Does varicella-zoster virus reactivation injure sensory ganglia and peripheral nerves and cause persistent inflammation and neuropathic pain after shingles?

Herpes zoster reflects reactivation of varicella-zoster virus (VZV) in sensory ganglia. In an 83-year-old, the clinical relevance is substantial because zoster-associated neural injury can evolve into postherpetic neuralgia (PHN), commonly defined as dermatomal neuropathic pain persisting ≥90 days after rash onset.

Neural injury and pain

• Human neuropathology strongly supports injury centered in dorsal-root or cranial sensory ganglia, with extension through sensory roots and peripheral axons. Reported findings include ganglionitis, neuritis, inflammatory infiltrates, hemorrhagic necrosis, demyelination, sensory-root degeneration, axonal loss, and ganglion-cell loss.
• This injury provides a well-established basis for persistent neuropathic pain after shingles. Damaged sensory neurons and axons can develop ectopic firing and lowered activation thresholds, producing peripheral sensitization, allodynia, and pain. Deafferentation and central sensitization may further sustain symptoms after the rash resolves.
• Experimental human dorsal-root-ganglion models support biological plausibility: VZV infects neurons and satellite cells, causes cytopathic remodeling, and impairs neuronal viability or function. Both direct virus-associated damage and immune-mediated injury may contribute.

Persistent inflammation

• Persistent local immune activity is biologically credible: CD8+ T-cell infiltrates and VZV DNA have been identified in sensory ganglia years after zoster. PHN cohorts also show associations between pain or PHN occurrence and cytokine abnormalities, including IL-10, IL-6, TNF-alpha, and CRP.
• These observations do not establish persistent inflammation as the independent cause of chronic pain. Such markers may accompany residual nerve injury or latent viral material rather than demonstrate ongoing viral replication or a direct inflammation-to-pain pathway.

Bottom line

• VZV reactivation clearly injures sensory ganglia and sensory pathways and is a well-supported cause of post-shingles neuropathic pain through nerve damage and sensitization. Persistent inflammation is a plausible contributor, but its relative importance versus lasting neural injury remains uncertain.