Research Review By Dr. Daniel Avrahami©

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Date Posted:

April 2013

Study Title:

A Neuroscience Approach to Managing Athletes With Low Back Pain

Authors:

Puentedura EJ & Louw A

Author's Affiliations:

University of Nevada Las Vegas, School of Applied Health Sciences, Department of Physical Therapy, Las Vegas, NV, USA

Publication Information:

Physical Therapy in Sport 2012; 13: 123-133.

Background Information:

Low back pain (LBP) in athletes is very common. Treatment approaches typically focus on correcting the pathological anatomy and biomechanics via manual, rehabilitative or surgical methods. It is commonly thought that a simple correction of the underlying pathology (if we can identify it) with a treatment (i.e. injection, surgery, manipulation or exercise) will result in elimination of the symptoms and restore normal function. However, as we are all aware, many patients that appear to have recovered from injury continue to experience pain. We should also remember that, ironically, many patients who have significant tissue pathology (arthritis, bulging discs etc.) experience little to no pain.

The authors of this paper propose that we take a more comprehensive biopsychosocial approach to treating LBP. This model encompasses more than simply biological factors related to human functioning, by addressing the psychological (thoughts, emotions and behaviors), and social (work and playing status, culture and religion) factors which are known to influence athletic functioning in the context of injury or illness. This includes developing a greater understanding of how the nervous system processes injury, disease, pain and emotions.

Biopsychosocial Approach:

Anatomical Model:

Obviously, anatomy remains a cornerstone of manual medicine practice. In fact, we as clinicians often use anatomy to explain pain to our patients. A proper understanding of the anatomical structures will help the patient understand why he/she may be experiencing pain. However, as we now know, this model has a limited ability to explain persistent pain, widespread pain or pain driven by fear and emotion.

Biomechanical Model:

Analyzing movements and determining discrepancies between normal movement patterns versus abnormal patterns are also essential to manual therapy – particularly in fine-tuned athletes. A clinician is expected to be able to pinpoint minor biomechanical alterations which can have profound implications for high level performance. This model has limitations in explaining persistent and widespread pain as well, especially if the biomechanical abnormality has been corrected or significantly improved.

Tissue Pathology:

The tissue pathology model, similar to the anatomical model, is valuable for explaining acute pain. However, if tissues have healed but pain persists, clinicians that rely on this model alone may struggle to explain persistent pain to their patients.

Pain Mechanisms:

The pain mechanism model, in addition to the previous 3 models, provides an increased understanding of the nervous system’s processing of an athlete’s LBP. For discussion purposes, the pain mechanism model can be divided into three overlapping processes of input, processing and output.

1) Input Dominant Mechanisms

Tissue injuries occur in various environments. Studies have demonstrated that the environment can alter the perception of the injury or threat the injury represents. It has also been shown that an injury in a stressful environment is linked to poor outcomes. Therefore, clinicians need to understand the broader environment when assessing an athlete with low back pain (i.e. playing status, importance of a game, position on the team etc.).

The delivery of the information from the tissue to the spinal cord and brain via electrochemical communication is also an important input dominant mechanism. The peripheral nervous system and spinal cord provide nociceptive input, mainly via C-fibers and A-delta fibers from the affected area (the low back, for example), which are sent via the dorsal horn of the spinal cord to the brain for further processing. Injury will cause the nervous system in and around the affected area to become hyper-excitable; referred to as peripheral nerve sensitization. Although the athlete may have healed, the nervous system may have an increased sensitivity, resulting in persistent symptoms.

Clinically, these patients will have heightened responses to stimuli, including palpation of the peripheral nerves, along with active and passive neurodynamic testing such as the straight leg raise and slump test.

2) Processing Dominant Mechanisms

In processing dominant systems (central sensitization), the spinal cord, brain stem and cerebral hemispheres become the source of dysfunction, with or without peripheral input. The CNS, due to persistent input (particularly via C-fibers) increases its sensitivity over time. This is considered a ‘plastic’ change to the nervous system. The pain becomes more widespread and affects areas other than the original area of the injury. Pain is now heavily affected by thoughts, feelings and emotions.

3) Output Dominant Mechanisms

Persistent pain, failed treatments, multiple diagnoses and opinions, decreased coping skills and increased fear can affect various output mechanisms. Changes associated with these output mechanisms include decreased blood flow to muscles, endocrine changes such as altered cortisol production, muscle fiber adaptations in stabilizing muscles of the spine including atrophy and altered recruitment patterns, sympathetic nervous system changes associated with increased nerve sensitivity, changes in pain modulation with increased sensitivity, and changes in breathing, mood and possibly performance.

Representation:

The representation model of pain takes on the brain and its processing of pain. Functional MRI and positron emission tomography scans have allowed scientists to show that when the brain processes information from the tissues, numerous areas are activated to deal with the threat of an injury, disease or situation. These commonly ignited areas generate a ‘pain map’, which is referred to as a neural signature, neuromatrix or neurotag. The neural signature is not dependent on any specific tissue (i.e. disc, facet or nerve), but rather the impending threat itself. ‘Emotional pain’ uses similar areas to ‘physical pain’ – we now know this. It is important to understand that each person’s neuromatrix is individualized, which further underscores the importance of one-on-one, specialized pain education sessions (versus programs designed for groups of patients). Pain is an output and ultimately a conscious decision by the brain, based on the sum of all the information it receives from the tissues and surrounding environment. Any time the neural signature of LBP is activated the map activates and may produce pain. Maps related to beliefs, knowledge/logic, other sensory cues and social issues can also activate the neural signature and produce pain. LBP associated with a potentially career-ending injury is a good example of a belief that can activate the neural signature and provoke pain in the athlete with no obvious structural problem.

Evolutionary Biology:

It has been proposed that a true biopsychosocial approach incorporate a viewpoint of pain from an evolutionary model. Pain, although often unpleasant, is an important part of life and survival. Processes such as neuronal death, neuroplasticity and receptor field changes and expansion (spreading pain) can be seen as processes aimed at survival through evolutionary biology.

Psychosocial Issues:

Pain may have many layers, otherwise known as the onion skins model (2). An athlete may have nociception (tissue injury), yet it may be modulated by issues such as attitudes and beliefs, suffering, pain escape behaviors and more.

Fear Avoidance:

It has been stated that “the fear of pain may be worse than pain itself”. Anyone who has treated a chronic pain population will attest to the truth of this statement. The unknowns with LBP (i.e. recovery time, return to sport, diagnosis etc.) can affect the athlete and may present itself as increased fear and pain.

The Neuromatrix, Athletes and Performance:

Sports performance is an output of the brain. Through repetition and practice, athletes strengthen neural pathways – optimizing synaptic activation – and develop ‘sports skills’ maps in their brains. This same process occurs in patients with pain, but in a negative way. Changing pain is often difficult because patients who continue to experience their pain are essentially facilitating (or cementing) the pain pathways through repeated activation/release of neurotransmitters such as dopamine. As noted in the previous section, many different influences may then activate the pain map. Once activated, the athlete’s optimal movement and performance will likely be adversely affected.

For optimal performance, all areas of the brain should function at optimal capacity. Certain areas of the brain are normally used to perform athletic skills. Now imagine, in an athletic population with LBP, these areas of the brain are used to process nociception as part of the pain experience, and therefore may not be able to provide an optimal output for performance.

One example used by the authors of this paper involves the pre-motor and motor areas. Motor control is significantly affected by fear of pain, anticipation of pain, catastrophization, past history of LBP and by thoughts and emotions. Clinically, we have all seen that pain can change motor control. The athlete that spends significant time preparing mentally and rehearsing techniques may indeed have their pre-motor area limited if it is actively contributing to a pain neuromatrix.

There is a significant amount of research to demonstrate that neuroscience education for the patient has been successful in treating chronic LBP, especially widespread pain. Can we directly infer that this would work with the competitive athlete, LBP and performance? The short answer is no. However, it would be safe to say that this evidence used in conjunction with clinical experience may be a helpful starting approach in tackling LBP in the athletic population.

Clinical Application & Conclusions:

Clinicians and therapists should continue to use their exercise and manual therapy in the treatment/rehabilitation process for the athlete with LBP. Manual therapy, including spinal manipulation, and segmental spinal stabilization exercises are part of the management of an athlete with LBP. However, the issues discussed in this paper speak to the complexity of LBP, including the psychosocial component of the athlete. Prime examples include the fear, anxiety and incorrect information about their own low back pain. The key is to systematically determine factors associated with the persistent pain and work towards addressing these problems. Systematically addressing each of the key components should, in theory, disengage parts of the ‘pain neuromatrix’. Neurofeedback and biofeedback are two of the many therapies available to help address the commonly missed components in the treatment of the athlete with LBP (1).

Educating the athlete about the neurobiology of their pain is vitally important towards the success of eliminating LBP. Explanation on the pain process is important but should not be bogged down by complex words (i.e. ‘rupture’) and anatomical pictures that may induce fear and anxiety. Each patient is unique, and will desire a different level of understanding. The goal is to calm the nervous system by addressing fears, expectations, anxiety and goals. Further, aerobic exercise can help manage the athlete’s pain, particularly if it is chronic, by increasing oxygen and blood to various tissues, decreasing nerve pain, improving sleep, improving mood and decreasing depression.

Study Strengths / Weaknesses:

Although the title refers to athletes, this paper discussed a variety of factors pertaining to LBP (and pain in general) that could apply to many patient populations. The discussion and evidence was fairly well laid out, with relevant applications for clinical practice. However, much of the research that was cited throughout the manuscript addresses LBP in the general population, or a chronic pain population. Careful interpretation is a must and no direct conclusions can be made from this type of work, especially if attempting to extrapolate to an athletic population. Having said that, their discussion was insightful and thought provoking which always makes for a good read!

Additional References:

  1. Sherlin LH, Larson NC, Sherlin RM. Developing a performance brain training™ approach for baseball: a process analysis with descriptive data. Appl Psychophysiol Biofeedback. 2013; 38(1): 29-44.
  2. Butler DS & Moseley L. Explain pain. Adelaide: Noigroup Publications (2003).