Preventive effect of botulinum toxin A in microanastomotic thrombosis: A rabbit model

Intramuscular Neural Arborization of the Latissimus Dorsi Muscle: Application of Botulinum Neurotoxin Injection in Flap Reconstruction

Postoperative pain after breast reconstruction surgery with the latissimus dorsi flap is a common occurrence. Botulinum neurotoxin (BoNT) injection during surgery is effective in reducing postoperative pain. This study aimed to determine the most appropriate locations for BoNT injection. A modified Sihler’s method was performed on the latissimus dorsi muscles in 16 specimens. Intramuscular nerve arborization was noted under the landmark of the medial side surgical neck of the humerus to the line crossing the spinous process of T5 and the middle of the iliac crest. The latissimus dorsi muscles were divided into medial, middle, and lateral segments with 10 transverse divisions to give 10 sections (each 10%). Intramuscular nerve arborization of the latissimus dorsi muscle was the largest from the medial and lateral part of the muscle ranging from 40 to 60%, middle part from 30 to 60% and medial, middle and lateral part from 70 to 90%. The nerve entry points were at the medial and lateral part with 20–40% regarding the medial side of surgical neck of the humerus to the line crossing spinous process of T5 to the middle of iliac crest. These outcomes propose that an injection of BoNT into the latissimus dorsi muscles should be administered into specific zones.

The Use of Botulinum Toxin to Prevent Anastomotic Thrombosis and Promote Flap Survival: A Bridge to Developing Clinical Studies

BACKGROUND

Despite the possibility of using botulinum toxin to improve perfusion and prevent vasospasm, only a few studies have examined the use of botulinum toxin in the setting of flap surgery and thrombosis, and the mechanisms have not been fully explained.

OBJECTIVE

The primary objective of this study was to provide a comprehensive review of the effectiveness of botulinum toxin in anastomotic thrombosis prevention and surgical flap survival to determine the value of conducting large-scale human trials.

METHODS

Using the SYRCLE and CAMRADES criteria, a systematic review was performed. PubMed, Medline, EmBase, and the Cochrane Library were searched for studies that met our eligibility criteria.

RESULTS

Twenty studies were included in the final selection. A total of 397 subjects were included. Eighteen studies used botulinum toxin type A alone, one used botulinum toxin type B alone, and only one used both botulinum toxin type A and botulinum toxin type B. The most commonly used injection technique was a preoperative intradermal injection. The most common procedure performed was a pedicled flap with random pattern skin flaps (65%). The mean injection dose was 28.17 ± 49.21 IU, whereas the mean reported injection time for studies using animal models was 7.4 ± 6.84 days.

CONCLUSIONS

Similar mechanisms demonstrated in animal models may be replicable in humans, allowing botulinum toxin to be used to prolong flap survival. However, many factors, such as optimal injection techniques, dosages, and long-term outcomes of botulinum use in flap surgery, need to be further assessed before applying this to clinical practice.

Upper Extremity Deep Vein Thrombosis After Botulinum Toxin Injection: A Case Report

Botulinum toxin (BoNT) injection is widely used to improve spasticity. However, after the treatment, the patient may experience pain, inflammation, swelling and redness at the injection site. In this case, we addressed deep vein thrombosis (DVT) after BoNT treatment of the upper limb. A male aged 37 years had spasticity and dystonia in his left upper extremity. BoNT-A 100 U was injected into the left biceps brachii and an equal amount into the brachialis to relieve spasticity. After three days, he developed redness and painful swelling in the left upper arm and the next day, through the upper extremity computed tomography venography, DVT was identified in the left cephalic vein. The thrombus resolved after the anticoagulation therapy with rivaroxaban (Xarelto). We hypothesized the role of mainly three mechanisms in the development of DVT in this case: repetitive strenuous activity, relative stasis due to reduced muscle tone, and possible direct mechanical damage to the vessel wall.

Application of Botulinum Neurotoxin Injections in TRAM Flap for Breast Reconstruction: Intramuscular Neural Arborization of the Rectus Abdominis Muscle

Breast reconstruction after mastectomy is commonly performed using transverse rectus abdominis myocutaneous (TRAM) flap. Previous studies have demonstrated that botulinum neurotoxin injections in TRAM flap surgeries lower the risk of necrosis and allow further expansion of arterial cross-sectional diameters. The study was designed to determine the ideal injection points for botulinum neurotoxin injection by exploring the arborization patterns of the intramuscular nerves of the rectus abdominis muscle. A modified Sihler's method was performed on 16 rectus abdominis muscle specimens. Arborization of the intramuscular nerves was determined based on the most prominent point of the xyphoid process to the pubic crest. All 16 rectus abdominis muscle specimens were divided into four muscle bellies by the tendinous portion. The arborized portions of the muscles were located on the 5-15%, 25-35%, 45-55%, and 70-80% sections of the 1st, 2nd, 3rd, and 4th muscle bellies, respectively. The tendinous portion was located at the 15-20%, 35-40%, 55-60%, and 90-100% sections. These results suggest that botulinum neurotoxin injections into the rectus abdominis muscles should be performed in specific sections.

Effect of Ethanol on Micro-Vessels Diameter and Prevention of Thrombosis

BACKGROUND

Microvascular surgery is one of the most important parts of reconstructive surgery. In the present study, the effect of ethanol on microvascular diameter and prevention of thrombosis was evaluated.

METHODS

Totally, 80 vessels including 40 arteries and 40 veins in right and left ears of 20 adult rabbits were enrolled. Seven days after injection of ethanol to rabbit ear vessel, vessel diameter and thrombosis rate post-iced saline challenge were documented and compared to normal saline injection in contralateral ear as a control group.

RESULTS

Vessel diameter in both arteries and veins in ethanol group was significantly larger than normal saline control group, and patency rates due to preventive effect of ethanol were also significantly higher in the ethanol group after iced saline challenge.

CONCLUSION

Pretreatment with ethanol can enlarge vessel diameter and play a preventive role on thrombosis after iced saline challenge.

Botulinum Toxin Type A Attenuates Apoptosis in Human Dermal Microvascular Endothelial Cells Exposed to an In Vitro Model of Ischemia/Reperfusion Injury

BACKGROUND

Botulinum toxin type A (BTXA) has been reported to increase survival of critically ischemic skin flaps; however, the effect of BTXA in human dermal microvascular endothelial cells (HDMECs) remains to be investigated. This study aimed to investigate the protective effect of BTXA in HDMECs exposed to an in vitro model of ischemia/reperfusion injury.

METHODS

HDMECs were isolated from human upper eyelid tissue and were randomly divided into 3 groups: 1.

CONTROL GROUP

culture under normoxic conditions (95% air and 5% CO₂); 2. hypoxia/reoxygenation (H/R) group: culture in a hypoxic incubator (94% N₂ + 5% CO₂ + 5% O₂) for 8 hours, followed by culture in saturated aerobic culture medium for 24 hours; and 3. BTXA group: treatment with BTXA for 12 hours before exposure to hypoxic conditions. Flow cytometry was used to analyze the apoptosis of HDMECs, and western blotting was used to detect the expression of apoptosis-related proteins.

RESULTS

H/R leads to severe injury in HDMECs, as evidenced by an increase in the percentage of apoptosis and an increase in expression of apoptosis-related proteins (Bax, cleaved-caspase-3, and cytochrome C). Moreover, H/R results in a decrease in expression of anti-apoptotic protein (Bcl-2), which can be significantly attenuated with BTXA treatment.

CONCLUSION

BTXA protects against apoptosis in HDMECs exposed to an in vitro model of H/R-induced injury.

Effect of Perivascular Injection of Botulinum Toxin Type A versus Lidocaine in Survival of Random Pattern Flaps in a Rat Model

BACKGROUND

Botulinum toxin type A has gained popularity in many clinical fields, for a variety of aesthetic and therapeutic purposes. In addition, there have been reports regarding the positive effect of botulinum toxin type A on flap survival by various mechanisms. This study examines the role of botulinum toxin type A and lidocaine in augmentation of flap survival and decreasing the rate of necrosis in random pattern cutaneous flaps.

METHODS

In 45 male Sprague-Dawley rats, random pattern skin flaps with different width-to-length ratios were elevated. Botulinum toxin type A, lidocaine, or saline was administered to the base and whole length of the flap. Flap survival was evaluated on day 10 after surgery. The area of flap survival was determined grossly on the basis of its appearance, color, and texture.

RESULTS

The botulinum toxin type A group had a greater survival area (p < 0.05) compared with the lidocaine or saline group in flaps with width-to-length ratios of 1:2 and 1:3; however, compared with a width-to-length ratio of 1:1, the flap survival rate shows no statistically significant variations.

CONCLUSION

Injection of botulinum toxin type A in random pattern skin flaps improves tissue perfusion and increases the rate of flap survival more than lidocaine in flaps with width-to-length ratios of 1:2 and 1:3.

The Use of Botulinum Toxin in Flap Surgery: A Review of the Literature

Botulinum neurotoxin-A and botulinum neurotoxin-B have been shown to play a potential role in improving flap survival in animal models. The aim of this study is to review indications as well as to study injection timing, technique, and doses of botulinum neurotoxin-A and botulinum neurotoxin-B in animal models. Seventeen articles describe a total of 266 animals that underwent botulinum toxin injections before or during flap harvesting or vascular anastomosis procedure. All the studies demonstrated a beneficial effect of botulinum toxin administration in flap surgery or vascular anastomosis. Botulinum neurotoxin-A injection was shown to be a reliable approach in reducing vascular complications rate and increasing survival of flaps in animal models. The main conclusions drawn from the study include the following: perivascular injections targeting each vascular pedicle are preferred in cases of free flaps or axial flaps; subdermal injections are favorable in cases of random pattern skin flaps; and injections should be performed 7 days before flap elevation.

Role of botulinum neurotoxin-A in cerebral revascularization graft vasospasm prevention: current state of knowledge

Graft stenosis and occlusion remain formidable complications in cerebral revascularization procedures, which can lead to significant morbidity and mortality. Graft vasospasm can result in early postoperative graft stenosis and occlusion and is believed to be at least partially mediated through adrenergic pathways. Despite various published treatment protocols, there is no single effective spasmolytic agent. Multiple factors, including anatomical and physiological variability in revascularization conduits, patient age, and comorbidities, have been associated with graft vasospasm pathogenesis and response to spasmolytics. The ideal spasmolytic agent thus likely needs to target multiple pathways to exert a generalizable therapeutic effect. Botulinum toxin (BTX)-A is a powerful neurotoxin widely used in clinical practice for the treatment of a variety of spastic conditions. Although its commonly described paradigm of cholinergic neural transmission blockade has been widely accepted, evidence for other mechanisms of action including inhibition of adrenergic transmission have been described in animal studies. Recently, the first pilot study demonstrating clinical use of BTX-A for cerebral revascularization graft spasm prevention has been reported. In this review, the mechanistic basis and potential future clinical role of BTX-A in graft vasospasm prevention is discussed.

Relaxation matters: comparison of in-vitro vasodilatory role of botulinum toxin-A and papaverine in human radial artery grafts

Background

Radial artery (RA) is widely used in coronary artery bypass (CABG) surgery and the prevention of spasm is crucial for graft patency. Botulinum toxin A (BTX-A) and B are commonly used for aesthetic reasons and neuromuscular disorders. They are proven to raise blood flow and increase survival of ischemic skin flaps. In this study we evaluated and compared the vasodilator effects of BTX-A and papaverine on human RA grafts.

Methods

After resting 60 min in isolated organ baths, human RA grafts were examined. Contraction responses for different doses of serotonin (5-HT) and endothelin-1 (ET-1) were evaluated as a percent of maximum contraction response elicited by 80 mM potassium chloride (KCl). The inhibitory effects of BTX-A and papaverine on contraction responses taken at the 0th hour were compared with the 1st and 2nd hour responses. Inhibitory effects of BTX-A and papaverine against the contractile agent were evaluated by comparing the results of the first and last (0th and 2nd hour) application.

Results

In low concentrations, when we compared the effects of BTX-A (10^− 8 M) and papaverine (10^− 6 M) on 5-HT, papaverine was found to be more effective at both the 0th and 2nd hour (p < 0.05). Both BTX-A and papaverine inhibited the maximum contractile effect of ET-1 to the same extent at the 0th hour; but, the inhibitory effect of BTX-A was significantly stronger at the 2nd hour (p < 0.05).

In high concentrations, when we compared the effects of BTX-A (10^− 6 M) and papaverine (10^− 4 M) on 5-HT, papaverine showed stronger inhibition (p < 0.05), whereas both agents had similar action of inhibition on ET-1 mediated maximum contraction responses.

Conclusion

BTX-A inhibits both ET-1 and 5-HT induced contractions and its effectiveness does not decrease over time as observed with papaverine. This study is the first in the literature using human RA for prevention of vasospasm by BTX-A.

Botulinum toxin B suppresses the pressure ulcer formation in cutaneous ischemia-reperfusion injury mouse model: Possible regulation of oxidative and endoplasmic reticulum stress

BACKGROUND

We previously identified that botulinum toxin A (BTX-A) suppressed pressure ulcer (PU) formation after cutaneous ischemia-reperfusion (I/R) injury; however, regulation of cutaneous I/R-induced oxidative and endoplasmic reticulum (ER) stress by BTX-B was not investigated. Additionally, the efficacy of BTX-B injection has never been examined.

OBJECTIVE

Objective was to assess the effects of BTX-B on the formation of PU by cutaneous I/R injury, and the regulation of oxidative and ER stress in I/R injury by BTX-B.

METHODS

BTX-B was subcutaneously injected into I/R area, and wound size, vascular damage, hypoxic area, and apoptotic cells in I/R area were analyzed. We evaluated the extent of oxidative and ER stress in I/R area by using OKD48 mice and ERAI mice, respectively, which enabled evaluating oxidative and ER stress through bioluminescence detection.

RESULTS

BTX-B injection significantly suppressed the formation of PU by cutaneous I/R injury. Cutaneous I/R-induced vascular damage, hypoxic area, and number of oxidative-damaged cells and apoptotic cells were suppressed by BTX-B injection. BTX-B administration significantly inhibited I/R-induced oxidative stress signal in OKD48 mice. BTX-B reduced the I/R-induced oxidative stress-associated factors. BTX-B significantly inhibited the oxidant-induced reactive oxygen species and apoptosis of endothelial cells and fibroblasts. BTX-B significantly inhibited I/R-induced ER stress signal in ERAI mice. Cutaneous I/R injury-induced ER stress-response factors and GRP78/BiP and CHOP-positive cells in I/R area were significantly decreased by BTX-B injection.

CONCLUSION

BTX-B injection might have protective effects against PU formation after cutaneous I/R injury by reducing vascular damage, hypoxia-induced oxidative and ER stress, and apoptosis.

Botulinum Toxin A Upregulates Rac1, Cdc42, and RhoA Gene Expression in a Dose-Dependent Manner: In Vivo and in Vitro Study

Angiogenesis is the development of new capillaries from existing blood vessels and is a prerequisite for the wound-healing process. Many lines of scientific evidences have shown that complicated roles of small guanosine triphosphatases (GTPases) (ras-related C3 botulinum toxin substrate 1 [Rac1], cell division control protein 42 [Cdc42], and ras homolog gene family, member A [RhoA]) in regulation of signal transduction pathways exist to transmit distinct cellular effects on the modulation of actin cytoskeleton remodeling such as cell cycle progression, cell survival, and cell motility. In addition, these small GTPases activate mitogen-activated protein kinase kinase kinases (MAP3Ks) leading to activated mitogen-activated protein kinase kinases (MAPKK), mitogen-activated protein kinase (MAPK), and various transcription factors such as vascular endothelial growth factor with involvement of MAPK signaling pathways.In this study, the authors hypothesized that botulinum toxin A increases angiogenesis via the expression of small GTPases in vivo and in vitro studies.In vivo experiment, 24 Sprague-Dawley rats were randomly divided into 2 groups: a control group and a botulinum toxin A group. Five days prior to superiorly based transverse rectus abdominis myocutaneous flap elevation, the botulinum toxin A (BoTA) group was pretreated with BoTA, while the control group was pretreated with normal saline. quantitative real-time polymerase chain reaction was performed to evaluate the expression of Rac1, RhoA, and Cdc42.The angiogenic effects of botulinum toxin A on human dermal fibroblasts were measured in vitro experiment. To understand the mechanism of botulinum toxin A on small GTPases production of fibroblasts, Rac1, Cdc42, and RhoA were measured using qRT-PCR.The relative messenger ribonucleic acid expression of Rac1, RhoA, and Cdc42 was significantly higher in the BoTA group than in the control group, in every zone and pedicle muscle, on postoperative days 1, 3, and 5. Levels of these molecules increased significantly in human dermal fibroblasts grown in the presence of BoTA compared with control group over 5 IU.Our in vivo and in vitro studies suggest that administration of BoTA upregulates the expression of RhoA, Rac1, and Cdc42 in a dose-dependent manner. MAPK signaling pathway might be involved in BoTA-induced angiogenesis mechanism.

LEVEL OF EVIDENCE

N/A.

Prevention of unfavourable effects of cigarette smoke on flap viability using botulinum toxin in random pattern flaps: An experimental study

BACKGROUND

There are numerous clinical and experimental studies reporting unfavourable effects of cigarette smoke on skin flaps.

OBJECTIVE

To investigate whether unfavourable effects of cigarette smoke on flap survival could be reduced by botulinum toxin type A.

METHODS

Twenty-eight male Wistar albino rats (15 months of age, mean weight 210 g [range 180 g to 230 g]) were included. They were divided into four groups of seven animals each. The control group underwent the surgical procedure alone. Surgical procedure was performed after administration of botulinum toxin type A in the botulinum toxin (BTX) group, after exposure to cigarette smoke in the cigarette smoke (CS) group, and after BTX type A administration and exposure to CS in the CS+BTX (CS+BTX) group. Random pattern cutaneous flaps (3 cm × 9 cm) were elevated from the dorsum of all rats. Necrosis area was calculated in percentages (%) using Image J computer software. Tissue samples were examined histopathologically.

RESULTS

The mean necrotic area in the control group (26%) and in the BTX group (21%) were similar (P=0.497), whereas administration of BTX type A significantly decreased flap necrosis area in the rats exposed to CS (the mean necrosis areas were 41.5% in the CS group, and 26% in the CS+BTX group; P<0.001). Histopathological examination findings corroborated the unfavourable effects of CS and preventive effects of BTX type A.

CONCLUSION

Preoperative administration of BTX significantly enhanced flap viability in the rats exposed to CS. Further human studies are warranted to verify whether BTX type A could be used as an agent to reduce the risk of flap necrosis in patients who smoke.

Prevention of unfavourable effects of cigarette smoke on flap viability using botulinum toxin in random pattern flaps: An experimental study

Background

There are numerous clinical and experimental studies reporting unfavourable effects of cigarette smoke on skin flaps.

Objective

To investigate whether unfavourable effects of cigarette smoke on flap survival could be reduced by botulinum toxin type A.

Methods

Twenty-eight male Wistar albino rats (15 months of age, mean weight 210 g [range 180 g to 230 g]) were included. They were divided into four groups of seven animals each. The control group underwent the surgical procedure alone. Surgical procedure was performed after administration of botulinum toxin type A in the botulinum toxin (BTX) group, after exposure to cigarette smoke in the cigarette smoke (CS) group, and after BTX type A administration and exposure to CS in the CS+BTX (CS+BTX) group. Random pattern cutaneous flaps (3 cm × 9 cm) were elevated from the dorsum of all rats. Necrosis area was calculated in percentages (%) using Image J computer software. Tissue samples were examined histopathologically.

Results

The mean necrotic area in the control group (26%) and in the BTX group (21%) were similar (P=0.497), whereas administration of BTX type A significantly decreased flap necrosis area in the rats exposed to CS (the mean necrosis areas were 41.5% in the CS group, and 26% in the CS+BTX group; P<0.001). Histopathological examination findings corroborated the unfavourable effects of CS and preventive effects of BTX type A.

Conclusion

Preoperative administration of BTX significantly enhanced flap viability in the rats exposed to CS. Further human studies are warranted to verify whether BTX type A could be used as an agent to reduce the risk of flap necrosis in patients who smoke.

Protective effect of botulinum toxin A after cutaneous ischemia-reperfusion injury

Botulinum toxin A (BTX-A) blocks the release of acetylcholine vesicles into the synaptic space, and has been clinically used for aesthetic indications, neuromuscular disorders and hyperhidrosis. Several studies have demonstrated that BTX-A enhanced the blood flow and improved ischemia in animal models. Our objective was to assess the effects of BTX-A on cutaneous ischemia-reperfusion (I/R) injuries, mimicking decubitus ulcers. The administration of BTX-A in I/R areas significantly inhibited the formation of decubitus-like ulcer in cutaneous I/R injury mouse model. The number of CD31(+) vessels and αSMA(+) pericytes or myofibroblasts in wounds were significantly increased in the I/R mice treated with BTX-A. The hypoxic area and the number of oxidative stress-associated DNA-damaged cells and apoptotic cells in the I/R sites were reduced by BTX-A administration. In an in vitro assay, BTX-A significantly prevented the oxidant-induced intracellular accumulation of reactive oxygen species (ROS) in vascular endothelial cells. Furthermore, the administration of BTX-A completely suppressed the ulcer formation in an intermittent short-time cutaneous I/R injury model. These results suggest that BTX-A might have protective effects against ulcer formation after cutaneous I/R injury by enhancing angiogenesis and inhibiting hypoxia-induced cellular damage. Exogenous application of BTX-A might have therapeutic potential for cutaneous I/R injuries.

The role of botulinum toxin in vasospastic disorders of the hand

Raynaud phenomenon may be a primary disorder or associated with a variety of other autoimmune processes. Raynaud phenomenon produces digital vasospasm, which can lead to ischemia and ulceration. The treatment of Raynaud phenomenon has been difficult because multiple medical treatments have not provided uniform resolution of symptoms. Many patients have turned to surgery and sympathectomies for the treatment of unrelenting vasospasm. Botulinum toxin has been shown to be an effective alternative to surgery, with a single treatment being capable of resolving pain and healing ulcer. This article reviews the use of botulinum toxin for the treatment of Raynaud phenomenon.

The effect of botulinum toxin B pretreatment to the blood flow in the microvascular anastomosis

BACKGROUND

Although multiple factors can lead to free flap failure, vessel-related accidents are the most important. Many methods have been developed (both intraoperative and postoperative) to prevent vessel-related complications. In this article, we study the effects of a "preoperative treatment" using botulinum toxin B that could enhance the velocity and blood flow of vascular pedicles and decrease vascular accidents.

METHODS

Ten Sprague-Dawley rats were pretreated with botulinum toxin type B at the perivascular area of the femoral vessel. Ten other rats were injected with saline as a control group. After 3 days, pedicle diameter and the peak mean frequency of blood in the pedicle were measured using laser Doppler flowmetry, and the peak mean blood velocity was calculated. We performed a "pedicle division and reanastomosis" operation to compare changes in vessel diameter and peak mean blood velocity.

RESULTS

Vessel diameter was significantly increased in the botox-pretreated group for both veins and arteries. A comparison of the deep femoral vein and artery blood velocities showed that the peak mean velocity was significantly higher in the botox group. The average increase in blood velocity was significantly larger in the botox group.

CONCLUSIONS

Botulinum toxin B is helpful by influencing the microvascular environment through an increase in the blood velocity of the pedicle.