Histologic features of human orbicularis oculi treated with botulinum A toxin
C. P. Harris, K. Alderson, J. Nebeker, J. B. Holds and R. L. Anderson
Department of Neurology, University of Utah School of Medicine, Salt Lake City.
To evaluate muscle histologic features in humans following therapeutic
botulinum toxin injections, we studied orbicularis oculi from 11 patients
with blepharospasm; nine had previously received botulinum toxin injections
and two had not. All muscles had comparable variability in muscle fiber
diameter, with no necrosis, inflammation, denervation, or consistent
alterations in muscle fiber internal architecture. Botulinum toxin produces
no persistent histologic changes in human muscle fibers.
