Reflex Testing

by Stephen Holt, MD, MS

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    00:01 Alright, so guys we've finished our assessment of strength and again weakness could be found in the 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.

    00:15 The real deciding factor is going to be the result of reflex testing.

    00:19 So as we're about to jump into reflex testing, it's good to orient ourselves to our tools and so let's take a look here.

    00:26 This is probably the most common reflect hammer that I see used by many medical students and health practitioner students of various types.

    00:33 This is known as a tailor hammer and it's light weight, it's small, it's easy to carry around, and to be frank, I hate it - it's my least favorite kind of hammer.

    00:41 It's just not, 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.

    00:51 In contrast, this is Tromner hammer, it's got a lot more weight to it, a lot more give when you're, when you're really applying to the tendons and most importantly it's not as hard on the tip, so you can really bang on your fingers, without ultimately causing yourself discomfort so I find the Tromner hammer to be very useful to have around.

    01:10 Sometimes they also come with the Bolam Test pinprick or the ability to test light touch as well on the back of the hammer.

    01:22 Okay. So with that, lets 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.

    01:38 Just like C5 controls 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 bicep tendon and then I'm going to apply a swing as follows.

    01:57 When we think about the strength of the reflex, there's a range that we have from zero to four.

    02:03 The normal range is typically two and three, so two being the lower end of normal and three being the upper end of normal.

    02:10 That being said, a one out of four reflex is also quite normal particularly since, particularly if it's the same on the other side.

    02:18 In contrast, if four out of four reflex is hyporeflexia, whether or not it's associated with clonus, and then a zero out of four reflex, is essentially a mute reflex.

    02:31 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 zero out of four reflex or certainly an attenuated one.

    02:41 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 three or four out of four on the spectrum.

    02:56 So, again, this is the biceps tendon reflex, I'm applying a good swing to my hammer to really make sure I'm getting the full weight of my reflex hammer, that's C5.

    03:07 Now we move down to the brachioradialis muscle and then I'll palpate on the belly of the brachioradialis muscle here which we're 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.

    03:25 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.

    03:33 Next, we'll do the - 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 patient, what position the patient might be in.

    03:45 I find it's really easy to just actually hold the forearm and hit the triceps muscles in this way.

    03:54 By doing that I'm getting contraction of the base of his triceps which I can actually even feel in my forearm here.

    04:01 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.

    04:18 So that was C5, C6, C7, very straight forward.

    04:22 Now, we're going to move on to the lower extremity reflexes.

    04:25 And now moving on to the lower extremities, there's two reflexes we're going to look for down there.

    04:30 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.

    04:40 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 three out of four reflex on the right and comparing with the left which is about the same depending upon the strength of my hammer, so as you can see, he may have had a one to two out of six 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.

    05:12 It's really when you're looking for a symmetry that would be more concerning.

    05:16 So the next deep tendon reflex in the lower extremity is the ankle reflex and this is going to be L5-S1, which involved in the plantar flexion of the foot.

    05:26 I'm going to basically put his ankle at approximately 90 degrees of dorsiflexion and I'm going to hit a few centimeters above the calcaneus.

    05:37 And you could see a nice downward plantar flexion there in his right foot.

    05:43 In some instances it can be difficult to wrap around to tap on the Achilles tendon particularly in a bed-bound 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.

    05:58 I'm getting just as much of a response with this approach as I would by trying to find and hit the tendon.

    06:05 So sometimes, you may come across a patient who appears to have no evidence of reflexes particularly in the lower extremities and so we say those were mute reflexes.

    06:15 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 extremities reflexes.

    06:26 This is an effort to try and distract the descending input from the cortex from inhibiting the action of the spinal reflex.

    06:36 So what we're going to have you do Shaun, is I just want you to put your fingers together like this and then I'm going to again check your knee reflex while his pulling his hands apart and I don't want you to pull your hands apart until we're ready to go.

    06:50 So now, go ahead and pull your hands apart and he already had a robust reflex, but simply doing that Jendrassik maneuver - 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.

    07:10 I've seen even some neurologist will not only have the patient do this Jendrassik maneuver, but also have their head turn their head 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.

    07:21 Next thing that is worth us doing is also looking at how to assess reflexes in a patient who is bed-bound because that's certainly something that you'll come across.

    07:30 You're not just going to be assessing reflexes in the outpatient setting and some patients, they just can't sit up on the side of the bed but you still need to get the reflexes.

    07:38 This would be particular in the case in an ICU level patient.

    07:42 So Shaun, if I could have you lie down for me please.

    07:52 For the most part checking the upper extremity reflexes is going to be same.

    07:56 The only caveat is I'm simply going to draw his arm across his chest and hit his triceps just like this, he had the response I'm looking for which is not unlike how we were doing it before.

    08:07 Shown on this side, I'm just doing that. It's the lower extremities where it can be really challenging to figure out how to position the patient appropriately.

    08:16 So what I typically do is I'll - let me lift up your thigh here, just relax your leg.

    08:22 I've just got his leg enough off the table that I can easily get that reflex without any problems and patients for whom it's subtle, you may just want to be looking at the quadriceps muscle and see if it contracts, and then in terms of the ankle jerks, I already showed you before, then you could just lift the feet up like this and hit your hand that's one way.

    08:42 Another way to do will be to figure four the patient's legs like this, so that the ankle is now exposed and I'm bringing his, dorsiflexing his foot and hitting his ankle like such, and that allows me to get a good reflex in a bed-bound patient as well.

    About the Lecture

    The lecture Reflex Testing by Stephen Holt, MD, MS is from the course Examinations of the Neck and Back Region.

    Included Quiz Questions

    1. C5
    2. C8
    3. C4
    4. C6
    5. C7
    1. C6
    2. C4
    3. C5
    4. C7
    5. C8
    1. C7
    2. C4
    3. C5
    4. C6
    5. C8
    1. L3/L4
    2. L2
    3. T12
    4. L5/S1
    5. L1
    1. L5/S1
    2. L3/L4
    3. L2
    4. L1
    5. T12

    Author of lecture Reflex Testing

     Stephen Holt, MD, MS

    Stephen Holt, MD, MS

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