Understanding Epilepsy

Epilepsy means seizure disorder.

So people with epilepsy have recurring and unpredictable seizures. A seizure is a period where a cells in the brain or neurons are a synchronously active or active at the same time when they're not supposed to be. Now when I say neurons are active, I mean that they're firing or sending a message using electrical signals relayed from neuron to neuron. 

And if you look at a neuron under a microscope each electrical signal that passes through it is really just ions flowing in and out through protein channels. 

The way this ion flow is controlled is through neurotransmitters (a type of signaling molecule) and receptors. Neurotransmitters bind to The receptors and basically tell the cell to either open up the ion channels and relay the electrical message called excitatory neurotransmitters or close the ion channels and stop the electrical message called inhibitory transmitters. 

During a seizure clusters of neurons in the brain become temporarily impaired and start sending out a ton of excitatory signals over and over again. And these are sometimes said to be paroxysmal. These paroxysmal electrical discharges are thought to happen due to either too much excitation or too little inhibition which are kind of two sides of the same coin, right?

The main excitatory neurotransmitter in the brain is glutamate and NMDA is the primary receptor that responds to glutamate by opening ion channels that let calcium in, a positive ion that tells the cell to send signals. 

Some patients with epilepsy seem to have faster long-lasting activation of these receptors on the flip side.

The main inhibitory neurotransmitter in the brain is GABA which binds to GABA receptors that tell the cell to inhibit the signal by opening channels that let in chloride ions, which are negative ions that tell the cell to inhibit signals. Some patients with epilepsy seem to have genetic mutations in which their GABA receptors are dysfunctional and so they are able to inhibit signals in addition to potentially having a primary genetic cause though these receptors and ion channels might be affected by all sorts of things like brain tumors, brain injury or infection. 

Whether it's a decrease in inhibition or an increase in activation, when groups of neurons start firing simultaneously over and over it's often noticed by others as obvious outward signs, like jerking, moving and losing consciousness, but can also be subjective experiences that are only noticed by the person experiencing it like fears or a strange smells. It all depends on which neurons in the brain are affected.

People with epilepsy experience recurring episodes of some form of seizures and we can start grouping the seizures by the region of the brain that's affected. When the affected area is limited to one Hemisphere or one half of the brain or sometimes even a smaller area like a single lobe. We call it a partial or a focal seizure.

These seizures just can be sub categorized by whether someone remains conscious during the seizure which is called a simple partial seizure or whether someone has impaired Consciousness during the seizure, which is called a complex partial seizure. Simple partial seizures typically affect a small area of the brain and can involve the person experiencing strange Sensations like hearing or tasting something but can also involve jerking movements in specific muscle groups at the neurons controlling those muscles are affected if the jerking activity starts in a specific muscle group and spreads to surrounding muscle groups as more neurons are affected. It's referred to as a Jacksonian March. 

Typically, the person is conscious meaning that there are awake and alert and will usually know that something's happening and we'll remember the seizure afterwards complex partial seizures on the other hand involves losing Consciousness completely or having impaired awareness and responsiveness. So they might not remember exactly what happened during a seizure. 

Now in contrast to the partial or focal seizure, a generalized seizures were both hemispheres of the brain are affected.

Sometimes the seizure will start out as a partial seizure and then quickly develop into a generalized seizure. And in those situations would be called a secondary generalized seizure because a partial seizure came before it and was the primary event. 

Just like partial seizures. There are some subcategories of generalized seizures as well.

One subtype is a tonic seizure where the muscles all the sudden becomes stiff and flexed which can cause the patient to fall often backwards on the flip side though. They can be a tonic as well or their muscles suddenly relax and become floppy which again can cause the patient to fall but this time forward seizures can also be clonic where they have violent muscle contractions also known as convulsions tonic-clonic seizures are the most common generalized seizures where patients experience a tonic phase where the muscles suddenly tense up followed by a clonic phase where the muscles rapidly contract and relax. 

Myoclonic seizures are yet Another type and are short muscle twitches. Sometimes just a single twitch, but sometimes many in a short amount of time.

Finally, there are absence seizures where the patients lose consciousness and then quickly regain consciousness. Generally with the only outward sign being that the person looks like they spaced out like if there are walking they'll suddenly stand still.

The key for all these is that they involve both hemispheres of the brain and patients lose Consciousness either briefly or for longer periods of time. 

If the seizures do last for a longer period of time like over five minutes of ongoing seizures or having multiple seizures without returning to normal in between then it's called status epilepticus.

And these are usually the tonic-clonic subtype of seizures, but it can also be caused by other types that don't involve convulsions. This situation is considered a medical emergency and can be life-threatening if not treated immediately.

Due to the severity of these seizures patients are often treated acutely with benzodiazepines which helped enhance the effect of the inhibitory neurotransmitter GABA.

Following a seizure sometimes patients experience certain symptoms like confusion called postictal confusion, which means after seizure confusion. Also patients might experience paralysis that affects the arms of the legs usually just limited to one side of the body and this is known as Todd's paralysis or Todd's paresis and can last for quite a while on average about 15 hours.

And usually it subsides by itself completely after two days the precise mechanism behind cause paralysis isn't currently well understood.
But it's not to be the result of temporary but severe suppression of activity of the area in the brain affected by the seizure. Typically after a seizures over patients will have brain imaging techniques like MRI or CT scans as well as an EEG or electroencephalogram which detects electrical activity in the brain.

With patients who have just started having seizures brain scans are used to find out if there are any anatomical abnormalities like brain tumors or abnormal blood vessels that could be causing the seizures both of which would be treated surgically. Because epilepsy can vary from patient to patient in the type severity and frequency of the seizures, diagnosis typically involves a variety of examinations and tests in combination with a thorough evaluation of their clinical history.

Once epilepsy has been diagnosed. It's often treated with daily medication the primary form of medication being anticonvulsants, of which there are a wide variety of options available that have different targets in the brain.

So the choice is based on the specific needs of the patient including factors, like age, lifestyle, other health problems and the category or subcategory of the epilepsy syndrome.

Other treatment options include epilepsy surgery where they'll remove what's thought to be causing the seizures like a specific part of the brain or a tumor.

Nerve stimulation might also be considered where a certain nerves like the vagus nerve are stimulated, which is thought to control seizures by influencing neurotransmitter release.

Also patients might adopt a ketogenic diet, which is a diet that forces the body to burn fat instead of carbohydrates, which produces Ketone bodies which are then used by the brain as an energy source instead of glucose. Although many hypotheses have been suggested for why the seems to reduce seizures for some patients, the exact mechanism isn't very well understood.

If you're interested in a deeper dive on this topic take a look at osmosis.org where it has flashcards, questions and other awesome tools to help you learn medicine.