No abstract

Microsurgical free tissue transfer represents the mainstay of care in both ablative locoregional management and the simultaneous reconstruction of a defect. Advances in microsurgical techniques have helped balance the restoration of both form and function—decreasing the significant morbidity once associated with large ablative, traumatic, or congenital defects—while providing immediate reconstruction enabling early aesthetic and functional rehabilitation. There are a multitude of perioperative measures and considerations that aim to maximize the success of free tissue transfer. These include nutritional support, tight glycemic control, acknowledgment of psychological and psychiatric factors, intraoperative surgical technique, and close postoperative monitoring of the patients' hemodynamic physiology. While the success rates of free tissue transfer in experienced hands are comparable to alternative options, the consequences of flap failure are catastrophic—with the potential for significant patient morbidity, prolonged hospital stay (and associated increased financial implications), and increasingly limited options for further reconstruction. Success is entirely dependent on a continuous arterial inflow and venous outflow until neovascularization occurs. Flap failure is multifactorial and represents a dynamic process from the potentially reversible failing flap to the necrotic irreversibly failed flap—necessitating debridement, prolonged wound care, and ultimately decisions concerned with future reconstruction. The overriding goal of free flap monitoring is therefore the detection of microvascular complications prior to permanent injury occurring—identifying and intervening within that critical period between the failing flap and the failed flap—maximizing the potential for salvage. With continued technique refinement, microvascular free flap reconstruction offers patients the chance for both reliable functional and aesthetic restoration in the face of significant ablative defects. The caveat to this optimism is the requirement for considered perioperative care and the optimization of those factors that may offer the difference between success and failure.

The neck occupies the space between the clavicles and thoracic inlet inferiorly, to the base of the skull and inferior border of the mandible superiorly. The cervical part of the vertebral column provides the support for the skull above and strength and movement to the neck proper. The anterior neck provides passage for the major neurovascular supply to and drainage from the head, neck and intracranial region, transmits the upper aerodigestive tract and houses the thyroid and parathyroid glands. In the posterior neck a large mass of extensor musculature is situated posterior to the cervical vertebrae. Cranial nerves nine through twelve descend into the neck: nine (glossopharyngeal) and twelve (hypoglossal) meander towards the oropharynx and tongue, respectively; cranial nerve eleven (accessory) deflects backwards to supply the sternocleidomastoid and trapezius muscles whilst the tenth cranial nerve (vagus) wanders inferiorly within the carotid sheath between and posterior to the common carotid artery and internal jugular vein, before disappearing into the thoracic and abdominal cavities.

There are three paired major salivary glands of the head and neck, all named according to their location and each contributing to saliva and enzyme production via their respective ducts to assist with mastication and digestion. At rest, the lion’s share (60%) of saliva production is from the submandibular glands. On stimulation, the parotid contribution increases from 20% to 50%. There are up to 1000 minor salivary glands found within the submucosa of the oral cavity – 1-2mm in size and predominantly mucous in nature. The parotid glands are irregular shaped masses of lobulated tissue situated on the side of the face, reaching from the zygomatic arch superiorly to the upper part of the neck inferiorly where they overly the posterior belly of digastric and upper sternocleidomastoid muscle. Anteriorly, the gland lies between the posterior border of the mandibular ramus before continuing below the external acoustic meatus towards the mastoid process posteriorly.

The thyroid gland is a symmetrical H-shaped endocrine structure in the lower neck. It consists of two lobes, each extending from the oblique line of the thyroid cartilage above to the sixth tracheal ring below – united by a median isthmus covered by the anterior jugular veins. The small, (usually) paired and inconsistent parathyroid glands lie behind the lobes of the thyroid gland. They measure 6mm by 4mm by 2mm and are ordinarily four in number – two superior and two inferior. They are involved in the careful regulation of the body’s calcium levels. Both superior and inferior glands are ordinarily supplied by the inferior thyroid artery. Drainage is into the venous plexus on the anterior surface of the thyroid.