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- I'm taking a couple of weeks off and while I'm gone,
some brilliant people are standing in for me here.
First is Alex from Brainbook, he's a brain surgeon.
There's nothing gruesome in this video,
but there is the answer to a question I never knew I had,
how do neurosurgeons find their way around inside the brain?
- Neurosurgery is fraught with risk.
The brain is packed with almost 100 billion neurons
compartmentalised into complex bundles of nerves
and other structures that make you who you are.
Small parts of your brain are vital for allowing you
to speak, move, think, learn and love.
As neurosurgeons, we operate in and around
these vital structures and spend a great deal of time
learning the anatomy so that we can operate safely.
The room for error can be millimetres
as we manoeuvre around blood vessels and critical nerves
and damaging any of these can cause either life changing
or life ending complications.
No matter how good the surgeon and no matter
how good their knowledge, we can still go astray
and need a helping hand.
Neurosurgery is a specialty that's inherently
intertwined with cutting edge technology,
and we can use that to guide us
when we're navigating the brain.
Today I'm going to show you how neurosurgeons
can use infrared and electromagnetic image guidance systems
to show us exactly where we are in the brain
during critical operations like brain tumour surgery,
or inserting biopsy needles deep into the brain.
This is a Medtronic StealthStation S8.
It's a combination of hardware and software
that uses special trackable instruments,
such as this pointer and this stilette.
To be able to guide the neurosurgeon,
the system tracks the position of these instruments
in relation to the surgical anatomy
and sends that information to the software.
The software then displays the instrument's position
on either the CT or MRI scan of that patient.
The system can track instruments either optically
using an infrared camera or electromagnetically.
With optical tracking, this camera sends out
and then detects infrared light
that's reflected from these silver balls.
The camera then transmits the instrument's location
to the navigation software.
Similarly, with electromagnetic tracking,
the emitter emits a low energy magnetic field
with unique characteristics at every point.
The electromagnetic instruments contain sensors,
which allow the navigation software
to identify the instrument's location within the electromagnetic field.
For the software to display the instrument's location
in relation to images of the patient, you've got
to help the software by creating a map
between points on the patient and points in the images.
This process is called registration,
and it's essentially the same for both optical
and electromagnetic types.
After registration is complete, whenever the surgeon
touches a point on the patient using one of these tracked instruments,
the computer uses the map
to identify the corresponding point on the images.
This identification is called navigation.
And now I'm going to show you both systems in action.
Here we've got an MRI scan of a brain model
that we're going to use.
Coming up, you see this white blob, which is supposed
to be a simulated brain tumour on the MRI scan.
Up here, you can see an eye coming into view,
and then the nose.
So this is the brain that's going to correspond with the model.
In the bottom right hand corner, we're using infrared tools,
and you can see the pointer coming into reference
with the reference array that we've got fixed
to the patient's head.
We're going to be doing registration as we mentioned before,
marking out lots of points with the infrared pointer.
Now we can verify the registration.
We've got 1.5 millimetre accuracy,
which will do for this simulation.
So, we're going to touch the tip of the nose on the model
and you can see in the MRI that that correlates well.
Let's look at the inner part of the eye and that looks good.
The outer part of the eye and the tip of the ear,
and this is all looking like
it's corresponding really nicely.
We put the pointer into this hole that's pre made,
we're on the tumour, so that's looking good as well.
And this is a pre made craniotomy or trapdoor in the skull
that's going to allow us to just access the tumour straight away.
In real life, we'd make this hole
and that would take about 45 minutes to an hour,
having cut through the skin and drilled off this bone.
So we can operate around this tumour and see exactly
where we are in the brain avoiding critical structures
like blood vessels, nerves and parts of the brain
that are important for speaking and seeing, for example.
Now let's move on to the electromagnetic form of navigation,
which is also called axiom guidance.
We're going to be using a Rowena neurosurgical simulator
and thanks a lot to Susie Glover from Delta
and Stephanie Brown from NHS Healthcare Horizons.
This model is quite cool because it actually has fluid systems within it
and here you can see us actually scanning it
and we're going to take these CT images and plug them into the software.
Here you can see we've put the model in pins,
but we don't usually do that because it can interfere
with the electromagnetic system.
We're going to be using this stilette to guide
a piece of tubing deep into the brain's fluid reservoirs.
This pointer is what we're going to use to do a registration.
This is the actual catheter that we're going to be inserting
deep into the brain and we'll take out
the little metal stilette that comes with it,
and insert the tracked axiom stilette
that comes with the electromagnetic system.
So now that catheter is tracked, we can use this pointer
to mark out exactly what trajectory we're going to be using
and see where we're going to need to make a cut
and then later on where we're going to make a burr hole
which is a small hole in the skull
that allows us to access the brain.
Now we're going to mark it with a red marker in this case
and start drilling.
[high speed drilling]
Once we've made the hole and done a bit more work
in real life, we're ready to put the catheter in.
On the right so you can see that the StealthStation
is showing us how far we need to go and shows us a target
that we've pre-planned.
We're going to follow that trajectory
and make sure the green dots line up.
As we advance the catheter down,
it gives us a countdown in millimetres.
Once we reach zero, we should be in the ventricle system
and as I take out the metal stilette from inside the tubing,
fluid should start coming out.
And there we are, we are in. And in real life
we'd now secure this catheter and get out of there.
- Go and subscribe to Brainbook, start with his video
on a day in the life of a neurosurgeon on call.
Next week, we go from brain surgery to settling on Mars.