Dual spinal accessory nerve: caution during neck dissection.

Preserving the spinal accessory nerve (SAN) is an important step in the modern-day neck dissection to avoid postoperative functional morbidity in patients. This goal can become technically difficult, especially, when rare anatomical variations are encountered. We present a case of dual SAN in a patient undergoing selective neck dissection for oral squamous cell carcinoma. Both SANs were preserved and patient had no shoulder dysfunction postoperatively. We take this opportunity to emphasise that meticulous dissection is the only proven way to preserve the nerve. And that surgeons should be aware of this anatomical variation. SAN should be subjected to minimal traction during neck dissection to avoid tension neuropraxia and long-term shoulder dysfunction.

Ultrasonic identification of internal jugular vein fenestration.

OBJECTIVE: Anatomic variations have curicial importance during neck surgery. We present a fenestrated internal jugular vein variation and the accessory nerve passing through it. Also, we discuss preoperative diagnosis of this variation using ultrasonography. METHOD: The possible recognition of this variation by ultrasonography is introduced. RESULTS: The accessory nerve in an internal jugular vein fenestration can be seen using ultrasonography. CONCLUSION: Preoperative identification of this rare variation may secure surgeon from potential complications.

Intraoperative Brief Electrical Stimulation of the Spinal Accessory Nerve (BEST SPIN) for prevention of shoulder dysfunction after oncologic neck dissection: a double-blinded, randomized controlled trial.

BACKGROUND: Shoulder dysfunction is common after neck dissection for head and neck cancer (HNC). Brief electrical stimulation (BES) is a novel technique that has been shown to enhance neuronal regeneration after nerve injury by modulating the brain-derived neurotrophic growth factor (BDNF) pathways. The objective of this study was to evaluate the effect of BES on postoperative shoulder function following oncologic neck dissection. METHODS: Adult participants with a new diagnosis of HNC undergoing Level IIb +/- V neck dissection were recruited. Those in the treatment group received intraoperative BES applied to the spinal accessory nerve (SAN) after completion of neck dissection for 60 min of continuous 20 Hz stimulation at 3-5 V of 0.1 msec balanced biphasic pulses, while those in the control group received no stimulation (NS). The primary outcome measured was the Constant-Murley Shoulder (CMS) Score, comparing changes from baseline to 12 months post-neck dissection. Secondary outcomes included the change in the Neck Dissection Impairment Index (ΔNDII) score and the change in compound muscle action potential amplitude (ΔCMAP) over the same period. RESULTS: Fifty-four patients were randomized to the treatment or control group with a 1:1 allocation scheme. No differences in demographics, tumor characteristics, or neck dissection types were found between groups. Significantly lower ΔCMS scores were observed in the BES group at 12 months, indicating better preservation of shoulder function (p = 0.007). Only four in the BES group compared to 17 patients in the NS groups saw decreases greater than the minimally important clinical difference (MICD) of the CMS (p = 0.023). However, NDII scores (p = 0.089) and CMAP amplitudes (p = 0.067) between the groups did not reach statistical significance at 12 months. BES participants with Level IIb + V neck dissections had significantly better ΔCMS and ΔCMAP scores at 12 months (p = 0.048 and p = 0.025, respectively). CONCLUSIONS: Application of BES to the SAN may help reduce impaired shoulder function in patients undergoing oncologic neck dissection, and may be considered a viable adjunct to functional rehabilitation therapies. TRIAL REGISTRATION: Clinicaltrials.gov ( NCT02268344 , October 17, 2014).

Spinal accessory nerve preservation in modified neck dissections: surgical and functional outcomes.

The spinal accessory nerve (SAN) or XI cranial nerve is frequently encountered during neck surgery, and as such is at risk of iatrogenic injury, resulting in "shoulder syndrome". Modified neck dissection (MND) with preservation of the SAN is based on desire to minimise the functional deformity associated with section of the eleventh nerve. The aim of this study was to analyse the intra-operative variations of the spinal accessory nerve pathway and to evaluate shoulder dysfunction postoperatively. The cross-sectional demonstration analysis was created through the medical records retrospectively of 165 consecutive patients who underwent neck dissections at our institution in the past 5 years with attention to ultrasound and MRI preoperative findings, type of neck dissection, type of identification and dissection of SAN, postoperative morbidity and survival rate. The safest identification of SAN is in the posterior neck triangle where it may be recognised exiting from the posterior border of the sternocleidomastoid muscle (SCM) at Erb's point. For exact preoperative planning, ultrasound and MRI are superior to determine the position of the eleventh nerve. The mean distance between the greater auricular point and the SAN was 0.90 cm. Average length of the trunk from Erb's point until the penetration in the trapezius muscle was around 5.1 cm, ranging from 4.8 to 5.4 cm. The diversity in the course from the posterior border of the SCM and posterior neck triangle was confirmed in 9 cases (15%), predominantly at the level of entering the posterior neck triangle. The frequency of postoperative morbidity of SAN was 46.7% for radical neck dissections, 42.5% for selective neck dissections and 25% for MND. For each separate type of dissection, different subtypes were included. Identification of the SAN over established landmarks is unconditionally reliant on the exact preoperative mapping of the nerve with imaging diagnostics. MND has similar regional control rates to more comprehensive operations in appropriately selected patients and significantly reduces the risk of functional disability.

Different branching patterns of the spinal accessory nerve: impact on neck dissection technique and postoperative shoulder function.

PURPOSE OF REVIEW: Despite nerve-sparing surgery, postoperative shoulder morbidity remains high and significantly impacts patient's quality of life. This review will focus on recent findings of anatomical nuances of the cranial nerve XI (CN XI) along its course in the neck and possible reasons for postoperative morbidity. RECENT FINDINGS: The most recent studies identified three different branching patterns of the CN XI in the neck. In type 1 (66%), the branch for trapezius muscle exits at the posterior border of the sternocleidomastoid muscle (mSCM). In type 2 (22%), the branch for trapezius muscle takes off from the common trunk of the CN XI before it enters the mSCM. In type 3 (12%), the motor branch for trapezius muscle exits behind posterior border of mSCM but takes a more medial course to form macroganglia with cervical nerves. Cervical nerves may also contribute to innervation of the trapezius muscle in up to 39% of the cases, but the clinical importance of those connections is not known. SUMMARY: If these anatomical patterns are not recognized and if cervical nerves are resected during neck dissection, shoulder morbidity remains high. The role of cervical nerves in innervation of the trapezius muscle is still controversial and unpredictable.

An anatomic-based approach to the iatrogenic spinal accessory nerve injury in the posterior cervical triangle: How to avoid and treat it.

Iatrogenic injury of the spinal accessory nerve (SAN) is a significant reducible risk with any invasive procedure involving the posterior cervical triangle. Most commonly associated with cervical lymph node biopsy, it affects 3-6% of patients and serves as a major cause of avoidable medical malpractice litigation. Medical malpractice cases not only affect the primary surgeon but also may include the repairing surgeon through a shift of blame. For this reason, we discuss the strategies all clinicians may utilize in approaching iatrogenic SAN injuries. By taking basic precautionary measures based on simple application of anatomy in the management of these patients, clinicians may protect themselves from needless malpractice litigation. A thorough knowledge of the anatomy and application in preventative strategies may provide guidance for clinicians in reducing the incidence of iatrogenic injuries, providing effective postinjury management, and ensuring the salvaging surgeon is not at fault if litigation is pursued.

Diagnostic accuracy of cone-beam CT compared with panoramic images in predicting retromolar canal during extraction of impacted mandibular third molars

OBJECTIVES: The clinical significance of the existence of a retromolar canal and of its neurovascular content is not yet clear. The aim of the present study was to assess the visibility, diameter and course of the mandibular retromolarcanal(MRC) using cone beam computed tomography (CBCT) scan -had been taken for pre-operative radiographic evaluation of impacted mandibular third molars- compared to panoramic radiographs. Study DESIGN: Subjects eligible for study enrollment were those who underwent preoperative CBCT scan for the extraction of impacted mandibular third molars were determined to be extremely close to the mandibular canal on panoramic radiographs. Radiographs were screened for the presence and course of retromolar canals, and linearmeasurements. RESULTS: 947hemimandibles in 632 patients were examined. A total of 253 MRCs (144 left, 109 right) were detected with CBCT images (26.7%). Only 29 of these canals were also seen on the corresponding panoramic radiographs. Most MRCs had a vertical course (type VI, 28.46%), followed by slightly curved (type I, 26.09%). The visibility of the MRC on the OPGs, according to the increase in the diameter, was not statistically significant for both sides(p >.05).Statistically difference were found for the width at the point of origin from the mandibular canal (p: .037),the mean distance from the MRC to the second molar (p: .042) and height of MRC when compared the gender. CONCLUSIONS: The findings suggest that the MRC isn't a rare anatomical structure. This study therefore clearly establishes the incidence and importance of the MRC. The detection of the presence of the MRC using CBCT maybe crucial for extraction of mandibular third molars

Intra-operative monitoring of the spinal accessory nerve: a systematic review.

OBJECTIVE: To investigate evidence that intra-operative nerve monitoring of the spinal accessory nerve affects the prevalence of post-operative shoulder morbidity and predicts functional outcome. METHODS: A search of the Medline, Scopus and Cochrane databases from 1995 to October 2012 was undertaken, using the search terms 'monitoring, intra-operative' and 'accessory nerve'. Articles were included if they pertained to intra-operative accessory nerve monitoring undertaken during neck dissection surgery and included a functional shoulder outcome measure. Further relevant articles were obtained by screening the reference lists of retrieved articles. RESULTS: Only three articles met the inclusion criteria of the review. Two of these included studies suggesting that intra-operative nerve monitoring shows greater specificity than sensitivity in predicting post-operative shoulder dysfunction. Only one study, with a small sample size, assessed intra-operative nerve monitoring in neck dissection patients. CONCLUSION: It is unclear whether intra-operative nerve monitoring is a useful tool for reducing the prevalence of accessory nerve injury and predicting post-operative functional shoulder outcome in patients undergoing neck dissection. Larger, randomised studies are required to determine whether such monitoring is a valuable surgical adjunct.