00:00
Alright so guys we've finished our assessment of strength and again weakness could be
found in upper motor neuron and lower motor neuron issue so it's not particularly helpful
in that regard other than characterizing the severity of somebody's weakness. The real
deciding factor is going to be the result of reflex testing. So, as a route to jump into reflex
testing, it's good to orient ourselves to our tools and so let's take a look here. This is
probably the most common reflex hammer that I see used by many medical students and
health practitioner students of various types. This is known as a Taylor hammer and it's
lightweight, it's small, it's easy to carry around, and to be frank I hate it. It's my least
favorite kind of hammer. It doesn't have enough weight to it to really get good reflexes.
00:45
That being said in a pinch, like I said, it's really easy to carry around, it's nice to have with
you. In contrast, this is a Tromner hammer, it's got a lot more weight to it, a lot more
give when you're really applying it to the tendons and most importantly it's not as hard
on the tip so you can really bang on your fingers without, you know, ultimately causing
yourself discomfort. So I find the Tromner hammer to be very useful to have around.
01:09
Sometimes they also come with the ability to test pinprick or the ability to test light touch
as well on the back of the hammer. Okay, so with that, let's jump into reflex testing.
01:26
So just as we wanted to know which muscle groups were associated with which nerve
roots, we also want to know which nerve roots are associated with which reflexes.
01:35
So, the first reflex we're going to look at is C5. Just like C5 controlled biceps strength,
it also controls the deep tendon reflex of the biceps tendon and so I'm going to put my
finger on the tendon here and I can feel that very palpable cord of the biceps tendon and
then I'm going to apply a swing as follows. When we think about the strength of the reflex,
there's a range that we have from 0-4. The normal range is typically 2 and 3. So 2 being
the lower end of normal and 3 being the upper end of normal. That being said, a 1 out of 4
reflex is also quite normal particularly if it's the same on the other side. In contrast,
a 4 out of 4 reflex is hyperreflexia whether or not it's associated with clonus and then
a 0 out of 4 reflex is essentially a mute reflex. Now as you might imagine, a patient who
has a lower motor neuron problem and is not getting any input to that muscle, you're
going to have a 0 out of 4 reflex or certainly an attenuated one. In contrast, if it's an
upper motor neuron problem with the lower motor neuron firing with reckless abandon
without any inhibition, you're going to have hyperreflexia and more leaning towards the
3 or 4 out of 4 on the spectrum. So again, this is the biceps tendon reflex and I'm applying
a good swing to my hammer. It's really to make sure I'm getting the full weight of my
reflex hammer at C5. Now I moved down to the brachioradialis muscle. I'm going to palpate
on the belly of the brachioradialis muscle here which is going to insert on to the radial
styloid. And there's just a subtle bit of pronation that you could see as his wrist curved
inward. You can tilt the hand, the wrist out a little bit more and then you might see a little
bit more of that pronation happening. That was C6. Next, we'll do C7, which is the triceps
reflex and there's a lot of different ways to do this depending upon what position the
patient might be in. I find it's really easy to just actually hold the forearm and hit the
triceps muscle in this way. By doing that, I'm getting contraction of the base of his triceps
which I can actually even feel in my forearm here. Other times I see people try and "relax
your arm" come around the patient which is certainly a reasonable thing to do. It depends
how uncomfortable it is for the patient and whether it's convenient for you but you can
also do it like this and I'll get the same result which you can see as his hand moves out
towards the side. So that was C5, C6, C7, very straightforward. And now moving on to the
lower extremities. There are 2 reflexes we're going to look for down there. Since this
was L2 for strength, this is L3 which is going to be a significant portion of the knee jerk
deep tendon reflex or quadriceps reflex. I usually palpate where the tibial tuberosity is
and I know that I'm going to go right above the tibial tuberosity as such. Great. So that,
I would say is a 3 out of 4 reflex on the right and comparing with the left. Those are about
the same depending about the strength of my hammer. So, as you can see he may have
had a 1 to 2 out of 4 reflex up in his biceps, but as long as that's symmetric up there and
even if it's a little bit higher downstream that's okay. It's really when you're looking for
asymmetry that would be more concerning. So the next deep tendon reflex in the lower
extremity is the ankle reflex and this is going to be L5-S1, which is involved in the
plantarflexion of the foot. I'm going to basically put his ankle at approximately 90 degrees
of dorsiflexion. I'm going to hit a few centimeters above the calcaneus. And you can see
a nice downward plantarflexion there in his right foot. In some instances, it can be difficult
to wrap around to tap on the Achilles tendon particularly in a bedbound patient so we
can actually do this maneuver simply by putting your hand underneath the patient's foot
and hitting on your feet as shown here. I'm getting just as much of a response with this
approach as I would by trying to find and hit the tendon. So, sometimes you may come
across a patient who appears to have no evidence of reflexes particularly in the lower
extremities and we said those are mute reflexes. If you really want to bring out those
reflexes because particularly in elderly patients they can be very subtle. There is a trick
called the Jendrassik maneuver which helps to accentuate those lower extremity reflexes.
06:23
This is an effort to trying to distract the descending input from the cortex from inhibiting
the action of this spinal reflex. "So what I'm going to have you do Sean is I just want you
to put your fingers together like this. And then I'm going to again check your knee reflex"
while he is pulling his hands apart. "And I don't want you to pull your hands apart until
we're ready to go." "So now, go ahead and pull your hands apart." And he already had a
robust reflex but simply doing that Jendrassik maneuver "and you can relax." Further
exaggerates that maneuver whether you're looking at the knee jerk reflexes or the ankle
jerk reflexes. That can be a useful way to augment those reflexes. I've seen even some
neurologist will not only have the patient do this Jendrassik maneuver but also have their
head turn from side to side while they're doing it. And if that doesn't bring out the reflex
in the lower extremities, then nothing will. The last test looking for upper motor neuron
dysfunction is to perform the plantar reflex also known as the extensor reflex also known
as the Babinski and all we're going to do is apply some in a hockey stick maneuver and
simply go in that kind of slow approach. It should take a few seconds to fully navigate
around the sole of the foot and you're looking for, in abnormal circumstance he would
have his feet, his toes would flare upwards like this. Whereas as you saw in his case,
all he did was his toes sort of plantarflexed a bit, which is completely normal.