Salivary Gland Fistula

Definition

Classification

Etiology

• Parotidectomy (most common source of case-series data)
• Submandibular gland surgery
• Post-Sistrunk procedure (thyroglossal duct cyst excision) - salivary fistula can develop from minor salivary glands near the tongue base musculature
• Total laryngectomy - pharyngocutaneous fistula (salivary leak from pharyngeal closure)
• Penetrating facial trauma: parotid duct injuries are often missed and manifest later as a fistula
• Accidental lacerations, blast injuries, vehicular accidents

• Salivary gland abscess pointing and draining to skin

Pathophysiology

Clinical Features

• Skin opening with clear or slightly turbid fluid discharge (saliva)
• Discharge increases after meals (gustatory stimulation)
• Associated local inflammation, swelling, or scarring
• May be preceded by a sialocele (fluctuant subcutaneous swelling)
• In pharyngocutaneous fistula after laryngectomy: increased turbid drain output, erythema, edema around wound closure, draining purulent material and saliva (occurring 1-6 weeks post-operatively)
• Possible associated facial nerve palsy or sialocele depending on the extent of injury

Diagnosis

• History of trauma or surgery to the parotid/submandibular region
• Characteristic meal-related increase in discharge
• Amylase estimation of the discharge fluid (elevated amylase confirms salivary source)
• Aspiration of fluid - sent for amylase levels

• Methylene blue injection - dilute methylene blue injected transorally into the parotid duct; blue exudate from the fistula tract confirms the diagnosis (though tissue staining may complicate subsequent exploration)
• Methylene blue swallow test / Gastrografin swallow - for pharyngocutaneous fistula
• Sialography - to assess parotid duct integrity; useful in deep penetrating injuries or when the wound cannot be easily explored; technically demanding (cannulation of the duct)
• Sialendoscopy - emerging technique; may facilitate identification of the site of duct injury and aid repair
• CT / MRI - rarely helpful in acute setting; CT angiography may be needed if vascular injury suspected
• Ultrasound - guides botulinum toxin injections

Management

Conservative (first-line)

1. Pressure dressings - reduces salivary collection and encourages closure from inside out
2. Repeated needle aspiration (especially for sialoceles) - can be repeated as needed
3. Nothing by mouth / dietary modification - reduces salivary stimulation
4. Antiseptic gauze packing of the fistula tract
5. Antibiotics - broad-spectrum coverage given the risk of infection in contaminated wound beds; culture-directed
6. Antiseptic oral rinse - 0.25% acetic acid by mouth (10 mL, 3-4 times daily) to "sterilize" the fistula from within
7. Anticholinergic agents to reduce saliva production:
   • Propantheline
   • Scopolamine
   • Glycopyrrolate
   • Tricyclic antidepressants (cholinergic blockade as a side effect)

Botulinum Toxin A (emerging adjunct)

• Direct injection into the parenchyma of the involved gland
• Ultrasound guidance recommended to limit side effects (masticator or facial weakness if injected too anteriorly)
• Increasing case reports with favorable outcomes, though no large controlled trials yet
• Used as adjunct to conservative therapy - Cummings Otolaryngology

Surgical Management (when conservative therapy fails)

• If missed duct injury is identified early (before significant fibrosis) - wound can be reopened and duct anastomosis attempted

• Within 72 hours: end-to-end anastomosis over a cannula/Silastic stent using fine monofilament sutures
• If duct tissue loss >1 cm: proximal end cannulated for marsupialisation into the oral cavity OR duct rerouting
• Extensive parenchyma + duct injury: ductal ligation + gland excision - Bailey and Love's Short Practice of Surgery, 28th Ed

• Salivary bypass tube - diverts saliva away from the pharyngeal defect; reduces incidence and severity of fistula; can be used at initial operation or postoperatively for high-output fistulas
• Pedicled muscle flap (pectoralis major, trapezius, or latissimus dorsi) - interposed between pharyngeal and skin defects; provides excellent blood supply and antibacterial benefit in an avascular, infected bed
• Combined anterolateral thigh free flap + salivary bypass tube for complex reconstruction
• Control of esophageal reflux is important in prevention and management

Complications of Untreated / Poorly Managed Fistula

• Impaired wound healing
• Wound infection and abscess
• Irregular scarring
• Salivary gland atrophy
• Fistula tract fibrosis making late repair more difficult
• Salivary bypass complications if untreated after laryngectomy (carotid blowout in irradiated patients)

Key Points for Exams

• Most common cause: post-parotidectomy (iatrogenic)
• Diagnosis confirmation: amylase in discharge fluid; methylene blue dye test
• Most fistulas close conservatively with pressure dressing ± anticholinergics
• Botulinum toxin A is an effective adjunct with growing evidence
• Sialendoscopy is the emerging tool for duct assessment
• Pharyngocutaneous fistula post-laryngectomy: pectoralis major flap is the workhorse for surgical closure
• In trauma: duct repair within 72 hours gives the best chance of primary anastomosis

Nasolabial Flaps

Definition

Anatomy and Blood Supply

• The superiorly based flap is supplied predominantly by the angular artery (superior labial and angular branches of the facial artery)
• The inferiorly based flap is supplied by inferior labial and submental branches

Types of Nasolabial Flaps

1. Nasolabial Transposition Flap

• A single-stage random-pattern transposition flap
• Used for alar crease, distal nasal sidewall, and lateral alar defects
• The flap is incised from the nasofacial sulcus, dissected, transposed, and the distal flap is aggressively defatted to recreate the alar rim contour
• When used for through-and-through alar defects, the flap can be folded on itself to reconstruct the inner lining and outer skin simultaneously
• A Burow's triangle (standing cone deformity correction) is excised on the nasal sidewall
• Cartilage strut graft (auricular cartilage) is placed along the alar rim and anchored with periosteal sutures to the undersurface of the advancing flap

2. Nasolabial (Melolabial) Interpolation Flap

• A two-stage procedure
• Used for large/complex alar defects, alar rim defects, nasal tip defects, and mid upper lip
• Stage 1: Flap is harvested from the nasolabial fold, a foil template of the contralateral ala is made and flipped; the flap is rotated downward, debulked, trimmed, and inset into the defect; the pedicle is left intact and wrapped with Vaseline/Xeroform gauze
• Stage 2 (at ~3 weeks): Pedicle is divided, the wound edges are freshened, tissue is further debulked, and remaining edge sutured; donor defect is closed up to base of pedicle

3. Island Nasolabial Flap

• Pedicled on perforating vessels; can be rotated 180 degrees to allow primary closure of the donor
• Useful where a skin bridge pedicle would be cosmetically unacceptable or impractical

4. Superiorly Based vs. Inferiorly Based

Indications

External (Cutaneous) Uses:

• Nasal ala - the primary and most common indication
• Alar rim - complex defects, especially with cartilage loss
• Nasal tip - moderate size defects when a forehead flap is less optimal
• Nasal sidewall - lateral alar crease
• Upper lip - mid upper lip defects; superiorly based hair-bearing flap for lateral lip cancer reconstruction in men
• Medial cheek defects

Intraoral / Head and Neck Uses:

• Floor of mouth reconstruction (tunnelled submucosally)
• Buccal mucosa defects
• Lower alveolus reconstruction following mandibular surgery
• Used as a lining flap for nasal reconstruction (inner layer of full-thickness alar defects)
• As part of composite nose reconstruction alongside forehead flaps

Surgical Technique - Key Steps

1. Defect assessment: Measure the defect; extend to include the entire alar cosmetic subunit for a better aesthetic result
2. Template creation: Make a foil/gauze template of the defect (or contralateral ala) and place on the ipsilateral nasolabial skin
3. Flap design: Mark the flap ellipse in the nasolabial fold; ensure adequate pedicle width at the base
4. Incision and dissection: Incise flap; dissect deep to subcutis to a well-vascularized pedicle; the flap is myocutaneous in its deep plane
5. Donor closure: Close the donor site in the nasolabial fold (primary closure, scar hidden in fold)
6. Cartilage support (if needed): Insert cartilage strut graft (auricular/septal) at the alar rim before flap insetting
7. Flap inset: Twist/rotate flap on pedicle; debulk and trim; suture into defect
8. Pedicle management: Wrap pedicle with non-stick gauze
9. Stage 2 (3 weeks later for interpolation flap): Divide and inset pedicle; further debulking and suture refinement

The Note Flap

The Reverse (Spear's) Nasolabial Flap

• Employed when the defect involves the entire ala including the junction of the lateral ala and cheek/upper lip
• The motion of this flap is an upward rotation - opposite to the traditional nasolabial interpolation flap
• Also called the "melolabial flap with a twist"

Advantages

• Excellent color and texture match with nasal and facial skin
• Abundant, redundant tissue in the nasolabial fold
• Inconspicuous donor scar hidden in the nasolabial fold
• Reliable, axial blood supply
• Versatile - can be used as transposition, interpolation, or island flap
• Can provide both outer skin cover and inner lining simultaneously (folded technique)
• Can be used with cartilage grafting for structural support
• Relatively simple technique compared to forehead flap

Disadvantages

• Two stages required for the interpolation flap (3-week interval)
• Hair-bearing skin in men limits use of superiorly based flap (may result in hair growth on the reconstructed ala)
• Limited reach for very large or medially located defects
• Bulky initially - requires secondary debulking in some cases
• Risk of pin-cushioning (trapdoor deformity) if not properly defatted
• Scar contraction may distort the alar margin if not planned carefully

Comparison with Paramedian Forehead Flap

Key Points for Exams

• Named for the nasolabial fold - the skin crease between nose/cheek and upper lip
• Blood supply: facial artery (via angular and labial branches)
• Most common use: alar reconstruction
• Superiorly based = greater reach; inferiorly based = better skin match, less hair
• Two-stage interpolation flap: pedicle divided at 3 weeks
• The Note flap = superiorly based nasolabial flap - one stage only
• Spear's/Reverse flap = for full alar defects - upward rotation
• Can be used intraorally by tunnelling submucosally for floor of mouth/buccal reconstruction
• For full-thickness alar defects: flap folded on itself OR combined with a second lining flap