Master Techniques in Otolaryngology - Head and Neck Surgery: Reconstructive Surgery, 1ed.

6. Management of the Partial Glossectomy Defect: Radial Forearm Free Flap

Kevin M. Higgins

INTRODUCTION

The radial forearm flap, remains a popular flap in the management and reconstruction of the partial glossectomy defect, especially where the base of tongue and suprahyoid musculature has been preserved, and reconstructive bulk is unnecessary (Fig. 6.1). Numerous studies have shown the utility afforded by the thin pliable nature of the fasciocutaneous radial forearm free flap (RFFF). It facilitates and maintains the mobility of the remaining oral tongue, which is of major importance for deglutition and articulation. Furthermore, the antebrachial cutaneous nerve of the forearm has sensory reinnervation capability using a microneural anastomosis with the lingual nerve that affords a high degree of sensory recovery and enhanced function.

FIGURE 6.1 An elevated radial forearm free flap.

The second most common site of oral cancer is in the mobile portion of the oral tongue, anterior to the circumvallate line. Patients with cancer of the oral tongue may present with odynophagia, often with referred otalgia, with or without dysarthria, and with dysgeusia. The cancer typically manifests as a noduloulcerative lesion affecting the lateral border of the tongue as the most common subsite with associated metastasis to levels 1, 2, 3, and occasionally 4. There is often an associated history of the long-term habits of smoking cigarettes, using smokeless tobacco, and drinking alcohol. Additional pertinent risk factors include human papillomavirus infection, chronic inflammatory conditions affecting the mucosal surfaces such as lichen planus, long-standing erythroleukoplakia, and poor oral hygiene.

A complete examination of the head and neck should be carried out with a combination of inspection, palpation, indirect mirror examination, and direct endoscopy. Careful visualization for any irregularities of the mucosal lining of the upper aerodigestive tract is critical in order to effectively map out the extent of disease and to examine for any suspicious coincidental synchronous primary cancers. An examination of cranial nerve function is important and should include ipsilateral tongue deviation with protrusion, loss of power, tone and bulk as well as any fasciculation seen with lower motor neuron lesions is vitally important. Examination of the status of the dentition for obvious caries, loose teeth, root exposures, and gross gingival involvement or periodontal disease should be undertaken. An assessment of sensation of the teeth of the lower arch and the lower lip is important for assessment of trigeminal nerve function. In addition, palpation of the lesion is critical in order to assess the depth of invasion, relationship to the floor of the mouth, midline tongue raphe, and base of the tongue. Finally, one should carefully palpate the cervical nodal basins especially levels 1, 2, and 3 that are the primary echelon lymph nodes for metastasis from a primary cancer of the oral tongue. A neck dissection is usually carried out that may impact the reconstruction options or technique.

As with other head and neck malignancies, cancer of the oral cavity must be staged according to the American Joint Committee on Cancer TNM staging system. In general, surgery is the recommended first-line treatment for cancer of the oral tongue. Patients in whom surgery is contraindicated may have the options of brachy therapy or external beam radiation therapy.

Contraindications for surgical management with the RFFF include inability to tolerate anesthesia due to medical illness, a negative Allen test, or patient refusal.

A detailed metastatic survey with computed tomography (CT) with contrast of the head/neck and chest is routine. The CT is widely used to assess for bone invasion and cervical lymph node metastasis, while magnetic resonance imaging can complement CT scanning by providing better visualization of soft tissue structures, invasion of the tongue musculature, and extension to the base of the tongue as well as perineural invasion.

During the preoperative planning phase, testing the vasculature of the nondominant hand can provide information on the viability of the donor hand following RFFF transfer. This is assessed with the Allen test to ensure patency of the ulnar and radial forearm vessels but more importantly to ensure adequate anastomotic channels and completeness of the superficial and deep palmer arches (Fig. 6.2). Anatomic variants such as the superficial ulnar artery and incomplete palmar arches are extremely uncommon. If the Allen test is equivocal, a pulse oximeter can be placed on the thumb or index finger (the digits at greatest risk for potential ischemia with anatomic variants) and an arterial pressure trace observed. Significant flattening and loss of the anacrotic notch (normal triphasic pattern) should prompt formal digital plethysmography or a search for another reconstructive flap option such as the anterolateral thigh or lateral arm flap.

FIGURE 6.2 The modified Allen test. A positive test is demonstrated by reperfusion of the palm within 7 to 10 seconds of release of pressure on the ulnar artery. A negative test is demonstrated by lack of reperfusion within 7 to 10 seconds and indicates poor collateral ulnar circulation to the hand.

Office-based duplex ultrasonography is becoming increasingly performed by head and neck surgeons. This technology allows a detailed assessment of cervical node status and availability and location of suitable recipient vessels in the neck, and with a fingertip probe, an assessment of the depth of invasion. In addition, it can facilitate the ability to perform US-guided fine needle aspirations.

Oral cavity defects can often be approached transorally with the exposure maximized by the judicious use of multiarmed retractors such as the Dingman Gag (Fig. 6.3). Retraction sutures inserted into the remaining tip of the tongue and dorsum help to facilitate triangulation for excision and insetting of the flap. Novel techniques such as transoral robotic surgery also have a role in primary ablative surgery, with robotic assistance in the insetting of more posteriorly located defects that can potentially minimize the need for mandibular swing or lingual release approaches that tend to add to overall patient morbidity and length of stay. An additional key consideration is hemostasis after completing the ablation. Lingual vessels should be controlled with vascular clips and bipolar cautery or other novel closure systems such as the harmonic scalpel or Ligasure™ device. A Valsalva maneuver to 30 cm H₂O allows for the identification of occult venous bleeding that could open up with buried inset, causing flap compromise with a hematoma of the floor of the mouth and potential compromise of the oral airway. Oozing from the defect can be controlled with Surgicel that can be combined with recombinant thrombin to enhance the hemostatic effect. A moistened laparotomy sponge is left in the oral cavity while the flap is harvested. One potential pitfall is the access to the neck recipient vessels. It often helps to divide a portion of the mylohyoid muscle to avoid potential strangulation of the microsurgical pedicle. The tunnel should be enlarged with serial dilatation to allow easy accommodation of at least two gloved fingers and maintained with a moistened 1-inch Penrose drain.

FIGURE 6.3 The Dingman retractor provides exposure for transoral reconstruction.

The RFFF is designed based on the dimensions of the defect in the tongue. It is extremely important to avoid overfilling the defect as it negatively impacts mobility and requires secondary debulking procedures. One should not measure the defect based on the ablative dead space volume as it typically overestimates the overall requirement. This is especially true when the jaw has been split and swung open with a mandibulotomy approach. A foil template can be fashioned based on the resection specimen and unfolded on the forearm to allow for two-dimensional mapping. I routinely use an overflow cylinder with a modified Archimedes technique to obtain a volume measurement as well that helps to ensure overall like-for-like volume matching (Fig. 6.4). The nondominant forearm is selected. The palpable radial arterial pulse line is marked, as is the course of the superficial cephalic vein. The arm should be free draped and the flap harvested ideally under tourniquet control. An Esmark bandage can be wrapped from distal to proximal around the forearm prior to cuff inflation to exsanguinate the forearm, while other authors prefer to leave some blood in the vascular channels to aid in their identification and control. The tourniquet is then inflated with the hand elevated to 250 mm Hg. The flap design should ideally allow the pedicle to exit either posteriorly or inferiorly. Smaller defects (typically <3 cm × 3 cm) can be incorporated into an ulnar “hatchet”-style flap to avoid skin graft coverage (Fig. 6.5). The long axis of the flap needs to be oriented in a transverse direction to facilitate a hatchet flap closure of the distal wrist crease margin. Additional local bilobed flaps based on ulnar septocutaneous perforators can also be designed. These local flaps have been shown to prevent donor site morbidity especially as it relates to overall wrist mobility; however, they may complicate exposure of the pedicle.

FIGURE 6.4 The Archimedes volume displacement technique is used to determine the approximate volume of the radial forearm free flap.

FIGURE 6.5 RFFF donor defect can be corrected with an ulnar hatchet flap.

The flap can be raised in either the suprafascial or subfascial plane. Suprafascial technique and elevation protects the paratenon and helps enhance skin graft take; however, for novice surgeons, it can endanger the septal perforators that are extremely small yet numerous, as the intermuscular septum is approached from the radial and ulnar direction between the flexor carpi radialis and the brachioradialis. It is ideal to incorporate the cephalic vein in the flap design and elevation. Even if it seems divergent based on the superficial anatomical course, one is typically able to capture a side branch draining the flap distally toward the wrist crease. This facilitates microvascular anastomosis in that the cephalic vein usually affords a 3- to 4-mm vessel caliber, whereas the major vena comitans that accompanies the radial artery is seldom larger than 2.5 mm unless a communicating branch between the deep and superficial venous system is traced proximally toward the antecubital fossa. The radial sensory nerve has to be preserved throughout its forearm course as damage to it can result in problematic dermatomal deficits and potentially traumatic neuromata. It is carefully protected as it emerges beneath the brachioradialis muscle belly and courses over its tendon. It typically ramifies in close proximity to the cephalic vein, and its most medial branch is often intimate to the microsurgical pedicle and the delicate septocutaneous perforators to the skin paddle. However, despite these anatomical challenges, it seldom if ever requires sacrifice with jeweled microsurgical instruments and a nerve clinging technique, to safely separate the most medial branch from the microsurgical pedicle.

Different authors advocate elevation of subcutaneous adipose tissue along with the antebrachial fascia to protect the pedicle from salivary contamination or neck cutaneous breakdown in postchemoradiation salvage operations. This bulk is not a problem with large volume defects with mandible swing approaches. For smaller transoral approaches, this added bulk can cause strangulation of the flap in the floor of the mouth tunnel. It is safer to restrict the pedicle to the cephalic vein, antebrachial cutaneous nerve of the forearm, and the radial artery and its minor and major venae comitantes in this situation. Harvesting the flap can be accelerated with automatic clip appliers or clamp, seal, and cut devices such as the LigasureTM and Harmonic FocusTM. The pedicle is most safely approached from ulnar and radial as opposed to a distal-to-proximal dissection technique. This allows release of the flexor retinaculum, protection of the median nerve, and avoidance of delicate septocutaneous perforator destabilization by inadvertent suprafascial dissection planes that can be inadvertently developed by novice surgeons. In addition, the deep periosteal branches in the area of the radial styloid can be ligated more easily as they are seen earlier or can be more readily incorporated into an osteocutaneous flap design. As the pedicle is dissected toward the antecubital fossa, it is often helpful to follow the venae comitantes toward a confluent common vena comitans, which is typically seen at the emergence of the communicating branch. This dissection can be tedious as there are multiple deep perforator branches into the deep flexor muscles such as the pronator teres. This additional dissection is obviated with a reliable and robust cephalic vein that is draining the marked skin paddle. The tourniquet is deflated and the pedicle copiously irrigated with warmed heparinized saline solution and carefully inspected along its length and along the undersurface of the skin paddle for any obvious bleeding points. An exhaustive search for bleeders from the forearm donor site is also undertaken at the same time. Color and capillary refill are then observed in the hand and especially in the area of the thenar eminence. The flap should be allowed to drink for 10 to 15 minutes after primary ischemia time to minimize reperfusion injury after secondary ischemia and microsurgical anastomosis. This gives the surgeon time to comfortably prepare the recipient vessels for anastomosis. The facial artery and common facial vein are typically the best size match for the radial artery and cephalic vein or major vena comitans. The vessels should be prepared under loupe magnification with vessel dilatation and excess adventitial trimming. Approximating microvascular clamps are very helpful in maintaining vessel orientation during anastomosis. The harvested flap is then detached by interrupting arterial inflow first and allowing the venous blood to run out prior to venous clamp and tie. A surgical marker should be used to draw a straight vertical line along the pedicle axis. This allows any helical spiraling to be identified as the pedicle is drawn through the premoistened 1-inch Penrose drain into the neck. Careful insetting is then performed. It is often helpful to leave the ends of each previously placed suture long in order to facilitate traction and to avoid any fistula created by buried suture material. The anterior sutures often need to be left long and parachuted after any locking low-profile titanium plate is replaced. Circumdental sutures should be considered laterally, as the floor of the mouth mucosa is extremely thin and prone to tearing. Microvascular anastomosis is then undertaken with an operating microscope with 9-0 or 10-0 microsurgical nylon material (Fig. 6.6). An anastomotic coupler device, such as the 3 M Unilink, can be used to reduce anastomotic time (Fig. 6.7).

FIGURE 6.6 Microvascular vessel clamps allow for suturing the vessels together.

FIGURE 6.7 An anastomotic device (3 M Unilink) can be used to expedite connection of microvascular vessels.

Care should be taken with arterial coupling as it requires generous arterial vessel caliber, greater than 2.5 mm, and stiff atherosclerotic vessel walls often tear or pop off the ring pin collars. Once the microsurgical clamps are removed, visible thrill and palpable pulse should be confirmed. Venous strip test should be performed with microsurgical dilator instruments to demonstrate complete microsurgical loop with anterograde venous runoff, and then finally, the flap should be scratched to examine for bright red bleeding with delay of 1 to 3 seconds commensurate with capillary refill. Excess pedicle length can become dependent and kink, and this should be avoided with stay sutures or microsurgical clips to keep the pedicle in an appropriate resting position. Once the vessels are reapproximated, the neck and arm are reapproximated with layered closure. I routinely employ a suction drain system with care to place the suction away from the microsurgical pedicle. Fast-dissolving sutures such as Vicryl Rapide can be used to secure the suction drain away from the microsurgical pedicle, with Gelfoam slabs also being used to protect the microsurgical anastomoses.

As with management of other free flaps, clinical bedside check is essential in the immediate postoperative period for detecting flap failure. For the intraoral tongue flap, this includes assessing flap color, capillary refill, and any dehiscence of the incision line.

After the initial postoperative period, frequent close surveillance of patients for the first 3 to 5 years posttreatment is currently being advised. Postoperative imaging can be obtained if clinically indicated, and patients should be educated of any signs and symptoms of tumor recurrence, such as hoarseness, pain, dysphagia, referred otalgia, oral bleeding, and enlarged lymph nodes.

As with other operations, the risk of bleeding and infection is present. Hematoma in the neck needs to be carefully managed and a low index of suspicion for vascular pedicle compromise as being the cause with venous outflow obstruction. There are also risks of loss of tongue function, including airway obstruction, dysarthria, dysphagia with impaired oral preparatory, and oropharyngeal initiation of a functional swallow (temporary G-tube dependence), as well as free flap failures. With the radial forearm flap, the issue with flap compromise tends to relate to geometry issues with a long redundant pedicle causing kinking or helical twisting of the venae comitantes or a tight floor of the mouth tunnel causing strangulation of the venous outflow rather than arterial compromise as the intimal diameter with the radial artery and the facial artery or superior thyroid is usually 2.5 to 3 mm.

The tongue remains a difficult structure to reconstruct in the oral cavity, given its central role in articulation, deglutition, and airway protection. In this chapter, I have highlighted the microvascular techniques for RFFF reconstruction of a partial glossectomy. The RFFF is robust and versatile. In one comparison between the RFFF and the anterolateral thigh flap, there were no reported differences in speech intelligibility, tongue mobility, or deglutition scores.

• Depending on the location and size of the defect, there is typically a floor of the mouth component that needs to be managed to effectively seal off the oral cavity from the neck compartment. Separation of the floor of the mouth subunit from the lateral and ventral tongue surface is also important in maintaining overall tongue mobility and, in particular, to facilitate tongue protrusion.

• These goals of separation and seal are facilitated with a bilobed design with a longer curvilinear lobe for the dorsum and tip and the shorter lobe for the floor of the mouth (Fig. 6.8A and B).

FIGURE 6.8 A, B. Bilobed flaps allow for reconnection of the tongue and floor of the mouth.

• Additional bulk to fill in the tongue and restore some bulk to the base of the tongue if necessary or to recreate the tongue mound can be achieved with an additional “beaver-tail” modification with the additional forearm adipose tissue and fascia placed in a jelly-roll configuration under the skin paddle.

• Issues involving skin graft take can be mitigated with careful preservation of the paratenon investing the forearm tendon sheathes.

• Placement of the skin paddle more proximally over the forearm muscle bellies results in less tendon exposure. This does have the drawback of shortening effective pedicle length.

• Bolster dressing application and effective volar forearm splinting in the position of function also assist in minimizing shearing forces. Adjunctive measures such as application of platelet-rich plasma and VAC dressing application are currently being investigated by several groups, especially with problematic donor sites.

• If there are issues with reperfusion of the flap or forearm donor site, the following sequence should be followed; one needs to ensure that the patient is normothermic and has sufficient perfusion pressure. Hemoglobin and hematocrit should be optimized. Pulsed irrigation with papaverine should be used to combat and counteract vasospasm. Trial evidence and experimental model would suggest limited effect on sympathectomized free flaps with inotropic support in order to optimize overall perfusion pressure once volume has been expanded. I use ephedrine and dopamine and avoid selective alpha agonists such as phenylephrine. On very rare occasions, an interposition vein graft may be required to replace the transplanted radial artery.

• Basic neck tray

• Armoured/flexible endotracheal tubes that are low profile and keep the anesthetic circuit out of the operative field (adult number 7 or 8)

• Mouth gags (Davis, Dingman, props)

• Spandex self-retaining double-lip retractor

• Dental set (periosteal elevators, gouges, extractors)

• 2.0 low-profile mandibular locking plating system (if mandibulotomy is required)

SUGGESTED READING

Guofan Y, Baoque C, Yuzhi G, et al. Forearm free skin flap transplantation. Natl Med J China 1981;61:139–141.

Soutar DS, McGregor IA. The radial forearm flap in intraoral reconstruction: a versatile method for intra-oral reconstruction. Br J Plast Surg 1983;36:1–8.

Dubner S, Heller KS. Reinnervated radial forearm free flaps in head and neck reconstruction. J Reconstr Microsurg 1992;8:467–468.

Genden EM, Desai S, Sung CK. Transoral robotic surgery for the management of head and neck cancer: a preliminary experience. Head Neck 2009;31:283–289.

Mukhija VK, Sung CK, Desai SC, et al. Transoral robotic assisted free flap reconstruction. Otolaryngol Head Neck Surg 2009;140:124–125.