REGENERATION AT THE PREDILECTIVE DAMAGE SITES OF NERVE TRUNKS IN TREATED LEPROSY

Superficially located large and medium sized mixed peripheral limb ner ves in active leprosy have previously been shown to have well-recogniz ed fusiform swellings. It is generally agreed that these are the sites of predilective nerve involvement where the severest degeneration and fibrosis occur. A semiquantitative histopathological study on one of these sites, the flexor retinaculum region of the posterior tibial ner ve, has been carried out on 14 treated leprosy patients who suffered f rom total sensory loss to the foot for between 2 and 40 years. The fol lowing observations were made: (1) large-scale nerve regeneration was present as characterized by numerous Schwann cells and unmyelinated ax ons which formed regeneration clusters; (2) thick myelinated axons wer e either absent or present only in very low numbers; (3) the intraneur ial fibrosis was usually not severe; (4) the presence of active inflam mation probably interfered with nerve regeneration; (5) it appeared th at this regeneration started shortly after the onset of therapy and pe rsisted for decades; (6) lepromatous cases were characterized by evenl y distributed pathology, whereas borderline tuberculoid cases had an u nevenly distributed pathology; (7) the massive nerve regeneration obse rved was functionally ineffective-these findings indicate that the tot al nerve damage may affect the more peripheral nerve branches.