Isolated paralysis of the serratus anterior muscle: surgical release of the distal segment of the long thoracic nerve in 52 patients

Neurolysis of the Long Thoracic Nerve for Scapular Winging due to Isolated Serratus Anterior Palsy: Early and Midterm Results in 29 Patients

Objective

This study aimed to report our surgical outcomes of thoracic long thoracic nerve (LTN) decompression in patients with isolated LTN palsy, using a clinical scoring system designed to facilitate the grading of scapular winging severity.

Methods

This was a retrospective review of patients who had undergone decompression and neurolysis of the LTN for scapular winging. Each patient underwent needle electromyography of the serratus anterior for confirmation of diagnosis and were refractory to a minimum of 6 months of nonoperative management. Preoperatively and at final follow-up, shoulder range of motion and the Wrightington Winging Score (WWS) was used to objectively grade the dynamic and static components of winging.

Results

Between 2014 and 2020, 29 patients who underwent thoracic neurolysis for scapular winging were analyzed. These were 16 males and 13 females with a mean age of 37 years. The injury mechanism was due to trauma in 19 cases and neuralgic amyotrophy in 10. The median duration between winging onset and surgery was 30 months. There were significant improvements in mean active shoulder abduction and forward flexion. Winging was noticeably improved in 22 patients. At presentation, the median WWS was 3, which improved to 1 at final follow-up.

Conclusion

In patients with isolated LTN palsy causing persistent scapular winging which is not responsive to conservative treatment, neurolysis of the thoracic portion of the LTN can be considered.

Level of Evidence

IV.

Long Thoracic Nerve Palsy: When Is Decompression Indicated

Scapular winging due to long thoracic nerve palsy can occur through traumatic injuries and nontraumatic events. The traditional view is that most patients will achieve spontaneous recovery within 2 years of winging onset. However, there is evidence that points to a less clear-cut natural history, with residual winging, muscle weakness, and fatigability being exhibited in a significant percentage of patients. Reports from proponents of a more proactive approach have shown that the surgical decompression of the long thoracic nerve beyond 12 months, through thoracic, supraclavicular, or combined approaches, can yield satisfactory results. This review examines our current understanding of long thoracic nerve palsy and explores the varying treatment strategies with their reported outcomes.

Scapular winging due to rhomboid muscle paralysis: clinical assessment of 4 cases and anatomic study of the dorsal scapular nerve

BACKGROUND

A rare cause of scapular winging is rhomboid muscle paralysis secondary to dorsal scapular nerve (DSN) neuropathy. This paralysis causes winging of the medial border of the scapula with lateral rotation of its inferior angle. We report a series of 4 clinical cases of isolated DSN compression and the results of a specific rehabilitation protocol.

METHODS

A continuous clinical series of 4 patients with isolated rhomboid muscle deficiency was analyzed. Two patients were men and 2 were women, with a mean age of 40 years (range, 33-51 years). Three patients were right-handed and 1 was left-handed. Scapular winging always affected the dominant side. Two patients had occupations involving heavy physical work. The sports practiced involved exertion of the arms (dancing, boxing, gymnastics, muscle strengthening). A specific rehabilitation protocol was offered to the patients. In addition, 6 fresh cadaver dissections were performed to reveal possible DSN compression. Potential areas of compression were identified, in particular when the arm was raised.

RESULTS

The 4 patients presented with isolated DSN neuropathy were confirmed by electroneuromyographic testing. Total correction of scapular winging was not obtained in any patient. Three patients experienced residual pain with a neuropathic pain by the questionnaire for a Diagnosis of Neuropathic Pain (DN4) score of 2. The mean Quick-Disabilities of the Arm, Shoulder and Hand (DASH) score after treatment was 31.8 of 100. The mean ASES score was 56.2. Only 1 patient agreed to rehabilitation in a specialized center and underwent follow-up electroneuromyography. Signs of rhomboid muscle denervation were no longer present and distal motor latencies had become normal. In all cadaver dissections, the DSN originated from the C5 nerve root and did not pass through the middle scalene muscle. We identified a site of dynamic compression of the DSN by the upper part of the medial border of the scapula when the arm was raised.

DISCUSSION

DSN compression is conventionally attributed to the middle scalene muscle, but it is noteworthy that our study reveals the possibility of dynamic compression of the nerve by the proximal part of the medial border of the scapula, which occurs when the arm elevation is above 90°.

CONCLUSION

Our study reveals the possibility of dynamic compression of the DSN by the proximal part of the medial border of the scapula, which occurs when the arm is raised above 90°. In the absence of a surgical solution, conservative treatment is fundamental and requires management in a rehabilitation center with intervention by a multidisciplinary team.

Neurolysis of the distal segment of the long thoracic nerve for the treatment of scapular winging due to serratus anterior palsy: a continuous series of 73 cases

BACKGROUND

Serratus anterior (SA) palsy following mechanical injury to the long thoracic nerve (LTN) is the most common cause of scapular winging. This study aimed to identify the factors influencing the outcome of neurolysis of the distal segment of the LTN. We hypothesized that poor results are due to duration before surgery and to persistent scapulothoracic dysfunction.

METHODS

A retrospective study was conducted. The inclusion criteria were partial or complete isolated noniatrogenic SA paralysis of at least 4-month duration with preoperative electrophysiologic assessment confirming the neurogenic origin without signs of reinnervation.

RESULTS

Seventy-three patients were assessed at 45 days, 6 months, and 24 months after neurolysis of the distal segment of the LTN. At the last follow-up, improvement was excellent in 38 (52%), good in 22 cases (30%), moderate in 6 (8%), and poor in 7 (10%). No patient showed deterioration in outcomes since the beginning of follow-up. Scapular winging was no longer present in 46 cases (63%), while it was minimal in 23 (31.5%). In 4 cases (5.5%), winging was similar to the preoperative condition.

DISCUSSION

The best outcomes occurred in patients who presented without compensatory muscle pain and who were treated within 12 months of paralysis. Beyond this time frame, neurolysis can still provide useful functional improvement and avoid palliative surgery.

CONCLUSION

Neurolysis of the distal segment of the LTN is a safe and reliable procedure. This technique allows treatment of SA muscle palsy and corrects scapular winging with excellent or good outcomes in 82% of cases.

Scapular Winging following Sports-Related Injury in a Rugby Player

The most common cause of medial scapular winging is long thoracic nerve palsy (LTN) and subsequent serratus anterior muscle dysfunction. A 16-year-old right-handed male high-school rugby player developed severe right-sided neck and shoulder pain after tackling an opponent while playing rugby. Six weeks after initial injury, the patient observed shoulder muscle weakness when performing his daily activities. On physical examination, limited active elevation of the right shoulder in the scapular plane and scapular winging was observed. Magnetic resonance imaging revealed atrophy of both the SA and subclavius muscles on the right side, and we initially suspected an LTN injury sustained. However, while detailing his history, the patient explained that he also had noted difficulty sucking high viscosity drinks such as shakes and smoothies since childhood. In addition, physical examination showed weakness of the orbicularis oculi muscle. Considering the facial muscle weakness, facioscapulohumeral dystrophy (FSHD) was also suspected, and genetic testing showed chromosome 4q35 deletion with restriction fragments 17 kb and 3 tandem repeated DNA confirming the diagnosis of FSHD. Clinicians should be aware that FSHD could be one of the differential diagnoses of scapular winging after sports injury, and surgeons should rule out the diagnosis of FSHD before performing any surgical treatment for SA palsy.

Scapular winging secondary to serratus anterior dysfunction: analysis of clinical presentations and etiology in a consecutive series of 96 patients

BACKGROUND

This study aimed to establish the relative incidence of etiologies causing serratus anterior (SA) dysfunction in patients with proven abnormality on needle electromyography.

METHODS

This was a retrospective review of patients with scapular winging secondary to SA dysfunction. Each patient underwent a detailed clinical, radiological, and neurophysiological assessment to arrive at the precise etiological diagnosis. Patients with atypical clinical features were referred for a neurologist's assessment. Hematological and genetic testing were requested at the discretion of the neurologist. A scapular winging severity score based on clinical signs was devised to aid clinical grading.

RESULTS

Between 2014 and 2020, a consecutive series of 108 patients with suspected SA dysfunction were assessed, of whom 96 met the inclusion criteria. There were 34 females and 62 males, with a mean age of 38 years (range, 15-77 years). Winging affected the right scapulae in 69 patients, the left scapulae in 17 patients, and was bilateral in 10 patients. This was caused by a myopathic disorder in 12 (12%) patients. Eighty-four (88%) patients had a long thoracic nerve lesion, caused by cervical pathology (2), iatrogenic injury (2), trauma (33), and neuralgic amyotrophy (NA) (47). Among those with NA, winging resolved spontaneously within 3 years of onset in 22 patients (mean duration, 16 months; range, 3-36 months). No patients recovered fully if their duration of winging lasted longer than 3 years. Patients with palsy secondary to NA tended to have a worse severity of winging than those due to a traumatic cause (P = .04).

CONCLUSION

NA accounted for approximately half of the patients with SA dysfunction; therefore, it is essential to also consider the differentials of myopathy, trauma, iatrogenic injury, and spinal pathology. We recommend the judicious employment of ancillary tests and a low threshold of referral to a neurologist, in order to arrive at the exact diagnosis to accurately guide patient treatment.

Variation of surgical anatomy of the thoracic portion of the long thoracic nerve

Decompression of the long thoracic nerve (LTN) is a potentially beneficial procedure for selected patients with LTN palsy. The aim of this work is to describe the surgical anatomy of the thoracic part of the LTN and highlight its variations. A retrospective review of patients undergoing exploration of the LTN was performed. Preoperatively, all patients had serratus anterior dysfunction and underwent electromyographic (EMG) assessment. All patients had an initial trial of nonoperative management. The surgical procedures were undertaken by the senior author. The anatomy of the LTN and the associated vasculature was recorded in patient records, and with digital photography. Forty-five patients underwent LTN exploration. Two patients with iatrogenic injury were excluded, leaving 43 patients for analysis. Mean age was 36 years. Sixty-seven percent of cases involved the dominant side. Trauma was the commonest cause, followed by neuralgic amyotrophy. Four patients had typical features of serratus anterior dysfunction but with normal EMG studies. Two distinct patterns of LTN anatomy were noted. In 79% of cases, a single major nerve trunk coursing along serratus anterior was observed and classified as a type I LTN. In 21% of cases, two equal major branches of the nerve were identified, which was classified as a type II LTN. Approximately one in five patients may have two major branches of the LTN. This is of clinical relevance to those who undertake any thoracic procedures, as well as those who are considering exploration of the LTN.

Scapula alata: diagnosis and treatment by nerve surgery and tendon transfers

Scapula alata, also known as winged scapula, can lead to severe upper limb impairment. The shoulders' function is altered because the scapula, which supports the upper limb, is no longer stable. Typical scapula alata is described for serratus anterior palsy; however, any scapulothoracic muscle impairment may lead to scapular winging, particularly trapezius palsy, which is easy to miss, thus needed to be considered as a differential diagnosis. The diagnosis is difficult and based on various clinical tests and a thorough examination as well as electroneuromyography and MRI. The treatment ranges from conservative treatments for spontaneous recovery, nerve surgery including neurolysis, nerve transfers and nerve grafts for acute cases, to tendon transfers for more chronic cases and when nerve procedures are no longer feasible. Tendon transfers in serratus anterior palsy produce excellent results with a high rate of patient satisfaction and are described with the sternal or clavicular head of the pectoralis major; we describe our preferred technique in this article. Tendon transfers in trapezius palsy are performed with the levator scapulae, rhomboid minor and major muscles. Our preferred method is the Elhassan triple transfer. Scapula alata is a frequent and often misdiagnosed condition. Appropriate management can yield excellent results. Patients should be referred right away to specialized centers for surgery if recovery is not spontaneous.

Ultrasonographic anatomy of the long thoracic nerve: A reappraisal using high frequency (24-MHz) probe

PURPOSE

The purpose of this study was to analyze the potential of ultrasound with a high frequency probe (24-MHz) in the assessment of the long thoracic nerve (LTN) and describe ultrasonographic landmarks that can be used for standardization.

MATERIAL AND METHODS

Ultrasonography analysis of the LTN was done on 2 LTNs in a cadaver specimen and then on 30 LTNs in 15 healthy volunteers (12 men, 3 women; mean age, 28.8±3.8 [SD] years; age range: 24-39 years) by two independent radiologists (R1 and R2) using a 24-MHz probe. Interrater agreement was assessed using Kappa test (K) and intraclass correlation coefficient (ICC).

RESULTS

In the cadaver, dissection confirmed that the India ink was injected near the LTN in the middle scalene muscle. In volunteers, visibility of the LTN above the clavicle was highly reproducible for the branches arising from C5 (R1: 87% [26/30]; R2: 90% [27/30]; K=0.83) and from C6 (R1: 100% [30/30]; R2: 97% [29/30]; K=0.94). Where the nerve emerged from the middle scalene muscle, the mean diameter was 0.85±0.24 (SD) mm (range: 0.4-1.6mm) for R1 and 0.9±0.23 (SD) mm (range: 0.4-1.7mm) for R2 (ICC: 0.96; 95% CI: 0.92-0.98%). Along the thoracic wall, where LTN run along the lateral thoracic artery, the mean diameter was 0.83±0.19 (SD) mm (range: 0.5-1.27mm) for R1 and 0.89±0.21 (SD) mm (range: 0.6-1.2mm) for R2 (ICC: 0.86; 95% CI: 0.72-0.93%).

CONCLUSION

The LTN can be analyzed with ultrasound using high-frequency probe by using the C5 and C6 roots, the middle scalene muscle above the clavicle and the lateral thoracic artery on the chest wall as landmarks.

Analysis of the positional relationship of the long thoracic nerve considering clinical treatment

INTRODUCTION

The long thoracic nerve (LTN) has a risk of being damaged during chest surgery and should be considered when performing anesthesia such as a serratus anterior plane block (SAPB). We analyzed the relationship between landmarks-the fourth to ninth intercostal space (ICS) at the midaxillary line (MAL), through which the distal part of the LTN passes-and the LTN.

MATERIALS AND METHODS

We used 25 specimens from 17 embalmed Korean cadavers. The MAL, level of rib and ICS, and regions 5 cm anteroposterior to the MAL (aMAL/pMAL) were established to measure the position of the LTN crossing the MAL, pathway of the LTN, and entering points of the LTN to the SA.

RESULTS

The LTN crossed the MAL in 76% of the specimens. The LTN crossed the MAL within the fifth to sixth rib level in 70.8%. Seventy-six percent of the branches entered the SA within the fourth to sixth ICS. The fifth rib and ICS were the most frequent regions aMAL; however, several branches were found pMAL. The LTN entered the SA in 92.6% of the specimens within 3 cm anterior and 1 cm posterior to the MAL.

CONCLUSIONS

We set the danger zone as 4 cm near the MAL at the fourth to sixth ICS for thoracotomy. In addition, we proposed the fifth ICS in aMAL at the superficial plane as the alternative injection point for SAPB when blocking the LTN, and the fifth ICS in pMAL at the deep plane to prevent blocking the LTN.

Surgical and Clinical Decision Making in Isolated Long Thoracic Nerve Palsy

BACKGROUND

Isolated long thoracic nerve palsy results in scapular winging and destabilization. In this study, we review the surgical management of isolated long thoracic nerve palsy and suggest a surgical technique and treatment algorithm to simplify management.

METHODS

In total, 19 patients who required surgery for an isolated long thoracic nerve palsy were reviewed retrospectively. Preoperative demographics, electromyography (EMG), and physical examinations were reviewed. Intraoperative nerve stimulation, surgical decision making, and postoperative outcomes were reviewed.

RESULTS

In total, 19 patients with an average age of 32 were included in the study. All patients had an isolated long thoracic nerve palsy caused by either an injury (58%), Parsonage-Turner syndrome (32%), or shoulder surgery (10%); 18 patients (95%) underwent preoperative EMG; 10 with evidence of denervation (56%); and 13 patients had motor unit potentials in the serratus anterior (72%). The preoperative EMG did not correlate with intraoperative nerve stimulation in 13 patients (72%) and did correlate in 5 patients (28%); 3 patients had a nerve transfer (3 thoracodorsal to long thoracic at lateral chest, 1 pec to long thoracic at supraclavicular incision). In the 3 patients who had a nerve transfer, there was return of full forward flexion of the shoulder at an average of 2.5 months.

CONCLUSIONS

A treatment algorithm based on intraoperative nerve stimulation will help guide surgeons in their clinical decision making in patients with isolated long thoracic nerve palsy. Intraoperative nerve stimulation is the gold standard in the management of isolated long thoracic nerve palsy.

Meta-Analysis of Long Thoracic Nerve Decompression and Neurolysis Versus Muscle and Tendon Transfer Operative Treatments of Winging Scapula

Background:

Injury to long thoracic and the spinal accessory nerves can cause winging scapula as a result of weakness and paralysis of the trapezius and serratus anterior muscles. Although these nerve and muscle operations have been reported to correct winging scapula due to various causes, there is no report on comparing the outcomes of these procedures in peer-reviewed Pubmed-indexed literature. In this article, we compared the improvements in the restoration of shoulder functions in winging scapula patients after long thoracic nerve decompression (LTND) in our present study with outcomes of muscle and tendon transfer operations published in the literature (Aetna cited articles).

Methods:

Twenty-five winging scapula patients met the inclusion criteria, who had LTND and neurolysis at our clinic since 2008. Electromyographic evaluation of the brachial plexus and long thoracic nerve distribution was performed preoperatively for all our patients in this study. Operating surgeon (R.K.N.) examined all patients and measured pre- and postoperative range of motion of the affected shoulder. The mean follow-up was 23 months (range, 13–46 months). Age of our patients in this study at the time of surgery was between 13 and 63 years. These patients had winging scapula between 5 days (tennis injury) and several years before surgery and some were unknown.

Results:

Shoulder flexion and abduction improved to an average of 163˚ (P < 0.000006) and 157˚ (P < 0.0000005) from 104˚ and 97˚ at least 1-year post-LTND in 25 winging scapula patients in our present study. This is statistically significant in comparison to the reported improvements resulting from muscle and tendon transfer procedures in the Pubmed-indexed (Aetna cited) literature.

Conclusion:

This meta-analysis suggests that nerve surgeries such as LTND and neurolysis are effective techniques in correcting winging scapula in comparison with muscle transfer operations.

Reproducibility of isometric shoulder protraction and retraction strength measurements in normal subjects and individuals with winged scapula

BACKGROUND

The strength of the shoulder protractors and retractors may be compromised in individuals with winged scapula (IwWS). However, no standard approach to measuring the strength of these muscles has been described. The aim of this study was to study the intra-rater and inter-rater reproducibility of a fixed-base isometric dynamometer and to describe cutoff scores for clinically meaningful change for protraction and retraction isometric strength.

METHOD

Twice during a week, 20 normal subjects and 20 IwWS were tested by 2 independent raters.

RESULTS

IwWS were significantly weaker (P < .001) than control subjects in their protraction and retraction isometric strength. Excellent intra-rater and inter-rater correlations were obtained in most combinations, leading to low cutoff scores for meaningful change expressed in terms of the smallest real difference.

CONCLUSION

When it is properly used, the technique described in this paper is recommended as an effective clinical tool for the quantitative assessment of protraction and retraction isometric strength, both for status determination and for monitoring of change in IwWS during and after rehabilitation.

Scratch Collapse Test Is a Useful Clinical Sign in Assessing Long Thoracic Nerve Entrapment

The scratch collapse test (SCT) is a relatively new clinical test in which a positive result implies entrapment neuropathy of the nerve tested. Initially described for carpal and cubital tunnel syndromes, subsequent authors have found it useful for the assessment of median, ulna, radial, axillary, and common peroneal nerves. We report a case illustrating the value of the SCT in the clinical assessment of thoracic nerve entrapment.