The purpose of the present study was to observe the morphological changes of nerve following intramuscular injection of Botulinum toxin A (B.toxin A) alone or combined with verapaunil or Lidocaine at the neuromuscular junction.
Thirty five rabbits were divided into five experimental groups : A saline, B; B.toxin A (2. 5U), Q B, toxin A (2.5U) with Lidocaine, D; B.toxin A (2.5U) with verapamil and E; B.toxin A (1.25U).
Degree of ptosis was measured daily, and morphological change of superior rectos muscle was examined on 3 days, 1 week, 2 weeks, 3 weeks, 4 weeks, 6 weeks and 8 weeks after injection. _:Light and electron microscopic observation was performed following H & E, Bodian silver stain. was performed following H & E and Bodian silver stain.
1. Degree of ptosis was most severe in B.toxin A (2.5U) group followed by combined verapamil or Lidocaine injected group (p<0.01).
The degree- of ptosis was more marked in the 2.5U group of B.toxin A than the 1.25U group.
2. Structural changes of the nerve included hydropic degeneration of axoplasm in both myelinated and unmyelinated nerve fibers as well as Schwann cells after 3days. Hydropic de-generation of axoplasm, death of Schwann cells and splitting of myelin sheath were marked after 3weeks.
3. The degree of the degenerative changes were most extensive in -B. toxin A (2.5U) group followed by combined verapamil or- lidocaine injected group. The reparative process and early sprouting of the nerve was noted after 6weeks in B. toxin A group and almost complete re-generation was noted after 8weeks in all groups.
4. The degree of morphologic changes was more marked in the 2.5U group of B. toxin A than 1, 25U group.
5. Muscular changes exhibited diffuse intracellular edema, atrophy, seperating myofilamernts ´
ciated with focal lysis and vacuolization.
Y It was suggested that the effeots of Botulinum toxin A couid be modified by combined apl,j1
tion of other drugs and different dosages of the B. toxin A in the clinical use.
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