In this lecture, we're going to talk about an introduction to seizures and epilepsy.
This is a really important topic, relevant both clinically and for vignettes.
And we'll talk about how we approach seizures, what they are,
how we approach epilepsy and what that is.
Let's start with, what is a seizure?
It's a sudden uncontrolled electrical disturbance in the brain
that results in a change in behavior, movement, sensation,
consciousness, or some other neurologic function.
When we think about seizures,
seizures are different person to person.
Seizures differ in their appearance and do not resemble each other.
So one person seizure may look very different from another person's seizure.
Classically, we think about the seizures where someone passes out,
jerks and shakes all over,
and maybe incontinent or bite their tongue.
But sometimes seizures are much more subtle,
and may show up as a brief period where someone stares off
and isn't able to converse or attend.
So seizures between each person may look different.
But within the same person,
the seizure should always look the same.
Typically, each seizure has the same appearance,
and that we call the seizure semiology.
And a seizure should be stereotypic,
the semiology what happens should be the same
every single time for that patient's seizure.
Importantly, seizures are stereotyped,
meaning that each event follows that same pattern.
And when we're evaluating patients on a history,
when we're interrogating whether we think this is a seizure or not,
determining that it is stereotyped is critical
to making a diagnosis of seizure.
What happens in a seizure?
What's the seizure trajectory?
What a patient's describe and as clinicians,
what are we looking to determine when we take a history?
When we think about the seizure phase over time, seizures have multiple phases.
There's the aura, that initial phase, that warning or trigger sign
that a patient recognizes that may mean that a seizure is going to happen.
Or as can have many different appearances,
many different behaviors, many different descriptions,
but typically, the aura is always the same, it's the onset of the seizure.
Then there's the ictal onset,
that's when the seizure is driving that area of brain
and patients will have manifestations of the actual seizure semiology.
This is followed by the ictal phase that ictal phase,
we classically think about is a period of jerking of tonic or tonic clonic activity,
but the ictal phase can take on the appearance
of any part of behavior or brain.
And then this is followed by the postictal phase,
where there's depression of brain activity in the area that was seizing.
And in the classic case, patients are very confused
and sleepy for somewhere between 15 min to up to 2 hours in some situations.
And so all seizures will follow this sequence of
aura, ictal onset, ictal phase and postictal.
We may not be able to recognize each of those clinically for all seizures,
but we're looking to evaluate those in the patients that we meet and evaluate.
What happens on the brain?
What's going on in the electro encephalography, the brain,
what's going on with the brain waves during a seizure?
What we look at the grand mal pattern of seizure, this is what we see.
Over on the left, we see that the normal brain
has very low amplitude, sporadic and erratic activity.
There's really no pattern with normal brainwave activity.
When the seizure begins, we see a spike.
And that spike indicates that there is the onset of the seizure.
And for a grand mal seizure, we begin to see the tonic phase,
where each of those spikes corresponds to a jerk in patient movement.
This then gives way to the tonic clonic phase, the clonic phase.
And there on the EEG, we see spike and wave, spike and wave,
corresponding to the jerking and rest and jerking and rest
that we see when a patient is in the clonic phase of their seizure.
And then this is followed by post ictal depression
and we tend to see that the brainwaves become very low amplitude almost silent,
almost quiet in this postictal phase
when the brain is very depressed after a seizure.
And so the EEG, what's happening on the brain
really maps closely to what we see and hear
from patients in the semiology of a seizure.
So if that's a seizure, well then what is epilepsy?
Seizure and epilepsy are different.
The seizure we said was a sudden event with variable clinical features.
Epilepsy has a number of different descriptions over time.
It's a neurologic disorder that results in repeated unprovoked seizures,
and that's probably a historical definition.
If we look back in antiquity,
epilepsy was described as the falling sickness.
And so even very early in our history,
there was a recognition that seizures could and epilepsy could take hold of patients.
The classic description, the classic definition of epilepsy
is 2 or more recurrent stereotypic unprovoked seizures.
So there's many important things in that definition.
Seizures must be stereotyped.
Classically, they are unprovoked, there's no cause,
and patients must have 2 or more.
Anybody can have 1 seizure, but 2 becomes a diagnosis of epilepsy.
For me, I tend to use a definition similar to this
a condition characterized by a predisposition
to recurrent stereotypic seizures of a central nervous system origin.
And I like this because we see epilepsy,
multiple recurrent unprovoked seizures,
or multiple recurrent seizures from patients
who have tumours or strokes, or other condition
that allows us to consider all of those in our diagnosis of epilepsy.
The key thing when we're differentiating between seizures and epilepsy,
a seizure is a one time event,
epilepsy or recurrent stereotypic seizures that come from the brain.
But before we get to a diagnosis of seizure,
we really start with the patient's clinical description of the event of the spell.
A spell is not something that the witch doctor conjured up.
In medicine, we use the term spell to describe a paroxysmal event
of altered brain function.
And spells may come from epileptic phenomenon, they may be a seizure,
or may be non-epileptic.
And our first job as a clinician or when evaluating a clinical vignette
is to figure out whether this spell is epileptic
in origin is a seizure or is non-epileptic.
So what's the differential diagnosis for a spell?
Maybe an epileptic seizure
or maybe a non-epileptic event.
Non-epileptic events may be non-epileptic behavioral events of functional diagnosis
or may come from a seizure mimic that's not of an epileptic origin.
And the list of those potential seizure mimics is quite long.
Syncope, and specifically convulsive syncope
can masquerade as a seizure.
Typically, we know that seizures start with altered awareness,
alter behavior and even convulsion followed by loss of consciousness,
whereas convulsive syncope begins with the fainting
followed by the convulsion and typically there is a period
where the patient has fainted and is not yet convulsing.
In addition, the postictal phase can differentiate convulsive syncope
from an epileptic seizure.
We know that in the postictal phase of a seizure,
patients are very confused and altered for that 15 min to 2 hours,
whereas with convulsive syncope, there is not postictal confusion.
Patients come right back to.
Migraines can sometimes present and mimic a seizure
particularly the aura around migraine can sometimes
be very similar to the aura of a seizure.
Transient ischemic attacks.
Recurrent episodes of cerebral ischemia can mimic seizure.
Breath holding spells and children panic attacks.
There are movement disorders that can occur during daytime or nighttime
that can mimic seizure paroxysmal dyskinesia episodes
where patients have abnormal and excess movements,
a tic disorder or hemifacial spasm which is jerking of the face
can also mimic a focal seizure.
Paroxysmal sleep disorders, narcolepsy,
REM behavior disorder and parasomnias can mimic nocturnal seizures.