By Nicholas Peiffer, M.D.
This lecture will be discussing various options the surgeon has in reconstruction of the head and neck. Furthermore, it will touch on some basic physiology and basic principles to keep in mind in these types of surgery, specifically patient goals and expectations as well.
To start, the following are some important dates in the history of reconstructive surgery in the head and neck.
In the year 2000 BC, records show the use of certain techniques for nasal reconstruction in India. Seeing that there was a common practice of nasal amputation for adulterers and enemies, there was a high need for this reconstruction. In 600 BC, we see the first use of the midline forehead reconstructive flap.
In the late 16th century, Tagliocozzi pioneered first pedicled upper arm flaps to the midface. In the 1920s, Gillies, commonly known as the father of head and neck reconstruction, made numerous advances on victims of war trauma. In the 1960s, the temporalis and deltopectoral flap were developed and became the workhorse of reconstruction. In 1976, McCraw et al, described macro/microanatomy blood supply to the skin of the face. Allowed flaps to be designed based on the blood supply.
Skin physiology is an important factor to take into consideration in reconstruction. The skin vascular supply performs two primary functions. One nutritional support. At baseline, the volume of flow is over 10 times that required for support. The second function is thermoregulation. Flow is estimated to vary 1000 fold by shunt manipulation. It is under the autonomic control of arteriovenous shunts. It is controlled entirely by the sympathetic nervous system.
The blood supply to the skin is as follows: Segmental blood vessels are large ‘named’ arteries running below muscle mass. They are the basis of the myocutaneous flap such as the pectoralis major or trapezius flap. They give off perforating vessels to the skin. Direct septocutaneous branches run atop the muscle and send branches to the skin. They have an axial pattern of flow. They are the supplementary blood supply to the skin. They are associated with at least one skin. They run parallel to skin and the blood supply is stable for the length of the vessel. Examples of flaps include the nasolabial and paramedian forehead. Musculocutaneous branches anastamose with the subdermal plexus and form a random pattern type of flap. They run perpendicular to the skin and are the dominant supply to the skin. The flap is limited by length and width.
Myers quoted “fresh flaps are always both viable and ischemic. A dynamic balance exists between the degree of ischemia and amount of time until recovery of nutrition. This determines flap failure or recovery. In 1982, Kerrigan looked at random and axial flaps in pigs. He determined a 13 hour average tolerance of total avascularity.
Some key components of flap survival are fixation of the flap by day 2 through a fibrin deposition layer. Neovascularization begins days 3 – 7 after transposition.
The first 48 hours can be a dangerous time for a flap. First, sympathetic discharge upon sectioning of a nerve causes a reflex release of catecholamines without reuptake. As a consequence, vasoconstriction and a decreased perfusion pressure results. Second, an overall inflammatory response is generated which initiates wound healing leading to increased tissue edema and decreased blood flow. Third, as catecholamines become depleted after approximately 12 hours, new oxygen becomes available and forms destructive free radicals. Hematomas have been postulated to a source of iron and therefore catalyst in radical formation. Finally, tension upon the wound, by larrabeet has been shown to have an inverse proportionality with survival. This is a more significant effect on large flaps.
Extrinsic factors can also have an impact on survival. Numerous studies have shown tobacco to decrease flap survival. The exact mechanism is unknown but theorized to be direct endothelial damage, vasoconstriction, and local concentration of prostaglandins. Radiation causes endarteritis obliteran and altered wound healing.
Other factors include atherosclerotic disease, diabetes, connective tissue disorders, nutrition, and thyroid function.
Some attempts have been made to investigate increasing flap survival. Allopurinol, superoxide dismutase to combat free radical formation. Hyperbaric oxygen therapy has been attempted to increase oxygen to the flap. Temperature manipulation has been used to alter metabolic demands of the flap.
Indirect and vasodilation methods.
Administration of angiogenic growth factors to promote neovascularization. Attempts have been made to increase random flap survival by altering the ‘width’ of the flap. This does NOT increase viability. Viability is determined by perfusion pressure against the critical closing pressure of arterioles in the subdermal plexus. Increasing the base increases the number of vessels not pressure.
The delay phenomenon has been the only method which appears to reliably improve flap survival. Four components are required for this phenomenon. Surgical trauma, majority of neurovascular supply eliminated, increased flap survival, and the benefit lasts up to six weeks. Theories include closure of Avshunts, improved blood flow by increased caliber and number, and ischemic conditioning. The technique is to raise the sides and undermine in random flaps leaving bipedicled ends. The common delay is 2 – 3 weeks.
In planning reconstruction always start with the simplest, safest method and escalate as dictated by the patient.
Primary closure to skin graft to local flap to distant flap.
Factors to consider include:
-general medical condition/malnutrition for shorter operative time/hospital course, one stage operation.
-tumor surveillance, if high concern for recurrence, may opt for method allowing observation such as skin graft
-wound healing, history of radiation/chemotherapy, full thickness coverage likely required
-PATIENT GOALS
The epidermis consists of keratinizing stratified squamous epithelium. The overall thickness ranges from 0.075 to 0.15mm. 80% of cells are keratinocytes.
The dermis has a thin papillary and thick reticular layer.
The eyelid is thinnest with <1mm and thickest on the back at >4mm.
Healing consists of three identified phases. First a fibrin layer anchors the graft within 8 hours. At 0 – 48 hours, imbibition takes place keeping the graft alive by diffusion of nutrition through the wound bed. After 48 hours, revascularization is initiated and becomes completed by day 7.
The split thickness skin graft consists of the epidermis and a variable amount of the dermis. Ranges in thickness from 0.008 to 0.018 inch. It has a good viability and does not require closure at the primary site. Often used to cover flap harvest site, floor of mouth, coverage over area for surveillance. Most common cause of failure is lack of immobilization.
The full thickness skin graft contains the entire epidermis and dermis. There is less contraction than the stsg, resists trauma, and has a better color match. There is a higher failure rate. They are commonly used in defects of the eyelid, nasal, and auricular defects.
Regional flaps
The deltopectoral flap is an axial based flap. It is based off the medial upper chest and horizontally oriented. Its arterial supply is off the first 3 – 4 perforators from the intercostals branches of the internal mammary a. It has a strong vascular supply and can be tubed for pharyngeal reconstruction. It requires a skin graft and a second procedure. If delayed it can be extended to the posterolateral deltoid or superior scapular spine. A cervical adaptation allows single stage reconstruction and good cosmesis.
The latissimus dorsi pedicled flap is an island pattern myocutaneous flap. Initially reported by Quillen in 1978. The arterial supply is the thoracodorsal artery. It provides a large amount of skin and soft tissue bulk and can reach to vertex of scalp with less hair transfer. Intraoperatively it requires repositioning and risk of venous vascular compression. There are high rates of skin graft failure. Free tissue transfer of flap often favored due to shortcomings.
The pectoralis major flap is the most widely used flap in head and neck reconstructive surgery. It is a myocutaneous flap based upon the pectoral branch of the thoracoacromial artery and lateral thoracic artery. It is a one stage procedure with excellent length reaching to the lateral canthus. It has strong vascular supply and is not technically challenging. It usually requires primary closure and the site is usually free of radiation. Minimal side effects exist such as possible pulmonary complications secondary to restriction and possible hair transfer to the face.
The trapezius flap allows harvest of three different myocutaneous flaps. Disadvantages include sacrifice of the transverse cervical in neck dissection, potential sacrifice of accessory nerve, special positioning, and the possible need for skin graft.
The superior trapezius myocutaneous flap is based off the upper 2/3 of the trapezius and the paraspinous perforators and occipital artery. It has a limited arc of rotation and a maximum extension of 10cm. A skin graft may be needed if the defect is greater than 10 cm. It is used primarily in posterolateral neck defects.
The lateral island trapezius flap is a myocutaneous flap based on the superficial branches of the transverse cervical artery.
The lower island trapezius flap is based upon the descending transverse cervical and dorsal scapular artery. It is the most versatile of the trapezius flaps and has a long pedicle.
Additional regional flap considerations include:
Sternocleidomastoid based upon the occipital, superior thyroid, and thyrocervical arteries. It is often used to close fistulas, augmentation, and vascular coverage.
The temporalis flap is based upon the anterior/posterior deep temporal arteries. It is often used for facial reanimation, soft tissue augmentation, and oral defects.
The pericranial flap is a loose areolar tissue axial and random based flap. The axial supply is off the supraorbital a. It is used for anterior fossa and lateral oropharyngeal defects.
Studies have shown the prevalence of microvascular trained otolaryngologists is becoming more commonplace.
There are more than 20 described free flap donor sites.
In general a 5 – 15% failure rate exists, usually within the first 72 hours. The salvage rate on re-exploration is 50 – 60%.
Advantages include a single stage procedure, potential two team approach, and possible functional restoration. Disadvantages include technical challenge and longer operative time.
The scapular free flap consists of a cutaneous or osseocutaneous flap. Its vascular supply is off the circumflex scapular artery. It usually incorporates the lateral scapula with direct bony perforators. It provides 8 cm good bone stock and can extend up to 14 cm with the medial scapula. Two separate skin/bone paddles can be harvested for good 3D contouring. Disadvantages include lateral decubitus positioning and disruption of the shoulder girdle.
The iliac crest flap consists of a segment of bicortical ileum, abdominal wall mm, and a cutaneous skin paddle. The vascular supply is by the deep circumflex iliac artery/vein. A total of 16cm bone can be harvested with extension to the sacro-iliac joint. Advantages include excellent bony reconstruction, allows dental rehab, and a concealed scar. Disadvantages include bulky soft tissue, risk of inguinal hernia, hip weakness, and a painful donor site.
The fibula free flap is a versatile flap with good bone stability, skin paddle coverage and minimal donor site morbidity. The vascular supply is based off the peroneal artery/vein. It requires preoperative MRA lower extremities to evaluate adequate runoff. 5% of the population has the peroneal artery as the major vascular supply to the foot. Complications include ligation of the posterior tibial artery and ankle instability if adequate fibula above lateral malleolus not preserved.
The radial forearm free flap is a fasciocutaneous or osseocutaneous flap based on the radial artery, venae comitantes. It is a great source of skin/soft tissue coverage for intraoral defects. It is applicable as a tube in pharyngoesophageal reconstruction. It can be harvested with the lateral antebrachial cutaneous nerve for sensory innervation. A preoperative Allen test or Doppler is required to assess adequate ulnar supply to the hand. The osseus component should be limited to 30 – 40% circumference to decrease the risk for pathologic fracture. The risk has been reported to be 15-20%.
The inferior rectus abdominus flap is a versatile soft tissue flap which can be used muscle only, musculosubcutaneous, musculocutaneous. Its vascular supply is based off the inferior epigastric artery/vein. It provides a large amount of soft tissue bulk, a long vascular pedicle, and is flexible. It has a risk for ventral hernia and is not a good color match.
The lateral thigh free flap is a fasciocutaneous flap based off the profunda femoris artery 3rd perforator.
The jejunal free flap is used in esophageal, long circumferential pharyngeal defects. It has a similar diameter, tolerates radiation, and has a native peristalsis. Negatives include an abdominal operation, small pedicle, uncoordinated peristalsis, high secretions, short ischemic time of less than 2 hours. The vascular supply is based off the superior mesenteric arcade.
Postoperative management
Anticoagulation
Dextran: branched polysaccharide, used for volume expansion during surgery. It has a colloidal osmotic force which draws fluid into intravascular space from interstitium which theoretically provides increased volume with lower viscosity. Disa in 2003 showed 100 pts undergoing free flaps with a 7.2 times greater risk of perioperative complications.
Heparin/LMWH
Heparin binds to antithrombin III which prevents fibrin formation, IV has immediate onset, SC 30min onset, and a half life of 1.5 hours.
LMWH inhibits factor X, less with ATIII. It has equal efficacy but increased bioavailability. It has a half life of 4.5 hours. The main risk is for hematoma formation. It is primarily used for DVT prophylaxis and less for direct flap management.
Aspirin/Ketorolac
Inhibits cyclooxygenase and preventing synthesis of thromboxane A2. ASA is irreversible while ketoroloc is reversible.
Fibrinolytics (streptokinase)
Primary use in threatened flap survival.
A study in 2007 by Ashjian showed no statistical difference between two arms for complications including bleeding, thromboembolism, and flap loss.
Flap Complications
Flap re-exploration rate is approximately 5 – 15%
It causes pedicle thrombosis, hematoma, and bleeding.
Kroll in 1996 looked at 990free flaps, 60% head/neck. Arterial thrombosis was 88% vessel related problems. After 1st 24 hours, venous thrombosis became the primary vessel related problem.
Chen in 2007 examined the timing of vascular compromis and outcome. Statistically better survival if incident after first 24 hrs. 82% presented within 24h, 96% after the first 72h.
In 2007 Bui reviewed 1200 free flaps and determined an early intervention <5hrs showed a statistically significant improved survival rate over delayed intervention. Head and neck reexplorations often was encountered up to 5 days postoperatively.
References
Baker, S. Local flaps in facial reconstruction. 2007.
Baily, B. Head and neck surgery – otolaryngology. 4th Edition. 2006.
Bui et al. Free flap reexploration: indications, treatment, and outcomes in 1193 free flaps. PlasticReconSurg. 2007. 119:7, 2092-2099.
Ashjian et al. The effect of Postoperative Anticoagulation on Microvascular Thrombosis. Annals of Plastic surgery. 2007. 59:1, 36-39.
Spiegel et al. Microvascular Flap Reconstruction by Otolaryngologists: Prevalence, Postoperative Care, and Monitoring Techniques. Laryngoscope. 2007. 117: 485-490.
Chen et al. Timing of Presentation of the First Signs of Vascular Compromis Dictates the Salvage Outcome of Free Flap Transfers. PlasticReconSurg. 2007.
Larson, D. Reconstruction in Head and Neck Cancer. American Academy of Otolaryngology Continuing Education.
Kroll, S et al. Timing of pedicle thrombosis and flap loss after free-tissue transfer. PlastReconSurg. 98: 1230, 1996.
