Injection of high dose botulinum-toxin A leads to impaired skeletal muscle function and damage of the fibrilar and non-fibrilar structures

Anatomical etiology of bunny lines based on cadaveric dissection and ultrasonographic evaluation

Bunny lines are vertical and diagonal wrinkles attributed to contractions of the nasalis muscle. Common management involves botulinum toxin (BoNT) injections into wrinkles immediately below the nasal bridge. Here, we investigated the anatomical structures underneath bunny lines and their relationships with adjacent muscular structures. The area between the medial canthus and nasal dorsum was examined by ultrasonography in 13 adult volunteers (mean age, 29.4 years) and dissected in 39 cadavers. The findings consistently showed a non-muscular area (bunny triangle) between the borders of the procerus, nasalis, orbicularis oculi (OOc), and levator labii superioris alaeque nasi (LLSAN) muscles. The size and shape of the bunny triangle vary according to the width of the procerus and nasalis muscles. The muscles neighboring the bunny lines affect the thinning of the thin skin between the medial canthus and nasal dorsum. Our results indicate that conventional BoNT injection into bunny line wrinkles is likely to target connective tissue rather than a muscle, potentially producing suboptimal results. Therefore, the BoNT injection points probably need to target the borders of the procerus, nasalis, OOc, and LLSAN muscles to be most efficient.

Intramuscular neural distribution of the vastus medialis for botulinum neurotoxin injection: application to spasticity

PURPOSE

A comprehensive understanding of neural distribution within the vastus medialis is crucial for the effective administration of botulinum neurotoxin injections to manage spasticity. The aim of this study was to develop an anatomically informed approach to guide the administration of botulinum neurotoxin injections into the vastus medialis muscle.

METHODS

Using a modified Sihler's method, we examined the vastus medialis muscles (20 specimens) to delineate the distribution of nerves relative to a transverse line extending from the anterior superior iliac spine to the base of patella. The vastus medialis muscle was divided into 10 areas from top to bottom. Then, using two fresh cadavers, ultrasonography-guided injections were performed based on the distribution of nerves within the vastus medialis. Each specimen was subsequently dissected to verify if the dye was accurately directed to the most densely innervated regions of the vastus medialis and to assess the precision of the injections.

RESULTS

The intramuscular nerve distribution within the vastus medialis muscle showed distinct patterns, particularly in areas between 6 and 9. Four injections were successfully administered on each side, targeting the regions between 6 and 9 of the vastus medialis. Upon dissection of the cadavers, the dye was found to be distributed along the muscle fiber.

CONCLUSION

We recommend targeting botulinum neurotoxin injections toward regions displaying a prominent nerve distribution, specifically focusing on areas between 6 and 9. By adhering to these guidelines, clinicians can minimize doses and mitigate potential adverse effects, such as gait disturbances, antibody development, and bruising, resulting from multiple injections. Furthermore, these findings can be incorporated into electromyography practices.

An Ultrasonographic Analysis of the Deep Inferior Tendon in the Masseter Muscle: Implications for Botulinum Toxin Injections

(1) Background: With the increasing aesthetic pursuit of facial features, the clinical use of Botulinum Toxin Type A (BoNT-A) injections for masseter hypertrophy has been on the rise. However, due to variations in masseter muscle structure and differences in clinicians' injection techniques, blind injections may lack precision, potentially compromising treatment accuracy and increasing the risk of complications. (2) Objectives: The study aims to use ultrasonography to detail the deep inferior tendon (DIT) within the masseter muscle in a young Chinese cohort, refine its classification, analyze muscle belly thickness and variations across groups, and propose a customized ultrasound-guided BoNT-A injection protocol. (3) Methods: Ultrasound imaging was used to observe the bilateral masseter muscles at rest and during clenching. The features of the DIT were classified from these images, and the thickness of the masseter's distinct bellies associated with the DIT types was measured in both states. (4) Results: The study cohort included 103 participants (27 male, 76 female), with 30 muscles in the normal masseter group and 176 muscles in the hypertrophy group. The DIT was categorized as Type A, B (subtypes B1, B2), and C. The distribution of these types was consistent across normal, hypertrophic, and gender groups, all following the same trend (B > A > C). In hypertrophy, Type B1 showed uniform thickness across masseter bellies, B2 presented with a thinner intermediate belly, and Type C had mainly superficial muscle enlargement. Changes in muscle thickness during clenching were noted but not statistically significant among different bellies. (5) Conclusions: The study evidences individual variation in the DIT, highlighting the importance of precise DIT classification for effective BoNT-A injections. A tailored ultrasound-guided BoNT-A injection strategy based on this classification may enhance safety and efficacy of the therapy.

The Effect of Botulinum Neurotoxin-A (BoNT-A) on Muscle Strength in Adult-Onset Neurological Conditions with Focal Muscle Spasticity: A Systematic Review

Botulinum neurotoxin-A (BoNT-A) injections are effective for focal spasticity. However, the impact on muscle strength is not established. This study aimed to investigate the effect of BoNT-A injections on muscle strength in adult neurological conditions. Studies were included if they were Randomised Controlled Trials (RCTs), non-RCTs, or cohort studies (n ≥ 10) involving participants ≥18 years old receiving BoNT-A injection for spasticity in their upper and/or lower limbs. Eight databases (CINAHL, Cochrane, EMBASE, Google Scholar, Medline, PEDro, Pubmed, Web of Science) were searched in March 2024. The methodology followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and was registered in the Prospective Register of Systematic Reviews (PROSPERO: CRD42022315241). Quality was assessed using the modified Downs and Black checklist and the PEDro scale. Pre-/post-injection agonist, antagonist, and global strength outcomes at short-, medium-, and long-term time points were extracted for analysis. Following duplicate removal, 8536 studies were identified; 54 met the inclusion criteria (3176 participants) and were rated as fair-quality. Twenty studies were analysed as they reported muscle strength specific to the muscle injected. No change in agonist strength after BoNT-A injection was reported in 74% of the results. Most studies' outcomes were within six weeks post-injection, with few long-term results (i.e., >three months). Overall, the impact of BoNT-A on muscle strength remains inconclusive.

The impact of the migraine treatment onabotulinumtoxinA on inflammatory and pain responses: Insights from an animal model

OBJECTIVE

Migraine, a prevalent and debilitating disease, involves complex pathophysiology possibly including inflammation and heightened pain sensitivity. The current study utilized the complete Freund's adjuvant (CFA) model of inflammation, with onabotulinumtoxinA (BoNT/A) as a treatment of interest due to its use in clinical migraine management. Using an animal model, the study sought to investigate the role of BoNT/A in modulating CFA-induced inflammation, alterations in pain sensitivity, and the regulation of calcitonin gene-related peptide (CGRP) release. Further, we aimed to assess the changes in SNAP-25 through western blot analysis to gain insights into the mechanistic action of BoNT/A.

METHODS

BoNT/A or control was administered subcutaneously at the periorbital region of rats 3 days before the induction of inflammation using CFA. Periorbital mechanical sensitivity was assessed post-inflammation, and alterations in CGRP release were evaluated. Changes in SNAP-25 levels were determined using western blot analysis.

RESULTS

Upon CFA-induced inflammation, there was a marked increase in periorbital mechanical sensitivity, with the inflammation side showing increased sensitivity compared to other periorbital areas. BoNT/A did decrease the withdrawal thresholds in the electronic von Frey test. Despite not being able to observe differences in pain thresholds or CGRP release, BoNT/A reduced baseline release under CFA inflamed conditions. Analysis of SNAP-25 levels in the trigeminal ganglion revealed both intact and cleaved forms that were notably elevated in BoNT/A-treated animals. These findings, derived from western blot analysis, suggest an effect on neurotransmitter release.

CONCLUSION

Our investigation highlights the role of BoNT/A in reducing baseline CGRP in the context of inflammation and its involvement in SNAP-25 cleavage. In contrast, BoNT/A did not appear to alter facial pain sensitivity induced by inflammation, suggesting that mechanisms other than baseline CGRP could be implicated in the elevated thresholds in the CFA model.

Trends in prescription and cost of Sativex, a cannabinoid-based medicine, in treating patients with multiple sclerosis in England

Aim

Cannabis-based medication has recently been made available in the NHS for reducing pain and spasticity in patients with multiple sclerosis (MS). The currently available preparation of Sativex (nabiximols) contains a combination of botanical cannabis extracts with cannabidiol (CBD) and tetrahydrocannabinol (THC) with almost equal amounts in addition to minor cannabinoids and terpenoids and is delivered via an oro-mucosal spray. The present study aims to examine the use and trends in prescribing cannabinoid-based Sativex to control pain in patients diagnosed with MS.

Methods

Primary care prescribing data for cannabinoid-based Sativex (2013-2022) from the Prescription Cost Analysis were extracted and analysed. Linear regression analyses were performed to examine prescription trends and prescription costs (average change per year).

Results

There was a general increasing trend in the number of prescriptions each year, from 4.42 items dispensed per 100,000 people in 2013 to 5.15 in 2022. Overall, prescription items for cannabinoid-based Sativex increased by 0.34% per year (95% CI:-3.98, 4.67, p = 0.860) on average between 2013 and 2022. On average, a 2.43% (95% CI: -5.78, 0.92, p = 0.133) increase per year was observed for the costs of cannabinoid-based Sativex from 2013 to 2022.

Conclusion

The results suggested that cannabinoid-based Sativex should be considered an option due to its effectiveness, acceptable tolerance, and safety profile in the prescribing of Sativex.

Do repetitive botulinum neurotoxin injections induce muscle fibrosis? Sonographic observation of the masseter muscle

OBJECTIVE

In the esthetic field, the masseter muscle is commonly targeted by botulinum neurotoxin for facial contouring. However, multiple botulinum neurotoxin injections have been reported to cause muscle fibrosis. Ultrasonography can be useful for clinical consideration in such cases.

MATERIALS AND METHODS

This study presents nine cases of masseteric fibrosis caused by repeated botulinum neurotoxin injections with ultrasonographic analysis of full and partial masseteric fibrosis.

RESULTS

Repetitive botulinum neurotoxin injections resulted in reduced masseter muscle volume, which frequently appeared hyperechoic on ultrasonography. The hyperechoic region was mostly located in the deep and posterior portions; however, in some cases, it was observed throughout the muscle, including the superficial, deep, or both areas.

CONCLUSION

The fibrotic masseter muscles appear hyperechoic, and ultrasonography is necessary to analyze the degree and location of fibrosis. Predictions can be made for cases in which botulinum neurotoxin injections may have less of an effect after ultrasonography. Because muscle fibrosis can be localized, it is necessary to confirm the degree and location of fibrosis before determining the effective area of injection. In clinical practice, muscle fibrosis may be visible in a specific area where blind injections are administered.

Short-Term Effects of Botulinum Toxin-A Injection on the Medial Gastrocnemius Histological Features in Ambulant Children with Cerebral Palsy: A Longitudinal Pilot Study

Botulinum toxin-A (BoNT-A) injection is known to exert beneficial effects on muscle tone, joint mobility and gait in children with cerebral palsy (CP). However, recent animal and human studies have raised the concern that BoNT-A might be harmful to muscle integrity. In CP-children, the impact of BoNT-A on muscle structure has been poorly studied, and inconsistent results have been reported. This study was aimed at determining the time course effect of a single BoNT-A administration on medial gastrocnemius (MG) morphology in CP-children. MG microbiopsies from 12 ambulant and BoNT-A-naïve CP-children (age, 3.4 (2.3) years, ranging from 2.5 to 7.8 years; seven boys and five girls; GMFCS I = 5, II = 4 and III = 3) were collected before and 3 and 6 months after BoNT-A treatment to analyze the fiber cross-sectional area (fCSA) and proportion; capillarization; and satellite cell (SC) content. Compared with the baseline, the fCSA decreased at 3 months (-14%, NS) and increased at 6 months (+13%, NS). Fiber size variability was significantly higher at 3 months (type I: +56%, p = 0.032; type IIa: +37%, p = 0.032) and 6 months (type I: +69%, p = 0.04; type IIa: +121%, p = 0.032) compared with the baseline. The higher type I proportion seen at 3 months was still present and more pronounced at 6 months (type I: +17%, p = 0.04; type IIx: -65%, p = 0.032). The capillary fiber density was reduced at 3 months (type I: -43%, NS; type II: -44%, p = 0.0320) but normalized at 6 months. There was a non-significant increase in SC/100 fibers at 3 months (+75%, NS) and 6 months (+40%, NS) compared with the baseline. These preliminary data suggest that BoNT-A induced alterations in the MG of children with CP, which were still present 6 months after BoNT-A injection but with signs of muscle recovery.

Comparison of the Effects of Botulinum Toxin Doses on Nerve Regeneration in Rats with Experimentally Induced Sciatic Nerve Injury

This study was designed to compare the effects of various doses of botulinum neurotoxin A (BoNT/A) on nerve regeneration. Sixty-five six-week-old rats with sciatic nerve injury were randomly allocated to three experimental groups, a control group, and a sham group. The experimental groups received a single session of intraneural BoNT/A (3.5, 7.0, or 14 U/kg) injection immediately after nerve-crushing injury. The control group received normal intraneural saline injections after sciatic nerve injury. At three, six, and nine weeks after nerve damage, immunofluorescence staining, an ELISA, and toluidine blue staining was used to evaluate the regenerated nerves. Serial sciatic functional index analyses and electrophysiological tests were performed every week for nine weeks. A higher expression of GFAP, S100β, GAP43, NF200, BDNF, and NGF was seen in the 3.5 U/kg and 7.0 U/kg BoNT/A groups. The average area and myelin thickness were significantly greater in the 3.5 U/kg and 7.0 U/kg BoNT/A groups. The sciatic functional index and compound muscle action potential amplitudes exhibited similar trends. These findings indicate that the 3.5 U/kg and 7.0 U/kg BoNT/A groups exhibited better nerve regeneration than the 14 U/kg BoNT/A and control group. As the 3.5 U/kg and the 7.0 U/kg BoNT/A groups exhibited no statistical difference, we recommend using 3.5 U/kg BoNT/A for its cost-effectiveness.

Novel anatomical guidelines for botulinum neurotoxin injection in the mentalis muscle: a review

The mentalis muscle is a paired muscle originating from the alveolar bone of the mandible. This muscle is the main target muscle for botulinum neurotoxin (BoNT) injection therapy, which aims to treat cobblestone chin caused by mentalis hyperactivity. However, a lack of knowledge on the anatomy of the mentalis muscle and the properties of BoNT can lead to side effects, such as mouth closure insufficiency and smile asymmetry due to ptosis of the lower lip after BoNT injection procedures. Therefore, we have reviewed the anatomical properties associated with BoNT injection into the mentalis muscle. An up-to-date understanding of the localization of the BoNT injection point according to mandibular anatomy leads to better injection localization into the mentalis muscle. Optimal injection sites have been provided for the mentalis muscle and a proper injection technique has been described. We have suggested optimal injection sites based on the external anatomical landmarks of the mandible. The aim of these guidelines is to maximize the effects of BoNT therapy by minimizing the deleterious effects, which can be very useful in clinical settings.

Rivastigmine ameliorates botulinum-induced hippocampal damage and spatial memory impairment in male rats

Botulinum toxin (Botox) is widely used in beauty industry and its long-term consequences can be a matter of concern. The hippocampal cholinergic system plays a significant role in memory and learning that could be affected by Botulinum toxin. However, to date, the effect of Botox on memory system has been controversial. This survey aimed to examine the effects of Botox on spatial memory, and biochemical and histological parameters of the hippocampus in male rats by using Rivastigmine (R) as a cholinesterase inhibitor that is more selective for the central nervous system (CNS). Thirty-five male Wistar rats (200-250 g) were distributed into seven groups: Sham, Botox A (3, 6, and 15 IU intramascularly) and Botox A (3, 6, and 15 IU) plus Rivastigmine (1 mg/kg intraperitoneally). Spatial memory was assessed in the Morris Water Maze (MWM) 4 weeks later. Moreover, the hippocampal tissue was removed for histopathological and biochemical analyses. Botox significantly impaired memory performance in MWM by increasing escape latency and swim distance and decreasing the time spent in the target zone. Furthermore, in the Botox groups, the level of acetylcholine decreased, while the level of the acetylcholinesterase enzyme increased significantly in the hippocampus. Also, local lesions were observed in the form of degeneration and loss of pyramidal neurons, as well as a decrease in the volume and shrinkage of the cell body and an increase in microglia in the damaged area. Rivastigmine administration alleviated biochemical and histological parameters and partially ameliorated Botox-induced impairments. In summary, rivastigmine could be a suitable protective approach for side effects of Botox in the hippocampus.

Botulinum Toxin Treatment of Adult Muscle Stem Cells from Children with Cerebral Palsy and hiPSC-Derived Neuromuscular Junctions

Botulinum neurotoxin type-A (BoNT) injections are commonly used as spasticity treatment in cerebral palsy (CP). Despite improved clinical outcomes, concerns regarding harmful effects on muscle morphology have been raised, and the BoNT effect on muscle stem cells remains not well defined. This study aims at clarifying the impact of BoNT on growing muscles (1) by analyzing the in vitro effect of BoNT on satellite cell (SC)-derived myoblasts and fibroblasts obtained from medial gastrocnemius microbiopsies collected in young BoNT-naïve children (t0) compared to age ranged typically developing children; (2) by following the effect of in vivo BoNT administration on these cells obtained from the same children with CP at 3 (t1) and 6 (t2) months post BoNT; (3) by determining the direct effect of a single and repeated in vitro BoNT treatment on neuromuscular junctions (NMJs) differentiated from hiPSCs. In vitro BoNT did not affect myogenic differentiation or collagen production. The fusion index significantly decreased in CP at t2 compared to t0. In NMJ cocultures, BoNT treatment caused axonal swelling and fragmentation. Repeated treatments impaired the autophagic-lysosomal system. Further studies are warranted to understand the long-term and collateral effects of BoNT in the muscles of children with CP.

Intramuscular Neural Distribution of the Gastrocnemius for Botulinum Neurotoxin Injection: Application to Cosmetic Calf Shaping

PURPOSE

Anatomical landmarks can provide vital information on the distribution of nerves in the gastrocnemius muscle. We aimed to provide an anatomical perspective on appropriate locations for botulinum neurotoxin (BoNT) injections in the medial and lateral parts of the gastrocnemius for calf shaping.

MATERIALS AND METHODS

A modified Sihler's method was applied to both the medial and lateral parts of the gastrocnemius muscles (16 specimens). Intramuscular neural distributions were revealed by dissecting along a transverse line crossing the fibular head and superior margin of the calcaneal tuberosity.

RESULTS

The intramuscular neural distribution for the medial and lateral parts of the gastrocnemius had the greatest arborized patterns in the 7/10-8/10 section of the medial head and 7.5/10-8.5/10 section of the lateral part of the gastrocnemius.

CONCLUSION

We propose that BoNT injections should be directed to the 7/10-8/10 section of the medial head and the 7.5/10-8.5/10 section of the lateral part of the gastrocnemius. Following our guidelines, clinicians can ensure satisfactory results with the use of minimal doses to limit adverse effects, such as gait disturbance, antibody production, and bruising, due to multiple injections. The results can also be altered and applied to electromyography.

Neuromuscular compartmentation of the subscapularis muscle and its clinical implication for botulinum neurotoxin injection

In this study, using immunohistochemistry with fresh cadavers, deliberate histological profiling was performed to determine which fibers are predominant within each compartment. To verify the fascial compartmentation of the SSC and elucidate its histological components of type I and II fibers using macroscopic, histological observation and cadaveric simulation for providing an anatomical reference of efficient injection of the BoNT into the SSC. Seven fixed and three fresh cadavers (six males and four females; mean age, 82.5 years) were used in this study. The dissected specimens revealed a distinct fascia demarcating the SSC into the superior and inferior compartments. The Sihler's staining revealed that the upper and lower subscapular nerves (USN and LSN) innervated the SSC, with two territories distributed by each nerve, mostly corresponding to the superior and inferior compartments of the muscle, although there were some tiny communicating twigs between the USN and LSN. The immunohistochemical stain revealed the density of each type of fiber. Compared with the whole muscle area, the densities of the slow-twitch type I fibers were 22.26 ± 3.11% (mean ± SD) in the superior and 81.15 ± 0.76% in the inferior compartments, and the densities of the fast-twitch type II fiber were 77.74% ± 3.11% in the superior and 18.85 ± 0.76% in the inferior compartments. The compartments had different proportions of slow-fast muscle fibers, corresponding to the functional differences between the superior compartment as an early-onset internal rotator and the inferior compartment as a durable stabilizer of the glenohumeral joint.

Botulinum neurotoxin injection in the deltoid muscle: application to cosmetic shoulder contouring

BACKGROUND AND OBJECTIVES

This study describes the intramuscular nerve branching of the deltoid muscle in relation to shoulder surface anatomy, with the aim of providing essential information regarding the most appropriate sites for botulinum neurotoxin injection during shoulder line contouring.

METHODS

The modified Sihler's method was used to stain the deltoid muscles (16 specimens). The intramuscular arborization areas of the specimens were demarcated using the marginal line of the muscle origin and the line connecting the anterior and posterior upper edges of the axillary region.

RESULTS

The intramuscular neural distribution of the deltoid muscle had the greatest arborization patterns in the area between the horizontal 1/3 and 2/3 lines of the anterior and posterior deltoid bellies, and 2/3 to axillary line in middle deltoid bellies. The greatest part of the posterior circumflex artery and axillary nerve ran below the areas with the highest aborizations.

CONCLUSION

We propose that botulinum neurotoxin injections should be administered in the area between the 1/3 and 2/3 lines of the anterior and posterior deltoid bellies, and 2/3 to axillary line on middle deltoid bellies. Accordingly, clinicians will ensure minimal dose injections and fewer adverse effects of the botulinum neurotoxin injection. Deltoid intramuscular injections, such as vaccines and trigger point injections, should ideally be adapted according to our results.

Anatomical analysis of the intramuscular distribution patterns of the levator scapulae and the clinical implications for pain management

PURPOSE

The present study aimed to demonstrate the intramuscular nerve distribution of the levator scapulae muscle that is responsible for pain and to use this anatomic data to propose possible injection sites.

METHODS

Twenty levator scapulae muscles were dissected from 16 Korean embalmed cadavers. The intramuscular nerve distribution of the levator scapulae muscle was identified by whole-mount nerve staining to preserve and stain the nerve fibers without damage.

RESULTS

The posterior ramus of spinal nerves C3, C4, and C5 innervated the levator scapulae muscles. When the origin and insertion of the muscle were set to 0% and 100%, respectively, most of the intramuscular nerve terminals were located between 30 and 70%. This area may correspond to the cricoid cartilage of the sixth cervical vertebra.

CONCLUSION

Most intramuscular nerve terminals can be found in the middle and distal portions of the levator scapulae muscle. Our findings improve our understanding of the intramuscular nerve distribution of the levator scapulae muscle and will aid in pain management in clinical practice.

Anatomical Proposal for Botulinum Neurotoxin Injection Targeting the Platysma Muscle for Treating Platysmal Band and Jawline Lifting: A Review

The platysma muscle is a thin superficial muscle that covers the entire neck and lower part of the face. The platysma muscle is the primary target muscle for botulinum neurotoxin injection therapy aimed at treating platysmal band and lower facial lifting. In the procedure of botulinum neurotoxin injection therapy, a lack of knowledge of the anatomy of the platysma muscle and the properties of botulinum neurotoxin can lead to side effects such as dysphagia, dysphonia, and weakness of the neck muscles. Anatomically safe injection sites have been proposed for the platysma muscle, and the appropriate injection technique has been reviewed. We proposed optimal injection sites based on the external anatomical features of the mandible. The aim of these proposal was to standardize the procedure for the effective use of botulinum neurotoxin injections by minimizing the dose unit and injection points and thereby preventing adverse events.

Ultrasonographic observation of the masseter muscle after injection of different botulinum toxin type A

BACKGROUND

Botulinum toxin type A (BoNT-A) injection is a popular cosmetic procedure in East Asian countries, and there are multiple types of toxins on the market. Whether different toxin types induce different changes in the masseter has not been studied.

OBJECTIVE

We aimed to investigate and compare the changes induced by injection of different types of BoNT-A in the masseter.

METHODS

Upon retrospective review of clinical records and routine ultrasound examination results of patients who underwent BoNT-A injection, four groups were set for comparison: unapproved toxin, OnabotulinumtoxinA, LanbotulinumtoxinA, and non-injected. Clinical records and ultrasound images were collected. Ultrasound images were taken in both horizontal and coronal planes. Elasticity of the masseter muscle was also investigated by measuring the surface wave speed.

RESULTS

A total of 24 patients were included (six patients per group). All patients were young females. For the non-injected group, the deep inferior tendon was clear and the muscle bundles were arranged, with little fibrous content. Patients who received unapproved toxin injection showed highly disarranged muscle and fiber bundles, with much fiber content present. The changes in OnabotulinumtoxinA and LanbotulinumtoxinA groups were in between those in the non-injected and unapproved toxin groups. Muscle rigidity was the highest in the unapproved toxin group, and generally higher in injected groups compared with the non-injected group.

CONCLUSION

Different types of BoNT-A may induce different changes in the masseter.

3D synchrotron imaging of muscle tissues at different atrophic stages in stroke and spinal cord injury: a proof-of-concept study

Synchrotron X-ray computed tomography (SXCT) allows 3D imaging of tissue with a very large field of view and an excellent micron resolution and enables the investigation of muscle fiber atrophy in 3D. The study aimed to explore the 3D micro-architecture of healthy skeletal muscle fibers and muscle fibers at different stages of atrophy (stroke sample = muscle atrophy; spinal cord injury (SCI) sample = severe muscle atrophy). Three muscle samples: a healthy control sample; a stroke sample (atrophic sample), and an SCI sample (severe atrophic sample) were imaged using SXCT, and muscle fiber populations were segmented and quantified for microarchitecture and morphology differences. The volume fraction of muscle fibers was 74.7%, 70.2%, and 35.3% in the healthy, stroke (atrophic), and SCI (severe atrophic) muscle fiber population samples respectively. In the SCI (severe atrophic sample), 3D image analysis revealed fiber splitting and fiber swelling. In the stroke sample (atrophic sample) muscle fiber buckling was observed but was only visible in the 3D analysis. 3D muscle fiber population analysis revealed new insights into the different stages of muscle fiber atrophy not to be observed nor quantified with a 2D histological analysis including fiber buckling, loss of fibers and fiber splitting.

The Short-Term Impact of Botulinum Neurotoxin-A on Muscle Morphology and Gait in Children with Spastic Cerebral Palsy

Children with spastic cerebral palsy (SCP) are often treated with intramuscular Botulinum Neurotoxin type-A (BoNT-A). Recent studies demonstrated BoNT-A-induced muscle atrophy and variable effects on gait pathology. This group-matched controlled study in children with SCP compared changes in muscle morphology 8-10 weeks post-BoNT-A treatment (n = 25, median age 6.4 years, GMFCS level I/II/III (14/9/2)) to morphological changes of an untreated control group (n = 20, median age 7.6 years, GMFCS level I/II/III (14/5/1)). Additionally, the effects on gait and spasticity were assessed in all treated children and a subgroup (n = 14), respectively. BoNT-A treatment was applied following an established integrated approach. Gastrocnemius and semitendinosus volume and echogenicity intensity were assessed by 3D-freehand ultrasound, spasticity was quantified through electromyography during passive muscle stretches at different velocities. Ankle and knee kinematics were evaluated by 3D-gait analysis. Medial gastrocnemius (p = 0.018, -5.2%) and semitendinosus muscle volume (p = 0.030, -16.2%) reduced post-BoNT-A, but not in the untreated control group, while echogenicity intensity did not change. Spasticity reduced and ankle gait kinematics significantly improved, combined with limited effects on knee kinematics. This study demonstrated that BoNT-A reduces spasticity and partly improves pathological gait but reduces muscle volume 8-10 weeks post-injections. Close post-BoNT-A follow-up and well-considered treatment selection is advised before BoNT-A application in SCP.

Novel Anatomical Proposal for Botulinum Neurotoxin Injection Targeting Lateral Canthal Rhytids

Botulinum neurotoxin injections near the lateral canthal rhytids are commonly used in cosmetic settings; however, there is a lack of thorough anatomical knowledge, and an effective way to treat them with accumulating knowledge is needed. The anatomical characteristics concerning the injection of botulinum neurotoxin into the orbicularis oculi muscle were evaluated in this review. Current knowledge on the identification of botulinum neurotoxin injection points from recent anatomical research was assessed. The lateral canthal lines are involved with the orbicularis oculi muscle and nearby anatomical structures, and the injection points can be more precisely defined. The best possible injection sites were provided, and the injection procedure was described. This review proposes evidence for injection sites associated with the surface anatomy of the orbicularis oculi muscles to enhance the effectiveness of easing lateral canthal rhytids.

Guidelines for botulinum neurotoxin injection for facial contouring

SUMMARY

The hypertrophied temporalis and masseter muscles give a muscular shaped and bulky contour to the face. Botulinum neurotoxin injection methods are commonly used for facial contouring; however, adverse effects have been reported owing to a lack of delicate anatomical information. The anatomical considerations when injecting botulinum neurotoxin into the temporalis and masseter muscles have been reviewed in the present study. Current knowledge on the localization of the botulinum neurotoxin injection point with more recent anatomical dissection and modified Sihler's staining procedures was assessed. We found that for the muscles, the injection point can be more precisely demarcated. Optimal injection sites are presented for the temporalis and masseter muscles, and the injection technique has been suggested. We propose the optimal injection sites in relation to external anatomical landmarks for the frequently injected muscles of the face to facilitate the efficiency of botulinum neurotoxin injections. In addition, these guidelines would aid in more precise practice without the adverse effects of botulinum neurotoxin.

Botox Injections in Paraspinal Muscles Result in Low Maximal Specific Force and Shortening Velocity in Fast but Not Slow Skinned Muscle Fibers

STUDY DESIGN

Basic science, experimental animal study.

OBJECTIVE

To determine the effects of Botulinum toxin type A (BTX-A) injections on the mechanical properties of skinned muscle fibers (cells) of rabbit paraspinal muscles.

SUMMARY OF BACKGROUND DATA

BTX-A has been widely used in the treatment of disorders of muscle hyperactivity, such as spasticity, dystonia, and back pain. However, BTX-A injection has been shown to cause muscle atrophy, fat infiltration, and decreased force output in target muscles, but its potential effects on the contractile machinery and force production on the cellular level remain unknown.

METHODS

Nineteen-month-old, male New Zealand White Rabbits received either saline or BTX-A injections into the paraspinal muscles, equally distributed along the left and right sides of the spine at T12, L1, and L2 at 0, 8, 12, 16, 20, and 24 weeks. Magnetic resonance imaging was used to quantify muscle crosssectional area and structural changes before and at 28 weeks following the initial injection. Skinned fibers isolated from the paraspinal muscles were tested for their active and passive force-length relationships, unloaded shortening velocity, and myosin heavy chain isoforms.

RESULTS

BTX-A injections led to significant fat infiltration within the injected muscles and a greater proportion of IIa to IIx fibers. Isolated fast fibers from BTX-A injected animals had lower active force and unloaded shortening velocity compared with fibers from saline-injected control animals. Force and velocity properties were not different between groups for the slow fibers.

CONCLUSION

Injection of BTX-A into the paraspinal rabbit muscles leads to significant alterations in the contractile properties of fast, but not slow, fibers.Level of Evidence: N/A.

Novel Anatomical Guidelines on Botulinum Neurotoxin Injection for Wrinkles in the Nose Region

Botulinum neurotoxin injection surrounding the nose area is frequently used in aesthetic settings. However, there is a shortage of thorough anatomical understanding that makes it difficult to treat wrinkles in the nose area. In this study, the anatomical aspects concerning the injection of botulinum neurotoxin into the nasalis, procerus, and levator labii superioris alaeque muscles are assessed. In addition, the present knowledge on localizing the botulinum neurotoxin injection point from a newer anatomy study is assessed. It was observed that, for the line-associated muscles in the nose region, the injection point may be more precisely defined. The optimal injection sites are the nasalis, procerus, and levator labii superioris alaeque muscles, and the injection technique is advised. We advise the best possible injection sites in association with anatomical standards for commonly injected muscles to increase efficiency in the nose region by removing the wrinkles. Similarly, these suggestions support a more precise procedure.

The Development of Hindlimb Postural Asymmetry Induced by Focal Traumatic Brain Injury Is Not Related to Serotonin 2A/C Receptor Expression in the Spinal Cord

Brain injury and stroke are leading causes of adult disability. Motor deficits are common problems, and their underlying pathological mechanisms remain poorly understood. The serotoninergic system is implicated in both functional recovery from and the occurrence of spasticity after injuries to the central nervous system. This study, which was conducted on rats, investigated the development of limb postural changes and their relationship to the expression of serotonin (5-HT) 2A and 2C receptors in the spinal cord in the 4 weeks after focal traumatic brain injury (TBI) to the right hindlimb sensorimotor cortex. The limb motor deficits were assessed by measuring gait pattern changes during walking and hindlimb postural asymmetry at different time intervals (3−28 days) after surgery. The expressions of the 5-HT2A and 2C receptors in the lumbar spinal cord were investigated using immunohistochemistry. The results showed that all the rats with TBI, independently of the duration of the interval, displayed postural asymmetry with flexion on the contralateral (left) side (>2 mm), while the sham-operated rats showed no apparent postural asymmetry. The TBI rats also had longer stride lengths during walking in both their hindlimbs and their forelimbs compared with the sham rats. For both the TBI and the sham rats, the hind-paw placement angles were larger on the contralateral side in some of the groups. Compared to the sham-operated rats, the 5-HT2A and 2C receptor expression did not significantly change on either side of the lumbar spinal cords of the TBI rats in any of the groups. These results suggest that focal TBI can induce motor deficits lasting a relatively long time, and that these deficits are not related to the expression of the 5-HT2A and 2C receptors in the spinal cord.

Pore Size-Dependent Stereoscopic Hydrogels Enhance the Therapeutic Efficiency of Botulinum Toxin for the Treatment of Nerve-Related Diseases

Botulinum toxin (BoNT) is a major neurotherapeutic protein that has been used at low doses for diverse pharmacological applications. However, the pleiotropic effect of BoNT depends on multiple periodic injections owing to its rapid elimination profile, short-term therapeutic effect, and high mortality rate when administered at high doses. In addition to low patient compliance, these drawbacks represent the significant challenges that limit the further clinical use of BoNT. This study developed a new hydrogel-based single dosage form of BoNT by employing a one-step cross-linking chemistry. Its controlled porous structures and composition facilitated uniform drug distribution inside the hydrogel and controllable release of BoNT mediated by slow diffusion. A single dose remained stable for at least 2.5 months and showed sustained effect for at least 20 weeks, meeting the requirements for a single-dose form of BoNT. Additionally, this dosage form was evaluated as safe from all aspects of toxicology. This delivery system resulted in a 100% survival rate after administering a BoNT dose of 30 units, while a dose of more than 5 units of naked BoNT caused a 100% mortality rate within a few days. Overall, this strategy could provide patients with the first single-dose treatment option of BoNT and improve their quality of life.

Anatomical Proposal for Botulinum Neurotoxin Injection for Glabellar Frown Lines

Botulinum neurotoxin injection for treating glabellar frown lines is a commonly used method; however, side effects, such as ptosis and samurai eyebrow, have been reported due to a lack of comprehensive anatomical knowledge. The anatomical factors important for the injection of the botulinum neurotoxin into the corrugator supercilii muscle has been reviewed in this study. Current understanding on the localization of the botulinum neurotoxin injection point from newer anatomy examination was evaluated. We observed that for the glabellar-frown-line-related muscles, the injection point could be more accurately demarcated. We propose the injection method and the best possible injection sites for the corrugator supercilii muscle. We propose the optimal injection sites using external anatomical landmarks for the frequently injected muscles of the face to accelerate effective glabellar frown line removal. Moreover, these instructions would support a more accurate procedure without adverse events.

Reduced Cross-Sectional Muscle Growth Six Months after Botulinum Toxin Type-A Injection in Children with Spastic Cerebral Palsy

Botulinum Neurotoxin type-A (BoNT-A) injections are widely used as first-line spasticity treatment in spastic cerebral palsy (SCP). Despite improved clinical outcomes, concerns regarding harmful effects on muscle morphology have been raised. Yet, the risk of initiating BoNT-A to reduce muscle growth remains unclear. This study investigated medial gastrocnemius (MG) morphological muscle growth in children with SCP (n = 26, median age of 5.2 years (3.5)), assessed by 3D-freehand ultrasound prior to and six months post-BoNT-A injections. Post-BoNT-A MG muscle growth of BoNT-A naive children (n = 11) was compared to (a) muscle growth of children who remained BoNT-A naive after six months (n = 11) and (b) post-BoNT-A follow-up data of children with a history of BoNT-A treatment (n = 15). Six months after initiating BoNT-A injection, 17% decrease in mid-belly cross-sectional area normalized to skeletal growth and 5% increase in echo-intensity were illustrated. These muscle outcomes were only significantly altered when compared with children who remained BoNT-A naive (+4% and -3%, respectively, p < 0.01). Muscle length growth persevered over time. This study showed reduced cross-sectional growth post-BoNT-A treatment suggesting that re-injections should be postponed at least beyond six months. Future research should extend follow-up periods investigating muscle recovery in the long-term and should include microscopic analysis.

High Precision Use of Botulinum Toxin Type A (BONT-A) in Aesthetics Based on Muscle Atrophy, Is Muscular Architecture Reprogramming a Possibility? A Systematic Review of Literature on Muscle Atrophy after BoNT-A Injections

Improvements in Botulinum toxin type-A (BoNT-A) aesthetic treatments have been jeopardized by the simplistic statement: “BoNT-A treats wrinkles”. BoNT-A monotherapy relating to wrinkles is, at least, questionable. The BoNT-A mechanism of action is presynaptic cholinergic nerve terminals blockage, causing paralysis and subsequent muscle atrophy. Understanding the real BoNT-A mechanism of action clarifies misconceptions that impact the way scientific productions on the subject are designed, the way aesthetics treatments are proposed, and how limited the results are when the focus is only on wrinkle softening. We designed a systematic review on BoNT-A and muscle atrophy that could enlighten new approaches for aesthetics purposes. A systematic review, targeting articles investigating BoNT-A injection and its correlation to muscle atrophy in animals or humans, filtered 30 publications released before 15 May 2020 in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Histologic analysis and histochemistry showed muscle atrophy with fibrosis, necrosis, and an increase in the number of perimysial fat cells in animal and human models; this was also confirmed by imaging studies. A significant muscle balance reduction of 18% to 60% after single or seriated BoNT-A injections were observed in 9 out of 10 animal studies. Genetic alterations related to muscle atrophy were analyzed by five studies and showed how much impact a single BoNT-A injection can cause on a molecular basis. Seriated or single BoNT-A muscle injections can cause real muscle atrophy on a short or long-term basis, in animal models and in humans. Theoretically, muscular architecture reprogramming is a possible new approach in aesthetics.

Immunogenicity of botulinum toxin

Botulinum toxin treatment is the most common non-surgical cosmetic treatment. Although there are many available treatments using botulinum toxin, their effects are temporary and repeated injections are required. These frequent injections can trigger an immunological response. In addition, botulinum toxin acts as an antigen in the body; thus, its effect disappears progressively due to this immunological reaction, which may cause treatment failure. Active botulinum toxin consists of a core neurotoxin and complexing proteins, the exact effects of which remain unclear. However, the complexing proteins are closely related to the immune response and the formation of neutralizing antibodies. Since neutralizing antibodies can lead to treatment failure, their formation should be prevented. Furthermore, various methods of detecting neutralizing antibodies have been used to predict treatment failure.

Therapeutic efficacy of new botulinum toxin identified in CCUG 7968 strain

Botulinum neurotoxin type A (BoNT/A) induces muscle atrophy by cleaving synaptosomal-associated protein 25. Thus, BoNT/A has been actively utilized for the treatment of masseter and gastrocnemius hypertrophy. In this study, INI101 toxin was newly identified from the CCUG 7968 strain, and its therapeutic efficacy was evaluated both in vitro and in vivo. The INI101 toxin showed identical genetic sequence, amino acid sequence, and protein subunit composition to BoNT/A produced from strain Hall A. Electromyography (EMG), and immunofluorescence staining demonstrated that INI101 (at 2 ~ 8 U/rat) effectively blocked the neuromuscular junction with no toxicity in a rat model. The EMG results showed INI101 toxin-induced weight loss and volume reduction of the gastrocnemius, similar to the effects of Botox® (BTX). Histological and immunofluorescence staining was consistent with this EMG result, showing that INI101 toxin caused muscle fiber reduction in the gastrocnemius. Notably, INI101 toxin diffused less into adjacent muscle tissue than BTX, indicating that INI101 toxin may reduce potential side effects due to diffusion into normal tissues. INI101 toxin isolated from the novel strain CCUG 7968 is a newly identified meaningful biopharmaceutical comparable to the conventional BoNT/A in the medical field. KEY POINTS: • Botulinum neurotoxin type A (BoNT/A, INI101) was identified from the CCUG 7968 strain. • INI101 toxin showed similar safety and therapeutic efficacy comparable to conventional BoNT/A both in vitro and in vivo. • INI101 toxin is a meaningful biopharmaceutical comparable to the conventional BoNT/A in the medical field.

Restoration of Heel-Toe Gait Patterns for the Prevention of Asymmetrical Hip Internal Rotation in Patients with Unilateral Spastic Cerebral Palsy

Forward modelling has indicated hip internal rotation as a secondary physical effect to plantar flexion under load. It could therefore be of interest to focus the treatment for patients with unilateral spastic cerebral palsy on achieving a heel-toe gait pattern, to prevent development of asymmetrical hip internal rotation. The aim of this preliminary retrospective cohort investigation was to evaluate the effect of restoring heel-toe gait, through use of functional orthoses, on passive hip internal rotation. In this study, the affected foot was kept in an anatomically correct position, aligned to the leg and the gait direction. In case of gastrosoleus shortness, a heel raise was attached to compensate for the equinus and yet to provide heel-floor contact (mean equinus = -2.6 degrees of dorsiflexion). Differences in passive hip internal rotation between the two sides were clinically assessed while the hip was extended. Two groups were formed according to the achieved correction of their gait patterns through orthotic care: patients with a heel-toe gait (with anterograde rocking) who wore the orthosis typically for at least eight hours per day for at least a year, or patients with toe-walking (with retrograde rocking) in spite of wearing the orthosis who used the orthosis less in most cases. A Student's t-test was used to compare the values of clinically assessed passive hip rotation (p < 0.05) between the groups and the effect size (Hedges' g) was estimated. Of the 70 study participants, 56 (mean age 11.5 y, majority GMFCS 1, similar severity of pathology) achieved a heel-toe gait, while 14 remained as toe-walkers. While patients with heel-toe gait patterns showed an almost symmetrical passive hip internal rotation (difference +1.5 degrees, standard deviation 9.6 degrees), patients who kept toe-walking had an increased asymmetrical passive hip internal rotation (difference +10.4 degrees, standard deviation 7.5 degrees; p = 0.001, Hedges's g = 0.931). Our clinical findings are in line with the indications from forward modelling that treating the biomechanical problem might prevent development of a secondary deformity. Further prospective studies are needed to verify the presented hypothesis.

Toxic potential of botulinum toxin type A on senescence in a Drosophila melanogaster model

Botulinum toxin type-A (BoNT/A) application, especially neurological disorders, has been spread nowadays while it may cause side effects. The current study aimed to assess the BoNT/A dose-dependent effect on induction of aging in the Drosophila melanogaster model. The third instar larvae of Drosophila melanogaster were exposed to ¼ LC₅₀, ½ LC₅₀, and LC₅₀ of BoNT/A in the Drosophila diet for 48 h while H₂O₂ 1% was used as a positive control. After the exposure time, some larvae were collected for molecular study, including gene expression analysis, comet assay, oxidative stress markers, and the phenotype changes. BoNT/A induced dose-dependent cytotoxicity, elevated reactive oxygen species (ROS) levels, and superoxide dismutase (SOD) enzyme activity. In addition, it caused DNA damage and activated caspase-3 and -9, and reduced the body size of the fly, especially in high doses. In line with the purpose of the study, aging markers, including β-galactosidase (β-gal), p16, p21, p38, and p53, were up-regulated by BoNT/A low dose. BoNT/A activates the aging pathway in the low dose, and increasing the dose induces toxicity, including oxidative stress, DNA damage, and apoptosis.

Intramuscular BoNT/A injections cause an inflammatory response in the muscle tissue of rats

Objectives

The purpose of the present study was to investigate whether intramuscular BoNT/A injections cause an systemic inflammatory response and a local inflammatory response in the muscle tissue.

Methods

Thirty-two male Sprague Dawley rats treated with BoNT/A (i.m., 1IU) were divided in four groups, depending on the time of BoNT/A injection (2 days before, 1, 2, and 4 weeks before the experiment). Bio-Plex Pro Rat Cytokine 23-plex Multiplex Assay (Bio-Rad, USA).

Results

Systemic inflammation: 17 cytokines (IL1-α ( p = 0.005), IL-1β ( p = 0.01), IL-2 ( p = 0.04), IL-4 ( p = 0.03), IL-6 ( p = 0.03), IL-10 ( p = 0.02), IL12(p70) ( p = 0.03), IL-13 ( p = 0.04), IL-17 ( p = 0.03), GM-CSF ( p = 0.03), INF-γ ( p = 0.03), MIP-1α ( p = 0.03), MIP-3α ( p = 0.04), RANTES ( p = 0.001), TNF-α ( p = 0.04), vascular endothelial growth factor ( p = 0.03), and MCP-1 ( p = 0.02)) showed significantly higher expression levels 2 days after intramuscular BoNT/A injections compared to other time points (1, 2, and 4 weeks). Local inflammation: 12 cytokines (IL-1β ( p = 0.02), IL-6 ( p = 0.002), IL-10 ( p = 0.02), IL-13 ( p = 0.04), IL-17 ( p = 0.02), TNF-α ( p = 0.001), GM-CSF ( p = 0.01), M-CSF ( p = 0.04), MIP-1α ( p = 0.04), MIP-3α ( p = 0.002), RANTES ( p = 0.02), and MCP-1( p = 0.004)) showed higher expression levels 2 and/or 4 weeks after intramuscular BoNT/A injections compared to the other time points (2 days and 1 week).

Conclusion

Intramuscular BoNT/A injections result in a rapid systemic inflammatory response that only lasts a couple of days. At the same time, intramuscular BoNT/A injections cause an inflammatory response locally in the muscle with significantly higher cytokine levels 2 and/or 4 weeks after injections.

Guidelines for botulinum neurotoxin injections in piriformis syndrome

BACKGROUND

The piriformis muscle is normally involved in piriformis syndrome and can be treated with botulinum neurotoxin using several different injection methods. However, definitive injection guidelines for the muscle have not been reported previously.

AIMS

This study aimed to determine the ideal area for injections based on the intramuscular nerve distribution as obtained using a modified Sihler's staining technique.

MATERIALS AND METHODS

A modified Sihler's method was applied to the piriformis muscle in 15 specimens. The intramuscular arborization areas were identified based on two anatomical landmarks: (a) the lateral border of the sacrum bone and (b) the greater trochanter.

RESULTS

The nerve entry point for both piriformis muscles was found in the area between the lateral border of the sacrum and one-fifth of the distance toward the greater trochanter. The intramuscular nerve distribution for the piriformis muscle had the largest arborization patterns between one-fifth and two-fifths of the distance from the sacrum to the greater trochanter. The piriformis muscle was tendinous from two-fifths of the distance to the greater trochanter.

DISCUSSION

This study has yielded suggested optimal injection locations for the piriformis muscle relative to external anatomical landmarks.

CONCLUSION

Clinicians can use these guidelines to ensure the effectiveness of not only botulinum neurotoxin injections but also other agents such as steroids, anesthetics, and normal saline. These guidelines will also help to avoid adverse outcomes of injection treatments.

Intramuscular Injection of BOTOX® Boosts Learning and Memory in Adult Mice in Association with Enriched Circulation of Platelets and Enhanced Density of Pyramidal Neurons in the Hippocampus

BOTOX® is a therapeutic form of botulinum neurotoxin. It acts by blocking the release of acetylcholine (ACh) from the synaptic vesicles at the neuromuscular junctions, thereby inhibiting the muscle contraction. Notably, many neurological diseases have been characterized by movement disorders in association with abnormal levels of ACh. Thus, blockade of aberrant release of ACh appears to be a potential therapeutic strategy to mitigate many neurological deficits. BOTOX® has widely been used to manage a number of clinical complications like neuromuscular disorders, migraine and neuropathic pain. While the beneficial effects of BOTOX® against movement disorders have extensively been studied, its possible role in the outcome of cognitive function remains to be determined. Therefore, we investigated the effect of BOTOX® on learning and memory in experimental adult mice using behavioural paradigms such as open field task, Morris water maze and novel object recognition test in correlation with haematological parameters and histological assessments of the brain. Results revealed that a mild dose of BOTOX® treatment via an intramuscular route in adult animals improves learning and memory in association with increased number of circulating platelets and enhanced structural plasticity in the hippocampus. In the future, this minimally invasive treatment could be implemented to ameliorate different forms of dementia resulting from abnormal ageing and various neurocognitive disorders including Alzheimer's disease (AD).

Anatomical guide for botulinum neurotoxin injection: Application to cosmetic shoulder contouring, pain syndromes, and cervical dystonia

INTRODUCTION

This study proposes an ideal botulinum toxin injection point of the trapezius muscle for shoulder line contouring, pain management, and functional impairment. This study describes the intramuscular nerve branching in the trapezius muscle, providing essential information for botulinum neurotoxin injection.

METHOD

A modified Sihler's method was performed on the trapezius muscles (16 specimens). The intramuscular arborization areas were elucidated regarding the external occipital protuberance superiorly, spinous process of the 12th thoracic vertebra inferiorly and acromion of the scapula.

RESULT

The intramuscular neural distribution for the superior, middle, and inferior regions of the trapezius muscle had the greatest arborized patterns in the horizontal 1/5-2/5 and vertical 2/10-4/10 sections, the horizontal 1/5-3/5 and vertical 4/10-5/10 sections, and the horizontal 1/5-2/5 and vertical 5/10-7/10 sections, respectively.

DISCUSSION

We propose that BoNT treatments should be directed to the horizontal 1/5-2/5 and vertical 2/10-4/10 sections of the superior trapezius, the horizontal 1/5-3/5 and vertical 4/10-5/10 sections of the middle trapezius and the horizontal 1/5-2/5 and vertical 5/10-7/10 sections of the inferior trapezius. Additionally, injective treatment at the horizontal 2/5-3/5 and vertical 2/10-4/10 nerve entry points should be avoided to prevent nerve trunk damage causing paralysis. According to our guidelines, clinicians can ensure minimal dose injections and fewer adverse effects in botulinum neurotoxin injective treatment.

Investigation of Various Intramuscular Volumes Delivered to the Semimembranosus Muscle of Cavia porcellus

The goal of this study is to provide quantitative data on the ideal volume for intramuscular (IM) injections into the semimembranosus muscle of guinea pigs weighing between 320 to 410 grams. This evaluation comprised 2 experiments. The first was to assess dispersion leakage of intramuscularly injected iohexol, a radiocontrast agent commonly used in Computed Tomography (CT), based on analysis of in vivo imaging. The second used varying volumes of intramuscularly injected sodium chloride (0.9% NaCl) to assess pain and pathology associated with IM injection. Hartley guinea pigs were injected IM with varying volumes of either iohexol or sodium chloride (150, 300, 500, 1000 and 1500 μL). In the iohexol experiment, results suggest IM volumes of 150 and 300 μL remain within the target muscle. In the experiment using sodium chloride, pain and pathology did not increase as IM volume increased. The pathology noted was related to needle tract through the musculature rather than the volume size of the injectate. The results did not reveal a correlation between volume of IM 0.9% NaCl and pain levels. We conclude that volume size correlates more with precision and accuracy of delivery into the intended muscle tissue. Regarding tissue distribution, our findings also suggest that the optimal capacity for IM injection in the semimembranosus muscle should be less than 500 μL.

A pragmatic approach to Botulinum Toxin safety

Botulinum Toxin (BoNT) is widely used to treat hypertonia in pediatric patients. Although serious adverse events (AEs) occur infrequently, they can lead to significant patient morbidity and mortality. This paper will discuss potential safety risks that may affect outcomes, medical comorbidities, medication dosing, targeting techniques, and muscle morphology. It is the responsibility of the physician to discuss risks and benefits regarding the use of BoNT and mitigate risks of AEs while maximizing the effectiveness of the medication.

Botulinum Toxin Injection in Children with Hemiplegic Cerebral Palsy: Correction of Growth through Comparison of Treated and Unaffected Limbs

Botulinum toxin type A (BoNT-A) injections in children with cerebral palsy (CP) may negatively affect muscle growth and strength. We injected BoNT-A into the affected limbs of 14 children (4.57 ± 2.28 years) with hemiplegic CP and exhibiting tip-toeing gait on the affected side and investigated the morphological alterations in the medial head of the gastrocnemius muscle (GCM). We assessed thickness of the GCM, fascicle length, and fascicle angle on the affected and unaffected sides at baseline at 4 and 12 weeks after BoNT-A injections. The primary outcome measure was the change (percentage) in GCM thickness in the affected side treated with BoNT-A in comparison with the unaffected side. The percentage of treated GCM thickness became significantly thinner at 4 and 12 weeks after BoNT-A injection than baseline. However, the percentage of fascicle length and angle in treated limbs showed no significant change from baseline 4 and 12 weeks after the injection. BoNT-A injections might reduce muscle thickness in children with spastic hemiplegic CP. Fascicle length and angle might not be affected by BoNT-A injections after correction of normal growth of the children.

Biotoxins in muscle regeneration research

Skeletal muscles are characterized by their unique regenerative capacity following injury due to the presence of muscle precursor cells, satellite cells. This characteristic allows researchers to study muscle regeneration using experimental injury models. These injury models should be stable and reproducible. Variety of injury models have been used, among which the intramuscular injection of myotoxic biotoxins is considered the most common and widespread method in muscle regeneration research. By using isolated biotoxins, researchers could induce acute muscle damage and regeneration in a controlled and reproducible manner. Therefore, it is considered an easy method for inducing muscle injury in order to understand the different mechanisms involved in muscle injuries and tissue response following injury. However, different toxins and venoms have different compositions and subsequently the possible effects of these toxins on skeletal muscle vary according to their composition. Moreover, regeneration of injured muscle by venoms and toxins varies according to the target of toxin or venom. Therefore, it is essential for researcher to be aware of the mechanism and possible target of toxin-induced injury. The current paper provides an overview of the biotoxins used in skeletal muscle research.

Comparison study of the response with botulinum toxin muscle injection in the ICR mice from three different sources

Botulinum-toxin A (BoNT/A) is a widely used not only for cosmetics but also for various experimental purposes including muscle-related research. In this study, we applied BoNT/A to mouse muscle of three different sources to compare and evaluate the biological and pathological response. The three different mouse sources consist of Korl:ICR (Korea FDA source), A:ICR (USA source) and B:ICR (Japan source) which were purchased from each different vendors. To compare the responses of ICR mice with BoNT/A muscle injection, we examined the body weight, hematological and serum biochemistry analysis. Also, we evaluated the muscle change by histopathological analysis and gene expression patterns of muscle-related target by qPCR. The body weight gain was decreased in the BoNT/A-treated group compared with the control group. In clinical pathologic analysis and gene expression patterns, the data showed that the responses in the BoNT/A-treated group were similar compared with the control group. Decreased muscle fiber was observed in BoNT/A-treated group compared with control group, while Korl:ICR showed a little low response with the other mouse sources. In conclusion, our results suggest that three different sources ICR mice (Korl:ICR, A:ICR and B:ICR) have a similar biological and pathological responses in BoNT/A muscle injection.

Knee osteoarthritis induces atrophy and neuromuscular junction remodeling in the quadriceps and tibialis anterior muscles of rats

Knee osteoarthritis (KOA) is associated with muscle weakness, but it is unclear which structures are involved in the muscle changes. This study assessed morphological alterations and the expression of genes and proteins linked to muscular atrophy and neuromuscular junctions (NMJs) in KOA, induced by anterior cruciate ligament transection (ACLT) in rats. Two groups of rats were assessed: control (without intervention) and KOA (ACLT surgery in the right knee). After 8 weeks, quadriceps, tibialis anterior (TA) and gastrocnemius muscles were analyzed (area of muscle fibers, NMJ, gene and protein expression). KOA group showed atrophy in quadriceps (15.7%) and TA (33%), with an increase in atrogin-1 and muscle RING-finger protein-1 (MuRF-1). KOA group showed quadriceps NMJ remodeling (reduction area and perimeter) and decrease in NMJ diameter in TA muscle. The expression of nicotinic acetylcholine receptor (nAChR) γ-nAChR increased and that of α-nAChR and muscle specific tyrosine kinase (MuSK) declined in the quadriceps, with a decrease in ε-nAChR in TA. MuRF-1 protein expression increased in quadriceps and TA, with no changes in neural cell adhesion molecule (NCAM). In conclusion, ACLT-induced KOA promotes NMJ remodeling and atrophy in quadriceps and TA muscles, associated with inflammatory signs and changes in muscle gene and protein expression.

Muscle fibre morphology and microarchitecture in cerebral palsy patients obtained by 3D synchrotron X-ray computed tomography

BACKGROUND

Synchrotron X-ray computed tomography (SXCT) allows for three-dimensional imaging of objects at a very high resolution and in large field-of-view.

PURPOSE

The aim of this study was to use SXCT imaging for morphological analysis of muscle tissue, in order to investigate whether the analysis reveals complementary information to two-dimensional microscopy.

METHODS

Three-dimensional SXCT images of muscle biopsies were taken from participants with cerebral palsy and from healthy controls. We designed morphological measures from the two-dimensional slices and three-dimensional volumes of the images and measured the muscle fibre organization, which we term orientation consistency.

RESULTS

The muscle fibre cross-sectional areas were significantly larger in healthy participants than in participants with cerebral palsy when carrying out the analysis in three dimensions. However, a similar analysis carried out in two dimensions revealed no patient group difference. The present study also showed that three-dimensional orientation consistency was significantly larger for healthy participants than for participants with cerebral palsy.

CONCLUSION

Individuals with CP have smaller muscle fibres than healthy control individuals. We argue that morphometric measures of muscle fibres in two dimensions are generally trustworthy only if the fibres extend perpendicularly to the slice plane, and otherwise three-dimensional aspects should be considered. In addition, the muscle tissue of individuals with CP showed a decreased level of orientation consistency when compared to healthy control tissue. We suggest that the observed disorganization of the tissue may be induced by atrophy caused by physical inactivity and insufficient neural activation.

Botulinum toxin A-induced muscle paralysis stimulates Hdac4 and differential miRNA expression

At sufficient dose, intramuscular injection of Botulinum toxin A causes muscle wasting that is physiologically consistent with surgical denervation and other types of neuromuscular dysfunction. The aim of this study was to clarify early molecular and micro-RNA alterations in skeletal muscle following Botulinum toxin A-induced muscle paralysis. Quadriceps were analyzed for changes in expression of micro- and messenger RNA and protein levels after a single injection of 0.4, 2 or 4U Botulinum toxin A (/100g body weight). After injection with 2.0U Botulinum toxin A, quadriceps exhibited significant reduction in muscle weight and increased levels of ubiquitin ligase proteins at 7, 14 and 28 days. Muscle miR-1 and miR-133a/b levels were decreased at these time points, whereas a dose-responsive increase in miR-206 expression at day 14 was observed. Expression of the miR-133a/b target genes RhoA, Tgfb1 and Ctfg, and the miR-1/206 target genes Igf-1 and Hdac4, were upregulated at 28 days after Botulinum toxin A injection. Increased levels of Hdac4 protein were observed after injection, consistent with anticipated expression changes in direct and indirect Hdac4 target genes, such as Myog. Our results suggest Botulinum toxin A-induced denervation of muscle shares molecular characteristics with surgical denervation and other types of neuromuscular dysfunction, and implicates miR-133/Tgf-β1/Ctfg and miR-1/Hdac4/Myog signaling during the resultant muscle atrophy.

A comparison study of prabotulinumtoxinA vs onabotulinumtoxinA in myostatin-deficient mice with muscle hypertrophy

Botulinum toxin A (BoNT-A) is used clinically for various muscle disorders and acts by preventing the release of the neurotransmitter acetylcholine into the synapse space. Here, we compared the efficacy of prabotulinumtoxinA (PRA) and onabotulinumtoxinA (ONA) for the reduction in hypertrophy in myostatin-deficient (Mstn^-/- ) mice. Two different BoNT-A products (2.5, 10 and 25 U/kg) were injected to paralyse the hindlimb for 2 months, after which sciatic nerve conduction study, 3D micro-CT, haematoxylin and eosin (H&E) and dystrophin staining were conducted. Administration of BoNT-A products induced denervation-mediated atrophy and alleviated muscle hypertrophy generated in Mstn^-/- mice. The present study revealed that each BoNT-A regulates skeletal muscle size, myofibre number and myofibre diameter in Mstn^-/- mice. The potential applicability of BoNT-A for the treatment of rare muscle hypertrophic diseases was demonstrated. Compared with ONA, PRA had a comparable ability to act in the local area.