Posts tagged epilepsy
Articles and news from the latest research reports.
Yale researchers studying epileptic seizures have shed new light on the neurological origins of consciousness.
When epileptics lose consciousness during a variety of types of seizures, the signals converge on the same brain structures, but through different pathways, says Dr. Hal Blumenfeld, professor of neurology, neurobiology, and neurosurgery.
“Understanding of these mechanisms could lead to improved treatment strategies to prevent impairment of consciousness and improve the quality of life of people with epilepsy,” he said.
Blumenfeld’s research is described in the current issue of the journal Lancet Neurology.
(Image: The fMRI images are different viewpoints of the brain of a child experiencing an epileptic seizure. Areas in yellow and orange represent increased brain activity compared to its normal state, while areas in blue show decreased activity. These are the areas of the brain needed for normal consciousness.)
Western researchers explore secret origin of déjà vu
August 10, 2012
Most people have been in a situation that suddenly feels strangely familiar, while also realizing that they have never been in that specific place before. These experiences are called ‘déjà vu’ and the phenomenon has inspired countless books, songs and movies.
What is remarkable about déjà vu, says Western University graduate student Chris Martin, is that the impression of familiarity is accompanied by a sense that the current environment or situation should in fact feel new. But how can it be that a scene or an experience evokes a sense of familiarity but at the same time a feeling that this familiarity is wrong?
Despite the curiosity and excitement about déjà vu in popular culture, these subjective experiences remain poorly understood in scientific terms. Studying déjà vu has proven difficult due to the fleeting nature of these obscure occurrences, and due to the lack of experimental procedures to elicit them in the psychological laboratory.
In an article published online by Neuropsychologia, “Déjà Vu in Unilateral Temporal-Lobe Epilepsy is Associated with Selective Familiarity Impairments on Experimental Tasks of Recognition Memory,” Martin and psychology professor Stefan Köhler were able to shed light on this fascinating phenomenon by examining a rare group of neurological patients that experience déjà vu as an early sign of advancing seizures.
Due to lasting underlying brain pathology, most patients with temporal lobe epilepsy exhibit subtle impairments in memory even at times when no seizures are present. Köhler and his team built on this link by seeking behavioural markers of déjà vu on specific memory tasks that were designed to probe feelings of familiarity. The researchers discovered a pattern of performance that clearly distinguished patients with déjà vu from those without.
Specifically, familiarity was selectively impaired only in individuals with déjà vu in their seizure profile. In an experiment that placed different types of memories in conflict, patients with déjà vu were still able to counteract inappropriate feelings of familiarity with their ability to recollect pertinent information about previous actual events.
These findings, say Köhler and Martin, open a new window towards understanding the psychological and neural mechanisms that give rise to fleeting, subjective feelings of déjà vu. Köhler says they remind us that even when lasting for just a split second, memory experiences reflect the interplay of many different, sometimes competing processes. On another level, these findings are also of clinical relevance in the surgical treatment of temporal lobe epilepsy.
Source: University of Western Ontario
Electrical Brain Stimulation Curbs Epileptic Seizures in Rats
THURSDAY, Aug. 9 (HealthDay News) — Researchers report that they have created a device able to short-circuit epileptic seizures in rats.
Similar in design to an implantable defibrillator, the device is placed in the brain and reacts only when a seizure starts to occur, essentially aborting the seizure’s electrical activity.
The self-adjusting device electrically stimulates the brain at the beginning of a short but frequent type of seizure in rats, and then automatically shuts itself off. The research was published in the Aug. 10 issue of the journal Science.
"It works like a ping-pong game," explained study author Dr. Gyorgy Buzsaki, a professor of neural science at New York University. "Every time a ball is coming your way, you apply an interfering pattern to whack it away."
Epilepsy is a brain disorder in which a person has repeated seizures over time. It affects nearly 3 million Americans, according to the Epilepsy Foundation, making it the third most common neurological disorder in the United States, after Alzheimer’s and stroke.
People with epilepsy can suffer from two different kinds of seizures: petit mal seizures, which last for just a few seconds but can occur frequently, and grand mal seizures, which are rare but involve violent muscle contractions and a loss of consciousness.
Seizures are episodes of disturbed brain activity that cause changes in attention or behavior. Brain cells keep firing instead of acting in an organized way. The malfunctioning electrical system of the brain causes surges of energy that can cause unconsciousness and muscle contractions.
The researchers tested the new device against petit mal seizures in rats because this type of seizure occurs hundreds of times a day. The sheer volume of the seizures allowed the scientists to effectively test the system they designed. People with petit mal seizures are typically treated effectively with drugs, so the device would not be used to treat that type of seizure.
In what Buzsaki describes as a simple, closed-loop system, the firing of brain neurons creates a spike in neurological activity that is followed by a wave and detected by the device, which fires back only when necessary. The system, called transcranial electrical stimulation, leaves other aspects of brain function unaffected. “The system doesn’t prevent seizures, it just treats them right away,” said Buzsaki. The stimulation reduced the length of a seizure by about 60 percent.
In humans, two plates about the size of a pocket watch could be placed in the skull in a position designed to target the affected area of the brain. The electrodes would be powered by ultralight electrical circuits implanted in the skull, Buzsaki explained.
The goal is to apply the system that worked in rats to people with complex partial seizures — epileptic seizures that affect both sides of the brain and cause a loss of consciousness, Buzsaki said. Although the device worked in rats, the results may not translate to humans.
This type of seizure also can occur with head injuries, brain infection and stroke. The cause is typically unknown.
In 20 percent to 40 percent of people who have complex partial seizures, drugs are ineffective and there are no remedies, Buzsaki said. “It’s not clear what kind of stimulation to deliver and where exactly in the brain the stimulation should go,” he explained.
Dr. Orrin Devinsky, director of the epilepsy program at New York University, said the research has enormous potential for treating epilepsy and other neurological problems. “What’s unique about this technique is that it’s a sophisticated way to identify the rhythmicity of the seizure itself and interrupt the cycle with precision,” he said. “Existing [deep brain stimulation] devices don’t finesse the timing this way.”
Devinsky, who was not associated with the study, said the research could potentially be applicable to people with tremors, Parkinson’s disease and even those with serious depression and other psychological disorders.
Source: HealthDay
In the journal Experimental Neurology, the scientists report the beneficial effects of so-called astrocytes, a certain type of glial cells. They get their name from the Greek word for glue, as it was long thought that these cells simply hold the nerve cells together and provided them with nutrients. In the case of epilepsy, the prevalent opinion was that their reaction to a seizure would actually damage the brain. The researchers from Freiburg disagree. In fact, they say, astrocytes help to reduce long-term damage brought upon by epileptic fits.
The team discovered the positive effects of astrocytes in mice, in which epileptic states can be selectively triggered. If the scientists injected mice with a specific protein to activate the astrocytes prior to an epilepsy-inducing insult, fewer nerve cells died in the wake of the seizure. Other pathological changes that would usually occur in the brain were likewise significantly reduced. The astrocytes’ protective effect lasted for many days after their activation. When the researchers measured the rodents’ brain activity, they likewise found fewer signs that are typical for a brain suffering from epilepsy. However, the authors report that the astrocytes had to be already activated before seizures were elicited. Activating them afterwards, on the other hand, did not lead to a protective effect.
Further studies will have to demonstrate that astrocytes have this protective influence all over the brain. According to Haas, who is also a member of Freiburg’s new cluster of excellence BrainLinks-BrainTools, their findings suggest that a timely activation of astrocytes could offer an effective protection from long-term damage to the brain.
The World’s Most Famous Brain
In the summer of 1953, Henry Gustav Molaison (1926-2008) underwent brain surgery to contain epileptic seizures that had become critically debilitating. The intervention brought some relief from convulsions, but these positive results were overshadowed by an astonishing and indelible side effect. Soon after the operation, it became apparent that he could no longer recognize hospital staff, he did not remember the way home, he did not remember newspaper articles he had just read, nor the crossword puzzles he had solved; otherwise, he was completely normal. Since the time of the surgery, more than five decades of scrupulous neuropsychological research examined the nature of patient H.M.’s amnesia which proved to be both persistent and remarkably selective.
The goal of our project is to provide a window into the brain of the man who helped establish the scientific study of memory and unfailingly forgot the enormously generous contribution he made to medical research.
Protein-Based Coating Could Help Rehabilitate Long-Term Brain Function
Tuesday, July 31, 2012
TAU researchers develop bioactive coating to “camouflage” neutral electrodes
Brain-computer interfaces are at the cutting edge for treatment of neurological and psychological disorder, including Parkinson’s, epilepsy, and depression. Among the most promising advance is deep brain stimulation (DBS) — a method in which a silicon chip implanted under the skin ejects high frequency currents that are transferred to the brain through implanted electrodes that transmit and receive the signals. These technologies require a seamless interaction between the brain and the hardware.
But there’s a catch. Identified as foreign bodies by the immune system, the brain attacks the electrodes and forms a barrier to the brain tissue, making it impossible for the electrodes to communicate with brain activity. So while the initial implantation can diminish symptoms, after a few short years or even months, the efficacy of this therapy begins to wane.
Now Aryeh Taub of Tel Aviv University's School of Psychological Sciences, along with Prof. Matti Mintz, Roni Hogri and Ari Magal of TAU’s School of Psychological Sciences and Prof. Yosi Shacham-Diamand of TAU’s School of Electrical Engineering, has developed a bioactive coating which not only “camouflages” the electrodes in the brain tissue, but actively suppresses the brain’s immune response. By using a protein called an “interleukin (IL)-1 receptor antagonist” to coat the electrodes, the multi-disciplinary team of researchers has found a potential resolution to turn a method for short-term relief into a long-term solution. This development was reported in the Journal of Biomedical Materials Research.
Limiting the immune response
To overcome the creation of the barrier between the tissue and the electrode, the researchers sought to develop a method for placing the electrode in the brain tissue while hiding the electrode from the brain’s immune defenses. Previous research groups have coated the electrodes with various proteins, says Taub, but the TAU team decided to take a different approach by using a protein that is active within the brain itself, thereby suppressing the immune reaction against the electrodes.
In the brain, the IL-1 receptor antagonist is crucial for maintaining physical stability by localizing brain damage, Taub explains. For example, if a person is hit on the head, this protein works to create scarring in specific areas instead of allowing global brain scarring. In other words, it stops the immune system from overreacting. The team’s coating, the first to be developed from this particular protein, not only integrates the electrodes into the brain tissue, but allows them to contribute to normal brain functioning.
In pre-clinical studies with animal models, the researchers found that their coated electrodes perform better than both non-coated and “naïve protein”-coated electrodes that had previously been examined. Measuring the number of damaged cells at the site of implantation, researchers found no apparent difference between the site of electrode implantation and healthy brain tissue elsewhere, Taub says. In addition, evidence suggests that the coated electrodes will be able to function for long periods of time, providing a more stable and long-term treatment option.
Restoring brain function
Approximately 30,000 people worldwide are currently using deep brain stimulation (DBS) to treat neurological or psychological conditions. And DBS is only the beginning. Taub believes that, in the future, an interface with the ability to restore behavioral or motor function lost due to tissue damage is achievable — especially with the help of their new electrode coating.
"We duplicate the function of brain tissue onto a silicon chip and transfer it back to the brain," Taub says, explaining that the electrodes will pick up brain waves and transfer these directly to the chip. "The chip then does the computation that would have been done in the damaged tissue, and feeds the information back into the brain — prompting functions that would have otherwise gotten lost."
Source: Tel Aviv University
New epilepsy gene identified; possible new treatment option
ScienceDaily (July 23, 2012) — New research conducted by neuroscientists from the Royal College of Surgeons in Ireland (RCSI) published in Nature Medicine has identified a new gene involved in epilepsy and could potentially provide a new treatment option for patients with epilepsy.
The research focussed on a new class of gene called a ‘microRNA’ which controls protein production inside cells. The research looked in detail at one particular microRNA called ‘microRNA-134’ and found that levels of microRNA-134 are much higher in the part of the brain that causes seizures in patients with epilepsy.
By using a new type of drug-like molecule called an antagomir which locks onto the ‘microRNA-134’ and removes it from the brain cell, the researchers found they could prevent epileptic seizures from occurring.
Professor David Henshall, Department of Physiology & Medical Physics, RCSI and senior author on the paper said ‘We have been looking to find what goes wrong inside brain cells to trigger epilepsy. Our research has discovered a completely new gene linked to epilepsy and it shows how we can target this gene using drug-like molecules to reduce the brain’s susceptibility to seizures and the frequency in which they occur.”
Dr Eva Jimenez-Mateos, Department of Physiology & Medical Physics, RCSI and first author on the paper said “Our research found that the antagomir drug protects the brain cells from toxic effects of prolonged seizures and the effects of the treatment can last up to one month.”
Epilepsy affects 37,000 in Ireland alone. For every two out of three people with epilepsy their seizures are controlled by medication, but one in three patients continues to have seizures despite being prescribed medication. This study could potentially offer new treatment methods for patients.
The research was supported by a grant from Science Foundation Ireland (SFI). Researchers in the Department of Physiology & Medical Physics and Molecular & Cellular Therapeutics, RCSI, clinicians at Beaumont Hospital and experts in brain structure from the Cajal Institute in Madrid were involved in the study.
Source: Science Daily
Epilepsy drugs increase risk of fractures and falls
June 28, 2012
(Medical Xpress) — New research has shed light on the high risk of fractures, falls, and osteoporosis among epilepsy patients using antiepileptic drugs with most patients unaware of the risks associated with taking the drugs.
The study led by the University of Melbourne and published in the prestigious Neurology journal, found that people taking antiepileptic drugs are up to four times more likely to suffer spine, collarbone and ankle fractures and are more likely to have been diagnosed with osteoporosis.
The study also revealed that these patients are more than four times as likely as non-users of antiepileptic drugs to have been diagnosed with osteoporosis.
In addition, treatment affected balance with results showing almost double the falls rate in female patients taking the medication compared with non-users.
Chief Investigator, Prof John Wark from the University of Melbourne’s Department of Medicine at the Royal Melbourne Hospital said this research revealed new information critical to understanding the higher risk for fractures and falls in epilepsy patients taking antiepileptic medication.
“We believe patients need to be offered better information to help them to avoid these risks and prevent injury,” he said.
More than 70 percent of epilepsy patients who participated in the study were unaware of the increased risk of fractures, decreased bone mineral density and falls associated with taking antiepileptic medications.
“No published studies have explored epilepsy patients’ awareness of the effects of AEDs on bone health, fracture risk and falls. This study indicates that awareness of these issues is poor, despite our study population attending specialist epilepsy clinics at a centre with a major interest in this area,” said Prof Wark.
“Most patients indicated they would like to be better informed about these issues, suggesting that more effective education strategies are warranted and would be well-received.”
“Epilepsy patients should be assessed regularly for their history of falls and fractures for appropriate management strategies to be offered.”
The study compared 150 drug users with 506 non-users. All drug users were epilepsy outpatients at the Royal Melbourne Hospital, over 15 years old and had been taking AEDs for a minimum of three months.
Provided by University of Melbourne
Source: medicalxpress.com
New invasive imaging technique to monitor brain function
June 26, 2012
A new video article in JoVE, the Journal of Visualized Experiments, describes a novel procedure to monitor brain function and aid in functional mapping of patients with diseases such as epilepsy. This procedure illustrates the use of pre-placed electrodes for cortical mapping in the brains of patients who are undergoing surgery to minimize the frequency of seizures. This technique, while invasive, provides real-time analysis of brain function at a much higher resolution than current technologies.
This image shows the implanted electrodes as they are mapped on the brain. Credit: Journal of Visualized Experiments
Typically, functional magnetic resonance imaging (fMRI) and electroencephalography (EEG) are used in neuroimaging studies but these techniques suffer from low temporal and spatial resolution. By using electrodes implanted in the brain of an epileptic patient already undergoing treatment, scientists can now image the brain with a much higher spatial resolution, lower signal interference, and a higher temporal resolution than fMRI or EEG.
The leading author of the study, Dr. Gerwin Schalk, from the New York State Department of Health and Albany Medical College, states, “Essentially, we have created a new imaging technique. Our procedure is innovative because it is prospective, meaning, it can image brain function as it occurs. Further, it does not require an expert to derive meaningful information concerning brain function.” He also notes that it was crucial for this procedure to be demonstrated in a video format. “The procedure is a very visual process. The ancillary information such as the spatial relationships of different components, the set-up of the hospital room, and the set-up of the equipment itself cannot be represented in a typical print article. The video capacities of JoVE were an excellent vehicle to demonstrate both the general set-up and the specific implementation of the mapping system.”
By relying on an epileptic patient’s neural implants, scientists gain an unprecedented insight into the brain’s function. Dr. Schalk’s procedure provides a technological advancement that can be applied in many ways, including stroke patient monitoring and rehabilitation, signal mapping and transduction for movement of prosthetic limbs, and enhancement of communication in individuals with paralysis of the vocal musculature. The JoVE video article provides a comprehensive demonstration of the new technique, from mapping the electrical implants to interpreting the tests in real time. JoVE editor Dr. Claire Standen emphasizes, “The new imaging technique demonstrated in this article is very important. There is a definite need for better, more accurate, imaging to monitor brain function. This technique can be applied to a wide range of clinical areas within the Neuroscience field.” The article can be found here: Recording Human Electrocorticographic (ECoG) Signals for Neuroscientific Research and Real-time Functional Cortical Mapping
Provided by The Journal of Visualized Experiments
Source: medicalxpress.com
Study reports seizure-freedom in 68 percent of juvenile myoclonic epilepsy patients
June 6, 2012
A 25-year follow-up study reveals that 68% of patients with juvenile myoclonic epilepsy (JME) became seizure-free, with nearly 30% no longer needing antiepileptic drug (AED) treatment. Findings published today in Epilepsia, a journal of the International League Against Epilepsy (ILAE), report that the occurrence of generalized tonic-clonic seizures preceded by bilateral myoclonic seizures, and AED polytherapy significantly predicted poor long-term seizure outcome.
Patients with JME experience “jerking” of the arms, shoulders, and sometimes the legs. Previous evidence suggests that JME is a common type of epilepsy (in up to 11% of people with epilepsy), occurring more frequently in females than in males, and with onset typically in adolescence.. There is still much debate among experts over the long-term outcome of JME, and about which factors predict seizure outcome.
To further investigate JME outcomes and predictive factors, Dr. Felix Schneider and colleagues from the Epilepsy Center at the University of Greifswald in Germany studied data from 12 male and 19 female patients with JME. All participants had a minimum of 25 years follow-up which included review of medical records, and telephone or in-person interviews.
Sixty-eight percent of the 31 JME patients became free of seizures, and 28% discontinued AED treatment due to seizure-freedom. Significant predictors of poor long-term seizure outcome included: occurrence of generalized tonic-clonic seizures (GTCS - formerly known as grand mal seizures) that affect the entire brain and which are preceded by bilateral myoclonic seizures (abnormal movements on both sides of the body and a regimen of AED polytherapy.
Researchers also determined that remission of GTCS using AED therapy significantly increased the possibility of complete seizure-freedom. However, once AED therapy is discontinued, the occurrence of photoparoxysmal responses (brain discharges in response to brief flashes of light) significantly predicted an increased risk of seizure recurrence.
"Our findings confirm the feasibility of personalized treatment of the individual JME patient," concludes Dr. Schneider. "Life-long AED therapy is not necessarily required in many patients to maintain seizure freedom. Understanding the predictors for successful long-term seizure outcome will aid clinicians in their treatment options for those with JME.”
Provided by Wiley
Source: medicalxpress.com