Post-herpetic neuralgia: post-mortem analysis of a case.
The morphological and biochemical substrates of the severe pain in post-herpetic neuralgia (PHN) are unclear. This report is an autopsy study of a 67-year-old male with severe PHN during the last 5 years of his life over the right T7-8 dermatomes. The dorsal horn of the thoracic spinal cord of the affected side was atrophic from T4 to T8, with loss of both myelin and axons. Despite this, only the T8 ganglion was affected by fibrosis and cell loss and only the nerve roots at that level appeared affected. Markers of unmyelinated afferents (substance P), substantia gelatinosa neurons (opiate receptors), glial cells (glial fibrillary acidic protein), and descending spinal projections (dopamine-beta-hydroxylase and serotonin) were not different at affected versus non-affected spinal cord levels. The pain of PHN may result from the uninhibited activity of unmyelinated primary afferents as a result of the loss of myelinated afferent fibers and the possible presence of hypersensitive neurons in the dorsal horn.
Watson
C P N
CPN
Irene Eleanor Smythe Pain Clinic, Toronto General Hospital, Toronto, Ont. M5G 2C4 Canada Neurobiology Research Group, Department of Anatomy, University of Toronto, Toronto, Ont. M5S 1A8 Canada.
Morshead
C
C
Van der Kooy
D
D
Deck
J
J
Evans
R J
RJ
D000368:Aged; D001284:Atrophy; D005727:Ganglia, Spinal / Q000473:pathology; D006562:Herpes Zoster / Q000150:complications* / Q000473:pathology; D006801:Humans; D008297:Male; D009413:Nerve Fibers, Myelinated / Q000473:pathology; D009437:Neuralgia / Q000150:complications / Q000382:microbiology / Q000473:pathology*; D010146:Pain / Q000209:etiology* / Q000382:microbiology / Q000473:pathology; D013116:Spinal Cord / Q000473:pathology*