Postherpetic Neuralgia: Irritable Nociceptors and Deafferentation

@article{Fields1998PostherpeticNI,
  title={Postherpetic Neuralgia: Irritable Nociceptors and Deafferentation},
  author={Howard L Fields and Michael C. Rowbotham and Ralf Baron},
  journal={Neurobiology of Disease},
  year={1998},
  volume={5},
  pages={209-227}
}
Postherpetic neuralgia (PHN) is a common and often devastatingly painful condition. It is also one of the most extensively investigated of the neuropathic pains. Patients with PHN have been studied using quantitative testing of primary afferent function, skin biopsies, and controlled treatment trials. Together with insights drawn from an extensive and growing literature on experimental models of neuropathic pain these patient studies have provided a preliminary glimpse of the pain-generating… 
94 – Postherpetic Neuralgia
Postherpetic neuralgia: Topical lidocaine is effective in nociceptor–deprived skin
TLDR
Topical lidocaine is effective in postherpetic neuralgia (PHN) even if the skin was completely deprived of nociceptor–deprived skin, and subgroup analysis revealed that patients with impairment of nOCICEptor function had significantly greater pain reduction under lidocane vs placebo.
Post-herpetic Neuralgia: a Review
Post-herpetic neuralgia (PHN) is a chronic neuropathic pain condition that persists 3 months or more following an outbreak of shingles. Shingles, also known as acute herpes zoster, is associated with
Allodynic skin in post‐herpetic neuralgia: Histological correlates
TLDR
The present study further indicates peripheral nervous system involvement in PHN but does not support a direct correlation between epidermal innervation changes and tactile allodynia.
[Postherpetic neuralgia].
TLDR
Systematic reviews of data from clinical trials of drug therapy for PHN have given distinct indications for antidepressants, antiepileptics, opioid analgesics and topically acting agents.
Pathophysiology of pain in postherpetic neuralgia: A clinical and neurophysiological study
Peripheral nociceptor sensitization mediates allodynia in patients with distal symmetric polyneuropathy
TLDR
The lack of difference in NCS data between patients with and without allodynia suggest that this type of pain, rather than arising through second-order nociceptive neuron sensitization to Aβ-fibre input, might reflect a reduced mechanical threshold in sensitised intraepidermal nocICEptive nerve terminals.
Postherpetic neuralgia: epidemiology, pathophysiology and management
TLDR
The incidence of HZ, and therefore that of PHN, is likely to increase as a result of greater longevity and increasing numbers of patients receiving treatment that compromises cell-mediated immunity.
Reappraising neuropathic pain in humans—how symptoms help disclose mechanisms
TLDR
It is proposed that the emerging mechanism-based approach to the study of neuropathic pain might aid the tailoring of therapy to the individual patient, and could be useful for drug development.
...
...

References

SHOWING 1-10 OF 167 REFERENCES
Nociceptor modulated central sensitization causes mechanical hyperalgesia in acute chemogenic and chronic neuropathic pain.
TLDR
The principle finding of these experiments is that the severity of brush-evoked pain correlates with the intensity of background pain in patients suffering from chronic painful neuropathies and in normal subjects with acute experimental chemogenic pain.
Cutaneous Innervation Density in the Allodynic Form of Postherpetic Neuralgia
TLDR
The relationship between deafferentation, sensory function, and pain was explored in 18 subjects with chronic postherpetic neuralgia and loss of cutaneous innervation was inversely correlated with allodynia, indicating that surviving cutaneous primary afferent nociceptors that are spontaneously active and/or sensitized contribute to PHN pain andallodynia.
Postherpetic neuralgia. Are C-nociceptors involved in signalling and maintenance of tactile allodynia?
TLDR
It is concluded that sensitized nociceptive C-fibres are not involved in signalling allodynia, and changes in CNS processing may occur after zoster infection that strengthen the synaptic ties between central pain signalling pathways and low-threshold mechanoreceptors with A beta- fibres.
Somatosensory findings in postherpetic neuralgia.
TLDR
It is suggested that if PHN does not occur following acute herpes zoster, recovery of neural functions appears to be good and major central involvement in the pathophysiology of the condition is suggested.
Mechanical allodynia in postherpetic neuralgia
TLDR
It is demonstrated that sensitized nociceptive C-fibers are not involved in signaling and maintenance of allodynia, and Alteration in CNS processing may reorganize synaptic ties between central pain-signaling pathways and mechanoreceptive A beta -fiber depending on afferent C- fiber degeneration rather than ongoing C-Fiber input.
Topical Capsaicin
TLDR
Overall, the clinical studies showed mean reductions of VAS scores for pain intensity following capsaicin therapy in 21 to 39%, 16 to 49% and 28 to 55%, respectively, of patients with post-herpetic neuralgia, diabetic neuropathy and osteoarthritis, where the pain can be chronic and difficult to treat.
...
...