Why are these called focal seizures?

[samanthaash1993]

Hi. My Neurologist said to me, that my epilepsy comes from the right hemisphere, but if I had two tonic clonic seizures before my EEG, how are they focal? He says they are focal. If they were tonic clonic, how are they focal, because don't tonic clonics generalise? And move to both hemispheres? Although my EEG detected epileptic activity, even though I wasn't having tonic Clonic seizures, so that's how he was able to tell that my seizures were focal? So was he just going by my EEG, and CT scan, or from the descriptions of my two Tonic Clonics I had before being diagnosed over 2 years ago. I have been seizure free for two years. and not had an aura before my first, but had an aura before my second, which I don't remember. Although, before I was diagnosed, I used to get these funny spells, where I would have ringing in my ears, rapid heart rate, headache, dimmed hearing, like someone putting their palm of their hand over your ears, but inside, a heat cage all around me, sweating, nausea, light on my feet, agitated, and tired, as well as retching, and the urge to go to the bathroom. After them, I would feel very tired. Were these seizures? I had them when I was younger. My first TC was at 18. Before then, since I was 13 years old, and at random, I had these "dizzy spells" one in June 2006, one in july 2006, none in 2007, , , another in march 2008, none in 2009, one in 2010, and one in early 2011, before my TC in November 2011. My second TC was march 2012, and in august of that year, I was diagnosed with epilepsy. I have not mentioned the "dizzy spells" to my Neurologist yet.

[Dr Hannah Cock]

Dear Samantha,
you really need to ask your neurologist to get a definite answer with respect to your individual case, as he/she is the person who will have access to your investigation results (brain imaging, EEG), and your full medical history. You should also tell him/her about your other symptoms.

In general terms focal seizures are seizures which originate in one part of the brain rather than starting simultaneously in both sides/all over the brain (generalized seizures). There are several factors which can help point to whether seizures are focal or generalized in onset. These include - symptoms (e.g. warning symptoms that suggest a focal onset - the aura, or witness accounts of what happens during the seizure itself); brain imaging (CT or MRI - if it shows areas of scarring/other abnormalities of the sort known to sometimes cause seizures); EEG - which can sometimes show abnormal brainwave activity in one part of the brain (focal) or all over (generalized) even between seizures. The circumstances (e.g. age, previous history) can also be helpful - for example generalized epilepsies typically start in childhood/early adult life, whereas focal epilepsies can start at any age, and for epilepsy that starts later in life (e.g. 40s, 50s and beyond), a focal cause is more common.

In some people it is easy to know from the history alone which type of seizures (and thus which type of epilepsy) they have. Tonic-clonic seizures can be both generalized (starting in both hemispheres from the onset) or focal in onset, but spreading rapidly to both sides of the brain so that the main seizure looks identical (i.e. tonic clonic). In people who have only tonic clonic seizures, without warning or with non-specific warnings, and no other seizure types - it is not possible to know for certain on the basis of history alone whether they are generalized tonic clonic seizures, or seizure which actually do have a focal onset but spread so quickly to the rest of the brain that any warning is so brief that it is never remembered, or witnessed by others. In these cases investigations such as MRI and EEG can sometimes help determine the likely seizure type - e.g. if they show clear abnormalities in a focal pattern.

The other thing I should mention is that the "dizzy spells" you describe have several symptoms that would be unusual for epilepsy, and more typical of other causes of blackouts/funny turns such as fainting. As fainting is very common, especially in teenagers, it is very possible that this is something quite separate - but you should be sure to mention these symptoms to your neurologist. I say this because blackouts due to faints can sometimes look a bit like epilepsy (including with shaking/jerking - called convulsive syncope) and it is important anyone managing your blackouts/epilepsy has the full picture.

The good thing is you say you have been seizure free for 2 years - which is more important than whether these are focal or generalized in the grand scheme of things. If, because you are seizure free, you have been discharged and are no longer followed up by the neurologist - your GP may know the answer to your questions based on letters/information from the neurologist, and/or be able to write to the neurologist asking for clarification, or even a fresh appointment so you can ask him/her these questions directly.

Hope that helps,
good luck
Hannah

[Andrew Kelso]

If your neurologist is anything like me, he or she will have quite a short time to go through things with you at your appointments. All of the questions you have asked are relevant and important, and you should be able to ask them all and understand the answers when you see your neurologist. That might not all happen on one visit, and you might need to go a few times before you feel you've really got the bottom of things.

Consider writing down your questions and prioritising them, numbering them 1 -10 (or however many you have) in order of importance to you. This is to make sure that if you don't have time to ask everything you want, you've dealt with the most important issues to you.