Учебники / Textbook and Color Atlas of Salivary Gland Pathology - DIAGNOSIS AND MANAGEMENT Carlson 2008

with diminishing diameter (Figure 12.10). This variability in number of fasicles and structure along the extratemporal facial nerve constitutes a difficulty in facial nerve repair (Captier, Canovas, Bonnel, Seignarbieux 2005). The use of tubes (e.g., collagen) to support the anastomosis and prevent connective tissue in-growth and also tissue glues (e.g., fibrin) to replace sutures and their foreign body reactions have been advocated. However, the tubes can themselves cause foreign body reactions and possible compression. Regarding the tissue glues, animal experiments appear to show sutures to be superior. In the rabbit model axonal growth was faster and greater with epineural suture than fibrin adhesive (Junior, ValmasedaCastellon, and Gay-Escoda 2004). Although the rate and amount of reduction in conduction velocity was equivalent between the two methods, the authors concluded that epineural suture appears to

be the method of choice. In another study in the rat model looking at suture and the effects of platelet rich plasma (PRP) and fibrin sealant, the best return of function for the facial nerve was again with suture (Farrag, Lehar, and Verhaegen et al. 2007). The authors did note a favorable neurotrophic effect for the PRP but no benefit for the fibrin sealant. As it is vital that the anastomosis be tension free, difficulty is encountered when a gap between the nerve ends exists. In a cadaver study, Gardetto, Kovacs, and Piegger et al. (2002) showed that removal of the superficial part of the parotid gland could allow overlap of the cut branches of the facial nerve. They found it possible to bridge gaps of 15 mm in the temporo-zygomatic branches, 23 mm in the buccal-mandibular branches, and 17 mm in the nerve trunk. Following this experimental work the authors have reported successful clinical results on 3 patients, recommending the

Figure 12.9a. Penetrating wound through ear and parotid gland.

Figure 12.9b. Exploration of wound reveals transection of the superior branch of the facial nerve. (Ruler from surgical marker makes a good background for microsuture if custom microsurgical background material is unavailable.)

Figure 12.9c. Post-microsurgical repair.

Figure 12.9d. Post-suturing of wounds. This case treated by Dr. J. Caccamese, Dept. OMS, University of Maryland.

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technique for gaps up to 15 mm but cautioning against its use in the presence of infection or nerve defects (Piza-Katzer et al. 2004). In another approach the use of a rapid nerve expander (2 cm/30 minutes) was used to bridge gaps up to 3 cm (Ya, Gao, and Wang 2007). In 9 patients 5 achieved good results with EMG peak value of mimetic muscles 82–95% of the normal side, 3 cases were fair with EMG 60–90%, and 1 case poor with EMG 55%. Other surgical options in this situation are the use of a tube as a conduit and grafting. In 7 patients with post-traumatic defects up to 3 cm the use of a bioabsorbable polyglycolic acid tube was reported as giving very good results in 1 case, good in 4, and fair in 2 (Navissano et al. 2005). The two commonest sites for donor nerves for the facial nerve are the greater auricular, which is adjacent to the surgical field, and the sural nerve. Surgical principles for repair follow those for direct anastomosis. As expected, facial nerve function from cable nerve graft interposition is not as good as end to end anastomosis (Malik, Kelly, and Ahmed et al. 2005). If there is widespread destruction of multiple branches from an injury such as a gunshot the entire superficial cervical plexus can be used to supply multiple grafts.

Frey’s Syndrome

Although Frey’s syndrome is now most commonly seen in relation to parotid surgery, it was originally described after a shotgun injury to the parotid gland (Frey 1923); however, despite Frey’s landmark paper, gustatory sweating was probably first described by Baillarger in 1853 (Dulguerov, Marchal, and Gusin 1999). In the trauma situation obviously the problem is management and treatment of the condition, whereas in the postparotidectomy cases much work has been done on prevention.

Previously reported treatments of Frey’s syndrome have included topical and systemic anticholinergics, tympanic neurectomy, sectioning of the auriculotemporal or glossopharyngeal nerves, or interposition of fascia lata between the parotid bed and overlying skin. Currently the use of botulinum toxin is the most frequently reported therapeutic modality for Frey’s syndrome. A report of 33 patients with Frey’s syndrome treated by intracutaneous injection of 16–80 IU of botulinum toxin A showed all symptoms to resolve within a week (Eckardt and Kuettner 2003). In a prospective

Figure 12.10a. Extensive penetrating wound anterior to the parotid gland, which involves the peripheral branches of the facial nerve.

Figure 12.10b. Nerve branches identified for microneural repair.

Figure 12.10c. High-power view of completed repair.

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nonrandomized, nonblinded study of 11 patients treated with botulinum toxin A with follow-up 6– 23 months, only 1 patient recurred and was successfully retreated (Kyrmizakis, Pangalos, and Papadakis et al. 2004). A prospective randomized trial to establish the ideal dosage and length of effect of botulinum toxin A was carried out on 20 patients divided into two groups receiving either 2 MU/cm2 or 3 MU/cm2. In the 3 MU/cm2 group a single injection resulted in nearly complete absence of gustatory sweating during the 12 month followup period. In the 2 MU/cm2 group 44% of the total skin areas were still sweating and required a second injection, and the authors concluded that 3 MU/cm2 is the recommended dose (Nolte, Gollmitzer, and Loeffelbein et al. 2004). Some authors have cautioned that the effect of botulinum toxin

Figure 12.11a. Lateral facial view of patient complaining of gustatory sweating (Frey’s syndrome).

in Frey’s syndrome is often temporary and further injections may be necessary depending upon the initial dose and the length of time followed (Ferraro et al. 2005).

In regards to parotidectomy patients, probably 100% will have gustatory sweating if tested with starch and iodine (Laage-Hellman 1957) (Figure 12.11). However, few patients clinically notice this problem and most do not wish for treatment, so that this condition will be underestimated in clinical reports. Frey’s syndrome is rarely reported after submandibular gland removal. Berini-Aytes and Gay-Escoda (1992) reviewed 206 submandibular gland excisions and found only 1 case of Frey’s syndrome, while Teague, Akhtar, and Phillips (1998) reviewed the literature and could find 7 reported cases since 1934.

Figure 12.11b. Bottle of iodine solution that is painted on the patient’s face and then covered in corn starch.

Figure 12.11c. While the patient eats an apple the cornstarch is discolored blue-black, indicative of gustatory sweating.

The techniques described for prevention of Frey’s syndrome depend upon placing a barrier between the parotid bed and skin to prevent the growth of the secretory parasympathetic nerves from the parotid into the sweat glands, causing a paradoxical innervation. Acellular dermis has been used with success but with a higher complication rate (Govindaraj, Cohen, and Genden et al. 2001). Temporoparietal flaps and the superficial musculoaponeurotic system (SMAS) have been used with good outcomes in 146 parotidectomy patients (Cesteleyn et al. 2002). In reviewing 160 patients followed from 5 to 22 years treated with an interpositional SMAS layer at the time of parotidectomy and tested with starch/iodine during follow-up, no cases of Frey’s were encountered (Bonanno et al. 2000). Other reported barriers have been the use

of parotid gland fascia (Zumeng, Zhi, Gang et al. 2006) and sternocleidomastoid muscle flaps, with mixed results (Filho et al. 2004; Kerawala, McAloney, and Stassen 2002).

It would appear that Frey’s syndrome is preventable in most cases, and perhaps the use of the SMAS layer is the most convenient for the surgeon.

Hollowing

This is a complication seen in patients following parotidectomy rather than trauma and can be managed in a variety of ways. Reconstruction at the time of surgery to prevent the defect occurring is preferable to secondary reconstruction, when scarring and the superficial position of the facial nerve post-parotidectomy increase the risk of nerve damage. Various techniques have been used, some of which have been discussed in this chapter in relation to Frey’s syndrome and in chapter 8. Techniques include the use of layered acellular dermis, free fat grafts (Figure 8.4), use of the SMAS layer, temporalis, and sternocleidomastoid flaps, as well as microvascular free flaps including fascial forearm flaps for larger defects. Choice of technique will depend on the size of the defect, the surgeon’s own experience, and the wishes of the patient.

TRAUMA TO SALIVARY GLAND DUCTS

Transection

As has already been discussed above in the sections on fistulae and sialoceles related to parenchymal trauma, conservative management is usually satisfactory except in those cases where the injury involves partial or complete transection of the duct. Under these circumstances most papers have indicated that resolution is less certain and takes longer, with active management frequently required. There are studies that support conservative measures in duct injuries and in one report, of 19 patients with duct injury confirmed by methylene blue dye injection who were treated nonoperatively, 9 patients (47%) healed without complications. Although 7 patients (36.8%) developed salivary fistulae and 4 (21%) sialoceles, these were described as short-term and resolved without the need for surgery (Lewis and Knottenbelt 1991). However, in most cases current management is

302 Trauma and Injuries to the Salivary Glands

Figure 12.12. Surface markings of the parotid duct are shown by a line drawn from the tragus of the ear to bisect a line drawn from the alar base to the commissure. The middle third of this line (arrow) is surface marking of the parotid duct.

directed toward primary repair and the clinician must therefore have a high level of suspicion for injuries involving the region of the parotid duct. The anatomic surface markings of the duct are illustrated in Figure 12.12. Confirmatory evidence for transaction is obtained by cannulating the distal portion of the duct through Stenson’s papilla and observing the catheter in the wound (Figure 12.13), or by injecting saline or a small (1 cc) amount of methylene blue through Stenson’s papilla. Identification of the proximal end may be difficult, as it can retract into the gland substance. Milking the gland to obtain salivary flow is helpful in these circumstances, and the anesthesiologist must be cautioned preoperatively against the use of antiparasympathetic agents. If the proximal and distal ends of the duct are identified and can be coapted, then microsurgical repair can be carried out (Hallock 1992) (Figure 12.14).

The use of stents (usually indwelling catheters) for 10–14 days to prevent stenosis is advocated by some and appears a reasonable hypothesis, although no long-term studies of these injuries

with and without stenting have been published. A technique of using a 4 F Foley embolectomy catheter for identification of the transection and then leaving it in place as a stent has been described (Etoz, Tuncel, and Ozcan 2006). When the proximal and distal ends of the duct cannot be coapted due to tissue loss, repair using a vein graft has been reported (Heymans et al. 1999). Steinberg and Herréra (2005) recommended the use of sialography postoperatively to assess the result of duct repair, stating that this technique may not always be practical or possible in the acute setting. However, we have used sialography intraoperatively (Figure 12.13).

When the injury is too proximal, the wound is avulsive, or the duct cannot be identified, then the clinician can either create an intraoral fistula or ligate the proximal duct. A controlled fistula can be created by suturing the proximal duct through the buccinator into the oral cavity if enough length is present, or by placing a catheter or drain from the area of the wound into the mouth and leaving it to fistulize (Figure 12.15). Although tying off the proximal duct to cause eventual atrophy has been proposed (Van Sickels 1981), in our experience this is unpredictable and even with the use of pressure and antisialogogues these patients can have considerable swelling and pain. Chemical denervation using botulinum toxin A may help to achieve a good outcome in these circumstances (Arnaud et al. 2006).

In the case of the submandibular duct, transection is usually iatrogenic as a result of surgery on the sublingual gland, sialolithotomy from Wharton’s duct, or resection of floor of the mouth cancer. In this case sialodochoplasty with repositioning of the duct posteriorly is all that is required. One of the authors formerly used a catheter as a stent (Ord and Lee 1996) following reposition of Wharton’s duct in floor of the mouth cancer; however, now the duct lumen is identified and one blade of a sharp iris scissors is inserted and a vertical cut through one wall of the duct carried out. The duct is now “fish-tailed” and sutured to a newly created hole in the oral mucosa with 6-0 nylon sutures. Stenosis and stricture have not been a problem with this technique.

Figure 12.13a. Patient with cheek laceration that was primarily sutured and that now has developed sialocele due to missed duct injury.

Figure 12.13b. Wound reopened for re-exploration; the duct is discovered to be transected. Vessel loop around distal end of duct. Lacrimal probe passed from intraoral through Stenson’s duct into the wound (short arrow).

Figure 12.13c. Stenson’s duct is approximated after finding the proximal end of the duct by milking the gland. The duct is cannulated and contrast dye injected for intraoperative sialogram.

Figure 12.13d. Fluoroscopic image of intraoperative sialogram with repaired duct (arrow). Case treated by Dr. D. Coletti, Dept. OMS, University of Maryland.

Figure 12.15a. Gunshot wound entering at right parotid region with exit at left infraorbital region as indicated by suction tubing.

Figure 12.15b. The parotid duct is identified and dissected from the wound to be cannulated as shown.

Figure 12.15c. The duct is diverted intraorally via the cannula. Note powder burn at entrance wound.

Figure 12.15d. Final repair. This case treated by Dr. J. Caccamese, Dept. OMS, University of Maryland.

Stenosis of the Duct

When ductal injuries are not surgically repaired immediately, complications such as fistulae and sialoceles may arise and their management has been discussed. If the duct has not been surgically repaired by 72 hours, conservative or medical therapy is recommended (Arnaud et al. 2006). In the long term, stricture of the duct may occur (Figure 12.16), although most strictures are sec-

ondary to inflammatory or infective conditions. In cases of intraductal salivary gland obstruction, 22.6% of 642 cases were due to strictures, which were more common in females (Ngu, Brown, and Whaites et al. 2007). When this occurs at the distal end of Stenson’s duct, excision and diversion of the duct into the oral cavity may be feasible. When the main duct is involved with strictures, sialoendoscopy may be useful to dilate the strictures using