Event related desynchronisation predicts functional propriospinal myoclonus

Parkinsonism Relat Disord. 2016 Oct;31:116-118. doi: 10.1016/j.parkreldis.2016.07.010. Epub 2016 Jul 22.


Objective: Recent diagnostic criteria for functional movement disorders have proposed a "laboratory supported" level of diagnostic certainty where the clinical diagnosis is supported by a positive test. For functional myoclonus the Bereitschaftspotential (BP) is generally accepted as a positive laboratory test. We hypothesised that a different EEG measure, event-related desynchronisation (ERD), might be more effective.

Methods: We analysed 20 patients with functional propriospinal myoclonus (fPSM) and 9 controls with organic myoclonus and performed back-averaging for BPs plus time-frequency decomposition to assess ERD and calculated sensitivity and specificity for both techniques.

Results: The BP was present in only 25% of patients with fPSM while the majority showed a significant ERD (mean 38 Hz; sensitivity 65%). ERD was significant at the group level (p < 0.001), but not the BP (p > 0.05). Both BP and ERD were absent in our control group.

Conclusion: ERD in high-beta may be a useful new test for positive diagnosis of functional myoclonus.

Keywords: EEG; Myoclonus.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Contingent Negative Variation / physiology*
  • Electroencephalography
  • Electromyography
  • Evoked Potentials / physiology*
  • Female
  • Humans
  • Male
  • Middle Aged
  • Myoclonus / physiopathology*
  • Young Adult