Investigating the thermoregulatory role of neurovascular coupling and the anti-epileptogenic and neuroprotective effects of focal cerebral cooling

Acute focal epilepsy is a disease that has proved incredible difficult to treat and often results in very poor outcomes for the patients suffering from the condition. Epilepsy is a disease in which certain parts of the brain become over active this can lead to acute seizures and permanent brain damage; many of the drugs that have been developed don't work over a long time scale. There have been very few therapies that have been shown to work for epilepsy after the primary brain injury has occurred.

A promising new treatment for epilepsy is called focal cooling (FC). FC is a method in which the effected region of the brain is cooled down below body temperature. It is thought that FC works by stopping neuronal activation in the brain. The most appropriate beneficial effects shown by cooling down the brain have been seen in people who have fallen through the ice and have been recovered after tens of minutes or even hours, these patients have been known to make a complete recovery with very careful re-warming procedures, it is thought brain damage is prevented as the cold water puts the brain into a hibernation state which uses very little oxygen. FC applies the same cooling strategy but focused on the area of brain damage. In the case of epilepsy it is to stop the over active region of the brain and bring it down to normal levels therefore preventing any seizures.

Although FC is an incredibly promising method to treat epilepsy with clinical trials already being planned, there has been little research into developing an optimised method for FC treatment in terms of the duration and magnitude of temperature drop in the brain or even in understanding the actual mechanisms by which FC works. For this application we have developed a method for FC treatment in an anaesthetised animal model in which we can measure brain function in an extremely detailed way. The pilot data produced as part of this application shows that FC works as expected by reducing baseline neuronal activation in the brain but also that FC makes oxygen more freely available in the brain to keep it healthy for longer, this second effect has never been shown before. Our pilot experiments also show that focal cortical epilepsy dramatically increases the temperature within the brain by over 2oC and causes a dramatic reduction in the amount of available oxygen. These could be the main reasons for long term brain damage seen in epilepsy patients and explain why FC provides a therapeutic benefit. Using our animal model we will perform experiments to assess the best conditions for FC treatment in the normal animal and then apply these results to acute animal models of epilepsy in our laboratory.

This project will also assess the role of blood flow in keeping the brain at a constant temperature during normal function. Alterations in blood flow in certain diseases or old age, may actually cause increases in brain temperature with the potential to cause brain damage (such as those seen in epilepsy) again this has never been systematically investigated before.

This grant application will develop new and existing technology to assess exactly how one of the most promising treatments for focal cortical epilepsy works. The proposed treatment is called focal cooling (FC); essentially it means cooling down the part of the brain affected by epilepsy to stop or reduce seizures. FC offers the opportunity to develop a successful treatment after the initial cerebral event has occurred and therefore is extremely relevant to human patients.

To investigate how FC works we will employ an acutely anaesthetised rodent model to achieve the following research objectives:

(i) Measure the amount of temperature reduction needed and maximal duration the cerebral cortex and withstand with no side effects and to understand the role played by thermoregulation in neurovascular coupling. We will employ an array of sophisticated imaging and electrophysiological techniques for this research often simultaneously to reduce animal numbers. These include :

2-dimensional optical imaging spectroscopy - To measure hemoglobin changes from the surface of the cortex
Laser Doppler Flowmetry to measure blood flow
Tissue Oxygen measurements
Direct measurement of cerebral cortical temperature changes
Multi-channel electrophysiology to measure neural activity as a function of cortical depth.
Functional magnetic resonance imaging (fMRI) to measure effects of FC from deep brain regions
Thermal imaging to measure the spatial spread of temperature changes produced by physiological stimulation and focal cortical epilepsy
Post mortem histology will be performed after each experiment to asses any tissue damage caused by the FC treatment.

(ii) Apply the optimised FC method to an acute model of focal cortical epilepsy at time points relative to the clinic. The 4-AP model of focal cortical epilepsy has already been developed in Sheffield and a senior post doc is named on the application.

The projects main aim is to understand how focal cooling (FC) works and to optimise its use for the treatment of focal cortical epilepsy. This is a basic science application that has a strong translational component and that is to underpin and refine FC strategies that are currently being proposed for clinical trials with little or no pre-clinical optimisation. The medical, economic, ethical and social impacts of this work will be as follows.

Medical Impact
This research will have two medical impacts the first is that it will assess how useful FC treatment can be using clinically relevant timings for intervention for epilepsy. In this way we will set up criteria that clinical applications will need to meet to translate FC treatment to humans with the best chance of success. The second aspect of research is that the FC may resolve the role played by temperature changes in cerebral pathology. This may extend to many brain disorders in which temperature changes are known to occur such as stroke and traumatic brain injury and lead to new potential treatments. Professor Theodore Schwartz, a named collaborator on this application and a world leading epilepsy neurosurgeon will provide guidance ensure all relevant translational findings of this research are disseminated to the medical community.

Economic Impact
Although this research has no direct commercial component at present the results may lead to new treatment strategies being developed to alleviate the chronic effects of acute epilepsy all of which have significant economic drains on society in terms of caring for these patients. If we can establish a treatment that alleviates all or some of these effects patients will be able to lead productive lives more quickly after the disease has been treated.

Ethical Impact
This research will closely adhere to the principals of the 3R's (reduction, refinement and replacement) for all experimental procedures performed as part of the project. By using multi-modal procedures for the acute animal experiments we will be able to collect a large amount of data from each subject; previously these experiments were carried out in isolation greatly increasing animal numbers used. All ethical permissions for this research are in place.

Social Impact
The research team in Sheffield has a program of outreach to explain the research that we perform and how important it is to society. This project is to develop and refine one of the most promising (and few) treatments for epilepsy that can be performed after the initial brain injury. Many people in society will know the devastating social effects of acute epilepsy not only to the patient but their immediate family and friends. This will be an opportunity to explain to the public the research we do and why it is important. Over the past 12 months researchers in Dr Berwick's team have been actively involved in European researcher's night, to present our findings to the local community in an interactive and fun way. We have also requested £500 per year to further fund these activities including the purchase of interactive 'brain games' and to fund travel costs to local schools.