Macrophages of CNS and DRG in Postherpetic Neuralgia: From Pathobiology to Therapeutic Frontiers.

Abstract

Background: Postherpetic neuralgia (PHN), the most common complication of herpes zoster (HZ), is a type of neuropathic pain. Described as the presence of chronic, persistent, debilitating pain, PHN impairs patients' quality of life significantly. Currently, numerous clinical interventions for PHN have been developed, each demonstrating various curative effects. However, these interventions are often accompanied by limitations such as high recurrence rates and inconsistent therapeutic outcomes. Further efforts are still needed to explore effective treatments for PHN.

Objective: Our aim was to provide a comprehensive review of the latest research findings on the mechanism of the macrophages of the central nervous system (CNS) and dorsal root ganglion (DRG) in PHN. We focused on the symptomatic and etiological treatments of PHN.

Study design: A narrative review.

Methods: We searched PubMed for all articles on macrophage-related mechanisms in the CNS and DRG in cases of PHN, as well as all literature on PHN treatment strategies, with a focus on therapeutic measures that targeted neural inflammation and injury.

Results: Microglial activation in the spinal dorsal horn (SDH) and macrophage expansion in the DRG are major mechanisms underlying PHN. The therapeutic strategies for managing PHN include symptomatic and etiological treatments. The former involve medications, nerve blocks, and neuromodulation. The latter, meanwhile, focus on autologous biomaterials, such as autologous fat, bone-marrow aspirate concentrate (BMAC), autologous plasma, and serum, which specifically target neural inflammation and injury.

Limitations: Therapeutic interventions for PHN, especially those employing autologous biomaterials, are still lacking multicenter, large-sample, high-quality studies to provide robust evidence and guide clinical application of the treatments.

Conclusion: Patients with PHN, especially those with refractory pain, endure profound and unremitting suffering. Therefore, the quest for interventions that can achieve stable and substantial improvements in patients' conditions is both urgent and of critical clinical importance.