Spectral analysis of EEG in etiological assessment of patients with transient neurological deficits

Abstract

ObjectiveDifferentiating transient ischemic attack from stroke mimics may be difficult. Besides clinical evaluation and brain imaging, electroencephalography (EEG) may be a useful diagnostic tool. MethodsWe conducted spectral analysis on 67 EEG of patients who had presented a transient neurological deficit (TND) within the previous seven days. Expert clinicians provided the final diagnosis: transient ischemic attack, migraine with aura, focal seizure or “other”. We first calculated the relative power of the four EEG frequency bands (delta, theta, alpha and beta), in the whole hemisphere, then, according to the clinical symptoms, in the relevant electrodes of the symptomatic hemisphere. Finally, we calculated the relative power ratio between symptomatic and asymptomatic hemispheres. ResultsMedian age was 60.6 years (57% females). The etiological diagnosis was transient ischemic attack (27%), migraine with aura (11%), focal seizures (22%) and “other” (40%). We did not find significant differences in the theta and delta relative power analysis between groups. Over the symptomatic hemisphere only, we found a significant increase of the alpha relative power (p = 0.0026, p < 0.0001, p = 0.0014) in the migraine group compared to transient ischemic attack, migraine and focal seizures groups, and a significant decrease of the beta relative power (p = 0.0034, p = 0.0016, p = 0.0005) compared to the same groups. ConclusionsMigraine with aura presents a discriminative EEG relative power in comparison to transient neurological deficits of other origins. To further investigate the additive diagnosis value of EEG in other TND, future studies should be performed with an EEG obtained within the first 24 h after the onset of symptoms. SignificanceSpectral EEG analysis discriminates migraine with aura groups from other groups, but not at the individual level.