(424) Cross-linked hyaluronic acid in the treatment of lower extremity neuropathic pain

Abstract

Persistent neuropathic pain presents a special challenge to the clinician as current treatment regimens include opioids, anti-neuropathic adjuvants and nerve blocks provide only modest pain control, and are hindered by dose limiting side effects. While the literature describes the use of cross-linked hyaluronic (CL-HA) acid as a dermal filler, our aim is to assess its safety and efficacy in treating lower extremity neuropathic pain. A 36-month retrospective chart review revealed: 11 patients (4 female/7 male); Average: Pain duration-79.5 mos. (4-240); Age-54.7 yrs. (27-82). Patients underwent targeted, neural matrix antinociception injection of CL-HA: Buttocks, 1 (9%); Thigh, 1 (9%); Feet, 9 (82%). Patients approved and consented to the use of their clinical data. FDA approved CL-HA dermal filler agents use was off-label. Average: Dose given-0.15 cc (0.05-0.2); Time to relief-24 hrs. (0-48); Relief duration-11.7 mos. (2.5 -24); VAPS-1.5/10 (0-3.5); Untoward effects: 0; Results assessed by degree and duration of pain relief from a single injection. Mechanisms underlying these findings are likely multifactorial and require additional study include: 1. CL-HA as a physical, protective shielding and compartment: Blunting activation of spontaneous activity in: C-fiber and Remak bundle afferency, and aberrant nociceptive ephapse; 2. CL-HA anionic depolarization: Polyanionic nature results in a sustained action potential refractory state; 3. CL-HA LMW/HMW-HA mismatch correction and ICAM-1 inflammatory modulation. This results in TSG-6 modulation of the regional, inflammatory activation, thereby permitting CD44/RHAMM interactions to proceed with HMW-HA, stabilizing and restoring the extracellular neural matrix (ECNM) post-injury, immuno-neural cross-talk dysregulation at the level of the ECNM, which resulted in the chronification of pain in the first place. We conclude that targeted, neural matrix antinociception injection of CL-HA is a safe and effective method of treating lower extremity neuropathic pain. Its routine use should be considered early in the treatment of this patient group.