11 Complications of Neck Dissection

The excellent blood supply of the neck limits the rate of wound infection and dehiscence. In the absence of communication with the aerodigestive tract, neck dissection is a clean procedure and carries a wound infection rate of approximately 1%. This increases considerably when the aerodigestive tract is entered, with studies showing surgical site infection (SSI) rates (as strictly defined by the Centers for Disease Control and Prevention [CDC]) of between 3 and 41%.^1,2 Antibiotic prophylaxis can decrease this risk to about 13%.¹ Multiple antibiotic combinations have been tested, with the most common being cefazolin for clean procedures, and ampicillin-sulbactam for clean-contaminated. Clindamycin alone has been shown to be inferior to ampicillin-sulbactam, and it is recommended to add gram-negative coverage for patients who are allergic to penicillins.^3,4 Duration of antibiotic prophylaxis longer than 24 hours does not correlate with improvement in SSI rate.^5,6,7 Multiple factors have been shown to increase risk of SSI including medical (hypothyroidism, diabetes, smoking, methicillin-resistant Staphylococcus aureus colonization, hypoalbuminemia, history of previous radiation therapy) and surgical (operative time, operative blood loss, flap failure, operative takebacks, concomitant tracheostomy, osteocutaneous free flaps).^8,9,10 When possible, these should be addressed to reduce the risk of infection.

Wound dehiscence is often closely related to wound infection; however, it can occur primarily. Careful attention to incision planning, particularly in the case of previous surgery or radiation, is critical to avoid flap loss and subsequent dehiscence. Avoiding trifurcated incisions when possible, gentle tissue handling, subplatysmal dissection, meticulous closure, and elimination of dead spaces are all technical considerations that reduce the risk of wound complications. Similarly, avoidance of excess tension on the skin—particularly if skin is resected with the specimen—is mandatory to avoid diminished vascularity and secondary tissue loss.

11.3 Vascular Complications

11.3.1 Hemorrhage

Bleeding complications after a neck dissection typically cause issues related to local compression, rather than loss of blood volume and resultant hemodynamic instability. Hematomas typically develop in the immediate postoperative time frame, but there are reports of patients presenting 1 week postoperatively with acute hematomas requiring surgical treatment. Most hematomas should be managed with exploration in the operating room with control of any offending vessels. The overall incidence of postoperative hematoma after neck surgery is estimated to be 1 to 1.7%.¹¹

Patients may develop difficulty breathing when a hematoma expands, and causes venolymphatic obstruction that leads to supraglottic edema ( Fig. 11.1). For this reason, once a hematoma is identified, it should be managed expediently, and, occasionally, bedside drainage is necessary to prevent upper airway obstruction if patients show signs of respiratory distress. The airway should be secured as soon as an expansile hematoma is identified.

Hematomas are best avoided by ensuring meticulous hemostasis during the dissection and prior to closing the wound. Many surgeons evaluate for bleeding using intraoperative Valsalva maneuver or Trendelenburg tilt. Several studies have shown that these maneuvers identify small bleeding points, but their use does not correlate with a reduction in hematoma formation.^12,13

Numerous attempts have been made using specialized instruments (e.g., Harmonic scalpel) or hemostatic products to decrease intraoperative bleeding, and reduce rate of hematoma. Studies have shown some nonclinically significant improvement in intraoperative bleeding and postoperative drainage, but unfortunately are underpowered to detect differences in hematoma rates.^{14,15,16,17,18} Proper patient selection, meticulous surgical technique, and thorough hemostasis are still the best practices for preventing postoperative hematoma.

Arterial spasm may also deceive the surgeon intraoperatively. Thus, it is advisable to routinely examine the superior thyroid, occipital, transverse cervical, and facial arteries at the end of a case if the nodal packets near these vessels were dissected.

Another rare but potentially serious bleeding complication can arise during a neck dissection if the patient has a tortuous carotid artery that results in a laterally displaced segment of carotid artery.¹⁹ This can be particularly prominent in elderly patients ( Fig. 11.2). Such a segment of distorted carotid artery is prone to injury when dissecting the lateral nodal contents off the transition point between the floor of the neck and the carotid sheath. Vascular injury in these cases may be avoided by routinely reviewing the preoperative CT scan. Injury to the carotid artery during a neck dissection may result in life-threatening blood loss and stroke.

Fig. 11.1 Edematous false vocal folds and partially obstructed airway in a patient being intubated due to airway compromise caused by a neck hematoma.

Fig. 11.2 (a) A tortuous segment of internal carotid artery (white arrow) is noted after a left neck dissection. This knuckle of artery may be mistaken for a prominent lymph node if care is not taken. (b) CT angiogram of a different patient with a more extreme example of an ectatic internal carotid artery (white arrow) on the left. (Image b reproduced with permission of Agarwal G, Gupta A, Chaudhary V, Mazhar H, Tiwari S. Rare anatomical variant of the cervical internal carotid artery. Br J Oral Maxillofac Surg 2017;55:530–532.)

Internal jugular vein (IJV) blowout has been reported and is usually associated with circumferential dissection of the vessel, desiccation of the vessel adventitia, and/or a concomitant salivary fistula.²⁰ This is a low-pressure system; therefore, bleeding is typically not florid, but it may be intermittent and associated with increased venous pressure as it occurs with coughing. At the time of surgical intervention, the carotid sheath should be carefully inspected, and consideration given to flap coverage in the context of a salivary fistula, as this situation also puts the carotid at risk of blowout.

11.3.3 Carotid Blowout Syndrome

This is defined as rupture of the carotid artery or branches caused by tumor involvement of the vessel, or as a result of late radiation toxicity. The level of severity is further subdivided in- to three clinical syndromes: threatened blowout, which refers to a clinically exposed vessel or radiologic evidence of tumor invasion to the vascular structure; impending blowout, when a herald bleed has settled spontaneously; and acute carotid blowout syndrome, with profuse, uncontrollable bleeding. When a carotid artery blowout is suspected, the surgeon typically has little time to act and mobilize resources. Radiation treatment and, particularly, re-irradiation place patients at increased risk of carotid blowout. Other contributing factors include a history of a neck dissection (particularly a radical neck dissection), fistula, devitalized soft tissue overlying the carotid, and cancer overlying or encasing the carotid.

Since survival is not guaranteed after developing this severe complication, extreme measures must be employed in managing it. This typically involves placing constant digital pressure over the area of hemorrhage, mobilizing a code team to actively start resuscitation while transporting the patient to the operating room, or to the interventional radiology suite, to ligate, bypass, stent, or embolize the carotid artery. In the case of operative intervention, the finger is prepped into the field and continuous pressure is maintained while wide exposure is obtained. If available, vascular surgeons may be of great assistance in managing this complex surgical scenario. More recently, excellent results have been obtained using endovascular stenting of the carotid artery.^21,22

In patients with a known substantial risk of carotid blowout (e.g., patient with unresectable carcinoma encasing the carotid, with contiguous disease involving the skin or pharynx), a frank discussion should be undertaken with the patient regarding this often-fatal complication and the potential role of prophylactic endovascular intervention. Advanced directives should be strongly encouraged for these patients.

11.4 Neurologic Complications

11.4.1 Stroke

Stroke is a rare, but functionally devastating complication of neck dissection. The risk of stroke in older series ranged as high as 4.8%. These studies, however, were retrospective and did not account for variables such as smoking, which is also correlated with the risk of stroke.

In a systematic review of NSQIP (National Surgical Quality Improvement Program) data, Cramer et al reported an increased risk of stroke following a neck dissection in patients with at least two carotid artery stenosis (CAS) risk factors (age older than 65 years, smoking, diabetes mellitus, hypertension, congestive heart failure, renal failure, history of stroke or transient ischemic attack).²³ The risk for such patients was measured at 2.86% for bilateral neck dissections, 0.41% for unilateral neck dissection, and 0.24% for no neck dissection. Additionally, stroke was significantly associated with 30-day mortality (7.4%). Another large database study from Canada showed a similar stroke rate in 30 days following surgery (0.7%) as compared to non–head and neck major surgery. Similar risk factors were identified, but the data were not reported separately for the high-risk group.²⁴ Additionally, the authors found a significant decrease in incidence from 1995 to 2012 (1.1–0.3%).

In patients with carotid artery disease, or risk factors for CAS, extra care should be taken to avoid retraction of the carotid sheath, and unnecessary manipulation of the carotid. If a very high-grade stenosis is identified on imaging, consideration can be made for preoperative endarterectomy, with careful consideration of the risk in the oncologic context.

11.4.2 Spinal Accessory Injury

Spinal accessory nerve injuries are best avoided by understanding not only the anatomic relationships of the nerve within the neck, but also that many patients with shoulder dysfunction after a neck dissection have an anatomically intact nerve. While the rate of unintended transection of the spinal accessory nerve is exceedingly low in experienced hands, the rate of shoulder syndrome after radical neck dissection is estimated to be 47 to 100%.²⁵ In addition, careful evaluation of shoulder function after neck dissection shows an approximately 20% reduction in function following a selective neck dissection, and up to 50% reduction following a modified radical neck dissection (with dissection of spinal accessory in level V as well). A program of physical therapy in the postoperative period is helpful in reversing weakness and postoperative pain, and it is routinely offered to patients after neck dissection at many institutions.^26,27

Injury to the spinal accessory nerve during a neck dissection may result from excessive traction and/or devascularization of the nerve. Direct traction on the nerve with a retractor should be avoided at all times during the procedure. If needed, a retractor may be placed on the sternocleidomastoid muscle (SCM) immediately cranial or caudal to the insertion of the spinal accessory nerve. Devascularization of a segment of the nerve is often difficult to avoid during dissection of level IIB (in addition to level IIA).²⁸ Bipolar electrocautery or cold techniques are best used near the nerve to avoid thermal injury as well. An additional area of concern for spinal accessory injury is in the posterior triangle of the neck, where the nerve is very superficial and can be injured while raising the skin flaps. Furthermore, in this area the nerve tends to be tortuous and may have a branching pattern, so meticulous attention to its meandering is critical to avoid injury.

Technically, the nerve is easily identified in the carotid triangle by slowly unwrapping the fascia of the SCM. The tendinous portion of the SCM is superficial to the nerve. The occipital perforating vessels supplying the upper portion of the SCM are found immediately superficial to the nerve ( Fig. 11.3). The bony landmark for the point where the nerve intersects with the IJV is the transverse process of the atlas, or C1.²⁹ Typically, the nerve traverses the IJV superficial—or lateral—to the vein (40–96%).³⁰ Occasionally, the nerve crosses deep—or medial—to the nerve (3–57%), and, rarely, the nerve courses through a fenestrated or bifurcating vein ( Fig. 11.3). There is even a report of the nerve splitting around the vein.²⁷ Given the variable relationship between the spinal accessory nerve and the IJV, it is prudent that surgeons be aware of this variability to avoid unnecessary injury to the IJV or spinal accessory nerve.

Dissection of level V places the nerve at increased risk due to its superficial course in this location. A firm grasp of the surgical planes and the course of the nerve in the posterior triangle is key to avoid injury. Identifying the anterior border of the trapezius is most helpful, since the nerve typically courses 1 to 2 cm inferior and parallel to this landmark. The nerve typically enters the anterior surface of the trapezius 2 to 5 cm superior to the clavicle. Along the posterior border of the SCM, the spinal accessory nerve is located typically within 1 cm superior to Erb’s point.²⁹

11.4.3 Marginal Mandibular Nerve Injury

The marginal mandibular nerve (MMN) is most relevant during a level I neck dissection, and to a lesser extent during access to the superior limit of level II. This branch of the facial nerve is responsible for innervating the depressors of the lower lip: the depressor anguli oris and depressor labii inferioris muscles. The consequence of the injury is an asymmetric smile, as well as some perceived difficulty with drinking and eating.³¹

Fig. 11.3 (a) Right spinal accessory nerve identified immediately deep to the perforating occipital vessels supplying the superior sternocleidomastoid muscle. (b) Rare example of a spinal accessory nerve traversing between a fenestrated internal jugular vein. (Reproduced with permission of Tatla T, Kanagalingam J, Majithia A, Clarke PM. Upper neck spinal accessory nerve identification during neck dissection. J Laryngol Otol 2005;119:906–908.)

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