Epilepsy & Seizures:
Introduction to neurons & seizuresNeuronsReceive signals (which reduces the voltage of a cell) from other neurons
-Passes on the signal only when its voltage goes below threshold level
-Receive signals (or action potentials) from other neurons
-Action potentials reduce the voltage of a cell
-Passes on the signal only when its voltage goes below threshold level
Seizures-Happen when normal signalling patterns are disturbed and neurons fire excessively
-Upon reaching muscles, lead to muscle movements, resulting in spasms
Epilepsy
What is Epilepsy-General term for group of disorders that cause disturbances in electrical signalling in the brain,
leading to recurrent seizures.
-Approximately 1% of world’s population have epilepsy
-Causes of epilepsy include: imbalance in excitatory and inhibitory neurotransmitters,
abnormality in genes, trauma to the head etc.
-However, the no causes can be identified in more than half of epilepsy cases
Effect on lives of patients-Epilepsy patients are not allowed to do many things
Laws in Singapore:-Not allowed to drive
-Not allowed to take certain courses such as engineering
-Epilepsy also hinders people with epilepsy in education and work
Education and work:-Only 15% of people with epilepsy finish collage
-25% of people with epilepsy unemployed
Current Solutions
Antiepiletic Drugs(AEDs)-Use drugs to control seizures, usually by enhancing production of inhibitory neurotransmitters
-Side effects range from milder ones vary such as dizziness, weight gain to more serious effects
like increased risk of depression, cardiovascular problems and osteoporosis
Vagus Nerve Stimulation(VNS)-Apply electrical stimulation to the vagus nerve at regular intervals to reduce frequency and
severity of seizure, though exact mechanism of action is not known yet
-Less than 50% of people have substantial reduction in number of seizures with VNS
-To be used alongside AEDs, thus patients suffer from adverse effects of both the drugs and
VNS
-Causes throat pains, hoarseness of voice etc. when electrical stimulation is applied
Surgery-Prevent seizures by removing part of the brain responsible for erratic impulses
-About 75% of patients that undergo surgery for epilepsy become seizure free
-Lose functionality of the part of the brain removed
-However, more than 35% of patients with epilepsy are still unable to control seizures with all of
today’s best treatments.
Our Solution-A system that detects seizures and actively prevents it from happening, using a combination of
ECoG and optogenetic methods
Optogenetics-Using genetic techniques to control neural activity
For our solution:-Usage of photosensitive proteins (opsins) that act as chloride or proton pumps when activated
-Moving protons or chloride ions out of the neuron increases the voltage of neuron, preventing it
from firing by keeping voltage of neuron above threshold value
-Studies shown that it can achieve 99.8% silencing in brain activity
Detection System-Plant electrodes on the exposed surface of the brain
-When seizures happen, electrical activity in brain will increase
-If readings go past a threshold level, seizure is taking place, thus device will activate, where a
optical fibre will light up to activate the opsins in the neurons
Full Solution-Patient will undergo brain mapping as used in current epilepsy treatments to find part of the
brain that is causing seizures
-Virus specifically targeting neurons in affected area carrying gene to make the cell express an
opsin injected; targeted neurons with the opsin will be silenced when exposed to light
-Brain surgery to plant the device in the head
-In summary, device will pick up when a patient is having a seizure and lights up the optical
fibre, exposing the neurons to light and stops neurons from firing, thus preventing impulses from
reaching the muscles and in turn, preventing seizures
Advantages over other solutions-By actively preventing neurons from firing when seizures are picked up, should be able to
completely prevent seizures from happening in all cases
-Mechanism of action does not affect other body processes, and does very little to the neurons,
thus there should not be long-term side effects and minimal short term side effects
Please comment. Thanks
