Abstract
Despite the increasing availability of genetic panels and their diminishing cost genetic screening for myasthenic conditions in children remains difficult. Additionally some children with undoubted myasthenic conditions have yet to be genetically characterised. For this reason a neurophysiological test for the diagnosis of disorders of the neuromuscular junction (NMJ) is valuable. Of the options available repetitive nerve stimulation up (RNS) is relatively insensitive and uncomfortable and reliance on a form of single fibre EMG (SFEMG) is essential. Volitional SFEMG presents formidable challenges in children and is unlikely to be successful in any child under the age of eight years. Stimulation techniques increase the feasibility of studies in children. A modification of stimulation SFEMG using concentric needle electrodes has been developed. Because multiple motor units are stimulated true single-fibre potentials are not seen with this technique and we therefore describe the technique as Stimulated Potential Analysis using Concentric needle Electrodes under the acronym SPACE. Examinations are conducted on orbicularis oculi being the most sensitive muscle in most myasthenic conditions. With the use of local anaesthetic it is possible to effect successful examination in most children. Monopolar needles are placed near the facial nerve as it crosses the zygomatic arch with the potentials recorded from orbicularis oculi. The use of peak detection algorithms on most EMG machines allows some quantification of the results producing a value for the Mean Consecutive Difference (MCD) and these are unaffected by the high-frequency filter used. Quantification of the MCD becomes increasingly difficult with increasing abnormality of the underlying NMJ. Normative data have been derived from the extrapolated norms (e-norms) technique. When applied to a large cohort of patients the technique demonstrates sensitivity 84%, specificity 71%, negative predictive value 96%, and positive predictive value 36% for the diagnosis of myasthenia. Specificity can be further enhanced if those conditions caused by a neurogenic abnormality are excluded. The technique is within the competence of any trained clinical neurophysiologist and is well tolerated by patients and parents alike. It is an important neurophysiological technique for the diagnosis of neuromuscular junction abnormality.
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References
Beeson D. Congenital myasthenic syndromes: recent advances. Curr Opin Neurol. 2016;29:565–71.
Ravenscroft G, Davis MR, Lamont P, Forrest A, Laing NG. New era in genetics of early-onset muscle disease: breakthroughs and challenges. Semin Cell Dev Biol. 2017;64:160–70.
Shelton GD. Myasthenia gravis and congenital myasthenic syndromes in dogs and cats: a history and mini-review. Neuromuscul Disord. 2016;26:331–4.
Engel AG, Shen XM, Selcen D, Sine SM. Congenital myasthenic syndromes: pathogenesis, diagnosis, and treatment. Lancet Neurol. 2015;14:420–34.
Eymard B, Hantai D, Fournier E, Nicole S, Sternberg D, Richard P, Fardeau M. Congenital myasthenic syndromes; French experience. Bull Acad Natl Med. 2014;198:257–70.
Rodriguez Cruz PM, Palace J, Beeson D. Congenital myasthenic syndromes and the neuromuscular junction. Curr Opin Neurol. 2014;27:566–75.
Eymard B, Hantai D, Estournet B. Congenital myasthenic syndromes. Handb Clin Neurol. 2013;113:1469–80.
Finlayson S, Beeson D, Palace J. Congenital myasthenic syndromes: an update. Pract Neurol. 2013;13:80–91.
Hantai D, Nicole S, Eymard B. Congenital myasthenic syndromes: an update. Curr Opin Neurol. 2013;26:561–8.
Engel AG. Current status of the congenital myasthenic syndromes. Neuromuscul Disord. 2012;22:99–111.
Lorenzoni PJ, Scola RH, Kay CS, Werneck LC. Congenital myasthenic syndrome: a brief review. Pediatr Neurol. 2012;46:141–8.
Nance JR, Dowling JJ, Gibbs EM, Bonnemann CG. Congenital myopathies: an update. Curr Neurol Neurosci Rep. 2012;12:165–74.
Barisic N, Chaouch A, Muller JS, Lochmuller H. Genetic heterogeneity and pathophysiological mechanisms in congenital myasthenic syndromes. Eur J Paediatr Neurol. 2011;15:189–96.
Pitt M. Neurophysiological strategies for the diagnosis of disorders of the neuromuscular junction in children. Dev Med Child Neurol. 2008;50:328–33.
Trontelj JV, Khuraibet A, Mihelin M. The jitter in stimulated orbicularis oculi muscle: technique and normal values. J Neurol Neurosurg Psychiatry. 1988;51:814–9.
Trontelj JV. Stimulation SFEMG in myasthenia gravis. Muscle Nerve. 1990;13:458–9.
Payan J. The blanket principle: a technical note. Muscle Nerve. 1978;1:423–6.
Parr JR, Andrew MJ, Finnis M, Beeson D, Vincent A, Jayawant S. How common is childhood myasthenia? The UK incidence and prevalence of autoimmune and congenital myasthenia. Arch Dis Child. 2014;99:539–42.
Patel A, Gosk M, Pitt M. The effect of different low-frequency filters on concentric needle jitter in stimulated orbicularis oculi. Muscle Nerve. 2016;54:317–9.
Rodriguez Cruz PM, Belaya K, Basiri K, Sedghi M, Farrugia ME, Holton JL, Liu WW, Maxwell S, Petty R, Walls TJ, Kennett R, Pitt M, Sarkozy A, Parton M, Lochmuller H, Muntoni F, Palace J, Beeson D. Clinical features of the myasthenic syndrome arising from mutations in GMPPB. J Neurol Neurosurg Psychiatry. 2016;87:802–9.
Belaya K, Rodriguez Cruz PM, Liu WW, Maxwell S, McGowan S, Farrugia ME, Petty R, Walls TJ, Sedghi M, Basiri K, Yue WW, Sarkozy A, Bertoli M, Pitt M, Kennett R, Schaefer A, Bushby K, Parton M, Lochmuller H, Palace J, Muntoni F, Beeson D. Mutations in GMPPB cause congenital myasthenic syndrome and bridge myasthenic disorders with dystroglycanopathies. Brain. 2015;138:2493–504.
Klein A, Robb S, Rushing E, Liu WW, Belaya K, Beeson D. Congenital Myasthenic syndrome caused by mutations in DPAGT. Neuromuscul Disord. 2015;25:253–6.
Selcen D, Shen XM, Brengman J, Li Y, Stans AA, Wieben E, Engel AG. DPAGT1 myasthenia and myopathy: genetic, phenotypic, and expression studies. Neurology. 2014;82:1822–30.
Ertas M, Baslo MB, Yildiz N, Yazici J, Oge AE. Concentric needle electrode for neuromuscular jitter analysis. Muscle Nerve. 2000;23:715–9.
Sanders DB. Measuring jitter with concentric needle electrodes. Muscle Nerve. 2013;47:317–8.
Stalberg E. Jitter analysis with concentric needle electrodes. Ann N Y Acad Sci. 2012;1274:77–85.
Stalberg EV, Trontelj JV, Sanders DB. Single fibre EMG. Fiskebackskil, Lysekil: Edshagen Publishing House; 2010.
Gilchrist JM. Single fiber EMG reference values: a collaborative effort. Ad hoc committee of the AAEM special interest group on single fiber EMG. Muscle Nerve. 1992;15:151–61.
Kouyoumdjian JA, Stalberg EV. Reference jitter values for concentric needle electrodes in voluntarily activated extensor digitorum communis and orbicularis oculi muscles. Muscle Nerve. 2008;37:694–9.
Kouyoumdjian JA, Stalberg EV. Concentric needle jitter on stimulated orbicularis oculi in 50 healthy subjects. Clin Neurophysiol. 2011;122:617–22.
Sarrigiannis PG, Kennett RP, Read S, Farrugia ME. Single-fiber EMG with a concentric needle electrode: validation in myasthenia gravis. Muscle Nerve. 2006;33:61–5.
Stalberg E, Trontelj JV. Single fiber electromyography studies in healthy and disease muscle. New York: Raven Press Ltd; 1994.
Trontelj JV, Fernandez JM. Single fiber EMG in juvenile idiopathic scoliosis. Muscle Nerve. 1988;11:297–300.
Valls-Canals J, Povedano M, Montero J, Pradas J. Stimulated single-fiber EMG of the frontalis and orbicularis oculi muscles in ocular myasthenia gravis. Muscle Nerve. 2003;28:501–3.
Jabre JF, Pitt MC, Deeb J, Chui KK. E-norms: a method to extrapolate reference values from a laboratory population. J Clin Neurophysiol. 2015;32:265–70.
Pitt MC, Jabre JF. Determining jitter values in the very young by use of the e-norms methodology. Muscle Nerve. 2017;55(1):51–4.
Verma S, Lin J. Stimulated jitter analysis for the evaluation of neuromuscular junction disorders in children. Muscle Nerve. 2016;53:471–2.
Verma S, Lin J, Barkhaus PE. Stimulated jitter analysis in the early diagnosis of infant botulism. Muscle Nerve. 2015;52:309–10.
Pitt MC, McHugh JC, Deeb J, Smith RA. Assessing neuromuscular junction stability from stimulated EMG in children. Clin Neurophysiol. 2017;128:290–6.
Lyu RK, Cheng SY, Tang LM. Electrodiagnostic studies in myasthenia gravis. Changgeng Yi Xue Za Zhi. 1993;16:164–9.
SJ O, Kim DE, Kuruoglu R, Bradley RJ, Dwyer D. Diagnostic sensitivity of the laboratory tests in myasthenia gravis. Muscle Nerve. 1992;15:720–4.
Sanders DB, Howard JF Jr. AAEE minimonograph #25: single-fiber electromyography in myasthenia gravis. Muscle Nerve. 1986;9:809–19.
Illingworth MA, Main M, Pitt M, Feng L, Sewry CA, Gunny R, Vorstman E, Beeson D, Manzur A, Muntoni F, Robb SA. RYR1-related congenital myopathy with fatigable weakness, responding to pyridostigimine. Neuromuscul Disord. 2014;24:707–12.
Munot P, Lashley D, Jungbluth H, Feng L, Pitt M, Robb SA, Palace J, Jayawant S, Kennet R, Beeson D, Cullup T, Abbs S, Laing N, Sewry C, Muntoni F. Congenital fibre type disproportion associated with mutations in the tropomyosin 3 (TPM3) gene mimicking congenital myasthenia. Neuromuscul Disord. 2010;20:796–800.
Robb SA, Sewry CA, Dowling JJ, Feng L, Cullup T, Lillis S, Abbs S, Lees MM, Laporte J, Manzur AY, Knight RK, Mills KR, Pike MG, Kress W, Beeson D, Jungbluth H, Pitt MC, Muntoni F. Impaired neuromuscular transmission and response to acetylcholinesterase inhibitors in centronuclear myopathies. Neuromuscul Disord. 2011;21:379–86.
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Pitt, M. (2017). The Use of Stimulated EMG in the Diagnosis of Neuromuscular Junction Abnormality. In: McMillan, H., Kang, P. (eds) Pediatric Electromyography. Springer, Cham. https://doi.org/10.1007/978-3-319-61361-1_10
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DOI: https://doi.org/10.1007/978-3-319-61361-1_10
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