If you’ve experienced a seizure, or any kind of unusual neurological symptoms, you’re probably wondering what steps you – and your healthcare professionals – will need to take to figure out what’s going on in your body.
Enter Neurologist and Epileptologist, Dr Lisa Gillinder, with an overview of the diagnostic process and what you can expect to happen next.
“You’ll go down one of two slightly different pathways, depending on your individual symptoms and where you enter the medical service,” Lisa says.
Emergency admission
“If it’s an acute presentation – say after a convulsive type of seizure – the ambulance might have been called and you’ll go to an emergency department. The emergency department will do an initial workup [diagnostic examination] to make sure that there’s no secondary causes of seizure, which will include basic things like blood tests and infection screens, and in some cases a CT head scan.
“If they haven’t found a secondary cause, and you’re medically stable, you’ll probably be discharged home for outpatient care, which will usually involve referral to a first seizure clinic. That’s all perfectly normal.
“Whether you’re referred to a neurology department or general medicine will depend on the services available in your local area. In addition to the outpatient referral, either the emergency department or treating physician will organise an EEG and an MRI.
GP Review
“The second pathway usually occurs if there’s some kind of event, like a faint or funny turn – not acute or concerning enough to trigger a presentation to an emergency department but something you’d usually take to your GP. The GP will do a basic assessment, determine that your symptoms are potentially neurologic and then make a referral to an outpatient neurologist, who at that point would then organise an EEG and MRI.”
Even with a witnessed seizure, diagnosis isn’t necessarily quick or straightforward, Lisa says, so a thorough investigation is essential.
Your Medical History
“The neurologist will start with a basic history to understand the nature of the events. What are they like and what symptoms or signs are they causing? Could they be consistent with seizures? Could there be another cause, like low blood pressure, irregular heartbeat or heart failure? Or is it actually neurologic? And if it is neurologic, is it a seizure or is it something else, like a movement disorder or a functional neurologic disorder?
“That’s usually what we’re trying to work through when we ask for a history of the events themselves. Then we’ll go through your background information, looking for epilepsy risk factors like family history, brain injuries or previous brain infections, febrile convulsions, strokes or other insults to the brain. Those sorts of things are really important and can increase the chances that you might have a seizure.
“We also look at your medical background to make sure there are no other predisposing factors. We’ll look at medications to make sure you’re not taking something that’s pro-convulsive or a medication that can lower your seizure threshold – the state in which your brain’s activity has changed enough that it might generate a seizure.”
Once a comprehensive history has been taken, Lisa says, they’ll begin specialist testing.
Brain Imaging
“The most important test is the EEG, which records the brain’s electrical activity. Our brain runs on electricity, so it’s normal for it to have different types of activity and frequencies in different regions. But if that activity becomes abnormally synchronised, that can generate EEG activity described as spikes or sharp waves, which we broadly classify as epileptiform-type brain activity. And that can be a pretty clear warning that your symptoms might be related to epileptic seizures.
“The other main thing we look at is an MRI scan of the brain, which is searching for structural causes of seizures. That is anything in the brain that disturbs the normal architectural function of the cortex – the grey matter of the brain – which has the potential to cause seizures.
“Many of the things we find in an MRI scan that are relevant to seizures are congenital [present from birth]. However, over the years of our lifespan, we also accumulate various ‘insults’, or injuries, to the brain that have the potential to generate seizures by causing a secondary type of epilepsy. These structural causes of epilepsy result in ‘focal epilepsy’. There are also other childhood and adolescent forms of epilepsy or genetic-type epilepsies which can cause ‘generalised epilepsy’, and in such cases the MRI brain scan might be normal.
“There are many types of congenital and inherited-type cortical malformations that can cause seizures; the other important thing we’re looking to exclude is potentially more sinister things like cancer. That is rarer but, as we age, that can be something we’re checking for more seriously.
The Path to Diagnosis
Once all the facts have been established, Lisa says, your clinician will start to form a picture of what’s going on.
“Depending on the history, the EEG and the MRI, the clinician should usually be able to give you an idea of whether they think it’s epilepsy causing your symptoms. Specifically, epilepsy can be diagnosed if there have been two or more seizures more than 24 hours apart. These must have occurred outside of the setting of a provoking cause or acute disturbance like metabolic problems, head injuries or acute stroke.
The criteria of two or more unprovoked seizures is used because we know, after two seizures have occurred, there is a much higher chance of going on to have further seizures. If your clinician thinks you meet that diagnosis, then they might immediately start talking about anti-seizure therapy, which is used to reduce the risk of having more seizures.”
Your Prognosis
While there is no ‘one size fits all’ for epilepsy diagnosis, or indeed treatment, Lisa says that these investigations often give clinicians a sense of what the future might hold.
“If this is your first seizure, depending on the EEG and the MRI results, we will usually be able to give you a reasonable estimate of what we think the chances of another seizure are,” Lisa says.
“If the EEG and MRI are normal, the chances of having a second seizure are around 20 or 30%, but if the EEG and MRI are abnormal, the chances are more like 50 or 60%. Once you cross that threshold of more than a 50% chance of having another seizure, even without having had multiple seizures, we will often begin to talk about starting anti-seizure medications.
Anti-Seizure Medication
“There’s been a lot of drug development over the years, so there’s now more than 20 different anti-seizure medications on the market. A lot of the newer generation medications don’t have long-term side effects associated with them. Things we used to worry about a lot in the past would be metabolic derangements [disruptions to the normal processes of the body], liver dysfunction, osteoporosis or blood cell abnormalities, but most of the newer medications aren’t associated with those sorts of issues.
“That said, all medications can be associated with side effects, so sometimes it’s tricky – as the patient you can feel like it’s a case of trial and error. If we try a first medication and you have side effects from it, then we have to start again and try a new one, and sometimes, depending on how sensitive you are, you might cycle through two or three medications before you find the one that’s the right fit. That can be quite frustrating and demoralising.
“For a new diagnosis, there’s a 70% chance that you’ll become completely seizure-free with medication. But after we’ve cycled through two different medications that have been well-tolerated and given at appropriate doses, if the seizures continue despite that, then the chances of becoming completely seizure-free with medication alone drop to around 10%. That’s when we classify epilepsy as refractory; refractory means that medical therapy is unlikely to result in complete seizure freedom.
“The need to take anti-seizure medications isn’t always lifelong. Sometimes we do get patients to a point where, if they’ve been seizure-free for many years, we will try withdrawing the medications. Some people are lucky that the epilepsy has resolved, but sometimes that’s not the case and the seizures will return.
“The other important thing to highlight is that anti-seizure medications are not disease-modifying. Currently, anti-seizure medications only offer symptomatic control and they don’t affect or ‘cure’ the underlying epilepsy, which means you’ll need to be on them in the longer-term.
“Hopefully future research will deliver medications that are actually going to be anti-epileptic, meaning that they can modify the underlying disease process and stop it from happening altogether. That would be the ideal outcome.”
Want to know more, or need additional support as you navigate your diagnosis? Contact our Living Well team on 1300 852 853 to find out how we can help.
