Anatomy and clinical application of suprascapular nerve to accessory nerve transfer

BACKGROUND Loss of motor function in the trapezius muscle is one complication of radical neck dissection after cutting the accessory nerve(AN) during surgery.Nerve repair is an effective method to restore trapezius muscle function,and includes neurolysis,direct suture,and nerve grafting.The suprascapular nerve(SCN) and AN are next to each other in position.The function of the AN and SCN in shoulder elevation and abduction movement is synergistic.SCN might be considered by surgeons for AN reanimation.AIM To obtain anatomical and clinical data for partial suprascapular nerve-to-AN transfer.METHODS Ten sides of cadavers perfused with formalin were obtained from the Department of Human Anatomy,Histology and Embryology,Peking University Health Science Center.The SCN(n = 10) and AN(n = 10) were carefully dissected in the posterior triangle of the neck,and the trapezius muscle was dissected to fully display the accessory nerve.The length of the SCN from the origin of the brachial plexus(a point) to the scapular notch(b point) and the distance of the SCN from the origin point(a point) to the point(c point) where the AN entered the border of the trapezius muscle were measured.The length and branches of the AN in the trapezius muscle were measured.A female patient aged 55 years underwent surgery for partial SCN to AN transfer at Department of Oral and Maxillofacial Surgery,Peking University School and Hospital of Stomatology.The patient suffered from recurrent upper gingival cancer.Radical neck dissection was performed on the right side,and the right AN was removed at the intersection between the nerve and the posterior border of the SCM muscle.One-third of the diameter of the SCN was cut off,and combined epineurial and perineurial sutures were applied between the distal end of the cut-off fascicles of the SCN and the proximal end of the AN without tension.Both subjective and objective evaluations were performed before,three months after,and nine months after surgery.For the subjective evaluation,the questionnaire included the Neck Dissection Impairment Index(NDII) and the Constant Shoulder Scale.Electromyography was used for the objective examination.Data were analyzed using t tests with SPSS 19.0 software to determine the relationship between the length of the SCN and the linear distance.A P value of < 0.05 was considered as statistically significant.RESULTS The whole length of the AN in the trapezius muscle was 16.89 cm.The average numbers of branches distributed in the descending,horizontal and ascending portions were 3.8,2.6 and 2.2,respectively.The diameter of the AN was 1.94 mm at the anterior border of the trapezius.The length of the suprascapular nerve from the origin of the brachial plexus to the scapular notch was longer than the distance of the suprascapular nerve from the origin point to the point where the accessory nerve entered the upper edge of the trapezius muscle.The amplitude of trapezius muscle electromyography indicated that both the horizontal and ascending portions of the trapezius muscle on the right side had better function than the left side nine months after surgery.The results showed that the right-sided supraspinatus and infraspinatus muscles did not lose more function than the left side.CONCLUSION Based on anatomical data and clinical application,partial suprascapular nerve-to-AN transfer could be achieved and may improve innervation of the affected trapezius muscle after radical neck dissection.

Restoration of shoulder abduction by transfer of the spinal accessory nerve to suprascapular nerve through dorsal approach: a clinical study

Background In recent years, transfer of the spinal accessory nerve to suprascapular nerve has become a routine procedure for restoration of shoulder abduction. However, the operation via the traditional supraclavicular anterior approach often leads to partial denervation of the trapezius muscle. The purpose of the study was to introduce transfer of the spinal accessory nerve through dorsal approach, using distal branch of the spinal accessory nerve, to repair the suprascapular nerve for restoration of shoulder abduction, and to observe its therapeutic effect. Methods From January to October 2003, a total of 11 patients with a brachial plexus injury and an intact or nearly intact spinal accessory nerve were treated by .transferring the spinal accessory nerve to the suprascapular nerve through dorsal approach. The patients were followed up for 18 to 26 months [mean （23.5 ±5.2） months] to evaluate their shoulder abduction and function of the trapezius muscle. The outcomes were compared with those of 26 patients treated with traditional anterior approach. And the data were analyzed by Student＇s t test using SPSS 10.5.Results In the 11 patients, the spinal accessory nerves were transferred to the suprascapular nerve through the dorsal approach successfully. Intact function of the upper trapezius was achieved in all of them. In the patients, the location of the two nerves was relatively stable at the level of superior margin of the scapula, the mean distance between them was （4.2± 1.4） cm, both the nerves could be easily dissected and end-to-end anastomosed without any tension. During the follow-up, the first electrophysiological sign of recovery of the infraspinatus appeared at （6.8±2.7） months and the first sign of restoration of the shoulder abduction at （7.6±2.9） months after the operation, which were earlier than that after the traditional operation [（8.7±2.4） months and （9.9±2.8） months, respectively; P〈0.05]. The postoperative shoulder abduction was 62.8°±12.6° after transfer of the spinal accessory nerve, better than that after the traditional （51.6°15.7°）. All the 11 patients could extend and externally rotate the shoulder almost normally. Condusions The accessory nerve transfer through dorsal approach is a safe and reliable procedure for the treatment of brachial plexus injury. Its postoperative effect is confirmed, which is better than that of the traditional operation.