“Peripheral neuropathic pain is the term used to describe situations where nerve roots or peripheral nerve trunks have been injured by mechanical and/or chemical stimuli that exceeded the physical capabilities of the nervous system”
Let’s start by saying that this paper is written by one of the gurus of the Physical Therapy profession and pain science theory. David Butler has done much to advance the profession in terms of understanding pain and how patients perceive pain.
When a tissue takes more stress than it can handle it gets injured. This also holds true for the nerves of the body. If they are compressed, stretched, inflamed, the person will experience a neuropathic (origninating from the nerve) pain that is caused by a peripheral (not coming from the brain or spinal cord) nerve.
“Hyperalgesia describes an exaggerated pain response produced by a normally painful stimulus, and allodynia characterizes a pain response created by a stimulus that would not usually be painful”
When a nerve gets injured, it can create an abnormal pain response. The pain response can be very elevated. For instance, I have treated patients that experience allodynia (non-painful stimuli creates a major pain response) and these patients experience intense pain with the stroking of a cotton swab. This abnormal response, although not common, is a sign of miscommunication between the nerve and brain regarding the stimulus.
“Movements or positions that expose sensitized neural tissues to compressive, friction, tensile or vibration stiulu can be symptomatic for patients experiencing a musculoskeletal presentation of peripheral neuropathic pain, and these phenomena would be described as mechanical hyperalgesia/allodynia”
Hyperalgesia: picture ice on your skin. Normally it is very cold and uncomfortable. For someone experiencing hyperalgesia, it may as well be a gunshot wound. Their brain can’t differentiate between something that should cause a little pain and something that should cause a lot of pain.
Allodynia: picture a butterfly landing on your knee. Now imagine that the butterfly has knives for feet and every time the wings beat it sounds like nails on a chalkboard…that’s allodynia. Something that should not be painful…sunshine and rainbows…now causes pain.
Anything that moves a nerve, compresses a nerve, vibrates or stimulates a nerve can cause this symptom. Good luck with life. Is there hope for this patient? Yes, but the road won’t be easy. These patients exist and I have had the badge of honor of treating some of these patients that do not present with a typical “mechanical” presentation.
“peripheral neuropathic pain associated with musculoskeletal disorders will generally exhibita a relatively consistent stimulus-response relationship”
What this means is that I would be able to create pain consistently with the same stimulus over and over again. This would be a good CIA interrogation technique (in the middle of watching Homeland as I type this). Unfortunately, the patients that are experiencing this sensitized nervous system have done nothing wrong, but the suffering will continue until the patient meets a therapist that has actually read the research on this condition. Pain neuroscience education is being taught in schools currently, but when I was in school there was no mention of this. I don’t think that I am that old, but apparetnaly I am.
“…neuronal injury near the Intervertebral foramen can affect nerve fibers associated with more than one spinal cord level. Central nervous system neurons become sensitized after peripheral nerve injury and expand their receptive fields”
This sucks. Picture a house of cards. What happens when you pull on of the bottom cards? It doesn’t go quietly…that’s for sure. When one nerve gets irritated or sensitized, it has the ability to sensitize surrounding nerves. Think domino effect. When other nerves get irritated, it expands the location that symptoms are felt. The spine is the roadmap for the body and each segment of the spine can create a negative sensation at other locations of the body. If there are more areas that are affected, then there is a greater effect on the segments further away from the spine’s typical referral pattern.
“Neurodynamic tests…challenge the physical capabilities of the nervous system by using multijoint movements of the limbs and/or trunk to alter the length and dimensions of the nerve bed surrounding corresponding neural structures…. ‘positive’ response to a neurodynamic test that would be considered suggestive of increased mechanosensitivity in neural tissues. First, the test reproduces the patient’s symptoms or associated symptoms, and movement of a body segment remote from the location of symptoms provoked in the neurodynamic test position alters the response. Second, there are difference in the test response between the involved and uninvolved sides or variations from what is known to be a normal response in asymptomatic subjects.”
This is a mouthful, but here we go. A test that assesses the sensitivity of the nervous system involves multiple components. For example, to test the knee one would look at the knee because it is local to the area that is being assessed. The nervous system is a system that starts at the brain and then descends throughout every segment of the body. To test this system, the entire system should be tested. If testing an area of the nervous system away from the area of complaint can alter the complaint, then the nervous system impairment is ruled in.
If you have a pain in the big toe and it gets worse when you bring your chin to your chest, the problem is not the toe. It is something between the toe and the chin that moves when you move your chin to chest. The nervous system is one of the possibilities. Not the only possibility, but probably the highest probability on the list of causes. This may indicate a sensitive nervous system.
“Alteration in resistance perceived by the examiner during neurodynamic testing is considered one of the most important signs of increased neural tissue mechanosensitivity…Similar activity from the hamstrings is associated with the resistance encountered ruing straight leg raise in asymptomatic and symptomatic subjects…changes in knee extension mobility secondary to releasing the neck flexion component of the slump test are not associated with changes in hamstring activity in asymptomatic subjects.”
Did I not state that the author is one of the top dogs of the PT profession. There is a saying that all professions should own their terminology. The best profession at this is probably lawyers, as they coined the term legalese. Dr(s) Nee and Butler have done a great job of owning the professional language in this article. I am a part of the profession and I have to read and re-read some of these statements.
Picture a rope that extends from your head and descends down the spine and into one butt cheek and down the leg to the bottom of the foot. If you bend your head forward, you pull on the rope. If you straighten your leg while seated, you pull on the rope. If you slouch, bring your chin to your chest, bring your knees to your chest and then try to straighten your knee you put a ton of pull on the rope. Now imagine that ever time that the rope is pulled that you experience pain at some location in your body. The final position would suck and your body will do every thing in its power to keep from straightening the leg because the rope just can’t pull any further. Now…if you were to look up you would provide some slack to the rope and open up some room to straighten the knee a little further. This is not indicative of hamstring “tightness”, but more of nerve “tightness” or sensitivity to being pulled on.
“ ‘positive’ neurodynamic test does not enable the clinican to identify the specific site of neural tissue injury…merely indicates…increased amount of mechanosensitivity.”
Any point of the rope could cause symptoms. We can’t say exactly which point of the rope is problematic…so we start to treat the entire rope. We can change the testing sequence (such as move the knee prior to moving the spine) in the hopes of biasing one portion of the rope over other portions, but it is not for certain. It doesn’t hurt to try to alter the sequence of movements in order to try to narrow down the location of sensitivity…oh wait…it does hurt to try it. Physiology funny.
“…neural structures will be subjected to different mechanical loads depending upon the order of joint movement durin gneurodynamic testing…the testing sequence has been shown to alter the mobility and/or symptom response during straight leg raise…and a median nerve biased ULNT”
This means that when your nerves are sensitive, we may be able to figure out where in the rope there is a problem by changing the position of your joints prior to testing the tension in the rope. For instance, if we move your toes towards your face prior to having your slouch and straighten your knee we are theoretically assessing the rope as it crosses the ankle joint, as this increases the load on the portion of the rope as it crosses that joint first prior to pulling on the rope with any other portion of the test.
“Provocation of symptomatic complaints during nerve palpation does not necessarily identify the site of neural tissue injury, because the entire neural tissue tract can become mechanically sensitive after injury to a particular nerve segment…Additionally, hyperalgesic/allodynic responses in uninjured neural tissues may be the result of alterations in central nervous system processing of afferent information.”
There are some tests that we use in PT in which we tap your nerve and if it provokes your pain then we believe that we have found the motherload. UREKA! X marks the spot and it must be the nerve that is directly under the location that I hit that caused the patient’s pain. This is one of the ways in which carpal tunnel is diagnosed. No good. An irritated nerve at any point in the chain can cause an irritation at any other point in the chain. You want to be seen by a therapist that understands this basic notion. If you are treated by a therapist for carpal tunnel, the therapists better be damn sure that the pain is coming from the carpal tunnel, though the symptoms may be coming from an irritation at the elbow, shoulder or neck…you will probably fail conservative care. You know what happens when you fail conservative care? The care becomes not so conservative anymore.
“Mechanical and chemical irritation can lead to musculoskeletal neural tissue injury. Repetitive compressive, tensile, friction, and vibration forces acting near anatomically narrow tissue spaces through which neural structures pass can cause mechanical irritation. Injured somatic tissues adjacent to nerve structures release inflammatory substances that can chemically irritate neural tissue.”
Essentially what this section is saying is that there are many things that can injure a nerve. Most people think of a traction injury such as a stinger in football or a significant spinal cord injury to injury nerve, but any load on the nerve that is greater than that nurse talents or a chemical around the nerve that the nerve cannot tolerate will also sensitizing nerve.
“Mechanical or chemical stimuli that exceed the physical capabilities of neural tissues induced venous congestion and therefore, impede intraneural circulation and axoplasmic flow. Subsequent hypoxia and alterations in microvascular permeability causing an inflammatory response in nerve trunks and dorsal root ganglia that leads to subperinurial edema and increased endoneurium fluid pressure.”
This is fancy talk for when the nerve gets injured, there is less circulation and leads to increased fluid pressure. Less circulation leads to decreased oxygen flow to that area, as oxygen is carried on the blood. When a nerve gets pressure placed on it from either a mechanical or chemical source, it could become sensitized.
“Emotional stress can exacerbate symptoms of nerve injury partly because the chemicals associated with stress are capable of stimulating a IGS. ”
When we stress there is a chemical change that happens in our body. We Edrene we release adrenaline that whole flight or fight sense. And because of this it can cause her nerves to fire inappropriately. This can also increase pain. For some patients who have this type of chronic pain that is to desensitize nervous tissue, meditation and calming of the nervous system can actually be a good intervention.
“… Pain is produced by the brain when it perceives that body tissues are in danger and the response is required. ”
This is extremely important. Without a brain there is no pain. This is a very common statement that is going on in the pain neuroscience education field. It is because of our brains output that we are experiencing pain. This output can occur in the absence of a painful stimulus. If our brain senses danger then it will elicit a pain response to prevent us from doing that action. For instance if your tissues are sensitized and you are thinking of going out parachuting, your brain may actually start to produce pain from both the adrenaline rush and from the perception of danger.
“The broad goals for managing musculoskeletal presentations of peripheral neuropathic pain are to reduce the mechanical sensitivity of the nervous system and restore its normal capabilities for movement.”
About 90% of patients attending therapy are doing so because they have pain that is affecting a portion of their daily activities. If this is the case, then we (as therapists) should be working to decrease your pain to return you (the patient) back to your activities without limitations. We have to not only reduce your nerves sensitivity, but then have to teach the nerves to tolerate varying movements that may provide tension or compressive forces without them screaming for mercy.
“… Therapist employs a system of reassessment to judge the impact that intervention strategies have on the non-neural and neural components of the problem.”
This is something that is overlooked by many patients. Many patients are unsure of what to expect from PT. I describe it to some as one big science experiment. There will be one patient and I will perform one intervention and determine how that one intervention affected the patient’s pain/function. If it worsened pain/function, then that is probably not the way that I should move the patient as an intervention. If the exact opposite movement also worsens the patient, then the patient may not have a directional preference. From here, the game begins. We have to assess the patient after each movement. When I say that patients overlook this, it’s because the patient’s may not understand this. Unfortunately, if the patient doesn’t understand that we need to perform interventions and recheck how that treatment affected the patient…the patient won’t ask any questions about treatments until their sessions are almost over. We as therapists have to make sure that the patient understands how the relationship between PT and patient can be optimized. Communication is the first way to optimize treatment.
“Appreciating the mechanical continuity of the nervous system may also assist patients in understanding why movement of body parts removed from the site of symptoms may be used as a treatment strategy to mobilize neural tissues. The impact movement has on the nervous system is not only mechanical; discussion should include explanations of how intraneural circulation, axonal plasmic flow, and nociceptors in neural connective tissues can be affected by mechanical loading.”
This statement is mind blowing because the authors are so thoroughly saying that one of the jobs of PT’s is to educate the patient on how the nervous system responds to exercises, manual therapy and movement in general. The problem with this is that I don’t think that I could do a thorough job of educating the patient on this topic. I can give a general explanation, but this topic is very complex in terms of how the body sends and receives signals.
“educating patients about the neurobiological mechanisms involved in the clinical behavior of the presentation of peripheral neuropathic pain can reduce the threat value associated with their pain experience and alter any unhelpful beliefs they may have about their problem. ”
This gets back to educating the patient how stress affects their system, by increasing neural output for the possibility of flight or fight. If a nerve is dysfunctional, then sending more messages through that nerve may lead to increased dysfunction. The patients have to understand this because if they can understand the difference between hurt vs harm the patient may have less pain with activities that they expect to hurt, but understand aren’t harmful.
“Gliding techniques, or ‘sliders’, are neurodynamic maneuvers that attempt to produce a sliding movement between neural structures and adjacent nonneural tissues”
I first saw these movements used way back in 2003. I am sure that they were used well before then, but I was given an education on them prior to entering PT school. I was volunteering with a great therapist, Bill White, and he was explaining the mechanics of how the nerve glides up and down the track. The mechanics of it made sense way back when, but the neurophysiological response wasn’t explaned to me at the time and I’m glad because I wouldn’t have understood it at the time.
“…purpose of neurodynamic tensile loading techniques is to restore the physical capabilities of neural tissues to tolerate movements that lengthen the corresponding nerve bed…tensile loading techniques are not stretches; these neurodynamic maneuvers are performed in an oscillatory fashion so as to gently engage resistance to movement that is usually associated with protective muscle activity.”
This goes back to what was described previously. When performing exercises to improve the nerve’s tolerance to movement, we have to move in such a way that systematically loads the nerve biasing one movement or another. In doing this, it is done in an oscillatory manner, meaning pressure on (from one end and off the other) and pressure off (from one end and on the other). This will build tolerance to movement in the nervous system, which theoretically will reduce sensitivity to movement over time and reduce pain.
In the end, it’s worth a shot if you have pain that has not responded well to a repeated movement or joint level approach, chemical or inflammatory approach or biopsychosocial approach.
EXCERPTS TAKEN FROM:
Nee RJ, Butler D. Management of peripheral neuropathic pain: integrating neurobiology, neurodynamics, and clinical evidence. Phys Ther in Sport. 2006;7:36-49.
The abstract can be found here