Epilepsy Case Presentation and Diagnostic Process

A key opinion leader presents the case of a 16-year-old male with epilepsy, and considers the diagnostic process to accurately determine the classification. 

Trevor Resnick, MD: The case that forms the basis for this discussion is a 16-year-old boy who presents with a convulsion while eating lunch at school. And the convulsion started with him flinging his soda up into the air. He had no prior history of any risk factors other than sensitivity to bright lights and video games.

He was seen by a neurologist. The neurologist did an examination, some blood testing, an MRI, which was normal, and then did an EEG [electroencephalogram], which demonstrated a 4-Hz generalized spike-and-wave pattern, and a photoparoxysmal response at flash rates of 12, 14, 16, and 18 Hz.

Two months after that first incident he had another convulsion, and his teachers reported that he would stare into space in class. He was ultimately diagnosed with partial seizures, with secondarily generalized tonic-clonic seizures. He was initially treated with levetiracetam, 500 mg twice a day, but soon after starting therapy he experienced fatigue and dizziness, and his parents observed that he was more aggressive, more irritable at home, and this was also being reported to the parents by his teachers.

If we put the EEG aside, because the EEG is part of the testing that takes this from a diagnosis of a seizure or 2 seizures and moves it in a direction of a classification of an epilepsy or an epilepsy syndrome. And there are various things that can do that. It can be either an EEG, it can be an imaging study, it can be a genetic mutation. It can even be family history. All these things go into the piece of the puzzle that enables us, or sometimes doesn’t enable us, to make the diagnosis of an epilepsy syndrome.

In this case we have 2 clinical seizures in a previously healthy adolescent who then has an EEG that provides additional information. If we take it a step at a time, the first piece of information is that he has a seizure that is characterized initially by him throwing a soda into the air, and then him having what is described as a generalized tonic-clonic seizure, and then a week later another similar seizure.

If we start at the top and we say, “OK, this is a seizure that clinically looks like a generalized tonic-clonic seizure, the first question is, is this a generalized seizure, or is this a focal seizure that has evolved into a generalized seizure?” And with the information that we have from the clinical story, one would have to say, “I don’t know, it could be either.”

And then the question is, “Well, how do we then look into it further?” Looking into it further to see whether it’s one or the other would require either more clinical information, which we don’t have, or additional tests like an EEG and/or an MRI. In this case the only information we have is an EEG, and the EEG shows findings that are very typical and consistent with a generalized seizure, and not a focal seizure evolving into a generalized seizure. I think that’s the first point of discussion in this case.

It’s perfectly reasonable under the circumstances to say, this adolescent had a generalized seizure, and I don’t know whether it’s A or whether it’s B. However, after you’ve done the EEG, then it would be more appropriate to say the EEG findings are more consistent with a generalized seizure, and therefore, he would have to be treated as if he had a generalized seizure.

Video EEG monitoring is a significant tool that we use in diagnosing patients with epilepsy, or in characterizing the nature of the seizure. This case that we’ve been discussing, assuming the EEG wouldn’t have shown us something that was classic for a generalized seizure, assuming it was normal and the patient was having more frequent seizures, a video EEG may have helped us to characterize the nature of the EEG because it’s a longer study. And also, to be able to capture these episodes and enable us to actually diagnose a more specific epilepsy syndrome.

The other scenario is in patients who are having events that appear to be seizures but are not clearly seizures, and under those circumstances video EEG may enable us to discriminate between one and the other.

Another question that comes up, and it comes up in this patient as well, is what tools do you use to get the maximum information from the patients to come up with a diagnosis that is as specific as possible? In many cases you can’t do that. But that’s often where you have to go back in terms of the clinical history, where if you’re suspicious that they have a specific seizure type, you are going to ask about certain things in the history that the patient may not have volunteered because they thought they weren’t important, or they’re so overwhelmed with having had a generalized tonic-clonic seizure that they don’t think to mention the other issue.

I think added clinical information is really important. Family history is significant. Especially in 2020, highly evolved genetic mutation testing that’s ever expanding has provided us with a diagnosis of a genetic mutation as the cause of the patient’s seizures that really wasn’t available to us 20 years ago. And our ability to say this patient has generalized seizures with this specific mutation is a very different way of describing epilepsy than it had been previously.

So genetic mutation testing, imaging studies, family history, clinical history, EEG, a lot of those things we already had, but being able to add these other parameters in has allowed us be much more specific with a diagnosis.

To get back to this adolescent, in this case if you weren’t sure whether the seizure was focal at onset or generalized, then doing an imaging study would be perfectly appropriate to see if there was structural pathology that was causing the patient’s seizures. Once you have an EEG that demonstrates a generalized spike wave on the EEG, the likelihood of the imaging study providing any additional information is very small. This is the kind of case though where doing genetic mutation studies, or an epilepsy panel, may provide additional information, especially if there’s a positive family history of seizures.