Now, we can move on to perform the testing that assesses the functioning of the cerebellum.
And we're going to first do limb ataxia and then gait ataxia.
So, for limb ataxia, we're trying to see
if the cerebellum is processing all the inputs from the peripheral nervous system
to complete a series of relatively complex task of coordination.
And the most common ones that we start with are the Finger-nose-finger test.
So, what I want you to do is just use your index finger, just touch my finger actually.
Now, you can touch your nose and just keep following my finger in that way
with your finger as I move it around in space.
Back to your nose, back to my finger, back to your nose, back to my finger.
Keep in mind that I'm actually keeping my finger far enough away that he has to fully extend his arm.
You don't want to just do it right in front of his face
because you're not really getting the full activation of his cerebellum.
Having to really pinpoint something in three-dimensional space with his - with using coordination.
So, that's Finger-nose-finger, that's testing cerebellar function in particular the upper extremities.
Now, we'll do Heel-to-shin.
What I'd like you to do is to basically take the heel of one foot
and I want you to bring it up to your knee and then back down again,
right in front of your shin, just like that.
Great. And then just do it on the other side. Perfect.
You of course always looking for a symmetry.
Patients who have cerebellar functions when they do Finger-nose-finger,
they have a lot of trouble with grossly trying to figure out where their finger is supposed to be in space.
In contrast to a person who just has a tremor will have regular amplitude deviations from the course
but there's still at least heading in the right direction even if it's a -
you know, waxing and waning as they get to their - to the target.
Next step we'll do, what's called dysdiadochokinesia
and it's basically just to assess whether the cerebellum can process
rapidly different tests of pronation and supination or flexion and extension in one muscle group.
What I'm going to do is have you have your hands on your thighs and just quickly turn them over just like that.
Great. And patients with either an extrapyramidal problem or cerebellar problem will have problems doing that.
Next, when you test for rapid alternating movements. I just want you to do this for me really fast.
Typically, want to get at least ten of them in a row, make sure they're big and fast
and that's your best way to assess cerebellar function in that sense.
Alright. So, now having assess limb ataxia, we're going to go ahead and asses gait ataxia.
So, Shaun if you wouldn't mind just walking towards me.
Great. And then turn around and walk back the other way.
Now, his gait is perfectly normal, patients can manifest with the variety of different types of walking
depending upon the type of problem or lesion that they have.
Whether it's cerebellar ataxia, sensory ataxia, Parkinson's disease, etc.
I will just demonstrate the gait of a Parkinson's patient because it's a common one that's worth looking for.
This patient have a so-called shuffling gait, to kind of walk like this, short steps.
They'll have a festinating gait which is where they lean forward
and then they have to try to catch up with their feet,
and also, you'll notice that when Shaun turned, he had no problem just quickly turning around,
whereas patients with Parkinson's, when they get to a place where they need to turn,
they have a lot of trouble making turns in space.
They also even can get stuck walking under a door threshold
because of a variety of these kinds of manifestations of Parkinson's
that you can detect by simply walking - watching somebody walk for short distance.
And the last test that we often use when we're assessing problems with ataxia is called the Romberg test.
And I want to highlight here that the Romberg test is actually not testing the cerebellum,
it's testing the peripheral inputs specifically the spinal cerebellar tracts
that are going up to the brain and are being processed or interpreted by the cerebellum.
Patient who have problems with the spinal cerebellar tracts
due to whatever problem with potentially a polyneuropathy,
are not getting input from the muscles and tendons in their limbs
telling them about where their joints are in space,
so when you close your eyes, it's really hard to know if you're falling off balance or not.
So, what I want to have you do is step forward a few steps or a few inches
and I just want you to close your eyes.
A patient who has problems with the spinal cerebellar tracts
or any kind of peripheral problem with sensory integration,
is going to start to move around back and forth, or having trouble keeping their balance.
We typically do this for up to 60 seconds.
Patients with a sensory cause of their ataxia
are going to start to waddle around after probably 10 seconds or so,
whereas somebody with the cerebellar problem,
who doesn't actually have to coordinate any movements in this position,
should be okay with this, they may have trouble after 30 second or so,
but they shouldn't have any problems in the same way that a person with a peripheral problem might have.
You can accentuate this finding by pushing on the patient and see if they're able to maintain their posture.
Now, we'll move on to the assessment of tremor which is also a very common complaint
amongst the patients who present to a doctor's office.
Tremors can be broken up into two different categories.
We have resting tremors and then we have action tremors.
And then action tremors have two different subtypes, we have postural and intention.
So, let's first look at our resting tremor.
Typically, a patient is sitting at rest and you can even distract them
by having them maybe tap their foot or do some other sort of activity
but you're watching their hands.
A patient with Parkinson's disease or Parkinsonism more generally,
will start to have a little bit of vibration in their hand.
Sometimes it's even a little pill-rolling type activity
where their thumb and their finger are moving together.
And as soon as I have them lift up their hands,
the tremor completely disappears so it's exclusively present at rest.
In contrast, a person with an action tremor may have issues with posture,
maintaining a posture or during an intention activity.
So, what I'd like you to do now is put your hands out straight in front of you.
This is a test for a postural tremor.
It's extremely common to have a postural tremor, so called benign essential tremor.
And as people get older, it tends to come out a bit more.
If you drink a lot of caffeine, it's going to come out a bit more.
In a contrast you can treat it with taking a beta blocker,
that sort of thing to cool down that increased sympathetic tone that's causing it.
If you're trying to accentuate a postural tremor,
you can put a piece of paper on a person's hand
because it will kind of quiver, if somebody has a significant tremor.
You're looking for a symmetry that can be helpful as well in the diagnosis.
And then lastly, you can put your hands down now.
We're going to see if the patient has an intention tremor.
We've already kind of asses that when we we're doing the Finger-nose-finger test.
Patients with purely an essential tremor, like again a benign essential tremor
will vacillate and oscillate as they head towards the target
but they will eventually get there and they'll be heading in the right direction.
Whereas with the cerebellar problem which is,
what you're really picking up with an intention tremor is widely wrong inaccurate excursions
as they're moving their hand around trying to get to the target.
So that will be characteristic of an intention tremor often times related to a cerebellar problem.
So, a patient who has a subtle or small hemispheric stroke,
you may not detect any strength or weakness problems but they may have a positive pronator drift.
So, what I'm going to have you to do is put your hands out straight out in front of you
like you're carrying a big pizza with your thumbs out as much as you can.
And now, I want you to close your eyes.
A patient with a pronator drift will start to have this arm will fall and pronate,
exactly like you see him doing there. It may take 30 seconds, it may take a minute.
You can relax now. But that finding of a pronator drift is highly specific for a hemispheric stroke
and again, it's subtle enough that you wouldn't pick it up by just doing strength testing.
And the second one which is even better in terms of predicting a hemispheric stroke
or any kind of hemispheric lesion honestly,
even a tumor would do this is called the Forearm Rolling test.
And I want you to basically roll your forearm like you are a boxer.
Exactly, and he's perfectly symmetric in terms of one arm and the other arm are moving evenly.
In contrast if a person has a left hemispheric stroke,
you may find that he starts to preferentially have one turn but not the other.
And that's something which - since there's so many muscle groups involve in regulating this activity
that loss of any part of a motor strip could manifest with that subtle distinction
and that is a very useful sign with a high likely ratio for hemispheric stroke.