Clinically Reducing/Eliminating Chronic Neuropathic Pain by Bridging Peripheral Nerve Gaps with an Autograft within a PRP-Filled Collagen Tube.

Purpose: Peripheral nerve trauma is associated with 50-79% of individuals developing chronic neuropathic pain. No technique reliably induces long-term chronic neuropathic pain reduction/elimination.

Patients and methods: This study compared the influence of bridging peripheral nerve gaps with an autograft vs an autograft within a platelet-rich plasma- (PRP) filled collagen tube (PRP repair) on the level of long-term chronic neuropathic pain.

Results: Pre-surgery, all 11 autograft repair subjects suffered chronic neuropathic pain of 4-10 (mean 8.6±4.2), with 81.8% of 8-10. Following repairs, pain reduction started when axons started reinnervating targets. The pain decreased to 0-6 (mean 0.27 ± 0.3), with 18.2% having long-term pain reduction and 81.8% long-term pain elimination. Pre-surgery, of the 15 PRP repair subjects, 60% suffered chronic pain of 4-10 (mean 7.7 ± 1.4), with 66.7% pain of 8-10. Pain reduction began within two weeks, and within two months, 11% of the subjects had maximum pain reduction and 89% long-term pain elimination. The pain never increased or occurred over the following 1.1-15.4 years.

Conclusion: Chronic neuropathic pain is normally reduced/eliminated when axons reinnervate targets, including by using targeted muscle reinnervation (TMR). However, bridging nerve gaps with an autograft within a PRP-filled collagen tube reduces/eliminates pain far faster because axon regeneration and target reinnervation are not required, only that platelet-released factors act on the peripheral axons. In addition, the PRP technique induces pain reduction several times greater than TMR, and although TMR is only effective when applied less than four months post-trauma, PRP is effective when applied at least up to 3.25 years post-trauma. This is the first clinical demonstration that PRP induces long-term pain reduction/elimination by factors acting only on peripheral axons, while they are regenerating and does not require target reinnervation. This study sets the stage for testing whether bridging gaps with only a PRP-filled collagen tube has the same effects.