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KMID : 0376219840210030561
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Chonnam Medical Journal
1984 Volume.21 No. 3 p.561 ~ p.581
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An Electron Microscopic Study on Traumatic Neuroma
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Abstract
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The morphologic description about traumatic neuroma is largely limited to human biopsy cases and to the distal area, so that no time-sequential changes are described and the findings in the proximal area adjacent to normal nerve tissue are not clearly defined. The reports of Schwann cell proliferation, but no regeneration of nerve fasciculi in the crushed peripheral nerves may suggest a morphologic heterogeneity in traumatic neuromas, because the prominent early changes in the crushed or severed nerves are the same Wallerian degeneration. Though severance of the nerve may be different from crush injury in its extent, Schwann cell proliferation in the proximal area of the traumatic neuromas is expected in addition to topographical differences between the proximal and distal areas.
The sciatic nerve of adult male rats was severed and the proximal ends were observed light and electron microscopically 2, 4, 8, and 16 weeks after severance. The results were as follows.
1. The traumatic neuromas were fusiform and had no clear demarcation from the surrounding soft tissue. They consisted of proximal cellular area where the cells were arranged haphazardly and distal area where regenerative nerve fasciculi were the dominant structures, regardless of the observation period. The differences by the observation period are size of the traumatic neuromas, and degree of cellularity and Wallerian degeneration.
2. In the proximal area, the predominant cells were Schwann cells, and occasionally perineurial cells and fibroblasts present. They were noted individually or axon-Schwann cells and perineurial cells formed nerve fasciculi which were barely discernible light microscopically.
3. In the distal area, the nerve fasciculi, axon-Schwann cell units surrounded by perineurial cells, invaded the neighboring connective tissue and skeletal muscle tissue, which caused atrophy of the muscle fibers. In the peripheral zone of the distal area, free axon sprouts or Schwann cells were occasionally noted.
4. The myelin sheaths formed in regenerative nerve fasciculi were much smaller than those in normal nerve tissue.
From these results, it is concluded that traumatic neuromas have different morphological findings relative to the topographical ar`as rather than to the observation period. Also concluded that the difference may reflect the direct response of Schwann cells to an injury and subsequent regenerative reaction of nerve tissue.
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