Age-dependent decline in motor evoked potential (MEP) amplitude: with a comment on changes in Parkinson's disease

Electroencephalogr Clin Neurophysiol. 1991 Jun;81(3):209-15. doi: 10.1016/0168-5597(91)90074-8.

Abstract

Peak-to-peak measurement of the maximum amplitude motor evoked potential (MAXMEP) elicited by 20 consecutive transcranial magnetic stimuli recorded from the contracting thenar and hypothenar muscles measured 9.8 +/- 2.0 mV and 7.25 +/- 2.9 mV respectively (P less than 0.01). The ratio of MAXMEP/CMAP measured 92.6 +/- 25.8% and 54.8 +/- 12.3% respectively (P less than 0.001). Repeat studies showed good individual reproducibility. Amplitudes declined linearly with age (r = -0.836 for thenar MAXMEP P less than 0.001). It is argued that MAXMEP related to age is more meaningful than the MEP/CMAP wave ratio and is proportional to the number of fast conducting cortical motor neurons excited. In 7/18 patients with Parkinson's disease (PD) MAXMEP was increased; in 2 other patients MAXMEP was decreased for their age.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Age Factors
  • Aged
  • Aged, 80 and over
  • Electromyography
  • Evoked Potentials
  • Female
  • Humans
  • Magnetics
  • Male
  • Middle Aged
  • Motor Cortex / physiology
  • Motor Cortex / physiopathology*
  • Motor Neurons / physiology
  • Muscle Contraction
  • Muscles / physiology
  • Muscles / physiopathology*
  • Neural Conduction
  • Parkinson Disease / physiopathology*
  • Regression Analysis
  • Reproducibility of Results
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