[Show abstract][Hide abstract] ABSTRACT: We investigated the possibility of differential diagnosis of patients with epileptic seizures (ES) and patients with psychogenic nonepileptic seizures (PNES) through an advanced analysis of the dynamics of the patients' scalp EEGs. The underlying principle was the presence of resetting of brain's preictal spatiotemporal entrainment following onset of ES and the absence of resetting following PNES. Long-term (days) scalp EEGs recorded from five patients with ES and six patients with PNES were analyzed. It was found that: (1) Preictal entrainment of brain sites was reset at ES (P<0.05) in four of the five patients with ES, and not reset (P=0.28) in the fifth patient. (2) Resetting did not occur (p>0.1) in any of the six patients with PNES. These preliminary results in patients with ES are in agreement with our previous findings from intracranial EEG recordings on resetting of brain dynamics by ES and are expected to constitute the basis for the development of a reliable and supporting tool in the differential diagnosis between ES and PNES. Finally, we believe that these results shed light on the electrophysiology of PNES by showing that occurrence of PNES does not assist patients in overcoming a pathological entrainment of brain dynamics. This article is part of a Supplemental Special Issue entitled The Future of Automated Seizure Detection and Prediction.
Full-text · Article · Dec 2011 · Epilepsy & Behavior
[Show abstract][Hide abstract] ABSTRACT: The average delay in diagnosis of psychogenic non-epileptic seizures (PNES) is more than 7 years. During this period, patients with PNES may suffer from side-effects of unnecessary anti-epileptic drugs (AEDs), not receive appropriate treatment, and lead to the expenditure of millions of dollars in unnecessary health care costs. In this study PNES was investigated in a systematic way in terms of resetting of brain dynamics. We used measures from chaos theory to analyze available long-term scalp electroencephalograms (EEGs) recorded from two PNES patients in order to quantify the probability of resetting the brain’s spatiotemporal synchronization following PNES. We then compared the likelihood of resetting the brain’s synchronization following PNES with other times randomly selected during the recordings. Our results show no significant difference between brain synchronization resetting following PNES versus interictal periods in either patient (p-values of 0.71 and 0.24 respectively). A comparison of these novel results with our prior results of statistically significant (p < 0.05) resetting of brain dynamics following epileptic seizures shows a distinct, possibly defining, difference between PNES and epileptic seizures. This finding could lead to the development of a diagnostic test to distinguish PNES from epileptic seizures.
[Show abstract][Hide abstract] ABSTRACT: The occurrence of epileptic seizures and interictal epileptiform discharges (e.g., spikes, sharp waves) are common during sleep. In this study, we investigated the changes in brain dynamics during sleep and wakefulness states in two patients with focal epilepsy. The electroencephalographic (EEG) activity was recorded from scalp electrodes continuously over several days. Three different measures of dynamics were employed: the measures of Energy, maximum Short-Term Lyapunov exponents (STLmax) and maximum Phase. On the basis of these measures we then estimated the degree of entrainment (synchronization) of dynamics between brain sites. There is a significant (p