Transcript DBS Full Storyboard - Illinois State University

DBS Full Storyboard
Slide 1
• Just to introduce a sort of story format, I think
it would be cool to have the first part of the
DBS lab to be a set of doors like in the
Parkinson’s Lab. The student will click the door
to enter and will proceed to the next slide. If
this is not feasible, going straight into
Slide 2
Welcome to the Deep Brain Stimulation clinic!
My name is Dr. Rita Smith. I understand that
you are an up and coming medical student
looking to become a neuroscientist! Well, you
came to the right place. Today, I will be teaching
you the basics behind a surgical procedure
called Deep Brain Stimulation. Once you have
mastered the information, you will assist me in
performing surgery on a patient. Let’s get
started!
Slide 3
The patient coming in today is
named James Johnson. He
suffers from a neurological
disorder known as essential
tremor that results in his hands
shaking against his will. James’s
works as a weather forecaster
with a major news television
station. James’s hand tremoring
has gotten so bad that he is
close to losing his job as people
focus more on his uncontrollable
hand shaking than the news.
Let’s go meet James and do
some preliminary testing.
Hello James, I am Dr. Rita
Smith. I will be the
primary surgeon working
with you. The student I
have with me will be
helping me with the
surgery after extensive
training. Could you draw a
circle on this paper to
demonstrate the severity
of your essential tremor?
After the deep brain
stimulation surgery, we
will have you sign your
name again for
comparison purposes.
As you can see, James’ hand tremoring is so bad
that he can barely draw a circle! Thank you
James’, see you at the surgery! Alright, let’s head
to the lecture room to review essential tremor.
“Let’s go over some basics. James’
suffers from essential tremor. In effect,
there a serious of neurons in his brain
that are haywire. To review neurons,
read through this module:
http://www.mind.ilstu.edu/curriculum
/neurons_intro/neurons_intro.php?m
odGUI=232&compGUI=1826&itemGUI
=3155
(If you think this is possible, David, we
could insert the whole Mind Ilstu
Neuron page into this module just to
make the students go through it fully)
“A neuron (nerve cell) is the basic unit of
the brain and spinal cord. Neurons are
responsible for your senses of sight, smell,
taste, hearing, and touch. Neurons are
responsible for making you happy when
you ace a test, sad when you leave those
you love, and excited before a basketball
game! However, damage to neurons
results in a whole variety of disorders that
relate to movement, the senses, and
emotional distress. Defective neurons
lead to mental disorders like obsessive
compulsive disorder, depression, or
schizophrenia. Defective neurons can also
lead to motor disorders like James’
essential tremor.”
Great, now that you are familiar with
neurons and how they interact in the
brain, let’s return to James’ case.
Essential tremor has been linked to the
loss of neurons in a region of the brain
called the Cerebellum. These neurons
are specifically known as Purkinje cells.
In addition to loss of cells in the
cerebellum, build up of protein within
neurons located inside the pons has
also been associated with causing
essential tremor.
These disrupted neurons are
unable to effectively
communicate with neighboring
neurons. Thus, electrical
communication is broken down in
essential parts of the brain
responsible for normal function.
In this sense, signals sent from the
brain to muscles throughout the
body act unusually.
Essential tremor is normally
treated with medication in an
attempt to restore lost
communication between neurons.
When essential tremor stops
responding to medication,
patients often begin seeking more
serious measures to deal with
their essential tremor. One of the
newer techniques used to treat
essential tremor is known as deep
brain stimulation.
Deep brain stimulation, or DBS, is a
surgical procedure where a device
capable of electrically stimulation is
lowered into the brain. This device,
known as an electrode, is turned on by a
battery pack that is inserted into the
patients chest. When the electrode is
turned on, it sends electrical pulses
through the brain that ideally restore
broken down electrical communication
between neurons.
The electrode may be lowered into
different parts of the brain to treat
different diseases and disorders. Many
neurologically based disorders stem from
abnormally electrical activity. Therefore,
electrical stimulation of different parts of
the brain can lead to treatment of a
variety of disorders including Parkinson’s
disease, Tourette’s syndrome, Obsessive
compulsive disorder, and even obesity.
These next three slides show the
implantation of the DBS electrode
into different areas of the brain
leading to different outcomes.
Parkinson’s, obesity, and chronic
pain.
These next three slides show the
implantation of the DBS electrode
into different areas of the brain
leading to different outcomes.
Parkinson’s, obesity, and chronic
pain.
These next three slides show the
implantation of the DBS electrode
into different areas of the brain
leading to different outcomes.
Parkinson’s, obesity, and chronic
pain.
Despite the enormous benefit of DBS,
much of its mechanism remains unknown.
In fact, when the electrode is merely
lowered into the patient’s brain without
electrical stimulation, the patient’s
tremoring may stop. This phenomenon is
known as the Honeymoon effect and
suggests that deep brain stimulation has
many different effects on the human brain.
Therefore, it is essential that more research
is done on deep brain stimulation to fully
understand how it works.
Before we perform deep brain
stimulation surgery on James, I want to
take you through a surgery performed
on a patient at the Mayo Clinic. You will
be watching a serious of videos of an
actual DBS surgery performed by Dr.
Kendall Lee on a patient with essential
tremor. Let’s start off with the
introduction.
In this video, a patient is questioned about
how and why he chose deep brain
stimulation for treatment of his essential
tremor.
The patient first experienced essential
tremor as a teenager when he was trying
to sauder wires in a stereo. The patient
mentions how hard it is to go through life
with essential tremor. For example, he
cannot shave well or type on a keyboard.
In this video, you will see the mounting of a head frame. The
purpose of the head frame provides a coordinate system that
will be used when looking at MRI images taken of his brain.
You will see the patient have local anesthesia injections to the
skin on his head so that the head frame can be properly
mounted.
At the end of the video, you will see a localizer box put over
the head frame.
This next video shows the MRI images
taken of the patients brain. As you will
see, the localizer box that was attached
via the head frame provides coordinates
that aids the surgeon to find the tremor
cells. Take a look at the image below.
The dots on the side of the head arise
due to the localizer box.
You will also hear Dr. Kendall Lee point
out the location of the tremor cells in
the MRI images.
These images provide Dr. Kendall Lee with a great idea of where
the target tremor cells are for electrical stimulation. Equally
importantly, Dr. Lee mentioned that the MRI provides an idea to
where blood vessels are located. Note the white dots scattered
throughout this image. These are each blood vessels. If a blood
vessel is hit during surgery, the patient may have a stroke and die.
The next video demonstrates how the
MRI images taken of the patient’s
brain are used to plan out the surgery.
In other words, where exactly the
tremor cells are in the brain. The
target area in this surgery for
stimulation with the DBS electrode is
the VIM thalamus.
As you head from Dr. Lee, there are
many different variables involved in
mapping the exact trajectory of the
electrode. These variables take into
account blood vessel avoidance and
location of the tremor cells. Once this
trajectory is mapped out, the electrode
will be positioned in such a way that the
electrode perfectly reaches its target, in
this case, the VIM thalamus.
Pay close attention to this video. Since the
electrode will be lowered over the top of the
head, a pathway must be planned so that
the electrode reaches its destination
without damage to the brain.
Dr. Lee highlights some of the blood vessels
and adjusts the electrode, represented by
the red line, so that the electrode misses all
of them but still reaches tremor cells in the
VIM thalamus.
As Dr. Lee mentioned, the most
important part of the surgery lies in the
mapping of the electrodes trajectory.
The number one priority of surgery is to
avoid hitting a blood vessel with the
electrode that could result in death of
the patient.
This next video introduces some of the
instruments used in the DBS surgery.
Dr. Kendall Lee starts by showing the X-Ray
tube that allows images to be viewed of the
brain while the DBS electrode is lowered
into the brain. This is important just to
make sure that the electrode is being
lowered at the right trajectory.
Also, take note of the electrophysilogy rig
described by Dr. Lee. After you watch the
video, I will talk more about its purpose.
The purpose of the electrophisiolgy
rig is of upmost importance. Since
region of the brain being sought is
small, it is hard to know when it has
been reached by the electrode.
Although prelimarnry mapping was
done using MRI images, it is hard to
locate the exact location of the
neurons. Thus, the
electrophysiology rig is used. As the
electrode is slowly lowered into the
brain, the tip of the electrode
records neuron activity. Once the
electrode reaches the tremor cells
in the VIM thalamus, the monitor on
the electrophysiolgy rig will show
haywire cell firing, indicating that
the electrode is located exactly at
the tremor cells.
The next set of videos marks the
beginning of the surgery itself.
First, the patient is submitted to a
tremor test. This is similar to the
tremor test we performed on
James earlier. At the end of the
surgery, Dr. Kendall Lee will ask
the patient to once again do the
tremor test to the effectiveness of
the DBS surgery.
This next video shows several of the
first steps of the surgery.
The first thing Dr. Lee will do is shave
the patients head. Later, you will see
the patient have a hole born into his
skull, where the electrode will be
lowered. Hair may get in the way and
it is essential to remove it.
Next, you will see the patient have his
scrubbed to ensure sterilization. This is
a critical part to any surgery as it
reduces chances for bacterial
infection.
This next video begins with Dr. Lee preparing
the drill. The patient is covered with a tarp
with only his head exposed. Dr. Lee then
prepares to check the angles from which the
electrode will be lowered at in accordance
with the trajectory plan mapped earlier. It is
imperative that all the angles are exactly
right to make sure a blood vessel is not hit
when the electrode is lowered.
Next Dr. Lee makes an incision where the
electrode is to be lowered and drills a hole
into the skull. During this procedure, the
patient is awake with only local anesthesia
in the area where a hole is drilled into the
skull. Once again, Dr. Lee double checks the
angles throughout the drilling process.
In this video, Dr. Lee uses a tool to break through the dura
mater over the drilled hole. The dura mater is a tough
membrane right beneath the skull and covering the brain.
This must be broken or else it will deflect the electrode.
This next video starts directly with the lowering of an electrode into the brain
of the patient. The patient is awake throughout this whole process because
there are no pain receptors in the human brain.
The electrode that will be lowered first into the brain is used to locate the
tremor cells. As I mentioned earlier, it is imperative to find the exact location
of the tremor cells to a degree that cannot be accomplished merely through
MRI imaging. This is done by lowering a test electrode into the brain that
records neuron firing. The test electrode is not capable of electrical
stimulation, but can read electrical signals throughout the brain. As the
electrode is lowered past normal cells and then to the tremor cells, the
electrophysiology rig will show abnormal peaks indicating that the tremor
cells have been found.
Dr. Lee also has the patient do tremor tests throughout the lowering of the
test electrode. Dr Lee will mention a phenomenon known as the
microthalotomy effect where just the placing of the electrode, without
electrical stimulation, into the malfunctioning brain area will lead to reduced
tremor.
In this next video you will see Dr. Lee first remove the testing microelectrode
from the patients brain. Then, Dr. Lee will put in the DBS electrode capable of
electrically stimulating the tremor cells.
Note that Dr. Lee will mention that as the DBS electrode is lowered into the
brain, the patient may feel numbness at the corner of his mouth. This is a
good sign because it means that the DBS electrode is hitting the right place.
Throughout the lowering of the DBS electrode, Dr. Lee will have the patient
do tremor tests on pen and paper. Pay close attention to these tests.
In the last video, you saw Dr. Lee implant the DBS electrodes so that they can directly
stimulate the tremor cells. In this next clip, you will see surgeons implanting the battery
pack under the patient's chest. This battery back will connect to the DBS electrodes via
wires under the skin, and will provide the voltage needed to electrically stimulate the
tremor cells.
You will see Dr. Lee create a tunnel under the patients skin so that the battery can
connect to the DBS electrodes under the skin.
This clip may bother you if you are sensitive to small amounts of blood.
Two videos ago, you heard Dr. Lee mention that the patient's tremor went
down when the DBS electrode was merely lowered into the brain. This
phenomenon, known as the microthalotomy effect, is only apparent for a
short while. If the tremor comes back in a few days, then Dr. Lee will begin
programming the DBS electrode to stimulate the tremor cells in the patients
day.
To wrap up the surgery, Dr. Lee discusses the future of DBS. Dr. Lee will
mention various disorders capable of being treated by DBS. Electrical
stimulation of completely different parts of the brain can yield different
benefits.
Dr. Lee will will discuss how DBS can be used to control brain communication in
a very detailed manner. Dr. Lee will mention how DBS, a form a
neuromodulation, can be used to treat a whole variety of disorders and
diseases.
Let's review quickly. First, the stereotaxic head frame was put onto
the patient's head. Local anesthesia was injected where the screws
secure the head frame to his skull. Then, a localizer box was put on
the head frame that served a role in mapping out a coordinate
system which could easily locate different areas of the brain. The
patient's brain had MRI images taken of it to locate the blood vessels
and also to plan a trajectory that the electrode will be lowered.
Next, the information gathered from the MRI was put into a
computer system to find at what angles the electrode should be
lowered at to avoid hitting any blood vessels that could cause a
stroke and also reach the desired tremor cells.
Once the trajectory was found, the skull was shaved and sterilized, a
hole was drilled into the skull at which the electrode was to be
lowered. A testing electrode was slowly lowered into the brain that
could measure electrical signals of the cells. Once the testing
electrode was lowered far enough, it began showing abnormal cell
firing on a monitor which indicated that the electrode had reached
the desired tremor cells responsible for the patient's essential
tremor. Then, the testing electrode was replaced with a DBS
electrode capable of electrically stimulating the tremor cells.