One in 200 people in the UK have epilepsy, making it the most common serious disease of the brain. Epilepsy is characterised by repeated seizures of cerebral origin, and can be highly disabling. Between 60 and 70 per cent of those who develop epilepsy gain total control of their seizures through anti-epilepsy medication, but for some of those who don't the fallback is surgery. Although not suitable for all, neurosurgery can be highly successful. As neurologist Professor John Duncan comments: "For those people - generally in their teens or 20s - who are having multiple seizures and whose lives are at a standstill as a result, this is life-changing surgery."

According to Professor Duncan, Head of the Department of Clinical and Experimental Neurology at University College London's Institute of Neurology, there is a need for about 1000 epilepsy operations a year in the UK. Surgery is only appropriate for people for whom drugs have failed, and whose seizures come from one part of the brain - and where that part is fairly small and the individual can live without it. This amounts to about 3 per cent of those who develop epilepsy. About 70 per cent of people who have surgery become completely seizure free.

With a new Wellcome programme grant, Professor Duncan and colleagues aim to build on these beginnings, to achieve more precise targeting of surgical intervention, minimising possible disruption to language and memory functions, and maximising impact on epileptic symptoms. Over the next five years, they will use brain imaging and related techniques to identify the parts of the brain involved in epileptic activity, and the parts involved in everyday language and memory functions. A further phase of the research will map nerve fibre tracts, to identify the connections between areas in the brain related to language and memory, and those involved in epileptic activity.

Dissecting brain function

Professor Duncan's department has pioneered the simultaneous use of two common brain analysis tools - electroencephalography (EEG) and functional magnetic resonance imaging (fMRI). EEG, a long-established technique that measures the electrical impulses in the brain, is an important tool in the diagnosis of epilepsy, which is often characterised by particular forms of electrographic activity, both during and between actual seizures. fMRI is a technique that allows brain activity to be monitored noninvasively in different parts of the brain.

Collecting simultaneous data from both EEG and fMRI is technically complex, but is revealing for the first time the regional changes in brain activity directly associated with epileptic activity. This is potentially therapeutically invaluable, says Professor Duncan. "We can differentiate more precisely between different forms of epilepsy, and begin to pinpoint the precise part of the brain that is generating the epileptic activity."

Another major component of Professor Duncan's research is understanding which bits of the brain are crucial in cognitive functioning. Much epilepsy surgery is done on the temporal lobe, and one of the downsides is that while the seizures may be stopped, it may also have an adverse effect on language functions and/or memory.

"The plan here is to use these fMRI techniques to localise which bits of the brain are involved in those functions, and hopefully to show that these are separate from the bits of the brain that give rise to the epilepsy. That way, we can determine where and how the surgery should be done to stand the best chance of stopping the seizures and least chance of causing a cognitive deficit."

Throughout this research Professor Duncan and colleagues will be developing and refining new fMRI techniques, particularly for the temporal lobe regions. These developments, made in collaboration with a number of partners, including the Wellcome Department of Imaging Neuroscience, could have wide clinical significance, enhancing diagnostic data for many neurological conditions.

Neuronal networks

The final component of Professor Duncan's research programme will look at neuronal networks. "It's increasingly felt that the brain isn't a series of modules or independent pieces, but works as a network - both in normal functioning and for epileptic activity. The question is, what is the structural basis of that network - what is the wiring diagram that underlies it?"

He and his colleagues will be using a variation of diffusion tensor imaging known as tractography, which can identify nerve fibre tracts in the brain. As a result, the researchers hope to identify the pathways along which the epileptic activity spreads. "The prediction," says Professor Duncan, "is that if you then make a surgical intervention, which - even if it doesn't take away the entire abnormal area - severed those connections, the network would be disrupted and the seizures would stop. Basically, you don't have to take out the telephone exchange - you can just cut the cables."

Practical applications are always at the forefront of Professor Duncan's mind. He leads a multidisciplinary team of researchers who comprise the Epilepsy Group, a 'symbiotic triad' between the National Society for Epilepsy (NSE), the National Hospital for Neurology and Neurosurgery (NHNN) and the Institute of Neurology. Professor Duncan is Medical Director of the charity, as well as heading up his department at UCL. A number of his colleagues also have joint appointments. "There is no us and them," says Professor Duncan, "and this is fundamental to our success. The NSE resources, in particular their excellent care and research facilities at Chalfont in Buckinghamshire, are available for the application of the research effort. And our work with patients at NHNN means that the research effort is never divorced from clinical priorities."

See also

• Biomedical science previous funding: New insights in the epidemiology and control of Taenia solium taeniasis/cysticercosis

External links

• Epilepsy Imaging Group at the Institute of Neurology, UCL: Research details of Professor John Duncan and his colleagues
• National Society for Epilepsy

Further reading

Rugg-Gunn F J, Eriksson S H, Symms M R, Barker G J, Duncan J S (2001). Diffusion tensor imaging of cryptogenic and acquired partial epilepsies. Brain, 124: 627-636.

Krakow K, Messina D, Lemieux L, Duncan J S, Fish D R (2001). Functional MRI activation of individual interictal epileptiform spikes. Neuroimage, 13: 502-505.

Rugg-Gunn F J, Eriksson S H, Symms M R, Barker G J, Thom M, Harkness W, Duncan J S (2002). Diffusion tensor imaging in refractory epilepsy - localization of focus and histopathological confirmation following resective surgery. Lancet, 359: 1748-51.

Eriksson S H, Symms M R, Rugg-Gunn F J, Boulby P A, Wheeler-Kingshott C A M, Barker G J, Duncan J S, Parker G J M (2002). Exploring white matter tracts in band heterotopia using diffusion tractography. Ann. Neurol. 52:327-334.