical suspicion of OM. Patients underwent IPT and stimulated SF-EMG on the orbicularis oculi muscle. Read More

Neurol Genet 2020 Aug 30;6(4):e468. Epub 2020 Jun 30.

theNeurogenomics Division (S.S., J.K., K.R., N.B., C.B., A.L.S., M.R., R.R., M.D.B., A.M.C., M.J.H, V.N., S.R.), Translational Genomics Research Institute, Center for Rare Childhood Disorders, Phoenix, AZ; Fulgent Genetics (S.P.S.), Temple City, CA; Department of Neurology (P.B.S.), University of California Los Angeles; David Geffen School of Medicine (P.B.S.), Los Angeles; Department of Pathology and Laboratory Medicine (H.L., S.F.N.), University of California, Los Angeles; Department of Human Genetics (H.L., S.F.N.), David Geffen School of Medicine; Department of Neurology (I.S.), Columbia University, Center for Statistical Genetics, New York; Department of Translational Genomics (D.W.C.), University of Southern California, Los Angeles; Providence Sacred Heart Medical Center and Children's Hospital (S.P.Y.), Spokane, WA; Department of Pathology (S.A.M), University of Iowa, Carver College of Medicine; and Neuromuscular Clinic and Research Center (K.S.), Phoenix, AZ.

Objective: Description of a new variant of the glutamine-fructose-6-phosphate transaminase 1 () gene causing congenital myasthenic syndrome (CMS) in 3 children from 2 unrelated families.

Methods: Muscle biopsies, EMG, and whole-exome sequencing were performed.

Results: All 3 patients presented with congenital hypotonia, muscle weakness, respiratory insufficiency, head lag, areflexia, and gastrointestinal dysfunction. Read More

Genes (Basel) 2020 06 27;11(7). Epub 2020 Jun 27.

John Walton Muscular Dystrophy Research Centre, Translational and Clinical Research Institute, Newcastle University and Newcastle Hospitals NHS Foundation Trust, Newcastle upon Tyne NE1 3BZ, UK.

We identified the known c.1_9del mutation in the gene in four unrelated females from consanguineous families of Turkish origin. All individuals presented with slowly progressive limb-girdle weakness without any dermatological findings, and dystrophic changes observed in their muscle biopsies. Read More

Neurology 2020 04 26;94(16):e1693-e1701. Epub 2020 Mar 26.

From the Department of Neurology (R.H.P.d.M., K.R.K., U.A.B, J.J.V., M.R.T.), Leiden University Medical Center, the Netherlands; and Departments of Ophthalmology (M.A.W., K.P.W.) and Neurology (K.P.W.), University Hospital Zurich, University of Zurich, Switzerland.

Objective: To validate the repetitive ocular vestibular evoked myogenic potentials (RoVEMP) test for diagnostic use in myasthenia gravis (MG) and to investigate its value in diagnostically challenging subgroups.

Methods: The RoVEMP test was performed in 92 patients with MG, 22 healthy controls, 33 patients with a neuromuscular disease other than MG (neuromuscular controls), 4 patients with Lambert-Eaton myasthenic syndrome, and 2 patients with congenital myasthenic syndrome.

Results: Mean decrement was significantly higher in patients with MG (28. Read More

Toxicon 2020 May 14;179:84-91. Epub 2020 Mar 14.

Neurological Unit 1, Fondazione I.R.C.C.S. Istituto Neurologico Carlo Besta, 20133, Milan, Italy. Electronic address:

The Botulinum NeuroToxin (BoNT) comprises several serotypes with distinct properties, mechanisms of action, sensitivity and duration of effect in different species. The serotype A (BoNT/A) is the prevalent neurotoxin applied in human's disease. In this paper we present an overview of the current knowledge regarding the duration of effect and the neuromuscular sprouting of different BoNT serotypes in humans. Read More

Clin Neurophysiol Pract 2020 7;5:46-49. Epub 2020 Feb 7.

Department of Neuroscience, Clinical Neurophysiology, Uppsala University, Uppsala, Sweden.

Introduction: The application of botulinum toxin type A (BoNTA) is accelerating, and this includes the uncontrolled cosmetic use of the BoNTA. Diffusion of BoNTA can disturb neuromuscular transmission in several surrounding and distant muscles and result in clinical manifestations similar to myasthenia gravis (MG).

Case Presentations: We report two cases of patients referred for neurophysiological evaluation of suspected MG. Read More

Eur Arch Otorhinolaryngol 2020 May 18;277(5):1409-1415. Epub 2020 Feb 18.

Division of Phoniatrics-Logopedics, Department of Otorhinolaryngology, Medical University of Vienna, Währinger Gürtel 18-20, 1090, Vienna, Austria.

Purpose: This paper describes a first attempt to quantify LEMG data based on turn number calculation. The results obtained for both healthy and ailing thyroarytenoid (TA) muscles of patients with unilateral vocal fold immobility (UVFI) were compared with the respective qualitative evaluation concerning volitional activity to determine whether the two types of analyses deliver similar results.

Methods: LEMG data obtained from 44 adults with UVFI were considered for the study. Read More

Rinsho Shinkeigaku 2020 Feb 19;60(2):152-156. Epub 2020 Jan 19.

Division of Neurology, Kobe University Graduate School of Medicine.

A 27 year-old Canadian man suffered from fluctuating muscle weakness in the past several years. The patient had a past history of intestinal bleeding, bifid uvula and hypothyroidism in his childhood. Repetitive nerve stimulation tests showed a decrement pattern in the left deltoid muscle. Read More

Neurobiol Aging 2020 02 5;86:182-190. Epub 2019 Nov 5.

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:

Neurodegeneration has increasingly been considered an important factor in the pathogenesis of sarcopenia or age-related loss of muscle mass and strength. Experiments were designed to investigate the fidelity of neuromuscular junction (NMJ) transmission across the lifespan in hindlimb muscles of male and female C57BL/6J mice (at 12, 20, 24, 27, and 29 months of age). Single-fiber electromyography recordings demonstrated abrupt onset of NMJ transmission failure at 27 months of age. Read More