Reproducibility and clinical relevance of quantitative EEG parameters in cerebral ischemia: a basic approach

Clin Neurophysiol. 2009 May;120(5):845-55. doi: 10.1016/j.clinph.2009.02.171. Epub 2009 Apr 16.


Objective: To investigate reproducibility and clinical relevance of quantitative EEG parameters in ischemic cerebrovascular disease.

Methods: EEG was recorded in 31 patients suffering from subacute ischemic cerebrovascular disease. Ten age-matched control subjects were included as a reference group. Intra-recording, intrarater and interrater reproducibility was calculated for standard EEG measures and for a pair wise derived Brain Symmetry Index (pdBSI). Correlations between EEG parameters, clinical status and volume of ischemia on diffusion weighted imaging (DWI) were calculated.

Results: pdBSI was sensitive to asymmetry in the amplitude and frequency domain in a random white noise model and in a simulated sinusoidal model. Minimal Cronbach alpha for intra-recording, intra- and inter-rater reproducibility ranged between 0.95 and 0.99 for standard spectral parameters and between 0.96 and 0.99 for pdBSI. We found a significant difference in pdBSI between stroke patients and control or TIA (p=0.0003). pdBSI correlated significantly with NIH stroke scale at admission and DWI volume across different levels of stroke probability (Spearman's rho=0.64-0.70 and 0.79-0.84, respectively, p<0.00001 for both).

Conclusions: pdBSI displays high multilevel reproducibility and reliably discriminates between stroke and TIA patients or control subjects, and correlates significantly with clinical and radiological status.

Significance: Based on this methodological analysis, reliable EEG parameters can be evaluated in a general stroke population for clinically relevant state and outcome measures.

MeSH terms

  • Aged
  • Aged, 80 and over
  • Brain Ischemia / diagnosis*
  • Brain Ischemia / physiopathology*
  • Cerebral Cortex / physiopathology*
  • Computer Simulation
  • Diagnosis, Differential
  • Electroencephalography / methods*
  • Evoked Potentials / physiology*
  • Female
  • Humans
  • Ischemic Attack, Transient / diagnosis
  • Ischemic Attack, Transient / physiopathology
  • Male
  • Middle Aged
  • Predictive Value of Tests
  • Reproducibility of Results
  • Signal Processing, Computer-Assisted
  • Stroke / diagnosis
  • Stroke / physiopathology