CHAPTER 20
Soft Tissue Injuries

Jason Jamali, Antonia Kolokythas, and Michael Miloro

Department of Oral and Maxillofacial Surgery, College of Dentistry, University of Illinois Chicago, Chicago, Illinois, USA

Stensen's Duct Repair

A means of reestablishing parotid salivary flow through a damaged or severed Stensen's duct (parotid duct).

Contraindications

Partial transaction with adequate salivary flow through the orifice of Stensen's duct
Intervention may be delayed in the medically compromised or unstable patient.

Parotid duct (Stensen's duct): The anticipated course of the parotid duct is predicted by drawing a line from the tragus of the ear to the mid-portion of the upper lip. Stensen's duct originates from the anterior portion of the parotid gland and continues anteriorly toward the anterior border of the masseter muscle. At the level of the masseter muscle, the duct courses medially piercing through the buccal fat pad and buccinator muscle before terminating at its papilla orifice within the buccal mucosa adjacent to the maxillary second molar. The length of the duct is approximately 7.0 cm. Both the zygomatic and buccal branches of the facial nerve may cross the path of Stensen's duct.

Parotid Duct Repair Technique

A thorough clinical examination is performed to evaluate facial nerve function as parotid duct injuries frequently occur in conjunction with facial nerve injuries.

The patient is placed under general anesthesia within an operating room. Short-acting paralytics are used to allow for further facial nerve stimulation with a nerve stimulator during the procedure. The patient is prepped intraorally and extraorally and draped to allow for full exposure of the facial wounds.

The facial wounds are debrided and irrigated with light pressure. Pulsatile irrigation is deferred in cases where the facial nerve is exposed or damaged.

Exploration of the wound is commonly performed with magnification (loupe vs. operating microscope).

The duct is cannulated intraorally via the orifice of Stensen's duct with an IV angiocatheter (Figure 20.5, Case Report 20.2), or a 16-gauge epidural catheter. Lacrimal probe dilation is typically necessary to enlarge the duct to accommodate a catheter (Figure 20.2, Case Report 20.1 and Figure 20.4, Case Report 20.2).
Saline or propofol (TEVA Pharmaceuticals, North Wales, PA, USA) is injected through the cannula while the wound is observed for leakage. Toluidine blue has been used in the past, but typically it obscures the remainder of the field for repair.
If present, the location of transection is confirmed, and an attempt is made to identify and cannulate the proximal end of the duct over the same cannula placed transorally, obturating the distal portion of the duct. A blue background may be placed for visual enhancement of the surgical field.
Primary anastomosis is performed over the cannulated ends of the duct using nonresorbable nylon (9-0, 10-0) or silk (7-0, 8-0) sutures.
For large segmental defects of the duct, microsurgical repair with interposition grafting may be considered. Donor veins include the facial vein, the saphenous vein, and veins from the forearm.
Distal ductal injuries may be treated through a fistulization procedure where the cannulated duct proximal to the injury is diverted intraorally and sutured to the buccal mucosa, creating a new orifice.
Proximal injuries closer to the duct and those with extensive parenchymal damage may be treated with ligation of the proximal stump. Salivary flow may be decreased using anticholinergic medications or low-dose radiation to the gland.
After definitive treatment of ductal discontinuity, the parotid capsule is closed in order to minimize sialocele formation. If extensive parenchymal damage is present, a drain is placed and sewed to the anterior skin edge of the wound.
The wound is irrigated and closed in layers, and a pressure dressing is applied for 48 hours.

images — **Figure 20.1.** Deep facial laceration involving the parenchyma of the parotid gland.

Postoperative Management

Pressure dressings are removed after 48 hours.
If present, drains are removed after 1 week.
The intraoral stent or catheter is removed after 2 weeks.

Complications

Sialocele and salivary fistula formation: May result from unidentified or incompletely repaired ductal injury, extensive parenchymal gland damage, or failure to adequately close the parotid capsule. Early management involves opening the anterior aspect of the wound and placing a drain, pressure dressings, repeat aspirations, anti-sialagogues, and anti-cholinergic medications. Late management includes botulinum toxin injections, tympanic neurectomy, parotidectomy, and low-dose radiation therapy.
Salivary gland hypofunction: In the event that parotid injury or ductal repair results in decreased salivary flow, artificial salivary substitutes, sialogogues, or cholinergic medications may be used to augment saliva production.
Facial nerve deficits: These should be followed with neurosensory testing in cases in which facial nerve function has been demonstrated to be intact, and only transient deficits are expected (neurapraxia and axontotmesis). With transaction injuries of the facial nerve (neurotmesis), repair is indicated.

Key Points

All deep facial lacerations involving the parotid gland should have the parotid duct cannulated in order to evaluate the integrity of Stensen's duct (Figure 20.2, Case Report 20.1).
Ductal injuries overlying the masseter muscle are most amenable to repair, whereas intraparenchymal ductal injuries are difficult to identify and repair. Distal ductal injuries may be treated with fistulization or redirection of the duct intraorally within the buccal mucosa.
The choice of ductal repair is dependent upon the location of injury and the ability to identify both proximal and distal ends of the parotid duct.
Delayed repairs may be complicated by sialocele formation and scar formation. Immediate primary repair is preferred.
Sialography may be used preoperatively to diagnose ductal injury. Sialography may also be used postoperatively to evaluate and monitor the status of the repair and function of the parotid gland.
Damage to the facial nerve must be ruled out with penetrating injuries to the parotid region.
All hard and soft tissue injuries require meticulous debridement and closure, with special emphasis placed on aligning the vermilion border of the lip if involved.

References

Demian, N. and Curtis, W., 2008. A simple technique for cannulation of the parotid duct. Journal of Oral and Maxillofacial Surgery, 66, 1532–3.
Lewkowicz, A.A., 2002. Traumatic injuries to the parotid gland and duct. Journal of Oral and Maxillofacial Surgery, 60, 676–80.
Liang, C., 2004. Reconstruction of traumatic stensen duct defect using a vein graft as a conduit: two case reports. Annals of Plastic Surgery, 52, 102–4.
Lim, Y.C., 2008. Treatment of an acute salivary fistula after parotid surgery: botulinum toxin type A injection as primary treatment. European Archives of Otorhinolaryngology, 265, 243–5.
Steinberg, M.J., 2005. Management of parotid duct injuries. Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology, 99, 136–41.
Sujeeth, S., 2011. Parotid duct repair using an epidural catheter. International Journal of Oral and Maxillofacial Surgery, 40, 747–8.
Van Sickels, J.E., 2009 Management of parotid gland and duct injuries. Oral and Maxillofacial Surgery Clinics of North America, 21, 243–6.
Von Lindern, J.J., 2002. New prosepects in the treatment of traumatic and postoperative parotid fistulas with type A Botulinum toxin. Plastic and Reconstructive Surgery, 109, 2443–5.

Complex Facial Laceration Repair

The repair of complex soft tissue trauma with debridement, irrigation, exploration, repair of involved structures, and layered closure techniques.

Indications

Closure of soft tissue lacerations and defects following traumatic injury
Limit scar contracture and soft tissue deformity
Minimize adverse aesthetic outcomes

Contraindications

Wound contamination
Medically compromised or unstable patients
Definitive closure may be delayed until associated fractures have been addressed

Anatomy

Scalp: Layers from superficial to deep include the skin, subcutaneous tissue, galea aponeurotica, loose areolar tissue, and pericranium.
Periorbital region: The lacrimal gland is located within the anterior aspect of the superior lateral orbit. Lacrimal secretions drain into the upper and lower lid medial puncta, which drain into the lacrimal canaliculi. The lacrimal canaliculi travel 2.0 mm vertically before coursing medially 6.0 mm toward the lacrimal sac. The lacrimal sac drains into the nasolacrimal duct before emptying into the inferior meatus of the nose, inferior to the inferior turbinate.

Technique

The patient is positioned for best access and visualization.
The wound is irrigated, prepped, and draped in a sterile fashion.
Local anesthesia containing a vasoconstrictor is injected within areas of tissue trauma. In areas of avulsive defects where local flaps will be utilized, lidocaine without epinephrine should be considered. Nerve blocks are used where possible (mental, infraorbital, and supraorbital or supratrochlear). Injection along the wound edges may help with hemostasis; however, care must be taken not to distort wound edges during closure.
The tissue injury is meticulously irrigated with sterile saline, and complete wound exploration and debridement is performed. Pulsatile pressure irrigation should be utilized for wound debridement unless facial nerve injury is suspected.
Vital structures are examined for damage and repaired accordingly (nasolacrimal duct, parotid duct, facial nerve, underlying fractures, and hematomas adjacent to cartilage).
Areas of obvious nonvital necrotic tissue are debrided to healthy bleeding tissue.
Large, avulsive defects require repair with local and regional flaps and/or tissue-grafting procedures.
Closure is performed in a layered fashion. The deeper layers are closed using buried resorbable sutures. A layered closure minimizes potential dead space and hematoma formation. Superficial layers are closed with eversion of the skin edges. The closure should avoid excess tension and strangulation of the tissues as evidenced by blanching of the wound edges. Care is taken to properly align important anatomic landmarks such as the vermillion border, the gray line of the eyelid, and the nasal sill.
Ointments and dressings may be applied after closure. Bolsters may be used following repair of ear lacerations to prevent hematoma formation.

Postoperative Management

Antibiotic coverage and tetanus prophylaxis may be necessary (dog and human bites).
Drains are removed after 48–72 hours or when drainage is minimal. Nonresorbable sutures are removed at 5–7 days after repair, followed by application of steri-strips if necessary. Scalp staples are removed 10–14 days after repair.
Avoidance of sun exposure and sunblock is recommended to avoid hyperpigmentation.
Scar massage and/or steroid injections will minimize hypertrophic scarring.

Complications

Hypertrophic scars: Hypertrophic scars are limited to the original scar borders. Treatment involves silicone sheeting, steroid injections, and/or dermabrasion (elevated scars). Scar revisions are performed 6–12 weeks after repair during maximum collagen remodeling. Small scars may be excised (after 6 months), while larger scars may require various soft tissue rearrangements such as Z-plasty, broken-line closure (W-plasty or geometric design repair), and local flaps (advancement, transposition, and rotation).
Keloid formation: Keloids extend beyond the original scar borders into the adjacent tissues. The incidence of keloids is increased in Fitzpatrick skin types III–VII (darker skin). Any excision or debulking of a keloid must be combined with other modalities to prevent recurrence. Steroid (triamcinolone) injections and silicone sheets may be used for this purpose.
Dyschromias: Minimized with avoidance of direct sunlight.
Depressed scars: Minimized with proper eversion of the wound edges during initial tissue reapproximation. Fat atrophy may contribute to the depression of scar tissues. Various implants and aesthetic skin fillers have been used, including alloderm, collagen, fat, and hyaluronic acid.

Key Points

All wounds are considered contaminated and must be thoroughly and meticulously irrigated and debrided. Foreign bodies (dirt, glass, and asphalt) not debrided will lead to wound infection, wound dehiscence, and flap necrosis.

All complex soft tissue lacerations should be explored to rule out injury to underlying vital structures (neural, vascular, canalicular, and/or ductal injury) prior to closure.

The scalp is highly vascularized and can be associated with significant blood loss over a short period of time (Figure 20.8). The scalp should be closed in a layered fashion to eliminate potential dead space (Figure 20.9).
Signs of lacrimal system dysfunction include persistent epiphora, conjunctivitis, and dacryocystitis. Lacrimal system damage is tested for by utilizing a dacryocystogram and a Jones I/Jones II test. The lacrimal drainage system can be repaired by establishing a new drainage system via a dacryocystorhinostomy. (See Figures 20.10 and 20.11.)
Avulsive injuries to the eyelids up to 25% can be closed primarily. Avulsive injuries to the eyelids of 25% or greater are repaired with tissue grafts (postauricular tissue) or local flaps.
An intranasal examination is performed in order to identify septal hematoma formation or avulsion with exposure of the underlying cartilage. Nasal hematomas present as reddish-bluish elevations of the nasal septal soft tissue and should be drained immediately with an incision parallel to the nasal floor. Packings, Doyle splints, or mattress sutures may be used after drainage to prevent the reformation of the hematoma.
All ear lacerations should have a complete otoscopic examination to evaluate the tympanic membranes (rupture and hematotympanum), lacerations involving the external auditory canal, and foreign bodies. External ear hematomas should be drained, and a pressure dressing placed. The ear has a tremendous vascular supply and can remain perfused with a small pedicle. Small areas of exposed cartilage are managed with antibiotic impregnated dressings. Large areas of exposed cartilage are managed with skin grafts.
The reestablishment of the vermillion border is the key step in repairing lip lacerations (see Figure 20.6, Case Report 20.1; Figures 20.12 and 20.13; and 20.18, Case Report 20.3). The closure of full-thickness lip lacerations begins from the inside (mucosa) out (skin). Avulsive injuries to the lips of up to 25% can be primarily closed. Defects greater than 25% will require local flaps to minimize microstomia.
Neck wounds are divided into three zones. Unstable patients require urgent explorations with general anesthesia. Stable patients require CT angiogram and possible esophagography depending on the zone and depth of injury (Figure 20.14).

References

Janfaza, P., 2011. Surgical anatomy of the head and neck. Cambridge, MA: Harvard University Press.
Persing, J.A., 2007. Soft tissue surgery of the craniofacial region. London: Informa Health Care USA.

Facial Nerve Injury Repair

A means of repairing traumatic injuries (complete transection) of the facial nerve with direct anastomosis or interposition grafting.

Indications

Traumatic injuries of the facial nerve along its extratemporal course associated with facial weakness or paralysis
Traumatic neurotmetic (transaction) injuries of the facial nerve
Facial nerve injuries proximal to a vertical line dropped from the lateral canthus are amenable to surgical repair. Distal nerve injuries are typically not repairable due to extensive nerve arborization and adjacent nerve recruitment

Contraindications

Intratemporal nerve damage
Neuropraxic or axonotmetic facial nerve injuries, with temporary paresthesia
Injuries >1 year old (due to muscle atrophy)
Bell's palsy or viral-related facial nerve weakness

Anatomy

Following its exit from the stylomastoid foramen, the main trunk of the facial nerve may be localized in relation to the following landmarks:

Tragal pointer (the nerve is located 1.0 cm deep and slightly anterior and inferior to the tragal pointer)
Attachment of posterior digastric muscle (the nerve is located superior to the medial attachment of the posterior belly of the digastric muscle)
Tympanomastoid suture (the nerve is located 5–10 mm caudal to the anterior aspect of the tympanomastoid suture)
Styloid process (trunk begins posterior before coursing lateral to the styloid process).

After coursing in an anterior-superior direction for 14.0 mm on average, the pes anserinus gives rise to the five branches of the facial nerve (temporal, zygomatic, buccal, mandibular, and cervical).

Technique

Under general anesthesia, the patient is positioned in a supine position with the head turned to the contralateral side. The neck is slightly extended.

The patient is prepped and draped in normal sterile fashion.

For immediate repair, access is obtained through the existing laceration. In cases of delayed repair, a modified Blair incision is utilized that combines a pre-auricular incision with a submandibular lazy “S” extension for complete exposure. After developing a sub-SMAS (superficial musculoaponeurotioc system) skin flap anteriorly, the main trunk of the facial nerve is located using the landmarks discussed in this chapter.

The tragal pointer is identified through a subperichondral dissection along the medial aspect of the tragal cartilage. After anterior-inferior blunt dissection, the nerve will be found 1.0 cm deep to the tragal pointer.

Alternatively, the trunk may be approached inferiorly. Retraction of the sternocleidomastoid muscle exposes the posterior belly of the digastric muscle, which is followed toward the digastric groove. The trunk will be found within this location at the depth of this plane superiorly.

Mobilization of the superficial aspect of the parotid gland will allow identification of the facial nerve proximally along its terminal branches. Additionally, a superficial parotidectomy may alleviate tension applied to the facial nerve across larger gaps of traumatic discontinuity.

The wound is explored, and the proximal and distal facial nerve ends are identified (Figure 20.16, Case Report 20.3). Damage to the parotid gland or Stensen's duct should be identified because sialocele formation may compromise the facial nerve repair.
With the aid of microscopy and a colored background (Figures 20.16 and 20.17, Case Report 20.3), adhesions are removed and the proximal nerve is interrogated with electrical stimulation. If no response is elicited, a neurotomy is performed. The Victor–Meyer neurotomy instrument is used to remove the damaged or scarred regions until a normal appearance of the nerve ends and fascicular pattern is encountered.
An end-to-end anastomosis is performed if the gap of discontinuity is small enough to allow for a tension-free nerve repair (Figure 20.17, Case Report 20.3). If significant tension is encountered, cable grafting (sural and greater auricular), jump grafts, crossover facial nerve grafting, allogeneic nerve grafts (AxoGen, Alachua, FL, USA), or nerve conduits (autogenous or alloplastic) may be considered.
The fascicular pattern of the facial nerve should be identified; epineurial suturing with nonresorbable sutures is sufficient in regions that have a monofascicular (one-fascicle) or oligofascicular (fewer than 10 fascicles) pattern.
Align and orient the nerve fascicles as best as possible (coaptation). If a fascicular or perineurial repair is chosen, the epineurium should be removed at the ends (~5.0 mm), and any protruding axons are trimmed.
With the epineurial repair, 8-0 nylon sutures are preferred. A tension-free repair is mandatory.
Confirm that the nerve fascicles remain properly oriented. This is easier in more proximal locations of the nerve where the diameter is greater. Begin with the placement of two sutures at 180° around the nerve periphery. Approximation is preferred over strangulation because overtightening of the sutures may result in twisting of the fascicles. Leave the initial suture ends long enough to allow manipulation of the nerve stumps during the remainder of the nerve repair.
The nerve is rotated to allow for suturing of the remainder of the epineurium. The number of sutures depends upon the diameter of the nerve; however, four sutures are typically sufficient.
The knots of the nonresorbable suture should be trimmed (1.0–2.0 mm).
The wound is closed in a layered fashion following wound irrigation.

Postoperative Management

An intensive postoperative regimen of aggressive physiotherapy with daily exercises is necessary to ensure proper motor reeducation.
Supportive eye care may be necessary (tear substitutes, lid taping, and gold weight placement).

Complications

Synkinesis: Defined as involuntary muscular movements occurring simultaneously with voluntary movements. Physiotherapy and biofeedback are started immediately. Botulinum toxin injections may be considered.
Exposure eye keratopathy: Treated with supportive eye care.
Sialocele: Treated with drainage and pressure dressings.

Key Points

Facial nerve injuries medial (distal) to a vertical line dropped from the lateral canthus do not require repair.
Immediate repair should be performed whenever possible. If, after confirmation of complete nerve transaction, a delayed repair is planned, the identified nerve ends should be appropriately tagged with nonresorbable suture to facilitate identification later.
Electrophysiologic (EP) testing (electromyogram [EMG]) is used to determine the prognosis of recovery in instances where nerve transection has not been verified. Accurate results from EMG may not be useful until up to 10–21 days post injury when fibrillation potentials appear.

References

Blanchaert, R.H., 2001. Surgical management of facial nerve injuries. Atlas of the Oral and Maxillofacial Surgery Clinics of North America, 9, 43–58.
Coker, N.J., 1991. Management of traumatic injuries to the facial nerve. Otolaryngologic Clinics of North America, 24, 215–27.
Davis, R.E., 1995. Traumatic facial nerve injuries: review of diagnosis and treatment. Journal of Cranio-Maxillofacial Trauma, 1, 30–41.
Janfaza, P., 2011. Surgical anatomy of the head and neck. Cambridge, MA: Harvard University Press.
Pather, N., 2006. Landmarks of the facial nerve: implications for parotidectomy. Surgical and Radiologic Anatomy, 28, 170–75.
Rovak, J.M., 2004. Surgical management of facial nerve injury. Seminars in Plastic Surgery, 18, 23–29.