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  • 1.
    Alix, James J. P.
    et al.
    Univ Sheffield, Sheffield Inst Translat Neurosci, 385A Glossop Rd, Sheffield S10 2HQ, S Yorkshire, England.
    Neuwirth, Christoph
    Kantonsspital, Neuromuscular Dis Unit ALS Clin, St Gallen, Switzerland.
    Gelder, Lucy
    Univ Sheffield, Stat Serv Unit, Sheffield, S Yorkshire, England.
    Burkhardt, Christian
    Kantonsspital, Neuromuscular Dis Unit ALS Clin, St Gallen, Switzerland.
    Castro, Jose
    Univ Lisbon, Hosp Santa Maria, Fac Med, Inst Med Mol,Dept Neurosci, Lisbon, Portugal.
    de Carvalho, Mamede
    Univ Lisbon, Hosp Santa Maria, Fac Med, Inst Med Mol,Dept Neurosci, Lisbon, Portugal.
    Gawel, Malgorzata
    Med Univ Warsaw, Dept Neurol, Warsaw, Poland.
    Goedee, Stephan
    UMC Utrecht, Dept Neurol & Neurosurg, Brain Ctr Rudolf Magnus, Utrecht, Netherlands.
    Grosskreutz, Julian
    Jena Univ Hosp, Hans Berger Dept Neurol, Jena, Germany.
    Lenglet, Timothee
    Grp Hosp Pitie Salpetriere, APHP, Dept Neurophysiol, Paris, France.
    Moglia, Cristina
    Univ Torino, ALS Ctr Torino, Dept Neurosci Rita Levi Montalcini, Turin, Italy.
    Omer, Taha
    Biomed Sci Inst TBSI, Trinity Coll, Dublin, Ireland;Beaumont Hosp, Dublin, Ireland.
    Schrooten, Maarten
    Univ Hosp Leuven, Dept Neurol, Leuven, Belgium.
    Nandedkar, Sanjeev
    Natus Med Inc, 15 Dartantra Dr, Hopewell Jct, NY 12533 USA.
    Stålberg, Erik
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Clinical Neurophysiology.
    Barkhaus, Paul E.
    Milwaukee Vet Adm, Med Ctr, Milwaukee, WI USA;Med Coll Wisconsin, Milwaukee, WI 53226 USA.
    Furtula, Jasna
    Aarhus Univ Hosp, Dept Clin Neurophysiol, Aarhus, Denmark.
    van Dijk, Johannes P.
    Univ Ulm, Dept Orthodont, Ulm, Germany.
    Baldinger, Reto
    Kantonsspital, Neuromuscular Dis Unit ALS Clin, St Gallen, Switzerland.
    Costa, Joao
    Univ Lisbon, Hosp Santa Maria, Fac Med, Inst Med Mol,Dept Neurosci, Lisbon, Portugal.
    Otto, Marit
    Aarhus Univ Hosp, Dept Clin Neurophysiol, Aarhus, Denmark.
    Sandberg, Arne
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Clinical Neurophysiology.
    Weber, Markus
    Kantonsspital, Neuromuscular Dis Unit ALS Clin, St Gallen, Switzerland.
    Assessment of the reliability of the motor unit size index (MUSIX) in single subject "round-robin" and multi-centre settings2019In: Clinical Neurophysiology, ISSN 1388-2457, E-ISSN 1872-8952, Vol. 130, no 5, p. 666-674Article in journal (Refereed)
    Abstract [en]

    Objective: The motor unit size index (MUSIX) is incorporated into the motor unit number index (MUNIX). Our objective was to assess the intra-/inter-rater reliability of MUSIX in healthy volunteers across single subject "round robin" and multi-centre settings.

    Methods: Data were obtained from (i) a round-robin assessment in which 12 raters (6 with prior experience and 6 without) assessed six muscles (abductor pollicis brevis, abductor digiti minimi, biceps brachii, tibialis anterior, extensor digitorum brevis and abductor hallucis) and (ii) a multi-centre study with 6 centres studying the same muscles in 66 healthy volunteers. Intrafinter-rater data were provided by 5 centres, 1 centre provided only intra-rater data. Intrafinter-rater variability was assessed using the coefficient of variation (COV), Bland-Altman plots, bias and 95% limits of agreement.

    Results: In the round-robin assessment intra-rater COVs for MUSIX ranged from 7.8% to 28.4%. Inter-rater variability was between 7.8% and 16.2%. Prior experience did not impact on MUSIX values. In the multi-centre study MUSIX was more consistent than the MUNIX. Abductor hallucis was the least reliable muscle.

    Conclusions: The MUSIX is a reliable neurophysiological biomarker of reinnervation.

    Significance: MUSIX could provide insights into the pathophysiology of a range of neuromuscular disorders, providing a quantitative biomarker of reinnervation.

  • 2. Aprile, I
    et al.
    Tonali, P
    Stålberg, Erik
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience.
    Di Stasio, E
    Caliandro, P
    Foschini, M
    Vergili, G
    Padula, L
    Double peak sensory responses: effects of capsaicin2007In: Neurological Sciences, ISSN 1590-1874, E-ISSN 1590-3478, Vol. 28, no 5, p. 264-269Article in journal (Refereed)
    Abstract [en]

    The aim of this study is to verify whether degeneration of skin receptors or intradermal nerve endings by topical application of capsaicin modifies the double peak response obtained by submaximal anodal stimulation. Five healthy volunteers topically applied capsaicin to the finger-tip of digit III (on the distal phalanx) four times daily for 4–5 weeks. Before and after local capsaicin applications, we studied the following electrophysiological findings: compound sensory action potential (CSAP), double peak response, sensory threshold and double peak stimulus intensity. Local capsaicin application causes disappearance or decrease of the second component of the double peak, which gradually increases after the suspension of capsaicin. Conversely, no significant differences were observed for CSAP, sensory threshold and double peak stimulus intensity. This study suggests that the second component of the double peak may be a diagnostic tool suitable to show an impairment of the extreme segments of sensory nerve fibres in distal sensory axonopathy in the early stages of damage, when receptors or skin nerve endings are impaired but undetectable by standard nerve conduction studies.

  • 3. Arimura, K
    et al.
    Arimura, Y
    Ng, A
    Uehara, A
    Nakae, M
    Osame, M
    Stålberg, Erik
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Neuroscience. neurofysiologi.
    The origin of spontaneous discharges in acquired neuromyotonia. A macro EMG study.2005In: Clin Neurophysiol, Vol. 116, p. 1835-1839Article in journal (Refereed)
  • 4. Blijham, PJ
    et al.
    van Dijk, JG
    Stålberg, Erik
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Neuroscience. neurofysiologi.
    Zwarts, MJ
    Recognising F-response interference as a source of increased jitter in stimulated single fibre EMG2006In: Clin Neurophysiol, Vol. 117, p. 388-391Article in journal (Refereed)
  • 5. Caliandro, P.
    et al.
    Evoli, A.
    Stålberg, Erik
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience.
    Granata, G.
    Tonali, P.
    Padua, L.
    The difficulty in confirming clinical diagnosis of myasthenia gravis in a seronegative patient: a possible neurophysiological approach2009In: Neuromuscular Disorders, ISSN 0960-8966, E-ISSN 1873-2364, Vol. 19, no 12, p. 825-827Article in journal (Refereed)
    Abstract [en]

    In seronegative myasthenia gravis repetitive nerve stimulation and single-fibre EMG have a crucial diagnostic value but they may be negative, particularly in repetitive nerve stimulation studies. We report the case of a 43-year-old patient with generalized seronegative myasthenia gravis with negative 3Hz repetitive nerve stimulation at Erb’s point and voluntary single-fibre EMG in the orbicularis oculi. We also performed 6 and 12Hz repetitive nerve stimulation at Erb and stimulated single-fibre EMG in the extensor digitorum communis and our findings were pathological. Our data suggest that, for individual patients with an atypical picture characterised by dissociation between a severe clinical pattern and no definite neurophysiological findings on conventional tests, repetitive nerve stimulation with a stimulation rate higher than 3Hz and/or stimulated single-fibre EMG with an increasing stimulation rate may be helpful.

  • 6. Caliandro, P
    et al.
    Stålberg, Erik
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Clinical Neurophysiology.
    La Torre, G
    Paua, L
    Sensitivity of conventional motor nerve conduction examination in detecting patchy demyelination: a simulated model2007In: Clinical Neurophysiology, ISSN 1388-2457, E-ISSN 1872-8952, Vol. 118, no 7, p. 1577-1585Article in journal (Refereed)
    Abstract [en]

    Objective

    To evaluate, in 5 simulated motor nerves with patchy demyelination: (1) the sensitivity of the conventional motor conduction examination; (2) the conduction velocity of single axons (SA-CV).

    Methods

    Four damaged segments were simulated in each nerve. Myelin impairment was generated by varying two parameters: (1) percent reduction in conduction velocity, i.e. degree of damage (DEGREE); (2) percentage of affected axons, i.e. extent of damage (EXTENT). Myelin impairment was simulated in axons with different diameters. We evaluated: (1) conduction velocity; (2) temporal dispersion of the negative phase of compound motor action potential (CMAP); (3) amplitude decay of CMAP; (4) SA-CV of 20 randomly-chosen axons.

    Results

    When the damage involved both large and small axons, the conduction velocity was pathological only when severe myelin damage involved a large number of axons. Temporal dispersion and amplitude decay were more sensitive than conduction velocity in detecting the damage. In damage involving only large axons or only small axons, all parameters remained in the normal range. SA-CV evaluation was much more sensitive than the conventional studies, regardless of the diameter of the damaged axons.

    Conclusions

    Conventional studies are not sensitive in detecting minimal myelin damage. Decomposing the CMAPs and randomly studying 20 SA-CVs would increase the sensitivity of damage detection.

    Significance

    These results contribute to a better understanding of the relationship between axonal properties and neurophysiological findings in motor nerve demyelination.

  • 7. Caliandro, Pietro
    et al.
    Padua, Luca
    Rossi, Alessandro
    Rossini, Paolo Maria
    Stålberg, Erik
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Clinical Neurophysiology.
    Feurra, Matteo
    Ulivelli, Monica
    Bartalini, Sabina
    Giannini, Fabio
    Rossi, Simone
    Jitter of Corticospinal Neurons During Repetitive Transcranial Magnetic Stimulation: Method and Possible Clinical Implications2014In: Brain Stimulation, ISSN 1935-861X, E-ISSN 1876-4754, Vol. 7, no 4, p. 580-586Article in journal (Refereed)
    Abstract [en]

    Background: Repetitive transcranial magnetic stimulation (rTMS) of the motor cortex activates corticospinal neurons mainly through the depolarization of cortico-cortical axons belonging to interneurons of superficial layers. Objective: We used single-fiber electromyography (SFEMG) to estimate the "central jitter" of activation latency of interneural pools from one pulse of TMS to another. Methods: We evaluated 10 healthy subjects and one patient with multiple sclerosis. By recording SFEMG evoked activity from the left first dorsal interosseous (FDI), we first used a standard repetitive electrical 3 Hz stimulation of the ulnar nerve at the wrist to calculate the mean consecutive difference from at least 10 different potentials. The same procedure was applied during 3 Hz repetitive TMS of the contralateral motor cortex. The corticospinal monosynaptic connection of the FDI and the selectivity of SFEMG recording physiologically justified the subtraction of the "peripheral jitter" from the whole cortico-muscular jitter, obtaining an estimation of the actual "central jitter." Results: All subjects completed the study. The peripheral jitter was 28 mu s +/- 6 and the cortico-muscular jitter was 344 mu s +/- 97. The estimated central jitter was 343 +/- 97 mu s. In the patient the central jitter was 846 mu s, a value more than twice the central jitter in healthy subjects. Conclusion: Current results demonstrate that the evaluation of the central component of the cumulative cortico-muscular latency variability in healthy subjects is feasible with a minimally invasive approach. We present and discuss this methodology and provide a "proof of concept" of its potential clinical applicability in a patient with multiple sclerosis. 

  • 8.
    Chroni, Elisabeth
    et al.
    Univ Patras, Sch Med, Dept Neurol, Patras 26504, Rion, Greece.
    Tendero, Isabel Serrano
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Clinical Neurophysiology. Autonomous Univ Barcelona, Dept Clin Neurophysiol, Vall dHebron Univ Hosp, Barcelona, Spain.
    Punga, Anna Rostedt
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Clinical Neurophysiology.
    Stålberg, Erik
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Clinical Neurophysiology.
    Usefulness of assessing repeater F-waves in routine studies2012In: Muscle and Nerve, ISSN 0148-639X, E-ISSN 1097-4598, Vol. 45, no 4, p. 477-485Article in journal (Refereed)
    Abstract [en]

    INTRODUCTION: Repeater F-waves are sometimes seen in routine studies.

    METHODS: We retrospectively reviewed the clinical significance of repeater F-waves in median, ulnar, and fibular nerve recordings in 50 healthy subjects and groups of 50 patients each with diabetic polyneuropathy, amyotrophic lateral sclerosis, carpal tunnel syndrome, ulnar mononeuropathy, and L5 root lesion. The number of identical F-waves and their repetitions in samples of 20 stimuli were estimated.

    RESULTS: Repeater F-waves occurred significantly more frequently in all nerves and patient groups than in healthy individuals. Their persistence was negatively correlated with that of non-repeater F-waves.

    CONCLUSIONS: Based on the presented material and recording condition it appears that repeater F-waves differentiate between health and disease but not between different types of pathology of motor neurons or their axons. Even in routinely recorded samples of 20 traces, the index of repeater all F-waves could be used as a sign of nerve pathology.

  • 9. Cruccu, G
    et al.
    Stålberg, Erik
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Neuroscience. neurofysiologi.
    Trends in European CN2005In: Clin Neurophysiol, Vol. 116, p. 2507-2509Article in journal (Refereed)
  • 10. Dornonville de la Cour, C
    et al.
    Andersen, H
    Stålberg, Erik
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Neuroscience. Klinisk Neurofysiologi.
    Fuglsang-Frederiksen, A
    Jakobsen, J
    Electrophysiological signs of permanent axonal loss in a follow-up study of Guilla in-Barré syndreome.2005In: Muscle and Nerve, Vol. 31, p. 70-77Article in journal (Refereed)
  • 11. Doroville de la Cour, C
    et al.
    Andersen, H
    Stålberg, Erik
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Neuroscience.
    Fuglsang-Frederiksen, A
    Jakobsen, J
    Electrophysiological signs of permanent axonal loss in a follow-up study of patients with Guillain-Barré syndrome2005In: Muscle Nerve, Vol. 31, p. 70-77Article in journal (Refereed)
  • 12. Ekman, A.
    et al.
    Stålberg, Erik
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience.
    Sundman, E.
    Eriksson, L.I.
    Brudin, L.
    Sandin, R.
    The effect of neuromuscular block and noxious stimulation on hypnosis monitoring during sevoflurane anesthesia2007In: Anesthesia and Analgesia, ISSN 0003-2999, E-ISSN 1526-7598, Vol. 105, no 3, p. 688-695Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: There are conflicting results on the influence of neuromuscular block (NMB) on the bispectral index (BIS). We investigated the influence of two degrees of NMB on BIS, Alaris auditory-evoked potential index (AAI), and the electromyogram (EMG) obtained with needle electrodes from the frontal and temporal muscles, immediately adjacent to the BIS-sensor. METHODS: Twenty patients were anesthetized with sevoflurane, titrated for 30 min to an end-tidal concentration of 1.2% (baseline). Rocuronium was infused to 50% (partial) and 95% (profound) depression of the first twitch in a train-of-four response, the order being randomly chosen. Noxious tetanic electrical stimulation was applied at four occasions: 1) at baseline (control measurement), 2 and 3) at each degree of NMB, and 4) after neostigmine reversal. BIS, AAI, and EMG were obtained 2 min before and 2 min after each noxious stimulation. RESULTS: Median BIS and AAI at baseline were 44 (39-50) and 15 (14-16), respectively. The two degrees of NMB did not affect BIS, AAI, and EMG before noxious stimulation. In contrast, profound NMB altered the BIS and AAI responses to noxious stimulation when compared with partial NMB, (BIS P = 0.01, AAI P < 0.01), after neostigmine reversal (BIS P < 0.01, AAI P = 0.01) and compared with baseline (BIS P = 0.08, AAI P = 0.02). No significant increase in EMG was found. CONCLUSION: BIS and AAI responses to noxious tetanic electrical stimulation are affected by the degree of NMB during sevoflurane anesthesia whereas NMB does not affect BIS or AAI in the absence of noxious stimulation.

  • 13.
    Erik, Stålberg
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Clinical Neurophysiology. Inst Neurosci, Univ Hosp, S-75385 Uppsala, Sverige, Sweden..
    Between genetics and biology. Is ENMG useful in peripheral neuropathy diagnosis and management?2016In: Revue neurologique (Paris), ISSN 0035-3787, E-ISSN 2213-0004, Vol. 172, no 10, p. 627-631Article in journal (Refereed)
    Abstract [en]

    Neurography and EMG are complementary techniques used in the diagnosis and monitoring of neuropathies. Both assess function of the peripheral nervous system and provide clinically useful information regarding the functional status of peripheral nerves. This information is not readily obtainable using biochemical, genetic or imaging techniques. I will discuss the role of these techniques in the diagnosis and management of neuropathies and some limitations of these techniques. These methods are routinely used in an EMG lab. These are most useful when used in conjunction with clinical examination to answer a well-defined clinical question. Reference values are required for interpretation of the data.

  • 14. Farbru, E
    et al.
    Gilhus, NE
    Barnes, MP
    Borg, K
    de Visser, M
    Driessen, A
    Howard, R
    Nollet, F
    Opara, J
    Stålberg, Erik
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Clinical Neurophysiology.
    EFNS guideline on diagnosis and management of post-polio syndrome. Report of an EFNS task force2006In: European Journal of Neurology, ISSN 1351-5101, E-ISSN 1468-1331, Vol. 13, no 8, p. 795-801Article in journal (Refereed)
    Abstract [en]

    Post-polio syndrome (PPS) is characterized by new or increased muscular weakness, atrophy, muscle pain and fatigue several years after acute polio. The aim of the article is to prepare diagnostic criteria for PPS, and to evaluate the existing evidence for therapeutic interventions. The Medline, EMBASE and ISI databases were searched. Consensus in the group was reached after discussion by e-mail. We recommend Halstead's definition of PPS from 1991 as diagnostic criteria. Supervised, aerobic muscular training, both isokinetic and isometric, is a safe and effective way to prevent further decline for patients with moderate weakness (Level B). Muscular training can also improve muscular fatigue, muscle weakness and pain. Training in a warm climate and non-swimming water exercises are particularly useful (Level B). Respiratory muscle training can improve pulmonary function. Recognition of respiratory impairment and early introduction of non-invasive ventilatory aids prevent or delay further respiratory decline and the need for invasive respiratory aid (Level C). Group training, regular follow-up and patient education are useful for the patients’ mental status and well-being. Weight loss, adjustment and introduction of properly fitted assistive devices should be considered (good practice points). A small number of controlled studies of potential-specific treatments for PPS have been completed, but no definitive therapeutic effect has been reported for the agents evaluated (pyridostigmine, corticosteroids, amantadine). Future randomized trials should particularly address the treatment of pain, which is commonly reported by PPS patients. There is also a need for studies evaluating the long-term effects of muscular training.

  • 15.
    Feresiadou, Amalia
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Neurology.
    Casar Borota, Olivera
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Clinical and experimental pathology.
    Dragomir, Anca
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Clinical and experimental pathology.
    Oldfors, Carola Hedberg
    Univ Gothenburg, Inst Biomed, Dept Pathol & Genet, Gothenburg, Sweden..
    Stålberg, Erik
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Clinical Neurophysiology.
    Oldfors, Anders
    Univ Gothenburg, Inst Biomed, Dept Pathol & Genet, Gothenburg, Sweden..
    Tubular aggregates in congenital myasthenic syndrome2018In: Neuromuscular Disorders, ISSN 0960-8966, E-ISSN 1873-2364, Vol. 28, no 2, p. 174-175Article in journal (Other academic)
  • 16. Hammarberg, B
    et al.
    Stålberg, Erik
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Neuroscience. Klinisk Neurofysiologi.
    Novel ideas for fast muscle action potential simulations using the line source model2002In: IEEE, Vol. 51, p. 1888-1897Article in journal (Refereed)
  • 17. Hokkoku, Keiichi
    et al.
    Sonoo, Masahiro
    Higashihara, Mana
    Stålberg, Erik
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Clinical Neurophysiology.
    Shimizu, Teruo
    Electromyographs of the flexor digitorum profundus muscle are useful for the diagnosis of inclusion body myositis2012In: Muscle and Nerve, ISSN 0148-639X, E-ISSN 1097-4598, Vol. 46, no 2, p. 181-186Article in journal (Refereed)
    Abstract [en]

    Introduction: The frequent observation of high-amplitude and long-duration motor unit potentials (MUPs) in inclusion body myositis (IBM) is problematic, because it may lead to a misdiagnosis of amyotrophic lateral sclerosis (ALS).

    Objective: To document the diagnostic utility of EMG from the flexor digitorum profundus (FDP) muscle for IBM. M

    ethods: Quantitative analyses of MUP parameters were performed in the FDP and biceps brachii (BB) muscles from 7 biopsy-confirmed IBM patients.

    Results: In the FDP muscle, all MUP parameters were significantly decreased in IBM patients, which indicated the predominance of low-amplitude and short-duration MUPs in this muscle. In the BB muscle, most parameters were increased, suggesting the frequent contamination of high-amplitude and long-duration MUPs.

    Conclusions: Low-amplitude MUPs in the FDP muscle indicate the presence of an advanced myopathy in this muscle that was extremely weak for all subjects. Examining the FDP muscle would reduce the chance of misdiagnosing IBM as ALS.

  • 18. Kouyoumdjian, Joao A.
    et al.
    Stålberg, Erik V.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Clinical Neurophysiology.
    Concentric needle jitter in stimulated frontalis in 20 healthy subjects2012In: Muscle and Nerve, ISSN 0148-639X, E-ISSN 1097-4598, Vol. 45, no 2, p. 276-278Article in journal (Refereed)
    Abstract [en]

    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 16.05 +/- 2.73 mu s and 16.05 +/- 5.96 mu s, respectively. The suggested limit for mean MCD is 22 mu s and for outliers is 28 mu s.

  • 19. Kouyoumdjian, Joao A.
    et al.
    Stålberg, Erik V.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Clinical Neurophysiology.
    Concentric needle jitter on voluntary activated frontalis in 20 healthy subjects2013In: Muscle and Nerve, ISSN 0148-639X, E-ISSN 1097-4598, Vol. 47, no 3, p. 440-442Article in journal (Refereed)
    Abstract [en]

    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 19.9 +/- 2.9 s, 19.9 +/- 6.6 s, and 26.9 +/- 4.4 s, respectively. Conclusion: The suggested upper normal limit for mean MCD is 26 s and for outliers is 36 s.

  • 20. Kouyoumdjian, Joao Aris
    et al.
    da Silva Fanani, Adriana Cristina
    Stålberg, Erik V.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Clinical Neurophysiology.
    Concentric needle jitter on stimulated frontalis and extensor digitorum in 20 myasthenia gravis patients2011In: Muscle and Nerve, ISSN 0148-639X, E-ISSN 1097-4598, Vol. 44, no 6, p. 912-918Article in journal (Refereed)
    Abstract [en]

    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. Percutaneous (FR) and intramuscular needle (ED) stimulation approaches were used. Jitter was expressed as the mean consecutive difference (MCD). The filter settings were from 1000 HZ to 10 kHZ. Results: Abnormal MCD was found in 85% for both ED and FR and in 90% when combining the two muscles. An abnormal percentage of outliers was found in 90% for ED and 85% for FR. The mean MCD did not show a difference for ED and FR, but the percentage of outliers and blocking were higher in FR. Abnormality was found in 93.7% (generalized) and in 75% (ocular) of MG cases. For ED outliers abnormality was greater than the MCD. Conclusion: CNE jitter is reliable for investigation of MG, although borderline findings should be judged with caution.

  • 21. Kouyoumdjian, Joao Aris
    et al.
    Stålberg, Erik
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Clinical Neurophysiology.
    Stimulated jitter with concentric needle in 42 myasthenia gravis patients2013In: Arquivos de Neuro-Psiquiatria, ISSN 0004-282X, E-ISSN 1678-4227, Vol. 71, no 4, p. 237-243Article in journal (Refereed)
    Abstract [en]

    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 +/- 17.2 years-old) were studied. Jitter was expressed as the mean consecutive difference (MCD). Results: MCD in extensor digitorum was 61.6 mu s (abnormal in 85.7%) and in frontalis 57.3 mu s (abnormal in 88.1%). Outliers represented 90.5% for extensor digitorum and 88.1% for frontalis. At least one jitter parameter was abnormal in 90.5% of the combined studies. Acetylcholine receptor antibody was abnormal in 85.7% of the cases. Conclusions: Stimulated jitter recordings measured from muscles using concentric needle electrode can be used for myasthenia gravis diagnosis with high sensitivity. Extensive normative studies are still lacking and, therefore, borderline findings should be judged with great caution.

  • 22.
    Kouyoumdjian, João Aris
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience.
    Stålberg, Erik
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience.
    Concentric needle single fiber electromyography: Normative jitter values on voluntary activated Extensor Digitorum Communis2007In: Arquivos de Neuro-Psiquiatria, ISSN 0004-282X, E-ISSN 1678-4227, Vol. 65, no 2B, p. 446-449Article in journal (Refereed)
    Abstract [en]

    Single fiber electromyography (SFEMG) is the most sensitive clinical neurophysiological test for neuromuscular junction disorders, particularly myasthenia gravis. Normal values for jitter obtained with SFEMG electrode have been published, but there are few publications for concentric needle electrode (CNE). The aim of this study was to discuss the possibilities to analyse the jitter in CNE recordings and to get normal values of jitter for voluntary activated Extensor Digitorum Communis using disposable CNE. Fifty normal subjects were studied, 16 male and 34 female with a mean age of 37.1±10.3 years (19-55). The jitter values of action potentials pairs of isolated muscular fibers were expressed as the mean consecutive difference (MCD) after 20 analysed potential pairs. The mean MCD (n=50) obtained was 24.2±2.8 µs (range of mean values in each subject was 18-31). Upper 95% confidence limit is 29.8 µs. The mean jitter of all potential pairs (n=1000) obtained was 24.07±7.30 µs (range 9-57). A practical upper limit for individual data is set to 46 µs. The mean interpotential interval (MIPI) was 779±177 µs (range of individual mean values was 530-1412); there were no potentials with impulse blocking. The present study confirms that CNE is suitable for jitter analysis although certain precautions must be mentioned. Our findings of jitter values with CNE were similar to some other few reports in literature.

  • 23. Loseth, S.
    et al.
    Bagenholm, A.
    Torbergsen, T.
    Stalberg, Erik
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Clinical Neurophysiology.
    Peripheral neuropathy caused by severe hypothermia2013In: Clinical Neurophysiology, ISSN 1388-2457, E-ISSN 1872-8952, Vol. 124, no 5, p. 1019-1024Article in journal (Refereed)
    Abstract [en]

    Objective: To report follow-up data in the evaluation of peripheral neuropathy in a 29-year old female after accidental deep hypothermia (13.7 degrees C) in 1999. Methods: Nerve conduction studies (NCS) and electromyography (EMG) were performed 20 days after the accident and again after 5 months and 1, 3, 5 and 11 years. Macro EMG was performed after 3, 5 and 11 years. To evaluate small fiber function, RR-interval, sympathetic skin response, quantitative sensory testing and skin biopsy for quantification of intra-epidermal nerve fiber density were performed in 2009. Results: In the intensive care unit sensory and motor responses were absent except for the tibial nerves, and EMG showed profuse denervation. Improvement of amplitudes and conduction velocities was seen during the first 5 years. Muscular atrophy of hand muscles persisted. Large fibers were involved more extensively than small fibers. Conclusions: A severe axonal sensorimotor polyneuropathy developed in the intensive care unit following severe hypothermia. The mechanism was most likely cold injury to peripheral nerves. Significance: The clinical picture and the laboratory findings indicate that even multi-organ dysfunction and, of specific interest in this study, a severe axonal degeneration may come to a good restitution after long time.

  • 24. Löseth, S
    et al.
    Lindal, S
    Stålberg, Erik
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Neuroscience. neurofysiologi.
    Mellgren, SI
    Intraepidermal nerve fibre density, quantitative sensory testing and nerve conduction studies in a patient material with symptoms and signs of sensory polyneuropathy2006In: Eur J Neurol, Vol. 13, p. 105-111Article in journal (Refereed)
  • 25.
    Løseth, Sissel
    et al.
    Univ Hosp North Norway, Dept Neurol & Neurophysiol, N-9038 Tromso, Norway.;Arctic Univ Norway, Dept Clin Med, Tromso, Norway..
    Stålberg, Erik V.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Clinical Neurophysiology.
    Lindal, Sigurd
    Univ Hosp North Norway, Dept Clin Pathol, N-9038 Tromso, Norway.;Arctic Univ Norway, Dept Med Biol, Tromso, Norway..
    Olsen, Edel
    Arctic Univ Norway, Dept Clin Med, Tromso, Norway..
    Jorde, Rolf
    Arctic Univ Norway, Dept Clin Med, Tromso, Norway.;Univ Hosp North Norway, Dept Internal Med, N-9038 Tromso, Norway..
    Mellgren, Svein I.
    Univ Hosp North Norway, Dept Neurol & Neurophysiol, N-9038 Tromso, Norway.;Arctic Univ Norway, Dept Clin Med, Tromso, Norway..
    Small and large fiber neuropathy in those with type 1 and type 2 diabetes: a 5-year follow-up study2016In: Journal of the peripheral nervous system, ISSN 1085-9489, E-ISSN 1529-8027, Vol. 21, no 1, p. 15-21Article in journal (Refereed)
    Abstract [en]

    The purpose of this study was to evaluate progression of diabetic polyneuropathy and differences in the spectrum and evolution of large- and small-fiber involvement in patients with diabetes type 1 and 2 over 5 years. Fifty-nine patients (35 type 1 and 24 type 2) were included. Nerve conduction studies (NCS), quantitative sensory testing, skin biopsy for quantification of intraepidermal nerve fiber density (IENFD), symptom scoring and clinical evaluations were performed. Z-scores were calculated to adjust for the physiologic effects of age and height/gender. Neuropathic symptoms were not significantly more frequent in type 2 than in type 1 diabetic patients at follow-up (54% vs. 37%). The overall mean NCS Z-score remained within the normal range, but there was a small significant decline after 5 years in both groups: type 1 (p = 0.004) and type 2 (p = 0.02). Mean IENFD Z-scores changed from normal to abnormal in both groups, but only significantly in those with type 2 diabetes (reduction from 7.9 +/- 4.8 to 4.3 +/- 2.8 fibers/mm, p = 0.006). Cold perception threshold became more abnormal only in those with type 2 diabetes (p = 0.049). There was a minimal progression of large fiber neuropathy in both groups. Reduction of small fibers predominated and progressed more rapidly in those with type 2 diabetes.

  • 26.
    Marrero, Humberto Gonzalez
    et al.
    Karolinska Inst, Dept Clin Neurosci, Clin Neurophysiol Sect, Stockholm, Sweden.
    Stålberg, Erik V
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Clinical Neurophysiology.
    Optimizing testing methods and collection of reference data for differentiating critical illness polyneuropathy from critical illness myopathy.2016In: Muscle and Nerve, ISSN 0148-639X, E-ISSN 1097-4598, Vol. 53, no 4, p. 555-563Article in journal (Refereed)
    Abstract [en]

    INTRODUCTION: In severe acute quadriplegic myopathy in intensive care unit (ICU) patients, muscle fibers are electrically inexcitable; in critical illness polyneuropathy the excitability remains normal. Conventional electrodiagnostic methods do not provide the means to adequately differentiate between them.

    OBJECTIVE: To further optimize methodology for the study of critically ill ICU patients and to create a reference database in healthy controls.

    METHODS: Different electrophysiologic protocols were tested to find sufficiently robust and reproducible techniques for clinical diagnostic applications.

    RESULTS: Many parameters show large test-retest variability within the same healthy subject. Reference values have been collected and described as a basis for studies of weakness in critical illness.

    DISCUSSION: Using the ratio of neCMAP/dmCMAP (response from nerve and direct muscle stimulation), refractory period, and stimulus-response curves may optimize the electrodiagnostic differentiation of patients with critical illness myopathy from those with critical illness polyneuropathy.

  • 27.
    Melberg, A
    et al.
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Neuroscience.
    Oldfors, A
    Blomström-Lundqvist, C
    Department of Medical Sciences.
    Stålberg, E
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Neuroscience.
    Carlsson, B
    Larsson, E
    Department of Genetics and Pathology.
    Lidell, C
    Eeg-Olofsson, K E
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Neuroscience.
    Wikström, G
    Henriksson, G
    Dahl, N
    Department of Genetics and Pathology.
    Autosomal dominant myofibrillar myopathy with arrhythmogenic right ventricular cardiomyopathy linked to chromosome 10q.1999In: Ann Neurol, ISSN 0364-5134, Vol. 46, no 5, p. 684-92Article in journal (Refereed)
  • 28.
    Nandedkar, Sanjeev D.
    et al.
    Natus Med Inc, Hopewell Jct, NY USA.
    Barkhaus, Paul E.
    Med Coll Wisconsin, Milwaukee, WI 53226 USA.
    Stålberg, Erik
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Clinical Neurophysiology. Univ Hosp, Uppsala, Sweden.
    Neuwirth, Christoph
    Kantonsspital St Gallen, St Gallen, Switzerland.
    Weber, Markus
    Kantonsspital St Gallen, St Gallen, Switzerland.
    Motor unit number index: Guidelines for recording signals and their analysis2018In: Muscle and Nerve, ISSN 0148-639X, E-ISSN 1097-4598, Vol. 58, no 3, p. 374-380Article in journal (Refereed)
    Abstract [en]

    Introduction: This study proposes guidelines for motor unit number index (MUNIX) recording and analysis. Methods: MUNIX was measured in control participants and in patients with amyotrophic lateral sclerosis. Changes in MUNIX values due to E1 electrode position, number of surface electromyography interference pattern (SIP) epochs, SIP epoch duration, force of contraction, and outlier data points were investigated. Results: MUNIX depends on optimized compound muscle action potential (CMAP) amplitude. Individual muscles showed variations when the number of epochs was low or when the SIP duration was short. Longer SIP duration allowed better recognition of artifacts. MUNIX results were affected by SIP values at all force levels but was more affected when SIP area was low. Discussion: We recommend changing the E1 electrode position to maximize CMAP amplitude. Twenty or more SIP signals of 500-ms duration should be recorded by using force levels ranging from slight to maximum. Traces should be reviewed to identify and exclude signals with tremor or solitary spikes.

  • 29. Nandedkar, Sanjeev D.
    et al.
    Barkhaus, Paul E.
    Stålberg, Erik V.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Clinical Neurophysiology.
    Cumulative Motor Index: An Index to Study Progression of Amyotrophic Lateral Sclerosis2015In: Journal of clinical neurophysiology, ISSN 0736-0258, E-ISSN 1537-1603, Vol. 32, no 1, p. 79-85Article in journal (Refereed)
    Abstract [en]

    Purpose:To study disease progression in patients with amyotrophic lateral sclerosis (ALS), we have developed the cumulative motor index (CMI) using the compound muscle action potential amplitude recorded in multiple upper and lower limb muscles.Methods:To study its reproducibility, CMI was measured by 2 operators in 10 healthy subjects on 2 occasions. In 15 patients with ALS, CMI and ALS functional rating score (revised) were measured at 3- to 6-month interval for 12 months or longer.Results:The CMI had good reproducibility in healthy subjects. In one patient with ALS, CMI and ALS functional rating score (revised) remained relatively unchanged. In all remaining 14 patients with disease progression, CMI decreased in a relatively monotonic manner. At 1 year after baseline study, CMI was reduced more than ALS functional rating score (revised) in 10 patients. CMI measurements were possible for longer time period, than analysis from a single distal muscle recording.Conclusions:The CMI can be measured using standard equipment and software available in most electrodiagnostic laboratories. This may be a simple measurement that can be used for clinical studies of ALS progression over longer time periods.

  • 30. Nandedkar, Sanjeev D.
    et al.
    Barkhaus, Paul E.
    Stålberg, Erik V.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Clinical Neurophysiology.
    Reproducibility of munix in patients with amyotrophic lateral sclerosis2011In: Muscle and Nerve, ISSN 0148-639X, E-ISSN 1097-4598, Vol. 44, no 6, p. 919-922Article in journal (Refereed)
    Abstract [en]

    Introduction: In this study we investigated the reproducibility of motor unit number index (MUNIX) in patients with amyotrophic lateral sclerosis (ALS). Methods: MUNIX was recorded in patients with ALS. Studies were performed in 18 thenar and 18 hypothenar muscles by two operators. The reproducibility was assessed using mean MUNIX values, linear regression, correlation coefficient, and coefficient of variation (COV) in individual studies. Results: The mean values showed no significant difference. The linear regression showed a strong correlation. Most patients had low COV. A high COV was seen when MUNIX was very low. The COV was higher in thenar than in hypothenar muscles. Conclusions: MUNIX has very good reproducibility in ALS patients. COV may exaggerate interoperator variation when MUNIX is very low. The higher variability in the thenar muscle is also due to variability in compound muscle action potential amplitude. Although both muscles show good reproducibility, the hypothenar is better suited for serial studies in individual patients.

  • 31.
    Nandedkar, Sanjeev D.
    et al.
    Natus Medical Inc, New York.
    Sanders, Donald B.
    Duke University, Medical Center, Department of Neurology.
    Hobson-Webb, Lisa D.
    Duke University, Medical Center, Department of Neurology.
    Billakota, Santoshi
    Duke University, Medical Center, Department of Neurology.
    Barkhaus, Paul E.
    Medical College of Wisconsin, Department of Neurology.
    Stålberg, Erik
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Clinical Neurophysiology.
    THE EXTRAPOLATED REFERENCE VALUES PROCEDURE: THEORY, ALGORITHM, AND RESULTS IN PATIENTS AND CONTROL SUBJECTS2018In: Muscle and Nerve, ISSN 0148-639X, E-ISSN 1097-4598, Vol. 57, no 1, p. 90-95Article in journal (Refereed)
    Abstract [en]

    Introduction: Reference values (RVs) are required to separate normal from abnormal values obtained in electrodiagnostic (EDx) testing. However, it is frequently impractical to perform studies on control subjects to obtain RVs. The Extrapolated Reference Values (E-Ref) procedure extracts RVs from data obtained during clinically indicated EDx testing. We compared the E-Ref results with established RVs in several sets of EDx data.

    Methods: The mathematical basis for E-Ref was explored to develop an algorithm for the E-Ref procedure. To test the validity of this algorithm, it was applied to simulated and real jitter measurements from control subjects and patients with myasthenia gravis, and to nerve conduction studies from patients with various conditions referred for EDx studies.

    Results: There was good concordance between E-Ref and RVs for all evaluated data sets.

    Discussion: E-Ref is a promising method to develop RVs.

  • 32.
    Nandedkar, Sanjeev D.
    et al.
    Natus Med Inc, Hopewell Jct, NY USA.
    Sanders, Donald B.
    Duke Univ, Med Ctr, Durham, NC USA.
    Hobson-Webb, Lisa D.
    Duke Univ, Med Ctr, Durham, NC USA.
    Billlakota, Santoshi
    Duke Univ, Med Ctr, Durham, NC USA.
    Barkhaus, Paul E.
    Med Coll Wisconsin, Milwaukee, WI 53226 USA.
    Stålberg, Erik
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Clinical Neurophysiology.
    Estimation of Reference Intervals for Transcranial Magnetic Stimulation: Derived Parameters Via the Hoffman Indirect Method Reply2018In: Muscle and Nerve, ISSN 0148-639X, E-ISSN 1097-4598, Vol. 58, no 4, p. E31-E32Article in journal (Other academic)
  • 33. Nandedkar, SD
    et al.
    Nandedkar, K
    Barkhaus, PE
    Stålberg, Erik
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Neuroscience. Klinisk neurofysiologi.
    Motor Unit Number Index (MUNIX)2004In: IEEE Trans Biomed Eng, Vol. 51, p. 2209-2211Article in journal (Refereed)
  • 34. Nandedkar, SD
    et al.
    Stålberg, Erik
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Neuroscience. Klinisk Neurofysiologi.
    Sanders, DB
    Quantitative EMG2001In: Electrodiagnostic medicine, 2001, p. 293-356Chapter in book (Refereed)
  • 35. Navallas, Javier
    et al.
    Rodriguez, Javier
    Stålberg, Erik
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Clinical Neurophysiology.
    Scanning electromyography2012In: EMG Methods for evaluating Muscle and Nerve function / [ed] Schwartz M, InTech , 2012, p. 471-490Chapter in book (Refereed)
    Abstract [en]

    The study of the anatomy and physiology of the motor unit has important implications in the diagnosis and follow-up of neuromuscular pathologies. Muscle action potentials allow the use of electrophysiological techniques based on electromyography (EMG) to make inferences about muscle structure, state and behaviour. Scanning EMG is one such technique that can record the temporal and spatial distribution of electrical activity of a single motor unit, allowing for deep insight into the structure and function of motor units. In this chapter, we describe the scanning EMG technique in detail, both from a technical and clinical point of view. A brief review of the motor unit anatomy and physiology is provided in Section 2. The technique, the apparatus setup, the recording procedure and the signal processing required are described in Section 3. Key results of studies using scanning EMG are reviewed in Section 4, including findings related to motor unit organisation in normal muscle and how changes due to pathology are reflected using this electrophysiological technique. Finally, Section 5 provides some hints regarding the use of scanning EMG in research.

  • 36.
    Neuwirth, Christoph
    et al.
    Kantonsspital St Gallen, ALS Clin, Neuromuscular Dis Unit, Rorschacherstr 95, CH-9007 St Gallen, Switzerland..
    Barkhaus, Paul E.
    Med Coll Wisconsin, Milwaukee, WI 53226 USA..
    Burkhardt, Christian
    Kantonsspital St Gallen, ALS Clin, Neuromuscular Dis Unit, Rorschacherstr 95, CH-9007 St Gallen, Switzerland..
    Castro, Jose
    Univ Lisbon, Hosp Santa Maria, Fac Med, Inst Mol Med,Dept Neurosci, P-1699 Lisbon, Portugal..
    Czell, David
    Kantonsspital Winterthur, Winterthur, Switzerland..
    de Carvalho, Mamede
    Univ Lisbon, Hosp Santa Maria, Fac Med, Inst Mol Med,Dept Neurosci, P-1699 Lisbon, Portugal.;Natus Med Inc, Middleton, WI USA..
    Nandedkar, Sanjeev
    Stålberg, Erik
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Clinical Neurophysiology.
    Weber, Markus
    Kantonsspital St Gallen, ALS Clin, Neuromuscular Dis Unit, Rorschacherstr 95, CH-9007 St Gallen, Switzerland.;Univ Basel Hosp, Dept Neurol, CH-4031 Basel, Switzerland..
    Motor Unit Number Index (MUNIX) detects motor neuron loss in pre-symptomatic muscles in Amyotrophic Lateral Sclerosis2017In: Clinical Neurophysiology, ISSN 1388-2457, E-ISSN 1872-8952, Vol. 128, no 3, p. 495-500Article in journal (Refereed)
    Abstract [en]

    Objective: Motor Unit Number Index (MUNIX) is a quantitative neurophysiological measure that provides an index of the number of lower motor neurons supplying a muscle. It reflects the loss of motor neurons in patients with Amyotrophic Lateral Sclerosis (ALS). However, it is unclear whether MUNIX also detects motor unit loss in strong, non-wasted muscles. Methods: Three centres measured MUNIX in 49 ALS patients every three months in six different muscles (abductor pollicis brevis, abductor digiti minimi, biceps brachii, tibialis anterior, extensor digitorum brevis, abductor hallucis) on the less affected side. The decline of MUNIX in initially non-wasted, clinically strong muscles (manual muscle testing, MMT grade 5) was analysed before and after onset of weakness. Results: In 49 subjects, 151 clinically strong muscles developed weakness and were included for analysis. The average monthly relative loss of MUNIX was 5.0% before and 5.6% after onset of weakness. This rate of change was significantly higher compared to ALS functional rating scale (ALSFRS-R) and compound muscle action potential (CMAP) change over 12 months prior to the onset of muscle weakness (p = 0.024). Conclusion: MUNIX is an electrophysiological marker that detects lower motor neuron loss in ALS, before clinical weakness becomes apparent by manual muscle testing. Significance: This makes MUNIX a good biomarker candidate for disease progression and possibly pharmacodynamics responds.

  • 37.
    Neuwirth, Christoph
    et al.
    Kantonsspital St Gallen, ALS Clin, Neuromuscular Dis Unit, CH-9007 St Gallen, Switzerland..
    Barkhaus, Paul E.
    Med Coll Wisconsin, Milwaukee, WI 53226 USA..
    Burkhardt, Christian
    Kantonsspital St Gallen, ALS Clin, Neuromuscular Dis Unit, CH-9007 St Gallen, Switzerland..
    Castro, Jose
    Univ Lisbon, Fac Med, Hosp Santa Maria, Dept Neurosci,Inst Med Mol, P-1699 Lisbon, Portugal..
    Czell, David
    Kantonsspital Winterthur, Winterthur, Switzerland..
    de Carvalho, Mamede
    Univ Lisbon, Fac Med, Hosp Santa Maria, Dept Neurosci,Inst Med Mol, P-1699 Lisbon, Portugal..
    Nandedkar, Sanjeev
    Natus Med Inc, Middleton, WI USA..
    Stålberg, Erik
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Clinical Neurophysiology.
    Weber, Markus
    Kantonsspital St Gallen, ALS Clin, Neuromuscular Dis Unit, CH-9007 St Gallen, Switzerland.;Univ Basel Hosp, Dept Neurol, CH-4031 Basel, Switzerland..
    Tracking motor neuron loss in a set of six muscles in amyotrophic lateral sclerosis using the Motor Unit Number Index (MUNIX): a 15-month longitudinal multicentre trial2015In: Journal of Neurology, Neurosurgery and Psychiatry, ISSN 0022-3050, E-ISSN 1468-330X, Vol. 86, no 11, p. 1172-1179Article in journal (Refereed)
    Abstract [en]

    Background Motor Unit Number Index (MUNIX) is a novel neurophysiological measure that provides an index of the number of functional lower motor neurons in a given muscle. So far its performance across centres in patients with amyotrophic lateral sclerosis (ALS) has not been investigated. Objective To perform longitudinal MUNIX recordings in a set of muscles in a multicentre setting in order to evaluate its value as a marker of disease progression. Methods Three centres applied MUNIX in 51 ALS patients over 15 months. Six different muscles (abductor pollicis brevis, abductor digiti minimi, biceps brachii, tibialis anterior, extensor dig. brevis, abductor hallucis) were measured every 3 months on the less affected side. The decline between MUNIX and ALSFRS-R was compared. Results 31 participants reached month 12. For all participants, ALSFRS-R declined at a rate of 2.3%/month. Using the total score of all muscles, MUNIX declined significantly faster by 3.2%/month (p <= 0.02). MUNIX in individual muscles declined between 2.4% and 4.2%, which differed from ASLFRS-R decline starting from month 3 (p <= 0.05 to 0.002). Subgroups with bulbar, lower and upper limb onset showed different decline rates of ALSFRS-R between 1.9% and 2.8%/month, while MUNIX total scores showed similar decline rates over all subgroups. Mean intraclass correlation coefficient for MUNIX intra-rater reliability was 0.89 and for inter-rater reliability 0.80. Conclusion MUNIX is a reliable electrophysiological biomarker to track lower motor neuron loss in ALS.

  • 38. Nicole, Sophie
    et al.
    Chaouch, Amina
    Torbergsen, Torberg
    Bauche, Stephanie
    de Bruyckere, Elodie
    Fontenille, Marie-Josephine
    Horn, Morten A.
    van Ghelue, Marijke
    Loseth, Sissel
    Issop, Yasmin
    Cox, Daniel
    Mueller, Juliane S.
    Evangelista, Teresinha
    Stålberg, Erik
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Clinical Neurophysiology.
    Ioos, Christine
    Barois, Annie
    Brochier, Guy
    Sternberg, Damien
    Fournier, Emmanuel
    Hantai, Daniel
    Abicht, Angela
    Dusl, Marina
    Laval, Steven H.
    Griffin, Helen
    Eymard, Bruno
    Lochmueller, Hanns
    Agrin mutations lead to a congenital myasthenic syndrome with distal muscle weakness and atrophy2014In: Brain, ISSN 0006-8950, E-ISSN 1460-2156, Vol. 137, no P9, p. 2429-2443Article in journal (Refereed)
    Abstract [en]

    Congenital myasthenic syndromes are a clinically and genetically heterogeneous group of rare diseases resulting from impaired neuromuscular transmission. Their clinical hallmark is fatigable muscle weakness associated with a decremental muscle response to repetitive nerve stimulation and frequently related to postsynaptic defects. Distal myopathies form another clinically and genetically heterogeneous group of primary muscle disorders where weakness and atrophy are restricted to distal muscles, at least initially. In both congenital myasthenic syndromes and distal myopathies, a significant number of patients remain genetically undiagnosed. Here, we report five patients from three unrelated families with a strikingly homogenous clinical entity combining congenital myasthenia with distal muscle weakness and atrophy reminiscent of a distal myopathy. MRI and neurophysiological studies were compatible with mild myopathy restricted to distal limb muscles, but decrement (up to 72%) in response to 3Hz repetitive nerve stimulation pointed towards a neuromuscular transmission defect. Post-exercise increment (up to 285%) was observed in the distal limb muscles in all cases suggesting presynaptic congenital myasthenic syndrome. Immunofluorescence and ultrastructural analyses of muscle end-plate regions showed synaptic remodelling with denervation-reinnervation events. We performed whole-exome sequencing in two kinships and Sanger sequencing in one isolated case and identified five new recessive mutations in the gene encoding agrin. This synaptic proteoglycan with critical function at the neuromuscular junction was previously found mutated in more typical forms of congenital myasthenic syndrome. In our patients, we found two missense mutations residing in the N-terminal agrin domain, which reduced acetylcholine receptors clustering activity of agrin in vitro. Our findings expand the spectrum of congenital myasthenic syndromes due to agrin mutations and show an unexpected correlation between the mutated gene and the associated phenotype. This provides a good rationale for examining patients with apparent distal myopathy for a neuromuscular transmission disorder and agrin mutations.

  • 39. Padula, Luca
    et al.
    Caliandro, Pietro
    Stålberg, Erik
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience.
    A novel approach to the measurement of motor conduction velocity using a single fibre EMG electrode2007In: Clinical Neurophysiology, ISSN 1388-2457, E-ISSN 1872-8952, Vol. 118, no 9, p. 1985-1990Article in journal (Refereed)
    Abstract [en]

    OBJECTIVE: To evaluate whether, for patients with suspected myelin impairment, the sensitivity of motor nerve conduction studies can be increased by using an SFEMG electrode which makes it possible to study conduction velocity in a small number of axons (SF-CV). METHODS: We studied 22 consecutive patients with suspected neuropathy through conventional motor conduction study and through SF-CV. For each patient we selected a nerve that was normal at conventional neurography and studied it through SF-CV. Also, we performed SF-CV in 15 healthy subjects. We considered 36 m/s as the low limit of normal SF-CV (the normal value commonly accepted in the literature for the slowest alpha motor axons). RESULTS: In the healthy subjects we never observed abnormal SF-CV values. Of the 22 patients, in 18 the conventional tests showed abnormal findings suggestive of neuropathy. The remaining 4 patients were completely normal at the conventional tests. Through SF-CV we studied 22 nerves that were normal at the conventional tests. Fourteen of 22 (64%) nerves presented pathological SF-CV test. Half of the patients with normal findings at the conventional tests showed pathological SF-CV test. CONCLUSIONS: SF-CV evaluation may be useful in detecting early, mild, or partial myelin damage, because it makes it possible to detect nerve conduction slowing when conventional tests are normal. SIGNIFICANCE: Increasing sensitivity of motor conduction evaluation.

  • 40.
    Rostedt, Anna
    et al.
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Neuroscience. neurofysiologi.
    Padua, L
    Stålberg, Erik
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Neuroscience. neurofysiologi.
    Correlation between a patient-derived functional questionnaire and abnormal neuromuscular transmission in myasthenia gravis patients2005In: Clin Neurophysiol, Vol. 116, p. 2058-2064Article in journal (Refereed)
  • 41.
    Rostedt, Anna
    et al.
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Neuroscience. neurofysiologi.
    Padua, L
    Stålberg, Erik
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Neuroscience. neurofysiologi.
    Correlation between regional myasthenic weakness and mental aspects of quality of life2006In: Eur J Neurol, Vol. 13, p. 191-193Article in journal (Refereed)
  • 42.
    Rostedt, Anna
    et al.
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Neuroscience. neurofysiologi.
    Padua, L
    Stålberg, Erik
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Neuroscience. neurofysiologi.
    Validation of the Swedish version of the disease-specific Myasthenia Gravis Questionnaire2006In: Neurol Sci, Vol. 27, p. 91-96Article in journal (Refereed)
  • 43.
    Rostedt Punga, Anna
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Clinical Neurophysiology.
    Flink, Roland
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Clinical Neurophysiology.
    Askmark, Håkan
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Clinical Neurophysiology.
    Stålberg, Erik
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Clinical Neurophysiology.
    Cholinergic neuromuscular hyperactivity in patients with myasthenia gravis seropositive for MuSK antibody2006In: Muscle and Nerve, ISSN 0148-639X, E-ISSN 1097-4598, Vol. 34, no 1, p. 111-115Article in journal (Refereed)
    Abstract [en]

    A 75-year-old man with severe oculobulbar myasthenia gravis (MG) treated with acetylcholine esterase inhibitors (AChEIs) was found to have muscle-specific tyrosine kinase (MuSK) antibodies. Neurophysiological examination displayed extra repetitive discharges after the compound motor action potential (CMAP) at low-frequency stimulation, possibly triggered by AChEI. This indicates an abnormal sensitivity to acetylcholine in patients with MuSK antibodies and may be a useful indicator of the adverse effect of AChEI treatment in these patients. Muscle Nerve, 2006

  • 44.
    Rostedt Punga, Anna
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Clinical Neurophysiology.
    Nygren, Ingela
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Neurology.
    Askmark, Håkan
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Neurology.
    Stålberg, Erik V.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Clinical Neurophysiology.
    Monozygous twins with neuromuscular transmission defects at opposite sides of the motor endplate2009In: Acta Neurologica Scandinavica, ISSN 0001-6314, E-ISSN 1600-0404, Vol. 119, no 3, p. 207-211Article in journal (Refereed)
    Abstract [en]

    Disorders affecting the postsynaptic side of the neuromuscular junction include autoimmune myasthenia gravis (MG) as well as some of the congenital myasthenic syndromes (CMS). Lambert-Eaton myasthenic syndrome (LEMS) is an acquired autoimmune neuromuscular disorder in which autoantibodies are directed against the presynaptic calcium channels. Here we describe two monozygous twin brothers: case 1 was diagnosed with an indeterminate form of acquired postsynaptic neuromuscular junction defect at age 32 and case 2 with LEMS at age 47. Case 1 presented clinically with mild generalized myasthenic weakness, neurophysiological examination revealed disturbed neuromuscular transmission along with probable myositis and serum analysis regarding antibodies against the acetylcholine receptor and muscle-specific tyrosine kinase was negative. Case 2 presented with proximal muscle fatigue accompanied by areflexia at rest and antibodies against the P/Q-type voltage-gated calcium channels were present. Neurophysiologically, case 2 had reduced baseline compound motor action potential amplitudes on neurography, decrement on low-frequency repetitive nerve stimulation (RNS) and pathological increment on high frequency RNS. To our knowledge this is the first case report of its kind and adds an intriguing contrast to the more common diagnosis of CMS in monozygous twins.

     

  • 45.
    Rostedt Punga, Anna
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Clinical Neurophysiology.
    Padua, Luca
    Stålberg, Erik
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Clinical Neurophysiology.
    Validation of the Swedish version of the disease- specific myasthenia gravis questionnaire.2006In: Neurological Sciences, ISSN 1590-1874, E-ISSN 1590-3478, Vol. 27, no 2, p. 91-96Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to translate and validate the disease-specific patient-derived Myasthenia Gravis (MG) Questionnaire to enable use among Swedish MG patients. The original Italian version of the MG Questionnaire (MGQ) was translated into Swedish and transculturally adapted. The validity and reliability was tested on 48 Swedish MG patients. We correlated MGQ scores with disease severity and with the Swedish version of the Short-Form 36-item general health survey (SF-36). Reproducibility was assessed on 18 clinically stable MG patients. A significant correlation regarding the MGQ scores was seen when correlated with physical scores of the SF-36 and the overall clinical status. Internal consistency and reproducibility was excellent. We conclude that the evaluation capacities of the Swedish MGQ are equivalent to those of the original Italian version of the MGQ. The questionnaire was successfully validated as an outcome measure also for Swedish MG patients, which is important for international multicentre clinical trials.

  • 46.
    Rostedt Punga, Anna
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience.
    Sawada, Mikio
    Stålberg, Erik V
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience.
    Electrophysiological signs and the prevalence of adverse effects of acetylcholinesterase inhibitors in patients with myasthenia gravis2007In: Muscle and Nerve, ISSN 0148-639X, E-ISSN 1097-4598, Vol. 37, no 3, p. 300-307Article in journal (Refereed)
    Abstract [en]

    The aim of this prospective study was to assess whether extra discharges (EDs), sometimes following the compound muscle action potential, could be used as a neurophysiological indicator of overdose of acetylcholinesterase inhibitors (AChEIs) in patients with myasthenia gravis (MG). The characteristics and frequency of EDs were explored and the correlation of EDs with cholinergic side effects was also determined. Twenty-two MG patients (14 women, 8 men; 61 ± 16 years of age) with daily AChEI treatment were examined. The mean disease duration was 10 years (range 2-62 years) and all patients had been treated with AChEI since MG onset. Both single and repetitive stimulation of the ulnar and accessory nerves were performed before and 60 min after oral pyridostigmine bromide (PB) administration and after additional edrophonium injection. Fatigue, side effects, and AChE activity in blood were assessed before and 60 min after PB intake. The daily dose of PB ranged from 150 to 900 mg/day. Fourteen patients (64%) experienced daily cholinergic adverse effects, and muscarinic side effects correlated with AChE activity. Eleven patients (50%) developed EDs after oral PB. Among the eight patients with daily nicotinic side effects, EDs were significantly (P < 0.05) more common. Additionally, older patients were more prone to develop cholinergic side effects and EDs. Thus, when EDs are found, patients should be asked about daily muscular symptoms, which may be related to AChEI treatment and not solely to MG. Muscle Nerve, 2007

  • 47.
    Rostedt Punga, Anna
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Clinical Neurophysiology.
    Stålberg, Erik
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Clinical Neurophysiology.
    Acetylcholinesterase inhibitors in myasthenia gravis: to be or not to be?2009In: Muscle and Nerve, ISSN 0148-639X, E-ISSN 1097-4598, Vol. 39, no 6, p. 724-728Article, review/survey (Refereed)
    Abstract [en]

    Myasthenia gravis (MG) is an autoimmune disorder usually caused by antibodies against either the acetylcholine receptor (AChR) or muscle-specific tyrosine kinase (MuSK) at the neuromuscular junction. Neuromuscular transmission failure results in muscle fatigue and weakness that can be treated symptomatically with acetylcholinesterase inhibitors (AChEIs). Long-term treatment with nonselective AChEIs may have considerable drawbacks; thus, this medication is ideally tapered when strength improves. Patients with AChR antibodies respond beneficially to treatment, whereas patients with MuSK antibodies generally do not. Recently, the selective AChEI EN101, which specifically targets the isoform of "read-through" AChE (AChE-R), has been developed and may be of importance for symptomatic relief in AChR-antibody seropositive MG. This article is a review of the mechanisms, therapeutic effects, and drawbacks, with both old and new AChEIs in MG.

  • 48.
    Sandberg, Arne
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience.
    Stålberg, Erik
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience.
    Reflexes in prior polio and their relation to weakness and anterior horn cell loss2006In: Journal of Electromyography & Kinesiology, ISSN 1050-6411, E-ISSN 1873-5711, Vol. 16, no 6, p. 611-620Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to evaluate the reflex pattern in patients with prior polio and to relate these findings to the degree of anterior horn cell (AHC) involvement and loss of muscle force.

    Twenty-five prior polio subjects were investigated with electromyography (EMG), force testing and reflex studies, which included the patellar and Achilles reflex, H-reflex, T-response and interlimb reflex (ILR).

    The clinical reflexes, H/M-ratio and T-response amplitude at rest were positively correlated with force and negatively correlated with the degree of AHC loss. The H/M-ratio was decreased compared with age matched controls.

    ILR was present in 68% of the prior polio patients but did not exist in controls. The presence of the ILR was not correlated with the degree of AHC loss or force.

    The reflex studies gave two main findings. The first is reduced excitability of monosynaptic connections in the motor neuron pool, which is related to weakness. The other is the presence of ILR as an indicator of interneuronal hyper-excitability, which is not related to weakness.

  • 49.
    Sanders, Donald B.
    et al.
    Duke Univ, Med Ctr, Box 3403, Durham, NC 27710 USA.
    Arimura, Kimiyoshi
    Kagoshima Univ, Grad Sch Med & Dent Sci, Dept Neurol & Geriatr, Kagoshima, Japan.
    Cui, LiYing
    Chinese Acad Med Sci, Peking Union Med Coll Hosp, Beijing, Peoples R China.
    Ertas, Mustafa
    Istanbul Fac Med, Istanbul, Turkey.
    Farrugia, Maria Elena
    Inst Neurol Sci, Glasgow, Lanark, Scotland.
    Gilchrist, James
    Southern Illinois Univ, Sch Med, Springfield, IL USA.
    Kouyoumdjian, Joao Aris
    Fac Med Sao Jose Rio Preto FAMERP, Sao Paulo, Brazil.
    Padua, Luca
    Univ Cattolica Sacro Cuore, Fdn Policlin Univ Agostino Gemelli IRCCS, Dept Geriatr Neurosci & Orthopaed, Rome, Italy.
    Pitt, Matthew
    Great Ormond St Hosp Sick Children, Dept Clin Neurophysiol, London, England.
    Stålberg, Erik
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Rostedt Punga: Clinical Neurophysiology.
    Guidelines for single fiber EMG2019In: Clinical Neurophysiology, ISSN 1388-2457, E-ISSN 1872-8952, Vol. 130, no 8, p. 1417-1439Article in journal (Refereed)
    Abstract [en]

    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. This process continued until a consensus was reached. Donald Sanders and Erik Stalberg then edited the final document.

  • 50. Schreurs, Annabel
    et al.
    Stålberg, Erik V.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Clinical Neurophysiology.
    Rostedt Punga, Anna
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Clinical Neurophysiology.
    Indication of peripheral nerve hyperexcitability in adult-onset subacute sclerosing panencephalitis (SSPE)2008In: Neurological Sciences, ISSN 1590-1874, E-ISSN 1590-3478, Vol. 29, no 2, p. 121-124Article in journal (Refereed)
    Abstract [en]

    Subacute sclerosing panencephalitis (SSPE) is a rare chronic, progressive encephalitis that affects primarily children and young adults, caused by a persistent infection of immune-resistant measles virus. Diagnostic hallmarks include widespread cortical dysfunction on EEG, myoclonus, white matter abnormalities on neuroradiological examination and the presence of IgG antimeasles antibodies in the cerebrospinal fluid. We present the first case of SSPE with signs of peripheral nerve hyperexcitability, observed as extra discharges following the compound motor action potential at motor nerve stimulation. In addition we demonstrate the importance of SSPE in the differential diagnosis of adult patients with psychiatric and neurological symptoms.

     

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