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ID naloge: 30 Letnik: 1998 Predmet: patofiziologija
Obnova občutljivosti v področju prerezanega živca, od strani prišitega na nepoškodovan živec
Avtor: Uroš Kovačič
Mentor: prof. dr. Dušan Sket
Somentor: asist. mag. Fajko Bajrović, dr. med
Izhodišče. Če po poškodbi perifernega živca njegovega proksimalnega krna ni na voljo, potem je prišitje njegovega distalnega krna na nepoškodovani sosednji živec edina možnost za morebitno obnovo njegove funkcije. Znana je samo ena študija, v kateri so proučevali obnovo senzorične funkcije po anastomozi end to side in pri tem uporabili model s prekinjenim donorskim živcem distalno od anastomoze. Obnove senzorične funkcije po anastomozi end to side, pri kateri donorski živec ni bil poškodovan, še niso raziskovali.
Namen. Preverili bomo hipotezo, da je obnova senzorične funkcije poškodovanega perifernega živca prek anastomoze end to side z nepoškodovanim živcem mogoča.
Metode. V raziskavi smo pri podganah na nepoškodovani suralni živec od strani z epinevrijskimi šivi prišili prerezani distalni krn peronealnega živca. Vraščanje senzoričnih aksonov v distalne krne živcev, od strani prišitih na suralni živec, smo ugotavljali s testom vščipa živca in s štetjem mieliniziranih aksonov na prečnih rezih od strani prišitega peronealnega živca, ki smo jih obarvali z barvilom Azur II. Mielinizirana vlakna smo šteli in določali površino njihovih presekov tudi v suralnem živcu tako poskusnih kot tudi kontrolnih neoperiranih živali. Obnovo občutljivosti za bolečino na koži narta smo ugotavljali s testom vščipa kože.
Rezultati. V obdobju 18 tednov po prišitju prerezanega peronealnega živca od strani na nepoškodovan suralni živec so aksoni iz tega živca pri enajstih poskusnih živalih vedno brsteli v prišiti peronealni živec, ki je bil občutljiv na vščip, kolikor daleč je bilo mogoče testirati, in v katerem smo našli 277 ± 119 (srednja vrednost ± SD) mieliniziranih aksonov, katerih prečni presek je bil večinoma manjši od 10 µm2. Po osemnajstih tednih po anastomozi smo po prekinitvi suralnega živca dokazali delno obnovo občutljivosti za bolečino (19% do 40% površine kože v inervacijskem področju peronealnega živca) na nartu stopala pri treh od enajstih živali. Pri ostalih živalih se bolečinska občutljivost ni povrnila.
Sklep. Obnova občutljivosti na koži v področju prerezanega živca, ki je bil od strani prišit na nepoškodovani živec, je v načelu možna, vendar obstajajo še neznani dejavniki, ki jo lahko zakasnijo ali preprečijo
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[Abstract / English version]
Recovery of cutaneus pain sensitivity after end-to-side anastomosis of a transected peripheral nerve in the rat
Author: Uroš Kovačič
Mentor: prof. dr. Dušan Sket
Co-mentor: asist. mag. Fajko Bajrović, dr. med
Background. If the proximal nerve stump is not available after a peripheral nerve injury, end to side anastomosis of its distal stump remains the only possibility for some recovery of the injured nerve's function. Recovery of sensory function after end to side anastomosis has been examined in only one study in which the donor nerve was transected distally to the anastomosis. No study using uninjured donor nerve has been performed yet in this respect.
Objective. The hypothesis that recovery of sensory function of a transected nerve by using end to side anastomosis to an uninjured nerve is possible was examined.
Methods. Distal stump of a transected peroneal nerve was sutured end to side by epineurial sutures to intact sural nerve. Sprouting of sensory axons into anastomosed peroneal nerve was monitored by the nerve pinch test and the number of myelinated axons was counted on tissue cross-section stained by Azur II. Myelinated axons were counted and their cross-section areas were determined also in sural nerves of both control and operated animals. Pain sensitivity in the skin of the instep of the foot was examined by the skin pinch test.
Results. During 18 weeks after end to side anastomosis of the transected peroneal nerve to the intact sural nerve, the axons sprouted into the peroneal nerve in all 11 operated animals. The pinch test in the anastomosed distal stump of the peroneal nerve was positive in all animals as far as it was possible to test. There was 277 ± 119 myelinated axons in the anastomosed peroneal nerve, their cross area was mostly smaller than 10 µm2. The sural nerve was transected after 18 weeks and partial sensitivity of the instep skin (19-40% of the area of the innervation field of the peroneal nerve) was documented in three out of eleven animals. There was no pain sensitivity of this region in the rest of these animals.
Conclusion. Recovery of sensory function of a transected peripheral nerve, sutured end to side to an uninjured peripheral nerve is possible in principle. However, some poorly defined factors, can delay or prevent functional recovery under these conditions.
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