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

Use of Distal Clavicle Autograft in the Treatment of Os Acromiale Open Reduction Internal Fixation: A Surgical Case Report

CASE

We present a case of a 21-year-old male patient with a symptomatic os acromiale treated with open reduction internal fixation with distal clavicle autograft. The patient presented with right shoulder pain after a motor vehicle accident with tenderness over the acromion. Radiographs demonstrated an os meso-acromion with corresponding edema on Magnetic Resonance Imaging (MRI). The patient recovered uneventfully with radiographic fusion at 8 months of the os acromiale site.

CONCLUSION

This case used the excised distal clavicle as autograft. This technique has the added advantage of harvesting autograft from the same surgical approach and potential mechanical advantage of offloading the os acromiale site to promote healing.

Variations in the Course and Diameter of the Suprascapular Nerve: Anatomical Study

(1) Background: Suprascapular neuropathy is an important factor contributing to shoulder pain. Given the prevalence of nerve injury and nerve block in the suprascapular notch region, as well as the frequency of arthroscopic procedures on the suprascapular notch, which are recommended in shoulder pain management, its morphology is relevant from a clinical perspective. (2) Methods: Suprascapular nerve course was studied in twelve shoulders by dissection. Its diameter was measured at omohyoid level, proximal to the suprascapular notch and distal to the spinoglenoid notch. A multi-vari chart was used in order to descriptively visualize the results. The variations found were analyzed with a mixed linear model. (3) Results: In two of the six subjects, the suprascapular nerve was divided into two motor branches proximal to the superior transverse scapular ligament. An increase in diameter around the suprascapular notch was detected, with an estimated difference between diameter means of 2.008 mm at the suprascapular notch level and 2.047 mm at the spinoglenoid notch level. (4) Conclusions: A difference in the estimated diameter detected and the fact that the motor branches, which innervate supraspinatus and infraspinatus muscle, were divided proximal to the suprascapular notch may be relevant in the diagnosis and treatment of suprascapular neuropathy and arthroscopic procedures.

Entrapment Neuropathies of the Shoulder

Entrapment neuropathies of the shoulder most commonly involve the suprascapular or axillary nerves, and they primarily affect the younger, athletic patient population. The extremes of shoulder mobility required for competitive overhead athletes, particularly in the position of abduction and external rotation, place this cohort at particular risk. Anatomically, the suprascapular nerve is most prone to entrapment at the level of the suprascapular or spinoglenoid notch; the axillary nerve is most prone to entrapment as it traverses the confines of the quadrilateral space.Radiographs should be ordered as a primary imaging study to evaluate for obvious pathology occurring along the course of the nerves or for pathology predisposing the patient to nerve injury. Magnetic resonance imaging plays a role in not only identifying any mass-compressing lesion along the course of the nerve, but also in identifying muscle signal changes typical for denervation and/or fatty atrophy in the distribution of the involved nerve.

Clinical implications of the distinct anatomy and innervation of the long head biceps tendon

The proximal long head of the biceps tendon (LHBT) has been recognized as a well-known cause of anterior shoulder pain. Previous studies have identified a heterogeneous distribution of nerve fibers in the tendon, with a higher abundance of fibers in the proximal and distal thirds of the tendon. This suggests that the proximal portion of the long head biceps tendon may have a different source of innervation than the distal portion. The purpose of this study was to review the innervation of the superior shoulder and identify the proximal source of sensory innervation of the LHBT. The relevant hypothesis was that the suprascapular nerve (SSN) was the proximal source of sensory innervation to the LHBT. Gross and microdissection of eight fresh human cadaver shoulders were performed, with a focus on the distal articular branches of suprascapular nerve (SSN). Utilizing 3.5× magnification loupes, the medial subacromial branch (MSAb), lateral subacromial branch (LSAb), and posterior glenohumeral branch (PGHb) were identified and followed distally to their terminal branches. In all specimens, terminal branches of the lateral subacromial branch supplied the proximal LHBT and the superior labrum. Terminal branches of the posterior glenohumeral branch supplied the posterosuperior labrum and, to a lesser extent, the labral attachment of the LHBT. These findings confirm branches of the suprascapular nerve as the proximal source of sensory innervation to the LHBT. Identification of the suprascapular nerve as a source of proximal innervation of the LHBT may influence clinical decisions related to nonsurgical and surgical intervention, nerve blocks, and nerve ablation procedures.

Overview of Innervation of Shoulder and Acromioclavicular Joints

Detailed understanding of the course and location of articular nerves supplying the shoulder joint is paramount to the successful utilization of image-guided radiofrequency ablation to manage chronic shoulder pain. In this article, the origin, course, and relationship to anatomic landmarks of articular nerves supplying the shoulder and acromioclavicular joints are discussed. The shoulder joint capsule was consistently reported to receive innervation from multiple sources including the suprascapular, axillary, subscapular, and lateral pectoral nerves. The acromioclavicular joint received innervation from suprascapular and lateral pectoral nerves. The consistent relationship of articular branches to anatomic landmarks provides the basis for specific image-guided targeting.

Putting Our Shoulder to the Wheel: Current Understanding and Gaps in Nerve Ablation for Chronic Shoulder Pain

Shoulder pain is prevalent, burdensome, and functionally limiting, with diverse pathology and associated treatments. This narrative review provides a summary of relevant neuroanatomy, proposed ablation targets, safety and efficacy concerns for ablation targets, and current research gaps. Radiofrequency ablation (RFA) of peripheral sensory nerves is a well-established treatment for chronic joint and spine pain, but it is relatively nascent for shoulder pain. Cadaveric studies demonstrate the shoulder joint is innervated by articular branches of the suprascapular nerve, axillary nerve, lateral pectoral nerve, and upper and lower subscapular nerves. Shoulder articular branch RFA appears to be a safe and effective treatment for chronic shoulder pain, but there are currently no widely accepted protocols for ablation targets. There are also no randomized controlled trials (RCT) assessing safety and efficacy of proposed targets or the prognostic value of articular blocks. Future research studies should prioritize categorical data, use appropriate functional measures as primary endpoints, and would ideally include a large-scale RCT.

Diagnostic block and radiofrequency ablation of the acromial branches of the lateral pectoral and suprascapular nerves for shoulder pain: a 3D cadaveric study

BACKGROUND AND OBJECTIVES

Acromial branches of the lateral pectoral and suprascapular nerves have been proposed as targets for diagnostic block and radiofrequency ablation to treat superior shoulder pain; however, the nerve capture rates of these procedures have not been investigated. The objectives of this study were to use dissection and 3D modeling technology to determine the course of these acromial branches, relative to anatomical landmarks, and to evaluate nerve capture rates using ultrasound-guided dye injection and lesion simulation.

METHODS

Ultrasound-guided dye injections, targeting the superior surface of coracoid process and floor of supraspinous fossa, were performed (n=5). Furthermore, needles targeting the superior and posterior surfaces of the coracoid process were placed under ultrasound guidance to simulate needle electrode position (n=5). Specimens were dissected, digitized, and modeled to determine capture rates of acromial branches of lateral pectoral and suprascapular nerves.

RESULTS

The course of acromial branches of lateral pectoral and suprascapular nerves were documented. Dye spread capture rates: acromial branches of lateral pectoral and suprascapular nerves were captured in all specimens. Lesion simulation capture rates: (1) when targeting superior surface of coracoid process, the entire acromial branch of lateral pectoral nerve was captured in all specimens and (2) when targeting posterior surface of coracoid process, the acromioclavicular and bursal branches of acromial branch of suprascapular nerve were captured in all specimens; coracoclavicular branch was captured in 3/5 specimens.

CONCLUSIONS

This study supports the anatomical feasibility of ultrasound-guided targeting of the acromial branches of lateral pectoral and suprascapular nerves. Further clinical investigation is required.

Morphometric study of suprascapular notch and scapular dimensions in Ugandan dry scapulae with specific reference to the incidence of completely ossified superior transverse scapular ligament

BACKGROUND

Understanding of suprascapular notch (SSN) anatomy and relationship with scapular dimensions are vital in diagnosis, prevention, and assessment of suprascapular nerve entrapment syndrome. The study aimed to assess morphometry of suprascapular notch and scapular dimensions in Ugandan dry scapulae with specific reference to scapulae with completely ossified superior transverse scapular ligaments.

METHODS

This was a cross-sectional analytical study conducted on 50 Ugandan dry scapulae. SSN types and prevalence of completely ossified superior transverse scapular ligament among dry scapulae were quantified and compared with previous data. Scapular dimensions were assessed by measuring scapular length (A), scapular width (B), glenoid length (C), and glenoid width (D). One-way ANOVA was used to compare scapular dimensions of scapulae with different SSN types, and Spearman's correlation coefficient was used to evaluate the correlation coefficient of scapular dimensions amongst groups.

RESULTS

Superior transverse scapular ligament (STSL) was completely ossified in 8% of cases. There was no significant (P > 0.05) difference between scapular dimensions of scapulae with completely ossified STSL compared to scapulae with other SSN types. Scapulae with completely ossified STSL showed strong negative (r = - 0.89137, r = - 0.877) correlations for its A, B respectively compared against D, this finding was not true to scapulae of other SSN types. Also, there were strong positive or negative (r > 0.7, r > - 0.7) correlations: for A, types I and III compared to type VI; for B, types I, III compared to VI; for C, type IV and VI; and for D, type III and VI.

CONCLUSIONS

The prevalence of completely ossified STSL is moderately high in the Ugandan population. Characteristics of the scapula (scapular dimensions) are not 'vital' but rather important or relevant for shoulder pathology with specific reference to suprascapular nerve entrapment syndrome due to completely ossified superior transverse scapular ligaments. Further correlation analyses of scapular dimensions of different SSN types in different populations are important.

"Suprascapular canal": Anatomical and topographical description and its clinical implication in entrapment syndrome

BACKGROUND

Suprascapular nerve (SN) entrapment syndrome accounts for 1-2% of all shoulder pain. The SN travels within a space between the suprascapular notch (SSN) and the spinoglenoid notch (SGN).

PURPOSE

To report a detailed topographical study of the suprascapular canal (SSC) and ultimately sort the different types of SN entrapment by its anatomical localization within the canal.

BASIC PROCEDURES

Observational study on 30 free dissected limbs of formaldehyde-fixed cadavers. The SN and vessels were traced as they passed through the SSC and the boundaries of the SSC were observed and documented. The SSC was then exposed by reflecting away the bordering muscles. Dimensions of the SSC as well as parameters of the SSN and SGN were measured using a digital caliper. Finally, a thorough literature review was made to survey the SN entrapment occurrence by site.

MAIN FINDINGS

The SSC is situated in the spinoglenoid fossa, has an average width of 13 mm, and runs underneath the supraspinatus muscle with an average distance of 25 mm between the SSN and SGN sloping in an infero-postero-lateral direction. The first segment represents the SSC entrance site and is composed of two spaces: osteofibrous and musculofibrous. The second segment is bordered by the supraspinatus muscle fascia, lateral margin of the supraspinous fossa, glenohumeral joint capsule, and the bony surface of the scapula (spinoglenoid fossa). This represents the SSC passage site. The third segment represents the SSC exit site around the spinoacromial arch at the SGN.

PRINCIPAL CONCLUSIONS

The SSC is defined as an osteofibrous canal running between the SSN and SGN enclosed by the supraspinatus fascia. It is anatomically composed of three segments: an entrance, a passage, and an exit. The distal SN passes through the SSC via five intervals that correspond to five potential sites of anatomical nerve entrapment: at the pre-entrance site, entrance site, passage site, exit site, and post-exit site. Each of those sites was found to be associated with specific causes and forms of entrapment.

Innervation of the acromioclavicular joint by the suprascapular nerve

BACKGROUND

The suprascapular nerve is largely responsible for the majority of the sensory innervation of the acromioclavicular joint. In this anatomical study, we describe, in detail, the anatomy of the sensory innervation of the acromioclavicular joint by the branches of the suprascapular nerve.

METHODS

Twenty-seven shoulders from 17 cadaveric specimens were carefully dissected to identify the course of the suprascapular nerve, with the main focus being on the sensory innervation of the acromioclavicular joint. Nine specific measurements of the acromioclavicular joint sensory nerves were made of each shoulder in relation to distinct anatomical landmarks to determine the mean location and course of these nerves.

RESULTS

In all 27 shoulders (100%), a sensory branch to the acromioclavicular joint with a proximal origin from the suprascapular nerve could be depicted ("first sensory branch"). The mean length of this branch was 4.3 cm (range: 3.3-5.3 cm). In 14 shoulders (52%), a further sensory branch of the suprascapular nerve innervating the posterior acromioclavicular joint capsule could be identified ("second sensory branch").

DISCUSSION

A detailed anatomical description of the sensory innervation of the acromioclavicular joint from suprascapular nerve branches was performed, which can potentially aid in the development of more focused anesthetic blockades and acromioclavicular joint denervation procedures.

Diaphragm-sparing nerve blocks for shoulder surgery, revisited

Although interscalene brachial plexus block (ISB) remains the gold standard for analgesia after shoulder surgery, the inherent risks of ipsilateral phrenic nerve block and hemidiaphragmatic paralysis (HDP) limit its use in patients with preexisting pulmonary compromise. In a previous Daring Discourse (2017), our research team has identified potential diaphragm-sparing alternatives to ISB for patients undergoing shoulder surgery. In recent years, the field has been fertile with research, with the publication of multiple randomized controlled trials investigating supraclavicular blocks, upper trunk blocks, anterior suprascapular nerve blocks, costoclavicular blocks, and combined infraclavicular-suprascapular blocks. To date, the cumulative evidence (pre-2017 and post-2017) suggests that costoclavicular blocks may provide similar postoperative analgesia to ISB coupled with a 0%-incidence of HDP. However, in light of the small number of patients recruited by the single study investigating costoclavicular blocks, further confirmatory trials are required. Moreover, future investigation should also be undertaken to determine if costoclavicular blocks could achieve surgical anesthesia for shoulder surgery. Anterior suprascapular nerve blocks have been demonstrated to provide surgical anesthesia and similar analgesia to ISB. However, their risk of HDP has not been formally quantified. Of the remaining diaphragm-sparing nerve blocks, supraclavicular blocks (with local anesthetic injection posterolateral to the brachial plexus), upper trunk blocks, and combined infraclavicular-anterior suprascapular blocks merit further investigation, as they have been shown to achieve similar analgesia to ISB, coupled with an HDP incidence <10%.

Evaluation of suprascapular nerve radiofrequency ablation protocols: 3D cadaveric needle placement study

BACKGROUND AND OBJECTIVES

Image-guided intervention of the suprascapular nerve is a reported treatment to manage chronic shoulder joint pain. The suprascapular nerve is conventionally targeted at the suprascapular notch; however, targeting of its branches, the medial and lateral trunks, which are given off just posterior to the notch has not been considered. Since the lateral trunk supplies the posterior supraspinatus and articular branches to the glenohumeral joint capsule, while the medial trunk provides motor innervation to the anterior region, it may be possible to preserve some supraspinatus activation if the medial trunk is spared. The main objective was to investigate whether midpoint between suprascapular and spinoglenoid notches is the optimal target to capture articular branches of lateral trunk while sparing medial trunk.

METHODS

In 10 specimens, using ultrasound guidance, one 17 G needle was placed at the suprascapular notch and a second at midpoint between suprascapular and spinoglenoid notches. The trunks and needles were exposed in the supraspinous fossa, digitized and modeled in 3D. Lesion volumes were added to the models to asses medial and lateral trunk capture rates. Mean distance of needle tips to origin of medial trunk was compared.

RESULTS

Conventional notch technique captured both lateral and medial trunks, whereas a midpoint technique captured only lateral trunk. Mean distance of needles from the origin of medial trunk was 5.10±1.41 mm (notch technique) and 14.99±5.53 mm (midpoint technique).

CONCLUSIONS

The findings suggest that the midpoint technique could spare medial trunk of suprascapular nerve, while capturing lateral trunk and articular branches. Further clinical investigation is required.

Sensory innervation of the subacromial bursa by the distal suprascapular nerve: a new description of its anatomic distribution

BACKGROUND

Sensory innervation to the shoulder provided by the distal suprascapular nerve (dSSN) remains the subject of debate. The purpose of this study was to establish consensus with respect to the anatomic features of the sensory branches of the dSSN. The relevant hypothesis was that the dSSN would give off 3 sensory branches providing innervation to the posterior glenohumeral (PGH) capsule, the subacromial bursa, in addition to the coracoclavicular and acromioclavicular ligaments.

METHODS

The division, course, and distribution of the sensory branches that originated from the dSSN and innervated structures around the shoulder joint were examined macroscopically by dissecting 37 shoulders of 19 fresh-frozen cadavers aged of 83.0 years (range, 74-98 years).

RESULTS

The 37 dSSN provided 1 medial subacromial branch (MSAb), 1 lateral subacromial branch (LSAb), and 1 PGH branch (PGHb) to the shoulder joint. This arrangement allowed for bipolar-MSAb and LSAb-innervation of the subacromial bursa, acromioclavicular (MSAb and LSAb) and coracoclavicular (MSAb) ligaments, as well as the PGH capsule (PGHb).

CONCLUSIONS

The dSSN provided 2 subacromial branches and 1 PGHb to the shoulder joint. This arrangement allowed for bipolar-MSAb and LSAb-innervation of the subacromial bursa, acromioclavicular and coracoclavicular ligaments, as well as the PGH capsule.

MRI diagnosis of suprascapular neuropathy using spinoglenoid notch distension

PURPOSE

To assess the use of a spinoglenoid notch distension measurement as a radiographic marker on MRI to aid the diagnosis of suprascapular neuropathy.

METHODS

Spinoglenoid notch distension was compared on MRI by blinded independent observers for two patient cohorts: one group with an electromyography/nerve conduction study confirmed diagnosis of suprascapular neuropathy who underwent arthroscopic suprascapular nerve decompression, and a control group of patients aged 18-30 years with a normal shoulder MRI.

RESULTS

Sixty suprascapular nerve patients (average age 52 years) were compared to 47 control patients (average age 24 years). Intra-rater and inter-rater reliability showed excellent agreement between reviewers for all measurements. There was a significant difference in the mean spinoglenoid notch distension for the SSN group (m = 8.36, SD = 2.42) compared to the control group (m = 5.7, SD = 1.56); [t(212) = 9.40, p < 0.0001].

CONCLUSION

The spinoglenoid notch distension is significantly increased in patients with suprascapular neuropathy. We hypothesize that hypertrophy of the transverse scapular ligament creates a venous obstruction resulting in varicosities of the suprascapular vein which runs with the nerve under the ligament. This distends the spinoglenoid notch and can be enlarged in cases of suprascapular neuropathy which is evident on MRI.

Anatomical study of the innervation of glenohumeral and acromioclavicular joint capsules: implications for image-guided intervention

BACKGROUND AND OBJECTIVES

In 2011, chronic shoulder joint pain was reported by 18.7 million Americans. Image-guided radiofrequency ablation has emerged as an alternative intervention to manage chronic shoulder joint pain. To optimize the effectiveness of shoulder denervation, it requires a detailed understanding of the nerve supply to the glenohumeral and acromioclavicular joints relative to landmarks visible with image guidance. The purpose of this cadaveric study was to determine the origin, course, relationships to bony landmarks, and frequency of articular branches innervating the glenohumeral and acromioclavicular joints.

METHODS

Fifteen cadaveric specimens were meticulously dissected. The origin, course, and termination of articular branches supplying the glenohumeral and acromioclavicular joints were documented. The frequency of each branch was determined and used to generate a frequency map that included their relationships to bony and soft tissue landmarks.

RESULTS

In all specimens, the posterosuperior quadrant of the glenohumeral joint was supplied by suprascapular nerve; posteroinferior by posterior division of axillary nerve; anterosuperior by superior nerve to subscapularis; and anteroinferior by main trunk of axillary nerve. Less frequent innervation was found from lateral pectoral nerve and posterior cord. The acromioclavicular joint was found to be innervated by the lateral pectoral and acromial branch of suprascapular nerves in all specimens. Bony and soft tissue landmarks were identified to localize each nerve.

CONCLUSIONS

The frequency map of the articular branches supplying the glenohumeral and acromioclavicular joints, as well as their relationship to bony and soft tissue landmarks, provide an anatomical foundation to develop novel shoulder denervation and perioperative pain management protocols.

Comparison of Calcaneal Exposure Through the Extensile Lateral and Sinus Tarsi Approaches

The purpose of this study was to compare the exposure of the posterior facet with the extensile lateral (EL) approach compared with the sinus tarsi (ST) approach. We hypothesized that the ST approach will provide a similar exposure of the posterior calcaneal facet. A total of 8 sequential ST then EL approaches were performed on cadavers. Calcaneal landmarks were identified by visualization or palpation. Calibrated digital photographs of the posterior facet and lateral calcaneal body were obtained from standardized positions and used to calculate the exposed surface area. No significant difference was found in the average square area of the posterior facet exposed with the 2 approaches. Significantly more of the lateral calcaneal body was seen with the EL approach. Excluding the posterior facet superomedial quadrant, all the landmarks were visualized in 100% of approaches. The superomedial corner was visualized in significantly more of the cadavers with the EL approach and was palpable in 12.5% of the remaining cadavers in both approaches. Whereas the ST approach exposes less of the lateral wall of the calcaneus, it exposes similar amounts of the posterior facet when compared with the EL approach.

LEVELS OF EVIDENCE

Therapeutic, Level V.

Cystic lesions of peripheral nerves: Are we missing the diagnosis of the intraneural ganglion cyst?

AIM

To highlight the salient magnetic resonance imaging (MRI) features of the intraneural ganglion cyst (INGC) of various peripheral nerves for their precise diagnosis and to differentiate them from other intra and extra-neural cystic lesions.

METHODS

A retrospective analysis of the magnetic resonance (MR) images of a cohort of 245 patients presenting with nerve palsy involving different peripheral nerves was done. MR images were analyzed for the presence of a nerve lesion, and if found, it was further characterized as solid or cystic. The serial axial, coronal and sagittal MR images of the lesions diagnosed as INGC were studied for their pattern and the anatomical extent along the course of the affected nerve and its branches. Its relation to identifiable anatomical landmarks, intra-articular communication and presence of denervation changes in the muscles supplied by involved nerve was also studied.

RESULTS

A total of 45 cystic lesions in the intra or extraneural locations of the nerves were identified from the 245 MR scans done for patients presenting with nerve palsy. Out of these 45 cystic lesions, 13 were diagnosed to have INGC of a peripheral nerve on MRI. The other cystic lesions included extraneural ganglion cyst, paralabral cyst impinging upon the suprascapular nerve, cystic schwannoma and nerve abscesses related to Hansen's disease involving various peripheral nerves. Thirteen lesions of INGC were identified in 12 patients. Seven of these affected the common peroneal nerve with one patient having a bilateral involvement. Two lesions each were noted in the tibial and suprascapular nerves, and one each in the obturator and proximal sciatic nerve. An intra-articular connection along the articular branch was demonstrated in 12 out of 13 lesions. Varying stages of denervation atrophy of the supplied muscles of the affected nerves were seen in 7 cases. Out of these 13 lesions in 12 patients, 6 underwent surgery.

CONCLUSION

INGC is an important cause of reversible mono-neuropathy if diagnosed early and surgically treated. Its classic MRI pattern differentiates it from other lesions of the peripheral nerve and aid in its therapeutic planning. In each case, the joint connection has to be identified preoperatively, and the same should be excised during surgery to prevent further cyst recurrence.

Editorial Commentary: Arthroscopically Assisted Acromioclavicular Joint Reconstruction-Not Seeing Does Not Mean Do Not Worry

To minimize risks during arthroscopic-assisted reduction and internal fixation of acromioclavicular dislocation, drilling should only be performed with an anatomically reduced clavicle. This re-creates the important distances to the neurovascular structures because a posteriorly displaced clavicle reduces the distance to the suprascapular nerve. In addition, visualization is of high importance for the arthroscopic coracoid preparation, as are mini-open incisions, to create an accurate and well-placed tunnel for drilling. Last, because the highest potential risk of neurovascular injuries occurs with the drilling itself instead of the final construct, all possible assistance and supports guiding the surgeon should be used to avoid any pitfalls. Hence, radiography and arthroscopy are helpful tools to create and check precise tunnel placement. Still, there are risks, and surgeons must be aware of and mitigate against neurovascular complications.

Association of the area of sensory disturbance with the area of suprascapular nerve palsy

PURPOSE

To determine the association of the area of sensory disturbance with the area of suprascapular nerve (SSN) palsy in healthy volunteers and patients with SSN palsy.

METHODS

Five male and one female and healthy volunteers aged 23 to 44 (mean age, 32.2) years underwent an experiment of distal and proximal SSN block (at the spinoglenoid notch and suprascapular notch, respectively). A pinprick test was performed to determine pain sensation and the area of sensory disturbance. In addition, records of 21 male and 19 female patients aged 21 to 75 (mean, 54.1) years who underwent arthroscopic SSN release for SSN palsy were reviewed. The same pinprick test was performed.

RESULTS

After distal SSN block, 5 volunteers had a sensory deficit in the area below the scapular spine only, and one had no sensory deficit. After proximal SSN block, the sensory deficit spread to both lateral and medial sides above and below the scapular spine. In the 40 patients with SSN palsy, only 5 (12.5%) patients exhibited no sensory deficit above the scapular spine; 4 of them had ganglion cysts and one had entrapment of the nerve at the spinoglenoid notch. In 30 patients with palsy at the suprascapular notch, all had sensory deficit in the lateral side above the scapular spine. In 5 patients with ganglion and one patient with palsy at the spinoglenoid notch, sensory deficit was noted below (and not above) the scapular spine in all patients except for one.

CONCLUSION

The area of sensory disturbance is associated with the area of SSN palsy.

Distribution of the axillary nerve to the subacromial bursa and the area around the long head of the biceps tendon

PURPOSE

Patients with a shoulder disorder often complain of pain on the anterior or lateral aspect of the shoulder. Such pain has been thought to originate from the suprascapular nerve. However, taking into consideration the distinctive course of the axillary nerve, the axillary nerve is likely to supply branches to the structure around the shoulder joint. This study was conducted to clarify the division, course, and distribution of the branches which originate from the axillary nerve and innervate structures around the shoulder joint.

METHODS

The division, course, and distribution of the branches which originate from the axillary nerve and innervate structures around the shoulder joint were examined macroscopically by dissecting 20 shoulders of 10 adult Japanese cadavers.

RESULTS

The thin branches from the anterior branch of the axillary nerve were distributed to the subacromial bursa and the area around the long head of the biceps tendon. The branches from the main trunk of the axillary nerve or the branch to the teres minor muscle were distributed to the infero-posterior part of the shoulder joint.

CONCLUSION

The pain on the anterior or lateral aspect of the shoulder, which has been thought to originate from the suprascapular nerve, might be related to the thin branches which originate from the axillary nerve and innervate the subacromial bursa and the area around the long head of the biceps tendon.

CLINICAL RELEVANCE

These results would be useful to consider the cause of the shoulder pain or to prevent the residual pain after the biceps tenodesis.

Long-term outcome of accessory nerve to suprascapular nerve transfer in obstetric brachial plexus lesion: functional, morphological, and electrophysiological results

PURPOSE

An accessory to suprascapular nerve (XIN-SSN) transfer is considered in patients with obstetric brachial plexus lesion who fail to recover active shoulder external rotation. The aim of this study was to evaluate the quality of extraplexal suprascapular nerve neurotization and to perform a detailed analysis of the infraspinatus muscle (IM) and shoulder external rotation.

METHODS

A XIN-SSN transfer was performed in 14 patients between 2000 and 2007. Patients had been operated at the age of 3.7 ± 2.8 years. Follow-up examinations were conducted up to 8.5 ± 2.5 years. Magnetic resonance imaging was performed to investigate muscle trophism. Fatty muscle degeneration of the IM was classified according to the Goutallier classification. We conducted nerve conduction velocity studies of the suprascapular nerve and needle electromyography of the IM to assess pathologic spontaneous activity and interference patterns. Active glenohumeral shoulder external rotation and global shoulder function were evaluated using the Mallet score.

RESULTS

Postoperatively, growth of the IM increased equally on the affected and unaffected sides, although significant differences of muscle thickness persisted over time. There was only grade 1 or 2 fatty degeneration pre- and postoperatively. Electromyography of the IM revealed a full interference pattern in all except one patient, and there was no pathological spontaneous activity. Glenohumeral external rotation as well as global shoulder function increased significantly.

CONCLUSION

Our results indicate that the anastomosis after XIN-SSN transfer is functional and that successful reinnervation of the infraspinatus muscle may enable true glenohumeral active external rotation.

The role of the peripheral and central nervous systems in rotator cuff disease

Rotator cuff (RC) disease is an extremely common condition associated with shoulder pain, reduced functional capacities, and impaired quality of life. It primarily involves alterations in tendon health and mechanical properties that can ultimately lead to tendon failure. RC tendon tears induce progressive muscle changes that have a negative impact on surgical reparability of the RC tendons and clinical outcomes. At the same time, a significant base of clinical data suggests a relatively weak relationship between RC integrity and clinical presentation, emphasizing the multifactorial aspects of RC disease. This review aims to summarize the potential contribution of peripheral, spinal, and supraspinal neural factors that may (1) exacerbate structural and functional muscle changes induced by tendon tear, (2) compromise the reversal of these changes during surgery and rehabilitation, (3) contribute to pain generation and persistence of pain, (4) impair shoulder function through reduced proprioception, kinematics, and muscle recruitment, and (5) help explain interindividual differences and response to treatment. Given the current clinical and scientific interest in peripheral nerve injury in the context of RC disease and surgery, we carefully reviewed this body of literature with a particular emphasis on suprascapular neuropathy that has generated a large number of studies in the past decade. Within this process, we highlight the gaps in current knowledge and suggest research avenues for scientists and clinicians.

Pulsed radiofrequency lesioning of the axillary and suprascapular nerve in calcific tendinitis

The patient was a 45-year-female who presented with pain at right shoulder and right upper arm. The patient suffered from right shoulder and arm pain for 3 years and had pain management which was performed using medication and conservative management after she had been diagnosed with calcific tendinitis. However, substantial pain relief was not consistently achieved, and recurrence of pain was reported. Therefore, we performed right axillary nerve and suprascapular nerve block through pulsed radiofrequency. Two months after the procedure, the shoulder pain gradually subsided with the size reduction of the calcified nodule and she needed no more pain management.

The ultrasound-guided superficial cervical plexus block for anesthesia and analgesia in emergency care settings

The ultrasound-guided superficial cervical plexus (SCP) block may be useful for providers in emergency care settings who care for patients with injuries to the ear, neck, and clavicular region, including clavicle fractures and acromioclavicular dislocations. The SCP originates from the anterior rami of the C1-C4 spinal nerves and gives rise to 4 terminal branches--greater auricular, lesser occipital, transverse cervical, and suprascapular nerves--that provide sensory innervation to the skin and superficial structures of the anterolateral neck and sections of the ear and shoulder. Here we describe an ultrasound-guided technique for blockade of the SCP that is potentially well suited to emergency care settings. We present the first case description of its successful use to manage pain for a patient with an acute clavicle fracture. This case is presented to highlight one of several potential applications of this promising new technique in the emergency department.