Long Thoracic Nerve Palsy: When Is Decompression Indicated

Abstract

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 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. Normal scapular function is essential for optimal shoulder function. Precise scapular control allows the optimal positioning of the humerus in relation to the glenoid, thus transferring power from the core to the upper extremity. Disturbance of this function may manifest as scapular winging. It only refers to the abnormal prominence of the scapula and does not imply an etiological basis. The abnormality can be static—where the resting position is protracted compared with the contralateral side—or dynamic–where the normal smooth scapulothoracic motion is disrupted, which is known as scapular dyskinesis, scapula dysrhythmia, or scapulothoracic abnormal motion.1Kibler W.B. Ludewig P.M. McClure P.W. Michener L.A. Bak K. Sciascia A.D. Clinical implications of scapular dyskinesis in shoulder injury: the 2013 consensus statement from the “Scapular Summit.”.Br J Sports Med. 2013; 47: 877-885Crossref PubMed Scopus (368) Google Scholar, 2Roche S.J. Funk L. Sciascia A. Kibler W.B. Scapular dyskinesis: the surgeon’s perspective.Shoulder Elbow. 2015; 7: 289-297Crossref PubMed Scopus (28) Google Scholar, 3Elhassan B.T. Dang K.H. Huynh T.M. Harstad C. Best M.J. Outcome of arthroscopic pectoralis minor release and scapulopexy for the management of scapulothoracic abnormal motion.J Shoulder Elbow Surg. 2022; 31: 1208-1214Abstract Full Text Full Text PDF PubMed Scopus (2) Google Scholar Scapular winging can be painful, functionally limiting, and cosmetically unsightly, which frequently requires consideration for treatment. Scapular motion is controlled by the coordinated action of up to 17 periscapular muscles. Of these, the serratus anterior (SA) is the most commonly implicated muscle in scapular dyskinesis.4Gooding B.W.T. Geoghegan J.M. Wallace W.A. Manning P.A. Scapular winging.Shoulder Elbow. 2014; 6: 4-11Crossref PubMed Scopus (17) Google Scholar It is a large flat muscle, originating from the upper eighth to ninth ribs to insert on the costal surface of the medial border of the scapula. It is innervated by the long thoracic nerve (LTN). The SA works as a force couple in conjunction with the trapezius and rhomboid muscles to anchor the scapula to the chest wall stably.2Roche S.J. Funk L. Sciascia A. Kibler W.B. Scapular dyskinesis: the surgeon’s perspective.Shoulder Elbow. 2015; 7: 289-297Crossref PubMed Scopus (28) Google Scholar Dysfunction of the SA causes failure of this force couple, resulting in medial winging. The dysfunction may be due to a myopathic or neurogenic process, with the latter accounting for the majority of cases.5Ng C.Y. Wu F. Scapular winging secondary to serratus anterior dysfunction: analysis of clinical presentations and etiology in a consecutive series of 96 patients.J Shoulder Elbow Surg. 2021; 30: 2336-2343Abstract Full Text Full Text PDF Scopus (2) Google Scholar Conversely, when there is a dysfunction of the trapezius or rhomboid muscles, the aberrant forces directed at the scapula are reversed, resulting in lateral winging. Long thoracic nerve palsy may arise from direct injury to the nerve (such as thoracic trauma or surgery), traction injury, or neuralgic amyotrophy (NA). Historically, the expectation of LTN palsy as a result of closed trauma or neuritis has been of spontaneous resolution, with its natural history suggesting that symptoms do not last beyond 2 years.6Gregg J.R. Labosky D. Harty M. et al.Serratus anterior paralysis in the young athlete.J Bone Joint Surg Am. 1979; 61: 825-832Crossref PubMed Scopus (158) Google Scholar However, more recent studies suggest that a significant proportion of patients may continue to suffer from pain and restriction beyond the expected time of recovery.7Pikkarainen V. Kettunen J. Vastamäki M. The natural course of serratus palsy at 2 to 31 years.Clin Orthop Relat Res. 2013; 471: 1555-1563Crossref PubMed Scopus (14) Google Scholar This group of patients may benefit from surgical treatment targeted at the LTN. Nonetheless, there is no consensus on the optimal strategy. This review examines our current understanding of LTN palsy and explores the varying treatment strategies with their reported outcomes. The authors also propose a treatment algorithm based on the literature and their clinical experience. The anatomy of the LTN is variable. It is a motor nerve that originates from the ventral rami of the fifth, sixth, and seventh cervical roots in the majority, but can have contributions from C4 or C8.8Wang J.F. Dang R.S. Wang D. et al.Observation and measurements of long thoracic nerve: a cadaver study and clinical consideration.Surg Radiol Anat. 2008; 30: 569-573Crossref PubMed Scopus (18) Google Scholar Branches can also be absent from C5 or C7 in up to 15% and 3% of cases, respectively. It averages 27 cm in length and remains superficial for most of its course.9Tubbs R.S. Salter E.G. Custis J.W. Wellons III, J.C. Blount J.P. Oakes W.J. Surgical anatomy of the cervical and infraclavicular parts of the long thoracic nerve.J Neurosurg. 2006; 104: 792-795Crossref PubMed Scopus (28) Google Scholar In 50% of patients, the fifth and sixth roots tend to pass between the middle and posterior scalene muscles, with the remainder traveling either through the middle scalene or anterior to this muscle.9Tubbs R.S. Salter E.G. Custis J.W. Wellons III, J.C. Blount J.P. Oakes W.J. Surgical anatomy of the cervical and infraclavicular parts of the long thoracic nerve.J Neurosurg. 2006; 104: 792-795Crossref PubMed Scopus (28) Google Scholar The seventh root always passes anterior to the middle scalene muscle and joins the C5 and C6 contributions at the level of the second rib. All contributions travel deep to the brachial plexus before passing over the first rib and descending along the lateral aspect of the chest wall as inferiorly as the ninth rib, superficial to the SA. Its sole innervation is into the SA. Its small diameter, superficial location, and lengthy course make it vulnerable to injury. Although a few potential compression sites exist, the exact location of where the nerve is constricted, and thus, the location of surgical decompression, remains controversial. It is thought to be prone to compression as it pierces through the scalenus medius and crosses the second rib. It may also be compressed extrinsically by the complex arrangement of traversing branches of the thoracodorsal artery, known as the “crow’s foot” (Fig. 1).10Ormsby N.M. Hawkes D.H. Ng C.Y. Variation of surgical anatomy of the thoracic portion of the long thoracic nerve.Clin Anat. 2022; 35: 442-446Crossref Scopus (0) Google Scholar A recent clinical study has shown that 2 variations exist in the anatomy of the thoracic part of the LTN.10Ormsby N.M. Hawkes D.H. Ng C.Y. Variation of surgical anatomy of the thoracic portion of the long thoracic nerve.Clin Anat. 2022; 35: 442-446Crossref Scopus (0) Google Scholar A type I LTN is more common and its distribution is classically described in the literature as a nerve that be superficial to the SA minor branches along its A type LTN in of patients with LTN where the nerve into 2 at or to the with minor The authors that patients with LTN palsy be more to have in their anatomy The most common of scapular winging reported in the literature is medial winging due to SA dysfunction LTN and management of scapular Surg Am. Full Text Full Text PDF PubMed Scopus Google Scholar the LTN is the classically described clinical is a scapula that a position of medial and of the and management of scapular Surg Am. Full Text Full Text PDF PubMed Scopus Google Scholar The medial border of the scapula more as the SA is no to the scapula the thoracic and the of more as the muscle more winging of the scapula is less common and to trapezius due to nerve palsy or rhomboid muscle paralysis due to injury of the scapular In lateral winging, the shoulder with an of the and the This can be a and the can the lateral and management of scapular Surg Am. Full Text Full Text PDF PubMed Scopus Google Scholar In our scapular winging a of at the of the may only with a scapular on shoulder In at the can winging at there being a of scapular winging, there is no clinical to its S.J. Funk L. Sciascia A. Kibler W.B. 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Clinical implications of scapular dyskinesis in shoulder injury: the 2013 consensus statement from the “Scapular Summit.”.Br J Sports Med. 2013; 47: 877-885Crossref PubMed Scopus (368) Google Scholar of SA dysfunction the scapular scapular and the shoulder In the scapular the and on the border of the the serratus anterior W.B. Ludewig P.M. McClure P.W. Michener L.A. Bak K. Sciascia A.D. Clinical implications of scapular dyskinesis in shoulder injury: the 2013 consensus statement from the “Scapular Summit.”.Br J Sports Med. 2013; 47: 877-885Crossref PubMed Scopus (368) Google Scholar of pain through the of shoulder motion of motion is a result muscle The scapular is by the scapula in a position on the F. J. 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Scapular winging secondary to serratus anterior dysfunction: analysis of clinical presentations and etiology in a consecutive series of 96 patients.J Shoulder Elbow Surg. 2021; 30: 2336-2343Abstract Full Text Full Text PDF Scopus (2) Google Scholar trauma is due to as first rib and which for to of in the C.Y. Wu F. Scapular winging secondary to serratus anterior dysfunction: analysis of clinical presentations and etiology in a consecutive series of 96 patients.J Shoulder Elbow Surg. 2021; 30: 2336-2343Abstract Full Text Full Text PDF Scopus (2) Google M. in paralysis of the serratus anterior a of Shoulder Elbow Surg. Full Text PDF PubMed Scopus Google Scholar LTN palsy is to also known as and brachial It is a clinical by of pain by in the upper and in neuralgic Full Text Full Text PDF PubMed Scopus Google Scholar It is by an but may occur It has also been with and A is through an C.Y. Wu F. 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