Morphometric study of the shoulder and subclavicular innervation by the intermediate and lateral branches of supraclavicular nerves

Safe zone of supraclavicular nerve during clavicle fixation and its anatomical variations, a cadaveric study

BACKGROUND

Supraclavicular nerve injury is usually at risk during clavicular fracture fixation. This study aimed to examine the anatomical features and estimate the precise location of supraclavicular nerve branches related to adjacent structural landmarks and to evaluate the differences between sex and side. To highlight the clinical purposes and surgical relevance, this study attempted to define a surgical safe zone that would probably protect the supraclavicular nerve during clavicle fixation.

METHOD

A total of 64 shoulders obtained from 15 female and 17 male adult cadavers were examined, identifying the branching patterns of the supraclavicular nerve, measuring the clavicle length and the course of the supraclavicular nerve referring to the sternoclavicular (SC) and acromioclavicular (AC) joint. Data were categorized by sex and side, and their differences were evaluated using Student T-Test and Mann-Whitney U Test. Clinically relevant predictable safe zones were also statistically analyzed.

RESULT

The results revealed 7 branching patterns of the supraclavicular nerve. The medial and lateral nerve branches formed a shared trunk, and the medial nerve branches separated to form the intermediate branch, i.e., the most frequent pattern (67.19%). The safe zones were determined to be 6.1 mm among both sexes of the SC joint medially, and 0.7 mm among females and 0 mm among males of the AC joint laterally. Surgical incisions between 29.3 to 51.2% and 60.5 to 79.7% of the clavicle length from the SC joint were the safe zones at the midclavicular shaft among both sexes.

CONCLUSION

The findings of this study have provided new insights into the anatomy of the supraclavicular nerve and its variations. It has been revealed that the terminal branches of the nerve consistently pass over the clavicle in a predictable pattern, emphasizing the importance of considering the supraclavicular nerve's safe zones during clinically relevant surgeries. Nevertheless, due to individual anatomical variations, meticulous dissection between these safe zones is necessary to avoid iatrogenic nerve injury among patients.

LEVEL OF EVIDENCE

Basic Science Study, Anatomic Study.

Regional Anesthesia for Vascular Surgery and Pain Management

Patients undergoing vascular surgery tend to have significant systemic comorbidities. Vascular surgery itself is also associated with greater cardiac morbidity and overall mortality than other types of noncardiac surgery. Regional anesthesia is amenable as the primary anesthetic technique for vascular surgery or as an adjunct to general anesthesia. When used as the primary anesthetic, regional anesthesia techniques avoid complications associated with general anesthesia in this challenging patient population. In this article, the authors describe regional anesthetic techniques for carotid endarterectomy, arteriovenous fistula creation, lower extremity bypass surgery, and amputation.

Understanding fascial anatomy and interfascial communication: implications in regional anesthesia

With the extensive application of ultrasound in regional anesthesia, there has been rapid development of interfascial plane block techniques recently. Compared with neuraxial anesthesia or nerve plexus blocks, the interfascial plane blocks have many advantages, such as technical simplicity, fewer complications and comparable or better analgesia. The concept of fascial interconnectivity is fundamental in understanding the effects and complications of interfascial plane blocks. Many fascial planes are continuous and communicate with each other without a clear anatomical boundary. The prevertebral fascia of the neck, endothoracic fascia of the chest, transversalis fascia of the abdomen, and the fascia iliaca of the pelvic cavity form a natural fascial continuation. This anatomical feature suggests that the space beneath the cervical prevertebral fascia, the thoracic paravertebral space, the space between transversalis fascia and psoas muscles (psoas major and quadratus lumborum), and the fascia iliaca compartment are a confluent potential cavity. Additionally, the permeability of the fascia at different anatomical locations to local anesthetics is different, which can also influence the block effect and the incidence of complications. This article summarizes the anatomical characteristics and communication relationships of the major fascia which are related to regional anesthesia, and their relationships with block effects and complications.

Case Report and Preliminary Exploration: Protection of Supraclavicular Nerve Branches during Internal Fixation of Clavicular Fractures through Preoperative Ultrasound Localization

Introduction

Protecting the supraclavicular nerve during internal fixation of clavicular fractures can reduce numbness in its innervation area after surgery. Previous methods for supraclavicular nerve protection are empirical, time-consuming, and approximate. In this report, we verified the feasibility of using ultrasound for percutaneous localization of the terminal branches of the supraclavicular nerve and the feasibility of an ultrasound-guided skin flap reserve technique for nerve protection.

Case Presentations

A high-frequency linear array probe was used in three cases to trace the supraclavicular nerve from its origin at the superficial cervical plexus on the surface of the clavicle. In the first case, the feasibility of percutaneous ultrasound localization of the terminal branches of the supraclavicular nerve was determined by performing an ultrasound-guided nerve block. In the second case, the feasibility of this method was determined by directly isolating this nerve under direct vision. In the third case, after the ultrasound localization, the nerves were protected by intraoperative skin retention. In the first case, skin anesthesia of the innervation area of the intermediate branch of the supraclavicular nerve was achieved. In the second case, the part of the nerve that crosses the surface of the clavicle was quickly found and successfully protected, and no obvious abnormal skin sensations were noted after the operation. In the third case, there was no abnormal sensation in most of the associated skin except for the innervation area of the lateral branch of the supraclavicular nerve.

Conclusions

The medial and intermediate branches of the supraclavicular nerve could be located over the skin by ultrasound, and this could be helpful in quickly isolating these nerves intraoperatively. Retaining the corresponding skin can protect the function of these nerve branches and effectively reduce the area of skin numbness after surgery.

Effect of Bilateral Superficial Cervical Plexus Block on Postoperative Analgesic Consumption in Patients Undergoing Thyroid Surgery

Purpose

Patients complain of moderate-intensity pain following thyroid surgery. Superficial cervical plexus block (SCPB) can be employed as a component of multimodal analgesia after thyroid surgery. This double-blind, randomized study aimed to compare the effects of bilateral SCPB (BSCPB) on postoperative analgesic requirements following thyroid surgery.

Methods

A total of 60 American Society of Anesthesiologists (ASA) I-II patients who underwent elective total thyroidectomy under general anesthesia were randomly assigned to Group 1 and Group 2. After inducing general anesthesia, BSCPB was not administered to Group 1, whereas BSCPB was administered using a three-point injection technique with 0.5% levobupivacaine in Group 2. Patient-controlled analgesia (PCA) was applied by using tramadol in both groups for postoperative analgesia. Tenoxicam was administered as rescue analgesic to patients in case of numeric rating scale (NRS) >4. The postoperative consumption of tramadol, rescue analgesic requirement, and hoarseness, hematoma, signs of local anesthetic toxicity were recorded.

Results

The consumption of tramadol for PCA at two, six, 12, and 24 hours postoperatively, NRS scores in the recovery room, and the number of patients who used tenoxicam as rescue analgesic were significantly lower in Group 2 than in Group 1. The hemodynamic values were similar between the groups.

Conclusions

Our study demonstrates that BSCPB, when applied as a component of multimodal analgesia, is an effective method for reducing the analgesic requirements following thyroid surgery.

The distributed pattern of the neurovascular structures around clavicle to minimize structural injury in clinical field: anatomical study

INTRODUCTION

The aim of this study was to determine the location and distribution pattern of neurovascular structures superior and inferior to the clavicle by detailed dissection.

METHODS

Fifteen adult non-embalmed cadavers with a mean age of 71.5 years were studied. For measurements, the most prominent point of the sternal end of the clavicle (SEC) on anterior view and the most prominent point of the acromial end of the clavicle (AEC) were identified and divided five equal sections before dissection. A line connecting the SEC and AEC was used as a reference line. The surrounding neurovascular structures were investigated.

RESULTS

The supraclavicular nerve was mainly distributed in the second and the third sections (distribution frequency: 41.30% and 30.43%, respectively) from AEC. Branches of the thoracoacromial artery were mainly distributed in the second, third, and fourth sections (distribution frequency: 21.15%, 26.92%, and 28.85%, respectively). Branches of the subclavian vein were mainly distributed in the third and fourth sections (distribution frequency: 23.26 and 30.23%, respectively). Distribution frequency of subclavian vein, subclavian artery, and brachial plexus ranged from 31.3 to 57.5%.

DISCUSSION

When the clavicle was divided into five sections, there was relatively little distribution of neurovascular damage in the first section or the fifth section. This study reveals the average location of subclavian vein with artery and brachial plexus. Results of this study could be used as reference during surgery.

Cervical plexus block

Cervical plexus blocks (CPBs) have been used in various head and neck surgeries to provide adequate anesthesia and/or analgesia; however, the block is performed in a narrow space in the region of the neck that contains many sensitive structures, multiple fascial layers, and complicated innervation. Since the intermediate CPB was introduced in addition to superficial and deep CPBs in 2004, there has been some confusion regarding the nomenclature and definition of CPBs, particularly the intermediate CPB. Additionally, as the role of ultrasound in the head and neck region has expanded, CPBs can be performed more safely and accurately under ultrasound guidance. In this review, the authors will describe the methods, including ultrasound-guided techniques, and clinical applications of conventional deep and superficial CPBs; in addition, the authors will discuss the controversial issues regarding intermediate CPBs, including nomenclature and associated potential adverse effects that may often be neglected, focusing on the anatomy of the cervical fascial layers and cervical plexus. Finally, the authors will attempt to refine the classification of CPB methods based on the target compartments, which can be easily identified under ultrasound guidance, with consideration of the effects of each method of CPB.

Clavicula fractures: considerations when plating

The preferred treatment of clavicula midshaft fractures in adults has gone from being very conservative into surgery being frequently recommended. However, based on recent meta-analysis favorable outcome with internal fixation is not as consistent as previously reported. Probably due to a combination of indications for surgery becoming too wide and surgery being performed by a wider group of surgeons. When using plating for clavicula fractures there are several considerations to consider to improve outcome while reducing the risk for complications. Traditionally a horizontal approach along the clavicula is used as it provides good exposure. However, this incision is associated with a high risk for permanent anterior chest wall numbness that might be very disturbing for patients. A vertical incision can instead be used. Plates are traditionally placed in a superior position. An alternative can be an anterior-inferior position that allows better soft tissue coverage, less risk for hardware protrusion, longer screws can be used and the risk for damaging the underlying neurovascular bundle is reduced. Angle-stable screw-plate systems has not in a convincing way shown any benefit in clavicula fractures. In part because most patients have good bone quality where conventional screws will be sufficient.

Shoulder Morbidity in Patients after Head and Neck Reconstruction with the Pedicled Supraclavicular Island Flap

Supplemental Digital Content is available in the text.

Background:

The pedicled supraclavicular artery island flap (SCAIF) for reconstruction of the head and neck has been shown to be a pliable alternative to established pedicled flaps, such as the pectoralis major myocutaneous flap. Because there are limited published data regarding shoulder morbidity after SCAIF procedure, we aimed to investigate it with 2 established questionnaires for the upper extremity [Constant-Murley score and Disabilities of the Arm, Shoulder and Hand Outcome Measure (DASH) score].

Methods:

The authors designed and implemented a retrospective cohort study of patients who received a defect reconstruction by SCAIF. Analyzed parameters were demographics, comorbidities, donor-site morbidity and shoulder morbidity in terms of range of motion, pain, strength, and daily activities evaluated and compared between the donor site and contralateral arm.

Results:

Of the 61 consecutively performed head and neck reconstructions with SCAIF, 20 met inclusion criteria (curative intended treatment, head and neck squamous cell cancer, follow-up time more than 4 months). Mean follow-up was 17.3 months (±10.4 months) ranging from 4–35 months. Donor-site complication rate was low with 5% major (surgical revision) and 30% minor complications (conservative management). Overall Constant-Murley-Score (P = 0.334), pain (P = 0.150), overall range of motion (P = 0.861), and strength of the extremity (P = 0.638) of the shoulder receiving a SCAIF showed no significant differences to the contralateral extremity. Mean of Disabilities of the Arm, Shoulder and Hand Outcome Measure score was 32.5 (±28.6).

Conclusion:

The results of the present study suggest very low shoulder morbidity in patients after SCAIF procedure with no significant functional impairment of the donor shoulder compared with the contralateral side.

Nerve conduction study of the three supraclavicular nerve branches

INTRODUCTION

We describe a new nerve conduction study technique with reference values for the 3 branches of the supraclavicular nerve (SCN) in young healthy subjects and application of it in 2 patients.

METHODS

The recording electrode was placed on the posterior border of the sternocleidomastoid muscle, 6-7 cm from the sternoclavicular joint. SCN branches were stimulated below the clavicle, 2.5, 7, and 10.5 cm lateral to the sternoclavicular joint.

RESULTS

Twenty healthy volunteers (10 men), 19-38 years, mean 25.9 years (SD 6.3), and 2 patients with SCN lesions were studied. The mean conduction velocities of the SCN branches were 70-78 m/s (SD 8-10 m/s), and amplitudes 3-4 µV (SD 0.9-2.0 µV). There were no side-to-side or gender differences.

DISCUSSION

The 3 SCN branches could be studied in all subjects. We provide reference values for young subjects. This new method was useful in verifying SCN lesions in 2 patients. Muscle Nerve 58: 300-303, 2018.

The Influence of Incision Type on Patient Satisfaction After Plate Fixation of Clavicle Fractures

BACKGROUND

Open reduction and internal fixation (ORIF) of the clavicle is a common procedure that has been shown to have improved outcomes over nonoperative treatment. Several incisions can be used to approach clavicle fractures, the decision of which is variable among surgeons.

PURPOSE

To compare patient satisfaction and subjective outcomes between patients with a longitudinal incision versus those with a necklace incision for the treatment of diaphyseal clavicle fractures.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Thirty-six patients with a diaphyseal clavicle fracture (Orthopaedic Trauma Association type 15-B) were treated by 1 of 7 orthopaedic surgeons. The intervention was ORIF with anatomic contoured plates. Patients were divided into a necklace incision group and a longitudinal incision group depending on the surgical approach used. Medical records were reviewed, and participants completed an online survey with questions related to pain, numbness, scar appearance, and satisfaction. Function was assessed using the American Shoulder and Elbow Surgeons score. Statistical significance was determined with P < .05.

RESULTS

There were 16 patients in the necklace incision group and 20 in the longitudinal incision group. Patients in the necklace incision group were significantly more satisfied with the appearance of their scars (P = .01), which correlated with overall satisfaction (P = .05). There were no differences in overall satisfaction, pain, numbness, or reoperation rates for hardware removal between the necklace (6%) and longitudinal groups (15%).

CONCLUSION

Patients undergoing clavicle ORIF with a necklace incision are more satisfied with their scar appearance than those with a longitudinal incision. The overall satisfaction, rate of numbness, and plate removal were similar in both groups.

Tunnels and grooves for supraclavicular nerves within the clavicle: review of the literature and clinical impact

Perforation of the clavicle by supraclavicular nerves is a common anatomical variation. This variation has been reported in several studies based on post-mortem, surgical and radiologic findings, with an overall frequency between 1 and 6.6 %. The penetrating branch passes either through a bony tunnel or a groove on the superior surface of the bone. Entrapment neuropathy of the perforating branch is a documented clinical entity reported in the literature. The intraosseous course of the supraclavicular nerves makes them vulnerable to injury in case of clavicular fractures or during surgical manipulations of these fractures. Furthermore, this variation should be taken into account during the interpretation of chest and shoulder radiographs. The purpose of the current study is to perform an extended review of the relevant literature, highlighting the clinical impact of this variation, as well as to incorporate our own findings into them.

A novel method to measure sensory nerve conduction of the supraclavicular nerve

INTRODUCTION

In this report we describe a reliable method for recording sensory nerve action potentials (SNAPs) of the supraclavicular nerve.

METHODS

Supraclavicular SNAPs were recorded by placing a surface active electrode at the posterior border of the sternocleidomastoid muscle at a distance of 6 cm from the sternoclavicular joint. The nerve was stimulated at the lower border of the clavicle 4.5 cm lateral to the sternoclavicular joint.

RESULTS

Supraclavicular SNAPs were recorded bilaterally from 20 healthy volunteers. Mean onset latency was 1.0 ± 0.2 ms, and mean peak latency was 1.4 ± 0.3 ms. Mean baseline-to-peak amplitude for the SNAPs was 6.1 ± 2.2 µV, and mean maximum conduction velocity was 59.8 ± 6.2 m/s. The mean percentage of side-to-side difference in amplitude was 12.9 ± 11.0%.

CONCLUSIONS

Supraclavicular SNAPs could be obtained in all normal subjects. Assessment of supraclavicular nerve conduction is very useful in the diagnosis of supraclavicular neuropathy.

Arthroscopically assisted percutaneous fixation of displaced midclavicular fracture using a Knowles pin

Clavicle fractures are common traumatic injuries of the shoulder girdle, with surgery being the recommended treatment for some displaced midshaft fractures. Open surgery is widely used; however, the primary concerns of this procedure include cosmetic problems and incisional complications, such as wound dehiscence, infection, numbness, and sensitivity. A new arthroscopically assisted technique was developed, in which the Knowles pin was used for percutaneous fixation to treat the displaced midclavicular fracture. This technique is an attractive alternative treatment option for midclavicular fractures.

Clavicle fractures - incidence of supraclavicular nerve injury

Objective

To analyze retrospectively 309 fractures in the clavicle and the relation with injury of the supraclavicular nerve after trauma.

Methods

It was analyzed 309 patients with 312 clavicle fractures. The Edinburgh classification was used. Four patients had fractures in the medial aspect of the clavicle, 33 in the lateral aspect and 272 in the diaphyseal aspect and three bilateral fractures.

Results

255 patients were analyzed and five had paresthesia in the anterior aspect of the thorax. Four patients had type 2 B2 fracture and one type 2 B1 fracture. All patients showed spontaneous improvement, in the mean average of 3 months after the trauma.

Conclusion

Clavicle fractures and/or shoulder surgeries can injure the lateral, intermediary or medial branches of the supraclavicular nerve and cause alteration of sensibility in the anterior aspect of the thorax. Knowledge of the anatomy of the nerve branches helps avoid problems in this region.

Localization of degenerative changes of the acromioclavicular joint: a cadaveric study

PURPOSE

It has not been fully clarified yet how degenerative changes occur within the acromioclavicular (AC) joint, including their localizations. The aim of this study was to clarify the localization of degenerative changes in the AC joint using cadaveric specimens.

METHODS

Thirty-eight cadaveric AC joints with the sections were cut in the coronal plane. For both the acromion and the clavicle, the joint surface was divided into upper and lower halves. Histological features including the mean thickness of cartilage, reduction of proteoglycan staining and the extent of damaged tidemark were evaluated. The shapes of intraarticular discs as well as their histological structures were also assessed, which were compared between the upper and lower halves.

RESULTS

Articular cartilage in the lower half was significantly thinner than that in the upper half for both the acromion and the clavicle (p < 0.01). Similarly, the lower half of cartilage was more degenerated than the upper half. Intraarticular discs were absent in nine joints and the meniscoid-like type in 29, which contained rich fibrocartilaginous tissues in the upper half, whereas it mainly consisted of the fibrous tissues with granulation in the lower half.

CONCLUSION

The lower half of the AC joint demonstrated more advanced degeneration than the upper half, which might reflect the greater repetitive mechanical stress. The present study revealed both the localization and the extent of degenerative changes in AC joint, which might be useful information for surgeons to determine the proper amount of bony resection in the surgical treatment for osteoarthritis of this joint.

Supraclavicular nerve entrapment syndrome

Supraclavicular nerve entrapment syndrome, although rare, should be considered among the causes of anterior shoulder girdle pain. This syndrome is usually related to anatomic variants (involving the bone structures, fibrous bands, or muscles and tendons). Computed tomography is the most useful investigation. Medications used to treat neuropathic pain may provide relief. Otherwise, a local glucocorticoid injection or even surgical decompression should be considered.

The suprascapular nerve and its articular branch to the acromioclavicular joint: an anatomic study

HYPOTHESIS

The suprascapular nerve and its articular branch innervate the acromioclavicular (AC) joint. Documenting the detailed anatomy of this innervation in the AC joint, including the pertinent surgical and anatomic relationships of the suprascapular nerve and its branches to the AC joint, will aid in the prevention of injury and the reduction of risk of denervation during shoulder surgery.

MATERIALS AND METHODS

Twelve shoulders from 6 embalmed human cadavers were bilaterally dissected to study the course of the suprascapular nerve and its motor and sensory branches.

RESULTS

The sensory branch runs superiorly to the supraspinatus muscle towards the AC joint. The average distance from the supraglenoid tubercle to the nerve at the coracoid base was 15 mm. The average distance from the coracoclavicular ligaments to the nerve at the coracoid base was 6 mm. The average distance from the spinoglenoid notch to the sensory branch at the suprascapular notch was 22 mm. The average length of the sensory branch was 30 mm. In half of the specimen shoulders, the suprascapular artery accompanied the nerve at the suprascapular notch under the transverse scapular ligament.

DISCUSSION

The innervation of the AC joint by the suprascapular nerve has been described, along with pertinent distances to anatomic landmarks. The sensory branch of the suprascapular nerve, which passed through the scapular notch inferior to the transverse scapular ligament, was found in 100% of the study specimens.

CONCLUSION

The sensory branch of the suprascapular nerve runs superiorly to the supraspinatus muscle towards the AC joint. The detailed information can be used to help decrease the risk of nerve injury during shoulder surgery and to aid in effectively diagnosing and treating AC joint-related disorders.

The anatomy of the supraclavicular nerve during surgical approach to the clavicular shaft

BACKGROUND

Surgery for clavicular shaft fractures is becoming more common but incisional and chest wall numbness reportedly occurs in 10% to 29% of patients. This may be the result of iatrogenic injury to the supraclavicular nerve branches.

QUESTIONS/PURPOSES

We determined if there was a predictable branching pattern of the supraclavicular nerve at the anterior clavicular border and determined the distances to these nerves from clavicular landmarks.

METHODS

We performed an anatomic dissection along the anterior border of the long axis of the clavicle in 37 cadavers. The branches of the supraclavicular nerve were identified at the anterosuperior clavicular border and the distances from these nerves to palpable bony landmarks were measured.

RESULTS

Ninety-seven percent of specimens had a medial and a lateral branch of the supraclavicular nerve. Nearly half (49%) possessed an additional intermediate branch. No branch was found within 2.7 cm of the sternoclavicular joint or within 1.9 cm of the acromioclavicular joint. Between these two positions, there was wide variability in nerve branch location.

CONCLUSIONS

There were two or three branches of the supraclavicular nerve crossing the clavicle 97% of the time and a wide variability of the location of these branches outside the safe zones.

CLINICAL RELEVANCE

There are safe zones within 2.7 cm of the sternoclavicular joint and 1.9 cm of the acromioclavicular joint. Between these safe zones, the location of the nerve branches is variable and the surgeon must use meticulous dissection if he or she wishes to prevent transection.

Post-operative numbness and patient satisfaction following plate fixation of clavicular fractures

INTRODUCTION AND AIM

Numbness across the shoulder and upper chest wall is a frequent complication following plate fixation of clavicular shaft fractures. This is usually attributed to damage to branches of the supraclavicular nerve caused by the surgical approach. We investigate whether the use of an incision perpendicular to the long axis of the clavicle (vertical incision) rather than one parallel to it (horizontal incision) is associated with reduced post-operative numbness and improved patient satisfaction.

METHODS

We retrospectively assessed a group of patients who underwent plate fixation of a fractured clavicle at our institution. Using a patient-completed questionnaire, we compared differences in numbness, scar satisfaction, pain, and overall satisfaction with the operation, between those who received a horizontal incision (n=21) versus those treated using a vertical incision (n=14).

RESULTS

The likelihood of experiencing post-operative numbness was less in the vertical incision group. Those who had undergone vertical incisions also reported a significantly reduced degree of numbness and significantly less awareness of the numbness with clothing and shoulder straps. There was no statistically significant difference between the groups in terms of pain and scar satisfaction. Patients who reported being most bothered by their numbness also tended to report the highest dissatisfaction with the operation.

CONCLUSION

Vertical incisions for plate fixation of clavicular shaft fractures may be associated with reduced post-operative numbness and avoid some cases of patient dissatisfaction. Surgeons should consider using this approach in plate fixation of clavicle fractures.