Brain implant stops epileptic seizures

Cambridge University have designed a brain implant that can release tiny doses of anti-epilepsy drugs precisely where and only when they’re needed.
04 September 2018

Interview with 

Chris Proctor, University of Cambridge


The wiring of the brain


About one person in every 100 suffers from the brain condition epilepsy, which can lead to fits and seizures. It’s very disruptive to an individual’s life and up to a third of people can’t adequately control their condition with drugs. Now, a team from Cambridge University have designed a brain implant that can release tiny doses of anti-epilepsy drugs precisely where and only when they’re needed. Chris Smith was joined by Chris Proctor who designed the system, who explained what happens when someone has an epileptic seizure.

Chris S - Now first this week, about one person in every 100 suffers from the brain condition epilepsy which can lead to fits and seizures; it's very disruptive for an individual's life, and up to a third of people with it can’t adequately control their condition with drugs. Now a team from Cambridge University have designed a brain implant that can release tiny doses of anti-epilepsy medication precisely where and only when they're needed. Chris Proctor designed the system. Chris, when’s someone's having an epileptic seizure what's actually going on in their brain?

Chris P - So an epileptic seizure is characterised by bursts of activity in the brain, usually some collection of cells, they're sending messages to other cells around them and then this message gets propagated through the other cells throughout the brain. And this can lead to pretty significant symptoms such as loss of consciousness, memory loss, and even tingling sensations in the limbs or convulsions.

Chris S - Now we've said that maybe one in three people can't control this condition with drugs. Obviously two thirds of people can. But for those people who can't, that's where your device might come in handy?

Chris P - Right exactly. So typically for the one in three patients roughly do not respond to traditional medicines, the next best option is to go in the brain and cut out area of the brain that's causing them the problem. Some cases this isn't possible and it's never really desirable. So what we've developed is a solution where you can plant a very tiny device that could detect when a seizure is coming and then intervene to stop that seizure.

Chris S - What does it look like?

Chris P - The implant is quite small, it's roughly the size of two human hairs put together. At the very tip of it, there is an outlet for drugs to come out as well as two tiny sensors to monitor the local activity in the brain.

Chris S - So it's eavesdropping on the neurological activity and what it can tell when there's this sort of signature departure from normal that signals or heralds a seizure is on the way?

Chris P -  Exactly.

Chris S - And how does that then know to dispense agents that will control the seizure?

Chris P - So the implant we've done so far, we ultimately we want to work towards a closed loop system so the device would have some electronics where it would be monitoring in real time what's happening and then know when to intervene. We haven't incorporated that yet. Long term that's where we're going but for the time being we we're actually monitoring the activity ourselves then we could see that seizure was coming and then we could intervene at that point.

Chris S - And how would it expel the drugs from the implant onto the bit of the brain needs them?

Chris P - So the way that this technology works, it's called an ion pumpin or electrophoretic delivery device. So we create a small electric field and then this electric field actually pushes the drug molecules out of the device through some membrane and into the brain. And what's really significant about this is because it's operating in response to an electric field that gives us good control of when drugs are delivered and when they're not. Or how much drug is coming out. And that's equally important. Only the drug molecules are coming out so this does not really impact the local pressure in the environment. So the cells right outside the device are not physically displaced by the drugs coming out and this is rather important for maintaining long term effectiveness of the technology.

Chris S - If you're using an electric field to push the drugs out, does that mean that only certain types of drug molecules that respond to an electric field could be used by the device?

Chris P -Yes so the drug molecules have to have some sort of ionic form that means they have to carry some charge but it turns out a lot of drugs actually do carry some charge including inhibitory neurotransmitters that were used in this study which are native to the body.

Chris S - So could you take a cocktail of agents? Because we know that everyone is different so everyone's presentation disease or response to drugs might be different. Could you mix up a cocktail unique to a person and squeeze that out of the implant in order to achieve optimum control of an individual's problem?

Chris P - You absolutely could so long as there are charge molecules. I mean this is something we're pursuing now kind of working towards optimising the dose of one or multiple drugs to better effect a seizure or some other disorder.

Chris S - How do you actually get the implant in in the first place and how do you know where to put it?

Chris P - So in this study we've done so far, we were actually having another implant in place to inject some chemicals to cause a seizure. So we knew we created ourselves the seizure so we knew where to put our device. But in practice today it's actually quite standard to map brain activity using a series of electrodes either on the surface of the brain or going into the brain. And from that you can determine where the seizure is emanating from so that would be where you would put the device.

Chris S - If it's only the size of a couple of human hairs laid side by side that's incredibly small, can it hold much drug? Is that enough?

Chris P - So what we found in this study is actually surprisingly a very small amount of drug goes a long way. So less than 1 percent of the loaded capacity of the drug was able to completely prevent what would have been otherwise very catastrophic seizure-like activity in animals.

Chris S - And lastly the brain isn't the only electrically active organ in the body. There are things like the heart as well where drugs squirted onto specific areas might make a very big difference to a person. Could you deploy this somewhere else as well?

Chris P - Yeah there's tremendous potential to use this as a platform to deliver drugs throughout the body - the heart, the peripheral nervous system. I think there's a lot of exciting applications and we're really looking forward to applying this more widely.


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