Motor adaptations to pain

This Blog was written together by Jukka Kangas and Wouter Geerse.

INDIVIDUAL RESPONSE to patho-anatomical changes and movement dysfunctions

Physiotherapists are aware that structural changes in musculoskeletal system don’t correlate directly with pain or functional capacity. In scientific world it is widely accepted that people respond individually to patho-anatomical changes (O’Sullivan 2005, Kangas 2011) and they adopt very different motor behaviors in order to cope with pain. On the other hand, physiotherapists in general don’t seem to be equally analytical when the relevance of movement findings is considered. Especially in manual therapy circles, it appears that any movement finding can be considered as a sign of “abnormality” and its correlation to the patient’s pain explained as long as the movement finding is in the same region with pain. However, it appears that people respond equally individually to movement dysfunctions as they do to patho-anatomical changes.

NOCICEPTIVE MECHANISM

Individual response to patho-anatomical changes or movement dysfunctions may be related to nociceptive mechanism. Nociceptive mechanism means that nociceptors can be active in the absence of pain perception. The role of nociceptive mechanism is to protect the organism from injury or further injury (Baliki and Apkarian 2015). Nociceptive control of behavior routinely occurs in the absence of consciously perceived pain and motor behaviors are collectively inhibited by nociceptors. From the viewpoint of behavioral selection, it has been concluded that acute pain is not a warning signal but rather is the failure of the machinery (nociceptor activity) designed to avoid pain (Baliki and Apkarian 2015). In other words, when our patient is experiencing pain nociceptive mechanism has failed to avoid it.
From a clinical perspective the variations of the resulting movement patterns for any patho-anatomical change or movement dysfunction appear to be endless. These resulting movement patterns may become behavioral and narrow the available movements strategies relative to the individual needs and environmental requirements. This may lead to monotonous loading of the body region and result in pain. This monotonous loading may be in the area where normal movements are available and therefore it can serve as a compensation area.
Therefore, it is reasonable to suggest that in a clinical assessment we should be seeking factors from the movement and nervous system that are limiting the available strategies for normal movement and potentially maintaining patient’s pain.

A CASE EXAMPLE - Setting the Scene
This was during the course: Contemporary Manual Therapy for the Foot and Ankle. The course took place in Holland in April 2017. Jukka was the instructor of the course and Wouter active participant on the course.
This was a brief demonstration of the influence of the post-traumatic movement dysfunctions of the lower extremity to the radicular symptoms and LBP. A course participant had a chronic low back pain (CLBP) and radicular symptoms into the foot&ankle(F&A). He didn’t have pain separately in the foot and ankle or knee region.

Subjective Examination:
A participant of the course presented himself for the demonstration. He felt local right sided LBP in sitting, which progressed to radicular pain in the right leg with numbness within two hours. At that moment, he had a feeling of stiffness in his low back and a loss of sensation at the ventrolateral part of his right foot.
In the history, he told that once he felt a pain in his foot after he was blocked playing soccer in an external rotation position kicking the ball with the inner side of the foot. This pain disappeared within the normal expected course.
He had a history of L4-5 and L5-S1 stenosis, which was diagnosed 11 months earlier. With the MRI, they also revealed a disc protrusion at L5-S1 with mild nerve compression. The symptoms were progressing rapidly.
A ‘spontaneous’ Baker’s cyst appeared three months earlier and disappeared.

Clinical Reasoning Process:
Patient witnessed typical symptoms related to the lateral stenosis. Furthermore, he had had an accident of the right F&A and spontaneous symptoms in the knee. Therefore, F&A and the knee should be included to the examination plan equally with low back.
Patient had obviously nociceptive LBP and neuropathic leg pain. However, he didn’t seem to have any precautions or contraindications for the physical examination.

Physical Examination:
In neurological screening patient had numbness in the anterolateral part of the ankle and distal lower leg. The reflex of the knee was absent and the Achilles reflex was weaker than on the left side.
In active movements of the lumbar spine pelvis demonstrated a monotonous movement pattern. The right side of the pelvis was rotating only anteriorly. This movement was exaggerated in extension and side-bending to the right. Extension also provoked patient’s LBP. The same movement pattern of the pelvis appeared during squat with both legs. Furthermore, the right knee was constantly mildly flexed in standing.
In passive movement testing (PAIVMS) there were no findings in lumbar segments. Instead extension of the knee and dorsiflexion of the ankle was restricted.

Clinical Reasoning Process:
Considering the patient’s patho-anatomical changes and existing movement pattern of the pelvic region and resulting loading pattern of the low back it was reasonable to hypothesize that the movement dysfunctions of the lower extremity may maintain the monotonous movement pattern of the pelvis. In this case, it appeared that the pelvic region was compensating the dysfunctions below in the lower extremity. The dorsiflexion restriction in the ankle resulted in medial rotation of the talus and lower leg (single leg standing and squat) and the extension restriction of the knee resulted in medial rotation of the thigh (single leg standing and active extension of the knee). Increased medial rotation of the lower extremity may result in anterior rotation of the pelvis from the same side. This would mean increased extension and ipsilateral rotation of the lumbar spine, both further narrowing the intervertebral foramen.

Treatment and re-assessment:
The first treatment included restoration of the ankle dorsiflexion and the extension of the knee with directional specific mobilization.
After the mobilization patient’s ankle and knee was moving normally. Furthermore, the movement pattern of the pelvis was symmetric and normally variable during active movements of the lumbar spine and squat. Interestingly enough the area of numbness was significantly reduced and the reflexes were nearly symmetric compared to the left side.
Observer’s (Wouter) comments:
It was very interesting to see the role of the lower limb movement impairments relating to each other and influencing each other as well as the nervous tissue involvement. Mind- as well as eye-opening, that the knee E/AD techniques could alter the sensibility at the foot and ankle in a more chronic case of a person who believes he has fully recovered from his ankle sprain. This widely spread effect in a variety of tissues cannot be explained only by the local effect at the knee.

The influence of restoring normal movement capacity in the knee and F&A region must also influence the central nervous system. We now know that, at least, it happens the other way around. Acute low back pain directly enhances activity in central pain mechanisms (Vuilleumier et al, 2017).
After an injury, even if the pain is gone, it is not said that also the movement impairments and/or motor control impairments are not present in this case which exceeded the normal time for tissue healing. Pain is a great stimulation do adopt and alter your way of moving, the lack of pain itself is not a stimulation to go back to your ‘old’ and normal way of moving. Thus, altered movement patterns may still be present in the foot and ankle and possibly also in the kinetic chain of the lower extremity.

SPECULATION OF THE CASE

Some questions come up with this case description:
- How to explain the case?
- Why this simple intervention changed patient’s symptoms and movement pattern?
- How to classify the patient’s pain mechanism?
- Why reflexes changed when movement of the ankle and the knee was restored?
- How to classify the disorder?
- What classification or diagnosis would direct the intervention to the mechanism maintaining the disorder?

From a classical perspective in this case lumbar stenosis was giving rise to nociceptive LBP and neuropathic leg pain. However, we need to appreciate the fact that any diagnostic entity may give rise to several different pain types (Kosek et.al. 2017). Furthermore, any diagnostic entity may have accumulative factors amplifying or even maintaining the pain. These accumulative factors may arise from previous injuries and/or pain states and coping strategies. Therefore, there is a high risk that classification of pain mechanism is a simplification of the reality. Kosek et.al. (2017) have warranted a need for a term to identify the neurobiological dimension in patients who have neither obvious activation of nociceptors, nor neuropathy, but in whom clinical and psychophysical findings suggest altered nociceptive function.

Different classification systems exist for musculoskeletal disorders. In a recent study of CLBP population out of 36 possible subgroups, 33 were represented across 294 participants (Rabey, 2016). This is highlighting the variability of CLBP presentations, but also the deficiency of individual classification systems. Therefore, there is a high risk that classifying disorders and implementing classification systems in clinical situations reduces the sensitivity towards individual presentations.
Previous injuries and/or pain areas haven’t necessarily fully recovered even if they are symptom free. People seem to adopt movement patterns that are pain free. This may be facilitated by the nociceptive mechanism, which is subconsciously influencing to the movement patterns. However, getting rid of pain doesn’t equal with restoration of normal function. Limited function must influence to the available movement strategies and may increase the risk of the failure of the machinery (nociceptor activity) designed to avoid pain. This may be part of the abnormal functioning of the nociceptive system.

Hodges (2011) have suggested a theory that argues based on clinical and experimental data that in motor adaptation to pain: activity is redistributed within and between muscles rather than stereotypical inhibition or excitation of muscles; modifies the mechanical behaviour in a variable manner with the objective to "protect" the tissues from further pain or injury, or threatened pain or injury; involves changes at multiple levels of the motor system; and has short-term benefit, but with potential long-term consequences due to factors such as increased load, decreased movement, and decreased variability. Based on our clinical evidence all these adaptations are possible and most importantly individual in their presentations. Therefore, a truly individual approach requires thinking simultaneously within different frameworks and analytical and non-judgemental comparison of concrete findings in each framework.

REFERENCES

Baliki MN, Apkarian AV. Nociception, pain, negative moods and behavior selection. Neuron. 2015 August 5; 87(3): 474–491

Hodges PW. Pain and motor control: From the laboratory to rehabilitation. Journal of Electromyography and Kinesiology. 2011 Apr;21(2):220-8

Kangas J, Dankaerts W, Staes F. New approach to the diagnosis and classification of chronic foot and ankle disorders: Identifying motor control and movement impairments. Manual Therapy 2011; 16: 522-530

Kosek E, Cohen M, Baron R, Mico J-A, Rice ASC. Extended classification of pain states. PAIN 158 (2017) 1395–1399


O’Sullivan P. Diagnosis and classification of chronic low back pain disorders: Maladaptve movement and motor control impairments as underlying mechanisms. Manual Therapy 2005; 10: 242-55

Rabey, M., 2016. Multidimensional Patient Profiles in Chronic Non-specific Axial Low Back Pain: Subgrouping and Prognosis. PhD Thesis. Perth, Western Australia: Curtin University.

Vuilleumier PH, Arguissain FG, Biurrun Manresa JA, Neziri AY, Nirkko AC, Andersen OK, Arendt-Nielsen L, Curatolo M, Psychophysical and electrophysiological evidence for enhanced pain facilitation and unaltered pain inhibition in acute low back pain patients, Journal of Pain (2017), doi: 10.1016/j.jpain.2017.05.008

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