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Four-Duct Ligation
A Simple and Effective Treatment for Chronic Aspiration From Sialorrhea
CPT Christopher Klem, MC, USA;
Lt Col Eric A. Mair, USAF, MC
Arch Otolaryngol Head Neck Surg. 1999;125:796-800.
ABSTRACT
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Objectives To determine the effectiveness of bilateral submandibular and parotid duct ligation on children with severe neuromuscular impairment and chronic aspiration of salivary secretions and to identify any predictable anatomical connections between the submandibular duct and sublingual glands.
Design Case series; retrospective anatomical study of adult cadaveric submandibular gland specimens.
Setting Academic tertiary referral medical center.
Patients Five children with severe neuromuscular impairment and recurrent aspiration pneumonitis.
Intervention The children underwent bilateral submandibular and parotid duct ligation. The oral cavities of 8 cadavers were dissected to identify anatomical connections between the submandibular duct and sublingual glands.
Main Outcome Measures Incidence of postoperative aspiration pneumonitis; gross anatomical connections between the submandibular duct and sublingual gland in cadaveric specimens.
Results No postoperative airway obstruction, infection, or xerostomia was noted, and technetium scanning confirmed control of salivary secretions from major salivary glands. Caregivers noted diminished salivary secretions and no aspiration pneumonia.
Conclusions This new, simple intraoral procedure controls aspiration pneumonitis with minimal surgical dissection and has less morbidity than procedures involving major salivary gland excision. Ranula formation, a common complication of submandibular duct transposition, is unlikely in this procedure because the sublingual ducts are not interrupted.
INTRODUCTION
DROOLING IS common among children with cerebral palsy, occurring in an estimated 10% of cases.1 Children with severe cerebral palsy may also suffer from recurrent life-threatening pneumonitis secondary to aspiration of salivary secretions. Conservative treatment measures, such as behavior modification to lessen drooling activity, feeding programs to improve oral motor function, and pharmacotherapy to decrease saliva production, are often ineffective in these severely affected children, and surgery frequently offers the best hope for successful management.
Current surgical options to treat chronic aspiration of saliva include laryngotracheal separation and tracheotomy. These are relatively aggressive procedures that allow for improved control of aspirated secretions, but are often not acceptable options to caregivers. Other surgeries that diminish oral secretions include transtympanic chorda tympani and tympanic nerve section, submandibular gland excision, sublingual gland excision, and parotid duct ligation or repositioning. These have all been performed with various rates of success and morbidity. Bilateral parotid duct ligation combined with bilateral submandibular gland excision has been shown to be as effective as either laryngotracheal separation or tracheotomy in the treatment of chronic aspiration, but with fewer complications.2 Removal of the submandibular glands, however, requires external incisions and is associated with substantial morbidity.3-5
The physiological rationale behind the success of salivary duct ligation is functional atrophy of the affected gland. Although this is a controversial subject, numerous studies have shown either histological or radiographic evidence of glandular atrophy as a desired result of duct ligation or as an unintentional consequence of duct manipulation from various surgical procedures.6-7 Simple intraoral ligation of the major secretory ducts of the submandibular and parotid glands should induce atrophy of the glands and significantly decrease the production of saliva, thereby reducing the potential for aspiration of salivary secretions.
PATIENTS AND METHODS
Five patients, 1 to 17 years of age (median, 4 years), underwent surgery at the Walter Reed Army Medical Center, Washington DC, between July 1, 1997, and January 31, 1998. There was a 4-year-old girl and 4 boys aged 1.2, 3, 6, and 17 years. All patients had severe cerebral palsy and recurrent pneumonitis secondary to aspirated salivary secretions (average, 2.5 cases per year; range, 1 to 4 cases per year). More conservative methods of sialorrhea control were attempted in all cases before surgery but were unsuccessful because of the severity of neuromuscular impairment.
The operation was performed with the patient under general anesthesia with nasotracheal intubation in 3 cases and via preexisting tracheotomy in 2 children. The oral cavity was exposed with the aid of a rubber bite block. Bilateral parotid duct ligation was performed as previously described (Figure 1, Figure 2, and Figure 3).8-9
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Figure 1. Preoperative view of the left parotid duct papilla.
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Figure 2. The distal right parotid duct is isolated.
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Figure 3. Postoperative view of the right distal parotid duct, cauterized and tied.
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For the second half of the operation, the distal submandibular duct papillae on either side of midline were identified, and 1 mL of 1% lidocaine with epinephrine 1:100,000 was injected around the site. A submucosal incision was then made between the papillae along the line of the sublingual frenulum with a No. 15 blade scalpel. A Kelly clamp was placed on the duct orifice to hold the duct while submucosal blunt dissection along the distal duct was performed. Care was taken not to disrupt any sublingual ducts that might be entering the submandibular duct. When no more than 1 cm of the submandibular duct was exposed, the duct was tied in 2 places with silk sutures and the caruncle tip was cauterized on low power (Figure 4, Figure 5, and Figure 6). The procedure was then repeated on the opposite side. The small initial incision between the duct orifices was either left open or closed with an interrupted absorbable suture.
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Figure 4. Preoperative view of the submandibular duct papillae seen lateral to the frenulum of the tongue.
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Figure 5. The distal submandibular duct is located.
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Figure 6. Postoperative view of bilateral submandibular duct ligation.
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A single dose of perioperative antibiotics (second-generation cephalosporin) was used in all cases; however, no patient received postoperative antibiotics or corticosteroids. Because of the children's multiple medical problems and concern for potential airway management issues, immediate postoperative recovery occurred in the pediatric intensive care unit.
To demonstrate the extreme anatomical variation of the sublingual ducts and, thereby, help explain the 10% rate of ranula formation encountered in submandibular duct transposition, 16 fresh cadaveric specimens were dissected. Specifically, a pattern in the connections between the sublingual and submandibular duct was sought.
RESULTS
Immediate mild postoperative swelling in both the submandibular and parotid areas subsided within 2 to 3 days in all children. There were no instances of aspiration pneumonitis, airway obstruction, fever, or wound infection in the immediate postoperative period, and all of the children were able to be transferred to the pediatric ward the day after surgery in preparation for discharge. The children did not require intravenous hydration postoperatively because they tolerated their gastrostomy tube feeds without difficulty. Although 3 of the children (through the caregivers) complained of mild discomfort, this was effectively managed with nonsteroidal analgesics and acetaminophen. In all cases a marked decrease in the amount of drooling was noted by the caregiver before the patient was discharged.
The period of follow-up ranged from 10 to 15 months (median, 13 months). All follow-up data are from primary interviews with the patients' caregivers and by physical examination. No patient experienced an episode of aspiration pneumonitis since surgery. Every patient reported a substantial decrease in the amount of drooling from the preoperative state; however, there were no complaints of dry mouth. There were no instances of ranula formation or swelling in the floor of the mouth.
Postoperative technetium 99m albumin aggregated (Mallinckrodt, St Louis, Mo) scan was performed on 2 patients. Results showed decreased uptake in the parotid and submandibular glands. The sublingual glands were unaffected.
The results of the cadaveric dissections of the submandibular and sublingual ducts are shown in Table 1. We found a significant and unpredictable variation between both individual specimens and opposite sides of the same cadaver. In every specimen except 1, the sublingual glands sent multiple sublingual ducts that connected with the submandibular duct (Figure 7). All of these connections were more than 1 cm deep to the submandibular duct papilla.
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Results of Cadaver Dissections
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Figure 7. Cadaveric dissection demonstrating multiple sublingual connections with the submandibular duct.
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COMMENT
The cause of drooling in cerebral palsy appears to be multifactorial and includes poor posturing of the head, inadequate lip closure, spastic and thrashing tongue movements, and a defect in the oral phase of swallowing, all of which prevent saliva from effectively passing posteriorly to the oropharynx.10 Treatment options, including behavioral modification, oral stimulation, pharmacotherapy, and surgery, are all used, with varying degrees of effectiveness.
Children who aspirate their salivary secretions also have a dyscoordinate swallowing mechanism affecting primarily the pharyngeal phase of swallowing. Conservative measures, the success of which correlates directly with the degree of neuromuscular dysfunction, are often less effective in these severely impaired children, and surgery offers the most definitive treatment.
Many of the accepted surgical alternatives for treatment of sialorrhea focus on bypassing the dysfunctional oral phase of swallowing, while preserving salivary production. The beneficial aspects of saliva in bolus forming, dental health, and immunity are well established, so it is desirable to maintain some salivary flow.11 Surgical redirection of saliva to the oropharynx is commonly performed as bilateral submandibular duct transposition, although the sublingual glands are frequently sacrificed to minimize postoperative ranula formation. Transposition of Wharton ducts with or without excision of the sublingual glands controls sialorrhea and is regarded as physiologically superior to surgery that solely decreases salivary output. This procedure, however, is contraindicated when there is a history of aspiration pneumonitis.12-14
The submandibular glands produce up to 70% of resting saliva, so it is necessary to alter this flow to achieve adequate results.15 Bilateral submandibular gland excision combined with parotid duct ligation has effectively decreased aspiration of saliva in neuromuscularly impaired patients.2
Removal of the submandibular glands is a relatively common procedure; however, it is associated with substantial morbidity. Permanent facial palsy caused by damage to the marginal mandibular nerve occurs in up to 7% of patients, while temporary marginal mandibular nerve paresis is reported in 36% of cases.4 Although not as common as damage to the facial nerve, lingual and hypoglossal nerve damage are also reported.3-4,16 Further, the presence of an external incision, subsequent scarring, the additional potential for wound infection, and prolonged general anesthesia make submandibular gland excision particularly unattractive to the parents or caregivers of children who have frequently undergone many surgical procedures.
Parotid duct ligation is commonly performed to aid in the control of sialorrhea, but the effectiveness of the procedure is controversial.9, 13, 17 In contrast, submandibular duct ligation has not been routinely performed. Several comments in the literature raise concerns of the increased likelihood of calculus formation compared with ligation of the parotid gland, because of the higher alkalinity and viscosity of submandibular saliva, the higher concentration of calcium and phosphate salts, the longer duct system, and stasis associated with the orifice being uphill from the gland.9, 18 By this rationale, ligation of the submandibular ducts should exacerbate calculus formation. However, there is no reference in the literature to submandibular calculus formation after duct transposition, despite radiographic evidence of functional gland atrophy in nearly 50% of transposed ducts.6-7 This suggests that one significant, yet unintentional, result of routine submandibular duct transposition may actually be a functional ligation of the duct with subsequent gland atrophy and no stone formation.
In a study of unilateral submandibular duct ligation in rats, the histological effects of acute duct ligation were noted to be atrophy of the acinar cells with reversion to a resting or inactive state and consequent loss of specialized function.19 Experimental evidence of atrophic changes indicates that simple intraoral ligation of the submandibular ducts should achieve results similar to those of submandibular gland excision without the potential complication of nerve paresis or the morbidity associated with external incisions. The isolated case in the literature of purposeful ligation of the submandibular ducts reported good control of sialorrhea, progressive involution of the submandibular glands, and no xerostomia or other complications.20
Because the intraoral incision and distal dissection are similar to those used for submandibular duct transposition, one might speculate that ranula formation would also be a complication associated with submandibular duct ligation. These mucous retention pseudocysts arise when the sublingual ducts or glands are traumatized and not excised, an almost inevitable consequence of the extensive dissection required to posteriorly relocate the submandibular duct.
There has been no evidence of ranula formation in any of the 5 children described in this report. Although this is a small series, we predict that ranulas will not be a common complication of submandibular duct ligation, since less than 1 cm of the duct must be dissected for adequate ligation, significantly decreasing the likelihood of sublingual duct trauma.
Anatomically, the submandibular duct lies medial to the sublingual gland as it travels anteriorly toward the sublingual furuncle just lateral to the lingual frenulum. Each almond-shaped sublingual gland sends between 5 and 15 minor sublingual ducts either to open into the floor of the mouth along the sublingual fold or to connect with the submandibular duct.21 As demonstrated in the cadaver dissections, the pattern of connections between the sublingual and submandibular ducts is unpredictable. In none of the 8 cadavers, however, were any sublingual ducts found within 1 cm of the submandibular duct papilla.
Xerostomia, a potential complication of any surgery that affects salivary flow, has not been reported by any of the 5 patients in this series. After ligation of the 4 major salivary ducts, the only saliva present in the oral cavity should be that which comes from the sublingual and other minor intraoral salivary glands. This appears adequate to moisten the oral mucosa and permit swallowing. Other studies, in which bilateral parotid duct ligation and bilateral submandibular gland excision were performed, also described few problems with xerostomia postoperatively.2
A major increase in dental caries is associated with surgical alteration of salivary flow. None of the 5 patients in this study reported an increase in caries; however, the follow-up is short, and this possibility should be followed up over time. Among the different surgical procedures performed for control of sialorrhea, no significant differences in caries prevalence have been identified. Since caries prevalence is related to the severity of cerebral palsy, intensive preoperative and postoperative preventive dental therapy should be performed in the severely impaired children who undergo this procedure.11, 22
CONCLUSIONS
Aspiration of salivary secretions can be a life-threatening problem in children with neuromuscular impairment. Simple intraoral ligation of the 4 major salivary ducts is effective in diminishing oral secretions and reduces the incidence of aspiration with fewer complications and less morbidity than other surgical procedures. We now successfully use this procedure not only in children with recurrent aspiration pneumonitis, but also as a surgical alternative for chronic drooling without aspiration.
AUTHOR INFORMATION
Accepted for publication October 1, 1998.
The opinions or assertions contained herein are the private views of the authors and are not to be construed as official or as reflecting the views of the Department of the Army or the Department of Defense.
Presented at the 13th Annual Meeting of the American Society of Pediatric Otolaryngology, Palm Beach, Fla, May 13, 1998.
Corresponding author: Lt Col Eric A. Mair, USAF, MC, Department of Otolaryngology–Head and Neck Surgery, Walter Reed Army Medical Center, Washington, DC 20307-5001 (e-mail: ericmair{at}aol.com).
From the Department of Otolaryngology–Head and Neck Surgery, Walter Reed Army Medical Center, Washington, DC.
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