Complications of Surgery of the Salivary Glands and Sialoendoscopy
Surgery of the major salivary glands (parotid gland, submandibular gland, and sublingual gland) is often challenging despite the standardization of surgical procedures in recent years and the aids now available to surgeons. Avoiding complications requires more than surgical skill and adequate surgical instruments: the surgeon must also be familiar with the complex anatomy of the facialis nerve and other adjacent vascular and neural structures. The more tissue structures and anatomy have been altered by inflammation, tumors, previous surgeries and radiation treatments, the more important these aspects become. Potential complications and their treatment as well as measures to prevent and avoid complications during surgery of the major salivary glands are the subject of the present chapter.
In addition to an exhaustive anamnesis of the nature and duration of individual symptoms, a complete clinical examination of the patient by an Ear, Nose and Throat specialist is an absolute necessity. It is important to palpate the gland and neck to obtain a characterization of the localization, dimension, mobility, and pressure sensitivity of any masses. The main purpose of gland massage is to facilitate the evaluation of the saliva secreted through the ostia. Preoperative clinical assessment of facialis nerve function is made according to the criteria formulated by House and Brackmann.1
The method of choice for imaging the anatomy and pathology of the major salivary glands in both the preoperative and postoperative periods is ultrasonography. It is noninvasive, economical, and involves no exposure to radiation or contrast agents. With this method, the localization and number of stones are just as easy to determine as those of tumors and other pathologic changes.2 For some time, sialoendoscopy of the Stenson and Wharton ducts has, in the case of unclear swellings, closed a diagnostic gap in the differentiation of stones, duct strictures, and inflammatory changes in the deferent ducts.3,4
What, in our view, would be supplemental imaging with magnetic resonance imaging or computed tomography is used, for example, for tumors in the deep lobe of the parotid gland or infiltrative tumor growth into adjacent tissues (bone, base of skull). Positron emission tomography is indicated when searching for distant metastases of undifferentiated carcinomas or in the detection of recurrence.5
Ultrasonography is the method of choice for preoperative and postoperative evaluation of anatomy and pathology of the major salivary gland.
Fine Needle Aspiration Cytology, Core Needle Biopsy, and Intraoperative Frozen Sections
The assessment of the significance of fine-needle aspiration cytology (FNAC) in the diagnosis of salivary gland lesions is varied. Factors favoring FNAC include the virtual absence of complications (hemorrhaging, infections) and easier planning of surgical procedures. Bleeding can usually be staunched by simple compression. Antibiotics effective against staphylococci and streptococci are indicated if infections occur. However, good results are obtained with FNAC alone when the procedure is performed by the pathologist.
On the other hand, there is a criticism that FNAC allows insufficient differentiation of tumor types, and therefore has little influence on therapeutic planning. The sensitivity and specificity of the method have been assessed by various studies to be between 55 and 98%.6 Ultimately, surgery is indicated in the majority of patients even with negative FNAC. In the case of a suspected malignancy, intraoperative frozen section diagnostics should also be used for further clarification, even if this method may deviate considerably from the reference standard of histology.7 For example, if a decision concerning resection of the facialis nerve is involved and the frozen section diagnosis is unclear, then waiting for definitive histology and a two-session procedure is indicated.
FNAC is indicated in patients with high levels of surgical and anesthesiologic risk or who reject surgery for other reasons, to rule out a malignancy.
A core-needle biopsy represents an exceptional measure that is appropriate in certain situations and should be avoided with salivary gland tumors because of the risk of tumor cell spillage.
Facialis Monitoring and Facialis Stimulation
Intraoperative neuromonitoring of the facialis nerve makes it easier to identify the nerve and facilitates continuous monitoring of neural function.8,9 Whereas intraoperative monitoring of the facialis nerve is considered useful in difficult cases, such as revision surgeries, the necessity of neuromonitoring in routine parotid surgery is still controversial.10,11
Arguments frequently heard against the routine use of neuromonitoring include, besides the additional time required, a false sense of security leading to hasty and less careful work. Most studies have not, however, described any false-negative responses.9 However, there could be legal consequences if monitoring is not performed.10 In our experience, the small amount of additional time required can be compensated for by briefer surgery times.9 Nerve monitoring, when properly performed, does not cause complications, so there would seem to be no solid arguments against its use, although it cannot of course replace the anatomical knowledge and experience of the surgeon.
Monitoring of the facialis nerve in extracapsular dissections is a conditio sine qua non (see below).
Use of Microscope or Loupes
Depending on the intraoperative situation, preparation of the facialis nerve and its branches can be performed either with the naked eye or with the help of optical aids such as loupes or a microscope. Dogmatic statements on this would be out of place here. Such aids are normally useful and indicated for revision procedures and reconstructive surgery.
Surgery of the Parotid and Submandibular Glands
In the majority of cases, benign and malignant glandular tumors represent indications for open surgical procedures on the parotid or submandibular glands. Justifications for surgical procedures may also include unclarified systemic diseases (e.g., Sjögren syndrome or sarcoidosis), or inflammatory changes such as sialolithiasis or chronic recurrent sialadenitis.
The following parotid gland procedures can be differentiated according to their level of invasiveness.
Biopsies can be taken with a relatively low level of risk, for example, from the pretragal region of the parotid tissue. Indications for this would normally be the clarification of inflammatory salivary gland diseases or suspected lymphoma. Inadequate specimen biopsies from tumors such as pleomorphic adenoma should be avoided because of the risk of tumor cell spillage ( Fig. 22.1 ).
In the historical sense, enucleation is the surgical opening of the tumor capsule followed by intracapsular tumor reduction. The technique is used today, for example, in neurosurgical intervention on brain tumors. It can be considered obsolete for parotid tumors.
This technique describes the extirpation of a tumor from outside the capsule in healthy tissue, ideally together with a surrounding layer of healthy parotid tissue. Extracapsular dissection is often incorrectly called enucleation, an error that must be avoided. In contrast to partial parotidectomy, the main trunk of the facialis nerve is not exposed.12
Following exposure of the main trunk of the facialis nerve, only part of the parotid gland is removed along with the tumor and surrounding glandular tissue. Most of the gland remains in situ.
Lateral or Superficial Parotidectomy
Following exposure of the main trunk of the facialis nerve and its peripheral branches, the entire lateral segment of the gland is removed.
This term refers to the complete removal of the gland with exposure of the facial nerve and its branches. The synonymous term “near total parotidectomy”, which frequently corresponds to the intraoperative finding, reflects the fact that some glandular lobes are usually left in situ.
In the case of malignancies that infiltrate the facialis nerve over a wide area, this term refers to resection of parts or the entirety of the facial nerve, usually accompanied by reconstructive measures. In addition to direct neural suture, nerve grafts and other techniques of static or dynamic rehabilitation of the paralyzed face are used.13,14 Dynamic rehabilitation is performed, for instance, with the help of the temporal or masseter muscles.15 Static rehabilitation is done by harnessing, in which the fascia lata and contemporaneous tarsorraphy or tarsal tongue plasty is used and a gold or platinum weight is implanted in the upper lid.16
The submandibular gland is usually extirpated through a horizontal skin incision parallel to the mandibula. The glandular parenchyma (including the uncinatus process) is completely removed along with parts of the main deferent duct. Partial resections are not performed because of the risk of salivary fistula.
Normal Postoperative Course
There is normally no pronounced swelling or pain in the wound area. If this should occur, then the possibility of a complication must be considered and investigated accordingly.
Bandage changes and wound control procedures, as well as clinical functional tests of the facialis nerve, should be performed at regular intervals.
At the end of the intervention, subtle hemostasis and insertion of a drainage tube help to prevent the development of postoperative hematomas and seromas. Views differ on the use of Redon drains in parotid surgery. Due to possible direct contact with the facialis nerve, we prefer a rubber drain to a Redon drain in parotid gland procedures. In extirpations of the submandibular gland, we also use a standard size Redon (10 Fr) drain under suction until the 2nd postoperative day. Removal of the drain depends on how much material is still being drained off in each individual case (< 20 mL/day).
The volume of postoperative wound secretion correlates with the histology of the tumor (malignant > benign) and is independent of the age and sex of the patient, intraoperative blood loss and the presence of hypertension.17 A drain is not required in minor procedures such as a specimen biopsy or circumscribed extracapsular dissection.
Wound bandaging types and techniques are often the subject of discussions on how to achieve normal wound healing. Clinical practice undoubtedly favors the use of tight compression bandages to prevent the development of hematomas, seromas, sialoceles, and salivary fistulas, especially if no drains have been used or the wound areas are large ( Fig. 22.2a, b ). Jianjun et al18 emphasize the importance of compression bandages in their publication, in which they proposed a special setup (similar to headphones) for the reduction of postoperative fistulas and wound healing disturbances: such a setup was employed with a high level of success in a controlled study.
There are, however, exceptional cases in which the administration of perioperative antibiotic prophylaxis is expedient (known cardiac defect, immunosuppression, inflammatory changes in the salivary gland, procedure lasting > 4 hours), but it should not be practiced routinely.19
The removal of dermal sutures can be performed safely from the 7th postsurgical day onward.
Typical Postoperative Complications
Typical complications of salivary gland surgery include defective wound healing, wound infections including otitis externa, dehiscences and hypertrophic scars, seromas, hematomas, sialoceles, salivary fistulas, anesthesias and paresthesias around the dermal incision or the area supplied by the great auricular nerve, temporary and permanent facialis pareses and, in the later course, Frey syndrome or gustatory sweating.20
Hematomas and Impaired Wound Healing
Immediate postoperative impaired wound healing is frequently associated with the development of hematomas, seromas, and sialoceles, and for this reason these phenomena are discussed together here. In addition to specific patient characteristics (status of blood coagulation, vascular status, immune status), factors contributing to the occurrence of these problems also include the wound surface size and the extent of the procedure. Subtle hemostasis with bipolar coagulation and the interruption of flow in larger veins (retromandibular vein) or arteries (maxillary artery) can contribute to the prevention of major postoperative hemorrhaging. The frequency of postoperative hematomas is around 3 to 7%. The most frequent causes are insufficient intraoperative hemostasis and sudden increases in venous or arterial blood pressure.21,22
Coagulation inhibitors (phenprocoumon, clopidogrel, acetylsalicylic acid) should be discontinued at least 1 week before the procedure. If anticoagulation cannot be discontinued, a switch to low-molecular-weight heparin or full heparinization is recommended.
The first sign of a complication is usually painful swelling around the wound. If such a swelling develops rapidly after a total parotidectomy, acute postoperative hemorrhage with hematoma is the first possibility that comes to mind. This is usually characterized by a livid skin color, but sometimes by swelling alone ( Fig. 22.3a, b )
Depending on the extent of hemorrhaging or the hematoma, emergency measures are required because of the loss of blood or secondary swelling of the soft tissues of the neck: the cutaneous and subcutaneous sutures must be opened wide and the hematoma must be removed either by suction or digitally, while at the same time sparing the facialis nerve. In case of severe bleeding in the deep soft tissues of the neck, the respiratory passages must be protected. If the hemorrhaging does not cease under compression, surgical revision is indicated ( Fig. 22.4 ). Otherwise, flushing of the wound area, placement of a rubber drainage tube, and application of a compression bandage will suffice.
If the swelling does not develop until days 3 to 5 after surgery, following removal of the drain, and if the salivary gland parenchyma has been retained, sialoceles, or even seromas, have probably formed and saliva is being retained in the wound. In cases of extensive findings with pronounced pain, reopening of the wound and removal of the secretion with the insertion of another wound drain is recommended. In the case of hematomas, seromas, or sialoceles, the administration of an antibiotic is warranted to avoid the development of secondary infections. Flushing with antiseptic solutions and physiologic saline solutions is then indicated. In less severe cases, sonography can be used to assess their dimensions, after which a decision can be made on whether to puncture and use a compression bandage or whether to puncture only. Whichever is chosen, these patients require further monitoring until the findings have resolved.
If pronounced reddening has developed in the postoperative course as a sign of a phlegmon, an antibiotic is indicated. Abscesses must be punctured or split. The normal cutaneous germs as well as Staphylococcus aureus should be taken into account as the most frequent causes of postoperative wound infections. The antibiotics that would be indicated in these cases are amoxicillin with a β-lactamase inhibitor, a second-generation cephalosporin or, in the case of a penicillin allergy, clindamycin. In individual cases, antibiosis should be performed in keeping with the results of a smear test. In addition to antibiotic treatment, we also consider opening and drainage to be necessary in the case of abscesses.
Necrosis of the skin flap is a rare postparotidectomy complication.21 The necrosis usually develops inframastoidally at the caudal end of the flap ( Fig. 22.5 ). In particular, if extensive cutaneous flaps are prepared for cosmetic improvement, as in a facelift, the risk of necrosis is increased. In addition to cautious intraoperative handling of the skin flap (drying, pressure), the main causal factors of such a complication may primarily include nicotine abuse, diabetes mellitus, or previous radiotherapy.23,24 Therapy comprises the removal of the necroses and secondary wound closure after healing.
Sialoceles, Seromas, and Salivary Fistulas
Sialoceles may occur following surgery of the salivary glands and are also observed as a consequence of penetrative injuries of the salivary gland ( Fig. 22.6a, b ). A sialocele is defined as an accumulation of saliva, either in a deferent duct (also called a retention cyst) or after trauma or other injury to the glandular parenchyma, in such cases often defined by an inflammatory reaction, such as in a pseudocyst. The incidence is described as 5 to 10% following partial or lateral parotidectomy.22,25 A seroma shows a similar clinical picture, but is characterized by a lower concentration of amylase. This is of no practical consequence, however.
The therapeutic options described in the literature are in most cases anecdotal.26 The descriptions include repeated punctures with aspiration and the application of suitable compression bandages. Restitutio ad integrum follows in most cases after 4 to 6 weeks. If the sialocele is allowed to drain to the outside by opening the wound area, a salivary fistula may form, which usually closes within 6 weeks at the latest.27 Antibiotic treatment that also considers the possibility that a staphylococcus could be the pathogen can be administered, if the tissue shows corresponding inflammatory changes.
In the rare cases of persistent sialoceles, oral anticholinergics (ipatropium bromide) or dermal anticholinergic applications (transdermal scopolamine) can be used.
The relevant contraindications and potential systemic adverse effects are to be taken into account below. Nowadays, a neurectomy of the chorda tympani is certainly contraindicated. Successful treatments with botulinum toxin have also been described recently.28 A study by Witt26 confirmed that sialoceles occur with significantly greater frequency following partial resections of the parotid gland than after total parotidectomy. Regardless of whether the sialocele was punctured, healing without further complications was observed in all cases within 4 weeks. The author concluded that it is permissible to wait at least 4 weeks following surgery to carry out ultrasonographic evaluation before considering any further therapeutic alternatives.
Considering the development of postoperative wound healing defects, including salivary fistulae, our investigation (n = 452), which covers all parotid gland surgeries, revealed an incidence level of 9% ( Fig. 22.7 ). The lowest level of occurrence was after partial parotidectomy. Salivary flow ceased an average of 2.3 weeks after total parotidectomy, 4.6 weeks after lateral parotidectomy and 4 weeks after partial parotidectomy. All fistulae had healed within 11 weeks.12,20 Jianjun et al described covering the defect with a flap taken locally from the parotid fascia, which significantly reduces the frequency of salivary fistula.29 Application of a compression bandage is a further measure that reportedly reduces the frequency of occurrence.18 Similar to that of sialoceles, therapy of salivary fistulas involves the administration of anticholinergic agents (see p. 235). According to our own experience and the literature, local injection of tetracyclines can accelerate the healing process.30–32 The local inflammatory reaction results in a closure of the fistula. Botulinum toxin can also be used successfully to inhibit salivary gland secretions.33 If the fistula persists, the application of botulinum toxin can be supplemented by a circumscribed surgical revision with freshening of the wound margins and, if necessary, the insertion of a TachoSil patch (Takeda Pharmaceuticals, Zurich, Switzerland) (a sponge containing the active substances human fibrinogen and thrombin as well as horse albumin and collagen).
Before considering major surgical revision with removal of the residual salivary gland and the attendant risk of injury to the facialis nerve, it is now possible to consider local irradiation of the residual salivary gland tissue with up to 30 Gy34 ( Fig. 22.8a–d ). The last resort would then be surgical removal of the residual gland.