Localization of the center of the intramuscular nerve dense region of the medial femoral muscles and the significance for blocking spasticity

Division of neuromuscular compartments and localization of the center of the highest region of muscle spindles abundance in deep cervical muscles based on Sihler's staining

Purpose

The overall distribution pattern of intramuscular nerves and the regions with the highest spindle abundance in deep cervical muscles have not been revealed. This study aimed to reveal neuromuscular compartmentalization and localize the body surface position and depth of the center of the region of highest muscle spindle abundance (CRHMSA) in the deep cervical muscles.

Methods

This study included 36 adult cadavers (57.7 ± 11.5 years). The curved line joining the lowest point of the jugular notch and chin tip was designated as the longitudinal reference line (line L), and the curved line connecting the lowest point of the jugular notch and acromion was designated as the horizontal reference line (line H). Modified Sihler's staining, hematoxylin-eosin staining and computed tomography scanning were employed to determine the projection points (P) of the CRHMSAs on the anterior surfaces of the neck. The positions (PH and PL) of point P projected onto the H and L lines, and the depth of each CRHMSA, and puncture angle were determined using the Syngo system.

Results

The scalenus posterior and longus capitis muscles were divided into two neuromuscular compartments, while the scalenus anterior and longus colli muscles were divided into three neuromuscular compartments. The scalenus medius muscle can be divided into five neuromuscular compartments. The PH of the CRHMSA of the scalenus muscles (anterior, medius, and posterior), and longus capitis and longus colli muscles, were located at 36.27, 39.18, 47.31, 35.67, and 42.71% of the H line, respectively. The PL positions were at 26.53, 32.65, 32.73, 68.32, and 51.15% of the L line, respectively. The depths of the CRHMSAs were 2.47 cm, 2.96 cm, 2.99 cm, 3.93 cm, and 3.17 cm, respectively, and the puncture angles were 87.13°, 85.92°, 88.21°, 58.08°, and 77.75°, respectively.

Conclusion

Present research suggests that the deep cervical muscles can be divided into neuromuscular compartments; we recommend the locations of these CRHMSA as the optimal target for administering botulinum toxin A injections to treat deep cervical muscle dystonia.

Localisation of the centre of the highest region of muscle spindle abundance of anterior forearm muscles

The centre of the highest region of muscle spindle abundance (CHRMSA) in the intramuscular nerve-dense region has been suggested as the optimal target location for injecting botulinum toxin A to block muscle spasms. The anterior forearm muscles have a high incidence of spasticity. However, the CHRMSA in the intramuscular nerve-dense region of the forearm anterior muscle group has not been defined. This study aimed to accurately define the body surface position and the depth of CHRMSA in an intramuscular nerve-dense region of the anterior forearm muscles. Twenty-four adult cadavers (57.7 ± 11.5 years) were included in this study. The curved line close to the skin connecting the medial and lateral epicondyles of the humerus was designated as the horizontal reference line (H line), and the line connecting the medial epicondyle of the humerus and the ulnar styloid was defined as the longitudinal reference line (L line). Modified Sihler's staining, haematoxylin-eosin staining and computed tomography scanning were employed to determine the projection points (P and P') of the CHRMSAs on the anterior and posterior surfaces of the forearm. The positions (PH and PL) of point P projected onto the H and L lines, and the depth of each CHRMSA, were determined using the Syngo system. The PH of the CHRMSA of the ulnar head of pronator teres, humeral head of pronator teres, flexor carpi radialis, palmaris longus, flexor carpi ulnaris, ulnar part of flexor digitorum superficialis, radial part of flexor digitorum superficialis, flexor pollicis longus, ulnar part of flexor digitorum profundus, radial portion of flexor digitorum profundus and pronator quadratus muscles were located at 42.48%, 45.52%, 41.20%, 19.70%, 7.77%, 25.65%, 47.42%, 53.47%, 12.28%, 38.41% and 51.68% of the H line, respectively; the PL were located at 18.38%, 12.54%, 28.83%, 13.43%, 17.65%, 32.76%, 57.32%, 64.12%, 20.05%, 45.94% and 88.71% of the L line, respectively; the puncture depths were located at 21.92%, 27.25%, 23.76%, 18.04%, 15.49%, 31.36%, 26.59%, 41.28%, 38.72%, 45.14% and 53.58% of the PP' line, respectively. The percentage values are the means of individual values. We recommend that the body surface puncture position and depth of the CHRMSA are the preferred locations for the intramuscular injection of botulinum toxin A to block anterior forearm muscle spasms.

Division of neuromuscular compartments and localization of the center of the intramuscular nerve-dense region in pelvic wall muscles based on Sihler's staining

The innervation of the pelvic wall muscles is not very clear. This study aimed to reveal the division of neuromuscular compartments and localize the surface position and depth of the center of the intramuscular nerve-dense region (CINDR) of the pelvic wall muscles based on Sihler's staining. Twenty-four adult cadavers were used. To localize the CINDR of the pelvic wall muscles, horizontal (H) and longitudinal (L) reference lines were drawn, and Sihler's staining was used to reveal the intramuscular nerve distribution. The CINDR projection points (P and P' points) behind and in front of the body surface, the positions of the P points projected onto the H and L lines (PH and PL points), and the depth of CINDR were determined by spiral computed tomography scanning. The piriformis and obturator internus muscles can be divided into two and three neuromuscular compartments, respectively. The PH of CINDR of the piriformis muscle was located at 22.61 ± 2.66% of the H line, the PL was at 28.53 ± 6.08% of the L line, and the puncture depth of the piriformis muscle was at 24.64 ± 2.16% of the PP' line. The PH of CINDR of the obturator internus muscle was at 16.49 ± 1.20% of the H line, the PL was at 10.94 ± 1.09% of its L line, and the puncture depth was 6.26 ± 0.38 cm. These findings may guide the design of the compartmentalized transplantation of the pelvic wall muscles and improve the target localization efficiency and efficacy for injecting botulinum toxin A to treat pelvic wall muscle spasm.

Three-dimensional mapping reveals heterochronic development of the neuromuscular system in postnatal mouse skeletal muscles

The development of the neuromuscular system, including muscle growth and intramuscular neural development, in addition to central nervous system maturation, determines motor ability improvement. Motor development occurs asynchronously from cephalic to caudal. However, whether the structural development of different muscles is heterochronic is unclear. Here, based on the characteristics of motor behavior in postnatal mice, we examined the 3D structural features of the neuromuscular system in different muscles by combining tissue clearing with optical imaging techniques. Quantitative analyses of the structural data and related mRNA expression revealed that there was continued myofiber hyperplasia of the forelimb and hindlimb muscles until around postnatal day 3 (P3) and P6, respectively, as well as continued axonal arborization and neuromuscular junction formation until around P3 and P9, respectively; feature alterations of the cervical muscle ended at birth. Such structural heterochrony of muscles in different body parts corresponds to their motor function. Structural data on the neuromuscular system of neonatal muscles provide a 3D perspective in the understanding of the structural status during motor development.

The Pedicled Flap of Adductor Longus, a New Technique for Inguinal Reconstruction

Introduction: Reconstruction surgeries of the inguinal area pose a challenge for oncological and orthopedic surgeons, especially after radical local resection (RLR), radical inguinal lymph node dissection (RILND), or both. Although numerous surgical procedures have been reported, there is no report about a pedicle adductor longus flap method. The aim of this work is to show our experience about inguinal reconstruction with pedicled adductor longus flap and associated outcomes. Patients and Methods: A retrospective study of 16 patients with localized inguinal region interventions and reconstructed by adductor longus flap from March 2016 to July 2020. Patients' average age was 60.0 years (range = 38-79 years) and had postoperative follow-up of 10 months (ranging 2-19 months). All patients had unilateral inguinal region involvement-seven cases on the left and nine cases on the right. The patients' clinical course, operative course, and postoperative follow-up data were evaluated. Results: All 16 patients recovered well post-operatively and did not require any re-intervention. Four patients experienced negligible discomfort around the groin area. Five patients experienced a minor strength deficit in thigh adduction compared with that of preoperative strength in the same or contralateral leg. The aforementioned complications resolved during the postoperative course and had no functional impact on their activity of daily living. All adductor longus flaps survived, completely filled the inguinal dead space, and wounds healed uneventfully within 3 weeks except for three patients who suffered delayed wound healing for more than 4 weeks. Other common complications such as infection, seroma, or wound dehiscence were not encountered in this series. Conclusion: The adductor longus flap is a reliable alternative method for inguinal region reconstruction following radical local resection (RLR), radical inguinal lymph node dissection (RILND), or both.

Localization of nerve entry points and the center of intramuscular nerve-dense regions in the adult pectoralis major and pectoralis minor and its significance in blocking muscle spasticity

The aims of this study were to localize the body surface position and depth of nerve entry points, and the center of the intramuscular nerve-dense regions of the pectoralis major and pectoralis minor in order to provide guidance for blocking muscle spasticity. Formalin-fixed adult cadavers (66.3 ± 5.2 years) were used. The curved line on the skin from the acromion to the most inferior point of the jugular notch was defined as the horizontal reference line (H). The line from the most inferior point of the jugular notch to the xiphisternal joint was defined as the longitudinal reference line (L). The nerve entry points was anatomically exposed. Sihler's staining, barium sulfate labeling, and computed tomography were employed to determine the projection points (P) on the body surface. The intersection of the longitudinal line through the P point and the H line and the horizontal line through the P point and the L line were recorded as P_H and P_L , respectively. The projection of the nerve entry points or the center of the intramuscular nerve-dense regions were in the opposite direction across the transverse plane and were recorded as P'. The percentage positions of P_H and P_L on the H and L lines, as well as the nerve entry points and the center of the intramuscular nerve-dense regions depths, were determined using the Syngo system. The pectoralis major had two nerve entry points, while the pectoralis minor had only one. In addition, two intramuscular nerve-dense regions were found in the pectoralis major, while only one region was found in the pectoralis minor. The P_H of the nerve entry points were located at 47.83%, 32.31%, and 34.31%, while the P_H of the center of the intramuscular nerve-dense regions were at 41.95%, 55.88%, and 32.58% of line H, respectively. The P_L of the nerve entry points were at -9.84%, 36.16%, and 2.44%, while the P_L for each of three center of the intramuscular nerve-dense regions was at -3.87%, 25.29%, and -7.13% of line L, respectively. The depth for each of the nerve entry points was at 17.76%, 17.53%, and 25.51% of line P-P'', respectively, and the depth of the center of the intramuscular nerve-dense regions was at 5.23%, 6.75%, and 13.73% of line P-P', respectively. These percentage values are all means. The definition of the surface position and depth of these nerve entry points and center of the intramuscular nerve-dense regions can improve the localization efficiency and efficacy of target blocking for pectoralis major and minor spasticity.

Morphologic classification and innervation patterns of the pectineus muscle

The purpose of this study was to identify the frequency of pectineal hiatus and of pectineus innervations, including femoral, obturator, and/or accessory obturator nerves. Also, this study sought to detailed intramuscular nervous distributions, with a particular focus on the relationship of nerves in multi-innervated pectineus. One hundred (49 right and 51 left) thighs from 52 cadavers (25 men and 27 women) were dissected. The morphology and innervations of the pectineus were investigated. Modified Sihler's whole-mount nerve-staining method was employed for visualization of the intramuscular nerve-distribution patterns of the pectineus. Variation of the pectineus forming a hiatus was identified in 18% of the specimens. The femoral innervations to the pectineus were identified in all specimens. Additional innervation either by the obturator or the accessory obturator branch to the pectineus was identified in 10% or 2% of specimens, respectively. No case of triple innervation to the pectineus was observed. In cases of dually innervated pectineus, two nerves formed a communication system inside the muscle. Among the three nerves supplying the pectineus, the femoral nerve branched more than the other two nerves and covered the greatest area in the muscle. The pectineal hiatus appears to be a common variation. The femoral nerve branch in a dually innervated pectineus is the dominant nerve component that supplies the muscle when considering frequency, branching pattern, and area, even though cooperation between two nerve components is implied. This study serves to advance the existing anatomical knowledge about the pectineus muscle, which is of clinical value.

Improving Botulinum Toxin Efficiency in Treating Post-Stroke Spasticity Using 3D Innervation Zone Imaging

Spasticity is a common post-stroke syndrome that imposes significant adverse impacts on patients and caregivers. This study aims to improve the efficiency of botulinum toxin (BoNT) in managing spasticity, by utilizing a three-dimensional innervation zone imaging (3DIZI) technique based on high-density surface electromyography (HD-sEMG) recordings. Stroke subjects were randomly assigned to two groups: the control group ([Formula: see text]) which received standard ultrasound-guided injections, and the experimental group ([Formula: see text]) which received 3DIZI-guided injections. The amount of BoNT given was consistent for all subjects. The Modified Ashworth Scale (MAS), compound muscle action potential (CMAP) and muscle activation volume (MAV) from bilateral biceps brachii muscles were obtained at the baseline, 3 weeks, and 3 months after injection. Intra-group and inter-group comparisons of MAS, CMAP amplitude and MAV were performed. An overall improvement in MAS of spastic elbow flexors was observed during the 3-week visit ([Formula: see text]), yet no statistically significant difference found with intra-group or inter-group analysis. Compared to the baseline, a significant reduction of CMAP amplitude and MAV were observed in the spastic biceps muscles of both groups at 3-week post-injection, and returned to approximate baseline value at 12-week post injection. A significantly higher reduction was found in CMAP amplitude ([Formula: see text]% versus [Formula: see text]%, [Formula: see text]) and MAV ([Formula: see text]% versus [Formula: see text]%, [Formula: see text]) in the experimental group compared to the control group. The study has demonstrated preliminary evidence that precisely directing BoNT to the innervation zones (IZs) localized by 3DIZI leads to a significantly higher treatment efficiency improvement in spasticity management. Results have also shown the feasibility of developing a personalized BoNT injection technique for the optimization of clinical treatment for post-stroke spasticity using proposed 3DIZI technique.