Neck Dissections



10.1055/b-0034-79223

Neck Dissections

C. Piazza, F. Del Bon, P. Nicolai

Introduction


Neck dissections (NDs) include a wide spectrum of surgical procedures aimed at removal of different neck lymph nodes groups, distinguished in seven levels as proposed by the American Head and Neck Society and American Academy of Otolaryngology—Head and Neck Surgery.1 According to the same classification and its subsequent proposal for revision,1,2 ND can range from a very extensive and morbid procedure, such as extended radical neck dissection, passing through radical (RND) and modified radical (MRND) neck dissections, to less invasive ones such as selective or so-called superselective neck dissection (SND; aimed at targeted removal of two adjacent neck levels after nonsurgical organ preservation strategies).


Therefore, both the prevalence and severity of complications and sequelae of ND can vary greatly in relation to the type of procedure, and are diversely affected by several variables mainly in relation to their association with synchronous primary tumor removal, reconstructive surgical techniques adopted, and postradiotherapy (RT) or chemoradiotherapy (CRT) setting. Adverse events after ND may significantly impact the overall health and quality of life of head and neck cancer patients in both the short-term and long-term. Their anticipation in patient counseling, prevention, management, and evaluation play an essential role in such a demanding surgical intervention.



Complications Related to Skin Incisions


Different skin incisions for ND have been reported and may be chosen according to several criteria. The most important is certainly the potential need for associated tumor resection. In case of oral/oropharyngeal lesions, the incision should start from the mastoid process extending to the mid-third of the sternocleidomastoid (SCM) muscle, then reaching the midline of the submental level or chin ( Fig. 25.1 ). In the event of bilateral NDs, this incision goes from one mastoid process to the contra-lateral one, passing through the cricothyroid membrane ( Fig. 25.2 ). In case of parotid, auricular, or parapharyngeal lesions, a posterosuperior extension of the incision should be performed at the level of the preauricular or retroauricular region, while for thyroid, hypopharyngeal, or laryngeal primaries, a classic “apron” or “hemi-apron” flap is raised to include tracheotomy in the same incision as needed ( Fig. 25.3 ).

Skin incision used in case of unilateral selective neck dissection (levels I–III).
Skin incision used for bilateral selective neck dissection (levels I–III).

As a general rule, removal of neck lymph nodes from levels I to IV and VB can be easily accomplished through a horizontal incision from the posterior midthird of the SCM muscle to the cricothyroid membrane, while dissection of level VA usually needs a more posterior and caudal extension of the incision reaching the level of the supraclavicular fossa. Dissection of level VI and VII must be usually addressed through a skin flap involving the jugular notch. A thorough dissection from levels I to VII can be accomplished by the MacFee incision ( Fig. 25.4 ), which allows excellent cosmetic results at the price of a more tedious and time-consuming dissection. Apart from these variables, the general rules to be observed include performing horizontal more than vertical incisions for cosmetic reasons, and following whenever possible preexisting skin creases.

“Hemi-apron” or “hockey stick” incision.
MacFee incision.

Every neck scar or previous incision should be incorporated into the new one. When composite skin incisions are required, it is imperative to avoid acute angles at their intersection point. For this reason, we usually avoid skin incisions such as Martin double-Y, Schobinger, and H incisions. When this is not possible, the areas of potential skin devascularization and dehiscence should be placed away (usually posteriorly) from the major vessels. Every effort should be made to carefully plan such incisions, especially in patients with a previously irradiated neck because of their well-known higher propensity for cutaneous dehiscence and infection, with potential vascular exposure and blowout. Along the same lines, every care should be taken in patients with fragile tissues to protect the skin flaps during surgery, by gentle handling, applying moist gauzes or wet towels, and performing frequent saline irrigation, so avoiding intraoperative desiccation of the flap.


In spite of all these preventive measures, dehiscences at the level of the surgical wound may still occur ( Fig. 25.5 ). A limited gap can be managed conservatively by aggressive and frequent medication to stimulate healing by secondary intention. In case of more extensive flap necrosis with potential exposure of major blood vessels or associated local infection for fistula formation, regional pedicled or free flaps may be required. Hyperbaric oxygen therapy, especially in a previously irradiated and infected field, can play a role in this setting, both as an attempt to promote spontaneous healing, and in preparation of the following reconstructive procedure.3,4

Cutaneous dehiscence after surgery on a preirradiated neck. (Image courtesy of M. Bernal, MD.)


Locoregional Infections


Wound infections are more frequently encountered when ND is performed in association with upper aerodigestive tract procedures followed by development of oral/oropharyngeal or pharyngocutaneous fistulas. Moreover, previous RT or CRT may increase their prevalence by several fold ( Figs. 25.6 and 25.7 ). The most frequent cause of local infection after ND that is not associated with upper aerodigestive tract procedures is represented by formation of seroma or hematoma. This can be avoided by meticulous intraoperative hemostasis, placement of at least one suction drainage on each side of the neck, and control of its correct postoperative functioning. Frequently, poor functioning of suction drainage is related to inadequate suture around the tracheostomy site or along the incision itself. Early evaluation and solution of these problems are mandatory. When seroma or hematoma is suspected, it must be aggressively treated by drainage through a small opening of the previous suture or via a separate stab wound to prevent superinfection. If this develops, it is usually accompanied by sudden spiking fever, chills, malaise, increase in white cell count, odor, purulent discharge from the incision or from the drainage, edema and hyperemia of the skin flaps, and swelling at the level of the surgical field. Once infection is diagnosed, its management is based on broad-spectrum antibiotics, drainage of the wound, and, if wound breakdown occurs, covering of large vessels by a pedicled myofascial pectoralis major flap to obliterate the dead space. This is strongly suggested, especially in association with RND or major pharyngocutaneous fistula. Every effort should also be directed to the correction of possible predisposing factors like malnutrition, electrolytic alterations, and diabetes.

Pharyngocutaneous fistula after surgery on an irradiated neck. (Image courtesy of M. Bernal, MD.)

Prevention of local infections with a liberal use of antibiotics is still debated. While antibiotic prophylaxis for isolated ND in nonirradiated patients is not considered beneficial by most authors, the evidence for antibiotic prophylaxis in ND associated with upper aerodigestive tract opening and for patients previously undergoing RT or CRT is less clear-cut. Different antibiotics have been reported (penicillins with or without sulbactam, cephalosporins, clindamycin, metronidazole), with various associations, dose, and time of administration that are largely dependent on personal preferences and specific institutional policies. Patients treated by salvage surgery on the larynx, hypopharynx, and oropharynx with concomitant ND after failure of nonsurgical organ preservation strategies certainly require a more cautious approach.5,6



Complications Related to Lymphatic Vessels


Prevalence of lesions of the thoracic duct (during left ND) and right lymphatic duct (an inconstant and smaller structure formed by the union of the right jugular, subclavian, and bronchomediastinal trunks entering the neck across the medial border of the anterior scalenus muscle and leading to the junction of the right subclavian and internal jugular vein [IJV]), during clearance of level IV, is reported in around 1.5% of MRND7,8 and in 1 to 3% after RND.9 However, this figure is probably an underestimate of the actual prevalence of chylous leaks (CL), accounting 5.8% of cases.10 Of these, only ~ 25% occur on the right side of the neck.11

Local wound infection with partial necrosis after surgery on an irradiated neck. (Image courtesy of M. Bernal, MD.)

Predisposing factors are previous RT, which renders identification of lymphatic vessels difficult and makes their walls more fragile during surgical dissection, and some anatomic variations such as a more cranial ending of the thoracic duct (reported as high as 5 cm above the clavicle) or multiple terminations. Presence of large metastatic lymph nodes also seems to be associated with hypertrophy of the lymphatic drainage system, with an increased number of collectors identified during dissection and a higher risk of intraoperative injury.


The best treatment of CL is prevention by careful and bloodless dissection at level IV.9,12 In case of intraoperative injury of a lymphatic vessel, CL may be detected macroscopically as a milky, oily, partially transparent fluid. Not infrequently, it is possible to see the tear in the thoracic duct itself by using operating loops. Otherwise, to help in identifying the point of leak, the anesthesiologist may be asked to apply positive pressure ventilation, so raising central venous pressure.10 Placing the patient in the Trendelenburg position may also be useful, in addition to moderate external pressure on the abdominal wall.


A CL can be treated by ligation and oversewing of the bed of the thoracic duct with nonabsorbable suture, being careful not to further damage the thin-walled duct.10,13 In case of missed identification of the CL source, a tobacco pouch suture should be made in the possible area of origin. Various local and regional flaps have been described to primarily cover the CL site, ranging from the scalenus anterior muscle flap, which is not recommended because of the risk of damage of the brachial plexus, to the clavicular head of the SCM.12,14 During all of these surgical maneuvers, significant effort should be made to preserve both phrenic and vagal nerves. Various aids have been proposed to increase the likelihood of CL closure, including the use of fibrin glue or sclerosing agents. The main advice is against neck closure and patient awakening if the leakage is not completely controlled. Dietary modifications such as a low-fat diet should be initiated the day after surgery and continued for at least 7 days if a CL has been intraoperatively detected. Medium-chain triglycerides are recommended10,12,15 because they are absorbed directly into portal venous circulation, bypassing the lymphatic system.9 If this dietary restriction is not successful, total parenteral nutrition is warranted.10 It bypasses the normal breakdown of long-chain fatty acids in the small bowel, decreasing the amount of chyle production; but it requires central venous catheterization with possible complications. Suction drainage should be avoided whenever feasible on the CL neck side or removed as soon as possible.


Even after the best control of all visible leakage sites, patients with intraoperative CL still remain at high risk for postoperative leakage, which occurs in 25 to 75% of patients.9 This may not appear until several days after surgery (generally on the third postoperative day). Postoperative CL is manifested by unexpectedly high drain outputs, or by the appearance of creamy, greasy, oily, yellow-white fluid in the drainage. Differential diagnosis includes saliva if the ND was performed in association with surgery of the upper aerodigestive tract or major salivary glands. Confirmation of CL can be obtained by the analysis of the drainage content searching for amylases (in case of saliva) or triglycerides (in case of CL).


Postoperative CL should be promptly and aggressively addressed. Left untreated, it may give rise to other complications such as an intense inflammatory reaction, wound infection, and dehiscence with possible exposure of major vessels. Moreover, a long-lasting high-output CL may result in electrolyte disturbance.11 Conservative management is recommended in the case of CL less than 600 mL/day. It comprises bed rest in an anti-Trendelenburg position, removal of suction drainages allowing them to drain naturally, application of pressure dressing at the level of the supraclavicular region, and dietary management. This conservative management can be prolonged for many days, but in the case of planned postoperative RT, this approach is advisable for no more than 30 days.10 Reoperation at the CL site may be troublesome, and finding the leakage site can be facilitated by feeding the patient with heavy cream a couple of hours before surgery.9 After exploration of the surgical field, use of fibrin glue, mattress suture around the leakage site or even harvesting of myocutaneous pectoralis major or latissimus dorsi flaps can be useful in case of massive leakage or in patients with fragile tissue conditions (diabetes, post-RT scenario).


General consensus in the literature advocates prompt revision surgery in case of CL exceeding 600 mL/day (high-output CL) for 4 to 5 consecutive days. In these cases, a longer conservative approach is risky, and can lead to worsening of the patient′s general condition, associated with excessive granulation and scar tissue formation, which makes revision surgery even more troublesome.


Some controversies exist about the use of sclerosing and bonding agents such as tetracyclines in the management of postoperative persistent CL after failure of medical or surgical treatment. Of special note are concerns about outcomes, which seem to be late and unpredictable. It is certain that they are associated with intense local fibrosis that renders subsequent surgical revision technically more challenging.



Chylothorax


Chylothorax is a rare event after ND: as for CL the most affected site is the left one. The site of injury of the thoracic duct is usually unclear, and it is not possible to exclude that chyle extravasation in the chest is the result of backpressure after ligation of the main duct in the neck. In such a situation, chyle may pass through the cervical fascia, reaching the mediastinum and thoracic cavity. Another possible mechanism explaining chylothorax when macroscopic tearing of the pleura is not visible is progressive pleural infiltration and soaking because of the prolonged stagnation of chyle in the supraclavicular fossa. Following this, unilateral chylothorax could spread bilaterally by the same mechanism. Massive pleural effusion may cause cardiorespiratory failure as a result of mechanical compression on the lung and major thoracic vessels.


Therapy encompasses dietary restrictions and medical precautions as mentioned above for CL. Puncture and drainage of subcutaneous collection can be associated with one or more thoracenteses or left thoracostomy drainage. Pleurodesis via talc introduced into the pleural space through a chest drain to obtain a scar reaction and subsequent pleural obliteration is an alternative approach. Surgical revision should be left as the last option. Prognosis of this rare complication, when promptly recognized, is good and without major respiratory complications.



Lymphocele


Described as a circumscribed collection of fluid without an endothelial lining, lymphocele may develop as a late complication of CL. It is an extremely rare condition, even though it can be accidentally encountered during postoperative magnetic resonance follow-up ( Fig. 25.8a, b ). First described by Chantarasak and Green in 198916 as the consequence of a low-output CL into the healing tissues, lymphocele formation may be the result of the presence of a wall of scar tissue preventing the CL from spreading along the fascial layers into the adjacent anatomic compartments. Differential diagnosis with hematoma, seroma, abscess, nodal persistence, or recurrence with cystic degeneration is of paramount importance. Lymphocele usually appears as a taut-elastic swelling, generally located in the supraclavicular region, mostly on the left, in patients with a history of intraoperative or postoperative CL. Neck ultrasound is useful in identifying its fluid content and defining relationships with the IJV and subclavian vein, SCM, and deep neck muscles. Ultrasound-guided fine needle aspiration allows confirmation of the nature of the fluid, and temporary drainage of the fluid collection. Computed tomography and magnetic resonance imaging may be useful in the case of planned surgical revision.

a,b Magnetic resonance contrast-enhanced T1 sequence on axial (a) and coronal (b) planes. Lymphocele appears homogeneously hypointense with no contrast enhancement. It is located at the confluence of the subclavian vein with the internal jugular vein, medially displaced, and posteriorly in contact with the anterior scalenus muscle.

The treatment modality of lymphocele is not standardized in the literature because of its rare occurrence. However, it can be treated either by a conservative medical approach (drainage, local washing of the cavity by iodine solution, injection of sclerosing chemical agents like OK-432,17 application of compressive dressings in the supraclavicular region, and appropriate diet), or by surgical revision as described for CL.16,18



Complications Related to Blood Vessels



Internal Jugular Vein Blowout


Calearo and Teatini7 reported that the prevalence of IJV rupture was 0.8% after an MRND type III procedure. After unilateral RND, during contralateral ND this event can cause severe complications because of increased intracranial pressure. Intraoperative injury of the middle portion of the IJV can usually be controlled easily, while its tearing at the skull base or below the clavicle may be more troublesome, requiring, respectively, mastoidectomy with sigmoid sinus obliteration or clavicle disarticulation to properly control bleeding. Injury of the subclavian vein can also be associated with IJV damage, and its ligature may cause postoperative upper limb edema. Lesion of the IJV or a major collateral vessel may be complicated by fatal air embolism. To prevent this rare event, the patient should always be placed in a Trendelenburg position during the steps of ND in which the IJV is at risk.



Internal Jugular Vein Thrombosis


Even after SND, minor injuries to the IJV may occur causing its complete or partial thrombosis. Some factors responsible for this event are: complete mobilization of the vessel from the clavicle to the jugular foramen with its excessive handling and traction resulting in loss of vasa vasorum, inappropriate ligation of large side branches with formation of possible thrombogenic pockets, heat damage of the venous wall through an excessive use of monopolar cautery or bipolar forceps, and dehydration of the vessel wall, which is exposed to the air during long procedures. These technical factors are complemented by others, such as maintenance of inadequate intraoperative blood volume, reduction of blood flow, hypotension during surgery and in the immediate postoperative period, and a hypercoagulable state characteristic of some cancer patients because of an increase in factor VIII, the number of platelets, and their adhesiveness. Use of a bulky myocutaneous flap for reconstruction (causing compression of the IJV), salivary fistula, wound infection, and sepsis are other predisposing factors. The role of RT is still controversial. Diagnosis of IJV thrombosis may be easily made with high-resolution Doppler ultrasound, which allows a rapid, noninvasive, and accurate assessment of vein patency.1922 Computed tomography and magnetic resonance imaging are clearly more expensive, but can add information regarding anatomic structures surrounding the IJV.


Several studies have confirmed that IJV thrombosis may occur in up to 30% of patients within a week after MRND, with recanalization within 3 months between 60 and 80%, and vessel patency after surgery estimated to be around 95%.21,2330

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Jun 29, 2020 | Posted by in OTOLARYNGOLOGY | Comments Off on Neck Dissections
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