September 2010 Newsletter from Malik Slosberg, DC, MS

Boudreau SA, Farina D, Falla D. The role of motor learning and neuroplasticity in designing rehabilitation approaches for musculoskeletal pain disorders. Manual Ther 2010; xxx: 1-5. Epub ahead of print.

Wand BM, et al. Cortical changes in chronic low back pain: Current state of the art and implications for clinical practice. Manual Therapy 2010;xxx:1-6. Epub ahead of print.
This month two articles concerning spinal problems and the brain are reviewed. Both of the studies are brand new. In fact, neither has yet been published in print but have been accepted for publication and are available online ahead of print. The first paper describes the changes in the sensory and motor cortex with injury/pain, as well as, with motor-skill training and the correlations between changes in brain maps and motor function. This is cutting-edge stuff, the forefront of understanding the effects of pain and motor-skill training on the brain and neuroplasticity. The second paper reviews the accumulation of research in the past decade which documents the neurodegeneration in the brain associated specifically with chronic back pain. It explains how central sensitization occurs and the impact on memory and cognitive function of chronic pain. Clearly, early management is important in preventing such impairment from occurring. Hope you enjoy and find this informative and helpful.

Boudreau SA, Farina D, Falla D. The role of motor learning and neuroplasticity in designing rehabilitation approaches for musculoskeletal pain disorders. Manual Ther 2010; xxx: 1-5. Epub ahead of print.

Cortical neuroplasticity or reorganization is an intrinsic, dynamic neurophysiological feature throughout life defined as morphological or functional changes in neuronal properties:
A. A change in strength of internal/synaptic connections,
B. Altered representational patterns in the sensory &/or motor cortex of a muscle, region, or limb,
C. A reorganization of neuronal territories (maps).

Cortical neuroplastic changes occur in association with experimental acute or chronic pain, as well as, with novel motor-skill training in rehabilitation of neurological or musculoskeletal pain patients. Cortical neuroplastic changes are also associated with changes in motor function such as improved motor skills following novel motor-skill training or disturbed motor patterns in the presence of experimental or chronic pain.

The representation of muscles affected by pain is altered in the sensorimotor system. The extent of the cortical neuroplastic changes is correlated with the level of motor function/deficit.
Importantly, the level of ongoing pain and the associated cortical neuroplastic changes may be reversed by sensory & motor task training. Motor training can reduce the extent of cortical neuroplastic changes associated with pain. Changes in cortical excitability and reorganization as a result of novel motor-skill training occur rapidly, and continually evolve with extended training. These changes are associated with an increased motor representation and excitability of the trained muscles.

Skilled or precision functional tasks facilitate cortical neuroplastic changes and lead to improvements in motor behavior/performance. An effective approach for musculoskeletal pain involves training the activation of a delayed/inhibited muscle with repeated isolated voluntary contractions. Strength training doesn’t achieve the same effect as motor-skill training. The ability to target specific components of movement requires greater skill and increased levels of attention and precision than contraction of all muscles as in strength training. Slowly increasing the complexity of a novel motor-skill task over the course of rehab training encourages cognitive effort and enhanced cortical neuroplastic changes with novel motor-skill acquisition. Novel motor-skill training should be advocated to reduce the risk of unfavorable neuroplastic changes that occur in association with pain.

Pain can hinder the cortical neuroplastic changes associated with novel motor-skill acquisition. Acute experimental pain suppresses the rapid increases in cortical excitability of the primary motor cortex with training and interferes with the incremental gains in task performance. These findings suggest that motor-skill training should be performed in a pain-free manner in order to optimize success.

Commentary: This new article published online but not yet in print demonstrates the far-reaching changes in the brain that occur with injury/pain and motor-skill training. It is now well documented that reorganization of sensory and motor cortical maps occur with pain and are associated with changes in strength, endurance, motor control, range of motion, and sensory responses to subsequent normal and noxious stimuli. Furthermore, there is evidence that motor-skill training which involves more precision, necessitates more motor-learning than strength exercises, and requires more cortical effort enhances reorganization in the brain and is documented to help normalize sensory and motor cortical maps. This is exciting stuff for clinicians because it indicates the profound and far-reaching impact of motor-skill training on the brain, motor function, and reductions in pain. This review also emphasizes that such training should be performed after the acute phase of pain has ended because pain hinders the positive changes in the brain from occurring with motor-skill training. It is best to begin motor-skill training once the patient is beyond the acute phase. Just a note, a series of studies by Heid Haavik-Taylor, DC, PHD & Bernadette Murphy, DC, PhD have demonstrated that spinal manipulation to dysfunctional cervical joints may improve and help normalize sensory and motor cortex function chronic neck pain patients at least in the short-term!

Wand BM, et al. Cortical changes in chronic low back pain: Current state of the art and implications for clinical practice. Manual Therapy 2010;xxx:1-6. Epub ahead of print.
There is increasing evidence that chronic pain problems including chronic back pain (CBP) are characterized by alterations in brain structure & function. There is also a growing sense that these brain changes contribute to CBP. The brain changes can be categorized as neurochemical, structural or functional.

A method to compare the volume of gray & white matter in specific brain areas, provides compelling evidence of reduced gray matter in the dorsal lateral prefrontal cortex, right anterior thalamus, brainstem, somatosensory cortex & posterior parietal cortex of people w CBP. There are strong correlations between the extent of density changes and pain intensity & unpleasantness. There seems to be fewer brain cells in these areas with CBP.

In the primary somatosensory cortex,the representation of the lower back is expanded & shifted medially invading the area where the leg is normally represented. The extent of expansion is closely associated with pain chronicity. Studies also suggest that CBP is characterized by enhanced cortical responses to noxious stimulation and activation of a more expansive network of pain-related brain regions with peripheral noxious input. In addition, CLBP Pts have lower increases in blood flow in the periaqueductal gray, an important part of the descending antinociception system, when exposed to painful stimuli. These brain changes likely sensitize neural networks that subserve nociception and pain.
Unfortunately, brain areas that demonstrate neurodegeneration are known to be involved in antinociception, as are those that demonstrate reduced activation during noxious stimuli and spontaneous pain.

Furthermore, shifts in primary motor cortex representation have been reported with CBP: the motor cortical representation of contraction of the transversus abdominis muscle was shifted and enlarged with recurrent LBP. Raised motor thresholds have also been reported for lumbar back muscles with CBP, which suggest decreased corticospinal drive to these muscles, that some degree of inhibition of stabilizing paraspinal muscles, such as the deep multifidi.

Perhaps, even more disturbing is the finding that differences in the “resting” brain have also been reported raising the possibility that brain activity is different in CBP even when the brain is not involved in processing noxious input. CBP patients are impaired on a task designed to assess emotional decision making. Performance was negatively related to pain intensity. Significant impairments in memory, language skills, mental flexibility, as well as, deficits in cognitive function, changes in decision making and appraisal have also been noted in CBP patients.

Commentary: This unsettling paper is an excellent summary of a decade of research which documents that chronic pain of many varieties, but specifically chronic back pain has deleterious effects on brain organization, excitability, antinociception pathways, motor control, and even on non-pain or motor related functions such as decision making, memory, language skills, and cognitive skills. This avenue of research helps us, as clinicians, to understand the dramatic impact of chronic pain on the brain and allows us to focus on minimizing chronic pain with the use of effective early interventions, such as the combination of manipulation or mobilization with exercise. You may recall from another 2010 article I reviewed that manipulation or mobilization significantly improves the pain relief achieved by exercise training and exercise training in addition to manipulation and/or mobilization significantly improves pain, function, quality of life and patient satisfaction when compared to manipulation or mobilization alone over the long-term. Equipped with this knowledge, chiropractors can provide the best opportunity to manage the acute patient well and minimize chronic pain and function, as well as, the neurodegeneration which occurs with chronic pain.