Spinal Cord Screening Exam
The last major section in the evaluation for a central nervous system lesion
is evaluating the spinal cord.
Evaluation of the integrity of the spinal cord
requires evaluating the descending spinal tracts
or motor pathways
and the ascending spinal tracts
or sensory pathways.
There are essentially two descending tracts which a clinician should be familiar with.
The first is the corticospinal or pyramidal tract
and the second is the extrapyramidal.
Lesions of either of these two tracts produce an upper motor neuron lesion,
and present with the signs
discussed previously in this tape.
Let's talk about
how to evaluate the corticospinal tract.
This is done by performing
the pathological reflexes.
First, the Babinski reflex
or the plantar stimulation reflex.
And secondly, the Hoffmann reflex.
The way we evaluate for the Babinski reflex
is by taking our Taylor hammer
or a blunt instrument,
raising the leg, and stroking the heel of the foot
towards the ball of the foot in a circular fashion.
Let's do it one more time.
We start at the heel along the lateral foot,
stroking towards the center of the foot,
ball of foot.
And do you see how the toes curl?
That means the toes are down
going to plantar stimulation
which is a normal reflex.
Let's do the other side.
Start with the heel,
push hard across the lateral
and towards the ball of foot.
Do you see the toes curl?
That’s a normal Babinski reflex.
The abnormal plantar stimulation reflex
or Babinski reflex
would be extensor of the hallucis longus
and fanning of the other toes,
so the extensor muscle would contract
bringing up the big toe.
The second pathological reflex that is checked for evaluating for pyramidal tract lesion
is the Hoffman.
Hoffman is checked by flicking the middle finger
of the hand with your thumb
and looking for a pincer activity
of the thumb and index finger.
If the thumb and index finger twitch together,
that’s an abnormal response and indicates a pyramidal tract lesion
primarily isolated in the cervical spine area.
Let's do it one more time.
Just flick the middle finger.
And as you can see, there’s no activity here of the thumb and the index finger.
If they come together, that’s an abnormal finding
indicating a pyramidal tract lesion within the cervical spine.
Now let's look at the ascending tracts
of the spinal cord.
There are primarily two ascending or sensory tracts which the clinician should be familiar with.
These tracts include the spinothalamic tract
which includes the lateral and ventral portion
and the posterior columns.
In evaluating the lateral spinothalamic tract, we’re looking for sensations of pain and temperature.
Pain is evaluated by pricking the patient with a pin
and see if it hurts.
So we’re going to check this patient for pain.
Dr. Conwell: Do you feel that? Deb: Yes.
Dr. Conwell: Feels good and sharp? Deb: Yes.
Dr. Conwell: You don’t like that? Deb: I don’t like it.
Dr. Conwell: Okay.
Or we could check by checking the patient’s response to hot or cold
or we’d put hot water or cold water in a test tube and apply it to the patient’s skin,
and see if they felt it.
The ventral spinothalamic tract carries the sensation of light touch.
Again, light touch can be performed by rubbing the back of the fingers across the hand,
asking the patient if they feel it. Deb: Yes.
We should never use the palmar surface of the hands, because we’ll stroke too strongly
or we can use our friendly troll,
and stroke to see if the patient feels this.
Do you feel this? Deb: Yes.
As we discussed earlier, other ways of checking for light touch
is by taking the tip of a cotton swab
and checking for light touch in that manner,
or using a ball of cotton, pulling it off,
so we’ve got some cotton fibers checking for light touch this way.
So we are checking for sensation of light touch
or transmission of this light touch
through the ventral spinothalamic tract.
The other ascending tract we want to evaluate is the posterior columns.
The posterior columns are the fasciculus gracilis and fasciculus cuneatus.
The posterior columns transmit the sensations of vibration, deep pressure, position sense,
two-point discrimination, and warm and cool.
Let's talk about proprioception or position sense.
In evaluating for position sense,
we can start with the foot.
We put our fingers on the side of the joints instead of on the top.
And we ask the patient to close their eyes and tell us where the toe is in space.
Now I’m going to move the toe down,
and ask the patient and say, “Where is this toe in space”?
Deb: Down. Dr. Conwell: Down.
Now I’m going to move it again
and see what they say.
Now let's look at vibration.
Vibration is carried in the posterior columns.
And we check vibration -- We use C-128 vibration tuning fork.
We ask the patient to lie down, face up with your head here and your feet down here.
And we essentially check three areas.
We check the medial malleolus, the ASIS,
and the clavicle.
Now I start with the medial malleolus
and ask the patient to close her eyes,
and --
Dr. Conwell: Do you feel this? Deb: Yes.
Let's do it on the other side.
Do you feel this? Deb: Yes.
Now if they feel this, you don’t need to go to the ASIS or the clavicle
because we’ve checked the projection all the way up the spine.
If they cannot feel it over the medial malleolus,
we’re going to check it over the ASIS or anterior superior iliac spine.
Dr. Conwell: Do you feel this? Deb: Yes.
Dr Conwell: And do you feel this? Deb: Yes.
Now let's do the clavicle.
Dr Conwell: Do you feel this? Deb: Yes.
Dr Conwell: And here? Deb: Yes.
Now what we’ve checked ...
Will you stand up for me please, Deb?
... is vibration or projection of vibration through the posterior columns.
Now I want to check two-point discrimination.
In two-point discrimination, we’re determining how far or how close the patient can feel
two objects placed on the skin at the same time.
So, we’re going to turn the palm up.
And I’m going to place this on your palm
and you tell me if you feel one or two points being placed on you, all right?
Close your eyes, please.
Dr Conwell: Now tell me, Deb.
Do you feel one or two? Deb: One.
Now, see. I’m doing one first to make sure the patient gives me a proper response.
Now we’re going to try two and see what happens.
Dr. Conwell: Do you feel that? Deb: Yes.
Dr. Conwell: One or two? Deb: Two.
And I’m going to keep going closer.
Dr. Conwell: Do you feel that? Deb: Yes.
Dr Conwell: One or two? Deb: One.
Dr. Conwell: One.
Now, I’ve got two on her hand.
I’m going to measure that and see if it’s within normal limits or not.
We have covered a lot of steps
in evaluating the descending and ascending tracts of the spinal cord.
A quick screening procedure would be to perform Babinski or plantar stimulation,
and also pin prick for lateral spinothalamic tract and light touch for ventral spinothalamic tract.
If you choose to do the other neurological testing, it would be indicated in your
history portion.
But to screen,
I think all you need to do is perform plantar stimulation, and light touch, and pin prick.