In order to discuss the examination technique for myofascial trigger points, I thought we should review the clinical features of myofascial trigger point pain. Myofascial trigger point pain involves a localized tender spot or nodule in a taut band of skeletal muscle. So we call this like the trigger point is here, the taut band and the tender point in the taut band. And it has a local twitch response characteristic, the taut band. And there's an associated referred pain. And clinically, obviously, we want the referred pain to actually represent the patient's familiar pain, their usual pain, the pain complaints that they've come in to see you for. So, let's first look at some of the evidence that shows that this is actually a localized spot or nodule. That it's not just generalized myalgia, but it is actually a knot in the muscle that is causing the pain. What are some of the studies that support that? We have, in 1993 Hubbard and Berkoff published a study that showed that myofascial trigger points have spontaneous needle EMG activity. They placed a monopolar needle electrode into a trigger point site and also into the same muscle at a non-trigger point site, about two centimeters away. The trigger point showed spo, significant spontaneous electrical activity and the normal muscle was electrically silent. This was a huge breakthrough for myofascial pain because now there was an electrical marker, and myofascial pain could be classified as a neuromuscular disorder. Here is a video that shows the insertion of the monopolar needle electrode looking for the spontaneous electrical activity. And here you can see on the monitor the amplitude of the electrical activity in the trigger point versus the amplitude of the electrical activity in the normal muscle. And as you can see, the amplitude in the trigger point is much much higher than that in the normal muscle. So we know that trigger points are very discrete small spots in skeletal muscle. When the needle electrode was moved less than two millimeters away from the nidus of the trigger point, the electrical activity would stop. How do we know that the trigger point is just a is a tender spot? Well there at least two different studies that have looked at the tenderness of trigger points versus normal muscle. There was a pressure algometry study one by Reeves and his cohorts and another by Hong and his cohorts that documented that trigger points were more tender than the surrounding muscle. In this early study by Reeves and his colleagues, the pressure algometer was used to measure the sensitivity over the trigger point itself and then a centimeter away over normal muscle. The pressure algometer applied pressure of in kilograms per centimeter square, the rubber tip being a centimeter square. And the rate of application was one kilogram per centimeter squared per second, and when the pressure sensation turned painful, patients would raise their hand or say stop. And that was the measurement that was taken. And the data shows that the trigger point sites tolerated significantly less pressure than the normal muscle. As you can see here, the trigger points were tender between two and three quarters and three and point six kilograms per centimeter squared. And these were head neck muscles. The superficial masseter, the anterior temporalis, the splenius capitis, the trapezius and the semispinalis capitis. And the non-trigger point sites in the same muscles tolerated significantly more pressure. Hong and his colleagues did a similar study. They looked at pressure sensitivity over the trigger point itself. They looked at how sensitive was the taut band but not the trigger point and how sensitive was normal muscle. They found that trigger points were significantly more tender than active trigger points were significantly more tender than latent trigger points. Latent trigger points were significantly more tender than normal muscle. Active trigger points were significantly more tender than non-trigger point sites within the taut band and also significantly more tender than normal muscle. Here are some of the numbers. Looking at compression at the trigger point, compression at the non-trigger point site in the taut band, and compression of normal muscle. Now this idea of a taut band has also been experimentally, verified. Taut bands are actually very easily palpated. And they are very common in normal control subjects. The taut band is where the trigger point is found. There is a rabbit model, and the rabbit model has allowed various experimental studies to be conducted that have documented various characteristics of the taut band. The taut band is dependent on an intact nerve supply. Now the taut band also has this characteristic called the local twitch response. The local twitch response is actually clinically very hard to elicit consistently, but it is a characteristic of the trigger point. This means that when the trigger point is found in the taut band, and if you press on the taut band it's sort of a strumming fashion, almost like a little guitar string. That the taut band containing the trigger point will actually contract. Again there is a rabbit model that has allowed studies to be conducted on the twitch responses itself. Hong and his colleagues performed a very extensive study on the twitch response. They used a setup where they put a solenoid to stimulate the taut band and they measured the EMG activity with a Caldwell Quantum 84 EMG machine. And this is what they found. They, they stimulated at various points in the taut band. So if the taut band was stimulated directly over the trigger point, the twitch response was quite pronounced. So you can see here the twitch response in the muscle. If on the other hand they were half a centimeter away from the taut band outside of the trigger point there was almost no response. So they were just half a centimeter away on either side of the taut band and there was no twitch response. If they measured or stimulated the muscle half a, a centimeter away from the trigger point, but in the taut band, they got some response, but it was much smaller than if they stimulated at the trigger point site itself. And if they stimulated three centimeters away from the trigger point in the taut band, they got no response. So the trigger point really is the nidus where, if you stimulate there, that's when you get the twitch response, most reliably. The twitch response, it turns out, is dependent on an intact nerve supply, this spinal cord reflex. If the spinal cord was sectioned, then, what happened was, the twitch response went away, but then, after about 30 minutes, it started to recover, and after about two hours, it was almost all the way back to normal. If, however, the motor nerve was transected, there was no recovery. And there was no more twitch response. So the local twitch response has been demonstrated by EMG. The rabbit model exists. It's localized to the taut band. It's best elic, elicited at the trigger point. And it is a spinal cord reflex. The other feature of myofascial pain is obviously the referred pain. That is sort of what we're looking for because clinically that's what's causing the patient's pain and disability. So, we not only want to elicit referred pain if we suspect a trigger point, but we also want to make sure that it's the usual pain, or the familiar pain that the patient has come in complaining of. Now what are some of the palpation techniques? We want to palpate the trigger point. We have to use the tip of the index finger. The tip of the index finger is about one centimeter squared. Now larger muscles may require the use of a stronger digit such as the thumb in order to be able to apply enough pressure in order to elicit a painful response. If we want to palpate the trigger point, we can use either flat palpation which is demonstrated on the left, where you use the flat finger and you can roll over the trigger point, roll al, or move along the taut band to find the most tender spot, and then apply pressure. One of the most important things about the palpating finger is that it have a short fingernail. Long fingernails will complicate the clinical picture because the patient will experience pain, but isn't necessarily the pain of the trigger points, it's probably the pain of an untrimmed fingernail. So myofascial examiners may, do need to have nicely trimmed and short fingernails. Some muscles lend themselves to pincer palpation. That's illustrated on the right side of this slide. Where you can pick up the muscle and hold it between your fingers and apply pressure along the length of the muscle that way. Here's an example of a flat palpation in the cervical region looking for trigger points, and you can see that the operator is moving up and down along the taut band looking for the most tender spots in the muscles in the neck in that region. Here's an example of pincer type palpation. This is the sternocleidomastoid muscle. And again the operator is moving up and down the sternocleidomastoid muscle feeling for taut bands, and looking for the most tender spot within the taut bands. Sometimes if the muscle is put on a very slight stretch, the taut bands become more apparent. And so you can then feel the taut bands because they tighten up more with a slight stretch than the normal muscle. Some of the bigger muscles in the back may require a thumb instead of the index finger. And you can see here, also, the application of pincer-type palpation to the upper trapezius muscle, the lower right picture. Active trigger points require significantly less pressure than latent trigger points to elicit a referred pain pattern. Now, based on the algometry data from Reeves and his colleagues and Hong and his colleagues, palpation really requires up to two to four kilograms per square centimeter of pressure to elicit a pain response. That's important to remember, because if you don't apply enough pressure then you won't actually get the painful response and you'll miss the diagnosis. Now the other factor that plays into the examination of trigger points is how long you hold the pressure that elicits pain. Based on the documented delay in the emergence of the referred pain patterns, and Mense's theory of the unmasking of latent connections in the spinal cord, palpation pressure should be held for at least 10 to 15 seconds to allow the referral pain, pattern to develop. So this is also very, very important. If you find a trigger point and you ask the patient, well, do you feel pain anywhere else or only where I'm pressing, and you're gone again in, in a, in less than two or three seconds, they're going to say no. But if you stay on the trigger point and you wait, and you count to yourself very patiently, two, three, four, five, six, seven, eight, nine, ten. Oftentimes at that point the patient will go, oh, yeah, now I feel the pain. That's my pain, that's my headache. Or, you know, that's, that's my shoulder pain. It's, it's, it's there. That's it. So you need to be patient when looking for trigger points. Find the taut band, find the most tender spot, apply enough pressure, two to four kilograms per centimeter squared. A good marker is that the fingernail should blanch. And if you use the tip of the index finger on smaller muscles, and you're really focusing the pressure onto the trigger point. And similar if you're using pincer palpation. If you use just two fingers, then, you can get more focused pressure on the trigger point itself. And, once you find the trigger point, be patient and hold. Sometimes, a referral pattern is there immediately, and the patient will say oh, wow, I can feel the pain. But sometimes it's just really sore, and they don't really feel the referral right away. The other thing is that it's not necessary to put on four kilograms of pressure when two kilograms is enough. If you watch your patients' reaction, they typically, with a painful trigger point, will wince or withdraw. That's very, very typical. It used to be called a jump sign, which is to be differentiated from the twitch response. But the jump sign is usually the patient going, wow, that's really painful. Because they really don't know that these muscles are sore, the ones that are so far away from where their actual pain is. And so it's a surprise, but again just be patient, hold the pressure, allow the referral pattern to develop, and then find out, is that your pain? Is that what you've been feeling or is that completely different, is that not similar to your pain? And that will help you in the diagnosis. It's also important to remember that multiple trigger points may re, refer overlapping pain patterns that make up a patient's pain. So here's an example of upper trapezius, sternocleidomastoid, and temporalis trigger points producing a headache pain complaint. But the same thing happens in other body parts as well. Myofascial pain really is ubiquitous. For example, pelvic floor musculoskeletal disorders are common in women, and too often go unrecognized during the evaluation of pelvic pain syndromes. And although they're well described in the literature, these disorders cause diverse symptoms that may be missed by a tradition examination of the cervix, the uterus and the adnexa. Screening the infero, inferolateral pelvic floor musculature during a routine pelvic examination is very useful for identifying spasm and trigger points contributing to, or resulting from, a patient's pelvic pain. Again, the idea that a patient's pelvic pain, may have caused the trigger points, but the trigger points will now be contributing to the pain. So, we need to treat both, whatever the acute, pelvic problem is, but we also need to treat the trigger points, otherwise they end up with chronic pelvic pain. Another example is butt and hip pain. There are at least three potential trigger points in the gluteus maximus muscle. The medial trigger point is found adjacent to the lower sacrum, near the muscle's medial attachment. And there are two lower trigger points in the muscle. One that lies near the ischial tuberosity, and one that lies on the inside edge of the gluteal fold region, between the tailbone or coccyx. And if you can identify these trigger points you can help people that have hip and buttock pain. There are also those trigger points that cause abdominal and inguinal pain, especially after hernia and hernia repair. The internal and external oblique muscles may be one of the guilty parties for chronic pain in this area. Examination requires deep palpation to reach through the overlying tissues. And as you can see in this picture, most of the pressure is still applied with only one digit, because it's important, again, to apply enough pressure to the trigger point itself. It's not, we're not looking at generalized muscle soreness. We want to find the trigger point that's causing the pain, and it's a small nodule somewhere in the belly of the muscle typically. So myofascial pain is ubiquidwis, ubiquitous. [LAUGH] And recognition and appropriate management are essential for successful treatment outcomes for myofascial trigger point pain. [SOUND]
