by Harry Ingledew (Newcastle Medical Student)
with the occasional interruption from me
What are seizures? – an Archie intro
Put simply, and I am a simple person, a seizure is an electrical surge in the cortex – or at least that is one way to look at it. Basically, if I strap EEG leads onto your head, there will be a screen full of electrical squiggles (see below). Usually, they are all over the place and you have to have a different sort of degree, and a better quality EEG than mine, to make sense of them.
I used to think the seizure was a chaos of activity but, actually, if you look at the tracing above, it is sort of the opposite. It’s almost as if suddenly, the complexity of cortical impulses, with all their nano-nuances, has been replaced by a rhythmical, coordinated electrical march across the brain. Little wonder that, when this happens, people behave oddly.
Turns out, we function best when our brains are all over the place!
Watch these two videos that illustrate how order can erupt from chaos. The first still perplexes me but I try to imagine, as the nails in the box line up, the same thing happening to some folk in the build up to a seizure.
The second is 2 of my kids on the swing. I should really have anchored it a bit better! When they swing out of phase, all is fine. When they swing in phase, it’s like the frame is about to tear out of the ground.
So, the deal is that there are loads of reasons for people to have seizures, and there are loads of different types of seizures. It can get pretty confusing if you are not careful. At it’s core, however, the concept if simple.
The next step is getting a handle on the different types of seizures that you might meet in your career as a doctor.
Types of seizure (over to you Harry)
Right, so now we all know how to differentiate between a seizure, syncope, or non-epileptic attack (at least in theory), we can delve deeper into the types of seizure that patients can present with.
There are 2 main categories into which seizures can fall: focal and generalised.
Focal seizures occur due to abnormal electrical activity that is restricted to a certain area of the brain – this can be a small area of cortex or extend to encompass much larger areas. By definition, it never involves the whole of the cortex, however.
Focal seizures are subdivided into those in which the person does and does not retain awareness (as opposed to generalised seizures in which patients always lose awareness). Therefore, if a patient has any memory of their seizure it must have been, at least initially, focal.
this is a really crucial point and often glossed over. if you ask the right questions of your patient, and the witness, you can often not just diagnose the seizure but also whether it has a focal onset.
Focal seizures in which the patient experiences a consistent, stereotyped warning each time may be due to a structural lesion. It is therefore useful to understand how focal seizures in each of the lobes present, as it can help to locate a lesion before even seeing a scan.
Conversely, if the warning changes with each seizure, it becomes less likely that a structural lesion is the source of the problem.
Focal seizures can present with a myriad of weirdness; the type of weirdness depends on the area of the brain in which the electrical activity is occurring.
- Frontal – the frontal lobe is tasked with a wide array of functions including being home to the motor centres and the control of behaviour and personality. Seizures in this area therefore include motor phenomena and changes in behaviour.
- Parietal – the parietal lobe is mostly concerned with understanding sensory input; therefore, parietal lobe seizures may include feelings of warmth / tingling down one side of the body.
- Occipital – seizures with a visual onset, often explosions of light or colours. Like a migraine aura but much shorter and more dramatic.
- Temporal – seizures of the temporal lobes present with lots of very strange behaviour called automatisms which include actions such as lip-smacking, chewing, and blinking. As the temporal lobe is involved in memory, strange phenomena such as déjà vu (the feeling of having already experienced the current situation) and jamais vu (a feeling that the situation is very unfamiliar) may also occur.
Focal seizures often remain focal, but can progress and become generalised.
You can see an example of a focal seizure in the lecture I mentioned at the top of the page.
Generalised seizures occur due to abnormal electrical activity that engulfs the entire brain, and is not restricted to a single hemisphere. Patients typically do not receive any warning of an incoming generalised seizure and, after the event, they will have no memory of what occurred (other than feeling terrible).
There are many types of generalised seizure, but there are 2 key types to learn:
Absence – previously called “petit mal”, and often still referred to as this by patients. When was the last time you found yourself daydreaming? When we daydream, which for most people occurs every day, we are often described as being “absent”. This is very different however, from an absence.
An absence is a type of generalised seizure in which the patient suffers a brief loss of awareness. Absence seizures almost always begin in childhood and the classic story is of a child who will completely stop talking in a conversation, stare blankly for 5-10 seconds and then “3, 2, 1, they’re back in the room”, continuing where they left off with no awareness that they just had a seizure.
Have a look at these two videos. They show how brief the attacks can be. Hyperventilation can bring them on and this is often used during EEG recordings to increase the diagnostic yield.
Generalised tonic-clonic (grand mal) – This is what most people think of when they think of a seizure. But what does it actually mean? Well, lets break the name down. As we said earlier, “generalised” means the entire brain is affected, the patient gets no warning, and no memory after the event. First there is a “tonic” phase in which the person will go completely stiff and fall to the ground. Then comes the “clonic” phase, in which all 4 limbs will begin to convulse violently, often resulting in injury to themselves and people around them.
If you see one of these as a doctor, try to make sure that you describe it in as much detail as possible. It's really annoying if people just write "GTC x1" in the notes. Far better to say "patient sent stiff, arched neck and back, let out a tight cry, arms extended, legs extended, stiff for 30 seconds, not responding, then jerking of arms and legs, blue lips, low sats, then cessation over 60 secs, gradual recovery over 5-10 minutes but confused and agitated". The second description helps me in the next day, and possibly forever more!
Here is a good example of a generalised tonic-clonic seizure. Notice all the different phases of the attack (and how calm the nurses are – no need for a crash call!). The head turn might suggest a focal onset, just for the record, but with very rapid generalisation.
It is possible to make it a tonne more complicated, and there is an relentless desire to keep reclassifying things, seemingly just when everyone had got the hang of the last classification.
Currently, this is the "official" International League Against Epilepsy classification (2017). Bet they reclassify it again soon, just to keep us on our toes.
|Focal seizures affect one part of the brain, generalised affect both hemispheres|
|If they get a warning or have a memory it is focal|
|Focal seizures may be due to a structural lesion, particularly if the warning is consistent|
|The symptoms of a focal seizure help to locate the problem|
|Being absent is different from an absence seizure|
Epilepsy – what is it?
So, we have spoken a lot about the types of seizure people can have, but we haven’t actually mentioned epilepsy at all. This is because simply having a seizure doesn’t necessarily mean it is epilepsy. Epilepsy is the tendency to have recurrent seizures.
Epilepsy is very common, affecting around 600,000 people in the United Kingdom.
Epilepsy can occur for a vast array of reasons, but the exact cause is not found in many. Underlying brain diseases that can result in epilepsy include:
- a genetic predisposition
- brain injury – stroke, trauma, bleed, AVM
- developmental abnormalities
Older age at onset of epilepsy increases the likelihood that the cause is a structural lesion. These patients will receive a CT or MRI scan to rule this out – preferably an MRI in this day and age.
There are many types of primary epilepsy syndrome but, unless you’re a consultant neurologist (in which case you wouldn’t need me to explain any of this to you), there is no reason for you to learn them all. There is one, however, that is worth learning a little bit about – Juvenile Myoclonic Epilepsy (JME).
this is because within JME are lessons for how to approach the history, examination and investigation of all patients with epilepsy
- Onset is in adolescence (<30 years of age)
- Everyone with JME has myoclonic jerks (rapid, short-lived, uncontrolled movements), particularly when tired, typically when first awaking in the morning. They often report dropping their breakfast or spilling their tea soon after waking up. This is different from the physiological twitches and jerks many of us experience as we drift off to sleep, so please don’t go self-diagnosing with JME.
- Generalised tonic-clonic seizures are also common in JME
- Patients with JME often also have absence seizures
- JME can be diagnosed via an EEG as it has a very classical trace (more about this later)
The diagnosis that a blackout event is a seizure, rather than syncope, is often a clinical decision. A history of recurrent seizures is therefore indicative of epilepsy. It is important, however, to try and establish the cause of the epilepsy to rule out any serious, underling brain disease.
Despite the array of complex, often unnecessary, neurological tests that are often all too tempting to order straight away, when a patient presents with any kind of blackout the most important first test that should always be done is an ECG, to check for common cardiac problems that cause blackouts. A full cardiac assessment, including a 24-hour ECG trace and an echo may also be necessary.
Scans of the brain such as CT and MRI can be used to look for structural problems in the brain that may be causing the seizures. A consistent warning indicates the seizure is focal, meaning there is a focus, therefore potentially a lesion that could be identified on a scan.
To use one of Dr Archibald’s favourite phrases, an EEG (Electroencephalogram) “is as useful as a chocolate teapot” in most situations.
If a patient has presented with what clinically sounds like a frontal lobe seizure, and an MRI is done showing a tumour in the frontal lobe, an EEG isn’t going to add anything useful to the scenario.
There are, however, times when an EEG is useful. Some primary epilepsy syndromes, such as JME, have classic EEG signatures. As a rule, the younger the patient, the more likely the EEG will help.
There is an endless list of potential treatments and medications for epilepsy and understanding them all would be incredibly complicated – so don’t bother!
The good news is that for many patients with epilepsy, a single drug can stop their attacks. It can get much more difficult after that, but there are reasons for optimism when starting out, particularly if investigations are reassuring (no structural cause on MRI).
Many anti-epileptic medications have side-effects, including confusion, headache, tremors and weight gain. As well as these some are teratogenic, causing foetal malformation if taken in pregnancy. Medications like sodium valproate should be avoided in all women of childbearing in age, because of this, and there is a concerted effort to ensure this is the case in the UK.
There is, however, a nice simple rule that will help you choose the right medication for your patient, if you find yourself in the rare situation of needing to start a patient on anti-epileptic medication as a junior doctor.
“If it doesn’t begin with L, then don’t prescribe it”
Lamotrigine and Levetiracetam (commonly called Keppra) tend to be best tolerated and are often effective for both focal and generalised seizures – they are great all-rounders. They are not without their own problems, of course, but this is a decent rule of thumb.
The management of epilepsy during pregnancy is a balancing act. Too much medication increases the risk of foetal malformations, but reducing the medication too far increases the risk of having seizures, which in-turn can also cause damage to both mother and foetus.
it is beyond the scope of this article to cover a definitive guide to epilepsy management, and better brains than mine are required. I will put some links that you might find helpful at the bottom.
Status epilepticus (SE) is a medical emergency in which a seizure lasts more than 5 minutes, or there is incomplete recovery between subsequent seizures. Previously, SE was defined as a seizure lasting more than 30 minutes, but this was changed in order to ensure earlier treatment. The earlier you can intervene the better – seizures beget seizures so letting them run too long means they are harder to stop, and have worse effects on the brain itself.
SE either occurs due to pre-existing brain disease or a new change in the brain. It is therefore vital to find the underlying cause in a patient without a diagnosis that could explain the SE.
Prompt management with a benzodiazepine, such as IV lorazepam is vital, preferably as soon as SE is suspected. Buccal midazolam is often given pre-hospital by paramedics. If benzos fail to control the seizure, IV phenytoin should be used but, hopefully, senior help has arrived by then and as a junior doctor you shouldn’t need to give this. Often, if the phenytoin doesn’t work then your patient is on their way to ICU.
don't fiddle about with crappy little doses of iv medication in status. if you are gonna load, LOAD! As a rule of thumb, most adults with decent kidneys and livers will need around 1.5g of iv something (phenytoin, valproate, levetiracetam). It doesn't really matter what (as long as it's not iv bleach, Donald)
This link to the NICE guidelines isn’t pretty, but it does cover the standard approach in the UK.
The SIGN guidelines are often a bit more readable. This link will take you there.
Sudden unexpected death in epilepsy (SUDEP)
If well managed, most people with epilepsy will have a normal life expectancy. Sometimes, however, a person with epilepsy may die during or soon after a seizure for no apparent reason. SUDEP most commonly occurs while a person is asleep. Around 1/1000 patients with epilepsy may die unexpectedly.
SUDEP tends to be more common in those who experience frequent GTC seizures and those whose epilepsy is poorly-controlled. Better seizure control, with good compliance to an appropriate medication regimen, is therefore the best way to prevent SUDEP.
Don’t worry about this, but I thought it was worth having an awareness that many neurological disorders can cause problems with driving and require notification of the DVLA.
When someone has a blackout of any kind, fulfillment of all of the 3P’s are the key to being allowed to continue to drive. They indicate that the event was almost certainly provoked syncope, rather than an unprovoked seizure, making driving much safer.
Make sure you get the 3 P’s straight in your head, and in the notes, and you will be well on your way.
- Posture – the blackout occurred during a change in posture, such as rapidly standing up from a chair, or a prolonged period of standing
- Prodrome – the event was preceded by feeling warm, nauseous, and unwell
- Precipitating factors – the event happened at a time of pain, fear, or stress, such as when having blood taken
Driving is a crucial consideration after a seizure or blackout. Always check if your patient drives and, if they do, tell them they need to stop until they have spoken to the DVLA. Remember, it is the DVLA that ultimately license us to drive - not you. You must be clear in both your advice and your documentation of this advice.
This link takes you to the DVLA guidelines. It is often helpful to look at these with your patient, so they know what to expect.
Useful references and articles
Useful article on the first fit, and how to approach it.
These “Bare Essentials” articles always age well and this is no exception. Worth a read.
A tour de force in the Lancet – you will need your best library access for this one I’m afraid – they are mean at the Lancet!