Neurobiology of disease
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Neurobiology of disease · Jan 1996
Cutaneous innervation density in the allodynic form of postherpetic neuralgia.
The relationship between deafferentation, sensory function, and pain was explored in 18 subjects with chronic postherpetic neuralgia (PHN). Subjective thresholds for warmth, cooling, and heat pain were measured quantitatively in painful skin areas and compared with normal contralateral skin. The severity of allodynia was graded in the affected area. ⋯ Immunofluorescence with the axonal marker PGP 9.5 revealed a reduction in density of innervation of the epidermis, the dermal-epidermal junction, and the eccrine sweat glands in PHN skin. In painful PHN skin, the reduction in innervation density was positively correlated with the magnitude of the thermal sensory deficits. However, 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 and allodynia.