Project 463550

Patients with significant brain insults (ex. hemorrhage, infection) are admitted to the intensive care unit for close monitoring. As such, electrodes are often glued to their head for continuous surveillance of the brain's electrical activity as acute brain injuries frequently generate abnormal electrical discharges. The most known one is called a seizure (or 'ictus', analogous to a thunderstorm) which is a sustained excessive discharge lasting a few minutes and associated with clinical manifestations (ex. convulsions). Convulsive seizures can lead to brain hypoxia, permanent brain damage or even death if not rapidly detected and terminated with antiseizure medications. At the other end of the spectrum are isolated interictal epileptiform discharges (analogous to lightning bolts, also known as "spikes"). These spikes are brief excessive discharges identifiable on the EEG but not strong enough to generate symptoms. Current practice is not to treat them aggressively. Between spikes and seizures, a wide range of abnormal discharges have been described based on their appearance on the EEG, whose significance and management are still very much unclear such as recurring discharges with a period of a second or more, discharges triggered by stimulation, and seizures without clinical manifestations. These commonly encountered EEG patterns, situated on what is called the interictal-ictal continuum, remain a major challenge in daily clinical practice since nobody knows whether treatment should be performed. This project will investigate the brain in this context combining EEG with functional near infrared spectroscopy, a low energy light-based technique which detects alterations in cortical cerebral blood volume and blood oxygenation. We aim to determine the significance of these abnormal discharges (i.e. whether they are harmful to the brain) and to make progress towards clinical monitoring of metabolic stress associated with the discharges in critically ill patients.