Homeostasis of Brain Dynamics in Epilepsy: A Feedback Control Systems Perspective of Seizures

In an effort to understand basic functional mechanisms that can produce epileptic seizures, some key features are introduced in coupled lumped-parameter neural population models that produce “seizure”-like events and dynamics similar to the ones during the route of the epileptic brain towards seizures. In these models, modified from existing ones in the literature, internal feedback mechanisms are incorporated to maintain the normal low level of synchronous behavior in the presence of coupling variations. While the internal feedback is developed using basic feedback systems principles, it is also functionally equivalent to actual neurophysiological mechanisms such as homeostasis that act to maintain normal activity in neural systems that are subject to extrinsic and intrinsic perturbations. Here it is hypothesized that a plausible cause of seizures is a pathology in the internal feedback action; normal internal feedback quickly regulates an abnormally high coupling between the neural populations, whereas pathological internal feedback can lead to “seizure”-like high amplitude oscillations. Several external seizure-control paradigms, that act to achieve the operational objective of maintaining normal levels of synchronous behavior, are also developed and tested in this paper. In particular, closed-loop “modulating” control with predefined stimuli, and closed-loop feedback decoupling control are considered. Among these, feedback decoupling control is the consistently successful and robust seizure-control strategy. The proposed model and remedies are consistent with a variety of recent observations in the human and animal epileptic brain, and with theories from nonlinear systems, adaptive systems, optimization, and neurophysiology. The results from the analysis of these models have two key implications, namely, developing a basic theory for epilepsy and other brain disorders, and the development of a robust seizure-control device through electrical stimulation and/or drug intervention modalities

Terutroban versus aspirin in patients with cerebral ischaemic events (PERFORM): a randomised, double-blind, parallel-group trial

Background: Patients with ischaemic stroke or transient ischaemic attack (TIA) are at high risk of recurrent stroke or other cardiovascular events. We compared the selective thromboxane-prostaglandin receptor antagonist terutroban with aspirin in the prevention of cerebral and cardiovascular ischaemic events in patients with a recent non-cardioembolic cerebral ischaemic event. <p/>Methods: This randomised, double-blind, parallel-group trial was undertaken in 802 centres in 46 countries. Patients who had an ischaemic stroke in the previous 3 months or a TIA in the previous 8 days were randomly allocated with a central interactive response system to 30 mg per day terutroban or 100 mg per day aspirin. Patients and investigators were masked to treatment allocation. The primary efficacy endpoint was a composite of fatal or non-fatal ischaemic stroke, fatal or non-fatal myocardial infarction, or other vascular death (excluding haemorrhagic death). We planned a sequential statistical analysis of non-inferiority (margin 1·05) followed by analysis of superiority. Analysis was by intention to treat. The study was stopped prematurely for futility on the basis of the recommendation of the Data Monitoring Committee. This study is registered, number ISRCTN66157730. <p/>Findings: 9562 patients were assigned to terutroban (9556 analysed) and 9558 to aspirin (9544 analysed); mean follow-up was 28·3 months (SD 7·7). The primary endpoint occurred in 1091 (11%) patients receiving terutroban and 1062 (11%) receiving aspirin (hazard ratio [HR] 1·02, 95% CI 0·94–1·12). There was no evidence of a difference between terutroban and aspirin for the secondary or tertiary endpoints. We recorded some increase in minor bleedings with terutroban compared with aspirin (1147 [12%] vs 1045 [11%]; HR 1·11, 95% CI 1·02–1·21), but no significant differences in other safety endpoints. <p/>Interpretation: The trial did not meet the predefined criteria for non-inferiority, but showed similar rates of the primary endpoint with terutroban and aspirin, without safety advantages for terutroban. In a worldwide perspective, aspirin remains the gold standard antiplatelet drug for secondary stroke prevention in view of its efficacy, tolerance, and cost

Rationale and design of a randomized, double-blind, parallel-group study of terutroban 30 mg/day versus aspirin 100 mg/day in stroke patients: the prevention of cerebrovascular and cardiovascular events of ischemic origin with terutroban in patients with a history of ischemic stroke or transient ischemic attack (PERFORM) study.

BACKGROUND: Ischemic stroke is the leading cause of mortality worldwide and a major contributor to neurological disability and dementia. Terutroban is a specific TP receptor antagonist with antithrombotic, antivasoconstrictive, and antiatherosclerotic properties, which may be of interest for the secondary prevention of ischemic stroke. This article describes the rationale and design of the Prevention of cerebrovascular and cardiovascular Events of ischemic origin with teRutroban in patients with a history oF ischemic strOke or tRansient ischeMic Attack (PERFORM) Study, which aims to demonstrate the superiority of the efficacy of terutroban versus aspirin in secondary prevention of cerebrovascular and cardiovascular events. METHODS AND RESULTS: The PERFORM Study is a multicenter, randomized, double-blind, parallel-group study being carried out in 802 centers in 46 countries. The study population includes patients aged > or =55 years, having suffered an ischemic stroke (< or =3 months) or a transient ischemic attack (< or =8 days). Participants are randomly allocated to terutroban (30 mg/day) or aspirin (100 mg/day). The primary efficacy endpoint is a composite of ischemic stroke (fatal or nonfatal), myocardial infarction (fatal or nonfatal), or other vascular death (excluding hemorrhagic death of any origin). Safety is being evaluated by assessing hemorrhagic events. Follow-up is expected to last for 2-4 years. Assuming a relative risk reduction of 13%, the expected number of primary events is 2,340. To obtain statistical power of 90%, this requires inclusion of at least 18,000 patients in this event-driven trial. The first patient was randomized in February 2006. CONCLUSIONS: The PERFORM Study will explore the benefits and safety of terutroban in secondary cardiovascular prevention after a cerebral ischemic event.Journal ArticleMulticenter StudyRandomized Controlled TrialResearch Support, Non-U.S. Gov'tinfo:eu-repo/semantics/publishe

Rationale and design of a randomized, double-blind, parallel-group study of terutroban 30 mg/day versus aspirin 100 mg/day in stroke patients: the prevention of cerebrovascular and cardiovascular events of ischemic origin with terutroban in patients with a history of ischemic stroke or transient ischemic attack (PERFORM) study.

BACKGROUND: Ischemic stroke is the leading cause of mortality worldwide and a major contributor to neurological disability and dementia. Terutroban is a specific TP receptor antagonist with antithrombotic, antivasoconstrictive, and antiatherosclerotic properties, which may be of interest for the secondary prevention of ischemic stroke. This article describes the rationale and design of the Prevention of cerebrovascular and cardiovascular Events of ischemic origin with teRutroban in patients with a history oF ischemic strOke or tRansient ischeMic Attack (PERFORM) Study, which aims to demonstrate the superiority of the efficacy of terutroban versus aspirin in secondary prevention of cerebrovascular and cardiovascular events. METHODS AND RESULTS: The PERFORM Study is a multicenter, randomized, double-blind, parallel-group study being carried out in 802 centers in 46 countries. The study population includes patients aged > or =55 years, having suffered an ischemic stroke (< or =3 months) or a transient ischemic attack (< or =8 days). Participants are randomly allocated to terutroban (30 mg/day) or aspirin (100 mg/day). The primary efficacy endpoint is a composite of ischemic stroke (fatal or nonfatal), myocardial infarction (fatal or nonfatal), or other vascular death (excluding hemorrhagic death of any origin). Safety is being evaluated by assessing hemorrhagic events. Follow-up is expected to last for 2-4 years. Assuming a relative risk reduction of 13%, the expected number of primary events is 2,340. To obtain statistical power of 90%, this requires inclusion of at least 18,000 patients in this event-driven trial. The first patient was randomized in February 2006. CONCLUSIONS: The PERFORM Study will explore the benefits and safety of terutroban in secondary cardiovascular prevention after a cerebral ischemic event