Ann Thorac Surg 2009;87:1277-1279. doi:10.1016/j.athoracsur.2008.08.050
© 2009 The Society of Thoracic Surgeons
Case Reports
Winged Scapula After Aortic Valve Replacement
Christoph Schmitz, MDa,*,
Ralf Sodian, MDa,
Thomas N. Witt, MDb,
Gerd Juchem, MDa,
Nora Lang, MDc,
Christian Bruegger, MDd,
Christian Kowalski, MDd,
Bruno Reichart, MDa
a Department of Cardiac Surgery, University of Munich, Munich, Germany
b Department of Neurosurgery, University of Munich, Munich, Germany
c Department of Pediatric Cardiology, University of Munich, Munich, Germany
d Department of Anesthesiology, University of Munich, Munich, Germany
Accepted for publication August 20, 2008.
* Address correspondence to Dr Schmitz, Department of Cardiac Surgery, University of Munich, Marchioninistr. 15, Munich, 81377, Germany (Email: christoph.schmitz{at}med.uni-muenchen.de).
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Abstract
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Iatrogenic nerve lesions affecting the long thoracic nerve are very rare after a median sternotomy. Here we report on a patient who developed clinical signs of a so-called "winged scapula" after an uneventful aortic valve replacement for infective endocarditis.
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Introduction
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Iatrogenic nerve lesions affecting the brachial plexus have been reported in up to 38% of patients after heart surgery [1]. In contrast, lesions of the long thoracic nerve are extremely rare, although the nerve is vulnerable to damage at various levels due to its long and superficial course. The long thoracic nerve is purely a motor nerve that supplies the serratus anterior muscle [2], which when paralyzed leads to the clinical symptom of the so-called "winged scapula." In this condition, the surface of the scapula moves away from the thoracic wall, the shoulder falls downward, and the arm can not be lifted higher than 90° when it is stretched sideways.
We report on the case of a 66-year-old woman with postoperative winged scapula after valve replacement for aortic valve endocarditis. Our patient weighed 65 kg and presented with acute infective endocarditis of the aortic valve. Transthoracic echocardiography revealed severe aortic insufficiency with normal left ventricular function. Angiography showed no sign of coronary artery disease.
During surgery the patient received an arterial line into the right radial artery, as well as a two-lumen catheter and a sheath into the right jugular vein. Standard aortic valve replacement was performed by a midline sternotomy. The ascending aorta and right atrial appendage were cannulated and cardiopulmonary bypass was installed. After cross clamping the aorta, a transverse incision was made, and cardioplegia was administered directly into the coronary ostia. The leaflets of the aortic valve were resected. There were no signs of annular infections. A tissue valve (Carpentier Edwards Perimount 21 mm; Edwards Lifesciences Inc, Irvine, CA) was implanted using Teflon-armed U-stitches (Ethicon Inc, Johnson & Johnson, Norderstedt, Germany). After closure of the aorta and reperfusion, cardiopulmonary bypass was stopped and all cannulae were removed. Total cardiopulmonary bypass time was 99 minutes and aortic cross-clamp time was 49 minutes. The sternum was fixed with standard sternal wires. Total operative time was 197 minutes.
The patient was weaned from the ventilator after 10 hours, was transferred to the normal ward on the second postoperative day, and to a rehabilitation unit on postoperative day 12. Her postoperative course was uneventful. During rehabilitation, the patient realized that she was not able to lift her right arm higher than 90°. The scapula moved away from the chest wall (Fig 1). Neurologic examination, including electromyography, revealed an isolated lesion of the long thoracic nerve.
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Comment
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After cardiac surgery, complications affecting the brachial plexus nerve system have been reported in up to 38 % of cases [1]. The inferior nerve roots, medial cord, and ulnar branch are most commonly involved, typically on the left side. The most important cause of damage is generally considered to be due to spreading the chest during open heart surgery. The nerve roots are anchored to their exit points from the vertebral canal and any mechanical action that stretches the nerve roots may lead to nerve injury. Nerve damage is often seen in male patients after harvesting the internal mammary artery.
Theoretically, all nerves of the brachial plexus are susceptible to iatrogenic damage. There are numerous factors under discussion in the literature (eg, the position of the patient on the operating table and the position of the superior limbs or the head and neck). Catheterization of the jugular vein can sever a nerve, most likely in one of the superior structures [3].
The long thoracic nerve is purely a motor nerve. It is formed by anterior branches of the fifth, sixth, and seventh cervical roots [4] and supplies the anterior serratus muscle. The fifth and sixth branches join beneath the scalenus medius muscle to form the upper division of the long thoracic nerve. The union of the upper division with the branch from C7 occurs caudally, in the axillary region [2]. The long and superficial course of the nerve makes it susceptible to damage at various levels. The anterior serratus muscle is a large muscle that arises from the external surface of the first eight ribs and attaches to the costal surface of the scapula. It has an important role in the abduction and elevation of the arm, and it can act as an accessory muscle in lifting the ribs during inspiration. It fixes the medial rim of the scapula to the chest wall. Paralysis of the serratus anterior muscle leads to the clinical sign of the so-called "winged scapula." In this condition, the medial surface of the scapula moves away from the thoracic wall, the shoulder falls downward, and the arm can no longer be lifted higher than 90° when it is stretched sideways. This movement of the scapula typically becomes obvious when the patient attempts to move his or her arm forward.
Besides the clinical impression, electromyography is the critical tool for diagnosing an isolated thoracic nerve lesion. Active denervation (eg, fibrillation, potentials, positive sharp waves) is solely found in the serratus anterior muscle. The electromyography of the serratus anterior muscle requires an experienced investigator. The muscle may be entered in the mid-axillary line on the level of the sixth rib. A needle electrode is inserted exactly in the muscle above the rib, which is identified by placing fingers in the fifth and sixth intercostals spaces, respectively. This maneuver prevents an unintentional penetration of the pleura leading to pneumothorax. For differential diagnosis, it is important to exclude a lesion of the accessory and dorsal scapula nerve by electromyographic examination of the trapezius and rhomboideus muscle.
Damage to the long thoracic nerve has been described after both traumatic and non-traumatic events. The reported anecdotal cases of traumatic winged scapula were usually related to traction injury of the long thoracic nerve (eg, during sports activities) [5–7]. Nontraumatic causes are viral and nonviral diseases, immunizations, vitamin deficiency diseases, metabolic disorders, and toxins [8].
Injury of the long thoracic nerve after cardiac surgery is extremely rare. In one case report the thoracic nerve was injured after port-access minimally invasive mitral valve surgery [9]. Although it is clear that lateral approaches may increase the risk of nerve injury, the reason for thoracic nerve injury is not always obvious when performing the operation through a median sternotomy. In another case report of thoracic nerve injury after median sternotomy [10] the sternum was spread extensively because both internal mammary arteries were harvested. However, in our case, the spreading of the sternum was minimal, and total operative time was normal at 197 minutes.
In our patient, almost any of the perioperative events previously described could have damaged the long thoracic nerve. Furthermore, the cause could be any maneuver carried out during the hospital stay from transporting the patient to the operating theater to transferring her from one bed to another. We were unable to find a direct explanation for the injury of this patient.
As it is difficult to identify the real reason for the damage, there is little chance to omit this rare complication in the future. The most essential lesson is to keep in mind that every action performed on an anesthetized and immobilized patient may lead to peripheral nerve damage.
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References
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- Mihm FG, Rosenthal MH. Central venous catheterizationIn: Benumof JL, editor. Clinical procedures in anesthesia and intensive care. Philadelphia: JB Lippincott; 1992. pp. 339-373.
- Gardner E, Gray DJ, O'Rahilly R. Anatomy: a regional study of human structure4th ed.. Philadelphia: WB Saunders; 1975.
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- Mah JY, Otsuka NY. Scapular winging in young athletes J Pediatr Orthop 1992;12:245-247.[Medline]
- Bunker T. Paralysis and dystrophy around the shoulderIn: Bunker T, Schranz PJ, editors. Clinical challenges in orthopedics: the shoulder. Oxford: Isis Medical Media; 1998.
- Chaney MA, Morales M, Bakhos M. Severe incisional pain and long thoracic nerve injury after port-access minimally invasive mitral valve surgery Anesth Analg 2000;91:288-290.[Abstract/Free Full Text]
- Bizzarri F, Davoli G, Bouklas D, et al. Latrogenic injury to the longthoracic nerve: an underestimated cause of morbidity after cardiac surgery Tex Heart Inst J 2001;28:315-317.[Medline]
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Abstract
Introduction
