1. The Role of Ultrasound in Surgical Decision-making for Iatrogenic Spinal Accessory Nerve Injuries A Paradigm Shift
Alper Cesmebasi, MD1,2, Jay Smith, MD3, Robert J Spinner, MD1
1 Department of Neurologic Surgery, Mayo Clinic, Rochester, MN, USA
2 Department of Anatomical Sciences, St George’s University, Grenada, West Indies
3 Department of Physical Medicine and Rehabilitation, Mayo Clinic, Rochester, MN, USA
32nd Annual Meeting of the American Association of Clinical Anatomists
10 June 2015
test

2. Background
Iatrogenic spinal accessory nerve (SAN) injury is a well-described complication with surgical procedures of the posterior cervical triangle
Most commonly associated with cervical lymph node biopsy
Affects 3-6% of all patients
Major cause for malpractice litigation
Early diagnosis and management are crucial to restore shoulder stability and function

3. Methods
Patients with suspected iatrogenic SAN transection injury within the posterior cervical triangle were prospectively studied with high resolution US between December 2012 and November 2014
Patients also underwent a thorough neurologic examination and electrodiagnostic testing
Operative findings were correlated with the US results

4. Ultrasonographic Examination
Performed in the sitting position with the patient’s head turned to the contralateral side
The upper trapezius was identified with the transducer in an anatomic sagittal plane along the anterior edge of the trapezius (at the junction of the middle and lateral thirds)
The SAN branch to the trapezius was identified
A small (<1mm diameter) oval, hypoechoic structure emerging deep to the anterior edge of the upper trapezius
SAN was followed in short-axis proximally through the posterior cervical triangle to the posterior aspect of the sternocleidomastoid (SCM)

5. Ultrasonographic Examination
Findings were interpreted as either
“Transections”:
Direct visualization of discontinuity
Presence of terminal neuromas
Denervative changes in upper trapezius
“Probable”
Absence of sonographically documented nerve discontinuity and/or terminal neuromas
Tortuous course of SAN
Generalized enlargement of SAN

6. Sonographic Video

7. Results (History)
Six patients with clinically suspected iatrogenic SAN injures
Affected side: 4 right, 2 left
Hx of lymph node biopsy (n=5) or peripheral schwannoma removal (n=1)
Preoperative electrophysiologic studies showed severe neuropathy in all patients

8. Results (US/ IntraOp)
Time interval (injury to US): 8.4 months (2-17 mo)
Findings: 4 complete transection, 2 “probable”
Transection confirmed intraoperatively in all patients (n=6)
Tx: Direct repairs (n=4), interpositional nerve grafting (n=2)

9. Intraoperative Photos

10. Spinal Accessory Nerve
The SAN is formed by the fusion of cranial and spinal contributions
Enters the posterior cervical triangle from the posterior edge of the SCM, inferior to the junction of its upper and middle thirds
Within the triangle, the SAN courses deep to the superficial cervical fascia and adjacent to spinal accessory chain lymph nodes
This relationship leaves the SAN prone to injury

11. Spinal Accessory Nerve Injury
Injury within the posterior cervical triangle results in:
Trapezius weakness
Decreased shoulder abduction from scapular instability
Chronic shoulder pain and/or cosmetic disfiguration
A 3-6 month observation period is recommended prior to surgical exploration
In the setting of SAN transection, this observation period compromises patient’s outcome

12. Diagnostic Procedures
Electrodiagnostic examination is the most sensitive procedure in detecting nerve conduction impairment
Con: Unable to provide structural information
Voluntary motor unit potentials still noted in transected nerves due to cervical branch innervation
Imaging studies (US) may visualize nerve damage

13. Peripheral Nerve Sonography
Role of US in peripheral nerve injury imaging is well established
Provides quick, realtime evaluation
Studies using US have been able to accurately identify the course and variations of the SAN
Nerve injury and scar tissue may be easily identified as hypoechoic masses in the superficial layer of the posterior cervical triangle

14. Ultrasound in SAN Injury
US visualized SAN transection in 4 patients
In the remaining two patients, technical limitations precluded direct visualization
Enlarged lymph nodes
Extensive (dense) scarring
Surgical artifacts (staples, clips, etc)
Evaluating for secondary signs can aid in correctly diagnosing nerve transections
Denervation atrophy of the trapezius
Undulating SAN course
Generalized enlargement of SAN

15. Secondary Signs of SAN Injury

16. Conclusions
High resolution US shows great promise in the management of iatrogenic SAN injuries
Development of technique and operator training in the visualization of SAN transection lesions, US can improve patient outcomes
Identification of transected SAN early on by US will represent a paradigm shift in patient care by hastening surgical intervention

17. References
Wright TA: Accessory spinal nerve injury. Clin Orthop Relat Res 108:15-18, 1975.
Kim DH, Cho YJ, Tiel RL, Kline DG: Surgical outcomes of 111 spinal accessory nerve injuries. Neurosurgery 53: , 2003
Osgaard O, Eskesen V, Rosenorn J: Neurosurgical repair of iatrogenic accessory nerve lesions in the posterior triangle of the neck. Acta Chir Scand 153: , 1987
Norden A: Peripheral injuries to the spinal accessory nerve. Acta Chir Scand 94: , 1946
Camp SJ, Birch R: Injuries to the spinal accessory nerve: a lesson for surgeons. J Bone Joint Surg Br 93:62-67, 2011
Wiater JM, Bigliani LU: Spinal accessory nerve injury. Clin Orthop Relat Res 368:5-16, 1999
Chandawarkar RY, Cervino AL, Pennington GA: Management of iatrogenic injury to the spinal accessory nerve. Plast Reconstr Surg 111: , 2003
Bodner G, Harpf C, Gardetto A, et al: Ultrasonography of the accessory nerve: normal and pathologic findings in cadavers and patients with iatrogenic accessory nerve palsy. J Ultrasound Med 21: , 2002
Mirjalili SA, Muirhead JC, Stringer MD: Ultrasound visualization of the spinal accessory nerve in vivo. J Surg Res 175:e11-16, 2012
Canella C, Demondion X, Abreu E, Marchiori E, Cotten H, Cotten A: Anatomical study of spinal accessory nerve using ultrasonography. Eur J Radiol 82:56-61, 2013
Tubbs RS, Benninger B, Loukas M, Cohen-Gadol AA: Cranial roots of accessory nerve exist in the majority of adult humans. Clin Anat 27: , 2014
Laughlin RS, Spinner RJ, Daube JR: Electrophysiological testing of spinal accessory nerve in suspected cases of nerve transection. Muscle Nerve 44: , 2011

18. Questions & Discussion