Publication: Botulinum toksininin kas hacmi üzerine etkisi: Deneysel çalışma / The effect of botulinum toxin on muscle volume: An experimental study
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Date
2018
Authors
Authors
GÜLEŞ, Mustafa Ekrem
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Volume Title
Publisher
Bezmialem Vakıf University
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Abstract
Botulinum Toxin A (BTx-A) has been used in clinical cosmetic practise worldwide, especially for improving facial rhytids. Earlier studies demonstrated that the repeated doses of BTx-A cause muscle atrophy. The development of muscle atrophy following chronic exposure serves to treat masseter hypertrophy. Reduction in masseter size is apparent only after continued inhibition of muscular contraction The injected muscle displays a reduction in volume temporarily. Despite its widespread use, there is no volumetric (quantitative) study focusing on the muscle volume alterations following the repeated injections of BTx-A with gradually increased doses. The gastrocnemius muscle has been found to be an ideal site for assesing the BTx-A effects on rats. We evaluated the effects of BTx-A injection in the right posterior gastrocnemius muscle of rats and aimed to determine the volume alterations in gastrocnemius muscle after repeated and gradually increased BTx-A injections followed by MRI assessment. Forty-eight male Sprague–Dawley rats with ranging weights of 300 to 350 grams have been used for the study. The rats were divided into 8 experimental groups. For 6 animals per group, the alterations in gastrocnemius volume were evaluated at regular intervals before and after the BTx-A injections using MRI. A vertical insicion was made in the right posterior leg of all rats for access to the gastrocnemius muscle. Groups 1 and 5 were injected sterile saline while the other groups were injected BTx-A into the muscular plane. The muscle volumes have been evaluated by MRI scanning for 5 times; on day 0 before the injection, on day 36 when the BTx-A has the maximum affect, on day 60 when the effect ends, on day 96 when the second injection has the maximum effect (on those injected) and on day 120 when the duration response of the second BTx-A injection ends. The 2nd, 3rd and 4th groups had statistically significant mean volume loss rates on day 36 compared to the day 0 values. When comparing the mean alterations of muscle volume preoperatively and on day 120 postoperatively, there was no statistically significant loss of muscle volume of the 2nd group, while groups 3 and 4 demonstrated statistically significant loss in gastrocnemius muscle volume on day 120. The percent amount of muscle volume changes were evaluated in groups 6,7 and 8 before (Day 0) and 36 days after the first injection. The percent amount of volume decrease was highest in group 8 and lowest in group 6, which demonstrated a similar pattern to the groups 2,3 and 4. The decrease in the percent amount of muscle volume was compared among groups 6 and 8 which demonstrated a statistically significant effect of the dose. We administrated the second injection 60 days after the first injection and assessed the percent amount of muscle volume change on the 96th day; the reductions were significantly more substantial in groups 6,7 and 8 than saline controls. The associated reductions in percent amount of muscle volume were significantly more substantial when BTx-A was administrated at higher doses. The reduction rate in percent amount of muscle was higher in group 8 compared to group 7, and also higher in group 7 compared to group 6. Comparing group 7 to group 8 and group 6 to group 8 respectively demonstrated an incremental decrease in percent amount of muscle at higher doses of injection which was statistically significant.
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Description
Thesis (Medical)--Bezmialem Vakıf University, Faculty of Medicine, Department of Plastic Reconstructive and Aesthetic Surgery, Istanbul, 2018
Keywords
Plastik ve Rekonstrüktif Cerrahi = Plastic and Reconstructive Surgery, Botulinum toksinleri = Botulinum toxins, Cerrahi-plastik = Surgery-plastic, Estetik = Aesthetics, Hipertrofi = Hypertrophy, Kas tonüsü = Muscle tonus, Kaslar = Muscles, Manyetik rezonans görüntüleme = Magnetic resonance imaging, Masseter kası = Maseter muscle, Sıçanlar = Rats