Peripheral Nerve Entrapment: Pathophysiology
Non-pharmacological therapeutic interventions are being embraced by the medical community because they are simple to carry out, economical, and have relatively minor side effects. One treatment approach that can be used as part of an individualized multi-modal program to manage persistent pain is neural mobilizations.
In the book Clinical Neurodynamics, physiotherapist Michael Shacklock provides some insight into how mechanical irritation may lead to localized nerve inflammation.
As peripheral nerves pass through the body they may be exposed to mechanical or chemical irritation at different anatomical points. Prolonged compression or fixation of a nerve may result in a reduction of intraneural blood flow. This then triggers the release of pro-inflammatory substances (calcitonin gene-related peptide and substance P) from the nerve. This is referred to as neurogenic inflammation and it can disrupt the normal function of nerves even without overt nerve damage, it can also contribute to the initiation and propagation of chronic pain.
In these cases five minutes of passive mobilization may help to diminish intraneural edema and/or pressure (Boudier-Revéret et al. 2017). This will have a modulatory affect on peripheral and central processes.
In longer standing cases the development of fibrosis, may contribute to peripheral nerve dysfunction. Geoffrey Bove has investigated how trauma and ongoing inflammation can be a contributing factor to connective tissue changes (increased collagen and TGF-β1 deposition). This process has been described as a progression from densification (alterations of loose connective tissue) to fibrosis (alterations of collagen fibrous bundles).
Functionally, these changes may influence biomechanical properties secondary to tissue adherence or tethering structures to each other. It may also induce chronic compression of peripheral nerves (ie. carpal tunnel syndrome, hamstring syndrome, meralgia paresthetica, infrapatellar syndrome etc...). If implemented early the application manual therapy that may attenuate tissue fibrosis and restore motility of peripheral nerves (Bove et al. 2016 & Bove et al. 2019).
Does Neural Mobilization Work?
There is a fair bit of research to support the use of nerve mobilizations for musculoskeletal pain. The most recent meta-analysis on the topic was published in The Journal of Orthopaedic & Sports Physical Therapy. This study suggests that nerve mobilizations are useful for patients with back, neck and foot pain (Basson et al. 2017).
In terms of mechanism of action, the underlying effects of neural mobilization are complex and multifactorial. In addition to endogenous pain modulation, soft tissue mobilization may help diminish intraneural edema and expedite clearance of pro-inflammatory cytokines. Additionally, an interesting area of research is to what degree can soft tissue mobilization mitigate the development of post-inflammatory connective tissue fibrosis, and how does this effect epineurial and perineurial structures.
Then if massage therapy is applied with an optimized dosage, what are the implications for patients with repetitive strain disorders or peripheral neuropathy.
More to Explore
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