Advancing glenohumeral dysplasia treatment in brachial plexus birth injury: the end-to-side spinal accessory to suprascapular nerve transfer technique

PURPOSE

Brachial plexus birth injury (BPBI) is a common injury with the spectrum of disease prognosis ranging from spontaneous recovery to lifelong debilitating disability. A common sequela of BPBI is glenohumeral dysplasia (GHD) which, if not addressed early on, can lead to shoulder dysfunction as the child matures. However, there are no clear criteria for when to employ various surgical procedures for the correction of GHD.

METHODS

We describe our approach to correcting GDH in infants with BPBIs using a reverse end-to-side (ETS) transfer from the spinal accessory to the suprascapular nerve. This technique is employed in infants that present with GHD with poor external rotation (ER) function who would not necessitate a complete end-to-end transfer and are still too young for a tendon transfer. In this study, we present our outcomes in seven patients.

RESULTS

At presentation, all patients had persistent weakness of the upper trunk and functional limitations of the shoulder. Point-of-care ultrasounds confirmed GHD in each case. Five patients were male, and two patients were female, with a mean age of 3.3 months age (4 days-7 months) at presentation. Surgery was performed on average at 5.8 months of age (3-8.6 months). All seven patients treated with a reverse ETS approach had full recovery of ER according to active movement scores at the latest follow-up. Additionally, ultrasounds at the latest follow-up showed a complete resolution of GHD.

CONCLUSION

In infants with BPBI and evidence of GHD with poor ER, end-to-end nerve transfers, which initially downgrade function, or tendon transfers, that are not age-appropriate for the patient, are not recommended. Instead, we report seven successful cases of infants who underwent ETS spinal accessory to suprascapular nerve transfer for the treatment of GHD following BPBI.

Risk of suprascapular nerve injury in open Trillat procedure: an anatomical study

PURPOSE

The open Trillat Procedure described to treat recurrent shoulder instability, has a renewed interest with the advent of arthroscopy. The suprascapular nerve (SSN) is theoretically at risk during the drilling of the scapula near the spinoglenoid notch. The purpose of this study was to assess the relationship between the screw securing the coracoid transfer and the SSN during open Trillat Procedure and define a safe zone for the SSN.

METHODS

In this anatomical study, an open Trillat Procedure was performed on ten shoulders specimens. The coracoid was fixed by a screw after partial osteotomy and antero-posterior drilling of the scapular neck. The SSN was dissected with identification of the screw. We measured the distances SSN-screw (distance 1) and SSN-glenoid rim (distance 2). In axial plane, we measured the angles between the glenoid plane and the screw (α angle) and between the glenoid plane and the SSN (β angle).

RESULTS

The mean distance SSN-screw was 8.8 mm +/-5.4 (0-15). Mean α angle was 11°+/-2.4 (8-15). Mean β angle was 22°+/-6.7 (12-30). No macroscopic lesion of the SSN was recorded but in 20% (2 cases), the screw was in contact with the nerve. In both cases, the β angle was measured at 12°.

CONCLUSION

During the open Trillat Procedure, the SSN can be injured due to its anatomical location. Placement of the screw should be within 10° of the glenoid plane to minimize the risk of SSN injury and could require the use of a specific guide or arthroscopic-assisted surgery.

Dislodgment of continuous suprascapular nerve block catheters after physiotherapy: A cadaver study

BACKGROUND

Continuous peripheral nerve blocks are commonly used for pain management. However, the incidence of catheter dislodgement or migration is unclear, and may be underestimated and underreported. Our objective was to assess suprascapular catheter tip positioning before and after routine simulated shoulder physiotherapy manipulation in an anatomical cadaver model.

METHOD

Eight ultrasound-guided continuous suprascapular nerve block catheters were placed in cryopreserved fresh cadavers. Computed tomography (CT) confirmed the location of the catheter tip after injection of 1 ml of contrast medium. We performed a series of standardized shoulder movements during a simulated shoulder physiotherapy session in cadavers. Following this, we administered 1 ml of methylene blue through the catheters, and then performed anatomical dissections to accurately identify the location of the catheter tips and compare them to their placement prior to the 'physiotherapy'.

RESULT

CT imaging confirmed the location of the catheter tips at the suprascapular notch in all cases. However, following physiotherapy, 2 catheters (25%) were found to have migrated - specifically, 1 was located in the supraspinatus muscle, and the other was located in the trapezius muscle.

CONCLUSION

Our findings suggest that catheter dislodgement may occur in approximately 25% of cases following simulated physiotherapy manipulation. However, further research is needed to determine the read incidence of catheter dislodgement in clinical practice.

Pulsed Radiofrequency Neuromodulation for Post-Stroke Shoulder Pain in Patients with Hemorrhagic Stroke

Objective

Post-stroke shoulder pain (PSSP) is a common complication that limits the range of motion (ROM) of the shoulder, the patient's rehabilitation and in turn, affects the patients' quality of life (QOL). Several treatment modalities such as sling, positioning, strapping, functional electrical stimulation (FES), and nerve block have been suggested in literatures, however none of the treatments had long-term effects for PSSP. In this study, the authors evaluated clinical efficacy of pulsed radiofrequency (PRF) neuromodulation on the suprascapular nerve for PSSP, and suggested it as a potential treatment with long-term effect.

Methods

This retrospective case series was conducted at a single center, a private practice institution. From 2013 to 2021, 13 patients with PSSP underwent PRF neuromodulation of the suprascapular nerve. The primary outcome measure was the visual analog scale (VAS) score. The secondary outcome measurements included the shoulder ROM, disability assessment scale (DAS), modified Ashworth scale (mAS), modified Rankin scale (mRS), and EuroQol-5 dimension-3L questionnaire (EQ-5D-3L) scores. These parameters were evaluated before PRF modulation, immediately after PRF modulation, and every three months until the final follow-up visit.

Results

Six men and seven women were enrolled, and all patients were followed-up for a minimum of 12 months. The mean VAS score was 7.07 points before PRF neuromodulation and 2.38 points immediately post-procedure. Shoulder ROM for abduction and flexion, DAS for pain, mRS, and EQ-5D-3L demonstrated marked improvement. No complications were reported.

Conclusion

PRF neuromodulation of the suprascapular nerve is an effective modality in patients with PSSP, and has long-term effect of pain relief, improvement of QOL.

A Randomised Control Trial Comparing the Outcomes of Anterior with Posterior Approach for Transfer of Spinal Accessory Nerve to Suprascapular Nerve in Brachial Plexus Injuries

Background: In brachial plexus surgery, a key focus is restoring shoulder abduction through spinal accessory nerve (SAN) to suprascapular nerve (SSN) transfer using either the anterior or posterior approach. However, no published randomised control trials have directly compared their outcomes to date. Therefore, our study aims to assess motor outcomes for both approaches. Methods: This study comprises two groups of patients. Group A: anterior approach (29 patients), Group B: Posterior approach (29 patients). Patients were allocated to both groups using selective randomisation with the sealed envelope technique. Functional outcome was assessed by grading the muscle power of shoulder abductors using the British Medical Research Council (MRC) scale. Results: Five patients who were operated on by posterior approach had ossified superior transverse suprascapular ligament. In these cases, the approach was changed from posterior to anterior to avoid injury to SSN. Due to this reason, the treatment analysis was done considering the distribution as: Group A: 34, Group B: 24. The mean duration of appearance of first clinical sign of shoulder abduction was 8.16 months in Group A, whereas in Group B, it was 6.85 months, which was significantly earlier (p < 0.05). At the 18-month follow-up, both intention-to-treat analysis and as-treated analysis were performed, and there was no statistical difference in the outcome of shoulder abduction between the approaches for SAN to SSN nerve transfer. Conclusions: Our study found no significant difference in the restoration of shoulder abduction power between both approaches; therefore, either approach can be used for patients presenting early for surgery. Since the appearance of first clinical sign of recovery is earlier in posterior approach, therefore, it can be preferred for cases presenting at a later stage. Also, the choice of approach is guided on a case to case basis depending on clavicular fractures and surgeon preference to the approach. Level of Evidence: Level II (Therapeutic).

Assessment of 2 distinct anatomical landmarks for suprascapular nerve injection: a cadaveric study

BACKGROUND

The suprascapular nerve block (SSNB) is a commonly used procedure for the management of pain in various shoulder pathologies. Both image-guided and landmark-based techniques have been utilized successfully for SSNB, though more consensus is needed regarding the optimal method of administration. This study aims to evaluate the theoretical effectiveness of a SSNB at 2 distinct anatomic landmarks and propose a simple, reliable way of administration for future clinical use.

METHODS

Fourteen upper extremity cadaveric specimens were randomly assigned to either receive an injection 1 cm medial to the posterior acromioclavicular (AC) joint vertex or 3 cm medial to the posterior AC joint vertex. Each shoulder was injected with a 10 ml methylene blue solution at the assigned location, and gross dissection was performed to evaluate the anatomic diffusion of the dye. The presence of dye was specifically assessed at the suprascapular notch, supraspinatus fossa, and spinoglenoid notch to determine the theoretic analgesic effectiveness of a SSNB at these 2 injection sites.

RESULTS

Methylene blue diffused to the suprascapular notch in 57.1% of the 1-cm group and 100% of the 3-cm group, the supraspinatus fossa in 71.4% of the 1-cm group and 100% of the 3-cm group, and the spinoglenoid notch in 100% of the 1-cm group and 42.9% of the 3-cm group.

CONCLUSION

Given its superior coverage at the more proximal sensory branches of the suprascapular nerve, a SSNB injection performed 3 cm medial to the posterior AC joint vertex provides more clinically adequate analgesia than an injection site 1 cm medial to the AC junction. Performing a SSNB injection at this location allows for an effective method of anesthetizing the suprascapular nerve.

Suprascapular nerve blockage for painful shoulder pathology - a systematic review and meta-analysis of treatment techniques

BACKGROUND

Suprascapular nerve blockade (SSNB) through injection (SSNBi) and/or pulsed radiofrequency (PRF) provide options for the management of painful shoulder pathology. Multiple techniques for delivery of SSNB are described but no consensus on optimal symptom control is available. This systematic review and meta-analysis aims to assess patient-focussed outcomes in SSNB and explore the impact of variation in the technical application of this treatment modality.

METHODS

MEDLINE, Embase and CINAHL were searched for case series, cohort studies and randomised control trials published from database inception until 28 January 2021. Articles reporting use of SSNBi or PRF for treatment of shoulder pain with a minimum 3 months follow-up were included. Patient-reported outcome measures (PROMs) were extracted and the pooled standardised mean difference (SMD), weighted by study size, was reported. Quality of methodology was assessed using Wylde's nonsummative four-point system.

FINDINGS

Of 758 references, 18 studies were included, totalling 704 SSNB. Average pain improvement at 3 months was 52.3%, with meta-analysis demonstrating a SMD of 2.37. Whereas SSNBi combined with PRF shows the greatest SMD of 2.75, this did not differ significantly from SSNBi or PRF when used as monotherapy. Location of treatment and the guidance technique used did not influence outcome.

CONCLUSION

SSNBi and PRF provide safe and effective treatment for shoulder pain, as judged by PROMs. This may be of particular value in aging or comorbid patients and with surgical restrictions during the COVID-19 pandemic. Regardless of technique, patients experience a marked improvement in pain that is maintained beyond 3 months.

The correlation of the spinoglenoid ganglion cyst size with the electrophysiological alterations of suprascapular nerve and the rotator cuff muscle power

BACKGROUND

Although various treatment options are available for spinoglenoid cyst, including conservative and surgical methods, there is no standard guideline for its surgical decompression. Thus, the purpose of the study was to correlate the size of the spinoglenoid notch ganglion cyst (GC) as revealed by magnetic resonance imaging (MRI) with electrophysiological alterations, muscle power, and pain severity, and to estimate a cut-off value of cyst size to perform a decompression.

METHODS

Between January 2010 and January 2018, the patients with a GC at the spinoglenoid notch diagnosed on MRI, and who had a minimum follow-up of 2 years after the decompression were included. Maximum cyst diameter as measured on MRI was used for comparison. Electromyography (EMG) and nerve conduction velocity (NCV) studies were performed before the surgery. Peak torque deficit (PTD) percentage compared to opposite shoulder was calculated preoperatively and at 1 year after surgery. Pain severity was estimated using visual analogue scale (VAS) preoperatively.

RESULTS

Ten (50%) of 20 patients with GC > 2.2 cm and 1 (5.9%) of 17 patients with GC < 2.2 cm showed EMG/NCV abnormalities (p = 0.019). There was a correlation between the cyst size and the positive EMG/NCV findings (Correlation coefficient (CC) = 0.535, p < 0.001). The preoperative peak torque deficit on the external rotation was correlated with the positive EMG/NCV findings (CC = 0.373, p = 0.021). The PTD was improved significantly at 1 year postoperatively in patients with a GC size >2.2 cm (p = 0.029). The cyst size was not related to the preoperative pain VAS and muscle power.

CONCLUSIONS

The spinoglenoid cyst size >2.2 cm, but not pain severity or muscle power, correlates with the positive finding of EMG for compressive suprascapular neuropathy. The GC size >2.2 cm can be a reference to decide the need of decompression surgery.

LEVEL OF EVIDENCE

IV, case series.

Successful Glenohumeral Shoulder Reduction With Combined Suprascapular and Axillary Nerve Block

BACKGROUND

Anterior glenohumeral dislocation is a common injury seen in the emergency department (ED) that sometimes requires procedural sedation for manual reduction. When compared with procedural sedation for dislocation reductions, peripheral nerve blocks provide similar patient satisfaction scores but have shorter ED length of stays. In this case report, we describe the first addition of an ultrasound-guided axillary nerve block to a suprascapular nerve block for reduction of an anterior shoulder dislocation in the ED.

CASE REPORT

A 34-year-old man presented to the ED with an acute left shoulder dislocation. The patient was a fit rock climber with developed muscular build and tone. An attempt to reduce the shoulder with peripheral analgesia was unsuccessful. A combined suprascapular and axillary nerve block was performed with 0.5% bupivacaine, allowing appropriate relaxation of the patient's musculature while providing excellent pain control. The shoulder was then successfully reduced without procedural sedation. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Procedural sedation for reduction of anterior shoulder dislocations is time consuming, resource intensive, and can be risky in some populations. The addition of an axillary nerve block to a suprascapular nerve block allows for more complete muscle relaxation to successfully reduce a shoulder dislocation without procedural sedation.

Ossification of Superior Transverse Scapular Ligament - Incidence, Embryology and Association with Suprascapular Neuropathy

Introduction

Suprascapular notch is present at superior border of scapula just medial to coracoid process. This is covered by superior transverse scapular ligament (STSL). Suprascapular nerve passes below this ligament while suprascapular vessels pass above it. STSL ossification is a rare finding with variable incidences in different population groups.

Materials and Methods

We observed 60 dry bony scapulae, 30 prosected formalin fixed upper limbs with scapula and 10 embalmed cadavers for the presence of ossified STSL.

Results

There were complete ossification of STSL in two dried bony specimens of sacpula.

Conclusion

Ossified STSL may be the causative factor for suprascapular neuropathy. The mainstay of management in cases of neuropathy or compression of suprascapular nerve is release of suprascapular ligament by either open or arthroscopic surgical approach. So, it is extremely important to know this type of variation to minimize any damage to related structure and plan the management accordingly.

Anatomical feasibility study of the infraspinatus muscle neurotization by lower subscapular nerve

OBJECTIVES

To investigate the anatomical feasibility of the infraspinatus branch of the suprascapular nerve (IB-SSN) reconstruction by lower subscapular nerve (LSN) transfer.

METHODS

The morphological study was performed on 18 adult human cadavers. The length of the distal stump of the IB-SSN, the length of the LSN available for reconstruction and diameter of both stumps were measured. The feasibility study of the LSN to IB-SSN transfer was performed.

RESULTS

The mean length of the IB-SSN to the end of its first branch was 40.9 mm (±4.6). Its mean diameter was 2.3 mm (±0.3). The mean length of the LSN stump, which was mobilized from its original course and transferred to reach the distal stump of the IB-SSN was 66.5 mm (±11.8). Its mean diameter was 2.1 mm (±0.3). The mean ratio between LSN and IB-SSN diameters was 0.9 (±0.1). The nerve transfer was feasible in 17 out of 18 cases (94.4%).

CONCLUSION

This study demonstrates that direct LSN to IB-SSN transfer is anatomically feasible in most cases in the adult population. It may be used in cases of complex scapular fractures resulting in severe suprascapular nerve injury.

Osseous suprascapular canal: rare variant that would hinder suprascapular nerve block and posterior surgical approach

PURPOSE

To report atypical anatomical variation of an osseous suprascapular canal, and to elaborate on its clinical significance as a potential anatomical factor that could obscure a direct posterior surgical approach and suprascapular nerve block.

METHODS

Osteological observational study of the scapula with emphasis on the suprascapular space. The pool of investigated sample size was collectively 768 specimens composed of 529 adult dry scapulae (240 paired, 289 un-paired), 54 children dry scapulae, 135 wet scapulae observed during cadaveric dissections, 47 retrospective 3D CT reconstructions, and 3 retrospective full sequence shoulder MRI. The two reported cases came from the 240 (120 skeleton) observed paired scapulae. Furthermore, the osseous suprascapular canal was examined by X-rays and its internal path was exposed by CT sections. A narrative review was conducted to investigate any relevant reports on the subject matter.

RESULTS

Two left dry bone scapulae with unilateral osseous suprascapular canal were found. The incidence of this atypical morphology of an osseous canal is probably five cases reported in three studies including this cases study.

CONCLUSIONS

The reported cases aid in explaining additional possible anatomical factors that could lead to below threshold anesthetic effect in posterior suprascapular nerve block procedures. Therefore, it is more practical to visualize the suprascapular canal by some imaging method before attempting to blindly access the suprascapular nerve in nerve block or posterior surgical approach due to the rare potential existence of an ossified barrier hindering the procedure.

LEVEL OF EVIDENCE

V Basic Science Research.

Anatomy and clinical application of suprascapular nerve to accessory nerve transfer

BACKGROUND

Loss of motor function in the trapezius muscle is one complication of radical neck dissection after cutting the accessory nerve (AN) during surgery. Nerve repair is an effective method to restore trapezius muscle function, and includes neurolysis, direct suture, and nerve grafting. The suprascapular nerve (SCN) and AN are next to each other in position. The function of the AN and SCN in shoulder elevation and abduction movement is synergistic. SCN might be considered by surgeons for AN reanimation.

AIM

To obtain anatomical and clinical data for partial suprascapular nerve-to-AN transfer.

METHODS

Ten sides of cadavers perfused with formalin were obtained from the Department of Human Anatomy, Histology and Embryology, Peking University Health Science Center. The SCN (n = 10) and AN (n = 10) were carefully dissected in the posterior triangle of the neck, and the trapezius muscle was dissected to fully display the accessory nerve. The length of the SCN from the origin of the brachial plexus (a point) to the scapular notch (b point) and the distance of the SCN from the origin point (a point) to the point (c point) where the AN entered the border of the trapezius muscle were measured. The length and branches of the AN in the trapezius muscle were measured. A female patient aged 55 years underwent surgery for partial SCN to AN transfer at Department of Oral and Maxillofacial Surgery, Peking University School and Hospital of Stomatology. The patient suffered from recurrent upper gingival cancer. Radical neck dissection was performed on the right side, and the right AN was removed at the intersection between the nerve and the posterior border of the SCM muscle. One-third of the diameter of the SCN was cut off, and combined epineurial and perineurial sutures were applied between the distal end of the cut-off fascicles of the SCN and the proximal end of the AN without tension. Both subjective and objective evaluations were performed before, three months after, and nine months after surgery. For the subjective evaluation, the questionnaire included the Neck Dissection Impairment Index (NDII) and the Constant Shoulder Scale. Electromyography was used for the objective examination. Data were analyzed using t tests with SPSS 19.0 software to determine the relationship between the length of the SCN and the linear distance. A P value of < 0.05 was considered as statistically significant.

RESULTS

The whole length of the AN in the trapezius muscle was 16.89 cm. The average numbers of branches distributed in the descending, horizontal and ascending portions were 3.8, 2.6 and 2.2, respectively. The diameter of the AN was 1.94 mm at the anterior border of the trapezius. The length of the suprascapular nerve from the origin of the brachial plexus to the scapular notch was longer than the distance of the suprascapular nerve from the origin point to the point where the accessory nerve entered the upper edge of the trapezius muscle. The amplitude of trapezius muscle electromyography indicated that both the horizontal and ascending portions of the trapezius muscle on the right side had better function than the left side nine months after surgery. The results showed that the right-sided supraspinatus and infraspinatus muscles did not lose more function than the left side.

CONCLUSION

Based on anatomical data and clinical application, partial suprascapular nerve-to-AN transfer could be achieved and may improve innervation of the affected trapezius muscle after radical neck dissection.

Ultrasound-guided continuous radiofrequency ablation of the suprascapular nerve for chronic shoulder pain secondary to osteoarthritis: a retrospective cohort study

OBJECTIVES

The objective of this study is to retrospectively evaluate the use of ultrasound-guided continuous radiofrequency (CRF) lesioning of the suprascapular nerve for treating chronic shoulder pain, due to osteoarthritis. We describe a modified distal and selective ablation technique in the spinoglenoid notch, with motor and sensory stimulation, which protects the motor branch of the nerve from ablation.

METHODS

A retrospective analysis was performed of patients, who underwent ultrasound-guided CRF lesioning of the suprascapular nerve from October 2013 to January 2020. During the procedure, the CRF electrode is placed in the spinoglenoid notch, at the distal suprascapular nerve capsular branch. Motor and sensory stimulations are used to confirm the position. CRF lesioning is applied up to three times, at 3 different points, for 1 min each time, at 80^° C.

RESULTS

In total, 127 first CRF suprascapular nerve lesioning procedures were performed on 101 patients with chronic shoulder pain secondary to osteoarthritis. One hundred nineteen diagnostic ultrasound-guided suprascapular nerve corticosteroid injections were performed prior to ablation. Mean pre-injection Visual Analogue Scale pain score (VAS) was 8.3, with post-injection VAS score of 4.4 at 24 h and 4.5 at 2 weeks. Mean pre-CRF lesioning VAS pain score was 7.7 with post-CRF lesioning VAS score of 4.4 at 24 h and 4.5 at 2 weeks.

CONCLUSIONS

Ultrasound-guided CRF lesioning of the suprascapular nerve in the spinoglenoid notch is a safe treatment for chronic osteoarthritic shoulder pain, with repeat treatments infrequently required. It is associated with significant improvement in VAS pain scores.

KEY POINTS

• Ultrasound-guided continuous radiofrequency lesioning of the suprascapular nerve in the spinoglenoid notch is a safe treatment for chronic shoulder pain in degenerative disease, with repeat treatments infrequently required. • The procedure is performed under ultrasound guidance, without the use of ionising radiation.

Possible donor nerves for axillary nerve reconstruction in dual neurotization for restoring shoulder abduction in brachial plexus injuries: a systematic review and meta-analysis

Restoring shoulder abduction is one of the main priorities in the surgical treatment of brachial plexus injuries. Double nerve transfer to the axillary nerve and suprascapular nerve is widely used and considered the best option. The most common donor nerve for the suprascapular nerve is the spinal accessory nerve. However, donor nerves for axillary nerve reconstructions vary and it is still unclear which donor nerve has the best outcome. The aim of this study was to perform a systematic review on reconstructions of suprascapular and axillary nerves and to perform a meta-analysis investigating the outcomes of different donor nerves on axillary nerve reconstructions. We conducted a systematic search of English literature from March 2001 to December 2020 following PRISMA guidelines. Two outcomes were assessed, abduction strength using the Medical Research Council (MRC) scale and range of motion (ROM). Twenty-two studies describing the use of donor nerves met the inclusion criteria for the systematic review. Donor nerves investigated included the radial nerve, intercostal nerves, medial pectoral nerve, ulnar nerve fascicle, median nerve fascicle and the lower subscapular nerve. Fifteen studies that investigated the radial and intercostal nerves met the inclusion criteria for a meta-analysis. We found no statistically significant difference between either of these nerves in the abduction strength according to MRC score (radial nerve 3.66 ± 1.02 vs intercostal nerves 3.48 ± 0.64, p = 0.086). However, the difference in ROM was statistically significant (radial nerve 106.33 ± 39.01 vs. intercostal nerve 80.42 ± 24.9, p < 0.001). Our findings support using a branch of the radial nerve for the triceps muscle as a donor for axillary nerve reconstruction when possible. Intercostal nerves can be used in cases of total brachial plexus injury or involvement of the C7 root or posterior fascicle. Other promising methods need to be studied more thoroughly in order to validate and compare their results with the more commonly used methods.

Anterior suprascapular nerve block versus interscalene brachial plexus block for arthroscopic shoulder surgery: a systematic review and meta-analysis of randomized controlled trials

This systematic review aimed to compare the analgesic effectiveness and complications rates for anterior suprascapular nerve blocks (ASSB) compared to interscalene brachial plexus blocks (ISB) for arthroscopic and outpatient shoulder surgery. Only randomized controlled trials (RCTs) comparing the ASSB versus ISB in the context of arthroscopic shoulder surgery were eligible for inclusion. The primary outcomes included pain scores (Numeric Rating Scale of 0 to 10) up to 24 h postoperatively and analgesic consumption. Secondary outcomes included block complications. Meta-analysis was performed using random-effects modeling and result certainty was determined using the GRADEpro tool. Six RCTs (709 patients) were included for analysis. ISB displayed a statistically significant reduction in pain scores by 0.40 (95%CI = 0.36 to 0.45; p < 0.00001) but not morphine equivalent consumption (mean difference = 0.74 mg; 95%CI = - 0.18 to 1.66 mg; I² = 60%; p = 0.11; moderate certainty) immediately in the postoperative care unit. Opioid consumption and pain scores at 6 to 24 h were not significantly different. There was no difference in respiratory events postblock. ASSB demonstrated a significantly lower incidence of Horner's syndrome (relative risk (RR) = 0.17; 95%CI = 0.08 to 0.39; p < 0.00001; high certainty), voice hoarseness (RR = 0.24; 95%CI = 0.10 to 0.57; p < 0.00001; high certainty) and impaired respiratory function (p < 0.00001). The ASSB could be considered an appropriate analgesic option for arthroscopic shoulder surgery with potentially fewer complications than the ISB.

Endoscopic/arthroscopic decompression of the suprascapular nerve at the spinoglenoid notch: indications and surgical technique

Suprascapular nerve compression at the spinoglenoid notch can lead to posterior shoulder pain, muscle weakness, and longstanding muscle atrophy of the infraspinatus. Although rare, it is most commonly seen in overhead athletes and laborers who perform repetitive overhead activities. Early diagnosis requires a thorough history and physical examination including imaging, diagnostic injections, and electromyography to avoid a missed diagnosis. While a course of nonoperative treatment is most often prescribed, early surgical intervention may be prudent to avoid irreversible damage especially if a space occupying lesion is present. This article will describe the history, physical examination findings, diagnostic workup, and our surgical technique for arthroscopic decompression of the suprascapular nerve at the spinoglenoid notch through a simple posterior approach avoiding the subacromial space.

The morphological stenosis pattern of the suprascapular notch is revealed yielding higher incidence in the discrete type and elucidating the inevitability of osteoplasty in horizontally oriented stenosis

PURPOSE

To identify the morphological patterns of suprascapular notch stenosis.

METHODS

Suprascapular notch space capacity was assessed by morphometric analysis of 333 dry scapulae. Suprascapular notch parameters-superior transverse distance, middle width, depth, medial border length and lateral border length-were measured. The probable suprascapular notch stenosis was referenced by (1) comparing each obtained parameter measurement to the range of the suprascapular nerve diameter, and (2) quantifying the reduced parameters. Finally, the morphological pattern was determined based on the collective reduction of the parameters and their alignments.

RESULTS

Five types of suprascapular notch based on depth to superior transverse distance ratio were identified and assessed. Type-I showed low incidence of stenosis (6/333) and low frequency within type (6/28) with potential risk of horizontal compression. Type-II showed relatively low incidence of stenosis (9/333) and low frequency within type (9/50) with undetermined pattern. Type-III showed relatively higher incidence of stenosis (47/333) but low frequency within type (47/158) with potential risk of vertical compression. Type-IV (foramen) showed low incidence of stenosis (6/333) and relatively lower frequency within type (6/26) with potential risk of encircled compression. Finally, type-V (discrete) showed relatively high incidence of stenosis (40/333) and high frequency within type (40/71) with potential risk of vertical compression. The suprascapular notch was found to be stenosed beyond its capacity to accommodate the suprascapular nerve in 49/333. Type-V is at most risk followed by Type-III.

CONCLUSIONS

Suprascapular notch stenosis takes three morphological patterns: horizontal, vertical or mixed. An osteoplasty of suprascapular notch margins may be required beside the common surgical approach of the superior transverse scapular ligamentectomy.

A meta-analysis on the anatomical variability of the brachial plexus: Part II - Branching of the supraclavicular part

INTRODUCTION

The anatomy of the supraclavicular part of the brachial plexus is highly variable, therefore the aim of this study was to perform a systematic review and meta-analysis of the various origins of the long thoracic, dorsal scapular, suprascapular and subclavian nerves.

MATERIALS AND METHODS

Major electronic databases were searched to identify all cadaveric studies investigating the morphology of the supraclavicular part of the brachial plexus. Data on the origins of these nerves were extracted and classified. A random effects meta-analysis was performed to state the pooled prevalence estimates.

RESULTS

A total of 26 studies, constituting a total of 1021 cases, were deemed eligible for inclusion into the meta-analysis. The usual origin of the long thoracic nerve from the C5, C6 and C7 roots was observed in 78.1% (95% CI 69.4-86.7%) of cases and 21.9% (95% CI 13.3-30.6%) had unusual origins. An accessory long thoracic nerve occurred in 0.3% (95% CI 0-0.7%) of cases. The overall prevalence of the dorsal scapular nerve arising from its usual origin the C5 root was found in 85.2% (95% CI 75.7-94.6%) of cases, while 14.8% (95% CI 5.4-24.3%) appeared abnormal. The suprascapular nerve emerged from its usual point on the superior trunk in 89.8% (95% CI 85.1-94.4%) of cases and in 10.2% (95% CI 5.6-14.9%) of cases had a variable origin. An accessory suprascapular nerve was present in 0.2% (95% CI 0-0.6%). Two possible sites of origin of the subclavian nerve were noted and the typical origin from the superior trunk was found in 98.3% (95% CI 96.3-100%) of cases and variable origin from the C5 root in 1.7% (95% CI 0-3.7%). All unusual origins of each nerve were much less common.

CONCLUSIONS

The nerves emerging from the supraclavicular part of the brachial plexus express a wide spectrum of potential origins. Based on their various origins, a new classification system for all the nerves belonging to the supraclavicular part was proposed. Knowledge of these variations and their prevalence data is important to prevent iatrogenic injuries and to state useful landmarks for interventions in the axilla.

The Middle Trunk Fascicle: A Simple, Effective Nerve Transfer for Suprascapular Nerve in Upper Brachial Plexus Injuries

A new nerve transfer option of using viable fascicle of the ipsilateral middle trunk for suprascapular nerve reconstruction is presented. The procedure was used in two patients with upper brachial plexus injury involving loss of shoulder abduction and external rotation. Clinical evaluation and nerve conduction studies in both patients confirmed axonopathy of C5, C6 roots and C5 root, respectively. The proximal root stumps were unavailable for nerve grafting due to a very proximal root level scarring. The middle trunk fascicle was dissected on its superior surface and transferred to the non-functional suprascapular nerve. After 24 months follow up full abduction and external rotation could be achieved in both the patients. It is a simple and easy option for transfer to a suprascapular nerve in upper brachial plexus injuries. It lies next only to the upper trunk and does not require any additional dissection time. Donor deficit was not observed in our two patients.

Comparison of clinical outcome of decompression of suprascapular nerve at spinoglenoid notch for patients with posterosuperior massive rotator cuff tears and suprascapular neuropathy

PURPOSE

In the present study, we aimed to determine whether decompression of suprascapular nerve (SSN) at the spinoglenoid notch could lead to a better functional outcome for the patients who underwent repairment of rotator cuff due to posterosupeior massive rotator cuff tear (MRCT) and suprascapular neuropathy.

METHODS

A total of 20 patients with posterosuperior MRCT and suprascapular neuropathy were analyzed in the present work. The preoperative magnetic resonance imaging (MRI) showed rotator cuff tear in supraspinatus and infraspinatus. All patients underwent arthroscopic rotator cuff repair. Patients were divided into two groups (group A: non-releasing, group B: releasing) according to whether the SSN at the spinoglenoid notch was decompressed. The modified University of California at Los Angeles shoulder rating scale (UCLA) and visual analog scale (VAS) questionnaire were adopted to assess the function of the affected shoulder preoperatively and 12 months after the operation. Electromyography (EMG) and nerve conduction study (NCS) were used to evaluate the nerve condition. Patients underwent MRI and EMG/NCS at 6 months after operation and last follow-up.

RESULTS

All patients were satisfied with the treatment. MRI showed that it was well-healed in 19 patients at 6 months after the operation. However, the fatty infiltration of supraspinatus and infraspinatus was not reversed. Only one patient in the non-releasing group showed the retear. The retear rate of group A and group B were 30% (3/10) and 20% (2/10) respectively at 12 months after the operation. One patient undergoing SSN decompression complained of discomfort in the infraspinatus area. His follow-up EMG after 6 months showed fibrillation potentials (1+) and positive sharp waves (1+) in the infraspinatus. The other patients' EMG results showed no abnormality. The postoperative UCLA and VAS scores were improved in both groups, and there was no significant difference in the follow-up outcomes between the two groups.

CONCLUSIONS

Patients with postersuperior MRCT and suprascapular neuropathy, decompression of suprascapular nerve at spinoglenoid notch didn't lead to a better functional outcome with the repairment of rotator cuff. Arthroscopic rotator cuff repair could reverse the suprascapular neuropathy.

LEVEL OF EVIDENCE

Level III.

Anatomical aspects of the selective infraspinatus muscle neurotization by spinal accessory nerve

The suprascapular nerve (SSN) is commonly reconstructed by spinal accessory nerve (SAN) transfer. However, reinnervation of its branch to the infraspinatus muscle (IB-SSN) is poor. Reconstruction of the SSN in cases of scapular fractures is frequently neglected in clinical practice. The morphological study was performed on 25 adult human cadavers. The course and the length of SSN of minimal diameter of 2 mm within the trapezius muscle, the length of the distal stump of IB-SSN to its branching point and the length of the SSN available for reconstructive procedure were measured. The feasibility study of the SAN - IB-SSN neurotization performed by using a bony canal under the spine of scapula was performed. The mean distance of the SAN from the spine was 8.5 cm (±0.88) at the point where it perforates the trapezius muscle and 4.49 cm (±0.72) at the most distal part of the nerve. The mean length of the intramuscular portion of the nerve was 14.74 cm (±1.99). It ran under a mean latero-medial angle of 15.54^° (±2.51). The mean distance between the medial end of the scapular spine and the SAN was 2.44 cm (± 0.64). The mean length of the IB-SSN was 3.6 cm (± 0.67). The mean length of the SAN stump which was mobilized from its original course and transferred to the infraspinous fossa to reach distal stump of the IB-SSN was 8.09 cm (±1.6). Direct SAN to IB-SSN transfer is anatomically feasible in the adult population.

Transfer of the rhomboid nerve for restoration of shoulder external rotation in partial brachial plexus palsy

Restoration of shoulder external rotation in partial brachial plexus palsies is a real challenge. The transfer of the spinal accessory nerve to the suprascapular nerve remains the gold standard. This transfer, however, cannot be always performed. Therefore, in these cases, we previously proposed the transfer of the rhomboid nerve to the suprascapular nerve through a posterior approach. The goal of the present study is to assess this technique through a short series. Eight male patients had a partial plexus palsy. Five patients had C5, C6 root injuries, two patients had C5, C6, C7 root injuries, and one patient had C5 to C8 root injuries. No patients had C5 or C6 root avulsions. In one patient, the spinal accessory nerve was injured and in seven patients, the proximal suprascapular nerve was not available. All patients underwent a transfer from the rhomboid nerve to the suprascapular nerve. Concerning shoulder elevation, transfers from the branch of the long head of the triceps or ulnar nerve fascicle were transferred to the axillary nerve. For elbow flexion, fascicles from the ulnar nerve, median nerve, or both were used. For elbow extension, three intercostal nerves in one patient and one fascicle from the ulnar nerve in two patients were transferred to the branch of the long head of the triceps. For wrist and finger extension, palliative surgery was proposed. All patients recovered external shoulder rotation (from 70-110º) and shoulder elevation (range, 80-140º). Active elbow flexion was coded M4 in seven patients and M3 in one patient. All patients recovered active elbow extension. The transfer of the rhomboid nerve to the suprascapular nerve is an efficient procedure for shoulder external rotation in partial brachial plexus palsies without C5 root avulsion. The results in terms of range-of-motion are, however, poorer than with the spinal accessory nerve. Therefore, this technique is appropriate if the spinal accessory nerve is injured or if the suprascapular nerve is not available in the cervical area. This technique must be associated with another transfer to the axillary nerve for shoulder elevation. The study of more patients will be necessary to confirm these results.

Applied anatomical study on suprascapular nerve protection in reverse total shoulder arthroplasty

BACKGROUND

This study aimed to investigate the three-dimensional (3D) anatomical relationship between the suprascapular nerve and scapula, and the method of protecting the suprascapular nerve in reverse total shoulder arthroplasty (RTSA) METHODS: In the present study, 12 fresh adult cadaver shoulder specimens were dissected. X-ray and computed tomography (CT) were used to investigate the 3D scapular and suprascapular nerve images.

RESULTS

The results revealed that the best fitting baseplate diameter was 24.73 ± 1.56 mm. Furthermore, the baseplate diameter correlated with the glenoid cavity width. After the osteotomy, a simulated screw placement on the baseplate was performed. The dangerous area for the posterior screw placement was at the angle between the upper edge and transverse axis exceeding 38° and between the lower edge and transverse axis exceeding 76°. The distance between the nearest point of the nerve and osteotomy plane was 15.38 ± 2.02 mm, and the angle between the projection point of the nearest point and transverse axis was 27.33 ± 7.96°, which was the dangerous area for retractor placement. The suitable angle between the superior screw and longitudinal axis was 21.67 ± 13.27°, and the suitable superior screw length was 34.66 ± 2.41 mm.

CONCLUSION

In RTSA, the baseplate size correlates with the glenoid cavity width. The relationship between the screw and suprascapular nerve and retractor placement position should be carefully considered to avoid damaging the suprascapular nerve.

"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.

Comparing Three Modalities of Treatment for Frozen Shoulder: A Prospective, Double-Blinded, Randomized Control Trial

PURPOSE

To compare the effects of three modalities of pain management i.e. SSNB (suprascapular nerve block) with NIR (non invasive rehabilitation), IAI (intra articular injection) with NIR and, NIR alone in idiopathic frozen shoulder patients.

METHODS

A double blinded randomized clinical trial was conducted. 60 cases of idiopathic frozen shoulder were selected and randomly divided into three treatment groups; group 1: NIR, group 2: NIR + SSNB, group 3: NIR +IAI. Range of motion, pain score and disability (SPADI: shoulder pain and disability index) score were evaluated pre-treatment and at 12 weeks follow up.

RESULTS

All three groups were homogenous and comparable regarding their age, sex ratio, pretreatment pain score, disability score and range of motion. There was significant improvement (p < 0.05) post treatment in all three groups with respect to pain score, disability score and range of motion. SSNB with NIR group patients demonstrated better improvement in all parameters examined, which was statistically significant in pain score, disability score and internal rotation but was statistically equivalent for total range of motion and external rotation as compared to shoulder injection group.

CONCLUSION

SSNB in combination with non invasive rehabilitation is an effective and safe mode of treatment for idiopathic frozen shoulder. Present study also proves that SSNB with NIR is a more effective mode of treatment for idiopathic frozen shoulder as compared to NIR alone or in combination with IAI.Level of evidence: Level 1.

Bilateral Suprascapular Nerve Injury and Novel Technique of Nerve Transfers for Restoration of External Rotation: Case Report

BACKGROUND

Complex brachial plexus and peripheral nerve injuries can be challenging to evaluate and treat, especially in the face of novel pathology.

OBJECTIVE

To describe the diagnosis of bilateral suprascapular nerve injury, the unique surgical anatomy, and the novel use of a distal nerve transfer to re-establish external rotation. To the best of our knowledge, bilateral suprascapular nerve injury has not previously been reported.

METHODS

The authors describe the physical examination and electrodiagnostic and imaging work-up for elucidating complex injury patterns and present a procedure for reinnervating the infraspinatus muscle.

RESULTS

A 48-yr-old man presented with profound, right-sided, partial brachial plexus injury incurred 5 mo earlier in a motorcycle accident. Imaging demonstrated atrophy and severe edema within the bilateral supraspinatus and infraspinatus muscles. Needle electromyography depicted no motor units and insertional activities in bilateral infraspinatus muscles, consistent with bilateral suprascapular nerve injury. Along with brachial plexus repair, the patient underwent transfer of a distal branch of the spinal accessory nerve to the inferolateral branch of the suprascapular nerve to the infraspinatus muscle. At 16 mo, he had recovered strong restoration of shoulder external rotation.

CONCLUSION

Systematic evaluation can assist in defining complex pathology, particularly with previously unreported types. In this case, predominant injury was inflicted upon the branch innervating the infraspinatus. Highly focal nerve transfers can achieve substantial restoration of external rotation.

Infraspinatus muscle palsy involving suprascapular nerve, brachial plexus or cervical roots related to inflammatory or mechanical causes: Experience of 114 cases

OBJECTIVES

To report a large series of neurogenic infraspinatus muscle (ISM) palsy, in order to improve knowledge of diagnosis, diverse etiologies and care management.

METHODS

Clinical and electrodiagnostic (EDX) data for 114 cases of ISM palsy were collected over a 21-year period. Cases were attributed to 4 clinical conditions: (1) isolated suprascapular nerve mononeuropathy (n=48), (2) multiple mononeuropathies (n=33), (3) plexus lesions (n=17), and (4) cervical radiculopathy (n=16). These were related to 2 mechanisms: inflammatory (dysimmune) and mechanical.

RESULTS

Group 1 cases were younger, had the most severe ISM palsies, were mostly related to inflammatory lesions (81%) such as neuralgic amyotrophy (NA), and frequently had delayed diagnosis because disability was mild. Group 2 cases were all related to inflammatory lesions and had slightly less severe ISM palsies that were frequently hidden by winged scapula. In groups 3 and 4, ISM palsies were milder and all cases were related to mechanical lesions such as brachial plexus trauma or C4-C5-C6 radiculopathy. In these cases, deltoid and ISM palsies were equal in frequency and severity whereas biceps brachii impairment was less frequent and much milder. Deltoid palsy frequently appeared predominant as compared with ISM palsy, because upper limb elevation palsy was more disabling than external rotation palsy.

CONCLUSIONS

ISM palsy is a rare condition, often under-diagnosed and misidentified. The 4 main conditions of ISM palsy may be recognized by careful clinical, EDX and other examinations when necessary. Analysis of the present series highlights some clinical and EDX points that should help non-specialist and even specialist clinicians who are faced with this rare condition, to distinguish mechanical and inflammatory causes, and thus adapt patient management accordingly.

Hourglass-like constriction neuropathy of the suprascapular nerve detected by high-resolution magnetic resonance neurography: report of three patients

Hourglass-like constriction neuropathy is a neurological condition caused by non-traumatic, non-compressive fascicular constrictions of one or more individual peripheral nerves. Based on clinical manifestations, it is very difficult to differentiate hourglass-like constriction neuropathy from idiopathic neuralgic amyotrophy. Focal hourglass-like constriction neuropathy may be erroneously diagnosed as idiopathic neuralgic amyotrophy. Previous studies demonstrated hourglass-like constrictions of peripheral nerves in the surgical exploration of patients diagnosed with idiopathic neuralgic amyotrophy. Recently, high-resolution ultrasound or magnetic resonance neurography (MRN) have been introduced to detect focal hourglass-like constrictions of peripheral nerves in spontaneous nerve palsy. We present a series of three cases in which the suprascapular nerve was affected by hourglass-like constrictions, which were visualized by high-solution MRN, including a nerve-selective morphological MR pulse sequence with strong fat- and water-signal suppression.

Comparative study of single and dual nerve transfers for repairing shoulder abduction

OBJECTIVE

The purpose of this study was to compare the effects of single and dual nerve transfer for the repair of shoulder abduction in patients with upper or upper and middle trunk root avulsion.

METHODS

We carried out a retrospective analysis of 20 patients with C5-C6 or C5-C7 root avulsion treated by nerve transfer in our hospital. The patients were divided into two groups according to the different operation methods. In group A, ten patients had transferred the spinal accessory nerve to the suprascapular nerve. Ten patients in group B underwent dual nerve transfer to reconstruct shoulder abduction, including the spinal accessory nerve transfer to the suprascapular nerve and two intercostal nerves or the long head of triceps nerve branch transfer to the anterior branch of the axillary nerve. There was no difference in age, preoperative interval, follow-up time, and injury type between the two groups. We used shoulder abduction strength, shoulder abduction angle, and Samardzic's shoulder joint evaluation standard as the postoperative evaluation index. Shoulder abductor muscle strength equals or above M3 was considered to be an effective recovery.

RESULTS

Of the 20 cases, 15 obtained equals or more M3 of shoulder abduction strength, and the overall effective rate was 75%. The effective rate of shoulder abduction power in group A was 60% (6/10) while group B was 90% (9/10); however, the difference was not statistically significant (p > 0.05). The average shoulder abduction angle was 55° (SD = 19.29) in group A and 77° (SD = 20.44) in group B; the angle was significantly better in group B than that in group A (p < 0.05). Based on Samardzic's standard, the excellent and good rate of group A was 90% and in group B was 50%. The difference was statistically significant (p < 0.05).

CONCLUSION

For patients with nerve root avulsion of C5-C6 or C5-C7, repairing suprascapular nerve and axillary nerve at the same time is more effective than repairing suprascapular nerve alone in terms of shoulder abduction angle and excellent rate of functional recovery of the shoulder joint. Therefore, we recommend the repair of the suprascapular nerve and the axillary nerve simultaneously if conditions permit.

Force perception at the shoulder after a unilateral suprascapular nerve block

There are two key sources of information that can be used to match forces-the centrally generated sense of effort and afferent signals from mechanical receptors located in peripheral tissues. There is currently no consensus on which source of information is more important for matching forces. The corollary discharge hypothesis argues that subjects match forces using the centrally generated sense of effort. The purpose of this study was to investigate force matching at the shoulder before and after a suprascapular nerve block. The nerve block creates a sensory and muscle force mismatch between sides when matching loads. The torque matching accuracy did not change after the nerve block was administered. Directionally, the torque error was in the direction proposed by the corollary discharge hypothesis. However, the mismatch between deltoid EMG was substantially greater compared to the changes in the torque matching error after the block. The results support that sensory information is used during force matching tasks. However, since the nerve block also created a sensory disruption between sides, it is not clear how sensory information is reweighted following the nerve block and a role for sense of effort is still implicated.

Unusual Case of a Volleyball Athlete Presenting with Posterior Shoulder Pain and Infraspinatus Muscle Wasting

Introduction:

Entrapment of the suprascapular nerve is an uncommon but important differential in patients who present with posterior shoulder pain. Frequently misdiagnosed as rotator cuff or cervical disc disease, this increasingly recognized entity can result from traction-related or compression-related etiology. Two sites of compression include the suprascapular and spinoglenoid notches with the latter less commonly encountered.

Case Report:

In our study, we describe a case of arthroscopic decompression of suprascapular nerve entrapment at the spinoglenoid notch due to hypertrophied spinoglenoid ligament using an improvised arthroscopic technique.

Conclusion:

Spinoglenoid notch compression of the suprascapular nerve is an important cause of posterior shoulder pain with infraspinatus wasting. A clear understanding of the nerve anatomy and the common site of compression allow for accurate diagnosis. The modified arthroscopic technique described is easily reproducible and provides good visualization of the anatomy, allowing adequate and safe decompression of the suprascapular nerve.

Efficacy of ultrasound-guided suprascapular nerve block treatment in patients with painful hemiplegic shoulder

OBJECTIVE

The aim of this study was to evaluate the efficacy of ultrasound-guided suprascapular block treatment in patients with painful hemiplegic shoulder whose pain was not reduced after conservative treatment.

DESIGN

The patients were those whose hemiplegic shoulder pain was not reduced by standard conservative treatment prior to discharge. The study group (n = 21) included patients who had undergone an ultrasound-guided suprascapular nerve block (SSNB). The control group (n = 21) were patients who had not undergone SSNB. Both groups undertook home exercise programs. All patients were evaluated at 1 week and 1 and 3 months after the discharge. Evaluations included shoulder range of motion (ROM), Visual Analog Scale (VAS) for pain, EQ-5D-3L for quality of life, the Modified Ashworth Scale (MAS), and Brunnstrom staging.

RESULTS

The shoulder ROM significantly increased in the SSNB group at 1-3 months, when compared with the baseline value. The shoulder ROM significantly decreased (p ˂ 0.05) in the control group at 1-3 months, when compared with the baseline value. The pain VAS and EQ-5D-3L scores significantly decreased (p ˂ 0.05) after treatment in the follow-ups at 1 month in the SSNB group. The control group showed no change from the baseline scores (p ˃ 0.05). The MAS scores and Brunnstrom staging did not differ between the two groups.

CONCLUSION

The ultrasound-guided SSNB is a safe and more effective treatment than conservative treatment for painful hemiplegic shoulder. Further studies are needed to compare ultrasound-guided and non-guided suprascapular blocks as treatments for hemiplegic shoulder pain.

Monocortical fixation of the coracoid in the Latarjet procedure is significantly weaker than bicortical fixation

PURPOSE

A crucial step of the Latarjet procedure is the fixation of the coracoid process onto the glenoid. Multiple problems associated with the fixation have been described, including lesions of the suprascapular nerve due to prominence of the screw or bicortical drilling. The purpose of the present study was to evaluate whether monocortical fixation, without perforating the posterior glenoid cortex, would provide sufficient graft stability.

METHODS

Coracoid transfer was performed in 14 scapula models (Sawbones^®, Composite Scapula, 4th generation). Two groups were assigned: in one group, fixation was achieved with two screws that did not perforate the posterior cortex of the glenoid neck (monocortical fixation), in the other group, fixation was achieved with perforation of the posterior cortex (bicortical fixation). The ultimate failure load and mode of failure were evaluated biomechanically.

RESULTS

Monocortical fixation was a significantly weaker construct than bicortical fixation (median failure load 221 N, interquartile range 211-297 vs. median failure load 423 N, interquartile range 273-497; p = 0.017). Failure was either due to a pullout of the screws from the socket or a fracture of the glenoid. There was no significant difference in the mode of failure between the two groups (n.s.).

CONCLUSION

Monocortical fixation was significantly weaker than bicortical fixation. However, bicortical drilling and overly long screws may jeopardize the suprascapular nerve. Thus, anatomic knowledge about the safe zone at the posterior rim of the glenoid is crucial. Until further research has evaluated, if the inferior stability is clinically relevant, clinicians should be cautious to use a monocortical fixation technique for the coracoid graft.

Risk of neurological injury in posterior bone block surgery for recurrent glenohumeral instability: a cadaveric study

INTRODUCTION

Recurrent posterior glenohumeral instability poses a challenge for treatment. Bone block procedures have been advocated in cases where a bony defect is present. However, these techniques are not free of complications due to the proximity of neurovascular structures. The aim of this study is to measure the distance to the axillary and suprascapular nerves at the different steps of the procedure.

MATERIALS AND METHODS

Ten frozen human cadavers were used. The bone graft was prepared and placed on the posterior aspect of the glenoid, where it was fixed with two K-wires in different positions: parallel to the articular surface and with 20° of medial angulation. The distance from the entry and exit points of the K-wires to the axillary and suprascapular nerves was measured.

RESULTS

At the exit point, mean distance from the superior K-wire to the axillary nerve was 4.4 mm in the neutral position and 14.4 mm when medially angulated (p = 0.01) and 2.6 mm and 11.5 mm, respectively, for the inferior K-wire (p < 0.01). No differences were found at the entry point (p = 0.7 and p = 0.3). For the suprascapular nerve, mean distance to the entry point of the superior K-wire was significantly greater when it was inserted with 20° of medial angulation than when placed in neutral position (p = 0.04). No differences were found for the inferior K-wire (p = 0.35).

CONCLUSION

Posterior bone block surgery should be performed taking into consideration the possibility of axillary nerve injury anteriorly at the exit point of the K-wires. Wire and screw insertion parallel to the glenoid articular surface may reduce the risk, while increased wire or screw medial angulation with respect to the glenoid surface may heighten risk.

LEVEL OF EVIDENCE

Not applicable (cadaveric study).

Hourglass-like constriction of the suprascapular nerve: a contraindication for minimally invasive surgery

BACKGROUND

Suprascapular nerve (SSN) entrapment is usually ascribed to static or dynamic compression. When no cause of compression is found, SSN entrapment is defined as idiopathic. Focal hourglass-like constriction (H-LC) of the SSN that results in muscle paralysis represents an unusual condition that may be misinterpreted and erroneously diagnosed as SSN entrapment or as neuralgic amyotrophy.

METHODS

With the aim of finding clinical and surgical clues that could differentiate the traditional form of idiopathic SSN entrapment from the rare H-LC, a series of 6 cases of SSN palsy caused by H-LC is presented.

RESULTS

All but 1 supraspinatus muscle recovered M5 muscle strength. The Constant shoulder score was excellent in 3 patients, good in 1, fair in 1, and poor in 1.

DISCUSSION

If a diagnosis is not made in time, H-LC may evolve from mild to severe nerve torsion that may require a shift in surgical procedure from epineurotomy and external neurolysis to focal resection and suture. If an incorrect therapy is chosen, the chance of recovery might be definitively compromised with the persistence of muscle palsy. Conversely, when SSN palsy persists despite notch decompression, especially when it is performed with a limited open approach or arthroscopically, concerns about the real etiology and location of nerve compression responsible for the nerve palsy may arise.

CONCLUSION

When approaching SSN pathology, H-LC should be considered as a potential cause of nerve palsy, as it may represent a contraindication for a limited open approach or arthroscopic decompression.

The contribution of the supraspinatus muscle at sub-maximal contractions

During maximum effort, the supraspinatus muscle contributes approximately 50% of the torque need to elevate the arm, but this has not been examined at sub-maximal levels. The purpose of this study was to determine the contribution of the supraspinatus muscle to shoulder elevation at sub-maximal levels. Seven healthy subjects (four males, three females) performed isometric ramp contractions at the shoulder. Middle deltoid electromyography (EMG) and force applied at the wrist were collected before and after a suprascapular nerve block. For the same level of deltoid EMG, less external force will be measured after the nerve block as the supraspinatus muscle no longer contributes. The difference between the EMG/force curve was the contribution of the supraspinatus muscle. The supraspinatus contributed 40%, 95% CI [32%-48%], to shoulder elevation. The effect of angle (p = .67) and % maximal voluntary contraction (p = .13) on supraspinatus contribution were not significant. The maximum is slightly less than reported in a previous suprascapular nerve block study using maximal contractions. The results from this study can be used to assess supraspinatus contribution in rotator cuff tears, after rehabilitation interventions, and as a restraint in computation modelling.

Intraneural cyst of the supraescapular nerve: Atypical cause of peripheral nerve entrapment syndrome. Case report and literature review

OBJECTIVE

Intraneural cysts are benign lesions located within the epineurium of some peripheral nerves and their aetiopathogenesis is controversial. Most are located at the level of the lower limbs. In the upper limbs, the most frequently affected nerve is the ulnar nerve. Suprascapular nerve entrapment syndrome due to the formation of an intraneural cyst is rare. In this article, we show a new case and perform a literature review of intraneural cysts located in the suprascapular nerve.

METHODS

We present a 49-year-old woman with pain in the lateral shoulder region of several months' evolution. A brachial plexus MR showed a tumour of approximately 2×1.5cm, with a cystic appearance, in relation to the upper trunk of the right brachial plexus.

RESULTS

We used a supra-infraclavicular approach. The cystic tumour affected the suprascapular nerve. After locating a zone on the surface without nervous fascicles, we performed a partial resection of the capsule and emptying of the cyst, with a xanthochromic gelatinous content. The anatomopathological examination confirmed the diagnosis of intraneural cyst.

CONCLUSION

The suprascapular nerve is a mixed nerve, coming from the upper trunk. It provides the motor branches to the supraspinatus and infraspinatus muscle. Compression of the suprascapular nerve leads to atrophy of these muscles. This entity is one of the differential diagnoses in a patient with pain irradiating to the shoulder, and its correct treatment often results in complete remission of symptoms.

A new approach for endoscopic neurolysis of the suprascapular nerve at the spinoglenoid notch: A preliminary cadaver study

The suprascapular nerve (SSN) can become compressed at its 2 scapular attachments: the suprascapular and the spinoglenoid notch. The objective of this study was to describe a new arthroscopic approach for SSN neurolysis at the spinoglenoid notch. Ten cadaver shoulders were used. Two were dissected to simulate the "classical" arthroscopic approach and to help in the creation of a new "direct medial retrospinal" approach. Eight other shoulders were used to validate this new approach, with control of the whole juxta-glenoid course of the SSN as criterion of success. The retrospinal posterior approach allowed the entire juxta-glenoid segment of the SSN to be explored in 6 cases out of 8. One exploration was incomplete, another not feasible. SSN neurolysis at the spinoglenoid notch was feasible in cadavers on a retrospinal approach.

Drilling through lateral transmuscular portal lowers the risk of suprascapular nerve injury during arthroscopic SLAP repair

PURPOSE

The aim of our study was to evaluate the risk of medial glenoid perforation and possible injury to suprascapular nerve during arthroscopic SLAP repair using lateral transmuscular portal.

METHODS

Ten cadaveric shoulder girdles were isolated and drilled at superior glenoid rim from both anterior-superior portal (1 o'clock) and lateral transmuscular portal (12 o'clock) for SLAP repairs. Drill hole depth was determined by the manufacturer's drill stop (20 mm), and any subsequent drill perforations through the medial bony surface of the glenoid were directly confirmed by dissection. The bone tunnel depth and subsequent distance to the suprascapular nerve, scapular height and width, were compared for investigated locations.

RESULTS

Four perforations out of ten (40 %) occurred through anterior-superior portal with one associated nerve injury. One perforation out of ten (10 %) occurred through lateral transmuscular portal without any nerve injury. The mean depth was calculated as 17.6 mm (SD 3) for anterior-superior portal and 26.5 mm (SD 3.6) for lateral transmuscular portal (P < 0.001).

CONCLUSIONS

It is anatomically possible that suprascapular nerve could sustain iatrogenic injury during labral anchor placement during SLAP repair. However, lateral transmuscular portal at 12 o'clock drill entry location has lower risk of suprascapular nerve injury compared with anterior-superior portal at 1 o'clock drill entry location.

The risk of suprascapular and axillary nerve injury in reverse total shoulder arthroplasty: An anatomic study

PURPOSE

Implantation of a reverse total shoulder arthroplasty (rTSA) places the axillary and suprascapular nerves at risk. The aim of this anatomic study was to digitally analyse the location of these nerves in relation to bony landmarks in order to predict their path and thereby help to reduce the risk of neurological complications during the procedure.

METHODS

A total of 22 human cadaveric shoulder specimens were used in this study. The axillary and suprascapular nerves were dissected, and radiopaque threads were sutured onto the nerves without mobilizing the nerves from their native paths. Then, 3D X-ray scans of the specimens were performed, and the distance of the nerves to bony landmarks at the humerus and the glenoid were measured.

RESULTS

The distance of the inferior glenoid rim to the axillary nerve averaged 13.6mm (5.8-27.0mm, ±5.1mm). In the anteroposterior direction, the distance between the axillary nerve and the humeral metaphysis averaged 8.1mm (0.6-21.3mm, ±6.5mm). The distance of the glenoid centre to the suprascapular nerve passing point under the transverse scapular ligament measured 28.4mm (18.9-35.1mm, ±3.8mm) in the mediolateral direction and 10.8mm (-4.8 to 25.3mm, ±6.1mm) in the anteroposterior direction. The distance to the spinoglenoid notch was 16.6mm (11.1-24.9mm, ±3.4mm) in the mediolateral direction and -11.8mm posterior (-19.3 to -4.7mm, ±4.7mm) in the anteroposterior direction.

CONCLUSIONS

Implantation of rTSA components endangers the axillary nerve because of its proximity to the humeral metaphysis and the inferior glenoid rim. Posterior and superior drilling and extraosseous screw placement during glenoid baseplate implantation in rTSA place the suprascapular nerve at risk, with safe zones to the nerve passing the spinoglenoid notch of 11mm and to the suprascapular notch of 19mm.

Glenoid morphology and the safe zone for protecting the suprascapular nerve during baseplate fixation in reverse shoulder arthroplasty

PURPOSE

The purpose of this study was to investigate glenoid morphology and define the safe zone for protecting the suprascapular nerve baseplate screw during baseplate fixation in reverse shoulder arthroplasty (RSA) in a Chinese population.

METHODS

Shoulder computed tomography (CT) scans from 56 subjects were retrospectively reviewed. Three-dimensional (3D) reconstruction was performed using Mimics software, and corresponding bony references were used to evaluate glenoid morphology. To standardize evaluation, the coronal scapular plane was defined. Safe fixation distances and screw placements were investigated by constructing a simulated cutting plane of the baseplate during RSA.

RESULTS

Mean glenoid height was 35.83 ± 2.95 mm, and width was 27.32 ± 2.78 mm, with significant sexual dimorphism (p < 0.01). According to the cutting plane morphology, the average baseplate radius was 13.84 ± 1.34 mm. The distances from the suprascapular notch and from two bony reference points at the base of the scapular spine to the cutting plane were 30.27 ± 2.77 mm, 18.39 ± 1.67 mm and 16.52 ± 1.52 mm, respectively, with a gender-related difference. Based on the clock face indication system, the danger zone caused by the suprascapular nerve projection was oriented between the two o'clock and eight o'clock positions in reference to the right shoulder.

CONCLUSIONS

Glenoid size and the safe zone for screw fixation during RSA were characterized in a Chinese population. Careful consideration of baseplate fixation and avoidance of suprascapular nerve injury are important for improved clinical outcome.

Glenoid morphology in light of anatomical and reverse total shoulder arthroplasty: a dissection- and 3D-CT-based study in male and female body donors

Background

Placement of the glenoid baseplate is of paramount importance for the outcome of anatomical and reverse total shoulder arthroplasty. However, the database around glenoid size is poor, particularly regarding small scapulae, for example, in women and smaller individuals, and is derived from different methodological approaches. In this multimodality cadaver study, we systematically examined the glenoid using morphological and 3D-CT measurements.

Methods

Measurements of the glenoid and drill hole tunnel length for superior baseplate screw placement were recorded to define size of the glenoid and the distance to the scapular notch on cadaveric specimens. Glenoid angles were determined on both, 3D-CT-scans of the thoraxes using the Friedman method and on subsequently isolated scapulae from 18 male and female donors (average 84 years, range 60–98 years).

Results

Mean glenoid height was 36.6 mm ± 3.6, and width 27.8 mm ± 3.1 with a significant sex dimorphism (p ≤ 0.001): in males, glenoid height 39.5 mm ± 3.5, and width 30.3 mm ± 3.3, and in females, glenoid height 34.8 mm ± 2.2, and width 26.2 mm ± 1.6. The average distance from the superior screw entry to its exit in the scapular notch measured by calliper was 27.2 mm ± 6.0 with a sex difference: in males, 29.4 mm ± 5.7, and in females, 25.8 mm ± 5.9 mm with a minimum recorded distance of 15 mm. Measured by CT, the mean inclination angle for male and female donors combined was 13.0° ± 7.0, and the ante-/retroversion angle −1.0° ± 4.0°.

Conclusion

This study is one of the first to combine dissection, including drill holes, with anatomical measurements and radiological data. In some women and smaller individuals, smaller baseplates should be selected. The published safe zone of 20 mm is generally feasible for superior screw placement, however, in small patients this distance may be substantially shorter than expected and start as of 13 and 15 mm, respectively. No correlation between glenoid height or width with the length of our drilling canal towards the scapular notch was found. Preoperative CT-based treatment planning to determine version and inclination angles is recommended.

Rhomboid nerve transfer to the suprascapular nerve for shoulder reanimation in brachial plexus palsy: A clinical report

Recovery of shoulder function is a real challenge in cases of partial brachial plexus palsy. Currently, in C5-C6 root injuries, transfer of the long head of the triceps brachii branch is done to revive the deltoid muscle. Spinal accessory nerve transfer is typically used for reanimation of the suprascapular nerve. We propose an alternative technique in which the nerve of the rhomboid muscles is transferred to the suprascapular nerve. A 33-year-old male patient with a C5-C6 brachial plexus injury with shoulder and elbow flexion palsy underwent surgery 7 months after the injury. The rhomboid nerve was transferred to the suprascapular nerve and the long head of the triceps brachii branch to the axillary nerve for shoulder reanimation. A double transfer of fascicles was performed, from the ulnar and median nerves to the biceps brachii branch and brachialis branch, respectively, for elbow flexion. At 14 months' follow-up, elbow flexion was rated M4. Shoulder elevation was 85 degrees and rated M4, and external rotation was 80 degrees and rated M4. After performing a cadaver study showing that transfer of the rhomboid nerve to the suprascapular nerve is technically possible, here we report and discuss the clinical outcomes of this new transfer technique.

Long-term clinical outcomes of spinal accessory nerve transfer to the suprascapular nerve in patients with brachial plexus palsy

BACKGROUND

For the reconstruction of brachial plexus lesions, restoration of elbow flexion and shoulder function is fundamental and is achieved by dual nerve transfers. Shoulder stabilization and movement are crucial in freedom of motion of the upper extremity. In patients with C5-C6 brachial plexus injury, spinal accessory nerve transfer to the suprascapular nerve and a fascicle of ulnar nerve to musculocutaneous nerve (dual nerve transfer) are carried out for restoration of shoulder abduction and elbow flexion, respectively. In the present study, we evaluated the long-term clinical outcomes of spinal accessory nerve transfer to the suprascapular nerve for restoration of shoulder abduction in patients with brachial plexus palsy undergoing a dual nerve transfer.

PATIENTS AND METHODS

In the present retrospective review, 22 consecutive subjects with upper brachial plexus palsy were assessed. All of the subjects underwent spinal accessory nerve transfer to the suprascapular nerve and a dual nerve transfer from the ulnar nerve to the biceps branch and from the median nerve to the brachialis branch of the musculocutaneous nerve simultaneously. All of the subjects were followed up for 18 to 24 months (average, 21.7 months) for assessing the recovery of the shoulder abduction and motor function.

RESULTS

Spinal accessory nerve transfer to the suprascapular nerve showed a motor function recovery of M3 and M4 in 13.6 and 63.6% of the subjects, respectively. However, 22.7 % of the subjects remained with a motor function of M2. The mean of shoulder abduction reached 55.55 ± 9.95° (range, 40-72°). Altogether, good functional results regained in 17 out of 22 the subjects (77.2 %). Linear regression analysis showed that advanced age was a predictor of low motor functional grade.

CONCLUSIONS

The evidence from the present study suggests that transferring spinal accessory nerve to the suprascapular nerve for restoring shoulder abduction is an effective and reliable treatment with high success rate in patients with brachial plexus palsy, especially in young patients.