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,
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
And a seizure should
the semiology what
happens should be the same
every single time for
that patient's seizure.
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
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
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
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,
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
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.
REM behavior disorder and parasomnias
can mimic nocturnal seizures.