A Quick Guide To Focal Onset Seizures
This is part one of a series in which I cover various types of seizures, to give people who are new to epilepsy a good idea of what each one can look like… And I wanted to start by discussing focal onset seizures, since they’re the most common.
What are focal onset seizures?
Focal onset seizures are one of three potential seizure classifications; the other two are generalized onset seizures and unknown onset seizures. You may also hear focal seizures referred to as partial seizures, but this is an outdated term!
Essentially, a focal onset seizure is one that starts on only one side of the brain. Whereas generalized onset seizures, which we’ll discuss in a later post, start on both sides of the brain.
Types of Focal Seizures -
Now, within the category of focal onset seizures, there are multiple subtypes…
Focal aware seizures
Focal impaired awareness seizures
And either of these can be further divided by whether or not they involve motor symptoms
What do focal seizures look/feel like?
Obviously, the specifics of how a focal seizure will affect someone comes down to what type of focal seizure it is…
Focal Aware Seizures -
Focal aware seizures tend to be quite short, usually lasting less than two minutes. Furthermore, the person is completely aware of what’s happening during the seizure. With no loss of consciousness or confusion. During the seizure, they may…
Become nauseous
See hallucinations like flashing lights
Freeze and be unable to move or talk
Feel odd sensations throughout their body
Or start shaking in certain areas of the body
The area of the brain that’s being affected by the seizure will determine which of these symptoms the person experiences. And because of this, most people will have a specific set of symptoms that they deal with during most (if not all) of their focal seizures.
Focal Impaired Awareness Seizures -
Focal impaired awareness seizures can last several minutes, but during these seizures, the person affected will lose at least some amount of awareness. And in many cases, they won’t even remember what happened during the seizure! Additionally, they may feel tired or confused for some time after.
During the seizure, the person may…
Perform automatisms; like adjusting clothing or moving their mouth
Freeze completely and “stare” ahead
Or even cry, laugh, scream, or repeat words or phrases (this is somewhat rare)
How often do focal onset seizures occur?
Focal seizures can happen several times a day or rarely, it really depends on the person and the root cause of the seizures.
Are focal seizures dangerous?
Although focal seizures aren’t as dangerous as something like a tonic clonic seizure… they still carry some amount of risk. As all seizures do!
Firstly, because someone having a focal seizure could lose control of their body, they’re vulnerable to many things. It would be dangerous to drive, someone could take advantage of them, etc. Especially since people with focal impaired awareness seizures don’t always remember what happened during their seizure.
Secondly, they could do something dangerous during their seizure. Such as accidently walking into traffic, or burning themselves by touching a flame or a hot burner.
And lastly, because they can escalate into focal status epilepticus or even into a generalized tonic clonic (and therefore traditional status epilepticus), they can even be deadly in of themselves!
What causes focal seizures?
There are many potential causes for focal seizures, including…
Epilepsy (It’s important to note here that many different epilepsy syndromes and types of epilepsy can cause these seizures, there’s even focal epilepsies that cause these seizures exclusively)
Drugs and alcohol, or withdrawals from these substances
Aneurysms
Brain tumors
Brain injuries and concussions
Genetic disorders
High fever
Infections like meningitis
Sepsis
Degenerative brain conditions like Alzheimer’s
Strokes
Electrolyte imbalances
Structural issues within the brain
Or even inflammation caused by auto-immune disorders
How are focal onset seizures diagnosed?
First and foremost, many doctors will identify focal seizures off of description alone.
But that doesn’t mean that certain tests won’t be run to confirm the presence of focal seizures, as well as to find out where they’re stemming from. Because if the area of the brain where these seizures originate can be identified, treatment becomes easier.
Some of the tests you could expect would be…
An EEG (electroencephalogram); of various types… traditional, video, or even intracranial
And MRI (magnetic resonance imaging)
A PET (positron emission tomography) scan
A MEG (magnetoencephalography)
A blood test
A SPECT (single-photon emission computed tomography)
And potentially a spinal tap
Each of these tests are for specific scenarios, and usually one person won’t have to undergo all of them! Different ones are used for different cases…
How are focal onset seizures treated?
The treatments used for focal onset seizures can fall into two categories; treatment for “provoked” focal seizures and treatment for “unprovoked” focal seizures.
Provoked Focal Seizures -
Provoked focal seizures are ones that have a very distinct and treatable/avoidable cause. And the treatments for these can vary greatly, just as the list of potential causes for focal seizures vary…
Unprovoked Focal Seizures -
Treatments for unprovoked focal seizures on the other hand, tend to rely more on lessening the severity of the focal seizures and decreasing the frequency in which they occur. Focal seizures that are caused by epilepsy fall under this category, since epilepsy is technically “incurable”.
Potential treatments for this category of focal seizures could include…
Medication
Dietary changes
VNS (vagal nerve stimulation)
DBS (deep brain stimulation)
RNS (responsive neurostimulation)
Or even surgery, to remove the part of the brain where the seizures occur!
Conclusion
Focal onset seizures are a unique type of seizure that can occur in many instances, and for many different reasons… But I hope you found this article helpful, and that after reading it, you understand this seizure type a bit better.
Sources
As always, here’s a list of my sources… In case you want to dive further into the topic, or feel more assured that the information I shared in this post was factual.
https://www.hopkinsmedicine.org/health/conditions-and-diseases/epilepsy/types-of-seizures
https://www.epilepsy.com/what-is-epilepsy/seizure-types
https://medlineplus.gov/ency/article/000697.htm
https://www.epilepsy.com/what-is-epilepsy/seizure-types/focal-onset-aware-seizures
https://www.epilepsy.com/what-is-epilepsy/seizure-types/focal-onset-impaired-awareness-seizures
https://my.clevelandclinic.org/health/diseases/22893-focal-seizure
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