Abnormal reactivity of the approximately 20-Hz motor cortex rhythm in Unverricht Lundborg type progressive myoclonus epilepsy

Neuroimage. 2000 Dec;12(6):707-12. doi: 10.1006/nimg.2000.0660.


The approximately 20-Hz component of the human mu rhythm originates predominantly in the primary motor cortex. We monitored with a whole-scalp neuromagnetometer the reactivity of the approximately 20-Hz rhythm as an index of the functional state of the primary motor cortex in seven patients suffering from Unverricht-Lundborg type (ULD) progressive myoclonus epilepsy (PME) and in seven healthy control subjects. In patients, the motor cortex rhythm was on average 5 Hz lower in frequency and its strength was double compared with controls. To study reactivity of the approximately 20-Hz rhythm, left and right median nerves were stimulated alternately at wrists. In controls, these stimuli elicited a small transient decrease, followed by a strong increase ("rebound") of the approximately 20-Hz level. In contrast, the patients showed no significant rebounds of the rhythm. As the approximately 20-Hz rebounds apparently reflect increased cortical inhibition, our results indicate that peripheral stimuli excite motor cortex for prolonged periods in patients with ULD.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Brain Mapping
  • Dominance, Cerebral / physiology
  • Electric Stimulation
  • Female
  • Humans
  • Magnetoencephalography*
  • Male
  • Median Nerve / physiopathology
  • Motor Cortex / physiology*
  • Myoclonic Epilepsies, Progressive / diagnosis
  • Myoclonic Epilepsies, Progressive / genetics
  • Myoclonic Epilepsies, Progressive / physiopathology*
  • Neural Inhibition / physiology
  • Somatosensory Cortex / physiopathology