Spectral EEG analysis in refractory Juvenile Myoclonic Epilepsy: a new biomarker in epilepsy

Objective: The aim of this study was to investigate quantitative analysis of background EEG activity (spectral analysis) of patients with refractory juvenile myoclonic epilepsy (rJME). Methods: to correlate clinical and standard EEG abnormalities with spectral EEG findings in 19 patients with rJME in two different physiological states, morning and evening. The EEG analysis included absolute power (AP) of delta, theta, alpha and beta bands. The Z scores were calculated by comparison with population parameters based one the age-dependent regression function. Was evaluated theta/alpha index and compared to intelligence quotient (IQ). Results: 38 samples, 19 in morning sample (MS) and 19 in evening sample (ES). I have found < 50% agreement between visual and quantitative EEG. Global absolute power, with or without Z scores, showed no statistically significant difference (p > 0.05) in all the frequencies between the two groups; a positive correlation is seen in theta and beta bands between the two states. All the samples were characterised by increased global mean AP in delta and theta bands, more evident in the MS group and beta band more evident in the ES group, but this difference is no statistically significant between the two physiological states. There was an increase in mean AP Z scores which was evident in left frontal leads in both groups. A positive correlation is seen between theta/alpha index in MS and ES group. In addition, I have found that increase theta/alpha index > 1.50 is associated with a decrease in cognitive IQ scores. Conclusions: these results suggest that is not significant difference between physiological states, morning or evening, in patients with rJME. In addition I found clear evidence, during background activity in patients with rJME, of focal predominance in left frontal regions. The pathogenesis of JME is still unclear, but my sample exhibit focal abnormalities by spectral analysis, which provide convincing evidence for abnormalities in thalamocortical circuits. This study confirms that theta/alpha index represent a good marker for cognitive deficit in all of patients with frontal lobe disfunction and that spectral EEG analysis, as functional neuroimaging, can be used as biomarker of an altered neurobiological process in epilepsy.