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Título

FUNCTIONAL AND STRUCTURAL ANALYSIS OF PATIENTS WITH LATERALIZED PERIODIC DISCHARGES

Resumo

Introduction: Lateralized periodic discharges (LPDs) are a common EEG pattern in critically ill patients. They are considered in interictal-ictal continuum and the mechanism is still under investigation. In this study neuroimaging and clinical neurophysiology were combined to investigate LPDs features.

Methods: 11 patients were investigated. All subjects were submitted to high resolution CT (5 patients) or MRI (6 patients) and EEG. Brain scans were automatically segmented and normalized into a standard space. All patients had LPDs visually identified in the EEG. For each patient, periodic discharges were automatically selected and averaged. A tridimensional image of the source map using deterministic algorithm was obtained. Finally, statistical analysis was conducted searching for correlation between the two methods (neuroimaging and EEG).

Results: Mean age of the patients was 5817 (34-78, 5 women). Mean number of discharges analyzed was 173262 (22-692). The etiology of LPDs was encephalopathy (n=5), status epilepticus (n=4), encephalitis (n=1) and structural (n=1). Statistical analysis showed areas of positive correlation between neuroimaging and LPDs mainly in the posterior quadrants involving left inferior occipital gyrus (p<0.001, 2390mm3) and the right middle temporal gyrus (p<0.001, 1919mm3).

Conclusion: It was demonstrated that areas of cortical atrophy were associated with the LPDs discharges despite of the multiple etiology. The areas disclosed are in circulatory border zones which are vulnerable to critical situations. These findings may ultimately lead to synaptic failure probably generating the onset and/or continuation of LPDs.