Quantitative EEG as a diagnostic tool in patients with head injury and posttraumatic epilepsy

Abstract

We investigated by means of quantitative EEG (qEEG) analysis EEG traces of patients with brain trauma (with and without posttraumatic epilepsy) with respect to control group. The aim of our work was to determine if there are qEEG parameters sensible for traumatic and epileptic changes of brain tissue and how these parameters change after hyperventilation (HV), one of the routine methods for cerebral activation. On 69 patients (36 patients with posttraumatic epilepsy (PTE) and 33 without PTE) and control group of healthy patients (34 subjects), EEG registration and analysis was performed before and after HV: Fast Fourier analysis was performed on 16-s segments and amplitude mean value was calculated in ten frequency ranges in four EEG projections. HV induced significant differences in F7-C3 projection in all three groups of patients, so we analysed differences for each frequency range in F7-C3 projection for all three groups of patients. Significant differences are registered between group of healthy patients and patients with PTE in intervals of low frequencies (0-3 Hz) and high frequencies (6-11 Hz). After HV statistically significant difference is observed in all frequency ranges. Factor “epilepsy” (patients with trauma without PTE vs. patients with PTE) marks significant differences in high frequency ranges (6-11 Hz). For this factor, HV expands the group of significantly different frequency ranges towards the low frequency ranges. Consequently, the most sensitive frequency ranges for factor “epilepsy” are in high frequency range. There are no significant differences in any frequency ranges for factor “trauma” (control group of subjects vs. patients with brain trauma without PTE) before HV. After HV the significant differences appear in the range of low (0-2 Hz) and high frequencies (7-11 Hz). qEEG analysis is a diagnostic tool of potentially high selectivity in differential diagnosis of patients with brain trauma with or without PTE.