· Neurological device set for trials this summer
· Implant could be used to treat other disorders
Tuesday June 27, 2006
Guardian
Scientists in America have developed a treatment for epilepsy which they say could help millions of people with the condition. Researchers at the Massachusetts Institute of Technology hope to try out the neurological pacemaker, which detects and treats seizures before they happen, this summer."Unlike so many other illnesses where we can easily measure what's going on, epilepsy has been difficult to understand," said Professor John Guttag of MIT, who is supervising the project. "It's one of the main reasons there has been so much of a stigma attached to the condition - for centuries epileptics were even thought to be possessed by the devil."
The new procedure is based around an existing treatment known as vagus nerve stimulation (VNS). A small electrical device is planted in the body which sends regular electrical pulses to the brain, usually one every five minutes throughout the day. Experts at MIT say they have developed a method of analysing the brain's activity which can be used alongside VNS to prevent seizures from occurring.
By using electrodes attached to a cap, the system can monitor neurological activity and determine when an episode is likely. A message is then sent to the VNS implant, which sends a specific shock to prevent the incident, rather than the scatter-gun of electric shocks currently used.
Researchers say this will dramatically reduce the number of pulses sent to the brain and more effectively control epilepsy.
MIT researcher Ari Shoeb, who developed the system, and Steven Schacter, an expert in VNS, say they are preparing to test the procedure on a handful of patients over the next few months. Tests using existing data have encouraged them to think that success could lead to much wider adoption of VNS as a treatment for neurological problems.
Around 456,000 people have epilepsy in Britain, a third of whom cannot be treated with medication. Even those who can use medical controls are often plagued with unpleasant side-effects. Nerve stimulation has proved a successful alternative, with around two-thirds of all patients experiencing significant improvements.
Although VNS therapies involve a surgical procedure the success rates are high, and non-invasive diagnosis could not only revolutionise the way that epilepsy is treated, but also be applicable to a number of other neurological disorders.
There are some similarities to deep brain stimulation techniques which are being developed to help stop the symptoms of Parkinson's disease or severe depression, but these involve placing electrodes directly into the brain.
Experts say that if the new analytical technique is successful, it could provide similar kinds of relief without being so surgically invasive.
"All research has to be welcomed because we're still trying to understand exactly what is happening in epileptic seizures," said Margaret Thomas, a spokeswoman for the National Society for Epilepsy. "Vagus nerve stimulation works for some people but not everyone - but we are looking forward to the results of any clinical trials."
The team behind the new system say they are still some way from reaching the public, and each device will need to be tailored to the individual patient. "At the moment we have developed a diagnostic tool," said Professor Guttag. "But there will be some serious development work to make it small and portable, not in the sense of needing a scientific breakthrough but lots of hard engineering."
http://www.guardian.co.uk/medicine/story/0,,1806691,00.ht
 Thursday, July 06, 2006 Catching
Seizures Before They Occur
A wearable
detection device could help millions of people who suffer from epilepsy.
By Duncan Graham-Rowe
Researchers at MIT and Harvard are preparing to carry out trials of a new device for treating epilepsy. If successful, it would be the first such device to automatically detect and treat seizures, says John Guttag, at MIT's Computer Science and Artificial Intelligence Lab, who developed it with colleague Ali Shoeb and Steven Schachter, a neurologist at Harvard Medical School, in Boston. Currently, more than two million people in the United States alone have epilepsy. And globally it affects one in every 100 people. While about half of them are able to treat the condition with drug therapies, many others fight a constant battle to find the right drugs to target their condition. And, for many sufferers, such as those whose epilepsy is caused by trauma to the brain, drugs are not an option. Guttag is working on a technological alternative that involves implanting a pacemaker-like device in the patient's chest. Connected to the device is an electrode that wraps around the vagus nerve, a large nerve that runs down from the brainstem through the neck and into the abdomen. This vagal nerve stimulator (VNS) has two modes, says Guttag. One stimulates the nerve electrically at regular intervals. "There is some evidence that this periodic stimulation has a long-term prophylactic effect," he says. But this is hit or miss. The other "on-demand" mode, which uses more powerful electrical stimulations, can be activated by the patient when a seizure occurs to try to stop it. Although precisely why this works is unknown, there's plenty of evidence that VNS can actually stop seizures, says Guttag. But there's a catch. To activate the on-demand mode, patients must swipe a magnetic wrist strap across their chest whenever they feel a seizure coming on, explains Harvard's Schachter. Hence, a patient must be able to sense the early signs of a seizure in enough time to do anything about it. "In my experiences more than half cannot perceive the onset of the seizures," says Schachter. And of those who do manage to use the magnet, only one in four cases results in a reduction of the seizure's severity, he says. This may be due to a latency effect: any delay could be less effective at reducing the symptoms. "Part of the problem with VNS is that it's not a closed loop system," says Steven Rothman, a neurologist at Washington University in St. Louis, MO, meaning there's no feedback to the device. He points out that it would be more effective if the system itself, not the patient, could detect the seizure. A new version of Guttag's VNS device, which will be tested on between 10 and 20 patients over the next few months, attempts to solve this problem by providing the device with feedback from the patient. The patient's brain activity will be monitored using an electroencephalogram (EEG) that is continuously analyzed by a detection program. When a seizure is detected, the device will activate an electromagnet hung over the patient's chest, which, in turn, will activate the implanted VNS device. Initially, the EEG electrodes will be worn as part of a device that looks like a swimming cap, says Guttag. It wouldn't have to be worn all the time, but could be used, for example, when driving. And the long-term goal is a much less conspicuous object ("We could easily put it under a hair piece"). Eventually, the electrodes could be placed permanently under the scalp, he says. Similarly, the electromagnetic triggering mechanism would be integrated within the implanted VNS device. The mechanics of this proof-of-principle set-up are still crude, says Schachter, but the all-important algorithms are reliable. In fact, the goal is a detection program good enough to sense a seizure much earlier than a patient could. If so, such a device would not only dramatically reduce the severity of seizures, but also might also prevent them. Another device for detecting seizures, the Response Neurostimulator, developed by NeuroPace in Mountain View, CA, is also under development and currently undergoing clinical trials. And it also involves trying to detect seizures at an early stage. However, instead of stimulating the vagus nerve, it electrically stimulates the brain directly via electrodes implanted on the surface of or inside the brain. In theory, NeuroPace's device should have an easier job of detecting the seizure, says Brian Litt, a neurologist and bioengineer at the Hospital of the University of Pennsylvania, in Philadelphia, because such detection electrodes can be placed directly on the brain. In contrast, scalp electrodes tend to pick up much noisier signals, he says. As far as Guttag is concerned, though, VNS has a clear advantage: "It's less invasive, because we're not actually putting anything in the brain." Indeed, a VNS device that could operate automatically would be welcomed by patients, says Litt. If successful, it could do for epilepsy what pacemakers and implantable defibrillators have done for heart conditions, he says. "At the moment, it's the equivalent of saying ‘when you feel a potentially fatal heart rhythm coming along hit yourself in the chest'." Copyright Technology Review 2006.
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