00:01
In this lecture,
we're going to talk about
the approach to disequilibrium
and the cerebellum.
00:07
When we're evaluating patients
with dizziness,
one of the first steps
is to determine
whether that dizziness is vertigo
coming from the vestibular system,
disequilibrium coming
from the cerebellum,
or syncope, presyncope
coming from other causes.
00:22
And in this lecture,
we'll focus on that
second evaluation
disequilibrium and the approach
to the cerebellum.
00:31
As an overview, where are
we headed with this lecture?
When evaluating these patients,
we start with the description.
00:37
And we want to understand whether
the patient's talking about
disequilibrium, vertigo,
or syncope, presyncope.
00:44
Those descriptions
that we look for from patients
that hone us in on the
cerebellum and disequilibrium,
our sensations of drunkenness,
a feeling of off balance
or imbalance, or unsteadiness
when patients are walking.
00:58
When we hear those descriptions,
our approach to the patient is
to look for cerebellar dysfunction.
01:04
And we do that on neurologic exam.
01:06
We're looking for dysmetria,
with finger-to-nose finger testing,
or heel-to-shin testing,
or ataxia
as the patient is sitting
in an upright position,
or walking in ambulatory.
01:18
And those physical exam findings
either on the patient
or in a clinical vignette
point us into needing to evaluate
the cerebellum further.
01:26
And typically,
our diagnostic investigation
will center around
MRI of the brain.
01:31
We may do some other
laboratory testing
and perhaps some genetic testing.
01:35
But our first step is to typically
image the cerebellum.
01:39
The history is told us
that's where our concern is,
the exam is pointed to that system
as the problem,
and our imaging is
going to evaluate that.
01:47
So that's an overview of evaluating
patients with cerebellar problems
and cerebellar circuitry
dysfunction.
01:52
Let's dive into the cerebellum
and understand a little bit more
about what's going on
with these patients.
01:59
When we think about the cerebellum,
most of us think about
its importance in motor,
movement, and coordination.
02:05
The cerebellum modulates
motor movement
and helps us to remain coordinated.
02:11
But it also does a number
of other things.
02:13
It really coordinates everything
that goes on in the brain.
02:16
It coordinates our attention,
helps to coordinate and maintain
coordination of language
and language processing.
02:23
It's important in
learning and memory,
particularly motor memory,
as well as even fear,
and our pleasure responses.
02:30
So the cerebellum has
been called the mini brain
and helps to coordinate
most of those brain functions.
02:38
When we think about
the cerebellum,
there are many problems
that can develop.
02:41
Many diseases that affect
the cerebellum.
02:44
And this table
is an important table
for organizing
all of those conditions
that we can see clinically.
02:50
When I think about
cerebellar pathology
diseases affecting the cerebellum,
I categorize into those
that occur sporadically.
02:59
They're acquired.
03:00
They develop
over thecourse of lifetime,
and those that are inherited.
03:04
The acquired sporadic conditions
can be autoimmune
things like
multiple sclerosis,
systemic lupus
can affect the cerebellum.
03:12
A rare but important condition
called
Neuro-Behçet's and
Sjogren's syndrome
can all affect the cerebellum
and cerebellar circuitry.
03:20
We also see infections
that can affect the cerebellum.
03:22
Things like infectious cerebellitis
or post-infectious cerebellitis,
or even
Creutzfeldt-Jakob Disease (CJD).
03:30
Neoplasms can affect
the cerebellum,
as well as
paraneoplastic conditions.
03:35
And in terms of the
paraneoplastic processes,
we think about certain antibodies
that have a predilection for
cerebellar cells or fibers.
03:43
Anti-Yo, anti-re, and anti-hu
are three paraneoplastic conditions
that are, have a predilection
for the cerebellum.
03:52
We also see congenital
or abnormalities.
03:53
Those things in
pediatrics or in kids
that can affect the cerebellum.
03:57
Chiari malformations,
which is distension
of the cerebellar tonsils,
Joubert disease, and
Dandy-Walker syndrome.
04:05
Environmental toxins and ingestions
can frequently affect
the cerebellum.
04:09
The cerebellum is
metabolically active,
it's working all the time.
04:13
It's coordinating all those
things and functions of the brain.
04:16
And so alcoholism is one
of the most common causes
of cerebellar dysfunction,
as well as gluten enteropathy,
it can affect cerebellar circuitry
and cause ataxia, and dysmetria.
04:26
Many of our antiepileptic drugs
and specifically Dilantin
can cause long term
cerebellar toxic toxicity.
04:34
Nitrous oxide,
and various types of chemotherapy
and cytarabine is the
chemotherapy to think about
that causes dysmetria
and abnormalities
with cerebellar function.
04:45
And then lastly,
we can see degenerative problems
affecting the cerebellum.
04:49
And probably the one
to remember the most
is called multiple system atrophy
of the cerebellar type.
04:54
This is atrophy of
multiple areas of the brain,
but there is a predilection
of cerebellar atrophy.
05:00
And this was formerly called
olivopontocerebellar atrophy,
a degenerative condition.
05:06
So if those are the
acquired conditions
that affect the cerebellum,
we can also think about
inherited cerebellar diseases.
05:12
And we categorize those
based on whether
they're progressive or episodic.
05:16
The progressive conditions
just get worse over time.
05:20
And the episodic conditions
come and go.
05:23
Progressive conditions
are typically inherited,
and they can be inherited in
an autosomal dominant fashion
or autosomal recessive.
05:29
Most of the autosomal dominant
progressive ataxia syndromes
are the spinal cerebellar ataxias.
05:36
And we number them.
05:37
And you don't need to know
all the individual details,
but their spinal cerebellar ataxia
1 to 5, 7...
05:43
up to even over the 30s.
05:45
And each of those present often
with progressive ataxia
with an autosomal
dominant inheritance.
05:51
As well as this rare condition,
which is interesting
dentatorubral-pallidoluysian
atrophy,
or it's just easier to say DRPLA.
06:00
The autosomal recessive cerebellar
conditions are things like
Friedreich's ataxia,
ataxia-telangiectasia,
ataxia with vitamin E deficiency,
and Wilson's disease.
06:11
And again, we can learn
in another lecture about
some of the details
of each of these conditions.
06:16
But it's important to have
an organizational structure
for how to think of these.
06:20
And there are some other conditions
that can cause progressive ataxia.
06:24
The paroxysmal, or episodic ataxias,
we call them the episodic ataxias.
06:29
And there's a number of these
based on the channel
within the cerebellum,
that is dysfunctional
EA 1, 2, 3, and 4,
and those present with
episodes of ataxia,
and in between the episodes,
the patients are typically normal,
or some varying degrees
of abnormality
interactively between
those episodes.
06:48
So, if those are some
of the conditions
that affect the cerebellum,
let's spend the rest of the talk
talking about
what is the cerebellum?
How does it work?
And what are some of the most
common diseases
that we should think about
when there's a problem with the
cerebellum or with disequilibrium?
And I think an important tip
for a place to start
is the cerebellum has been called
the mini brain,
and it's organized
a very similar to the brain.
07:09
And so we can use
our understanding
of how the brain is
structured and organized
to understand how the cerebellum
is structured and organized?
When we think about the brain,
that the most
outer area of the brain
are the lobes, the cerebral lobes,
the area of the cortex.
07:24
We think about the
frontal lobe, parietal lobe,
occipital lobe, and temporal lobes.
07:30
Beneath the lobes
are the white matter,
the subcortical white matter
of the brain.
07:34
And we'll find that the cerebellum
is organized similarly.
07:38
And then beneath the subcortical
white matter, a deep further
is the subcortical
gray matter structures.
07:43
In the brain, that's the
caudate-putamen, and globus pallidus
as well as others
accompanying structures.
07:48
And we'll see we have
similar organization
within the cerebellum.
07:53
So what does that look like
in the cerebellum?
Well, what are the lobes?
The first is the vermis.
07:59
This is that midline lobe,
in the center of the cerebellum
that controls our trunk
in coordination primarily
of the trunk.
08:06
And that's the cerebellar vermis,
one of the important lobes.
08:10
We also see the hemispheres.
The cellar cerebellar hemispheres.
08:13
There's an anterior and a posterior,
and a left and a right hemisphere.
08:18
And that controls
the appendicular function
and appendicular coordination,
our arms and legs.
08:23
The last lobe of the cerebellum
is the smallest
but perhaps
one of the more important
and that's the flocculonodular lobe,
the flocculus and the nodulus,
which come together to control
coordination of eye movements.
08:36
And these are the three lobes
that are involved
in cerebellar function.
08:40
Beneath the lobes
we see the arbor vitae,
that's the name for the subcortical
white matter of the cerebellum.
08:46
And that's going to connect
the cerebellum
to all of the important structures
to the brain and to various places
within the spinal cord.
08:56
And then going deep further,
just as in the cortex,
we had deep subcortical gray matter
in the cerebellum.
09:01
We also see, there is deep
subcortical gray matter structures.
09:05
These are going to be
the output relay for the cerebellum.
09:09
Information will come
into the hemispheres
in the vermis,
and the flocculonodular lobe.
09:13
The cerebellum will work on that
information to coordinate it
and then send that to the deep
subcortical gray matter structures
to be sent back to the brain
and back to the spinal cord,
to coordinate our head,
eye movement, and other functions.