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

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

A randomized double blinded placebo controlled study to evaluate motor unit abnormalities after experimentally induced sensitization using capsaicin

Central sensitization is a condition that represents a cascade of neurological adaptations, resulting in an amplification of nociceptive responses from noxious and non-noxious stimuli. However, whether this abnormality translates into motor output and more specifically, ventral horn abnormalities, needs to be further explored. Twenty healthy participants aged 20-70 were randomly allocated to topical capsaicin or a placebo topical cream which was applied onto their left upper back to induce a transient state of sensitization. Visual analogue scale (VAS) ratings of pain intensity and brush allodynia score (BAS) were used to determine the presence of pain and secondary allodynia. Surface electromyography (sEMG) and intramuscular electromyography (iEMG) were used to record motor unit activity from the upper trapezius and infraspinatus muscles before and twenty minutes after application of capsaicin/placebo. Motor unit recruitment and variability were analyzed in the sEMG and iEMG, respectively. An independent t-test and Kruskal-Wallis H test were performed on the data. The sEMG results demonstrated a shift in the motor unit recruitment pattern in the upper trapezius muscle, while the iEMG showed a change in motor unit variability after application of capsaicin. These results suggest that capsaicin-induced central sensitization may cause changes in ventral horn excitability outside of the targeted spinal cord segment, affecting efferent pathway outputs. This preclinical evidence may provide some explanation for the influence of central sensitization on changes in movement patterns that occur in patients who have pain encouraging of further clinical investigation.Clinical Trials registration number: NCT04361149; date of registration: 24-Apr-2020.

Efficacy and Safety of Botulinum Toxin Type A Injection in Patients with Bilateral Trapezius Hypertrophy

OBJECTIVE

To evaluate aesthetic outcomes in patients with bilateral trapezius hypertrophy treated by botulinum toxin type A (BTxA) injection for aesthetic reconstruction of the upper trapezius.

METHODS

From May 2015 to May 2016, 30 women with a short neck shape resulting from bilateral trapezius hypertrophy were treated with botulinum toxin type A (BTxA) injection at the most affected area of the upper trapezius. Pre- and postoperative values of SACDF (irregularly shaped area of the four points A, C, D, and F) and SACDE (irregularly shaped area of the four points A, C, D, and E), responses to patients' and doctors' Global Aesthetic Improvement Scale (GAIS) questionnaires for neck aesthetic assessment, as well as reported adverse events, were recorded and analyzed.

RESULTS

Duration of follow-up ranged from 4 to 12 months. Subjects experienced non-severe adverse events and complete recovery after a single BTxA injection. In patients' GAIS questionnaires, "very much improved" accounted for 53%, "much improved" accounted for 13%, and "improved" accounted for 27%. In doctors' GAIS questionnaires, "very much improved" accounted for 27%, "much improved" accounted for 33%, "improved" accounted for 33%, and "no change" accounted for 7%. The overall degree of improvement was high. Statistically significant differences were observed with respect to the "very much improved" response to GAIS questionnaires between patients and doctors (P = 0.035).

CONCLUSION

A single injection of BTxA for aesthetic reconstruction of the upper trapezius is safe and effective in patients with bilateral trapezius hypertrophy.

LEVEL OF EVIDENCE IV

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

[Microinjection of endomorphin-1 in the ventrolateral periaqueductal gray induces descending inhibition of cardiac nociception by activating μ-opioid receptor in rats]

OBJECTIVE

To observe descending inhibition of cardiac nociception induced by microinjection of endomorphin-1 (EM1) in the ventrolateral periaqueductal gray (VLPAG) in rats effect and explore the role of μ-opioid receptor in mediating this effect.

METHODS

Male SD rats were randomized into electromyography (EMG) group and c-Fos group, both of which were further divided into 5 subgroups, namely 0.9% NaCl group, bradykinin (BK) group, BK+EM1 group, BK+CTOP group, and BK+CTOP+EM1 group. Rat models of cardiac nociception were established by intrapericardial injection of BK. The changes of cardiaosomatic motor reflex induced by BK were observed by assessing EMG responses of the dorsal spinotrapezius muscle; c-Fos expression in the spinal dorsal horn at levels T₃-T₅ was tested.

RESULTS

Compared with 0.9% NaCl, intrapericardial BK injection induced obvious EMG activities and significantly increased c-Fos expression in the spinal dorsal horn at T₃-T₅ (P < 0.05). Compared with BK injection, microinjection of EM1 in the VLPAG dose-dependently inhibited EMG activities and significantly decreased c-Fos expression (P < 0.05); microinjection of CTOP in the VLPAG produced no significant effect on EMG or c-Fos expression (P > 0.05). Microinjection of CTOP obviously reversed EM1-induced inhibition of EMG activities and c-Fos expression (P < 0.05).

CONCLUSIONS

Microinjection of EM1 in the VLPAG produces descending inhibition of cardiac nociception in rats by activating μ-opioid receptor.

Comparison of the Efficiency of Ultrasound-Guided Injections of the Rhomboid Major and Trapezius Muscles in Myofascial Pain Syndrome: A Prospective Randomized Controlled Double-blind Study

OBJECTIVES

We aimed to investigate the effect of ultrasound (US)-guided injections of the rhomboid major (deep) and trapezius (superficial) muscles on pain, disability, and quality of life in patients with myofascial pain syndrome.

METHODS

In this prospective randomized controlled double-blind study, 65 patients with a diagnosis of myofascial pain syndrome were randomized into 2 groups. In group 1 (n = 33), US-guided rhomboid major muscle injection was performed, and in group 2 (n = 32), US-guided trapezius muscle injection was performed. The patients were assessed by a visual analog scale for pain, the Pressure Pain Threshold, the Neck Pain and Disability Scale, and Short Form 12. Data were obtained before treatment (week 0), the second week after treatment, and the fourth week after treatment.

RESULTS

In both groups, significant improvements were observed for all parameters at both weeks 2 and 4 compared to pretreatment values (P < .05). A comparison of the groups showed significantly superior results in group 1 for all parameters at week 2 (P < .05) and for all parameters but the Physical Component Scale of Short Form 12 at week 4 (P < .05).

CONCLUSIONS

We think that US-guided deep injection of the rhomboid major muscle was more effective than superficial injection of the trapezius muscle for pain, disability, and quality of life in patients with myofascial pain syndrome.

Intrarticular injections of hyaluronic acid for trapezio-metacarpal osteoarthritis: a systematic review

Osteoarthritis (OA) of the base of the thumb, also known as Trapezio-Metacarpal (TM) OA, is a disabling condition, which mainly affects women and manual workers. When TM OA is not adequately treated, patients develop deformity and loss of function of the thumb. The surgical approach is a widespread strategy to treat this condition, but there is still no consensus on the most effective procedure. Therefore, several conservative strategies are commonly used, such as nonsteroidal anti-inflammatory drugs (NSAIDs) administration, thumb strengthening exercise, splinting, steroid (CS) and hyaluronic acid (HA) intrarticular injections. The present review of the literature aims to summarize the available scientific evidence on the treatment of TM OA with injections of HA. Thirteen studies were included: 7 randomized controlled trials, 5 case series and a case-control study. Among these, 5 studies compared HA versus CS injection. Results from most of them reported better outcomes with HA injections in terms of function (strength) and joint motion, while CS injections had greater effect on pain; moreover, CS action was faster but shorter, while HA required more time to obtain a therapeutic benefit and lasted longer. In non-comparative articles, this trend was also confirmed. Indeed, the authors reported an improvement in pain relief up to six months. Similarly, all studies indicated hand function improvement over time, measured though DASH score, pincher and grip strength tests. Available data from included studies show that there is no clear evidence to suggest a treatment with HA injections as the best advisable non-operative treatment for TM OA. However, promising potentials were shown by the randomized controlled trials, suggesting that there is some benefit and less comorbidities with the administration of HA. Further research, such as trials evaluating larger cohorts with validated scores for long-term follow-up, is still necessary.

Protein Supplementation Does Not Further Increase Latissimus Dorsi Muscle Fiber Hypertrophy after Eight Weeks of Resistance Training in Novice Subjects, but Partially Counteracts the Fast-to-Slow Muscle Fiber Transition

The response to resistance training and protein supplementation in the latissimus dorsi muscle (LDM) has never been investigated. We investigated the effects of resistance training (RT) and protein supplementation on muscle mass, strength, and fiber characteristics of the LDM. Eighteen healthy young subjects were randomly assigned to a progressive eight-week RT program with a normal protein diet (NP) or high protein diet (HP) (NP 0.85 vs. HP 1.8 g of protein·kg⁻¹·day⁻¹). One repetition maximum tests, magnetic resonance imaging for cross-sectional muscle area (CSA), body composition, and single muscle fibers mechanical and phenotype characteristics were measured. RT induced a significant gain in strength (+17%, p < 0.0001), whole muscle CSA (p = 0.024), and single muscle fibers CSA (p < 0.05) of LDM in all subjects. Fiber isometric force increased in proportion to CSA (+22%, p < 0.005) and thus no change in specific tension occurred. A significant transition from 2X to 2A myosin expression was induced by training. The protein supplementation showed no significant effects on all measured outcomes except for a smaller reduction of 2X myosin expression. Our results suggest that in LDM protein supplementation does not further enhance RT-induced muscle fiber hypertrophy nor influence mechanic muscle fiber characteristics but partially counteracts the fast-to-slow fiber shift.

RETRACTED: Pectoral nerves block for a contraction of the latissimus dorsi muscle

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editor-in-Chief as it contains fabricated/falsified data. The Editor-in-Chief decision was based on the investigation by the Japanese Society of Anesthesiologists which concluded that no research was conducted and all the data including patient backgrounds were fabricated. The society also concluded that the corresponding author, Dr. Ueshima presented the names of the individuals not involved or only partially involved in research as lead authors, presented the names of the individuals not involved in research as co-authors and submitted papers without the agreement of the co-authors. The investigation report can be found here https://anesth.or.jp/img/upload/ckeditor/files/2105_34_700_2.pdf.

Injections of Local Anesthetics into the Pharyngeal Region Reduce Trapezius Muscle Tenderness

BACKGROUND

Neck pain is a frequent reason for seeking medical advice. Neuroanatomical findings suggest a close connection between the pharynx and the trapezius region. Irritation of the pharynx may induce tenderness of this area. Specific tender points, called neck reflex points (NRPs), can be identified here with high reproducibility. We hypothesized that therapeutic local anesthesia (TLA; or neural therapy, NT) in the pharyngeal region can reduce tenderness in patients with therapy-resistant neck pain.

PATIENTS AND METHODS

17 consecutive female patients with chronic cervical pain and positive trapezius NRPs received bilateral injections of 0.5 ml 1% procaine into the palatine velum. The NRPs were assessed using a 3-level pain index (PI = 0, 1, or 2) before and 3-5 min after each injection.

RESULTS

We found a significant reduction in tenderness of the NRP of the trapezius region (NRP C7) immediately after TLA/NT. 30 positive NRPs were found before therapy and only 13 after therapy (p < 0.01). The average PI of the NRP C7 was 1.24 ± 0.77 before and 0.35 ± 0.59 after therapy (right side), and 1.34 ± 0.59 before and 0.59 ± 0.69 after therapy (left side). The pre- and post-therapy PI values were significantly different on both the right and left sides of the trapezius region (p < 0.01). No adverse effects were observed.

CONCLUSIONS

Pharyngeal irritation may induce and maintain therapy-resistant cervical pain in patients with chronic pharyngeal disease. These patients could benefit from remote TLA/NT injections in the pharyngeal region.

Monitoring recovery from rocuronium-induced neuromuscular block using acceleromyography at the trapezius versus the adductor pollicis muscle: an observational trial

PURPOSE

Positioning for surgery can restrict access to the patient's hand, thereby limiting assessment of the response at the adductor pollicis muscle to ulnar nerve stimulation. We evaluated a novel site to assess neuromuscular block by stimulating the accessory nerve and measuring the acceleromyographic response at the trapezius muscle.

METHODS

In this prospective non-blinded observational study, we assessed neuromuscular transmission in anesthetized adult female patients undergoing elective laparoscopic gynecological surgery. We performed the assessment by simultaneous recording acceleromyographic responses with the TOF-Watch(®) SX monitor at both the right adductor pollicis and left trapezius muscles. The neuromuscular block was achieved using rocuronium 0.3 mg·kg(-1), and the repeatability, time course, and limits of agreement (Bland-Altman) of responses were compared at the two recording sites. The primary endpoint was the 90% train-of-four (TOF) recovery time with other endpoints included the onset time of the block, maximum T1 depression, time to 25% T1 recovery, and recovery time course of the T1 response and TOF ratio.

RESULTS

Thirty-six patients were enrolled with responses obtained from 27 subjects. The variability of baseline responses recorded at the trapezius muscle was larger than that recorded at the adductor pollicis muscle, as determined by their mean (SD) repeatability coefficients [twitch height T1, 6.1 (1.9)% and 4.2 (1.6)%, respectively; P = 0.001; TOF ratio, 6.2 (2.1)% and 4.3 (1.7)%, respectively; P = 0.001]. The recorded responses showed relatively narrow limits of agreement. The onset time of the block was 0.3 min earlier at the trapezius muscle than at the adductor pollicis muscle [2.3 (0.8) min and 2.6 (0.7) min, respectively; P = 0.007], with limits of agreement ranging from 1.6 min earlier to 1.0 min later. The time to 25% T1 recovery was 1.8 min earlier at the trapezius muscle than at the adductor pollicis muscle [18.2 (5.7) min and 20.0 (5.2) min, respectively; P = 0.039], with limits of agreement ranging from 11.1 min earlier to 7.5 min later. Additionally, the time to achieve 90% TOF ratio was 4.4 min earlier at the trapezius muscle than at the adductor pollicis muscle [32.6 (7.9) min and 37 (9.1) min, respectively; P = 0.004], with limits of agreement ranging from 18.4 min earlier to 9.7 min later.

CONCLUSIONS

We conclude that recording evoked acceleromyographic responses at the trapezius muscle is an acceptable alternative when monitoring from the adductor pollicis muscle is compromised. Nevertheless, we caution that recording a 90% TOF response at the trapezius muscle may overestimate functional recovery from the neuromuscular blockade. This trial was registered at ClinicalTrials.gov identifier, NCT01849198.

Lidocaine Injection in the Intramuscular Innervation Zone Can Effectively Treat Chronic Neck Pain Caused by MTrPs in the Trapezius Muscle

BACKGROUND

An increasing number of people suffer from neck pain due to life style and prolonged use of computers. Research has revealed that myofascial trigger points (MTrPs) and the intramuscular innervation zone (IZ) are involved in neck pain. MTrPs are induced mainly by IZ dysfunction of the affected skeletal muscle and the 2 do not overlap in location. The question is whether injection treatment in MTrPs or in the IZ is more effective to relieve MTrPs-associated pains. The precise location and body-surface map of the intramuscular IZ in the trapezius muscle and a clinical injection study in the IZ may provide a useful answer to the question.

OBJECTIVES

This study aimed to investigate the efficacy of lidocaine injection in the intramuscular IZ for the treatment of chronic neck pain caused by MTrPs in the trapezius muscle.

STUDY DESIGN

Prospective observational study, approved by the local research ethics.

SETTING

University hospital, departments of Anesthesiology and Anatomy.

METHODS

First, for the determination of IZ distribution and body-surface mapping, a modified intramuscular Sihler's neural staining technique was applied to elucidate nerve distribution patterns of the trapezius muscle. Then, 120 patients with myofascial pain syndrome (MPS) of the trapezius muscle were randomly divided into 5 groups for analysis. Group 1 (n = 24) received injections of saline (0.9% NaCl) at the MTrPs. Group 2 (n = 24) received injections of 0.5% lidocaine at the MTrPs. Group 3 (n = 24) received injections of saline (0.9% NaCl) at the mid-upper trapezius (Point E). Group 4 (n = 24) received injections of 0.5% lidocaine at Point E. Group 5 (n = 24) received a combined injection of 0.5% lidocaine treatment at both Point E and the lower trapezius (Point F). The injection dose was 4 mL at each injection site. All patients received injections once a week for 4 weeks. The visual analogue scale (VAS) and the frequency of painful days per month (FPD) were obtained before treatment and at 2, 4, and 6 months after treatment.

RESULTS

The intramuscular terminal nerve branches presented a "dendritic" distribution in the trapezius muscle and were connected with each other to form an S-shaped IZ belt in the middle of the muscle belly. Compared with the MTrP injection group, lidocaine-injection therapy in the IZ significantly reduced the degree and frequency of neck pain in patients at 6 months after treatment, especially the combined lidocaine-injection therapy in the IZ of both the mid-upper trapezius and the lower trapezius are more effective (all P < 0.05).

CONCLUSIONS

This study confirms that lidocaine-injection therapy in the IZ significantly reduces the degree and frequency of neck pain in patients at 6 months after treatment. The combined lidocaine-injection therapy in the IZ of both the mid-upper trapezius and the lower trapezius is more effective. In addition, this study establishes a clear distribution map of intramuscular nerves that will be conducive to the future use of chemical blockers and electrical stimulation in the nervous system in treating MPS of the trapezius muscle.

LIMITATIONS

The small number of patients and the short duration of follow-up.

Effect of lidocaine patches on upper trapezius EMG activity and pain intensity in patients with myofascial trigger points: A randomized clinical study

OBJECTIVE

To compare the effects of 5% lidocaine patches and placebo patches on pain intensity and electromyographic (EMG) activity of an active myofascial trigger point (MTrP) of the upper trapezius muscle.

MATERIALS AND METHODS

Thirty-six patients with a MTrP in the upper trapezius muscle were randomly divided into two groups: 20 patients received lidocaine patches (lidocaine group) and 16 patients received placebo patches (placebo group). They used the patches for 12 h each day, for 2 weeks. The patch was applied to the skin over the upper trapezius MTrP. Spontaneous pain, pressure pain thresholds, pain provoked by a 4-kg pressure applied to the MTrP and trapezius EMG activity were measured before and after treatment.

RESULTS

Baseline spontaneous pain values were similar in both groups and significantly lower in the lidocaine group than the placebo group after treatment. The baseline pressure pain threshold was significantly lower in the lidocaine group, but after treatment it was significantly higher in this group. Baseline and final values of the pain provoked by a 4-kg pressure showed no significant difference between the groups. Baseline EMG activity at rest and during swallowing of saliva was significantly higher in the lidocaine group, but no significant difference was observed after treatment. Baseline EMG activity during maximum voluntary clenching was similar in both groups, but significantly higher in the lidocaine group after treatment.

CONCLUSIONS

These clinical and EMG results support the use of 5% lidocaine patches for treating patients with MTrP of the upper trapezius muscle.