Surgical Restoration of Shoulder Function in 270 Patients With Scapulothoracic Abnormal Motion (STAM, Type 3) due to Serratus Anterior Palsy

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

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

Dorsal scapular nerve injury: a complication of ultrasound-guided interscalene block

Winged scapula is a rare condition caused by injuries to the long thoracic nerve (LTN) and accessory nerves. A 69-year-old man underwent surgery for right lung cancer. Video-assisted thoracic surgery...

The long thoracic nerve (LTN) innervates the serratus anterior muscle (SA) which plays an important role in shoulder function. Evaluation of the LTN has so far been restricted to clinical assessment and partly electromyography and neurography. Progress of high-resolution ultrasound (HRUS) increasingly enables visualization of small peripheral nerves and their pathologies. We therefore aimed at (a) clarifying the possibility of visualization of the LTN from its origin to the most distal point in the supraclavicular region visible and (b) developing an ultrasound protocol for routine use. We further present two cases of patients with LTN pathology. The study consisted of two parts: Part 1 included 4 non-enbalmed human bodies in whom the LTN (n = 8) was located and then marked by ink injection. Correct identification was confirmed by anatomical dissection. Part 2 included 20 healthy volunteers whose LTN (n = 40) was assessed independently by two radiologists. Identification of the LTN was defined as consensus in recorded images. LTN was clearly visible in all anatomical specimens and volunteers using HRUS and could be followed until the second slip of the serratus anterior muscle from the supraclavicular region. In anatomical specimens, dissection confirmed HRUS findings. For all volunteers, consensus was obtained. The mean nerve diameter was 1.6 mm ± 0.3 (range 1.1 - 2.1 mm) after the formation of the main trunk. We hereby confirm a reliable possibility of visualization of the LTN in anatomical specimens as well as in volunteers. We encourage HRUS of the LTN to be part of the diagnostic work-up in patients presenting with scapular winging, shoulder weakness or pain of unknown origin.

Parsonage-Turner syndrome (PTS) is characterized by severe, acute upper extremity pain and subsequent paresis and most commonly involves the long thoracic nerve (LTN). While MR neurography (MRN) can detect LTN hourglass-like constrictions (HGCs), quantitative muscle MRI (qMRI) can quantify serratus anterior muscle (SAM) neurogenic changes. 1) To characterize qMRI findings in LTN-involved PTS. 2) To investigate associations between qMRI and clinical assessments of HGCs/electromyography (EMG). Prospective. 30 PTS subjects (25 M/5 F, mean/range age = 39/15-67 years) with LTN involvement who underwent bilateral chest wall qMRI and unilateral brachial plexus MRN. 3.0 Tesla/multiecho spin-echo T2-mapping, diffusion-weighted echo-planar-imaging, multiecho gradient echo. qMRI was performed to obtain T2, muscle diameter fat fraction (FF), and cross-sectional area of the SAM. Clinical reports of MRN and EMG were obtained; from MRN, the number of HGCs; from EMG, SAM measurements of motor unit recruitment levels, fibrillations, and positive sharp waves. qMRI/MRN were performed within 90 days of EMG. EMG was performed on average 185 days from symptom onset (all ≥2 weeks from symptom onset) and 5 days preceding MRI. Paired t-tests were used to compare qMRI measures in the affected SAM versus the contralateral, unaffected side (P < 0.05 deemed statistically significant). Kendall's tau was used to determine associations between qMRI against HGCs and EMG. Relative to the unaffected SAM, the affected SAM had increased T2 (50.42 ± 6.62 vs. 39.09 ± 4.23 msec) and FF (8.45 ± 9.69 vs. 4.03% ± 1.97%), and decreased muscle diameter (74.26 ± 21.54 vs. 88.73 ± 17.61 μm) and cross-sectional area (9.21 ± 3.75 vs. 16.77 ± 6.40 mm2). There were weak to negligible associations (tau = -0.229 to <0.001, P = 0.054-1.00) between individual qMRI biomarkers and clinical assessments of HGCs and EMG. qMRI changes in the SAM were observed in subjects with PTS involving the LTN. 2 TECHNICAL EFFICACY: Stage 1.

The purpose of this dissection study was to explore the anatomy of the long thoracic nerve (LTN) and its origin, configuration, branching pattern and relation with scalenus muscles. Fifteen embalmed cadavers (30 sides) were used. Bilateral neck, brachial plexus and chest wall were dissected. The LTN origin trajectory, branches and relation with middle scalenus muscle were explored. The serratus anterior muscle was dissected, the portions were separated, and their LTN branches were investigated. Most common form of the long thoracic nerve is formed by an upper portion origin from the C5 and C6 nerve roots and a lower portion origin from the C7 nerve root. In one case, the LTN was forming C6, C7 and C8, in which C6 nerve root forms upper portion and C7, C8 nerves root form lower portion. In some cases, the long thoracic nerve was formed only by C5 and C6 or C6 and C7 nerve roots. We defined four different types for these LTN configurations. When we look relationship between the roots of the nerve and scalenus muscle; nerve roots mostly (C5 and C6 components or upper portion of the LTN) lay between the middle and posterior scalene muscles, sometimes traveled through the middle scalene muscle, less frequently course over the middle scalenus muscle. The C7 contribution (lower portion of the LTN) to the LTN was always located anterior to the middle scalene muscle. The C8 (in one case) also was found over the middle scalenus muscle. Each of the LTN has 7–13 branches and 0–4 branches arising directly from the nerve roots or before exact nerve configuration, 5–7 branches origin from the main trunk of the nerve. We defined these branches as ribs and intercostals spaces. We hope that this study will be helpful for many neurosurgical procedures and anatomic studies.

Previous studies have reported that motoneurons from the sixth spinal nerve (C6) innervate the majority of muscle fibers in the rat serratus anterior (SA) muscle. The seventh spinal nerve (C7) innervates a limited number of SA fibers, increasing caudally. This topographic map is partially reestablished following denervation. In the present study, muscle fibers of the SA were stained with monoclonal antibodies for the muscle-specific fast myosin heavy chain (F-MHC) and slow myosin heavy chain (S-MHC) proteins. We found that the majority of fibers in the SA muscle stained for F-MHC antibody, and the percentage of muscle fibers staining for S-MHC antibody increased caudally. When newborn SA muscles were denervated and then reinnervated by the entire long thoracic (LT) nerve or only the C6 branch to the LT nerve, the reinnervated muscle had the normal proportion of muscle fibers expressing S-MHC protein. However, if the LT nerve was crushed and only C7 motoneurons allowed to reinnervate the SA muscle, a greater percentage of muscle fibers stained for S-MHC antibody than normal. We conclude that there is a correlation between muscle fiber type and innervation topography in the SA muscle of the rat.

Thoracic Nerve, Long

The most common etiologic cause of winged scapula (WS) is paralysis of the serratus anterior muscle (SAM), typically due to an injury of the long thoracic nerve (LTN), often associated with overhead activities, including heavy weightlifting. Herein, we reported a 30-year-old male patient with WS secondary to an LTN lesion caused by carrying weight under the armpit, rather than overhead, which differs from previous reports regarding the anatomical site and cause of the LTN lesion. The ultrasonographic technique used to evaluate distal lesions of the LTN was described in detail, with the SAM thickness significantly reduced and the cross-sectional area of the LTN increased on the symptomatic side. Electroneuromyography revealed an acute/subacute, mild partial axonal lesion of the LTN, with ultrasonographic evaluation pinpointing the exact anatomical location of the lesion. Ultrasonography should be the first imaging modality used to support electrophysiological studies and evaluate the affected nerves and muscles to reveal precise anatomical localization.

BackgroundSudden cardiac death is a severe health issue, responsible for many deaths annually in the United States. It occurs unexpectedly in individuals without a prior diagnosis of a life-threatening condition. Implantable cardiac defibrillators (ICDs), introduced in the 1980s, have been pivotal in improving survival rates for high-risk patients by detecting and correcting dangerous cardiac rhythms. Traditional transvenous ICD implantation, involving leads threaded through veins, carries risks such as vascular damage and infection. Nontransvenous ICD options, such as subcutaneous ICDs (S-ICDs) and extravascular ICDs, present alternative approaches that may reduce these risks. Implantation techniques for S-ICDdevices have evolved greatly over the years, with the most recently recommended approach being an intermuscular technique. However, this anatomical space has not been adequately studied.ObjectiveThe purpose of this study was to better understand the anatomical variations associated with S-ICD implantation.MethodsThis investigation involved a detailed examination of 18 cadaveric specimens (12 females and 6 males) to map the anatomical relationships between the latissimus dorsi muscle (LDM), the serratus anterior muscle, and the long thoracic nerve (LTN), which are critical for refining nontransvenous ICD implantation techniques. Measurements included the distance from the anterior border of the LDM to the back, the anterior-posterior diameter of the chest at the fifth and seventh rib levels, and the positioning of the LTN relative to the chest wall.ResultsThe analysis showed that at the fifth rib level, the average distance from the back to the LDM border was 7.5 cm, and at the seventh rib level, it was 7.6 cm. The overall average distance from the back to the LDM border across both rib levels was 7.5 cm. The LTN was positioned at an average distance of 8.5 cm from the back at the fourth rib, decreasing to 5.7 cm at the sixth rib. The LTN tended to be more anterior in males than in females, but this difference was not statistically significant.ConclusionThe findings highlight the importance of accurate anatomical knowledge for the effective placement of nontransvenous ICDs. Understanding the specific anatomical layout of the LDM, the serratus anterior muscle, and the LTN is crucial to prevent complications such as LTN injury and to improve the safety and efficacy of ICD implantation. The results advocate for personalized assessment approaches to improve procedural success and patient outcomes in nontransvenous ICD implantation.

Long thoracic nerve (LTN) injury can result in ipsilateral serratus anterior palsy and scapular winging. Traditional means of evaluating patients with suspected LTN injury include physical examination and electrodiagnostic studies. The purpose of our study is to describe high-resolution magnetic resonance (MR) findings in patients with clinical suspicion of LTN neuropathy. In this HIPAA-compliant, IRB-approved, retrospective study, two radiologists reviewed MR imaging performed for long thoracic neuropathy. Clinical presentation, electrodiagnostic studies and MR imaging of 20 subjects [mean age 37±13years; 25% (5/20) female] were reviewed. Observers reviewed MR imaging for LTN signal intensity, size, course, presence or absence of mass and secondary findings [skeletal muscle denervation (serratus anterior, trapezius, rhomboid) and scapular winging]. Descriptive statistics were reported. Clinical indications included trauma (n=5), hereditary neuropathy (n=1), pain (n=8), winged scapula (n=6), brachial plexitis (n=4) and mass (n=1). Electrodiagnostic testing (n=7) was positive for serratus anterior denervation in three subjects. Abnormal LTN signal intensity, size, course or mass was present in 0/20. Secondary findings included skeletal muscle denervation in the serratus anterior in 40% (8/20), trapezius in 20% (4/20) and rhomboid in 20% (4/20). In 5% (1/20), an osteochondroma simulated a winged scapula, and in 2/20 (10%) MR showed scapular winging. High-resolution MR imaging is limited in its ability to visualize the long thoracic nerve directly, but does reveal secondary signs that can confirm a clinical suspicion of LTN injury.

The paper presents a 33 - year - old patient who has been suffering from ankylosing spondylitis since the age of 28. Pain in his right shoulder and weakness in his right arm developed after more hours of walking with a backpack. The performed procedure diagnosed a lesion of the long thoracic nerve without of sensory damage. Peripheral nerve injuries long thoracic nerve lead to weakness of the muscles -serratus anterior muscle and result in a protrusion of the medial side of the scapula (scapula alata). It is difficult to raise the arm in the shoulder joint above the horizontal line, that is to raise the shoulder from the chest when the arm is extended and pressed against a fixed object in front of the patient. Due to its long, relatively superficial course, long thoracic nerve is susceptible to injury, either through direct trauma or stretching. The long thoracic nerve, also called Charles Bell’s external respiratory nerve, is a rare isolated nerve damage. The nerve is often injured from carrying a load on his shoulder, with supraclavicular and axillary injuries, blows in the neck area. Injury has been reported in almost all sports, usually occurring from a blow to the ribs with an outstretched arm. Long thoracic nerve can be damaged during breast cancer surgery, especially radical mastectomy that involve the removal of axillary lymph nodes. It is a common lesion in spinal surgeries. Key words: Lesion, long thoracic nerve, ankylosing spondylitis

BackgroundRecently, ultrasound has been commonly used. Ultrasound-guided interscalene brachial plexus block (IBPB) by posterior approach is more commonly used because anterior approach has been reported to have the risk of phrenic nerve injury. However, posterior approach also has the risk of causing nerve injury because there are risks of encountering dorsal scapular nerve (DSN) and long thoracic nerve (LTN). Therefore, the aim of this study was to evaluate the risk of encountering DSN and LTN during ultrasound-guided IBPB by posterior approach.MethodsA total of 70 patients who were scheduled for shoulder surgery were enrolled in this study. After deciding insertion site with ultrasound, awake ultrasound-guided IBPB with nerve stimulator by posterior approach was performed. Incidence of muscle twitches (rhomboids, levator scapulae, and serratus anterior muscles) and current intensity immediately before muscle twitches disappeared were recorded.ResultsOf the total 70 cases, DSN was encountered in 44 cases (62.8%) and LTN was encountered in 15 cases (21.4%). Both nerves were encountered in 10 cases (14.3%). Neither was encountered in 21 cases (30.4%). The average current measured immediately before the disappearance of muscle twitches was 0.44 mA and 0.50 mA at DSN and LTN, respectively.ConclusionsPhysicians should be cautious on the risk of injury related to the anatomical structures of nerves, including DSN and LTN, during ultrasound-guided IBPB by posterior approach. Nerve stimulator could be another option for a safer intervention. Moreover, if there is a motor response, it is recommended to select another way to secure better safety.

Previous studies have shown remarkable rostrocaudal selectivity by regenerating motoneurons to the rat serratus anterior (SA) muscle after freezing, crushing, or sectioning the long thoracic (LT) nerve. The LT nerve contains motoneurons from both the sixth and seventh cervical spinal nerves (C6 and C7), with C6 motoneurons as the major source of innervation throughout the muscle, and with C7 motoneurons innervating a larger percentage of muscle fibers caudally than rostrally. To determine if synaptic competition can play a role in neuromuscular topography, both the LT nerve and the branch carrying C6 (rostral) motoneurons to the LT nerve were crushed in newborn rats. This approach provides a temporal advantage to regenerating C7 (caudal) motoneurons. After an initial period during which C7 motoneurons reinnervated a larger proportion of muscle fibers than normal in all SA muscle sectors, C6 motoneurons regained their original proportion of rostral muscle fibers. Caudally, however, C7 motoneurons maintained an expanded territory. With this two-site crush method, the number of C6 motoneurons that reinnervate the SA muscle was significantly decreased from normal, whereas the number of C7 motoneurons remained the same. It is concluded that when C7 motoneurons are given a temporal advantage, synaptic specificity can be altered transiently in rostral muscle sectors and permanently in caudal sectors, and this is correlated with a disproportionate loss of C6 motoneurons. Moreover, this may be an important model for studies of synaptic competition, where terminals destined to be eliminated can be identified beforehand.