The Neuroscience of Chronic Pain

By: admin Published: March 10, 2013

by Jay McCallum, PT, DPT, OCS

This post has been a very long time in the incubator, partly because we’re all so busy and partly because we wanted to be able to give you both some science and some clinical reality.  It started last October when Amy and Jay went to a conference in Portland on the topic of chronic pain.  It was taught by a pair of amazing researchers, Paul Hodges and Lorimer Moseley.  Paul and Lorimer are both physical therapists – ‘physiotherapists’, actually, given that they’re Australians – but they have devoted their professional lives to the study of how pain works and between them have published nearly 300 scholarly articles on the topic.

Because they covered so much ground this is going to be the first of a three part blog.  I’ll talk about Paul’s work today, and then try to cram Lorimer’s material into a second blog, and finally talk about our experiences in the clinic working to implement their findings into actually treating patients.

How Does Chronic Pain Affect How We Move?

This is really what Paul Hodges’ work is about.  He is best known in the world of physical therapy as the researcher who told us all that the transversus abdominus is important in stabilizing the spine, but that’s really not at all fair to the body of his work.  What he has focused on is how the body solves the problem of keeping a stack of bones like the spine stiff enough that it doesn’t collapse, yet mobile enough to move.  And, what he’s found is that people do it in lots of different ways (of course).  There are, however, some patterns once you step back from the detailed specifics, and, more importantly, people who have a history of back pain tend to use a different set of strategies than people who don’t have back pain.  Most of the research here is focused on back pain, but it’s quite likely that similar patterns are at work with other locations of chronic pain, like the neck.

Generally speaking, the muscles of the trunk can be divided into muscles that are closer to the spine and those that are further away, with of course some muscles situated in a bit of a gray zone in between.  And Paul’s work suggests that the ‘normal’ way that we move is that the muscles that are closer to the spine activate to create just the right amount of stiffness to support the loads we put on our spines, while those further from the spine are primarily concerned with generating movement of the spine.

The best known of those deep, stabilizing muscles are the multifidus and the transversus abdominus, and the ones we tend to forget about are those that make up the pelvic floor.    These muscles are relatively small, located right in there close to the spine, and are designed to stay ‘on’ for long periods of time at a relatively low intensity.  They are also supposed to ‘pre-activate’, meaning that before you go to pick up that pencil on the floor the brain tightens them to stabilize the back.

View from the side of the multifidus, pelvic floor and transversus abdominus

What goes wrong?

We get stuck in a pattern.  When a person first injures his or her back, the body’s reaction is to brace it – to tighten the bigger muscles that are further out from the spine and have longer lever arms to pull on it.  Those muscles normally exist to generate movement, but get pressed into service to hold the injured spine in place.  That pattern is supposed to quiet after a while, but if it doesn’t it can become the “new normal,” the primary strategy for keeping the spine stable.  And that’s really a problem, because those muscles are NOT designed to be on for long periods of time, and so they complain about it, and get trigger points, and make the spine feel stiff all the time.  And they use too much force, so the underlying joints have too much pressure on them.  And they just aren’t very good at this new job, so people hurt their back picking up that innocent pencil because the nervous system didn’t stabilize the spine quite right (but they DON’T hurt their back lifting heavy things, because they consciously brace.  Sound familiar?).  And so, the classic pattern goes, people have further episodes of back pain and each one intensifies this pattern.

Hey!  That’s me!  What can I do??

And…there we have the problem.  Obviously, what we’d LIKE to do is turn off those overactive superficial muscles and re-activate the deep ones.  But, it isn’t quite so simple.  These changes in muscle activation are accompanied by changes in brain structure.  Put more simply, most people have had a LOT of practice at this pattern.  We’ll talk about this more in my third post, but a couple of key points is that pain of this type is not just a ‘strengthening’ issue – it’s much more about coordination.  And you have to work at it from a lot of angles, trying to both activate the deep ones (intentional exercise, practice, feedback) and quiet the overactive ones (stretching, motion, relaxation, massage and manual therapy).  Most importantly, treatment needs to be individualized and very attentive to details, which is how we do things at CoreBalance Therapy.

If you want to learn more, give us a call at 928-556-9935 or email us at [email protected].

The serratus anterior – the ‘forgotten muscle’ in shoulder and neck pain

By: admin Published: August 30, 2012

by Jay McCallum, PT, DPT, OCS

Board Certified Specialist in Orthopaedic Physical Therapy

What the heck is the serratus anterior?

Because the serratus anterior is largely hidden from view underneath the shoulder blade, it is remarkably easy for both patients and clinicians to forget about this vital muscle.  It originates from the underside of the shoulder blade near the inner edge and has a broad attachment to the ribs.  It gets its name from the way that it is serrated, like a knife blade, as it attaches into the ribs, and is anterior (forward to) the shoulder blade.  Even though the serratus anterior is not visible on most people’s bodies, it is normally a very strong and fairly large muscle.

Serratus Anterior side view

Okay…so what does it do?

And here is where the confusion REALLY sets in.  The serratus anterior has historically been though of as performing two primary functions.  The first is to hold inner edge of the shoulder blade against the ribs, preventing ‘winging’ of the shoulder blade, as shown here.

Winging of the shoulder blade due to serratus weakness or paralysis

However, winging of this type is fairly rare, occurring mostly with injuries to the nerve that supplies the serratus anterior, the long thoracic nerve.  The second commonly thought of function for the serratus anterior is ‘protraction’ of the shoulder blade, pushing it forward relative to the body  in a punching motion.

So, the reader is thinking at this point, if my serratus anterior is weak then my right hook isn’t what it used to be, and I have a funny looking shoulder blade.  Tell me again why this is important?  Turns out that the serratus anterior does two other things that are a bit more functionally useful to us.  The first is that it is the strongest, best positioned muscle to create upward rotation of the shoulder blade, basically aiming the socket up.  In order to reach higher than about shoulder level the shoulder blade must upwardly rotate.  If the serratus is weak, then the shoulder blade literally can’t get out of the way of the arm, and that leads to pinching at the top of the shoulder, frequently known as subacromial impingement syndrome or subacromial bursitis.  Over time, it can even lead to development of a rotator cuff tear.  The other really important function of the serratus is to solidly anchor the shoulder blade to the thorax with use of the arm.  If the shoulder blade doesn’t have that stability, then the rotator cuff must work much harder, rather like walking in sand rather than on a hard surface makes your legs work harder.  That can, in turn, lead to rotator cuff tendinitis.

What does this have to do with my neck pain?

The serratus anterior isn’t the only upward rotator of the shoulder blade, it’s just the best one.  If it’s weak, the body goes looking for another way to accomplish the movement, and the next muscle in line is the upper trapezius.

The upper trapezius - look familiar?

Unfortunately, the upper trapezius is not particularly good at creating upward rotation of the shoulder blade, so in this role it has to work extremely hard, and so can become quite painful.  It also attaches into the skull and upper neck, and so significantly compresses those structures when it is activated.

How would I know if my serratus is a problem?

Anybody with shoulder pain should certainly have their serratus anterior strength assessed by a physical therapist, as serratus anterior weakness and/or inhibition is extremely common to a range of painful shoulder conditions.  The serratus anterior should also be examined for most patients with neck pain, particularly those who find that their pain is brought on by use of their arms – i.e. experiencing neck pain with lifting, carrying, cleaning, etc.

What can I do about it?

Like most muscles, serratus anterior strength is very activity-specific.  A common pattern is that a patient may be able to generate significant force into protraction – the ‘punching’ motion, but have much less strength with upward rotation of the shoulder blade.  And if there is a strong compensatory pattern already in place it can be quite difficult to re-establish a more efficient movement pattern.  So, while the internet has many serratus anterior exercises a short Google search away, people with symptoms are best advised to seek the guidance of a physical therapist, who can identify the specific pattern of weakness that may be present and design an individualized exercise program to address it.

If you’re in Flagstaff or northern Arizona and want this type of evaluation, then please call us at 928-556-9935 or email us for an appointment!


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