Understanding causation goes hand in hand with “mechanisms” in Motor Behavior Therapy. Scapular winging is a common finding in shoulder related symptoms (and neck too!). This is believed to be involved in loading tissues in the shoulder region.
When assessing movement pattern control in the shoulder girdle and true winging is seen (not tipping of the scapula), it should not be assumed that the cause of this is weakness of serratus anterior.
There is a need for a philosophical discussion about what actually constitutes the physical finding of what clinician’s consider “weakness”. This is largely based on reduced force production ability compared to some reference standard.
- At rest, how does this “weakness” manifest?
- Is it really “weakness” if there is low tone with a postural load (e.g., four point kneeling)?
- Is it really “weakness” force can be generated at higher loads, but there is low tone at rest?
This is a much larger discussion (paper in progress!). For the purpose of this blog, I just wanted to highlight the importance of the neurodevelopmental process (e.g., postural reflexes) in the development of and muscle tone and “strength”.
There are some postural reflexes that are important in developing tone around the shoulder girdle (e.g., prone rolling, crawling). Taking a birth history can often reveal gaps in the neurodevelopmental process.
If the central nervous system does not learn to adequately fix the scapula on the chest wall during open and closed chain movements during the neurodevelopmental process, should we expect high load exercises to replace this gap in development?
The failure to address the causation involved in the mechanism(s) may increase the likelihood of:
- poor response to the intervention
- slow progression of rehabilitation
- sooner recurrence
Looking only at the ability to produce force against external resistance is a common clinical assessment technique. Many aggravating factors related to shoulder girdle pain are based on low load or postural load.
We must question if it is functional to only consider assessments based on external load – beyond functional loads.
There is a need for a broader clinical reasoning framework. This should consider
- “why are the central and peripheral nervous systems not producing enough stiffness at low load (or too much stiffness)
- “why are the central and peripheral nervous systems not producing sufficient force to meet the reference standard we are using”?
This is a much larger discussion, however neurological dysregulation should be part of it. Of this, reduced postural reflexes should be considered.
Summary
Understanding the causation of the movement pattern control deficit is a key aspect of rehabilitation. Neurological dysregulation is not a well recognized mechanism in musculoskeletal pain, but should be considered. The neurodevelopmental process is important in developing normal movement pattern control. Reduced postural reflexes are common and can influence rehabilitation utilizing movement and motor behavior. We must understand the mechanisms and causes by which a patient presents with “weakness”. Surely, neurological dysregulation should be considered.
Postural reflex facilitation techniques are easy to use strategies to improve muscle tone, movement and motor behavior.
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