seizure files - what does this mean

[sarasmom]

Hi, my daughter Sara has suspected of having complex partial seizures. She recently had a 48 hour EEG which revealed 17 seizure files and 124 spike detections. We don't meet with her neurologist for another two weeks.

I do not know what "seizure files" are nor do I understand if the number of spikes is significant or in the normal range for complex partial seizures.

Any help is greatly appreciated!

[Nakamova]

Hi sarasmom --

The neurologist should provide you with a detailed discussion of what the EEG indicates, but essentially her EEG recorded 17 instances of what appeared to be seizures based on the pattern recorded. Repetitive spikes or sharp waves between seizures are often indicative of complex partial seizures, so that sounds consistent with your daughter's preliminary diagnosis. But other info on the EEG may also be relevant to the diagnosis -- how fast the spikes occurred, how closely bunched together, whether they alternated with waves or domes, etc. -- so really you need the neurologist to give you the full scoop.

[sarasmom]

Yes, I do plan to speak in depth with her doctor, it's helpful to develop questions first. Thank you so much for your reply.

I am a bit confused. The report states that the spikes are not epileptiform, so does this mean that they are normal spikes?

It states the EEG is abnformal because it contains intermittent sharp wave activity. From what I understand, these are indicitave of epilepsy but not seizures?

To clarify, "seizure files" mean seizures?

THANK YOU!

[Nakamova]

A seizure file is a portion of EEG with abnormal neural behaviour suggesting that there was a seizure occurring.

Even when someone isn't having a seizure, their brainwaves in between seizures might show a pattern that's characteristic of people with epilepsy, or particular kinds of epilepsy. In my case, I have tonic-clonic seizures. I didn't have any seizures during my EEG, but my brainwaves showed a pattern called "spike and slow wave" that's characteristic of generalized epilepsy. In your daughter's case, spiky waves between seizures are often characteristic of focal partial seizures, so it MIGHT point to that diagnosis for your daughter. On the other hand, if all the spikes are "non-epileptiform" they could be abnormal but not necessarily point to epilepsy. For instance migraines can produce spikes. Or they could be the normal spikes associated with the NREM period of sleep. There are so many variables that need to be taken into account with EEGs -- where and when particular waveforms occur, the frequencies, the background surrounding them, whether the patient is awake or asleep. And people without epilepsy or any other other neurological problems can have abnormal EEGs. People with epilepsy can have normal EEGs...

[Loopy Lou]

Wow, they really give you that much info on your eegs? My neurologist just said there were "epileptiforms" and wouldn't elaborate any further as to whether or not for definite i had any minor seizures during the eeg. I'm pretty sure i did though. That 45 mins felt like 10 lol.

[sarasmom]

I still need helping understanding what "seizure files" mean on my daughter's EEG findings. They were normal except for the sharp waves found intermittently. This would go along with the suspected diagnosis of complex partial seizures. I have just not heard the term "seizure files" and cannot find clear information. I was told they mean seizures took place and I have been told that seizure files do not mean seizures, just that waves that were epileptiform in nature were detected. I just met with my daughter's physician and I am still confused. Do seizure filed detected mean seizures themselves? ANY HELP is appreciated.

[Nakamova]

It's definitely confusing stuff -- I think a lot of neurologists don't bother to explain, or can't explain it clearly.

I hope this helps:

A "seizure file" can be recorded on EEG in two ways. One way is if the patient is holding a push-button device to push when they think they are having a seizure. When they push the button it's recorded as a seizure file. The other way is when the computer that is recording the EEG data sees a pattern that matches certain seizure/spike detection algorithms in its database. In this scenario, the computer is calling something a "seizure file" when it seems to match an existing pattern that it associates with seizures.

Other things to keep in mind:

1. A pattern on an EEG can be "epileptiform" without necessarily confirming a seizure diagnosis.

2. If the epileptiform pattern is "ictal" -- that is, occurs while the patient is having a clinical seizure (at that moment showing physical signs of a seizure, convulsing, being semi-conscious, confused, etc.,) then that points fairly strongly towards an epilepsy diagnosis.

3. But if the epileptiform pattern is "interictal" -- that is, does not appear during an actual seizure -- then it can be open to several interpretations. The presence of Interictal Epileptiform Discharges (IEDs) on an EEG is not by itself conclusively diagnostic of epilepsy.

The frequency of the IED on the EEG offers limited information. While it can increase after a seizure, it does not predict severity of epilepsy, and the relationship between IED spikes and seizure activity is not clear in every case.

Some more info about Interictal Epileptiform Discharges (IEDs):
According to various studies:
-- 2.2% of non-epileptic patients had IEDs
-- 2.7% of 743 normal children had IEDs during wakefulness
-- 8.7% of 743 normal children had IEDs during sleep

In addition, there are certain physiological activities that can be confused with epileptiform activities, mostly related to certain stages of sleep, or transitions between stages.

So... interpreting EEG data involves taking into consideration a lot of different factors. If there's clinical data -- actual seizure-like symptoms your daughter can describe -- then that combined with the EEG can go along way towards confirming an epilepsy diagnosis.