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.

Ultrasonographic study and anatomical guidelines for botulinum neurotoxin injection into the parotid gland.

Benign enlargement of the parotid gland hypertrophy results in a bulky lateral facial contour and esthetic appearance. This study aimed to determine the depth from the skin surface to the parotid fascia, which encompasses the parotid gland. The anatomical properties of the parotid glands were evaluated in 40 patients using ultrasonography. An up-to-date understanding of the localization of botulinum neurotoxin (BoNT) injection based on anatomy could lead to better localization of the injection into the parotid gland through morphological measurements using data previously published from cadaveric studies. Measurement using the otobasion inferius as a landmark revealed parotideomasseteric fascia thickness averaging 4-6 mm from the skin surface, with the parotid gland extending approximately 15 mm anteriorly. Analysis showed a 3-7 mm thickness range, indicating an optimal injection depth for safety and efficacy in BoNT procedures. Utilizing the otobasion inferius as an anatomical landmark offers a practical approach for measuring parotideomasseteric fascia thickness, addressing cadaveric study limitations. These guidelines aim to maximize the effects of BoNT therapy, which can be useful in clinical settings, by minimizing its deleterious effects.

Anatomical Guidelines and Technical Tips for Neck Aesthetics with Botulinum Toxin.

Botulinum toxin can be used for various purposes to enhance neck aesthetics, addressing concerns such as platysmal bands, optimizing the cervicomental angle, preventing worsening of horizontal neckline and decolletage lines during aging, submandibular gland hypertrophy, and hypertrophied superior trapezius muscle. Understanding the anatomy of muscles such as the trapezius, platysma, and submandibular gland is crucial for achieving desirable outcomes with botulinum toxin administration. Techniques for injecting botulinum toxin into these muscles are discussed, emphasizing safety and efficacy. Specific injection points and methods are detailed for treating platysmal bands, optimizing the cervicomental angle, addressing submandibular gland hypertrophy, and managing hypertrophied superior trapezius muscle. Careful consideration of anatomical landmarks and potential complications is essential for successful botulinum toxin injections in these areas.

Review of the Adverse Effects Associated with Dermal Filler Treatments: Part I Nodules, Granuloma, and Migration.

The increase in the use of filler treatments within minimally invasive cosmetic surgery has correspondingly escalated the variety and frequency of associated side effects. Initially, unregulated procedures led to primary side effects such as infections, foreign body reactions, and granuloma formation. However, severe vascular complications like skin and tissue necrosis and blindness have emerged as recognized risks. Side effects from filler treatments can range from mild to life-threatening, including edema, pain, tenderness, numbness, bleeding, bruising, hematoma, redness, erythema, pigmentation, allergic reactions, itching, pruritus, the Tyndall effect, asymmetry, irregularity, migration, skin and soft tissue infections, nodules, granulomas, and vascular compromise. These side effects are categorized into early and delayed types. Many complications, particularly those related to vascular abnormalities, are frequently linked to procedural issues, emphasizing the importance of understanding filler properties, injection techniques, and facial anatomy. Preventing side effects is ideal, but early detection and treatment are crucial. Recognizing potential side effects based on their timing and understanding appropriate preemptive treatment methods is essential. This discussion addresses non-vascular side effects, highlighting their onset, symptoms, and management strategies. The comprehensive understanding and careful management of these side effects are vital for minimizing complications and ensuring patient safety in filler treatments.

Adverse Effects Associated with Dermal Filler Treatments: Part II Vascular Complication.

Vascular complications arising from dermal filler treatments pose significant risks, including ischemia, tissue necrosis, and severe outcomes like blindness and pulmonary embolism. This study investigates the mechanisms of vascular complications, categorizing them into extravascular compression and intravascular emboli. Extravascular compression occurs when injected fillers compress adjacent blood vessels, leading to ischemia and potential necrosis, while intravascular emboli result from fillers entering blood vessels, causing blockages. The study emphasizes the importance of anatomical knowledge, careful injection techniques, and early intervention. Management strategies include the use of hyaluronidase to dissolve HA fillers, vasodilators to improve blood circulation, and hyperbaric oxygen therapy. The regions most susceptible to complications align with major arterial pathways, particularly the nasolabial folds and nasal region. The study also highlights the need for meticulous injection techniques, the use of cannulas over needles in high-risk areas, and the aspiration test to detect vessel penetration. Early detection and immediate intervention are crucial to mitigate adverse outcomes. Continuous education and training for practitioners, along with advancements in filler materials and injection methods, are essential for improving the safety of cosmetic procedures. This comprehensive understanding aids in preventing and managing vascular complications, ensuring better patient outcomes. The field of dermal filler treatments is advancing with new techniques and technologies, such as High-Resolution Ultrasound, Infrared Imaging, self-crossing hyaluronic acid filler, biodegradable microspheres, and microinjection.

Safe Zones for Facial Fillers: Anatomical Study of SubSMAS Spaces in Asians.

The study "Spaces of the Face for Filler Procedures: Identification of subSMAS Spaces Based on Anatomical Study" explores the anatomy of facial spaces crucial for safe and effective filler injections. By delineating the subSMAS (sub-superficial musculoaponeurotic system) spaces, this research highlights how these virtual compartments, bordered by fat, muscles, fascia, and ligaments, facilitate independent muscle movement and reduce the risk of damaging critical structures. The thicker and more robust skin of East Asians necessitates deeper filler injections, emphasizing the significance of accurately identifying these spaces. A cadaver study with dyed gelatin validated the existence and characteristics of these subSMAS spaces, confirming their safety for filler procedures. Key spaces, such as the subgalea-frontalis, interfascial and temporalis, and prezygomatic spaces, were examined, illustrating safe zones for injections. The findings underscore the importance of anatomical knowledge for enhancing facial aesthetics while minimizing complications. This study serves as a guide for clinicians to perform precise and safe filler injections, providing a foundation for further research on the dynamic interactions of these spaces and long-term outcomes.

Sihler's staining of the anterior belly of digastric muscle for botulinum toxin injection.

PURPOSE: The anterior belly of the digastric muscle (ABDM) is the target of botulinum toxin injection; however, anatomical considerations related to the injection point are absent. This study used Sihler's staining to analyze the intramuscular nerve distribution of ABDM to identify the most effective botulinum toxin injection points. METHODS: We used 12 specimens from 6 embalmed cadavers in this study. The specimens were manually dissected to preserve the mylohyoid nerve and subjected to Sihler's staining. From the gnathion to and hyoid bone, the ABDM was divided into three equal parts, distinguishing the anterior, middle, and posterior thirds. RESULTS: Only a branch of the mylohyoid nerve entered the ABDM, and its entry point was located in the middle-third region in all cases. The nerve endings were concentrated in the middle third (100%), followed by the anterior third (58.3%) and were not observed in the posterior third. CONCLUSION: The landmarks used in this study (gnathion and hyoid bone) are easily palpable on the skin surface, allowing clinicians to target the most effective injection site (middle third of ABDM). These results provide scientific and anatomic evidence for injection points, and will aid in the management of ABDM injection procedures in clinical practice.

Sonoanatomy of injecting botulinum neurotoxin into the facial muscles.

INTRODUCTION: Ultrasonography (US) has become an essential tool for guiding botulinum neurotoxin (BoNT) injections in facial muscles, enhancing precision and safety. This narrative review explores the role of US in BoNT administration, particularly in complex anatomical regions, highlighting its impact on treatment customization, real-time visualization, and complication reduction. MATERIALS AND METHODS: A comprehensive literature search was conducted using PubMed, MEDLINE, Embase, and Cochrane Library for articles published from January 2018 to December 2023. Search terms included "Botulinum neurotoxin," "facial anatomy," "ultrasonography guided injection," and "facial muscle sonoanatomy." Studies focusing on US-guided BoNT injections in facial muscles were included. Data extraction and synthesis were performed independently by two reviewers, focusing on study design, ultrasonography techniques, outcomes, and conclusions. RESULTS: The review found that US guidance significantly enhances the precision of BoNT injections by providing real-time visualization of facial muscles and blood vessels, thereby reducing the risk of adverse events. US enables tailored injection strategies, ensuring symmetrical facial expressions and minimizing over-treatment. The technique also offers immediate feedback, allowing for on-the-spot adjustments to improve treatment efficacy and safety. However, the review identified limitations, including potential selection bias and variability in US techniques across different studies. CONCLUSION: US guidance for BoNT injections into facial muscles offers substantial benefits in terms of precision, safety, and treatment customization. Despite the identified limitations, the integration of US into clinical practice is poised to enhance patient outcomes in aesthetic and therapeutic procedures. Further research is needed to standardize US techniques and broaden the inclusivity of studies to validate these findings comprehensively.

Ultrasonographic Study of the Submandibular Gland for Botulinum Neurotoxin Injection.

BACKGROUND: Hypertrophied submandibular glands provide a bulky contour to the lower face. Botulinum neurotoxin injection methods are commonly used for facial contouring; however, no studies have suggested injection points because of the lack of delicate anatomical information on the submandibular gland. OBJECTIVE: The aim of this study was to determine the optimal injection site for botulinum neurotoxin injections in the submandibular gland. MATERIALS AND METHODS: Anatomical considerations when injecting botulinum neurotoxin into the submandibular gland were determined using ultrasonography. The thickness of the submandibular gland, its depth from the skin surface, and the location of the vascular bundle were observed bilaterally in 42 participants. Two cadavers were dissected to measure the location of the submandibular gland corresponding to the ultrasonographic observation. RESULTS: The thickest part of the submandibular gland measured 11.12 ± 2.46 in width with a depth of 4.63 ± 0.76. At the point where it crosses the line of the lateral canthus, it measured 5.53 ± 1.83 in width and 8.73 ± 1.64 in depth. CONCLUSION: The authors suggest optimal injection sites based on external anatomical landmarks. These guidelines aim to maximize the effects of botulinum neurotoxin therapy by minimizing its deleterious effects, which can be useful in clinical settings.

Self-crossing hyaluronic acid filler with combination use of polydioxanone thread in minipig model.

INTRODUCTION: The advances of self-crossing hyaluronic acid (SC-HA) fillers combination use with polydioxanone thread in minipigs were examined for compatibility, effectiveness, and immune response. MATERIALS AND METHODS: A 12-week experiment was conducted using 6 minipigs (3 male and 3 female each) to evaluate the effects of SC-HA filler. The molecular weight of SC-HA filler was fixed at 200 kDa and alternative storage modulus of G80, G250, and G500 were examined. The procedure involved injecting SC-HA filler and polydioxanone threads into the skin tissue of anesthetized minipigs, and tissue sampling after 1 month (three minipigs), and 3 months (three minipigs) for histological staining and analysis. The immune reaction was observed during the experiment. RESULTS: The practitioner reported it was easy to inject the SC-HA filler in combination with polydioxanone threads. All four storage modulus of SC-HA fillers were injectable within the polydioxanone thread containing cannula. Also, during the procedure, there were no immune responses at the treated sites. The results of the histological tissue examination confirmed that there was no chemical interaction between SC-HA filler and the existing polydioxanone thread, and it was observed that SC-HA filler was more uniformly distributed within the tissue with lower storage modulus, resulting in a higher production of collagen in the surrounding filler. When combined with scaffold polydioxanone thread, the scaffold polydioxanone thread helped spread the filler evenly, resulting in a more evenly distributed collagen around the filler. CONCLUSION: Today, the combination therapy of filler and polydioxanone thread in one procedure is challenging due to the high viscosity of conventional fillers. However, this study confirmed that combination therapy of filler and polydioxanone thread is possible with SC-HA fillers. Additionally, it was found that polydioxanone thread does not seem to interfere with the crosslinking reaction of SC-HA filler, and if used with a higher pH of polydioxanone, it may enhance the cross-linking reaction and achieve a higher viscosity value. Finally, the study resulted in the idea of concrete as SC-HA filler and reinforcing rod for polydioxanone thread.

Anatomy of the temporal region to guide filler injections.

Hollow temples are not typically considered aesthetically pleasing, and hollowness worsens with the aging process. When filling this region with fillers, there are several anatomical considerations, with injection techniques varying depending on the layer targeted. Specifically, injections between the superficial temporal fascia and the superficial layer of the deep temporal fascia are performed using a cannula, while periosteal layer injections involve the use of a needle to reach the bone before inserting fillers. Detailed anatomical insights encompass the boundaries of the temporal fossa and cautionary notes regarding blood vessels, supported by specific studies on veins and arteries in the temporal region. Complications, including vessel injuries, are discussed alongside an exploration of various injection techniques. This review provides a comprehensive exploration of anatomical considerations and the specific methodologies employed in temple augmentation with fillers.

A practical guide to botulinum neurotoxin treatment of teres major muscle in shoulder spasticity: Intramuscular neural distribution of teres major muscle in cadaver model.

BACKGROUND: Botulinum neurotoxin treatment typically focuses on the teres major muscle as a primary target for addressing shoulder spasticity. The muscle is located deep within a large muscle group and optimal injection locations have not been identified. OBJECTIVE: To identify the preferred location for administering botulinum toxin injections in the teres major muscle. METHODS: Teres major specimens were removed from 18 cadaveric models and stained with Sihler's method to reveal the neural distribution within the muscle. The muscles were systematically divided into equal lengths from origin to insertion. The neural density in each section was evaluated to determine the location that would be likely to increase effectiveness of the injection. RESULTS: The greatest density of intramuscular nerve endings was located in the middle 20% of the muscle. The tendinous portion was observed at the ends of the muscle. CONCLUSIONS: The results suggest that botulinum neurotoxin should be delivered in the middle 20% of the teres major muscle.

Does injecting small amounts of fillers prevent the development of secondary blindness?

INTRODUCTION: Inadvertent entry of filler products into the supratrochlear, supraorbital, or dorsal nasal arteries, among other branches of the ophthalmic artery, might result in an immediate and devastating loss of vision. We wanted to examine how much filler could block the ophthalmic artery. MATERIALS AND METHODS: Twenty-nine fresh cadavers were examined. We exposed the arterial supply to the opthalmic artery by dissecting the orbital area. Thereafter, 17 filler injections were introduced into the supratrochlear, supraorbital, and dorsal nasal arteries each. The amount of filler injection that completely blocked the ophthalmic artery was measured. Additionally, one of the head specimens was processed using phosphotungstic acid-based contrast enhancement micro-computed tomography to analyze each arteries to obstruct its whole ophthalmic artery. RESULTS: The supratrochlear, supraorbital, and dorsal nasal arteries had mean volumes in milliliter (mean ± standard deviation) of 0.0397 ± 0.010 mL, 0.0409 ± 0.00932 mL, and 0.0368 ± 0.00732 mL, respectively. However, the arteries did not differ significantly. CONCLUSION: Even a modest amount of filler injection can completely block the ophthalmic artery, resulting in visual loss.

Anatomical Considerations for the Injection of Botulinum Neurotoxin in Shoulder and Arm Contouring.

The utilization of botulinum neurotoxin in the field of body contouring is on the rise. Body contouring procedures typically focus on specific muscle groups such as the superior trapezius, deltoid, and lateral head of the triceps brachii. The authors propose identifying optimal injection sites for botulinum neurotoxin to achieve desired aesthetic contouring of the shoulders and arms. The authors conducted a modified Sihler's staining method on specimens of the superior trapezius, deltoid, and lateral head of the triceps brachii muscles, totaling 16, 14, and 16 specimens, respectively. The neural distribution exhibited the most extensive branching patterns within the horizontal section (between 1/5 and 2/5) and the vertical section (between 2/4 and 4/4) of the superior trapezius muscle. In the deltoid muscle, the areas between the anterior and posterior deltoid bellies, specifically within the range of the horizontal 1/3 to 2/3 lines, showed significant intramuscular arborization. Furthermore, the middle deltoid muscle displayed arborization patterns between 2/3 and the axillary line. Regarding the triceps brachii muscle, the lateral heads demonstrated arborization between 4/10 and 7/10. The authors recommend targeting these regions, where maximum arborization occurs, as the optimal and safest points for injecting botulinum toxin.

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.

Sihler's staining technique: How to and guidance for botulinum neurotoxin injection in human muscles.

The Sihler's stain is a whole-mount nerve staining technique that allows visualization of the nerve distribution and permits mapping of the entire nerve supply patterns of the organs, skeletal muscles, mucosa, skin, and other structures that contain myelinated nerve fibers. Unlike conventional approaches, this technique does not require extensive dissection or slide preparation. To date, the Sihler's stain is the best tool for demonstrating the precise intramuscular branching and distribution patterns of skeletal muscles. The intramuscular neural distribution is used as a guidance tool for the application of botulinum neurotoxin injections. In this review, we have identified and summarized the ideal botulinum neurotoxin injection points for several human tissues.

A standardized protocol for needle placement in the infraspinatus muscle: an anatomical perspective.

PURPOSE: This study aimed to evaluate the morphology of the three parts of the infraspinatus muscle based on surface landmarks for precise and effective access, and to propose the most effective fine-wire electrode insertion technique and sites. METHODS: Fifteen Asian fresh cadavers were used. We investigated the probability of the presence of the superior, middle, and inferior parts in each infraspinatus muscle based on surface landmarks. Based on the positional characteristics of the muscle, we determined the needle insertion method and confirmed its effectiveness by dissection. RESULTS: The superior part was mostly observed near the spine of the scapula. The middle part was broadly observed within the infraspinous fossa. The inferior part showed variable location within the infraspinous fossa. The injection accuracy of the superior, middle, and inferior parts in the infraspinatus muscle was 95.8%, 100%, and 91.7%, respectively. Targeting the superior and middle parts for injection of the infraspinatus muscle is relatively more straightforward than targeting the inferior part. Targeting the inferior part of the infraspinatus muscle in this study was more challenging than targeting the superior and middle parts. CONCLUSION: Needling for electromyography should be performed with special care to avoid unintended muscle parts, which could lead to inaccurate data acquisition and affect the conclusions about muscle function.

Sonoanatomy of the platysmal bands: What causes the platysmal band?

BACKGROUND: The platysmal band is created by the platysma muscle, a thin superficial muscle that covers the entire neck and the lower part of the face. The platysmal band appears at the anterior and posterior borders of the muscle. To date, no definite pathophysiology has been established. Here, we observed a lack of knowledge of the anatomy of the platysma muscle using ultrasonography in this study. METHODS: We conducted a descriptive, prospective study observing the platysmal band in resting and contraction states to reveal muscle changes. Twenty-four participants (aged 23-57 years) with anterior and posterior neck bands underwent ultrasonography in resting and contracted states. Ten cadavers were studied aged 67-85 years to measure the thickness of the platysma muscle at 12 points: horizontally (medial, middle, lateral) and vertically (inferior mandibular margin, hyoid bone, cricoid cartilage, superior margin of clavicle). RESULTS: The anterior and posterior borders of the platysma muscle were thicker than the middle of the platysma muscle when in a contracted state, and the muscle also had a convex shape when contracted. The thickness of the platysma muscle was not significantly different over 12 points in the resting state. During contraction, the platysma muscles contracted in the medial and lateral margins of the muscle, which was more significant in the posterior bands. CONCLUSION: The anterior and posterior platysmal bands are related to muscle thickness during contraction. These observations support the change in platysmal band treatment only at the anterior and posterior border of the muscle.

Intramuscular Neural Distribution of Adductor Pollicis Muscle Spasticity in Cadaver Model Regarding Botulinum Neurotoxin Treatment.

PURPOSE: The adductor pollicis muscle is frequently targeted for botulinum neurotoxin injective treatment for spasticity. However, there are no injective guidelines for delivering injection to the muscle. MATERIALS AND METHODS: A method known as the modified Sihler's method was used to stain the adductor pollicis muscle in 16 specimens to reveal intramuscular neural distribution of the muscle. RESULTS: The most intramuscular neural distribution was located on 1/5 to 3/5 of the muscle regarding midline of 3rd metacarpal bone (0) to the base of the 1st proximal phalanx (5/5). The nerve entry point was mostly located on 0 to 1/5 of the muscle. CONCLUSION: The result suggests that botulinum neurotoxin should be delivered at the middle of second metacarpal bone via deep injection.