Persistent Low Back Pain, the Brain, and Motor Control
I chose this topic because it is by far the most common chronic injury that I encounter. It is also the subject of much debate throughout the medical community, as well as the topic of the latest issue of the Journal of Orthopedic and Sports Physical Therapy (JOSPT; June 2019).
Low back pain is the leading cause of activity limitation and work absence throughout much of the world and is associated with an enormous economic burden. And yet, we still don’t really know what causes it.
From a previous JOSPT issue in 2012 on how we manage low back pains as physical therapists, here is what we know: Females have a higher prevalence, and back pain of higher intensity increases with age. Age may cause us to feel more back pain due to weaker muscles and stiffer joints. Risk factors for low back pain include increased time sitting, poor physical condition, and improper bending and lifting. And like most ailments, stress and lack of sleep can make it worse. None of that is probably all that surprising though.
What is perhaps more surprising is that research shows that psychological, social, and lifestyle factors likely play a bigger role in back pain than physical factors.
Let’s explore “physical factors” first. We know that pain can originate from any number of structures that have nerve endings (including muscle, ligaments, connective tissue around the spinal cord, intervertebral discs, nerve roots, and the vertebrae themselves) but when we try to identify particular structures that cause certain types of back pain, we come up with guesses that equate to less than 50% accuracy. So, worse than a guess. Savage et al reported that 32% of their participants without back pain had an “abnormal” image, and only 47% of those that were experiencing low back pain had an abnormality identified. It is difficult to determine diagnosis based on anatomy alone due to a high rate of these “false positives” of MRIs on individuals with abnormal MRI’s but no symptoms. One study found that herniated discs are present in 75% individuals without corresponding symptoms. What else could be going on then here if it is not purely- or mostly- anatomical?
To understand the psychological, social and lifestyle factors, it is important to understand that low back pain is complex and involves not just mechanical factors (i.e. damaged and/or overloaded tissue), but also changes within the nervous system. Each individual with chronic low back pain will likely be influenced by a combination, with no two alike. Although there is much debate about the causes of and solutions for low back pain, what is generally agreed upon is that the motor control is invariably altered in the presence of pain. "Motor control" refers to the way that the nervous system and muscles work together to control posture and create movement. In the presence of pain, we move differently, which can certainly create long-term problems for our bodies and minds.
The interplay of the mind and the body is complex. As a medical community, we are constantly learning, through inquiry and research, about how to help people manage these systems. Neuroplasticity, defined as the ability of the nervous system to undergo change, is particularly relevant when considering pain and injury. Chemical changes occur in both the brain and the body with chronic low back pain, and we are learning how this can have long-term positive and negative influence.
If you have low back pain and want to learn more about how these factors might be at play in your unique case, consider talking with a physical therapist. Research shows motor control training can lead to changes in the brain that support painfree movement. Aerobic exercise is also suggested to play a vital role in regulating brain and body processes involved with pain reduction.
Take home message: Low Back Pain is complex. Exercise is key, and movement is healthy, but it is important to learn the right balance. It is also key to address any sources of stress in your life that may be contributing to a sensitized nervous system if your pain is recurring or chronic.