Transient long thoracic nerve injury during posterior spinal fusion for adolescent idiopathic scoliosis: A report of two cases

We present the transient long thoracic nerve (LTN) injury during instrumented posterior spinal arthrodesis for idiopathic scoliosis. The suspected mechanism of injury, postoperative course and final outcome is discussed. The LTN is susceptible to injury due to its long and relatively superficial course across the thoracic wall through direct trauma or tension. Radical mastectomies with resection of axillary lymph nodes, first rib resection to treat thoracic outlet syndrome and cardiac surgery can be complicated with LTN injury. LTN injury producing scapular winging has not been reported in association with spinal deformity surgery. We reviewed the medical notes and spinal radiographs of two adolescent patients with idiopathic scoliosis who underwent posterior spinal arthrodesis and developed LTN neuropraxia. Scoliosis surgery was uneventful and intraoperative spinal cord monitoring was stable throughout the procedure. Postoperative neurological examination was otherwise normal, but both patients developed winging of the scapula at 4 and 6 days after spinal arthrodesis, which did not affect shoulder function. Both patients made a good recovery and the scapular winging resolved spontaneously 8 and 11 months following surgery with no residual morbidity. We believe that this LTN was due to positioning of our patients with their head flexed, tilted and rotated toward the contralateral side while the arm was abducted and extended. The use of heavy retractors may have also applied compression or tension to the nerve in one of our patients contributing to the development of neuropraxia. This is an important consideration during spinal deformity surgery to prevent potentially permanent injury to the nerve, which can produce severe shoulder dysfunction and persistent pain.