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Classification and evaluation of myoclonus

Author
John N Caviness, MD
Section Editor
Howard I Hurtig, MD
Deputy Editor
John F Dashe, MD, PhD

INTRODUCTION AND DEFINITION

Myoclonus is a clinical sign that is characterized by brief, shock-like, involuntary movements caused by muscular contractions or inhibitions [1]. Muscular contractions produce positive myoclonus, whereas muscular inhibitions produce negative myoclonus (ie, asterixis). Patients will usually describe myoclonus as consisting of "jerks," "shakes," or "spasms."

Myoclonic movements have many possible etiologies, anatomic sources, and pathophysiologic features [2]. Myoclonus may be classified by clinical presentation, examination findings, clinical neurophysiology testing, and etiology.

This topic will review the classification and evaluation of myoclonus. Treatment is discussed separately. (See "Treatment of myoclonus".)

ANATOMIC AND PHYSIOLOGIC CLASSIFICATION

In addition to the clinical and etiologic classification discussed below, myoclonus can be classified by the localization of the physiologic mechanism that generates it (table 1). These anatomic-physiologic categories are as follows:

Cortical

                               

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Literature review current through: Nov 2016. | This topic last updated: Wed Nov 16 00:00:00 GMT+00:00 2016.
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References
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  1. Marsden CD, Hallett M, Fahn S. The nosology and pathophysiology of myoclonus. In: Movement Disorders, Marsden CD, Fahn S (Eds), Butterworths, London 1982. p.196.
  2. Caviness JN, Brown P. Myoclonus: current concepts and recent advances. Lancet Neurol 2004; 3:598.
  3. Caviness JN. Clinical Neurophysiology of Myoclonus. In: Handbook of Clinical Neurophysiology, Vol 1: Movement Disorders, Hallett M (Ed), Elsevier, Amsterdam 2003. p.521.
  4. Brown P, Day BL, Rothwell JC, et al. Intrahemispheric and interhemispheric spread of cerebral cortical myoclonic activity and its relevance to epilepsy. Brain 1991; 114 ( Pt 5):2333.
  5. Guerrini R, Bonanni P, Parmeggiani L, et al. Pathophysiology of myoclonic epilepsies. Adv Neurol 2005; 95:23.
  6. Hitomi T, Ikeda A, Matsumoto R, et al. Generators and temporal succession of giant somatosensory evoked potentials in cortical reflex myoclonus: epicortical recording from sensorimotor cortex. Clin Neurophysiol 2006; 117:1481.
  7. Ikeda A, Kakigi R, Funai N, et al. Cortical tremor: a variant of cortical reflex myoclonus. Neurology 1990; 40:1561.
  8. Snead OC 3rd. Basic mechanisms of generalized absence seizures. Ann Neurol 1995; 37:146.
  9. Nitschke MF, Erdmann C, Trillenberg P, et al. Functional MRI reveals activation of a subcortical network in a 5-year-old girl with genetically confirmed myoclonus-dystonia. Neuropediatrics 2006; 37:79.
  10. Caviness JN, Alving LI, Maraganore DM, et al. The incidence and prevalence of myoclonus in Olmsted County, Minnesota. Mayo Clin Proc 1999; 74:565.
  11. Lugaresi E, Cirignotta F, Coccagna G, Montagna P. Nocturnal myoclonus and restless legs syndrome. Adv Neurol 1986; 43:295.
  12. Marsden CD, Fahn S. Problems in the dyskinesias. In: Movement Disorders, Marsden CE, Fahn S (Eds), Butterworths, London 1987. Vol 2, p.305.
  13. Krueger BR. Restless legs syndrome and periodic movements of sleep. Mayo Clin Proc 1990; 65:999.
  14. Bressman S, Fahn S. Essential myoclonus. Adv Neurol 1986; 43:287.
  15. Wakata N, Sugimoto H, Iguchi H, et al. A case of voluntary palatal myoclonus with ear click: relationship between palatal myoclonus and click. Eur Neurol 2002; 48:52.
  16. Fabiani G, Teive HA, Sá D, et al. Palatal myoclonus: report of two cases. Arq Neuropsiquiatr 2000; 58:901.
  17. Kutukcu Y, Imirzalioglu N, Odabasi Z, et al. Essential palatal myoclonus in monozygotic male twins. J Neurol 2003; 250:885.
  18. Bento RF, Sanchez TG, Miniti A, Tedesco-Marchesi AJ. Continuous, high-frequency objective tinnitus caused by middle ear myoclonus. Ear Nose Throat J 1998; 77:814.
  19. Golz A, Fradis M, Netzer A, et al. Bilateral tinnitus due to middle-ear myoclonus. Int Tinnitus J 2003; 9:52.
  20. Golz A, Fradis M, Martzu D, et al. Stapedius muscle myoclonus. Ann Otol Rhinol Laryngol 2003; 112:522.
  21. Oliveira CA, Negreiros Júnior J, Cavalcante IC, et al. Palatal and middle-ear myoclonus: a cause for objective tinnitus. Int Tinnitus J 2003; 9:37.
  22. Bhimrao SK, Masterson L, Baguley D. Systematic review of management strategies for middle ear myoclonus. Otolaryngol Head Neck Surg 2012; 146:698.
  23. Mahloudji M, Pikielny RT. Hereditary essential myoclonus. Brain 1967; 90:669.
  24. Kinugawa K, Vidailhet M, Clot F, et al. Myoclonus-dystonia: an update. Mov Disord 2009; 24:479.
  25. Roze E, Apartis E, Clot F, et al. Myoclonus-dystonia: clinical and electrophysiologic pattern related to SGCE mutations. Neurology 2008; 70:1010.
  26. Raymond D, Saunders-Pullman R, de Carvalho Aguiar P, et al. Phenotypic spectrum and sex effects in eleven myoclonus-dystonia families with epsilon-sarcoglycan mutations. Mov Disord 2008; 23:588.
  27. Foncke EM, Gerrits MC, van Ruissen F, et al. Distal myoclonus and late onset in a large Dutch family with myoclonus-dystonia. Neurology 2006; 67:1677.
  28. Kurlan R, Behr J, Medved L, Shoulson I. Myoclonus and dystonia: a family study. Adv Neurol 1988; 50:385.
  29. Quinn NP. Essential myoclonus and myoclonic dystonia. Mov Disord 1996; 11:119.
  30. Asmus F, Gasser T. Inherited myoclonus-dystonia. Adv Neurol 2004; 94:113.
  31. Han F, Lang AE, Racacho L, et al. Mutations in the epsilon-sarcoglycan gene found to be uncommon in seven myoclonus-dystonia families. Neurology 2003; 61:244.
  32. Schüle B, Kock N, Svetel M, et al. Genetic heterogeneity in ten families with myoclonus-dystonia. J Neurol Neurosurg Psychiatry 2004; 75:1181.
  33. Tezenas du Montcel S, Clot F, Vidailhet M, et al. Epsilon sarcoglycan mutations and phenotype in French patients with myoclonic syndromes. J Med Genet 2006; 43:394.
  34. Ritz K, Gerrits MC, Foncke EM, et al. Myoclonus-dystonia: clinical and genetic evaluation of a large cohort. J Neurol Neurosurg Psychiatry 2009; 80:653.
  35. Groen JL, Ritz K, Jalalzadeh H, et al. RELN rare variants in myoclonus-dystonia. Mov Disord 2015; 30:415.
  36. Groen JL, Andrade A, Ritz K, et al. CACNA1B mutation is linked to unique myoclonus-dystonia syndrome. Hum Mol Genet 2015; 24:987.
  37. Stamelou M, Mencacci NE, Cordivari C, et al. Myoclonus-dystonia syndrome due to tyrosine hydroxylase deficiency. Neurology 2012; 79:435.
  38. Grimes DA, Han F, Lang AE, et al. A novel locus for inherited myoclonus-dystonia on 18p11. Neurology 2002; 59:1183.
  39. Saunders-Pullman R, Shriberg J, Heiman G, et al. Myoclonus dystonia: possible association with obsessive-compulsive disorder and alcohol dependence. Neurology 2002; 58:242.
  40. Hess CW, Raymond D, Aguiar Pde C, et al. Myoclonus-dystonia, obsessive-compulsive disorder, and alcohol dependence in SGCE mutation carriers. Neurology 2007; 68:522.
  41. Asmus F, Salih F, Hjermind LE, et al. Myoclonus-dystonia due to genomic deletions in the epsilon-sarcoglycan gene. Ann Neurol 2005; 58:792.
  42. Peall KJ, Smith DJ, Kurian MA, et al. SGCE mutations cause psychiatric disorders: clinical and genetic characterization. Brain 2013; 136:294.
  43. Müller B, Hedrich K, Kock N, et al. Evidence that paternal expression of the epsilon-sarcoglycan gene accounts for reduced penetrance in myoclonus-dystonia. Am J Hum Genet 2002; 71:1303.
  44. Chan P, Gonzalez-Maeso J, Ruf F, et al. Epsilon-sarcoglycan immunoreactivity and mRNA expression in mouse brain. J Comp Neurol 2005; 482:50.
  45. Thomas JE, Reagan TJ, Klass DW. Epilepsia partialis continua. A review of 32 cases. Arch Neurol 1977; 34:266.
  46. Delgado-Escueta AV, Medina MT, Bai DS, et al. Genetics of idiopathic myoclonic epilepsies: an overview. Adv Neurol 2002; 89:161.
  47. Kanai K, Hirose S, Oguni H, et al. Effect of localization of missense mutations in SCN1A on epilepsy phenotype severity. Neurology 2004; 63:329.
  48. Striano P, Zara F, Striano S. Autosomal dominant cortical tremor, myoclonus and epilepsy: many syndromes, one phenotype. Acta Neurol Scand 2005; 111:211.
  49. van Rootselaar AF, van Schaik IN, van den Maagdenberg AM, et al. Familial cortical myoclonic tremor with epilepsy: a single syndromic classification for a group of pedigrees bearing common features. Mov Disord 2005; 20:665.
  50. Coppola A, Santulli L, Del Gaudio L, et al. Natural history and long-term evolution in families with autosomal dominant cortical tremor, myoclonus, and epilepsy. Epilepsia 2011; 52:1245.
  51. Cen Z, Huang C, Yin H, et al. Clinical and neurophysiological features of familial cortical myoclonic tremor with epilepsy. Mov Disord 2016.
  52. Alvarez M, Caviness JN. Primary progressive myoclonus of aging. Mov Disord 2008; 23:1658.
  53. Russell JF, Steckley JL, Coppola G, et al. Familial cortical myoclonus with a mutation in NOL3. Ann Neurol 2012; 72:175.
  54. Shibasaki H, Hallett M. Electrophysiological studies of myoclonus. Muscle Nerve 2005; 31:157.