CC-BY-NC 3.0 PARTIAL GLOSSECTOMY FOR CANCER

Johan Fagan

Cancers of the tongue are generally treated of the tongue and FOM has with primary surgical resection. Adjuvant a covering of delicate oral mucosa through irradiation is indicated inter alia for ad- which the thin walled sublingual/ranine vanced tumours, tumours with perineural are visible. The frenulum is a mucosal invasion (PNI) or uncertain/close margins. fold that extends along the midline between the openings of the submandibular ducts Resecting tongue cancer without con towards the tip of the tongue (Figure 2). sidering subsequent oral function may severely cripple a patient in terms of speech, mastication, oral transport and swallowing. Resecting the anterior arch of the mandible Ranine veins beyond the midline without reconstructing Frenulum bone and with loss of the anterior attach- Puncta of submandibular ducts ments of the suprahyoid muscles (digastric, geniohyoid, mylohyoid, genioglossus) leads Submandibular duct to an Andy Gump deformity with loss of Figure 2: Anterior tongue and FOM oral competence, drooling, and a very poor cosmetic out-come (Figure 1). Posterolaterally the tonsillolingual sulcus separates the tongue from the tonsil fossa. Posteriorly the vallecula separates the base of tongue from the lingual surface of the ep- iglottis.

The mucous membrane covering the tongue and FOM varies in thickness and quality; this has relevance in terms of ob- taining surgical margins and retaining tongue mobility. The undersurface of the tongue has a thin, smooth, pliable mucous membrane. The mucous membrane cover- ing the anterior 2/3rds of the dorsum is thin Fig- and quite smooth and adherent to the ure 1: Andy Gump deformity tongue muscle compared to the mucosa covering the base of tongue (BOT) behind Surgical Anatomy foramen caecum and sulcus terminalis which is rough, thick and fixed to the un- The tongue merges anteriorly and laterally derlying muscle and contains a number of with the floor of mouth (FOM), a horse- lymphoid follicles (lingual tonsil). With shoe-shaped area that is confined peripher- BOT tumours it is therefore difficult to de- ally by the inner aspect (lingual surface) of termine the edge of a tumour making frozen the mandible. Anteriorly the undersurface http://openbooks.uct.ac.za/ENTatlas 34-1 Open Access Atlas of Otolaryngology, Head & Operative Surgery section especially useful to assess resection Vasculature margins. The tongue is a very vascular organ. The ar- The tongue comprises eight muscles. Four terial supply is derived from the paired lin- extrinsic muscles (genioglossus, hyoglos- gual and its branches (ranine ar- sus, styloglossus, palatoglossus) control the tery, dorsalis linguae, and sublingual ar- position of the tongue and are attached to teries) (Figures 6, 7); and the mylohyoid and bone (Figure 3, 4); four intrinsic muscles submental arteries. Additional blood sup- modulate the shape of the tongue, and are ply to the tongue emanates from the tonsil- not attached to bone. Below the tongue are lar branch of the facial and the as- the geniohyoid and the mylo-hoid muscles; cending pharyngeal artery. the mylohyoid muscle serves as the dia- phragm of the mouth and separates the tongue and FOM from the submental and submandibular triangles of the neck (Fig- ures 3, 4, 5).

Figure 5: Geniohyoid and mylohyoid

Figure 3: Extrinsic tongue muscles (palatoglossus not shown)

Genioglossus Figure 6: XIIn accompanied by ranine veins Vallecula Geniohyoid Mylohyoid Hyoid

Figure 4: Midline sagittal view of tongue

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when the surgeon elevates the submandib- ular gland from the lateral surface of the Tonsillar artery mylohyoid (Figures 8, 9). It branches off the inferior alveolar artery just before it enters the mandibular foramen, crosses the mylo- hyoid, and disappears anteriorly behind the digastric. It has connections with the sub- Ranine artery mental artery and via a defect in the mylo-

Sublingual artery hyoid with the sublingual artery in the

Lingual artery FOM. Figure 7: Dorsalis linguae artery Venous drainage is via lingual and ranine The lingual artery originates from the ex- veins. The lingual veins originate on the ternal carotid between the superior thyroid dorsum, sides, and undersurface of the and facial arteries and courses obliquely for- tongue and accompany the lingual artery wards and medial to the greater cornu of the and joins the internal jugular . The ra- hyoid (Figures 6, 7). It then loops downward nine veins originate below the tip of the and anteriorly and passes medial to hypo- tongue and are visible on its ventral surface; glossal nerve (XIIn) and the stylohyoid they accompany the XIIn as venae comitan- muscle. It then courses directly anteriorly tes and either join the lingual vein or pass and deep to the and finally as- lateral to hyoglossus to join the common fa- cends submuco-sally on the undersurface of cial vein (Figures 2, 6). the tongue as far as its tip as the ranine ar- tery (profunda linguae); it lies to either side of the genioglossus, and is accompanied by the lingual nerve. Two or three small dor- Submental artery sales linguæ arteries arise beneath the hyo- Mylohyoid muscle glossus and ascend to the posterior part of Mylohyoid artery the dorsum of the tongue and also supply Facial artery the mucous membrane of the posterior Figure 8: Fa- FOM, and oropharynx (Figure 7). The sub- cial artery emerges from behind posterior belly of di- lingual artery branches from the lingual ar- gastric (removed), and gives rise to a few branches in- cluding submental artery tery at the anterior edge of the hyoglossus and runs forward between the genioglossus and mylohyoid and supplies the sublingual salivary gland and mucous membrane of the FOM and gingiva (Figure 7). A branch of the sublingual artery pierces the mylohy- oid muscle and anastomoses with the sub- mental branch of the facial artery in Level 1b of the neck. The submental branch of the facial artery courses along the inferior, in- Figure 9: Mylohyoid artery is a branch of the inferior alveolar artery ner margin of the mandible (Figure 8). The mylohyoid artery and vein are encountered http://openbooks.uct.ac.za/ENTatlas 34-3 Open Access Atlas of Otolaryngology, Head & Neck Operative Surgery

Innervation ures 10, 11), oral component of submandib- ular salivary glands (Figures 10, 11), and the Other than palatoglossus which is innerve- lingual and XIIns. The paired sublingual ted by the Xn, all intrinsic and extrinsic salivary glands are located beneath the mu- muscles are innervated by the XIIn. The cosa of the anterior floor of mouth, anterior IXn provides somatic afferent and taste sen- to the subman-dibular ducts and above the sation to the posterior 1/3 of the tongue. mylohyoid and geniohyoid muscles (Fig- The lingual nerve provides general somatic ures 10, 11). The submandibular duct is lo- sensation to the anterior 2/3 of the mouth cated immediately deep to the mucosa of and FOM; taste is provided by the chorda the anterior and lateral FOM, and opens tympani branch of the VIIn via the lingual into the oral cavity to either side of the fren- nerve. The lingual nerve crosses deep to the ulum (Figures 2, 10, 11). submandibular duct in the lateral floor of mouth (Figures 10, 11). In the anterior FOM The mandible borders the FOM, and may it is located posterior to the duct (Figure 11). have to be divided for access (mandibu-lot- omy), or resected if involved by tumour (al- veolectomy / marginal mandibulectomy / Lingual nerve segmental mandibulectomy / hemimandi- Sublingual gland bulectomy). Important surgical features are Submandibular duct the position of the mental foramina through Submandibular gland which the mental nerves exit to innervate Mylohyoid muscle the lower lip; the mylohyoid line to which Geniohyoid muscle the mylohyoid muscles attach, the attach- Figure 10: Su- perior view of FOM, sub-mandibular gland and duct, ment of the genioglossus, and when plan- lingual nerve and mylohyoid and geniohyoid muscles ning marginal mandibulectomy, the height of the body of the mandible and the depths of the dental roots (Figures 12a, b). Lingual nerve

Submandibular duct

Sublingual gland

Submandibular gland

Mylohyoid muscle

Figure 11: In- traoral view of left sublingual gland with ducts of Rivi- nus, submandi-bular gland and duct, lingual nerve and mylohyoid muscles

Structures surrounding the tongue Figure 12a: Attachments of muscles to outer aspect of The following structures are located be- mandible and location of mental foramen tween the mucosa and the mylohyoid mus- cles: paired geniohyoid muscles in the mid- line (Figure 4); sublingual salivary glands (Figures 10, 11), submandibular ducts (Fig- http://openbooks.uct.ac.za/ENTatlas 34-4 Johan Fagan

o Avoid obstruction of subman- dibular ducts o Attempt to preserve lingual and XII nerves o Maintain mandibular continu- ity and strength o Maintain dental occlusion o Restore dentition

Figure 12b: Attachments of mylohyoid, geniohyoid, The author advocates elective neck dissec- genioglossus and digastric muscles to inner aspect of tion (END) Levels I-IV for squamous cell mandible carcinoma of the oral tongue that is >4mm thick and/or >T2 stage; a useful rule of In older, edentulous patients the mandible thumb is that a tumour which is clinically resorbs and the mental foramen and infe- palpable is likely to have a tumour thickness rior alveolar nerve may be very close to its that warrants END. BOT cancers and tu- superior surface (Figure 13). Marginal man- mours of the anterior FOM that approach dibulectomy may also not be possible in the midline require bilateral END. such a resorbed mandible due to the lack of residual bone. The remainder of this chapter will focus on the surgery of cancer of the oral tongue.

Preoperative evaluation

Mental foramen 1. Are there synchronous primaries, cervi- cal or distant metastases? CXR or CT chest and panendoscopy. 2. Is the tumour resectable? It may be dif- ficult to assess the extent of the primary cancer due to pain, tenderness and tris- mus; if in doubt, a patient requires im- Figure 13: Position of mental foramen in a resorbed aging such as CT/MRI, or examination mandible under anaesthesia. Other than cancers Surgical Objectives that extend posteriorly to involve the in- fratemporal fossa or involve the carotid • Adequate resection margins sheath, most tongue cancers are resec- • Preserve at least one lingual artery to table provided suitable reconstructive avoid infarction of tongue surgery can be done. • Avoid postoperative orocervical fistula 3. Is there evidence of perineural invasion • Optimise cosmesis and function (PNI) of major nerves? Examine the pa- o Maintain length and mobility of tient for neurological deficits of the tongue XIIn, mental, inferior alveolar and lin- o Avoid pooling of secretions and gual nerves. Widening of the alveolar food http://openbooks.uct.ac.za/ENTatlas 34-5 Open Access Atlas of Otolaryngology, Head & Neck Operative Surgery

canal on mandibular orthopantomogra- Panorex so as to predict whether a free phy (Panorex) may be seen with in- bony composite flap would be required volvement of the inferior alveolar nerve. to strengthen the remaining mandible. MRI may demonstrate PNI. Should Once cortex is invaded, then either mar- there be evidence of PNI then the af- ginal or segmental mandibulectomy is fected nerve is dissected proximally un- required. Medullary invasion requires til a clear tumour margin is obtained on segmental or hemimandibulectomy frozen section. that includes at least a 2cm length of 4. Is reconstruction required? A key con- mandible on either side of the tumour. sideration is surgical morbidity relating 8. Is a tracheostomy required? One should to cosmesis and function; this in turn is have a low threshold for tracheostomy. dependent on the available reconstruc- Only patients with small tumours may tive options. not require a tracheastomy. Whenever 5. Can the patient tolerate aspiration? the anterior laryngeal support of the Major resections and reconstructions, mylohyoid, geniohyoid and genioglos- especially if followed by chemoradia- sus muscles is lost, and especially when tion, may be complicated by variable a flap is used to reconstruct a defect, the measures of dysphagia and aspiration. patient is at risk of airway obstruction Physical fitness, pulmonary reserve, and and should have a temporary tracheost- cognitive function should therefore be omy. considered when selecting patients for such major resections. Anaesthesia 6. Status of dentition? Carious teeth should be removed at the time of the The surgeon should always stand by during surgery to avoid osteoradionecrosis. induction of anaesthesia as it may be diffi- 7. Mandible: Tumour may extend onto cult or impossible to intubate the patient, the FOM, involve periosteum, invade especially with bulky tumours that involve the inner cortex, or involve medullary the BOT and preclude elevation of the bone. Panorex shows gross involvement tongue to visualise the larynx. Should the of bone. Invasion of cortical bone is bet- anaesthetist be unable to intubate the lar- ter assessed with CT scan; MRI is supe- ynx, the surgeon may be able to intubate rior for assessing invasion of medullary through a laryngoscope, or do an emer- bone. In the absence of CT scans the gency tracheostomy or cricothyroidotomy. surgeon may elect to strip tumour off Nasal intubation facilitates resection of bone at the time of resection to inspect tongue tumours, and may be followed by the underlying bone for evidence of per- tracheostomy during the course of the op- iosteal and tumour infiltration and to eration. decide on how to proceed. If only the Perioperative antibiotics are prescribed for periosteum is involved then a marginal 24hrs. mandibulectomy (removal of cortical bone) will suffice. Should marginal

mandibulectomy be considered, then the vertical height of the mandible should be assessed clinically or by http://openbooks.uct.ac.za/ENTatlas 34-6 Johan Fagan

Surgical access

Good surgical access is essential in order to attain adequate resection margins, to con- trol bleeding, and for reconstruction.

Transoral access: Smaller tumours (T1-T2) are usually easily excised through the open mouth, especially in edentulous patients. The mouth is kept widely open either with a dental bite block (Figure 14) or with a self- Figure 16: Scoring vermillion border for accurate clo- retaining retractor, taking care to protect sure the teeth (Figure 15). First doing the mar- ginal mandibulectomy when tumour abuts Bleeding from the labial artery is controlled the mandible greatly facilitates the resec- with cautery. Incise the gingivolabial and tion. gingivobuccal mucosa >0.5cms from the bone to facilitate subsequent soft tissue clo- sure. Strip soft tissue off the mandible with monopolar cautery taking care (if possible) not to injure the mental nerve where it exits the mental foramen (Figure 17). Should the mandible need to be resected beyond the mental foramen, then the nerve is divided

and the tissues stripped from the lateral sur- Figure 14: Dental bite block is interposed between face of the bone (Figure 18). lateral teeth to keep mouth open

Mental nerve

Figure 17: Note preserved mental nerve

Figure 15: Self-retaining retractor in place

Midline lip-split: The lower lip is vertically divided in the midline after scoring/mark- ing the vermillion border so as to ensure an accurate repair of the lip (Figure 16). http://openbooks.uct.ac.za/ENTatlas 34-7 Open Access Atlas of Otolaryngology, Head & Neck Operative Surgery

Figure 18: Additional bony exposure

Mandibulotomy: Dividing the mandible following a midline lip-split affords excel- Figure 20: Osteotomy cuts lent access to the oral cavity with minimal When plating sets are not available, the attendant morbidity. The mandible is di- mandible is wired together at conclusion of vided with a Gigli saw (Figure 19) or a pow- surgery with stainless steel wiring by drill- ered saw. The osteotomy may be made ei- ing opposing holes on either side of the os- ther vertically or alternatively in a step- or teotomy (Figure 21). V-shaped fashion so as achieve a more sta- ble repair. The author places the osteotomy just anterior to the mental foramen in lat- eral tongue cancers (Figure 20). Gigli saws make wider cuts than powered saws; hence it is advisable to extract a tooth and make the osteotomy through the dental socket so as avoid devitalising both adjacent teeth. In dentate patients the mandible is preplated so as to ensure perfect dental alignment. Figure 21: Mandible wired together with stainless steel wire

Visor flap: This is achieved by cutting along the gingivolabial and gingivobuccal sulci about 0.5cm from the bone so as to permit placement of sutures when closing the wound, and then stripping the soft tissues from the outer aspect of the mandible. Take care not to transect the mental nerves if they can be saved. The skin flap is then retracted Figure 19: Gigli saw superiorly to expose the mandible (Figure 22).

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tongue (Figure 24b). Use diathermy to re- sect the tumour with at least 1cm margins. Palpate the tumour repeatedly during the course of the resection to ensure that the margins are adequate. Retain as much FOM mucosa as possible to preserve tongue mo- bility (Figure 23).

Figure 22: Visor flap and segmental mandibulectomy

Pull-through: This may be employed when the tumour stops some distance from the inner aspect of the mandible. Following bi- lateral neck dissections of Levels 1a and 1b, Figure 23: Abundance of uninvolved FOM mucosa the mandibular attachments of the anterior permits primary closure without tethering the tongue bellies of digastric, mylohyoid, geniohyoids and genioglossus are divided with electro- Maintain haemostasis throughout the re- cautery working from inferiorly. The mu- section; cauterise the ranine vessels and li- cosa of the FOM adjacent to the tongue tu- gate the lingual artery with silk when it is mour is then divided >0.5cm from the inner encountered. Obtain frozen section confir- aspect of the mandible (so as to facilitate mation of clear tumour margins if available. later repair), taking care not to injure the Orientate the specimen for the pathologist lingual and XIIns, or the submandibular with a suture before removing the specimen ducts. This permits the surgeon to deliver so as to not lose orientation. the FOM and tongue into the neck and to Partial glossectomy with mandibulectomy proceed with the resection. If a marginal or segmental mandibulec- Partial Glossectomy tomy is required then it should be done be- Having secured surgical access one can pro- fore proceeding to partial glossectomy as it ceed to resect the cancer. Complete Levels improves surgical exposure. Marginal man- 1a and b of the neck dissection(s) before dibulectomy is done with a powered oscil- proceeding to the resection; this permits the lating or reciprocating saw; or with small surgeon to cut through the muscles in the sharp osteotomes so as to avoid inadvert- FOM and tongue knowing the location of ently fracturing the mandible. With mar- the XIIn, lingual nerve and lingual artery. ginal mandibulectomy the cut is made obliquely so as to remove the inner cortex Partial glossectomy only (including the mylohyoid line) that abuts the tumour but to preserve the height of the A silk stay suture is placed anterior and/or outer cortex for mandibular strength. If a medial to the tumour to retract the normal segmental mandibulectomy is to be done, http://openbooks.uct.ac.za/ENTatlas 34-9 Open Access Atlas of Otolaryngology, Head & Neck Operative Surgery then preplate the mandible with a recon- • Too broad a flap in the FOM causes sal- structtion plate so as to ensure alignment of ivary pooling and adversely affects oral the teeth and a good bony contour. Bone transport cuts are made at least 2cm from visible tu- • A marginal mandibulectomy may be mour. Once the mandibulectomy has been done as part of the reconstructive pro- completed, keep the bone attached to the cedure to enable the surgeon to suture tumour specimen and divide the gingival the gingivobuccal or gingivolabial mu- mucosa on the inside of the bone cuts; this cosa to the FOM mucosa or flap releases tumour from bone and facilitates • Reduce the risk of an orocervical fistula delivery of the tumour into the surgical by approximating the mylohyoid to the field. Identify and preserve the submandib- digastric muscle in the neck, and ensur- ular duct(s), and the lingual and XIIns if ing that the tip of the suction drain is possible. The sublingual gland may be en- not placed in the upper neck countered in anterior FOM cancer resec- tions. No repair: Small and/or superficial resec- tions above the mylohyoid that do not com- Repair / Reconstruction municate with the neck dissection may be left open to heal like a tonsillectomy wound. Obtain meticulous haemostasis using ties, Resist the temptation to suture such defects monopolar and bipolar cautery before clos- as it may alter the shape of the tongue or ing the tongue defect. Carefully assess the tether the tongue. defect to determine how best to restore form and function i.e. mandibular integrity Primary closure (Figure 24a-c): Avoid teth- and contour, oral competence, mastication, ering or distorting the tongue and creating oral transport, swallowing and speech. a shortened, stumpy tongue. Preserving FOM mucosa is key to retaining tongue mo- Pointers bility (Figures 25a,b & 26a-c).

• Reconstructive surgeons should follow patients long-term to learn how best to optimise functional flap design • Tongue mobility is key to oral function • Tongue length is more important than width • Some defects are best left open to heal by secondary intention so as to retain mobility • Avoid tethering the tip of the tongue Figure 24a: T2 squamous cell carcinoma of lateral tongue • Never suture the edge of the tongue to the gingiva; in such cases maintain tongue mobility with a flap • Simply shaping a flap to match the re- sected tissue may well restore form but may have a poor functional result http://openbooks.uct.ac.za/ENTatlas 34-10 Johan Fagan

Figure 24b: Defect suitable for no repair or primary closure

Figure 25b: Excellent tongue mobility if adequate FOM mucosa preserved

Figure 24c: Primary closure with deep absorbable su- tures. Abundant FOM mucosa prevents tethering of the tongue

Figure 26a: Larger (T3) cancer of lateral tongue

Figure 25a: Defect following primary closure

Figure 26b: Hemiglossectomy

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Figure 26c: Even though primary closure permitted length and mobility to be retained, this patient may Figure 27: Buccinator flap have benefitted from additional bulk provided by a buccinator or radial free forearm flap Radial free forearm flap: This is a popular choice for the oral tongue as it is thin and Split skin graft: There is little point in graft- pliable and preserves mobility of the tongue ing a tongue defect other than when there is (Figure 28). An osseocutaneous flap can be concern about sealing a through-and- used as an onlay graft for marginal man- through communication to the neck, or a dibulectomy defects (Figure 29). (See chap- marginal mandibulectomy defect. The skin ter: Radial free forearm flap) is sutured to the margins of the defect with absorbable sutures, the ends of which are Anterolateral free thigh flap: (Figure 30) left a few centimetres long. A bolster of an- Muscle harvested with the flap can be tai- tiseptic-impregnated gauze is placed over lored to conform to the volume of the defect the skin graft and tied down with the long to be filled. However it is less pliable than sutures. The bolster is removed after about the radial free forearm flap and is only suit- 5 days. able for oral reconstruction in patients with thin thighs. Buccinator myomucosal flap: (Figures 27) This is an excellent flap for partial glossec- Free fibula flap: This is the workhorse of tomy and FOM defects as it has the same mandible reconstruction following seg- physical qualities as tissues of the FOM and mental mandibulectomy, but can also be oral tongue, has a reasonable amount of used as an onlay flap. It is suitable for dental bulk, and preserves mobility of the tongue. implants. (See chapter: Free Fibula flap) Because the pedicle crosses the mandible it is particularly well suited for edentulous pa- Pectoralis major flap: This is only used if tients, patients with missing teeth, or who other flaps listed are not available as it lacks have undergone marginal mandibulectomy. pliability and provides suboptimal func- (See chapter: Buccinator myomucosal flap) tional results. (See chapter: Pectoralis major flap)

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Final comments

Resecting tumours of the tongue is chal- lenging particularly in terms of maintaining oral function. One should not compromise resection margins for function. The surgical team has to master an array of reconstruc- tive techniques so as to secure the best func- tional outcomes. Figure 28: Radial free forearm flap Author & Editor

Johan Fagan MBChB, FCORL, MMed Professor and Chairman Division of Otolaryngology University of Cape Town Cape Town South Africa [email protected] Figure 29: Onlay osseocutaneous flap

Figure 30: Anterolateral free thigh flap used for lateral FOM and tongue defect

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