Guideline for Botulinum Toxin Injections in the Effective Treatment of Fibular Spasticity

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.

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.

Improved Gait and Radiological Measurements After injection of Botulinum Toxin Into Peroneus Longus in Young Children With USCP and Equinovalgus Gait

BACKGROUND

Children with cerebral palsy develop foot deformities due to a combination of factors including muscle shortening, hypertonia, weakness, and cocontraction of muscles acting at the ankle joint resulting in an altered gait pattern. We hypothesized these factors affect the peroneus longus (PL) and tibialis anterior (TA) muscles couple in children who develop equinovalgus gait first followed by planovalgus foot deformities. Our aim was to evaluate the effects of abobotulinum toxin A injection to the PL muscle, in a cohort of children with unilateral spastic cerebral palsy and equinovalgus gait.

METHODS

This was a prospective cohort study. The children were examined within 12 months before and after injection to their PL muscle. Twenty-five children of mean age 3.4 (S.D.: 1.1) years were recruited.

RESULTS

We found significant improvement in foot radiology measures. Passive extensibility of the triceps surae did not change, whereas active dorsiflexion increased significantly. Nondimensional walking speed increased by 0.1 (95% confidence interval [CI], [0.07, 0.16]; P < 0.001), and the Edinburgh visual gait score improved by 2.8 (95% CI, [-4.06, -1.46]; P < 0.001). Electromyography showed increased recruitment for gastrocnemius medialis (GM) and TA but not for PL during the reference exercises (standing on tip toes for GM/PL, active dorsiflexion for TA) and decreased activation percentages for PL/GM and TA across sub-phases of gait.

CONCLUSIONS

One key advantage of treating the PL muscle only might be to address foot deformities without interfering with the main plantar flexors that are instrumental to support body weight during gait.

The highest region of muscle spindle abundance should be the optimal target of botulinum toxin A injection to block muscle spasms in rats

Purpose

The effective relief of muscle spasticity requires prompt solutions in rehabilitation medicine. This study aimed to reveal that the highest region of muscle spindle abundance is the optimal target of botulinum toxin A (BTX-A) injections for relieve muscle spasm.

Methods

Sixty adult, male Sprague-Dawley rats with lower limbs spasm caused by stroke after modeling, weighing (200 ± 20) g, were included in this study. The modelrats were divided into four groups: muscle spasm model group (group A), model rats treated with BTX-A injections into the middle of the muscle belly (group B), model rats treated with BTX-A injections into the center of the intramuscular nerve-dense region (INDR) (group C), and model rats treated with BTX-A injection into the center of the highest region of muscle spindle abundance (HRMSA) (group D). Groups B, C, and D were further divided into two subgroups: the 3rd and 6th days after BTX-A injection. The rats in each group were assigned modified Ashworth scale scores (MAS), and the changes in gastrocnemius muscle tone, wet muscle weight, and cross-sectional area of muscle fiber were detected.

Results

Muscle spindle abundance was the highest in the upper part of the INDR. Group B experienced no significant changes in MAS, muscle tone, wet muscle weight, or cross-sectional area of the muscle fiber. Conversely, groups C and D experienced a decrease in these indicators. Group C experienced the most significant decrease in wet muscle weight and cross-sectional area of muscle fibers. Group D experienced the most notable decrease in MAS and muscle tone. There were no significant differences in the indicators between the 3rd and 6th days after BTX-A injections in group B and there were significant differences in the improvement in the indicators between the two subgroups in groups C and D, with group D experiencing more notable intersubgroup differences.

Conclusion

The efficacy of BTX-A injections into the HRMSA is significantly superior to that of conventional BTX-A injections into the middle of the belly muscle or the INDR in the treatment of muscle spasms. Hence, HRMSA should be the optimal target of BTX-A to relieve muscle spasms.