Chylous Fistula of the Neck 

Updated: Sep 11, 2018
Author: Philip E Zapanta, MD, FACS; Chief Editor: Arlen D Meyers, MD, MBA 

Overview

Background

Damaging or cutting a thoracic duct while operating low on the left side of the neck does not occur infrequently, even in experienced hands. In fact, transecting the duct when carrying out radical surgery low down in the neck or the mediastinum may often be necessary. What should be avoided, however, is the failure to recognize this complication at the time of surgery, which could lead to serious consequences.[1]

See the image below.

Intraoperative photo of the thoracic duct low in t Intraoperative photo of the thoracic duct low in the neck on the left.

History of the Procedure

The first description of a cervical chylous fistula was in 1875 by Cheever, followed by Stuart in 1907 with the first review on the condition. At the time, this condition was managed merely with pressure dressings and wound packing, and mortality rates of up to 12.5% for cervical chylous fistula were reported.[2, 3, 4]

Problem

Chylous fistulas are known to lead to prolonged hospitalization. Clinically, chylous fistulas may be difficult to manage because of significant electrolyte, fluid, and protein abnormalities that are associated.

Epidemiology

Frequency

Chylous fistula is an infrequent complication of head and neck surgery, with an incidence reported in 1-3% of patients undergoing major neck surgery.[4] This condition has a predilection for the left side of the neck, but up to 25% of cases involve the right side of the neck.

Etiology

Radical neck dissection is the most frequent operation associated with chylous fistulas, but chylous fistulas may be found after selective neck dissection, penetrating neck trauma, cervical node biopsy, cervical rib resection, anterior neck surgery, and central venous cannulation.[5, 6]

Pathophysiology

The thoracic duct is the conduit for lymph and dietary fat to reach the venous bloodstream. The flow of chyle is around 2-4 L per day and consists of fat, protein, electrolytes, and lymphocytes.[4, 5, 7, 8] Its daily production is dependent on the diet and daily dietary intake.

Chemical composition of chyle is similar to that of tissue lymph, with higher concentration of cholesterol, phospholipids, and fat particles, particularly triglyceride rich chylomicrons and long-chain (>10 carbon atoms) esterified fats.[9]

The flow of chyle against gravity is supported by the interplay of thoracic and abdominal pressures, the transmission of peristaltic bowel contractions, the contraction of the lymphatic vessels walls, and the Venturi effect at the junction of the thoracic duct and the subclavian vein.[10]

Presentation

Patients with a chylous fistula present with drainage of "milky white" fluid; however, in patients who are nil by mouth or on a fat-free diet, it may present as a leakage of clear fluid. The volume of drainage ranges from low output (< 500 mL/day) to more than 3 L per day in high-output fistulas. Persistent chyle loss leads to electrolyte disturbance, hypovolemia, hypoalbuminemia, coagulopathy, immunosuppression, chylothorax, peripheral edema, wound infection, and local skin breakdown. Prolonged chyle leak can therefore lead to mortality.[11]

Indications

Indications for surgical intervention in patients with cervical chylous fistula remain unclear. A chyle leak identified intraoperatively warrants immediate repair. Success of surgery declines in the postoperative period because of fibrosis and the effect chyle has on the soft tissue of the neck. However, failure of medical therapy and radiological intervention advocates neck exploration or ligation of the thoracic duct, particularly in patients with high-output fistulas.

Relevant Anatomy

The thoracic duct is the largest lymphatic vessel in the body, transporting lymph and chyle from lower limbs, the abdomen, the left hemi thorax, and the left side of the head and neck to venous circulation. It originates anterior to the body of second lumbar vertebra, the cisterna chyli, and ascends, along the right side of vertebral column, through the aortic hiatus of the diagram into the posterior mediastinum, traveling between the aorta and azygous vein towards the fifth thoracic vertebra, where it crosses to the left and continues to ascend up into the neck.

In the neck, the thoracic duct raises 3-5 cm above the clavicle before arching back toward the junction of the left subclavian vein with the left internal jugular vein. Intraoperatively, the thoracic duct can be identified as it courses anterior to the vertebral and thoracocervical vessels between the internal jugular vein and the anterior scalene muscle.

The anatomical variability of its course in the neck makes it susceptible to iatrogenic injury. Cadaveric studies have shown variation of both the site of termination and the number of terminal branches. (See the images below.)[9, 12, 13]

Intraoperative photo of the thoracic duct low in t Intraoperative photo of the thoracic duct low in the neck on the left.
Thoracic duct inserting at the junction of interna Thoracic duct inserting at the junction of internal jugular and subclavian vein in a cadaveric specimen.

Contraindications

No absolute contraindications to surgical repair of cervical chylous fistula exist.

 

Workup

Laboratory Studies

Chyle has unique chemical characteristics that enable easy and accurate diagnosis. It has a high concentration of chylomicrons with high triglyceride (>5 g/L) and low cholesterol concentrations. Furthermore, chyle stains with lipophilic dyes, such as Sudan III, and when mixed with 1-2 mL of ethyl ether, chyle turns from milky to clear fluid.

Imaging Studies

Radiograph

Chest radiographs in patients with chylous fistula can demonstrate a soft-density opacity at the root of the neck. Chylothorax is an uncommon complication of chylous fistula and may be seen on chest radiographs as a pleural effusion.

CT scanning

CT scanning is used to confirm the presence, site, and extent of a neck collection. However, it is not useful for accurate localization of the thoracic duct injury.

Lymphangiography

Lymphangiography is an invasive procedure used to visualize the lymphatic vessels and thoracic duct as well as to identify the site of a chyle leakage. It requires catheterization of afferent lymph vessels in the foot and is associated with adverse effects such as local tissue necrosis, fat embolism, lymphoedema, and hypersensitivity reaction.

Lymphoscintigraphy

The use of nuclear medicine to identify the site of chyle leakage following thoracic duct injury has become increasingly popular. Lymphoscintigraphy is a quick, noninvasive technique that involves the administration of oral and intravenous water-based radionuclide, the flow of which is traced with a gamma camera or proton-emission scanner. Computer analysis of the data creates images of the lymph flow and determines the speed of uptake, allowing localization of the site of chyle leakage.[14, 15]

Direct Visualization

Leaks are typically low volume thus making identification difficult. If an intraoperative leak is suspected, the anesthesiologist may apply positive pressure, similar to the Valsalva maneuver, thus increasing intra-abdominal pressure and the flow of the leak. Alternately, manual abdominal compression may be applied.[16]

 

Treatment

Medical Therapy

Prevention is widely believed to be the optimum management for a chylous fistula. Once a chylous fistula has occurred, medical management focuses on measures to reduce chyle flow, with closure of the fistula as a result. This should be done while paying close attention to the patient's nutritional status.

Two different conservative postoperative management techniques have been proposed: (1) drain removal and aspiration and (2) negative pressure wound therapy (NPWT). The use of adjunctive somatostatin therapy has also been suggested. Data does not delineate the exact parameters for the use of these techniques.

Drain removal and aspiration has been shown effective in low-output fistulas with surrounding healthy tissue. Utilizing this technique, postoperative drains remain on continuous suction, a pressure dressing is applied, and bed rest is prescribed. Once chyle production plateaus, the drains are removed, and serial aspirations are performed.[17]

NPWT involves reopening the surgical incision, covering the wound with a sealant, and applying subatmospheric pressure. This technique has also proven successful in the management of low-output chylous fistulas. Caution should be taken to avoid rupture of major local blood vessels when NPWT is applied to the head and neck region.[18]

Somatostatin is a promising and novel method to treat chyle leaks. This hormone acts through various endocrine and paracrine pathways to reduce chyle production. Although most reports detail somatostatin’s adjunctive use in low-flow leaks,[19] Barilli et al reported success in a high-flow chyle leak.[20]

A retrospective study by Swanson et al indicated that octreotide therapy is a safe and effective treatment for chylous fistulas of the neck. Fistula resolution occurred in all 12 of the study’s patients after a mean 5.5 days.[21]  A retrospective study by Chan et al also found evidence that chylous fistulas can be effectively managed with octreotide, reporting that the therapy, combined with total parenteral nutrition, was successful in controlling chyle leakage in eight of the study’s 10 patients (80%).[22]

A retrospective study by Wei et al reported local treatment using Pseudomonas aeruginosa injection to be effective against intractable cervical chylous fistula. The study included 18 patients, all of whom were successfully treated with the therapy.[23]

Regardless of the treatment method employed, consulting with a nutritionist or dietitian is critical. An elemental feed with supplemented medium chain triglycerides may be used enterally. Total parenteral nutrition is the next step, but the timing of its use still remains unclear. Concerns about central venous access, infection, and cost have to be weighed against shorter duration of therapy, higher closure rates, and improved nutritional response. Hehar et al (2001) recommended that total parenteral nutrition should be used in a leak of less than 500 mL per day if it persists beyond 5 days.[24]

Surgical Therapy

Chyle leaks may be identified intraoperatively or postoperatively, as previously detailed. In the event of intraoperative chyle leak during dissection of the left lower neck, the leak should be repaired with nonabsorbable 3-0 or 4-0 sutures and an overlying material. Fibrin sealant, collagen felt, polyglactin 910 mesh, and muscle flaps have been suggested The sutures should be placed to include some of the surrounding tissues without penetrating the duct wall.[25, 26, 27] If possible, functional repair of the thoracic duct injury should be attempted rather than use of an approach that obliterates the thoracic duct, as the latter can produce distal complications.[28]

Despite intraoperative measures, a chyle leak may persist postoperatively, mandating secondary repair, embolization or ligation.

Preoperative Details

The decision to explore a patient's neck because of a chyle leak and the timing of it is still controversial. A step-wise approach is sensible, with surgery undertaken only after failure of medical treatment. Surgery was advised by Kassel et al in each of the following cases:[29]

  • More than 500 mL of drainage per day persisted after 1 week of medical treatment.

  • Persistent low-output drainage occurred over a prolonged period.

  • Complications developed.

Spiro et al found that if the peak 24-hour drainage was greater than 600 mL, medical management was likely to be unsuccessful.[30]

Although the aforementioned criteria can assist in identifying patients who would benefit from surgical intervention, a comprehensive, algorithmic approach to the type of surgical repair that should be performed does not exist at this time. Direct repair, thoracic duct embolization, therapeutic lymphography, thoracic duct ligation, and microsurgical lymphatic venous anastomosis are potential repair options. It has been suggested that functional repair is preferable to ligation, as distal lymph flow complications are possible.[28] Thus, ligation and embolization should typically be reserved for difficult-to-locate or massive leaks.

Intraoperative Details

Reexploration of the neck needs to be undertaken by an experienced head and neck surgeon, as severe inflammation is likely to be present at this stage. Once the previous incision has been opened, the subplatysmal flaps should be lifted and retracted to gain access to the lower neck. Gier et al used fibrin sealant and a pectoralis myofascial flap, without trying to find the leak, although targeted repair of an obvious leak is sensible.[30]

Velegrakis et al used a fibrin adhesive set, a 2-component sealant.[31] This combines fibrinogen, plasma fibronectin, factor XIII, and plasminogen in component A with aprotinin in component B.

Sclerosing agents like tetracycline and talc powder were advocated by Kassel et al.[8] Doxycycline sclerotherapy has been used, but a case report of phrenic nerve paralysis was followed by further work showing the neurotoxicity of doxycycline.[32, 33] Lymphangiography with lipiodol compounds also has occluding properties, but there is the possibility of an anaphylactic reaction. Thus, side effects have limited the use of sclerotherapies.

Embolization of the thoracic duct has also been described.[34, 35, 36] Research indicates that this technique has a 70-75% clinical success rate and that it has the greatest efficacy in patients with a chyle leak volume of less than 1 L.[37]

Ligation of the thoracic duct is an option for massive leaks or if other treatment options fail. Thoracoscopic ligation of the thoracic duct is the currently favored minimally invasive approach; this technique avoids an open right thoracotomy and its associated complications.[38, 39]

Lymphatic venous anastomosis is an effective, but technically demanding, repair technique. It perseveres the function of the thoracic duct but requires microsurgical equipment and expertise.[40, 41]

Postoperative Details

Continued vigilance is important because the chyle leak may persist. Continued attention should be paid to the management of electrolytes, nutritional status, and the wound. Infection may be difficult to distinguish from inflammation locally, and antibiotic prophylaxis is desirable. Systemic symptoms and signs warrant investigation for sepsis/septicemia.

Follow-up

A prolonged hospital stay is associated with chylous fistulas. Nutritional follow-up is important because many patients with chylous fistulas have been diagnosed with cancer and may need further treatment in the form of chemotherapy or radiotherapy.

Complications

Untreated, chylous fistulas may lead to metabolic, nutritional, and immunologic complications. The patient’s general health may deteriorate with weakness, dehydration, edema, and emaciation setting in. Electrolyte disturbances include hyponatremia, hypochloremia, hypoproteinemia, and lymphopenia. Chylothorax may follow with an untreated mortality of 50% due to inflammation, tissue maceration, pleural rupture, compression, mediastinal shift, and, ultimately, cardiopulmonary compromise.[24, 42]

Outcome and Prognosis

At the turn of the 20th century, the mortality rate caused by chylous fistula was unacceptably high at 12.5%. If further complicated by a chylothorax, the untreated mortality rate approached 45-50%. The mortality rate has been greatly reduced to the point that most cases of chylous fistulas are treated conservatively with continued drainage and dietary measures, and mortality resulting from chylous fistula would be regarded as unusual, occurring in 0.25% of patients in a 2008 case series of 395 neck dissections.[43]

Future and Controversies

Chylous fistulas are likely to remain a recognized complication of head and neck surgery for the foreseeable future. Detailed anatomic knowledge and meticulous technique should limit its prevalence. Focus on the recognition and careful management of this condition will limit the morbidity associated with it. Future research avenues include standardization of the operative algorithm and optimization of medical therapy.